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The impact of tropical Pacific sea surface temperature (SST) biases on the deterministic skill of the Unified Forecast System (UFS) coupled model Prototype 5 is evaluated during weeks 1–4 of the forecast. The evaluation is limited to the contiguous United States (CONUS) and two seasons: boreal summer (June–September) and winter (December–March). The tropical SST in the UFS model is warmer than in observations and bias patterns show seasonal dependence especially in the central and western Pacific. During boreal summer, the bias is located north of the equator whereas in winter, the bias is located in the Southern Hemisphere. A regression analysis indicates a significant relationship between these SST biases and the biases in the surface temperature and precipitation over the CONUS along with midtroposphere large-scale circulation and North Pacific storm-track activity. The SST biases affect the biases in other fields from week 1 of the forecast and the impact becomes stronger as the lead time increases to week 4. The impact of SST biases on the biases in other fields show a qualitative relationship to the patterns of forecast errors of the fields.

This work investigates the impact of tropical sea surface temperature (SST) biases on the subseasonal to seasonal (S2S) precipitation forecast skill over the Contiguous United States (CONUS) in the Unified Forecast System (UFS) coupled model Prototype 6. Boreal summer (June - September) and winter (December - March) for 2011-2018 were analyzed. The impact of tropical West Pacific (WP) and tropical North Atlantic (TNA) warm SST biases is evaluated using multivariate linear regression analysis. A warm SST bias over the WP influences the CONUS precipitation remotely through a Rossby wave-train in both seasons. During boreal winter, a warm SST bias over the TNA partly affects the magnitude of the North Atlantic Subtropical High (NASH)’s center, which in the reforecasts is weaker than in reanalysis. The weaker NASH favors an enhanced moisture transport from the Gulf of Mexico, leading to increased precipitation over the southeast U. S. Compared to reanalysis, during boreal summer, the NASH’s center is also weaker and in addition, its position is displaced to the northeast. The displacement further affects the CONUS summer precipitation. The SST biases over the two tropical regions and their impact become stronger as the forecast lead increases from week 1 to 4. These tropical biases explain up to 10% of the CONUS precipitation biases on the S2S time scale.

To improve NOAA’s seasonal forecasting capabilities, a new coupled system within the Unified Forecast System (UFS) framework is being developed through a community-wide effort led by NOAA’s Environmental Modeling Center targeting the configuration of a future operational Seasonal Forecast System (SFS v1). An experimental version of this ensemble seasonal forecasting system is tested on forecasting the strong El Niño of 2015/16. The then-operational systems and NCEP real-time seasonal forecasts (CFSv2) underestimated its strength towards the end of 2015 and beginning of 2016. In addition to perturbing the atmospheric initial conditions, run-time stochastic physics-based perturbations are applied in both atmosphere and ocean components of this new coupled system to represent the model uncertainties. The UFS ensembles are initialized on June 1st, 2015 and run through a 9-month period. Compared to CFSv2, the forecast of Niño 3.4 SST and intra-seasonal zonal windstress for the 2015/16 El Niño in the UFS system are improved, as is the ensemble spread. A cold SST forecast error develops in the central equatorial Pacific, likely from excess evaporative cooling, shallower thermocline, and an excessively strong vertical current shear driven cooling. Near the eastern equatorial Pacific coast, on the other hand, warm surface and cool subsurface errors persist from initialization until the end of the forecast. The results suggest that further improvement in the seasonal forecast may be achieved by a combination of factors, including, but not limited to, improving the coupled system initialization, along with the atmospheric physics.

In the rising advent of organic Li-ion positive electrode materials with increased energy content, chemistries with high redox potential and intrinsic oxidation stability, while in the lithium containing (Li-ion) form, remain a challenge. Molecular engineering of carbonyl compounds and of conjugated sulfonamide chemistries, have provided ground for future developments, while also inciting the search for other organic chemistry functions or classes, with alike properties, and with further improved energy storage metrics. Herein, we report on the solid- phase reversible electrochemistry of a new class of organic redox functionality for batteries, the lithium salts of conjugated oximates. The disclosed first five examples of the oximate class, including cyclic (aromatic), and acyclic (non-aromatic), as well as aliphatic and tetra-functional stereotypes, uncover the complex interplay between the molecular structure and the electroactivity, as well as the potential of this rich family as Li-ion positive electrode materials for batteries. Amongst the exotic features specific to this class of materials, the most appealing one is the reversible electrochemical polymerization – depolymerization accompanying the charge storage process in solid phase, through intermolecular azodioxy coupling (-ONNO-) or the intramolecular furoxan cyclization of the oxidized forms. Over the disclosed materials, the best performing candidate delivers a high reversible capacity of 350 mAh g-1 at an average potential of 3.0 vs. Li+/Li0, attaining 1 kWh kg-1 specific energy content at the material level metric. This work ascertains a strong link between the electrochemistry, organic chemistry and battery science by emphasizing on how different phases, mechanisms and performances can be accessed using a single chemical functionality.

In the rising advent of organic Li-ion positive electrode materials with increased energy content, chemistries with high redox potential and intrinsic oxidation stability remain a challenge. Here, we report the solid-phase reversible electrochemistry of the oximate organic redox functionality. The disclosed oximate chemistries, including cyclic, acyclic, aliphatic, and tetra-functional stereotypes, uncover the complex interplay between the molecular structure and the electroactivity. Among the exotic features, the most appealing one is the reversible electrochemical polymerization accompanying the charge storage process in solid phase, through intermolecular azodioxy bond coupling. The best-performing oximate delivers a high reversible capacity of 350 mAh g −1 at an average potential of 3.0 versus Li + /Li 0 , attaining 1 kWh kg −1 specific energy content at the material level metric. This work ascertains a strong link between electrochemistry, organic chemistry, and battery science by emphasizing on how different phases, mechanisms, and performances can be accessed using a single chemical functionality.

Phase change material (PCM) can utilize different thermal storage modes to improve the efficiency of electric heating loads. Traditionally, PCM-based electric heating equipment is controlled by users respectively. There is a lack of interaction between the PCM-based electric heating equipment and the power dispatch company. The hierarchical optimal control strategy for electric heating load is proposed in this paper to deal with the problem. Firstly, based on the LSTM algorithm, the energy consumption characteristics of PCM-based electric heating are analyzed, and the load power of PCM-based electric heating is predicted, then the two-layer optimal electric heating loads control model is investigated with phase change thermal storage modes. The upper layer model is developed to minimize the cost of a comprehensive load dispatching scheme, and the lower layer model is aimed at minimizing the cost during peak and valley periods. Under different types of electric heating response, thermal storage response is designed to examine the electric heating load optimal control strategy. Finally, a typical example is used to verify the application of the two-layer optimal control strategy of the PCM-based electric heating loads. The technical method can effectively improve the thermal and electric conversion efficiency.

Metal–organic frameworks (MOFs) have emerged as an important, yet highly challenging class of electrochemical energy storage materials. The chemical principles for electroactive MOFs remain, however, poorly explored because precise chemical and structural control is mandatory. For instance, no anionic MOF with a lithium cation reservoir and reversible redox (like a conventional Li-ion cathode) has been synthesized to date. Herein, we report on electrically conducting Li-ion MOF cathodes with the generic formula Li2-M-DOBDC (wherein M = Mg2+ or Mn2+; DOBDC4– = 2,5-dioxido-1,4-benzenedicarboxylate), by rational control of the ligand to transition metal stoichiometry and secondary building unit (SBU) topology in the archetypal CPO-27. The accurate chemical and structural changes not only enable reversible redox but also induce a million-fold electrical conductivity increase by virtue of efficient electronic self-exchange facilitated by mix-in redox: 10–7 S/cm for Li2-Mn-DOBDC vs 10–13 S/cm for the isoreticular H2-Mn-DOBDC and Li2-Mg-DOBDC, or the Mn-CPO-27 compositional analogues. This particular SBU topology also considerably augments the redox potential of the DOBDC4– linker (from 2.4 V up to 3.2 V, vs Li+/Li0), a highly practical feature for Li-ion battery assembly and energy evaluation. As a particular cathode material, Li2-Mn-DOBDC displays an average discharge potential of 3.2 V vs Li+/Li0, demonstrates excellent capacity retention over 100 cycles, while also handling fast cycling rates, inherent to the intrinsic electronic conductivity. The Li2-M-DOBDC material validates the concept of reversible redox activity and electronic conductivity in MOFs by accommodating the ligand’s noncoordinating redox center through composition and SBU design.

In this study, a series of ocean observing system simulation experiments (OSSEs) are conducted in support of the tropical Pacific observing system (TPOS) 2020 Project (TPOS 2020) which was established in 2014, with aims to develop a more sustainable and resilient observing system for the tropical Pacific. The experiments are based on an ocean data assimilation system that is under development at the Joint Center for Satellite Data Assimilation (JCSDA) and the Environmental Modeling Center (EMC)/National Centers for Environmental Prediction (NCEP). The atmospheric forcing and synthetic ocean observations are generated from a nature run, which is based on a modified CFSv2 with a vertical ocean resolution of 1-meter near the ocean surface. To explore the efficacy of TAO/TRITON and Argo observations in TPOS, synthetic ocean temperature and salinity observations were constructed by sampling the nature run following their present distributions. Our experiments include a free run with no “observations” assimilated, and assimilation runs with the TAO/TRITON and Argo synthetic observations assimilated separately or jointly. These experiments were analyzed by comparing their long-term mean states and variabilities at different time scales [i.e., low-frequency (>90 days), intraseasonal (20~90 days), and high-frequency (

The predictability of the Unified Forecast System (UFS) Coupled Model Prototype 2 developed by the National Centers for Environmental Prediction is assessed for the boreal summer over the continental United States (CONUS). The retrospective forecasts of low-level horizontal wind, precipitation and 2-m temperature for 2011–17 are examined to determine the predictability at subseasonal time scale. Using a data-adaptive method, the leading modes of variability are obtained and identified to be related to El Niño–Southern Oscillation (ENSO), intraseasonal oscillation (ISO), and warming trend. In a new approach, the sources of enhanced predictability are identified by examining the forecast errors and correlations in the weekly averages of the leading modes of variability. During the boreal summer, the ISO followed by the trend in UFS are found to provide better predictability in weeks 1–4 compared to the ENSO mode and the total anomaly. The western CONUS seems to have better predictability on weekly time scale in all three modes.

Sodium and iron make up the perfect combination for the growing demand for sustainable energy storage systems, given the natural abundance and sustainability of the two building block elements. However, most sodium-iron electrode chemistries are plagued by intrinsic low energy densities with continuous ongoing efforts to solve this. Herein, the chemical space of a series of (meta)stable, off-stoichiometric Fe-PO

In the rising advent of organic Li-ion cathodes with practical characteristic of being air-stable while in the reduced lithium-reservoir form, we report herein a new class of organic Li-ion positive electrode materials - the conjugated oximate lithium salts. The solid-phase electrochemistry of first five examples of the oximate class, including cyclic (aromatic), acyclic (non-aromatic), aliphatic and tetra-functional stereotypes, uncovers the complex interplay between the molecular structure and the electroactivity in the solid phase, as well as the potential of this rich family as cathode materials for lithium-ion batteries. The conjugation of oximate functions within the molecular core is found to endow excellent air stability of lithiated reduced phases, an important prerequisite for practical use as Li-ion positive electrode materials. Amongst the exotic features characterizing the solid-state electrochemistry of this class of materials, the most appealing one belongs to the reversible solid-state polymerization through intermolecular azodioxy coupling (-ONNO-) and the intramolecular furoxan cyclization of their oxidized forms. In the disclosed series of materials, the best performing candidate delivers high reversible capacity of 357 at an average potential of 3.0 vs. Li+/Li0, attaining over 1 KWh kg-1 specific energy content.

An interesting activation phenomenon: Activation with cycling of a 3.8 V (vs. Na+/Na) redox process in the iron-rich Na0.6Fe1.2PO4 material unlocks new electrochemical mechanism for high-performance, low-cost and eco-friendly Na-ion cathodes

Doping carbonaceous materials are regarded as prospective cathode candidates for high-performance lithium-sulfur (Li−S) batteries. In this study, we construct a dual functional modification system, including iodine-doped soft carbon (I-SC) and iodine functional separator for Li−S batteries. The formation of C−I bonds in the carbon skeleton increases the carbon interlayer spacing and displays a powerful chemical adsorption ability and electrocatalytic activity for polysulfide conversion. In addition, semi-hollow micro-rods-structure soft carbon not only accommodates the volume expansion of sulfur, but also provides a continuous conductive network to transport Li+ and electrons over cycling. Furthermore, by assisting with polyiodide (e. g., I3− and I5−) modified separator, the polysulfide migration can be further controlled, resulting in a high capacity of 956 mAh g−1 at 0.2 C after 300 cycles. This work represents the importance of I-doping and provides the potential of soft carbon for low-cost and scalable fabrication of energy storage systems.

Sodium and iron make up the perfect combination for the growing demand for sustainable energy storage systems, given the natural abundance and sustainability of the two building block elements. However, most sodium–iron electrode chemistries are plagued by intrinsic low energy densities with continuous ongoing efforts to solve this. Herein, the chemical space of a series of (meta)stable, off-stoichiometric Fe-PO4-F phases is analyzed. Some are found to display markedly improved electrochemical activity for sodium storage, as compared to the amorphous or thermodynamically stable phases of equivalent composition. The metastable crystalline Na1.2Fe1.2PO4F0.6 delivers a reversible capacity of more than 140 mAh g−1 with an average discharge potential of 2.9 V (vs Na+/Na0) resulting in a practical specific energy density of 400 Wh kg−1 (estimated at the material level), outperforming many developed Fe-PO4 analogs thus far, with further multiple possibilities to be explored toward improved energy storage metrics. Overall, this study unlocks the possibilities of off-stoichiometric Fe-PO4-F cathode materials and reveals the importance to explore the oft-overlooked metastable or transient state materials for energy storage.

Coordination polymers (CPs) made of redox-active organic moieties and metal ions emerge as an important class of electroactive materials for battery applications. However, the design and synthesis of high voltage alkali-cation reservoir anionic CPs remains challenging, hindering their practical applications. Herein, we report a family of electrically conducting alkali-cation reservoir CPs with the general formula of A2-TM-PTtSA (wherein A = Li+, Na+, or K+; TM = Fe2+, Co2+, or Mn2+; and PTtSA = benzene-1,2,4,5-tetra-methylsulfonamide). The incorporation of transition metal centers not only enables intrinsic high electrical conductivity, but also shows an impressive redox potential increase of as high as 1 V as compared to A4-PTtSA analogues, resulting in a class of organometallic cathode materials with a high average redox potential of 2.95–3.25 V for Li-, Na- and K-ion batteries. A detailed structure – composition – physicochemical properties – performance correlation study is provided relying on experimental and computational analysis. The best performing candidate shows excellent rate capability (86% of the nominal capacity retained at 10C rate), remarkable cycling stability (96.5% after 1000 cycles), outstanding tolerance to low carbon content (5 wt%), high mass loading (50 mg cm−2), and extreme utilisation conditions of low earth orbit space environment tests. The significance of the disclosed alkali-ion reservoir cathodes is further emphasized by utilizing conventional Li-host graphite anode for full cell assembly, attaining a record voltage of 3 V in an organic cathode Li-ion proof-of-concept cell.

Background: The anti-thrombotic strategy for patients with atrial fibrillation (AF) who have undergone percutaneous coronary intervention (PCI) for coronary artery disease (CAD) is a common and difficult challenge. This pilot study aimed to assess the feasibility and safety of “one-stop” left atrial appendage closure (LAAC) combined with PCI as an alternative stroke prophylaxis strategy. Methods: From March 2017 to October 2019, AF patients with elevated bleeding risk and significant stable CAD requiring PCI were recruited to undergo LAAC as alternative stroke prophylaxis in Fuwai Hospital, Beijing, China. LAAC was performed either in the same setting with PCI (i.e. “one-stop” LAAC/PCI), or as staged procedure after PCI. Dual antiplatelet therapy was given for all patients after LAAC. Peri-procedural and intermediate-term clinical outcomes were assessed through hospital clinical records review and standardized telephone interviews. Results: A total of 24 patients were recruited including 13 (54.2%) underwent stage procedure and 11 (45.8%) underwent “one-stop” procedure respectively. The mean CHA(2)DS(2)-VASc and HAS-BLED scores were 4.5±1.4 and 3 (IQR 3,4) respectively. Six patients (46.1%) in the staged procedure cohort were treated with triple anti-thrombotic following PCI, with 2 developed minor bleeding before LAAC. One patient (“one-stop” cohort) had gastrointestinal bleeding 1 day after procedure. Otherwise, there was no device related complication or peri-procedural stroke/myocardial infarction. After a mean 19±5.4 months follow-up, there was no death, myocardial infarction, stroke and systemic embolization detected. Conclusions: In this pilot study, “one-stop” LAAC with PCI was shown to be efficacious with no stroke, MI, VARC-2 major bleeding or CV death reported over a mean follow-up of 19 months, and safe with no major peri-procedural bleeding or device related complications.

The powertrain system is critical to the reliability of a battery electric vehicle (BEV). However, the BEV powertrain is a complex system, it includes the motor, motor controller, power distribution unit, battery system, etc. The failure of any of these components may result in the failure of the entire powertrain system and eventually cause serious traffic accidents on the road. However, how much does each component affect the reliability of the entire system, and which components are the most vulnerable in the entire system? These questions are still unanswered today. To develop a reliability design for a BEV powertrain system, it is essential to conduct detailed research by investigating the most vulnerable component parts of the entire powertrain. In the present study, a fault-tree model of the entire powertrain and its subsystems was developed. Based on this model, the failure rates of all components were calculated first. Then, trends in the reliability indices for the entire powertrain and its components were estimated against BEV service life. From the estimation results, we learned that with increased service time, the reliability of the entire powertrain system is indeed much lower than that of its individual subsystems. Moreover, through comparative research, we found that the battery module is the most unreliable component not only of the battery system, but the entire powertrain system. Additionally, it was interesting to find that the reliability of the motor components was higher than that of other subsystem components, but that the reliability indices for the entire motor were not the highest among all the powertrain subsystems studied in this paper. We believe the findings of the present study will be of great significance to an improved understanding of the reliability design and maintenance of BEVs.

New solid polymer electrolytes are of particular interest for next-generation high-energy batteries since they can overcome the limited voltage window of conventional polyether-based electrolytes. Herein, a flame-retardant phosphorus-containing polymer, poly(dimethyl(methacryloyloxy)methyl phosphonate) (PMAPC1) is introduced as a promising polymer matrix. Free-standing membranes are easily obtained by mixing PMAPC1 with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and a small amount of acetonitrile (AN). LiTFSI/AN mixed aggregates are formed that act as plasticizers and enable ionic conductivities up to 1.6 × 10-3 S cm-1 at 100 °C. The high content of LiTFSI used in our electrolytes leads to the formation of a stable LiF solid-electrolyte interphase, which can effectively suppress Li dendrites and the chemical degradation of AN in contact with Li. Accordingly the electrolyte membranes exhibit a wide electrochemical stability window above 4.7 V versus Li+/Li and fire-retardant properties due to the presence of the phosphorus-containing polymer. Atomistic molecular modeling simulations have been performed to determine the structure of the electrolytes on the microscopic scale and to rationalize the trends in ionic conductivity and the transport regime as a function of the electrolyte composition. Finally, our electrolyte membranes enable stable cycling performance for LiFePO4|PMAPC1 + LiTFSI + AN|Li batteries.

International audience; The applicability of organic materials in conventional Li-ion batteries is challenging owing to the lack of lithium-containing and air-stable cathodes. A class of conjugated sulfonamides to be used as lithium-ion positive electrodes is now shown to exhibit reversible charge storage. The applicability of organic battery materials in conventional rocking-chair lithium (Li)-ion cells remains deeply challenged by the lack of Li-containing and air-stable organic positive electrode chemistries. Decades of experimental and theoretical research in the field has resulted in only a few recent examples of Li-reservoir materials, all of which rely on the archetypal conjugated carbonyl redox chemistry. Here we extend the chemical space of organic Li-ion positive electrode materials with a class of conjugated sulfonamides (CSAs) and show that the electron delocalization on the sulfonyl groups endows the resulting CSAs with intrinsic oxidation and hydrolysis resistance when handled in ambient air, and yet display reversible electrochemistry for charge storage. The formal redox potential of the uncovered CSA chemistries spans a wide range between 2.85 V and 3.45 V (versus Li+/Li-0), finely tunable through electrostatic or inductive molecular design. This class of organic Li-ion positive electrode materials challenges the realm of the inorganic battery cathode, as this first generation of CSA chemistries already displays gravimetric energy storage metrics comparable to those of the stereotypical LiFePO4.

Lithium-sulfur batteries (LSBs) have been regarded as a next generation energy storage systems candidate due to its high theoretical energy density. However, the polysulfide dissolution and the sluggish redox reaction kinetics still hinder its practical applications. Herein, a 2D layered graphene micro-sheets, loaded with mesoporous MnOOH (GMs-MnOOH) as an energetic sulfur host for LSBs is reported. This sulfur host material works in two ways: anchoring sulfur and lithium polysulfides by nonpolar GMs and Lewis acidic Mn (III) center of porous structure MnOOH. As a result, with a sulfur content of 56 wt%, GMs-MnOOH/S cathodes present significantly improved rate performance and cycling stability. The GMs-MnOOH/S electrode delivered a specific capacity of 952 mAhg−1 and 807 mAhg−1 at 1C and 2C, respectively. This work provides a promising guidance to realize highly efficient hosts for Li-S batteries with high sulfur loading.

Mg-ion diffusion in cathodes and dissociation in electrolyte complexes are sluggish processes that hinder the development of Mg batteries. Now, a new design of both the cathode and the electrolyte drastically improves the kinetics of these processes, leading to a high-power Mg battery.

Background: The aim was to compare two echocardiographic methods for prosthetic valve effective orifice area (EOA) measurement following transcatheter self-expanding aortic valve implantation. Methods: EOA was calculated according to the continuity equation. Two methods were constructed. In Method #1, the left ventricular outflow tract diameter (LVOTd 1 ) was measured at the entry of the prosthesis (from trailing to leading edge); in Method #2, the LVOTd 2 was measured proximal to the prosthetic valve leaflets (from trailing to leading edge). VTI LVOT was recorded by pulse doppler (PW) from apical windows. The region of the PW sampling should match that of the LVOTd measurement with precise localization. Results: A total of 113 consecutive patients were included in the study. All patients were followed up at one year. The mean transvalvular pressure gradient correlated better with the indexed EOA 1 (EOAI 1 ) (r=-0.701, p

We report the electrochemistry of a hitherto unexplored Na2MoS4 phase as conversion electrode material for Na‐ and Li‐cation reversible storage. The material adopts an amorphous coordination polymer structure, with mixed Mo and S valences. Ex‐situ XPS and in‐situ XRD analysis reveal a complex interplay between Mo and S redox, while excluding the formation of free sulfur, lithium sulfide or other crystalline phases. Na2MoS4 behaves as a mixed ionic‐electronic conductor, with electronic conductivity of 6.1 × 10 ‐4 S cm ‐1 , that allowed the use of this material without any conductive carbon in an electrochemical cell. A reversible capacity of 500 mAh g ‐1 is attained corresponding to 5‐electron redox exchange, with the end‐member reaching from Na5MoS4 . This study not only emphasizes on the excellent charge storage performances of Na2MoS4 for Li or Na batteries, but also enriches the emerging library and knowledge of sulfide phases with mixed anionic and cationic redox.

Hybrid electric vehicles equipped with continuously variable transmission show dramatic improvements in fuel economy and driving performance because they can continuously adjust the operating points of the power source. This article proposes an optimal control strategy for continuously variable transmission–based hybrid electric vehicles with a pre-transmission parallel configuration. To explore the fuel-saving potential of the given configuration, a ‘control-oriented’ quasi-static vehicle model is built, and dynamic programming is adopted to determine the optimal torque split factor and continuously variable transmission speed ratio. However, a single-criterion cost function will lead to undesirable drivability problems. To tackle this problem, the main factors affecting the driving performance of a continuously variable transmission–based hybrid electric vehicle are studied. On that basis, a multicriterion cost function is proposed by introducing drivability constraints. By varying the weighting factors, the trade-off between fuel economy and drivability can be evaluated under a predetermined driving cycle. To validate the effectiveness of the proposed method, simulation experiments are performed under four different driving cycles, and the results indicate that the proposed method greatly enhanced the drivability without significantly increasing fuel consumption. Compared to a single-criterion cost function, the use of multiple criteria is more representative of real-world driving behaviour and thus provides better reference solutions to evaluate suboptimal online controllers.

The hierarchical porous ZnMn 2 O 4 microsphere is successfully synthesized by a facile ultrasonic spray pyrolysis technology combined with the thermal annealing treatment in air. The porous microspheres are built from interconnected porous nanosheets which are composed of numerous nanoparticles with size of approximately 15 nm. This unique structure could not only facilitate the transfer of ions and electrons, but also accommodate large volume expansion and contraction so that it shows excellent electrochemical performance. When used as anode materials for lithium ion batteries (LIBs), the ZnMn 2 O 4 porous microspheres exhibited a discharge capacity of 1044 mA h g −1 after 300 cycles at a current of 500 mA g −1 and superior rate capability (859 mA h g −1 at 2000 mA g −1 ). The highly porous structure with nanosheet networks composed of nanoparticles is responsible for the enhanced performance.

Robust porous SiO2/Si/graphene/C microspheres have been successfully synthesized by a simple two-step process of ultrasonic spraying and partial magnesiothermic reduction. The 3-D porous microspheres consist of Si/SiO2 nanoparticles (around 5–10 nm) covered by a layer of carbon and connected by graphene. We explored the electrochemical properties of the porous microspheres as an anode for lithium ion batteries (LIBs). In SiO2/Si/graphene/C microspheres, numerous pores could leave enough room for volume expansion and contraction of silicon during lithiation and delithiation, and provide large space voids for electrolyte reserves. Meanwhile, graphene plays a role in reinforcing the porous structure. The prepared sample shows superior cyclability with a discharge capacity of 1104.9 mA h g−1 in the second cycle and 1141.6 mA h g−1 over 200 cycles at a current density of 0.1 mA cm−2. The capacity retention is more than 100%, making it very promising as a future LIBs anode.

Microcrystalline graphite, a kind of cheap and infrequently used graphite material, used for the rapid synthesis of graphene nanosheets (MGS) by thermal reduction–exfoliation of graphite oxide at low temperature (as low as 100 °C) is reported. The results indicate that the microcrystalline graphite could be oxidized completely. X-ray diffraction patterns show that the obtained MGS exhibit an amorphous structure. Scanning electron microscopy images show that the MGS samples possess nanoporous structure. The results of N2 adsorption–desorption analysis indicate that the MGS samples possess high Brunauer Emmett Teller surface areas (the highest is 374 m2 g−1). The results of electrochemical tests show that the MGS exfoliated at 400 °C (MGS-400) has better supercapacitive performance than that of MGS exfoliated at 100 °C. The specific capacitance value of MGS-400 is about 212 F g−1 at 5 mV s−1. And also the MGS samples have good rate performance and cycle stability.

Grass-like CuCo2O4 nanowire arrays supported on nickel foam have been successfully synthesized via a hydrothermal method. Electrochemical investigations demonstrate that the material is an excellent electrode for supercapacitors with remarkable performance including a high area capacitance of 611 F g−1 at a current density of 1.7 A g−1, and a desirable cycling stability of 94.8% capacitance retention after 8000 cycles.

A novel three-dimensional graphene/polyaniline (3DGP) composite was achieved by a hydrothermal method from in situ polymerization of a polyaniline/graphene oxide composite and GO suspension. This 3DGP composite possesses a 3D porous network structure and large specific capacity of 648 F g−1 at a current density of 0.5 A g−1. In particular, the capability can reach 356 F g−1 even at 20.0 A g−1, 537 F g−1 at 1.0 A g−1 can also be achieved after 1000 cycles. Therefore, the 3DGP composite is a suitable and promising electrode material for supercapacitors.

In this study, graphene nanosheets (GS) were prepared from a kind of economic and resourceful graphite material, natural microcrystalline graphite, by thermal exfoliation method. The scanning electron microscopy and transmission electron microscopy images show that the obtained GS have porous structure and are well separated and composed of approximately 6–8 wrinkled individual monoatomic graphene layers. The results of nitrogen adsorption–desorption analysis show the GS possess high specific surface area. The results of electrochemistry measurements show that the prepared GS have good supercapacitive performance, the capacitance increase with the oxidation degree of microcrystalline graphite oxide. The highest capacitive performance can reach 175 F g−1 at 0.5 A g−1, and also the GS have good rate performance and cycle stability.

Graphene nanosheets (GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. The results show that the GSs with pore sizes center around 4.0 nm. With an increase of thermal reduction temperature, the number of stacking layers and the structure disorder degree increase, while the oxygen-containing groups content, BET surface area, and electrical resistivity of GSs decrease. The results indicate that 673 K is the preferable thermal exfoliation temperature to acquire good supercapacitive performance. In this case, the GSs have the best supercapacitive performance (233.1 F g−1) in a 6 mol L−1 KOH electrolyte. The prepared GSs at the preferable thermal exfoliation temperature have good rate performance and cycle stability.