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Ameliorating the interfacial issues of the zinc anode, particularly dendrite growth and electrode corrosion, is imperative for rechargeable zinc metal batteries. Herein, an electrochemical-inert li...

Rechargeable aqueous zinc-ion batteries (ZIBs) are attractive candidates for next-generation batteries. However, the challenge of uneven zinc electroplating/electrostripping on bare Zn anodes has severely restrained the practical application of ZIBs. To address this problem, a straightforward strategy of sliver particle-coated zinc plate (designated as Zn@Ag) via the metallic replacement reaction as the zinc metal anode has been employed to facilitate uniform and stable Zn-plating/stripping. The newly formed AgZn3 alloy from silver particles at the first zinc-plating cycle with good zinc affinity can effectively lower the energy barrier of zinc nucleation and promote uniform electric field distribution for the flow of Zn ions, resulting in stable zinc deposition. Benefiting from the in situ formed alloy phase, the Zn@Ag anode achieves stable cycling for over 1700 h with a very low polarization voltage of about 21 mV at 0.25 mA cm−2 and 0.25 mA h cm−2, while the bare Zn anode just exhibits less than 150 cycles with large voltage fluctuation and polarization under same conditions. As a consequence, greatly improved performance of the Zn@Ag//CNT/MnO2 full-cell with twice the capacity (177 mA h g−1) than that of bare Zn//CNT/MnO2 full-cell (71 mA h g−1) after 400 cycles at 0.6 A g−1 can be realized. This work provides a facile and effective approach to regulate Zn deposition for the achievement of long-life rechargeable ZIBs.

The lithium metal anode has been treated as the most promising alternative in next-generation lithium-based batteries due to its ultra-high theoretical capacity, low potential and light weight. However, significant challenges such as dendrite growth and poor lifetime have severely hindered the commercialization process of lithium metal anodes. The separator not only functions as the first signal of lithium dendrite formation, but also the last barrier to prevent the battery from short-circuit, playing an irreplaceable role in lithium metal batteries. Traditional polyolefin separators have shortcomings such as poor thermal stability and poor wettability. Therefore, separator engineering is of great significance for suppressing lithium dendrite growth. In this review, we classified the recent progress of separator engineering in lithium metal batteries into four parts: (1) optimizing the performance of polyolefin membranes; (2) controlling the dendrite growth direction; (3) developing a novel separator material; (4) introducing a functional multilayer membrane. To obtain direct evidence of dendrite suppression by separator engineering, new technical means for certifying lithium deposition behaviors have also been reviewed. Finally, our conclusion and perspectives on the future research and development of lithium metal batteries are also briefly outlined.

All-solid-state batteries (ASSBs), particularly based on sulfide solid-state electrolytes (SSEs), are expected to meet the requirements of high-energy-density energy storage. However, the unstable interface between the ceramic pellets and lithium (Li) metal can induce unconstrained Li-dendrite growth with safety concerns. Herein, we design a carbon fluoride-silver (CF

Lithium-rich layered oxides (LLOs) are regarded as one of the most promising cathode materials for next generation Li-ion batteries (LIBs) due to their high energy density. However, the associated oxygen release and structure collapse resulting from the intrinsic anion and cation redox reactions lead to performance degradation, particularly the characteristic voltage fading which has prohibited the commercialization of LLOs for more than a decade. Herein, we have developed a dual-doping technique to overcome the longstanding structure and voltage instabilities of Co-free Li1.2Mn0.533Ni0.267O2, through the concurrent introduction of neodymium (Nd) and aluminum (Al) ions. Selective atomic substitution of Ni/Mn with Nd/Al ions and the preconstructed heteroepitaxial interface significantly enhance the voltage and capacity retention by regulating Ni ion activity and suppressing the phase transformation and Mn dissolution, thereby improving rate performance through tuning the electronic structure and promoting Li+ migration. The dual-doped material exhibits a superior cycling stability, with over 90% voltage retention and 82% capacity retention after 200 cycles, and excellent rate performance (150 mAh g−1 at 10 C).

Lithium-sulfur (Li-S) batteries are considered as a promising candidate of next generation lithium batteries by virtue of high theoretical energy density, low cost and eco-friendliness, yet their commercialization still suffers from undesirable polysulfide shuttling and uncontrollable Li dendrites growth. Herein, a dual-engineered separator is designed through double-side construction of ammonium alcohol polyvinyl phosphate/carbon black (AAPP/CB) constituted “polysulfide stockroom” and Li1.5Al0.5Ge1.5(PO4)3 (LAGP) based “ion guider” on a commercial polypropylene (PP) substrate. Such functional separator AAPP/CB@PP@LAGP enables highly robust, all-climate Li-S batteries, which is attributed to the efficient polysulfide-absorption/conversion function of the AAPP/CB layer and uniform Li ion distribution/transport capacity induced by the LAGP layer. It is anticipated that this work may provide a promising strategy for interface engineering of separators and promote the wide-temperature application of Li-S batteries.

The age softening phenomenon of the Li−B alloy was investigated by a series of tensile tests under various aging conditions. The results show that the tensile strength of the rolled Li−B alloy decreases with increasing aging time. Higher aging temperature accelerates the softening process, and leads to an early end of aging. A model was proposed to analyze the mechanism of the age softening. The vacancy annihilation is the control factor of age softening. The strength−temperature relationship was estimated by the newly proposed model and a standard heat treatment, annealing at 150 °C for 1 h, was designed to eliminate the age softening of rolled Li−B alloy.

Developing excellent pseudocapacitive electrodes with long cycle, high areal capacity and large rate has been challenged. 3D printing is an additive manufacture technique that has been explored to construct microelectrodes of arbitrary geometries for high-energy–density supercapacitors. In comparison with conventional electrodes with uncontrollable geometries and architectures, 3D-printed electrodes possess unique advantage in geometrical shape, mechanical properties, surface area, especially in ion transport and charge transfer. Thus, a desirable 3D electrode with ordered porous structures can be elaborately designed by 3D printing technology for improving electrochemical capacitance and rate capability. In this work, a designed, monolithic and ordered multi-porous 3D Cu conductive skeleton was manufactured through 3D direct ink writing technique and coated with CuO nanosheet arrays by an in situ electro-oxidation treatment. Benefiting from the highly ordered multi-porous nature, the 3D-structured skeleton can effectively enlarge the surface area, enhance the penetration of electrolyte and facilitate fast electron and ion transport. As a result, the 3D-printed Cu deposited with electro-oxidation-generated CuO (3DP Cu@CuO) electrodes demonstrates an ultrahigh areal capacitance of 1.690 F cm−2 (38.79 F cm−3) at a large current density of 30 mA cm−2 (688.59 mA cm−3), excellent lifespan of 88.20% capacitance retention after 10,000 cycles at 30 mA cm−2 and superior rate capability (94.31% retention, 2-30 mA cm−2). This design concept of 3D printing multi-porous current collector with hierarchical active materials provides a novel way to build high-performance 3D microelectrodes.

In this work, nickel/T-Nb2O5 nanoparticles encapsulated in mesoporous carbon nanofibers (denoted as Ni/T-Nb2O5@CNFs) are successfully prepared through a simple electrospinning route and succedent heating treatment. The presence of Ni in carbon nanofibers is beneficial for enhancing the electronic conductivity and the initial Coulombic efficiency. Ni/T-Nb2O5 nanoparticles are homogeneously incorporated in carbon nanofibers to form a nanocomposite system, which provides effective buffering during the lithiation/delithiation process for cycling stability. The Ni/T-Nb2O5@CNFs show high surface area (26.321 m2·g−1) and mesoporous microstructure, resulting in higher capacity and excellent rate performance. The Ni/T-Nb2O5@CNFs exhibit a remarkable capacity of 437 mAh·g−1 at a current density of 0.5 A·g−1 after 230 cycles and a capacity of 173 mAh·g−1 at a current density up to 10.0 A·g−1 after 1400 cycles. This work indicates that nickel/T-Nb2O5 nanoparticles encapsulated in carbon nanofibers can be a promising candidate for anode material in high-power LIBs.

Transition metal phosphides (TMPs) are recognized as such promising supercapacitor materials for the practical application, due to their superior electrical conductivity and excellent redox activity. Here, self-supported three-dimensional NiCoP nanoparticles embedded in NiCoO2 nanowires (NiCoO2/NiCoP) electrode consisting of nickel cobalt phosphides (NiCoP) with high activity and nickel cobalt oxides (NiCoO2) with good stability were fabricated by a hydrothermal and phosphorization method. The electrode integrates the advantages of nanowire arrays for fast ion transport and foam Ni for effective charge transport and flexibility. Benefitting the proper composition control of the nanohybrid and unique structure design, the optimized NiCoO2/NiCoP-20 exhibits a high specific capacitance of 3204 F·g−1 at 1 A·g−1 in 3 mol·L−1 KOH aqueous electrolyte in a three-electrode system. Moreover, the asymmetric supercapacitor assembled with the prepared NiCoO2/NiCoP-20 and activated carbon achieves a specific capacitance of 116 F·g−1 with a high energy density of 40.32 Wh·kg−1 at the power density of 800.18 W·kg−1. The practical application is further demonstrated with all-solid-state winding supercapacitor devices, with decent flexibility, in series to light the Central South University (CSU) logo consisting of 21 red LED indicators. The NiCoO2/NiCoP-20 combines the superior electrical conductivity and preeminent redox activity of NiCoP and excellent electrochemical stability of NiCoO2 together, which performed the best electrochemical performance.

The emerging inorganic CsPbI2Br perovskite is regarded as a promising candidate for future photovoltaics due to its superior photo-physical properties and thermal stability, but it usually requires a high fabrication temperature (>250 °C) and suffers from possible phase transition from a cubic α-phase to a non-perovskite δ-phase under ambient conditions, restricting its commercial applications. Herein, we demonstrated an additive-assisted hot solution spin coating route to simultaneously lower the fabrication temperature and stabilize the cubic phase structure. The incorporated biuret additive, consisting of functional amino and carbonyl groups, can strongly associate with the halide plumbates in the solution and generate optimal intermediate adducts of CsI–biuret–PbX2 to seed the large crystal growth, which can significantly reduce the perovskite formation energy and enable the low-temperature (120 °C) fabrication of α-phase CsPbI2Br. It was realized that the added biuret was mainly retained at the grain boundaries that effectively passivated antisite or under-coordinated defects, boosting the crystal quality with an improved photoluminescence quantum efficiency. In addition, the biuret molecules can act as anchors among the grains to stabilize the phase structure and prevent moisture permeation. As a result, a champion efficiency of 13.3% with improved ambient air stability was achieved in inverted all-inorganic perovskite solar cells, providing a cost-effective route to prepare high quality inorganic perovskites.

Understanding the complicated interplay of the continuously evolving electrode materials in their inherent 3D states during the battery operating condition is of great importance for advancing rechargeable battery research. In this regard, the synchrotron X-ray tomography technique, which enables non-destructive, multi-scale, and 3D imaging of a variety of electrode components before/during/after battery operation, becomes an essential tool to deepen this understanding. The past few years have witnessed an increasingly growing interest in applying this technique in battery research. Hence, it is time to not only summarize the already obtained battery-related knowledge by using this technique, but also to present a fundamental elucidation of this technique to boost future studies in battery research. To this end, this review firstly introduces the fundamental principles and experimental setups of the synchrotron X-ray tomography technique. After that, a user guide to its application in battery research and examples of its applications in research of various types of batteries are presented. The current review ends with a discussion of the future opportunities of this technique for next-generation rechargeable batteries research. It is expected that this review can enhance the reader's understanding of the synchrotron X-ray tomography technique and stimulate new ideas and opportunities in battery research.

Achieving non-dendritic Li deposition is generally believed to be a prerequisite for the successful commercialization of lithium metal batteries (LMBs). However, it is discussed here that eliminating the growth of the dendritic Li structure seems not to be sufficient to propel the LMB technology from laboratory research to practical applications. Other types of the electrochemically generated Li structure, besides the dendritic structure, must be further studied. It is suggested that considerable research effort be focused on studying the electrochemical nature of generated Li structures, in addition to finding novel strategies to eradicate them.

Lithium and oxygen activities can have substantial influences on the kinetics of ion and electron transport and the structural integrity of Li-rich layered oxide (LLO) cathodes, since reversible oxygen redox is ascribed to the extra capacity beyond the theoretical capacity from transition metal redox at high voltages. Herein, we demonstrate a liquid-solid interfacial reaction to generate a heteroepitaxial interface with tunable Li/O activities on LLOs using molten boric acid. The experimental and theoretical analyses indicate that the atomic scale interface is comprised of a disordered rock salt structure containing substantial Li/O vacancies along the layered structure, associated with a segregation tendency of Ni and Co. The formation of this heteroepitaxial interface with Li/O vacancies improves the ionic/electronic conduction and electrochemical/structural stability, leading to a high discharge capacity of 283 mA h g-1 with initial Coulombic efficiency of 91.7% (0.1 C, 2.0–4.7 V vs. Li+/Li), excellent rate performance (246 and 159.7 mAh g-1 at 1 C and 10 C, respectively) and enhanced cyclic performance with a capacity retention of 92% after 100 cycles. The findings highlight the importance of a well-engineered interface for the design of high performance layered cathode materials for Li storage.

Long-cycle-life and high-capacity nitrogen-doped carbon-coated α-MnSe nanofibers (α-MnSe/N-CNFs) electrodes were prepared by using an electrospinning process. The one-dimensional structural of α-MnSe/N-CNFs possesses great stability and play a key role in obtaining a long-cycle life for lithium-ion batteries. With nitrogen doping, improved pseudocapacitive behavior and conductivity were observed and the reversible capacity of the was increased to 956.3 mA h g−1 at 0.2 A g−1 after 200 cycles. The discharge capacity of α-MnSe/N-CNFs after 500 cycles reached 613.0 mA h g−1 even at a high current density of 1 A g−1. The excellent electrochemical performance of α-MnSe/N-CNFs holds great promise as a candidate anode material for high-performance lithium-ion batteries.

The constantly increasing demands on sustainable and high-performance energy storage devices generate tremendous research attentions on novel battery systems. Rechargeable magnesium battery (RMB), which possesses the advantages of low cost, natural abundance, has emerged as a considerable candidate. The fascinating features of high volumetric capacity, dendrites free and earth abundance also made it more fascinating. However, owing to the strong polarization of Mg ions, the existing electrodes and electrolyte cannot fully facilitate the Mg2+ ion insertion/extraction. In this regard, finding suitable electrode materials and electrolytes with high Mg insertion kinetics, excellent reversibility and costless are still the challenges that hinder the practical application of RMB. In this review, we mainly attempt to accumulate the recently advances in the development of electrodes, as well as development of advanced hybrid RMB systems. The review specifically aimed to provide new perspectives on the construction of novel electrode materials. Moreover, the challenges and perspective of RMBs are also discussed to highlight the limitations and the future direction. These may inspire more efforts on future work and accelerate the development process.

Low-cost Na-ion batteries (SIBs) are a promising alternative to Li-ion batteries (LIBs) for large-scale energy storage systems due to the abundant sodium resources and eco-friendliness. The volumetric changes of sodium anodes during the sodiation/desodiation processes, however, reduce the cycling life of Na-ion batteries. In order to solve the problem, we have used the electrospinning method to successfully fabricate mesoporous S/N-doped carbon nanofibers (S/N-C), which show a high capacity and high-rate capability in a Na-ion battery. The S/N-C nanofibers delivered a high reversible capacity of 552.5 and 355.3 mA h g−1 at 0.1 and 5 A g−1, respectively, because of the high S-doping (27.95%) in the carbon nanofibers. The introduction of N and S in S/N-C nanofibers increases the active sites for Na+ storage and reduces the energy required for Na+ transfer, as confirmed by in situ Raman spectroscopy and density functional theory (DFT) calculations. Moreover, the mesoporous S/N nanofibers are wetted by liquid electrolyte, which facilitates the Na+ transport and increases the rate performance, thus making them a suitable anode material for SIBs and other electrochemical energy storage devices.

Abrupt Li dendrite growth and the safety hazards caused by liquid electrolytes are generally acknowledged as major technical barriers for the practical application of Li metal batteries. Solid polymer electrolytes (SPEs) are promising to overcome these obstacles, but suffer from rigidity–conductivity inconsistency, ununiform ion distribution and inferior interfacial compatibility. Herein, an anion-immobilized SPE using vinylene carbonate as the rigid polymer backbone and flexible ether oxygen chains containing anion-trapping boron moieties is proposed, which facilitates the Li+ transport and adjusts the ion distribution. This ingenious design along with facile in situ preparation effectively integrates a favorable Young's modulus (2.41 GPa), high ionic conductivity (9.11 × 10−4 S cm−1 at 25 °C) and a high Li+ transference number (0.68), as well as achieving a stable solid electrolyte interface layer. As a result, these integrative properties enable dendrite-free LiFePO4/Li batteries with excellent rate capacity (8C, 98.3 mA h g−1) and superior long-term cyclability over 600 cycles at 30 °C, providing a new strategy for safe and high-energy all-solid-state energy storage systems.

Sodium-ion batteries (SIBs) hold great promise as power sources because of their low cost and decent electrochemical behavior. Nevertheless, the poor rate performance and long-term cycling capability of anode materials in SIBs still impede their practical application in smart grids and electric vehicles. Herein, we design a delicate method to embed WS2 nanosheets into lotus rhizome-like heteroatom-doped carbon nanofibers with abundant hierarchical tubes inside, forming WS2@sulfur and nitrogen-doped carbon nanofibers (WS2@S/N–C). The WS2@S/N–C nanofibers exhibit a large discharge capacity of 381 mA h g−1 at 100 mA g−1, excellent rate capacity of 108 mA h g−1 at 30 A g−1, and a superior capacity of 175 mA h g−1 at 5 A g−1 after 1000 cycles. The excellent performance of WS2@S/N–C is ascribed to the synergistic effects of WS2 nanosheets, contributing to larger interlayer spacing, and the stable lotus rhizome-like S/N–C nanofiber frameworks which alleviate the mechanical stress. Moreover, the WS2@S/N–C electrode shows obvious pseudocapacitive properties at 1 mV s−1 with a capacitive contribution of 86.5%. In addition, density functional theory calculations further indicate that the WS2@S/N–C electrode is very favorable for Na storage. This novel synthetic strategy is a promising method for synthesizing other electrode materials for rechargeable batteries in the future.

The inevitable formation of dendrite-like morphology restricts the practical application of metallic lithium (Li) in secondary lithium metal batteries (LMBs) though it is regarded as a promising anode material for high-energy-density batteries. Achieving uniform Li plating is an essential strategy to address this issue; nevertheless, it is difficult to realize this on a commercial current collector. Herein, a nanostructured lithiophilic layer of vertically aligned NiO hexagonal nanoplates on Ni foil is formed by a simple hydrothermal strategy. The lithiophilic nature of NiO can effectively guide the homogeneous smooth deposition of metallic Li on Ni collector surface by reducing the nucleation barrier of the electrode. Such a structure of vertical NiO nanoplate arrays transforming into Ni/Li2O greatly decreases the local current inhomogeneity, facilitates the Li-ion kinetic transfer, and ensures good electron conduction between the lithiophilic layer and the conductive substrate. Benefiting from such a structure, the fabricated anode achieves a steady coulombic efficiency of 97% for 140 cycles (1 mA cm−2) and a prolonged lifespan of up to 600 hours (0.25 mA cm−2), confirming the effective suppression of volume change and dendrite morphology. This strategy provides an effective and facile way for obtaining a stable lithium metal anode.

Nano energy 82, 105762 (1-5) (2021). doi:10.1016/j.nanoen.2021.105762, From non-destructive and cross-sectional visualization by synchrotron X-ray tomography, we suggest a novel capacity decaying mechanism of all-solid-state Na batteries built with closo-borate electrolytes caused by electrochemically generated inactive Na electrodeposits., Published by Elsevier, Amsterdam [u.a.]

Lithium-rich, manganese-based layered oxides are considered one of the most valuable cathode materials for the next generation of high-energy density lithium-ion batteries (LIBs) for their high specific capacity and low cost. However, their practical implementation in LIBs is hindered by the rapid voltage/capacity decay on cycling and the long-standing contradictions between redox kinetics and volumetric energy density due to their poor calendaring compatibility. Herein, a coherent near-zero-strain interphase is constructed on the grain boundaries of cathode secondary particles by infusing LiAlO2 material through the reactive infiltration method (RIM). Theoretical calculations, multi-scale characterizations, and electrochemical tests show that this coherent interphase with near-zero-strain feature upon electrochemical (de)lithiation inhibits volume changes of the lattice and structural degradation of cathode primary particles during cycling. More importantly, the ionically conductive LiAlO2 nanolayer infiltrated in the grain boundaries of cathode secondary particles can not only promote the rapid Li+ migration and act as a barrier to protect the material from the corrosion of the electrolyte but also effectively improve the mechanical strength of the cathode secondary particles. Collectedly, the LiAlO2-infiltrated cathode materials display superior electrochemical cyclability, enhanced rate capability, and industrial calendaring performance, marking a significant step toward commercial implementation.

Aqueous rechargeable Zn metal batteries have attracted widespread attention due to the intrinsic high volumetric capacity, low cost, and high safety. However, the low Coulombic efficiency and limited lifespan of Zn metal anodes resulting from uncontrollable growth of Zn dendrites impede their practical application. In this work, a 3D interconnected ZnF

Although a great variety of strategies to suppress Li dendrite have been proposed for lithium metal batteries (LMBs), a deeper understanding of the factors playing a crucial role during extended el...

High energy density lithium metal batteries (LMBs) are promising next‐generation energy storage devices. However, the uncontrollable dendrite growth and huge volume change limit their practical applications. Here, a new Mg doped Li–LiB alloy with in situ formed lithiophilic 3D LiB skeleton (hereinafter called Li–B–Mg composite) is presented to suppress Li dendrite and mitigate volume change. The LiB skeleton exhibits superior lithiophilic and conductive characteristics, which contributes to the reduction of the local current density and homogenization of incoming Li+ flux. With the introduction of Mg, the composite achieves an ultralong lithium deposition/dissolution lifespan (500 h, at 0.5 mA cm−2) without short circuit in the symmetrical battery. In addition, the electrochemical performance is superior in full batteries assembled with LiCoO2 cathode and the manufactured composite. The currently proposed 3D Li–B–Mg composite anode may significantly propel the advancement of LMB technology from laboratory research to industrial commercialization., A Li–B–Mg composite with in situ formed 3D LiB fiber network shows a dendrite‐free morphology and less volume change during cycling. The symmetrical battery achieves a long and stable cycle lifespan of more than 500 h at 0.5 mA cm−2 due to the effect of skeleton and the addition of Mg. The full battery also displays improved electrochemical performance.

The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.

Nickel-rich layered oxides (NLOs) exhibit great potential to meet the ever-growing demand for further increases in the energy density of Li-ion batteries because of their high specific capacities. However, NLOs usually suffer from severe structural degradation and undesired side reactions when cycled above 4.3 V. These effects are strongly correlated with the surface structure and chemistry of the active NLO materials. Herein, we demonstrate a preformed cation-mixed ( Fm3 m) surface nanolayer (∼5 nm) that shares a consistent oxygen framework with the layered lattice through Zr modification, in which Ni cations reside in Li slabs and play the role of a "pillar". This preformed nanolayer alleviates the detrimental phase transformations upon electrochemical cycling, effectively enhancing the structural stability. As a result, the Zr-modified Li(Ni0.8Co0.1Mn0.1)0.985Zr0.015O2 material exhibits a high reversible discharge capacity of ∼210 mA h/g at 0.1 C (1 C = 200 mA/g) and outstanding cycling stability with a capacity retention of 93.2% after 100 cycles between 2.8 and 4.5 V. This strategy may be further extended to design and prepare other high-performance layered oxide cathode materials.

Li2MnSiO4-based cathode materials possess reasonable work potentials and high theoretical capacities, while the practical energy/power densities are constrained by their inferior kinetics of Li+ diffusion. In this work, the Pmn21-structure Li2FexMn1-xSiO4/C materials were synthesized via a solvothermal method and evaluated as Li-ion cathode materials, with notable morphological evolutions and tunable crystallographic habits observed after solvothermal process. The Li2Fe0.33Mn0.67SiO4/C material delivers an initial reversible capacity of 250.2 mAh g−1 at 0.1 C (~ 1.51 Li+ insertion/extraction, 1 C = 166 mA g−1), excellent high-rate capability (52.2 mAh g−1 at 5 C), and good long-term cyclability (64.6% after 196 cycles at 2 C). The enhanced electrochemical properties are attributed to the boosted ion/electron transports induced by preferred morphological and structural characteristics of Li2Fe0.33Mn0.67SiO4/C. Keywords: Electrochemistry, Silicates, Nanostructures, Enhanced kinetics, Li-ion battery

Li2TMSiO4 (TM = Mn, Fe, Co, etc.) is regarded as a new class of cathode materials for next generation Li-ion batteries because of the theoretical possibility of reversible deintercalation of two Li ions from the structure (ca. 330 mA hg−1). Nevertheless, the silicate cathode still suffers from low electronic conductivity, slow Li ion diffusion and structural instability upon deep cycling. To solve these problems, for the first time, we propose a rational design of mesocrystalline Li2FeSiO4 hollow discoids with an ordered single-crystal-like structure and highly exposed (001) facets. The Li2FeSiO4 mesocrystals display a near theoretical discharge capacity, superior rate capability and good cycling stability. The enhanced Li storage performance is ascribed to the unique structural features with a large surface area generated from the hollow mesocrystal structure and a shortened Li+ diffusion path along (001) exposed facets. This new facile, elegant synthesis method that enables the manipulation of crystal growth and subsequent improvements in the electronic and ionic kinetics and structural integrity should have a positive impact on the research and development of silicate materials as promising cathodes for next generation Li-ion batteries.

In recent years, porous colloidal particles have found promising applications in catalytic fields, such as photocatalysis, electrocatalysis, industrial and automotive byproducts removal, as well as biomass upgrading. These applications are critical for alleviating the energy crisis and environmental pollution. Porous colloidal particles have remarkable specific areas and abundant reactive sites, which can significantly improve the mass/charge transport and reaction rate in catalysis. Precursor-based synthesis is among the most facile and widely-adopted methods to achieve monodisperse and homogeneous porous colloidal particles. In the current review, we briefly introduce the general catalytic applications of porous colloidal particles. The conventional precursor-based methods are reviewed to design state-of-the-art porous colloidal particles as highly efficient catalysts. The recent development of porous colloidal particles derived from metal-organic frameworks (MOFs), glycerates, carbonate precursors, and ion exchange methods are reviewed. In the end, the current concerns and future development of porous colloidal particles are outlined.

Limited ionic conduction and poor solid/solid interfacial stability are crucial characteristics that impede the practical application of solid polymeric electrolytes. Herein, a star-shaped solid composite electrolyte (SCE) containing multifunctional components, including anion-trapping boron moieties (B-PEGMA), poly(ethylene glycol)methyl ether methacrylate (PEGMEM) and octavinyl octasilsesquioxane (OV-POSS) nanofiller, was developed via a simple free radical polymerization method. The unique star-shaped structure induced by OV-POSS is beneficial to increasing the movement of polymer chains and forming continuously interconnected ion-conducting channels and the boron moieties can promote lithium salt dissociation and increase the effective transmission of Li+ in the electrolyte. This SCE exhibits an extremely high ionic conductivity of 3.44 × 10−4 S cm−1 and a high Li ion transference number of 0.58 at 25 °C, as well as excellent interfacial compatibility with the Li electrode leading to excellent rate performance and good cyclic stability in all-solid-state Li batteries.

Despite being considered as a promising candidate for cathode of next-generation batteries, sodium manganese orthosilicate suffers from sluggish kinetics, while no effective enhancement through structural manipulation has been reported yet. Herein a three-dimensionally ordered macroporous Na2MnSiO4/C is fabricated via a templated sol-gel method and investigated as a cathode material for sodium ion batteries. It delivers a high initial reversible capacity of 207 mAh g−1 (∼1.5 mol of Na+ insertion/extraction) at 0.1 C (1C = 139 mAh g−1), excellent high-rate capability (76 mAh g−1 at 5 C) and long-term cyclability (76.0% after 345 cycles at 2 C). The superior electrochemical properties are ascribed to short Na-ion diffusion path of honeycomb-like 3D ordered macroporous structure, fast electron transportation of interconnected carbon frameworks and effective constraint of volumetric changes upon electrochemical cycling. The rational design of 3D ordered porous structure may facilitate the development of silicate-based cathode materials that have problems of low electronic conductivity, slow ion diffusion and structural instability for new high-energy sodium ion batteries.

Limited practical capacity and poor cyclability caused by sluggish kinetics and structural instability are essential aspects that constrain the potential application of Li2MnSiO4 cathode materials. Herein, Li2Mn1–xCaxSiO4/C nanoplates are synthesized using a diethylene-glycol-assisted solvothermal method, targeting to circumvent its drawbacks. Compared with the pristine material, the Ca-substituted material exhibits enhanced electrochemical kinetics and improved cycle life performance. In combination with experimental studies and first-principles calculations, we reveal that Ca incorporation enhances electronic conductivity and the Li-ion diffusion coefficient of the Ca-substituted material, and it improves the structural stability by reducing the lattice distortion. It also shrinks the crystal size and alleviates structure collapse to enhance cycling performance. It is demonstrated that Ca can alleviate the two detrimental factors and shed lights on the further searching for suitable dopants.

Li2MnSiO4 has attracted significant attention as a cathode material for lithium ion batteries because of its high theoretical capacity (330 mA h g–1 with two Li+ ions per formula unit), low cost, and environmentally friendly nature. However, its intrinsically poor Li diffusion, low electronic conductivity, and structural instability preclude its use in practical applications. Herein, elongated hexagonal prism-shaped Li2MnSiO4 nanoplates with preferentially exposed {001} and {210} facets have been successfully synthesized via a solvothermal method. Density functional theory calculations and experimental characterization reveal that the formation mechanism involves the decomposition of solid precursors to nanosheets, self-assembly into nanoplates, and Ostwald ripening. Hydroxyl-containing solvents such as ethylene glycol and diethylene glycol play a crucial role as capping agents in tuning the preferential growth. Li2MnSiO4@C nanoplates demonstrate a near theoretical discharge capacity of 326.7 mA h g–1 at ...