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Let X1,…,Xn$$ {\mathbf{X}}_1,\dots, {\mathbf{X}}_n $$ be a sequence of independence random vectors from Np(μ,Σ)$$ {N}_p\left(\boldsymbol{\mu}, \boldsymbol{\varSigma} \right) $$ with population correlation matrix Rn$$ {\mathbf{R}}_n $$, and its sample correlation matrix is denoted as R^n=(r^ij)p×p$$ {\hat{\mathbf{R}}}_n={\left({\hat{r}}_{ij}\right)}_{p\times p} $$, where the matrix element r^ij$$ {\hat{r}}_{ij} $$ represents the Pearson correlation coefficient between the i$$ i $$ and j$$ j $$ columns of the data matrix (X1,…,Xn)′$$ {\left({\mathbf{X}}_1,\dots, {\mathbf{X}}_n\right)}^{\prime } $$. R^n$$ {\hat{\mathbf{R}}}_n $$ is an interesting part in multivariate analysis, and the likelihood ratio test (LRT) statistic used to test the complete independence of all components of X$$ \mathbf{X} $$ can be expressed as a function of R^n$$ {\hat{\mathbf{R}}}_n $$. On this basis, under the condition that the sample size n$$ n $$ and the dimension p$$ p $$ satisfy p/n→y∈(0,1]$$ p/n\to y\in \left(0,1\right] $$ as n→∞$$ n\to \infty $$, we derive the moderate deviation principle (MDP) of the LRT statistic for the hypothesis testing problem H0:Rn=Ip$$ {H}_0:{\mathbf{R}}_n={\mathbf{I}}_p $$ vs H1:Rn≠Ip$$ {H}_1:{\mathbf{R}}_n\ne {\mathbf{I}}_p $$. [ABSTRACT FROM AUTHOR]

This paper focuses on the likelihood ratio test (LRT) statistics for different hypothesis tests. Assuming that a random sample is from a normal population, we make the sample size n and the dimension p close to infinity and satisfy p < n − c for some 1 ≤ c ≤ 4. Based on this assumption, the moderate deviation principle (MDP) for the LRT will be given under the null hypothesis. The corresponding numerical simulation results are shown at the end of the paper. [ABSTRACT FROM AUTHOR]

Disturbance‐resisting ability (DRA) of the restored network needs to be considered when making a restoration scheme of power systems, to ensure system security and reduce secondary blackout risk. This paper proposes an optimisation method of whole‐process restoration decision‐making with DRA of the restored network in consideration. Firstly, a load rate balance (LRB) index of the restored network is defined to represent the DRA index during restoration. Then, an optimisation model of whole‐process restoration decision‐making is established, considering the LRB index of the restored system. To solve the model by a linear programming method, the non‐linear terms in the model are transformed into linear forms. Finally, a time‐step decoupling method to reduce solving difficultness of the established model with the LRB index is derived, with purpose of accelerating the solving process. The numerical results of the IEEE 30‐bus system and a practical power system verify effectiveness of the proposed method to obtain a restoration scheme to balance the system restoration benefit and security. [ABSTRACT FROM AUTHOR]

Pumping is an indispensable operation in microfluidic applications. Numerous simple pumps have been developed to improve the portability of microfluidic systems, but they generally have poor controllability, short duration working time, and narrow pressure range, which compromises the functionality of portable microdevices. To address these limitations, we present a novel handheld, wide-range pressure pump that utilizes a disposable mini gas cylinder as a pressure source and a porous PDMS film as a flow-rate regulator. Specifically, by incorporating a set of parallel porous PDMS films with varying porosity, sectional area, and thickness into the pump system, and selectively switching between the branch flow circuits containing these porous PDMS films, we are able to finely regulate the flow rate of air released from the mini gas cylinder. This capability enables precise control of the pumping pressure applied to microfluidic devices over a wide range, thereby governing the fluid flow rate to accommodate different applications. The compact and lightweight nature of our pressure source renders this pump system particularly advantageous for field-portable microfluidic applications. Additionally, we demonstrate its capabilities through the performance of well-established microfluidic experiments, including concentration gradient generation and emulsion droplet production. We firmly believe that the compactness, operational simplicity, and disposability of our pump will greatly facilitate the widespread adoption of microfluidic technologies, particularly in point-of-care diagnostics and resource-limited settings. [Display omitted] • A compact, low-cost, electricity-free, and wide-range pressure pump is presented. • The pump can finely control flow rates without requiring expensive pressure sensors. • The pump allows performing long-term experiments with a wide range of flow rates. • The pump offers an on-site pumping solution for field-portable detection applications. [ABSTRACT FROM AUTHOR]

• A coordinated restoration model of TN/ADNs is constructed considering the fault repair scenario of ADNs. • A subsystem partition model of TN is established as part of the TN restoration model. • The frequency response characteristics of both synchronous and converter-based generators is considered in the TN/ADNs restoration model. • An ATC method is utilized to solve the coordinated restoration model of TN/ADNs considering the fault repair scenario of ADNs. With the development of active distribution network (ADN) technology, coordinated restoration of transmission network (TN) and ADNs has received widespread attention. As an important part of power system resilience, power system restoration should consider the influence of low-probability high-risk events. Such extreme events are often accompanied by component damage, so the coordination of restoration process and repair scheduling needs to be considered. First, the handling of fault repair scenario on TN and ADNs side during black-start restoration (BSR) is discussed. The interaction between the coordinated restoration of TN/ADNs and the fault repair schemes of ADNs is analyzed. Next, the coordinated restoration of TN/ADNs considering the ADN fault repair scenario is modelled in this paper. For the restoration model of TN, the restoration logic relationship of plants/lines, the subsystem division, frequency constraints of the restored system and the power scheduling constraints of source/load are considered. For the restoration model of ADNs, the restoration logic relationship of DGs/lines/buses, the scheduling logic of repair crews and emergency power sources, frequency constraints and the power scheduling constraints of source/load are considered. Then, an analytical target cascading algorithm is used to solve the optimization model. Finally, a TN/ADNs system is constructed by an IEEE_30 bus transmission system and two IEEE_33 bus distribution system, the numerical case study on the TN/ADNs system verifies that the distributed collaborative optimization of the TN/ADNs restoration plan and the fault repair plan of ADNs can improve the overall restoration efficiency during BSR. [ABSTRACT FROM AUTHOR]

• Evaluation of CO 2 -ECBM effects by thermodynamic characterization of coal adsorption of CH 4 and CO 2. • As the moisture content increases, the overall effect of CO 2 replacement of CH 4 becomes worse, but in some cases the opposite occurs. • The presence of H 2 O can enhance the adsorption of CO 2 in some cases. • Smaller pore size of coal will produce stronger wall superimposed effect. • Multiple H 2 O molecules form H 2 O clusters, which will attract CO 2 with high potential. In order to further clarify the thermodynamic properties of CH 4 and CO 2 adsorption in coal, a Monte Carlo method with a giant regular system was used to simulate the adsorption behavior of CH 4 and CO 2 in coal at different moisture contents and pore sizes. The results show that the adsorption of CH 4 and CO 2 in coal molecules is negatively correlated with the moisture content. As the pore size increases, the wall superimposed effect decreases, the stability of adsorption becomes less stable, and the selectivity of CO 2 adsorption decreases, but the space to accommodate gas molecules becomes larger, which makes the adsorption amount rise. The average heat of adsorption of CH 4 and CO 2 showed a decreasing and then increasing relationship with the moisture content, and a negative correlation with the pore size, and the effect of H 2 O on CO 2 is stronger than that of CH 4. With the increase of moisture content, the absolute value of adsorption energy increases overall, and the high potential of water clusters tends to attract CO 2 molecules more. With the increase of pore size, the wall superimposed effect weakens and the adsorption stability becomes worse, which makes the absolute value of adsorption energy smaller. The overall adsorption entropy of CH 4 and CO 2 has a negative correlation with moisture content and a positive correlation with pore size. The comparison of the slope of the fitted curves of adsorption entropy at different moisture contents adds that CO 2 mainly displaces CH 4 molecules in the middle of the pores at 3% moisture content. [ABSTRACT FROM AUTHOR]

Consider a multivariate linear regression model where the sample size is n and the dimensions of the predictors and the responses are p and m , respectively. We know that the limiting distribution of the likelihood ratio test (LRT) in multivariate linear regressions is different in the case of finite and high dimensions. In traditional multivariate analysis, when the dimension parameters (p , m) are fixed, the limiting distribution of the LRT is a χ 2 distribution. However, in the high-dimensional setting, the χ 2 approximation to the LRT may be invalid. In this paper, based on He et al. (2021), we give the moderate deviation principle (MDP) results for the LRT in a high dimensional setting, where the dimension parameters (p , m) are allowed to increase with the sample size n. The performance of the numerical simulation confirms our results. [ABSTRACT FROM AUTHOR]

Highlights: [•] The kinetics of Li-ion deintercalation in Li1.12[Ni0.5Co0.2Mn0.3]0.89O2 during first charging process are studied by GITT and EIS. [•] The D Li values calculated by EIS and GITT vary from 1.9×10−14 cm2 s−1 to 8.1×10−10 cm2 s−1 and 3.1×10−16 cm2 s−1 to 7.2×10−10 cm2 s−1. [•] GITT is a preferable technology for determining the D Li in Li1.12[Ni0.5Co0.2Mn0.3]0.89O2. [•] The electrode kinetics of Li1.12[Ni0.5Co0.2Mn0.3]0.89O2 is controlled by different process of electro-chemical reactions in the voltage range of 2.0–4.8V. [ABSTRACT FROM AUTHOR]

Abstract: Li[Ni0.5Co0.2Mn0.3]O2 was prepared using nickel–cobalt–manganese hydroxide as the precursors, then resultant Li[Ni0.5Co0.2Mn0.3]O2 was surface modified by FePO4 through co-precipitation routine. The samples of bare and FePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 were characterized with various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that the thickness of FePO4-coating layer is about 5nm, and FePO4-coating layer not affects the crystal structure of the pristine Li[Ni0.5Co0.2Mn0.3]O2. Thus FePO4-coating layer is only a thin layer with amorphous structure. Furthermore, the FePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 exhibits much better cycle performance, higher capacity retention ratios of 91.2% at 1C after 50 cycles since the FePO4-coating effectively prevents the reaction between active material and electrolyte on the process of charge/discharge under a high charge cutoff voltage of 4.6V. Meanwhile, the rate capability of FePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 is enhanced, and it obtained at 0.2, 0.5, 1, 2, 5 and 10C rates are 213.1, 207.9, 203.8, 190.2, 171.2 and 151.6mAhg−1, respectively. [Copyright &y& Elsevier]

• We formulate a resilient backbone grid model in detail. • We propose a method to map constraints of nodes and lines so as to guarantee the global PMU-observability of not only the whole network but also the backbone grid according to the principle of the optimal PMUs placement (OPP). • We deal with the solutions that do not satisfy the AC power flow by adding linear-cut constraints. • The analysis shows the collaborative planning method can not only ensure the global observability of both the whole network and the backbone grid but also reduce the differentiated investment and PMU-placement cost. Constructing a resilient backbone grid can enhance the power supply capability and disaster resistance ability of power systems in some disaster scenarios. At the same time, it is of great importance to guarantee the global observability of power systems for real-time control and operation management during disasters. On the basis of these two requirements, a mixed integer linear programming (MILP) model is proposed to co-optimize backbone grid planning and PMU placement. Firstly, a backbone grid model is formulated with considering the node-importance and line-importance rate index. The disaster-resisting ability of power systems can be promoted by hardening important nodes and lines selectively. Meanwhile, according to the principle of the optimal PMUs placement (OPP), a method to map constraints of nodes and lines is proposed in order to guarantee the global PMU-observability of not only the whole network but also the backbone grid. Then, the solutions that do not satisfy the AC power flow will be removed by adding linear-cut constraints. Finally, the simulation was demonstrated on New England 10-unit 39-bus and IEEE 118-bus systems to prove the validity of the proposed method. The results show that the collaborative planning method can not only ensure the global observability of both the whole network and the backbone grid but also reduce the differentiated investment and PMU-placement cost. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) are recognized as one of the most promising alternatives for large-scale application due largely to low-cost and sustainable supply-chain. The crucial task is to explore the next generation of cathode materials with satisfactory performances at low cost. In this work, Na 2 FePO 4 F/C nanocomposite (NFPF/C-PG) has been synthesized via liquid route using polyfurfuryl alcohol (PFA) as grain size controller followed by solid-state reaction using glucose as carbon sources. PFA formed in situ polymerization not only prohibits effectively the aggregation of nanoparticle, but also plays a vital role in the construction of carbon network. As a proof-of-concept application, the NFPF/C-PG shows outstanding electrochemical properties as cathode material for sodium ion batteries, which delivers discharge capacities of 73.8 mAh/g with retaining 86.1% of initial capacity over 200 cycles at 1C. Unlabelled Image • Na 2 FePO 4 F/C composite is synthesized with the synergism of polyfurfuryl alcohol. • The Na 2 FePO 4 F nanoparticles are uniformly distributed in graphitized carbon. • NFPF/C-PG shows excellent cycling performance and rate capability. [ABSTRACT FROM AUTHOR]

CO 2 -ECBM is an effective energy saving and emission reduction technology. Among them, the permeability of coal seam will affect the CO 2 injection efficiency, which is the key factor affecting the CH 4 production. In order to reveal the evolution of reservoir permeability, effective stress, adsorption/desorption effect, and binary gas seepage and diffusion are considered. The research results indicate that the evolution of permeability can be summarized into two stages. The permeability during the CO 2 undisturbed period is mainly controlled by the effective stress, which exhibits a parabolic relationship with permeability. The CO 2 disturbed period is mainly controlled by the strain, which exhibits a negative correlation with permeability. Increasing the injection pressure, during the CO 2 undisturbed period, the effective stress increases, the strain decreases, and the higher the permeability. During the CO 2 disturbed period, the lower the effective stress, the higher the strain, and the lower the permeability. Increasing the injection temperature, the greater the effective stress and permeability in the undisturbed period. In the CO 2 disturbed period, the competitive adsorption intensifies, the larger the strain, and the faster the permeability decreases. Increasing the initial water saturation, the slower the gas transportation rate. The slower the effective stress rises in the CO 2 undisturbed period, the lower the permeability. In the CO 2 disturbed period, the smaller the strain, and the higher the permeability. In summary, injection pressure, temperature, initial water saturation will have an impact on the permeability, in engineering practice, it is not the case that the higher the injection pressure, the higher the injection temperature, the smaller the initial water saturation is the better. • The permeability of coal seam is affected by effective stress and strain. • The evolution of the reservoir permeability during the CO 2 -Enhanced coalbed methane recovery has been divided into 2 stages. • The influence mechanism of injection pressure, injection temperature and initial water saturation of coal seam on reservoir permeability during the CO 2 -Enhanced coalbed methane recovery process is analyzed. [ABSTRACT FROM AUTHOR]

As an efficient and clean energy, coalbed methane development and utilization have deep significance in promoting energy conservation and emission reduction, reducing greenhouse gas emissions. Therefore, molecular simulation was utilized to study the influence of N2/CO2 on the adsorption and diffusion of methane in coal under different gas injection methods and to elucidate the influence of varying gas injection methods on the efficiency of coalbed methane extraction, which provides a basis for the efficient development of coalbed methane. The results show that the adsorption effect of gases in coal decreases with the increase of temperature and increases with the rise of pressure, and the adsorption performance of the three gases in coal shows the law of CO2 > CH4 > N2. In addition, the injection of CO2/N2 had an obvious inhibition effect on CH4 adsorption, and the inhibition effect of CO2 was more significant, and the inhibition effect on CH4 adsorption reached the maximum when the two gases were mixture injected. In terms of diffusion, compared with separate injection, mixed injection of N2 + CO2 promotes CH4 diffusion more effectively, which can be reflected in the relative concentration distribution and velocity distribution. The injection of N2 helps to increase the porosity of coal, and the injection of CO2 and N2 + CO2 will lead to the decrease of porosity, but the mixed gas injection has less effect than the injection of CO2 alone. [ABSTRACT FROM AUTHOR]

Let u(k)(t, x) be the solution to the parabolic Anderson model driven by a space-time white noise on the interval [0, k] with Neumann, Dirichlet, or periodic boundary conditions. In this paper, we investigate the almost sure central limit theorems for spatial averages of the form ∫ 0 k u k t , x dx as k tends to infinity. [ABSTRACT FROM AUTHOR]

In this paper, THM model and coal molecular model are established to study the gas adsorption and desorption behavior in coal seam at different injection pressures. The results show that, the total energy decreases during the adsorption process and increases in the desorption process. CO 2 has a stronger adsorption capacity which is in a dominant position in the competition adsorption process, while N 2 is in a weak position. The order of the diffusion coefficient is N 2 >CH 4 (CH 4 –N 2) > CH 4 (CH 4 –CO 2) > CO 2. The diffusion coefficient does not necessarily increase with the increase of injection pressure. At the same injection pressure, the relative concentration of CH 4 in the CH 4 –CO 2 system is greater than that in the CH 4 –N 2 system, and injection of CO 2 to promote CH 4 desorption is significantly better than the injection of N 2. With the increase of injection pressure, the average relative concentration of CH 4 /CO 2 /N 2 in the vacuum layer increased. The optimal injection pressure for N 2 injection to promote CH 4 desorption is 2 MPa, and the reasonable injection pressure for CO 2 injection is 1–3 MPa. • THM model and coal molecular model are established to study the gas adsorption and desorption at different injection pressures. • The total energy of the system decreases during the adsorption process and increases in the desorption process. • The diffusion coefficient does not necessarily increase with the increase of gas injection pressure. • Relative concentration of CO 2 in the vacuum layer is lower than N 2 , the adsorption performance of CO 2 is greater than N 2. [ABSTRACT FROM AUTHOR]

• The thermo-hydro-mechanical flow (THM) model of water-bearing coal seam is established. • Coal seam water can hinder gas migration, thus reducing CH 4 production and CO 2 /N 2 storage. • Different migration rates of CO 2 and N 2 lead to different breakthrough times of CO 2 /N 2 -ECBM. • The injection ratio of mixed gases (CO 2 , N 2)will impact parameter of coal seam, including reservoir permeability, CH 4 production, and CO 2 /N 2 storage capacity. • CO 2 displacement mainly utilizes competitive adsorption characteristics, while N 2 displacement utilizes "high-speed scouring" effect and " dredging, expanding " effect on fractures. Gas injection to increase coalbed methane production is an effective energy saving and emission reduction technology, with triple benefits of clean energy production, environmental protection and safety production. In this paper, a coupled thermo-hydro-mechanical flow (THM) model is developed, the effects of different injected gases on ECBM are considered, the effect of initial water saturation on CO 2 /N 2 -ECBM is quantified using the control variable method. Exploring changes in storage and production during the injection gas mixture enhanced CBM recovery (GM-ECBM). The results show that: The breakthrough time of CO 2 injection was much later than N 2 injection. The higher the initial water saturation, the lower the CH 4 production and gas storage. CO 2 injection will reduce the permeability of coal seam and damage it, while N 2 injection can effectively restore the permeability. The higher the initial water saturation, the slower the permeability decrease during CO 2 -ECBM and the slower the permeability increase during N 2 -ECBM. Increasing the N 2 injection concentration before the N 2 breakthrough time can promote CH 4 production, and increasing the CO 2 injection concentration near the N 2 breakthrough time will delay the N 2 breakthrough time and provide more time for CH 4 to migration in the pore space, which will increase the CH 4 production. When injecting gas mixture into water-bearing coal seam, the higher the initial water saturation, the slower the coal seam permeability increases when N 2 is disturbed, and the slower the coal seam permeability decreases when CO 2 and N 2 are co-disturbed, while both production and storage will decrease. [ABSTRACT FROM AUTHOR]

• A fluid–solid thermal coupled model of CO 2 -ECBM is established. • Binary gases (CO 2 and CH 4) infiltration and diffusion and non-isothermal adsorption are considered in the model. • Temperature is a key factor affecting CH 4 production and CO 2 storage, increasing injection temperature can significantly accelerate the process of gas displacement and CO 2 storage. • The CO 2 storage and the CH 4 production decrease with the increase of initial reservoir temperature. • Low Young's modulus and high Poisson's ratio can effectively increase CO 2 storage and CH 4 production. CO 2 -ECBM can not only improve the production of CBM, but also contribute to CO 2 geological sequestration, which has multiple economic effects. In this paper, COMSOL simulation software was used to conduct numerical simulation studies on the 3# coal seams in Qinshui Basin. A fully coupled model of coal deformation, gas flow and migration, and thermal transfer was established to evaluate the effect of temperature on the production of CBM by CO 2 injection. The results indicates that temperature is a key factor affecting CH 4 production and CO 2 storage. Increasing injection temperature can significantly accelerate the process of gas displacement and the CO 2 storage is more sensitive to temperature than the CH 4 production. In contrast, both the CH 4 production and the CO 2 storage decrease with the increase of initial temperature of coal seam and the permeability will decrease faster. With the increase of injection time, the effective influence radius of displacement increases, but the increment of influence radius decreases gradually. The lower the initial temperature of the coal seam, the larger the influence radius, the influence radius increases as a whole with the increase of time. Low Young's modulus or high Poisson's ratio can effectively increase CO 2 storage and CH 4 production. [ABSTRACT FROM AUTHOR]

Key Message: By integrating QTL mapping, transcriptomics and metabolomics, 138 hub genes were identified in rapeseed root response to aluminum stress and mainly involved in metabolism of lipids, carbohydrates and secondary metabolites. Aluminum (Al) toxicity has become one of the important abiotic stress factors in areas with acid soil, which hinders the absorption of water and nutrients by roots, and consequently retards the growth of crops. A deeper understanding of the stress-response mechanism of Brassica napus may allow us to identify the tolerance gene(s) and use this information in breeding-resistant crop varieties. In this study, a population of 138 recombinant inbred lines (RILs) was subjected to aluminum stress, and QTL (quantitative trait locus) mapping was used to preliminarily locate quantitative trait loci related to aluminum stress. Root tissues from seedlings of an aluminum-resistant (R) line and an aluminum-sensitive (S) line from the RIL population were harvested for transcriptome sequencing and metabolome determination. By combining the data on quantitative trait genes (QTGs), differentially expressed genes (DEGs), and differentially accumulated metabolites (DAMs), key candidate genes related to aluminum tolerance in rapeseed were determined. The results showed that there were 3186 QTGs in the RIL population, 14,232 DEGs and 457 DAMs in the comparison between R and S lines. Lastly, 138 hub genes were selected to have a strong positive or negative correlation with 30 important metabolites (|R|≥ 0.95). These genes were mainly involved in the metabolism of lipids, carbohydrates and secondary metabolites in response to Al toxicity stress. In summary, this study provides an effective method for screening key genes by combining QTLs, transcriptome sequencing and metabolomic analysis, but also lists key genes for exploring the molecular mechanism of Al tolerance in rapeseed seedling roots. [ABSTRACT FROM AUTHOR]

The morphology-controlled Li 2 FeSiO 4 /C cathode material is successfully synthesized by a sol-gel method, in which commercial, spherical and cubic Fe 2 O 3 are respectively used as iron sources. By controlling the Fe 2 O 3 precursors' morphologies, the morphology and grain size of the Li 2 FeSiO 4 /C materials can be purposefully controlled via morphology-inheritance strategy. The morphologies, sizes, elemental distributions and structures of the as-prepared Li 2 FeSiO 4 /C materials are confirmed by field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results show that the as-synthesized Li 2 FeSiO 4 /C samples exhibit well-defined morphologies due to the homogeneous and well-crystallized Fe 2 O 3 precursors. Comparing with Li 2 FeSiO 4 /C synthesized by commercial Fe 2 O 3 precursor, the Li 2 FeSiO 4 /C materials prepared by spherical or cubic Fe 2 O 3 precursors exhibit eminent electrochemical properties, e.g., high initial reversible capacities of 214.1 mAh g −1 for LFS/C-S and 206.5 mAh g −1 for LFS/C-C at 0.1 C and good cyclic stability (93.1% for LFS/C-S and 91.5% for LFS/C-C). In particular, the spherical LFS/C-S material with better fluidity and less agglomeration displays excellent rate capability of 105.4 mAh g −1 at 10 C. Therefore, the control of the morphology and size during preparation process of Li 2 FeSiO 4 /C cathode materials will open a new route for the development of high performances lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Fire is an important regulator of ecosystem dynamics in boreal forests, and in particular has a complicated association with growth and physiological processes of fire-tolerant tree species. Stable isotope ratios in tree rings are used extensively in eco-physiological studies for evaluating the impact of past environmental (e.g. drought and air pollution) factors on tree growth and physiological processes. Yet, such studies based on carbon (δ13C) and oxygen (δ18O) isotope ratios in tree rings are rarely conducted on fire effect, and are especially not well explored for fire-tolerant trees. In this study, we investigated variations in basal area increment and isotopes of Larix gmelinii (Rupr.) Rupr. before and after three moderate fires (different fire years) at three sites across the Great Xing'an Mountains, Northeastern China. We found that the radial growth of L. gmelinii trees has significantly declined after the fires across study sites. Following the fires, a simultaneous increase in δ13C and δ18O has strengthened the link between the two isotopes. Further, fires have significantly enhanced the 13C-derived intrinsic water-use efficiency (iWUE) and largely altered the relationships between δ13C, δ18O, iWUE and climate (temperature and precipitation). A dual-isotope conceptual model revealed that an initial co-increase in δ13C and δ18O in the fire year can be mainly attributed to a reduction in stomatal conductance with a constant photosynthetic rate. However, this physiological response would shift to different patterns over post-fire time between sites, which might be partly related to spring temperature. This study is beneficial to better understand, from a physiological perspective, how fire-tolerant tree species adapt to a fire-prone environment. It should also be remembered that the limitation of model assumptions and constraints may challenge model applicability and further inferred physiological response. [ABSTRACT FROM AUTHOR]

[Display omitted] • The nanosphere structure can be well maintained with the introduction of the S-Mo-S bond through in-situ ion exchange strategy. • The high conductivity of MoO 2 significantly increases the electronic/ionic transport. • The MoO 2 /MoS 2 heterostructure displays enhanced electrochemical kinetic behaviors for SIBs. Mo-based heterostructures offer a new strategy to improve the electronics/ion transport and diffusion kinetics of the anode materials for sodium-ion batteries (SIBs). MoO 2 /MoS 2 hollow nanospheres have been successfully designed via in-situ ion exchange technology with the spherical coordination compound Mo-glycerates (MoG). The structural evolution processes of pure MoO 2 , MoO 2 /MoS 2 , and pure MoS 2 materials have been investigated, illustrating that the structure of the nanosphere can be maintained by introducing the S-Mo-S bond. Based on the high conductivity of MoO 2 , the layered structure of MoS 2 and the synergistic effect between components, as-obtained MoO 2 /MoS 2 hollow nanospheres display enhanced electrochemical kinetic behaviors for SIBs. The MoO 2 /MoS 2 hollow nanospheres achieve a rate performance with 72% capacity retention at a current of 3200 mA g−1 compared to 100 mA g−1. The capacity can be restored to the initial capacity after a current returns to 100 mA g−1, while the capacity fading of pure MoS 2 is up to 24%. Moreover, the MoO 2 /MoS 2 hollow nanospheres also exhibit cycling stability, maintaining a stable capacity of 455.4 mAh g−1 after 100 cycles at a current of 100 mA g−1. In this work, the design strategy for the hollow composite structure provides insight into the preparation of energy storage materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical porous catalysts rich in Cu-N x sites are designed by combining the structural regulation and defect engineering. • Cu-ONCs manifest excellent ORR activity in both alkaline and neutral media. • Cu-ONCs based neutral ZABs demonstrate exceptional stability and high power density. Novel carbon nanomaterials containing N-coordinated metal centers present an advantage in promoting the oxygen reduction reaction (ORR). Despite considerable progress, substantial challenges persist with the advancement of neutral Zinc-air batteries (ZABs), particularly in optimizing the trade-off between the catalytic activity and stability. Herein, employing nanoporous carbon impregnated with Cu(II)-phenanthroline complexes to prepare Cu-ONCs catalysts rich in Cu-N x sites. Controllable carbon defects to capture Cu2+ enable the enrichment of metal sites on the porous carbon surface, and simultaneously effectively suppress the aggregation of active centers. The metal moieties, specifically Cu-N x , are incorporated into the porous N-doped carbon, thereby introducing accessible active sites within the partially graphitized carbon framework. Furthermore, the abundant mesopores inside the carbon nanofibers promote the exposure of accessible active sites to substantially augment the electrochemically active electrochemically active area area. Given the unique structure and composition, Cu-ONCs show outstanding ORR activity in neutral and alkaline media, alone with negligible decay observed after 3000 cycles. Moreover, Cu-ONCs based neutral ZABs demonstrate a peak power density of 48.28 mW cm−2 and impressive rate performance. This work provides defects/vacancies insight on transition metal (TM)-based carbon support to facilitate the advancement of cutting-edge neutral ZABs. [ABSTRACT FROM AUTHOR]

Calcium carbide-derived carbons (CCDCs) produced by chlorination of CaC at various temperatures (400-800 °C) possess highly controllable microstructure and porosity, allowing them to serve as excellent electrode materials for the application of supercapacitor. This paper focused on the effect of pore size and specific surface area (SSA) of CCDC on its electrochemical behavior. Microstructure and micropore characteristics of CCDC were characterized by N adsorption/desorption isotherms, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that SSA and average pore size increased with the increase of synthesis temperature from 400 °C to 600 °C, and then decreased when temperature reached to 800 °C. Meanwhile, a correlation between specific capacitance and SSA of micropores (less than 2 nm in diameter) has been studied. It has been found that the supercapacitor using the CCDC prepared at 600 °C as electrode material in 6 M KOH showed the maximum specific capacitance and energy density (53.61 F g and 7.08 W h kg), outstanding rate capability, lower IR drop and 96 % retention of initial capacity over 5,000 cycles. [ABSTRACT FROM AUTHOR]

Lithium-rich manganese-based cathode materials (LRMCs) can be regarded as one of the most potential cathode materials for the next-generation high-energy Li-ion batteries due to the extra oxygen redox, which can greatly increase the actual output energy density of LRMCs. Nevertheless, the structure degradation and inevitable loss of oxygen will be triggered by the irreversible oxygen redox, which will cause a significant decline in cyclic performance and limited initial Coulombic efficiency, thus restricting their industrial applicability. Herein, the LRMCs with the submicron-sized single-crystal morphology and sodium doping are prepared by molten salt treatment with NaCl. On one hand, the submicron-sized single-crystal cathode effectively reduces the diffusion path for Li+ due to the smaller particle dimensions. On the other hand, Na+ doping expands the Li slab spacing, promoting the transport of Li+. The results show that the as-prepared material can purposefully alleviate oxygen release, improve structure stability, and increase the Li+ diffusion rate for the pristine LRMCs. Moreover, the as-prepared material in this study exhibits a higher reversible capacity of 282.8 mAh g−1 at 0.1 C and displays good cyclic performance, retaining a capacity rate of 80.9% after 200 cycles at 1 C. Therefore, this study offers a potential exploration for designing LRMCs with high energy density and excellent cyclic performance, which are achieved through building submicron-sized single-crystal morphology and introducing cationic doping. [Display omitted] • The Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (LMNCO) is modified by the molten salt treatment with NaCl. • The obtained LMNCO characterizes submicron sized single crystal morphology and Na+ doping. • The submicron sized single crystal morphology and Na+ doping prompt the Li+ diffusion of LMNCO. • The enhanced specific capacity and initial Coulombic efficiency are obtained by the modified materials. [ABSTRACT FROM AUTHOR]

Tin-based materials possess a high-capacity as a potential anode for Na-ion batteries (SIBs), but the inferior electric conductivity and sluggish reaction kinetics limit their further development. In this paper, we have successfully constructed multiphase structure SnO 2 /SnS/SnS 2 by combining the electrochemical induction and in-situ hydrothermal method to effectively alleviate these problems. The continuous addition of sulfur source (thioacetamide, TAA) results in the formation of a transition from pure product (SnO 2) to double structure (SnO 2 /SnS), and finally multiphase structure (SnO 2 /SnS/SnS 2). Compared to single or bimetal chalcogenides, the tri-metal chalcogenides have strengthened synergistic effects between diverse components. Additionally, the SnO 2 /SnS/SnS 2 composites exhibit small grain size and abundant mesoporous structure, which aid to shorten the distance of ions transfer and increase surface active sites for Na-ions storage. The SnO 2 /SnS/SnS 2 anode displays optimal diffusion coefficient (1.94 × 10−15 cm2 s−1) and cycling durability, with a recoverable specific discharge ability of 401 mA h g−1 over 100 cycles at 100 mA g−1 and a maintenance overpasses 77 %. These results indicate that the construction of multiphase structures is a prospective way to improve the reaction kinetics of Sn-based materials for SIBs. • Tin-based multiphase structures were prepared through combining the electrochemical synthesis and in-situ hydrothermal. • The composite has abundant mesoporous structures and nanoscale amorphous particles, which aid in electrolyte infiltration. • Benefiting from the synergistic effects among three substances, the composites exhibit excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

P2-type Fe/Mn-based oxides are considered as the competitive cathode materials for sodium-ion batteries because of high specific capacity and low material cost. However, it suffers from poor cycling stability and unsatisfactory rate capability. Herein, the lithium-doped Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2 microspheres are successfully synthesized via a three-step method. Benefiting from the synergetic effect of the double modification through the morphology controlling and lithium doping, the Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2 delivers an improved cycling stability and rate performance. Moreover, fluorine is successfully introduced to further improve the electrochemical performance of the Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2. Fluorine doping can boost the stability of the material crystal structure because of the strong electronegativity of fluorine and the stable fluorine-metal bond. Meanwhile, fluorine doping avoids the formation of extra O3 phase by reducing the average valence of transition metals. Most importantly, P2-type 10 mol% F-Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2 shows a high discharge specific capacity of 182.0 mAh g-1 at 20 mA g-1, excellent capacity retention of 90.0% after 50 cycles and outstanding rate performance of 128.7 mAh g−1 at 400 mA g-1. Apparently, such a modification strategy apparently promotes the electrochemical performances of the P2-type Fe/Mn-based oxide and increases the commercial application possibilities of this cathode material in sodium-ion batteries. • P2/O3-type Li-doped NLFMO microspheres are successfully synthesized. • NLFMO microspheres delivers improved cycling stability and rate performance. • Pure P2-type NLFMO microspheres are synthesized by 10 mol% fluorine doping. • P2-type 10 mol% F-NLFMO displays higher specific capacity than NLFMO. • P2-type 10 mol% F-NLFMO also shows better cyclic stability and rate capability. [ABSTRACT FROM AUTHOR]

The structural collapse of manganese-based materials during cycling greatly restricts its development in Sodium-ion batteries (SIBs). Hence, two-phase structures with different manganese valence states are designed based on an alternating voltage approach to mitigate volume expansion via two-phase coordination. Here distinct manganese valence states of precursor are driven via atmosphere. And in the following heat-induced phase transition, the elemental valence state is the decisive key for the structural and compositional evolution. In a batch of synthetic materials, MnO/MnS with bivalent states of manganese performs best as expected. Furthermore, NaPF 6 in DEGDME is taken to replace the traditional carbonate electrolyte which is prone to produce unstable SEI film and leading to polarization. A series of characterization methods confirm that the energy barrier of charge transfer at the interface between electrolyte and electrode is the main factor determining the electrochemical characteristics of the interface and thus the energy storage performance. Ultimately, carbon dots (CDS) with rich functional groups are introduced in an effort to further promote the conductivity of MnO/MnS, and the in-situ generated C-S-Mn bond enhances electrochemical kinetic behaviors. This work provides an approach for designing manganese-based materials and the selection of electrolytes in sodium energy storage. [Display omitted] • MnO/MnS and MnO/MnS@CDS are prepared based on an alternating voltage approach. • The heterostructure shows good sodium storage performance in ether electrolyte. • The SEI film formed in ether electrolyte ensures efficient sodiation dynamics. • In-situ generated C-S-Mn bond elevates pseudocapacitive behavior. [ABSTRACT FROM AUTHOR]

The exploitation of efficient electrocatalysts is vital for zinc-air batteries (ZABs). Fe-based catalysts exhibit insufficient bifunctional activity and stability, impeding the further development of ZABs. Herein, an efficient bifunctional electrocatalyst (PFeNC@NiFe-LDH) is rationally constructed and designed through the pore-creating and in-situ-generated interface nanoengineering approach. In this process, in-situ Fe-modified framework material (Fe-ZIF-8) regulates intermetallic distance to prevent Fe atom agglomeration. Fe-ZIF-8 and activator are co-heated to enable a highly porous structure and single-atom catalyst (PFeNC). The porous defect sites in PFeNC can be served as nucleation centers to anchor NiFe-LDH nanosheet, reinforcing the stability of the complex and enhancing bifunctional catalytic activity. Benefiting from single-atoms dispersing, interface effect, hierarchical pore channel, and synergistic effect, the PFeNC@NiFe-LDH demonstrates eminent bifunctional oxygen electrocatalytic performance (ΔE = 0.66 V), high stability, and rapid kinetic process (73.1 mV dec-1) for oxygen reduction reaction(ORR)), far outperforming the commercial Pt/C + IrO 2 benchmark (ΔE = 0.87 V). Furthermore, the PFeNC@NiFe-LDH as a ZABs air-electrode delivers prominent stability last 16 days. These results take a perspective to devise bifunctional composite catalysts with NiFe-LDH grown on carbon-based materials. • The strong interface structure of the composite material (PFeNC@NiFe-LDH) is prepared through in-situ interface nanoengineering. • The controlled distance of iron atoms is beneficial to catalyze the improvement of active sites. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) multicolor NiMn LDH nanoparticles are produced without the need of a substrate by using a one-step N source-assisted hydrothermal reaction and various Mn ratios, resulting in a variety of hues. Their physical features and architectures disclose their intriguing electrochemical capabilities, resulting in improved rate performance throughout the electrochemical process. [Display omitted] • A facile strategy was proposed to synthesis fascinating 3D multicolor NiMn LDH. • NiMn LDH polychromatic phenomenon in which the content of Mn element plays a key role. • NiMn LDH was grown on porous carbon to enhance the electrochemical performance of LDH. • The as-synthesized NiMn LDH /F-AC demonstrate excellent capacity at high current. Layered Double Hydroxide (LDH), as a typical two-dimensional electrochemical storage material, has shown great potential in the field of supercapacitors. Herein, three-dimensional (3D) multicolour NiMn LDH nanoparticles were prepared without substrate using a one-step formula using different levels of Mn and various N sources to assist the hydrothermal reaction. The appearance of the designed materials expressing different colors is owing to the Mn content of the reference playing an important role, where the electrochemical performance and structural stability also become more prominent. Adding a suitable Mn content to the G-NiMn LDH maintains the structural integrity and ultra-flake-like structure, revealing a uniform size of 2 μm compared with B-NiMn LDH. It provides abundant redox sites, enabling the green LDH to exhibit excellent electrochemical performance in appearance (1108 F g−1@1 A g−1 in G-NiMn LDH). Furthermore, the in-situ growth of G-NiMn LDH nanomaterials (denoted as G-NiMn LDH/F-AC) on F-doped activated carbon material (F-AC) brought increased active sites, effectively inhibited the accumulation of nanosheets, revealing a good rate capability (78 %@15 A g−1). Moreover, the asymmetric supercapacitor's positive and negative electrodes are G-NiMn LDH/F-AC and biomass carbon, up to 73 F g−1. This study methodology offers a novel viewpoint on the manufacture and discussion of LDH for understanding electrode materials' structural and surface chemical characteristics. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) are utilized in supercapacitors as electrode materials for their high theoretical capacity. The fabrication of TMSs/carbon composite for supercapacitors has gained much interest because of its favorable electron conductivity, and mechanical strength. Herein, the biomass absorption method is applied to fabricate NiS/Ni 3 S 4 carbon composite. Carbon-wrapped nickel (Ni@C) is obtained through the carbonization of Ni2+ absorbed biomass. The wrapping structure can prevent nanoparticles from stacking and structure collapse. In the following process, utilizing Na 2 SO 4 as activator and sulfur source, it etches the carbon surface to create multistage pore structure, and meanwhile, the carbon matrix reduced part of SO 4 2- to form S2-/S that can be captured by the available active sites, leading to produce S-S/C-S bond. Subsequently, A-NiS/Ni 3 S 4 @C and NiS/Ni 3 S 4 @C were effectively obtained after sulfuring A-Ni@C and Ni@C in the condition of hydrothermal, respectively. Benefitting from the bonding structure and coating characteristics, A-NiS/Ni 3 S 4 @C presented better ion diffusion behavior and exhibited a specific capacity of 560.6 F g−1 at 1 A g−1, F g−1 higher than that of NiS/Ni 3 S 4 @C. Furthermore, the A-NiS/Ni 3 S 4 @C was also assembled into a hybrid supercapacitor and showed a specific capacity of 118.6 F g−1 at 1 A g−1. • Biomass-derived carbon well confined NiS/Ni 3 S 4 nanoparticles was successfully prepared. • Nanoparticles can be obtained efficiently via biomass absorption method. • Na 2 SO 4 can enhance the property in a mild way by etching the carbon surface physically and form C-S/S-S. • Offering a new method for the fabrication of nanocomposite and mild way for polish the properties of carbon. [ABSTRACT FROM AUTHOR]

Nickel-rich layered cathodes have received extensive attention because of their relatively high energy density. However, the poor rate performance and inadequate cycling stability severely hinder its large-scale applications. Herein, a multi-functional modification strategy combining dual-site Mg/Nb co-doping with in-situ derived LiNbO 3 coating layer is proposed. Mg2+ doped as pillar ions at Li sites can reduce the disorder of Li+/Ni2+, while Nb5+ doped at transition metal sites can improve structural stability due to its stronger Nb-O binding energy. Moreover, LiNbO 3 ionically conductive nano-scale coating layer can effectively improve interface properties of the material. Benefitting from the synergistic effect of multi-functional modification strategy, the LiNi 0.83 Co 0.12 Mn 0.05 O 2 cathode material co-modified with 2 mol% Mg and 1.4 mol% Nb exhibits extraordinarily enhanced electrochemical performance, which can display an excellent capacity retention of 84.1% after 200 cycles at 1 C and a high specific capacity of 132.9 mAh g−1 at the ultra-high rate of 30 C. Furthermore, the multi-functional modification strategy can also effectively alleviate grain-level intergranular cracks and structural degradation during long-term cycling. These results demonstrate that simultaneously using two types of doping cations together with in situ derived coating layer is an efficient and feasible modification strategy for Ni-rich layered cathodes. [ABSTRACT FROM AUTHOR]

The Mn doped spherical Li 2 FeSiO 4 /C cathode materials are successfully synthesized through a citric acid-assisted sol-gel method. The effects of Mn doping on the chemical composition, structure characteristics, morphology and elemental distribution of the as-prepared polyanionic cathode materials are investigated by the inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM) and energy-dispersive X-ray spectroscope (EDX). The results indicate that the alien atom Mn can effectively and equably dope into the samples as well as maintain the original spherical morphology. Besides, the electrochemical measurements reveal that the sample doped with 5% Mn delivers the highest initial discharge capacity of 248.5 mAh g −1 at 0.1C under ambient temperature in a voltage range of 1.5–4.8 V, the retention of the capacity is as high as 91.9% after 200 cycles. Additionally, the sample doped with 5% Mn also exhibits a good rate capability with a discharge capacity of 105.6 mAh g −1 even at a high rate of 10C. The excellent electrochemical performances can be ascribed to the appropriate Mn doping, which can effectively optimize the crystal structure of Li 2 FeSiO 4 /C and facilitate the diffusion coefficient of lithium-ion during cycling process. [ABSTRACT FROM AUTHOR]

Although FeF 3 and its hydrates have been studied as the cathode materials for Li ion batteries (LIBs), herein the FeF 3 /graphene composite with sheet-like structure is innovatively prepared and used as LIB cathode material. By scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD) and electrochemical measurement, the structure and electrochemical performance of the as-synthesized FeF 3 /graphene composite are investigated. The results indicate that the sheet-like structure hybrid is formed by the FeF 3 nanosheets and the graphene sheets. Meantime, we demonstrate that the FeF 3 /graphene composite has good rate capability and cycling performance, whether it is based on conventional intercalation reaction or reversible conversion reactions. [ABSTRACT FROM AUTHOR]

The MnO 2 /ordered mesoporous carbon composites (MnO 2 /OMCs) with nanosized MnO 2 embedded in ordered mesoporous carbons are prepared by the redox reaction of KMnO 4 with ordered mesoporous carbon CMK-8 synthesized by KIT-6 as the hard template. The structure and morphology of the as-prepared MnO 2 /OMCs are characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm, Fourier infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results reveal that different MnO 2 contents are successfully introduced into the pores of CMK-8, and the obtained MnO 2 /OMCs can still maintain the ordered mesostructure and large specific surface area. The electrochemical properties of all the MnO 2 /OMCs samples are studied by cyclic voltammetry (CV), galvanostatic charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cycle life measurements in 6 mol L −1 KOH electrolyte. Due to the combination of the electrical double layer capacitance of CMK-8 and the redox pseudocapacitance of MnO 2 , the specific capacitance of the MnO 2 /OMC electrodes increases with the increase of the MnO 2 contents, and a maximum specific capacitance of 576.10 F g −1 at the scan rate of 1 mV s −1 can be achieved for MnO 2 /OMC-0.04. [ABSTRACT FROM AUTHOR]

Lithium-rich (Li-rich) cathode materials with different layered-spinel phase ratios are successfully synthesized by solvothermal and gradient calcination processes. The structure and electrochemical performances of the lithium-rich cathode materials with different layered-spinel phase ratios are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), high rate transmission electron microscopy (HRTEM), fast Fourier transformation (FFT) and electrochemical charge-discharge measurements. The results show that the calcination time and calcination temperature in gradient calcination processes jointly influence the phase ratios of the layered Li 2 MnO 3 and spinel Li 4 Mn 5 O 12 in the hybrid structure. Moreover, the spinel phase can lead to an excellent coulombic efficiency and cycle stability, while the layered phase will provide a high capacity. The materials with different layered-spinel phase ratios prepared in different gradient calcination processes show apparently different electrochemical performances, e.g., the maximum discharge capacity of the sample reaches 297 mAh/g at 0.1 C, it even exhibits high capacity retention of 90.6% after 200 cycles at 0.5 C. Furthermore, the temperatures at 750 and 800 °C are considered to be the suitable selection for the gradient calcination process. The spinel phase can profitably grow at 750 °C, and the layered phase is produced at 800 °C. [ABSTRACT FROM AUTHOR]

The structure design strategy for LRO based on the reversible anionic redox and spinel-layered coherent structure is propitious to maintaining high specific capacity and improving the reversible anionic redox and stable cyclic performance of LRO. [Display omitted] • LRO cathode with reversible anionic redox and spinel-layered coherent structure is designed. • The specific capacity and initial Coulombic efficiency are enhanced by the introduction of S-anions. • Stable interface structure and enhanced electrochemical kinetics are realized by the spinel-layered coherent structure. • Improved specific capacity and excellent cyclic stability are revealed in the modified LRO. Initiating effective strategies to improve the reversibility of anionic redox and structural stabilization is crucial to the development and industrial application of Li-rich cathode materials (LRO), which are regarded as the preferred option of the cathode materials for the next-generation lithium-ion battery with high energy density. To remit the unexpected behavior of structural destruction and capacity attenuation, this paper proposes a strategy for maintaining high specific capacity and improving the reversible anionic redox and stable cyclic performance of LRO by introducing the spinel-layered coherent structure and S-anions. Proved by the ex-situ X-ray photoelectron spectroscopy, S-anions can regulate the anionic redox reversibility and thus enhance the reversible discharge capacity and initial Coulombic efficiency. Moreover, the structural stability is greatly improved by the introduction of spinel-layered coherent structure and S-anions in LRO, which has been confirmed by abundant structural characterizations. Besides, the results reveal that the optimized material exhibits a high reversible discharge capacity of 289.52 mAh/g and good cyclic performance with a retention rate of 88.21% after 200 cycles. Evidently, the structure design strategy for LRO based on the reversible anionic redox and spinel-layered coherent structure is a significant exploration, which will bring a new clew for the design of the cathode materials with high-energy–density and excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

• Sandwich architecture of rGO-encapsulated Ni/Co co-doped FeF 3 ·0.33H 2 O was prepared. • Ni-doping facilitate mainly the capacity improvement by expanding the cell volume. • Co-doping enhance primarily the cycling stability by accelerating Li+ migration. • NC-FF are firmly encapsulated within rGO sheets by M O C bonding interaction. • NC-FF|Graphite full-cell shows a high reversible capacity and good cycle stability. Conversion-type iron fluoride promises a high energy density and redox potential, which is considered an extremely promising candidate for next-generation high-specific-energy and low-cost Li-ion battery. Unfortunately, its commercialization is plagued by the poor rate capability and fast capacity degradation resulting from its inferior electronic conductivity and large volumetric expansion. Herein, a three-dimensional sandwich architecture of rGO-encapsulated Ni/Co dual‐doped FeF 3 ·0.33H 2 O nanoparticles (NC-FF) is fabricated by co-precipitation and subsequent calcination. The results show that the flower-like Ni/Co dual‐doped FeF 3 ·0.33H 2 O nanoparticles are firmly encapsulated within highly conductive rGO sheets through M O C bonding interaction, which constructs a robust electronic/ionic network and a buffer layer against the severe volume variation. The Ni-doping can facilitate to the capacity improvement by expanding the cell volume, and the Co-doping can promote the rate capability and cycling stability enhancement by accelerating Li+ migration. Benefiting from the synergies of Ni/Co dual-doping and encapsulation of rGO, the NC-FF exhibits a high-rate capability of 200.1 mAh g−1 at 5.0 C and good cycle stability of 177.8 mAh g−1 after 400cycles. Moreover, the NC-FF|Graphite symmetric-cell still shows a high reversible capacity of 396.2 mAh g−1 at 1.0C and good cycle stability of 247.5 mAh g−1 after 100cycles. [ABSTRACT FROM AUTHOR]

• High-severity fire left significant legacy effects on multiple soil elements. • The average availability and stability of soil elements decreased after fire. • The associations amongst soil elements tended to be uncoupled at the SB site. • Soil CEC, ACP, CP and Aggr directly mediated soil multi-element coupling. • The nature of biogeochemical decoupling was attributed to fire and time. High-severity wildfires may lead to significant impacts on biogeochemical cycling both by burning biomass and by fire legacies. However, the legacy effects of wildfires on multiple soil element cycles across temporal trajectories have rarely been discussed. Here, we evaluated the availability and stability of seven essential soil elements and their stoichiometric ratios, as well as the coupling of multiple and individual elements, over more than two years in a half-mature, severely burnt (SB) artificial Pinus tabuliformis Carr. forest in North China (Beijing) in comparison with the unburnt (UB) control. Despite element concentrations jumped up and down remarkably during the first few months, results showed that the average availability and stability of all elements in soils of the SB site were lower than those of the UB site and legacy effects of fire were consistently significant on available nitrogen (N), phosphorus (P) and sodium. Temporal trajectories (months to years) varied amongst elements, and organic carbon (C) and N depleted more than other elements did. High levels (i.e. above the null model threshold) of multi-element coupling in soils of the UB site were maintained during our monitoring periods. By contrast, a reduction in the degree of element coupling was detected over time in soils of the SB site, which was concomitant with the core role of C and the great variability of P. Fire- and time-induced shifts in cation exchange capacity, acid phosphatase activity, capillary porosity and aggregate fraction dominated the uncoupling of multiple soil elements, implying the critical contributions of fire legacy effects and temporal variations. These responses have important implications for the consideration of additional long-term studies because such biogeochemical decoupling of elements may have unpredicted consequences under global change scenarios. Meanwhile, this work is helpful to predict the direction of ecosystem succession and to provide scientific evidence for management practices. [ABSTRACT FROM AUTHOR]

The Li-rich Li[NiMn]O microspheres are firstly prepared and subsequently transferred into the AlO-coated Li-rich Li[NiMn]O microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the AlO-coated Li-rich Li[NiMn]O sample has a typical α-NaFeO layered structure with the existence of LiMnO-type integrated component, and the AlO layer is uniformly coated on the surface of the spherical Li-rich Li[NiMn]O particles with a thickness of about 4 nm. Importantly, the AlO-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% AlO-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g at a rate of 0.1 C in the voltage of 2.0-4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% AlO-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% AlO-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g even at 10 C. Besides, the thin AlO layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li[NiMn]O. [ABSTRACT FROM AUTHOR]

Abstract: The LiFePO4/(C + La0.56Li0.33TiO3) composites with spherical morphology are synthesized for the first time via ammonia assisted hydrothermal method. The structure and electrochemical performance of LiFePO4/(C + La0.56Li0.33TiO3) are investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), charge/discharge tests and cyclic voltammetry (CV). It has been found that the hybrid coating layer composing of electron conductive C and fast Li ion conductive La0.56Li0.33TiO3 is synchronously deposited on the surface of LiFePO4 microspheres. The hybrid coating layer can be favourable for fast electron and Li+ transport, and avoid HF eroding LiFePO4 in electrolyte, thus improve the electrochemical performance. The initial discharge capacity of LiFePO4/(C + La0.56Li0.33TiO3) is 126.3 mAh g−1, the capacity retention is still as high as 98.3% even after 100 cycles at 5 C. Even at high rate of 30 C, it still reveals a high discharge capacity of 62.3 mAh g−1. [Copyright &y& Elsevier]

The irreversible evolution of oxygen for lithium-rich manganese-based cathode (LRMC) is the main challenge which will induce accelerated migration of transition metal ions and structural transformation, thus resulting in serious voltage attenuation and capacity decay. Herein, a facile and high-effective oxygen vacancy engineering of hydrogenation treatment is proposed for introducing oxygen vacancy on the surface of LRMC to suppress the irreversible evolution of oxygen. X-ray diffraction (XRD) Rietveld refinement, X-ray photoelectron spectroscopy and electron paramagnetic spectroscopy demonstrate the successful introduction of oxygen vacancy on the surface of LRMC. The changes of physicochemical properties of LRMC after hydrogenation treatment are investigated through systematical electrochemical performance tests and scanning electron microscopy and transmission electron microscopy. The investigative results reveal that the presence of oxygen vacancy can significantly improve the structural stability, electrical conductivity and Li+ diffusion kinetics of the LRMC materials. Especially, the optimized H500-LRMC shows excellent electrochemical performances including the enhanced cyclic stability with a capacity retention of 221.8 mAh g−1 and a capacity retention rate of 94.11% after 100 cycles. Therefore, the well-designed oxygen vacancy engineering through hydrogenation treatment is a promising strategy for the development and industrialization of the high-performance LRMC. • Oxygen vacancy (OV) is induced on the surface of LRMC by an efficient strategy. • OV endows LRMC with high structural stability and electron/ion conductivity. • The designed H500-LRMC cathode delivers a high electrochemical performance. • The mechanism of OV on improving the electrochemical property of LRMC is revealed. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Y2O3 coated LiMn2O4 microsphere wrapped with graphene is firstly synthesized. [•] The graphene/Y2O3/LiMn2O4 hybrid shows the notable rate and cycling performance. [•] Y2O3 and graphene modification can effectively improve the performance of material. [ABSTRACT FROM AUTHOR]

The YO nano-film is coated on the surface of the spherical spinel LiMnO by precipitation method and subsequent heat treatment at 550 °C for 5 h in air. The structure and performance of the bare LiMnO and YO-coated LiMnO are characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive analysis X-ray spectroscopy, galvanostatic charge-discharge, cyclic voltammetry, and impedance spectroscopy. It has been found that the addition of YO does not change the bulk structure of LiMnO, and the thickness of the YO coating layer is approximate to 3.0 nm. The 1 wt% YO-coated LiMnO electrode reveals excellent cycling performance with 80.3 % capacity retention after 500 cycles at 1 C at 25 °C. When cycling at elevated temperature 55 °C, the as-prepared sample still shows 76.7 % capacity retention after 500 cycles. These remarkable improvements indicate that thin YO coating on the surface of LiMnO is an effective way to improve the electrochemistry performance. Besides, the suppression of Mn dissolution into the electrolyte via the YO coating layer can be accounted for the improved performances. [ABSTRACT FROM AUTHOR]

Highlights: [•] BiPO4 is initially reported as a cathode material for lithium-ion batteries. [•] We have explored that BiPO4 is a cathode material based on conversion reactions. [•] Its theoretical specific capacity and output voltage are 264.5mAhg−1 and 3.14V. [•] Its theoretical volumetric energy density is close to twice higher than LiCoO2. [•] Effects of the phase transformation on electrochemistry of BiPO4 are discussed. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve the performance of the Li[Ni0.5Co0.2Mn0.3]O2, a novel spherical Li[Ni0.5Co0.2Mn0.3]O2–Li2MnO3 core–shell composite has been successfully synthesized by a simple sol–gel deposition method. It is found that the core–shell composite consists of Li[Ni0.5Co0.2Mn0.3]O2 as the core and Li2MnO3 as the outer shell according to examination by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDXS) and X-ray diffraction (XRD). The core–shell composite delivers a high capacity of 180.4 mAh g−1 at a rate of 0.1 C in the voltage range of 2.0–4.4 V. Most importantly, the core–shell composite exhibits excellent capacity retention of 98.8% after 200 cycles at a rate of 0.5 C, and 93.8% capacity retention after 100 cycles at a rate of 5 C at room temperature. When cycled at an elevated 55 °C, the prepared sample exhibits only 2.3% capacity loss after 100 cycles. Meanwhile, the core–shell composite shows significantly improved thermal stability relative to that of the pristine Li[Ni0.5Co0.2Mn0.3]O2. The improved stability of the core–shell composite is ascribed to the stable Li2MnO3 outer shell, which can prevent the Li[Ni0.5Co0.2Mn0.3]O2 core from direct contact with the electrolyte, and the core material could operate with no risk of structural disruption at high voltages and high temperatures. [Copyright &y& Elsevier]

Abstract: The pristine LiFePO4/C and Ni and Mn co-doping LiFe1−x−y Ni x Mn y PO4/C (x = 0.01–0.04; y = 0.04–0.01) composites are synthesized for the first time by a simple high-temperature solid-state route. The structure, morphology and electrochemical performance of the samples are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, scanning electron microscope (SEM), charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results indicate that the Ni and Mn co-doping does not destroy the olivine structure of LiFePO4, but it can stabilize the crystal structure, lengthen the Li–O bond, decrease charge transfer resistance, enhance Li ion diffusion velocity, and thus improve its cycling and high-rate capability of the LiFePO4/C. Especially, the LiFe0.95Ni0.02Mn0.03PO4/C shows the best cycling stability and rate capability among all the doped samples. The first discharge capacity of LiFe0.95Ni0.02Mn0.03PO4/C is 145.4 mAh g−1 with the capacity retention ratio of 98.6% till 100 cycles at 1C. Even at a high rate of 10C, it still reveals a high discharge capacity of 115.2 mAh g−1. [Copyright &y& Elsevier]

The activated nitrogen-enriched novel carbons (a-NENCs) have been prepared by direct carbonization of polyaniline/activated mesocarbon microbead composites and further activated by 16 M HNO. The electrochemical performances and supercapacitive behaviors of the a-NENCs in 6 M KOH, 1 M HSO, and 0.5 M KSO solutions are evaluated by cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance spectroscopy, cyclic life, leakage current, and self-discharge measurements. The results demonstrate that the supercapacitors perform definitely supercapacitive behaviors; especially in 6 M KOH electrolyte, the supercapacitor represents much better electrochemical performance with more excellent reversibility, shorter relaxation time of 1.11 s, and nearly ideal polarizability. The maximum specific capacitance of the supercapacitors using a-NENCs as active electrode material is 85.1 F g at a rate of 500 mA g in 6 M KOH. These outcomes indicate that the 6 M KOH aqueous solution is a promising electrolyte for the supercapacitor with a-NENCs as electrode material. [ABSTRACT FROM AUTHOR]

Abstract: Na and Ti co-doping Li1−x Na x Fe1−x Ti x PO4/C (x =0.00, 0.01, 0.03 and 0.05) composites were synthesized by a simple high-temperature solid-state method. The structure, morphology and electrochemical performance of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), charge/discharge tests, electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The results showed that the Na and Ti co-doped samples kept the olivine structure of LiFePO4, but Na and Ti co-doping can optimize the crystal microstructure, modify the particle morphology, decrease charge transfer resistance, enhance exchange current density, electrical conductivity and Li ion diffusion velocity, and thus improve the electrochemical performance of the LiFePO4/C. Among all the doped samples, Li0.97Na0.03Fe0.97Ti0.03PO4/C showed the best rate capability and cycling stability. The initial discharge capacity of Li0.97Na0.03Fe0.97Ti0.03PO4/C was 151.0mAhg−1 with the capacity retention ratio of 99.3% after 100 cycles at 1C. Especially, it still showed a high discharge capacity of over 97.3mAhg−1 even at a high rate of 20C. [Copyright &y& Elsevier]

Spinel LiMnO cathode materials were coated with 1.0, 3.0 and 5.0 wt.% of MgF by precipitation, followed by heat treatment at 400 °C for 5 h in air. The effects of MgF coating on the structural and electrochemical properties of LiMnO cathodes were investigated using XRD, SEM, and electrochemical tests. XRD and SEM results show that no significant bulk structural differences are observed between the coated and pristine LiMnO. The charge-discharge tests show that the discharge capacity of LiMnO decreases slightly, but the cyclability of LiMnO is clearly improved when the amount of the MgF coated was increased to 3.0 wt.%. The 3.0 wt.% MgF-coated LiMnO exhibits capacity retention of 80.1 and 76.7 % after 100 cycles at room temperature (25 °C) and elevated temperature (55 °C) at a rate of 1 C, respectively, much higher than those of the bare LiMnO (70.1 and 61.6 %). The improvement of electrochemical performance is attributed to the suppression of Mn dissolution into the electrolyte via the MgF coating layer. [ABSTRACT FROM AUTHOR]

Spherical Li[NiMnCo]O was prepared by both the continuous hydroxide co-precipitation method and continuous carbonate co-precipitation method under different calcined temperatures. The physical properties and electrochemical behaviors of Li[NiMnCo]O prepared by two methods were characterized by X-ray diffraction, scanning electron microscope, and electrochemical measurements. It has been found that different preparation methods will result in the differences in the morphology (shape, particle size, and tap density), structure stability, and the electrochemical characteristics (shape of initial charge/discharge curve, cycle stability, and rate capability) of the final product Li[NiMnCo]O. The physical and electrochemical properties of the spherical Li[NiMnCo]O prepared by continuous hydroxide co-precipitation is apparently superior to the one prepared by continuous carbonate co-precipitation method. The optimal sample prepared by continuous hydroxide co-precipitation at 820 °C exhibits a hexagonally ordered layer structure, high special discharge capacity, good capacity retention, and excellent rate capability. It delivers high initial discharge capacity of 175.2 mAh g at 0.2 C rate between 3.0 and 4.3 V, and the capacity retention of 98.8 % can be maintained after 50 cycles. While the voltage range is broadened up to 2.5 and 4.6 V vs. Li/Li, the special discharge capacities at 0.2 C, 0.5 C, 1 C, 2 C, 5 C, and 10 C rates are as high as 214.3, 205.0, 198.3, 183.3, 160.1 and 135.2 mAh g, respectively. [ABSTRACT FROM AUTHOR]