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Carbon paper‐supported graphene aerogels are examined as anode electrodes for lithium‐ion batteries, employing a hydrothermal process and a freeze‐drying step. Triethylenetetramine (TETA) and o‐phenylenediamine (OPD) prove to promote graphene aerogel formation and its chemical bonding onto the surface of carbon paper. The electrochemical results demonstrate that the electrode treated with the former diamine has a remarkable rate capability with higher capacities as compared with the electrode treated with the latter diamine and better stability. [ABSTRACT FROM AUTHOR]

In this paper, a series of iron oxide/reduced graphene oxide/carbon nanotube composites (K3‐Fe2O3‐rGO/CNT) with well‐dispersedFe2O3 particles are prepared by in situ reaction and then heat‐treatment, and its electrochemical and battery performancesare studied as the anode material of lithium‐ion batteries. The results show that the introduction of reduced graphene oxide/carbon nanotube (rGO/CNT) improves the electrochemical and battery performances of the prepared electrode material. In particular, the K3‐Fe2O3‐rGO/CNT (30 %) composite material has a reversible capacity of 1559 mAh g−1 after 100 charge/discharge cycles at 100 mA g−1. And its specific discharge capacityis 641.1, 639.7, 609.5, 578.6 and 543 mAh g−1at the current density of 100, 200, 500, 1000 and 2000 mA g−1, respectively,with 84.7 % of capacity retention even with a 10 times increase in current density. The research of charge storage indicates that the electrochemical process is a mixed control process of diffusion and capacitance. The improved electrochemical and battery performancesfor the composite electrode material can be attributed to the enhanced dispersion of the Fe2O3 and the enhanced conductive network provided by rGO/CNT composite carbon. It makes a promising way to prepare high performance of anode material for lithium‐ion battery. [ABSTRACT FROM AUTHOR]

A potential anode material for lithium‐ion batteries (LIBs), Co3O4 has been widely considered by many scholars because of its excellent properties in terms of electrochemical characteristics and theoretical specific capacity. However, according to the existing research results, we found that the improvement of the electrochemical performance of Co3O4 has encountered a bottleneck because its intrinsic conductivity is not high enough, and more importantly, the volume expansion is too significant during the charge and discharge process, which leads to the material structure breaking. Therefore, this paper proposes a simple and scalable solvothermal and subsequent calcination method to prepare Co3O4 and reduced graphene oxide (RGO) composite nanoparticles with superior microstructures, and their morphological and electrochemical properties were investigated at different calcination temperatures. As a high‐performance anode material for lithium‐ion batteries, the Co3O4/RGO nanoparticles obtained at 550 °C exhibited terrific initial discharge capacity of 1714.2 mAh g−1, the reversible specific capacity of 1191.9 mAh g−1 with quality coulombic efficiency 98.17 % at 0.5 A g−1 after 100 cycles and extraordinary rate performance (907.6 mAh g−1 with a coulombic efficiency of 99.2 % at 2 A g−1). The facile synthesis method and excellent findings have led to better application prospects for Co3O4/RGO nanoparticles. [ABSTRACT FROM AUTHOR]

This paper shows that the number of cycles and the crystal structure play an important role in the capacity and cycling ability of lithium‐ion batteries. However, the detailed dynamics and continuity of the capacity decay mechanism caused by the number of cycles and crystal structure need to be further understood at the nanoscale. Molecular dynamics simulation was used to examine the microstructure development and deformation behavior of the Si anode in an electric field. The results show that the increase of the number of cycles leads to a large expansion of the volume of the Si electrode, which further leads to the loss of capacity and the decrease of cycle capacity, as well as the decrease of structural stability. The formation of Si crystal structure from diamond structure to amorphous depends on the depth of lithiation and desulfurization. Due to the presence of a large number of nanoscale voids, the Si anode has undergone volume expansion. The transformation associated with nanogap nucleation caused by the involuntary diffusion process is driven by more cycles, resulting in irreversible capacity loss of lithium‐ion batteries. The analysis model shows that the stress caused by diffusion is not only related to the position of the Si anode, but also to the cycle time. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride‐hexafluoropropylene (PVDF‐HFP) is a standard electrolyte membrane and binder material for lithium‐ion batteries (LIBs) because of the benefits of membrane formation and strong mechanical properties. Still, its use is limited due to unavoidable defects such as high crystallinity and poor electrochemical performance. In this paper, a larger specific surface area and three‐dimensional (3D) permeable lamellae carboxylated g‐C3N4 (HCN) were successfully prepared by HNO3 and introduced into the PVDF‐HFP to obtain a high‐performance composite separator. The wettability and electrolyte absorption of PVDF‐HFP separator can be improved through the carboxylated HCN. More crucially, because PVDF‐HFP has several active sites and low crystallinity, adding HCN can greatly increase the ionic conductivity of separators. The ionic conductivity of PH‐HCN at 25 °C is 0.52 S cm−1, 4.7 times higher than the initial PVDF‐HFP membrane, and the oxidation potential can reach 4.8 V. The assembled lithium‐ion batteries half‐cell has a capacity of 71 % at a 5 C rate and 94 % after 400 cycles at a 2 C rate. Therefore, the improved separator has the potential to be applied to high‐performance LIBs. [ABSTRACT FROM AUTHOR]

The cycling and rate capabilities of LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode material under high cut‐off voltage (≥4.5 V) and high current density have attracted much attention. However, the material's insufficient intrinsic electronic/ion conductivity and interface instability are still key issues restricting its electrochemical performance.In this paper, a graphene/Ta2O5 co‐coating layer is successfully fabricated on the surface of NCM523 to form a cathode material of GTa‐NCM523 to enhance both the electron and lithium‐ion transport during cathode operation. The GTa‐NCM523 cathode material achieves a discharge specific capacity of 147.4 mAh g−1 after 600 cycles at a voltage of 3.0–4.5 V and a rate of 1 C (180 mA g−1) with a capacity retention rate of 81.4 %. In contrast, the uncoated NCM523 only retains 63.2 % of its capability. At an elevated rate of 10 C (1800 mA g−1), the GTa‐NCM523 can achieve a discharge‐specific capacity of up to 113.5 mAh g−1, which is 43.7 % higher than the uncoated NCM523. The co‐coating layer can inhibit HF erosion and accelerate the movement of lithium‐ions and electrons, which account for the superior electrochemical characteristics of the co‐coating layer comprised of graphene and Ta2O5. [ABSTRACT FROM AUTHOR]

To address the issue of excess carbon emissions, China has outlined peaking the carbon emissions and achieving neutrality of carbon goals. New energy storage devices thus have been popularly developed in the past decade. Lithium‐ion batteries(LIBs) have emerged as the most prevalent devices in our daily routines. In the coming decades a huge amount of LIBs will be retired. Spent LIBs are endowed with valuable metal elements that are potentially recyclable. This paper is intended to review the recent studies on the recovery of lithium(Li) and cobalt(Co) from spent LiCoO2 batteries. This paper pays much attention to the hydrometallurgical, pyrometallurgical approaches to recycle lithium and cobalt from spent LIBs including leaching, reducing, and extracting by various inorganic or organic agents in hydrometallurgical methods and different kinds of reductants in pyrometallurgical methods. Last but not least, electrochemical methods, mechanochemistry and biometallurgy are focused for reviewing emerging, low‐cost, environmentally friendly methods. Hopefully, this review can inspire to further studies on recycling lithium and cobalt from spent LiCoO2 LIBs. [ABSTRACT FROM AUTHOR]

The recovery of critical metals from spent lithium‐ion batteries (LIBs) is important to sustainable development and environment protection. In this paper, sec‐octylphenoxyacetic acid (CA‐12) was first used to recover valuable metals in LIBs. The effects of phase modifier, initial feed pH, extraction kinetics and thermodynamics, CA‐12 concentration and saponification degree were studied and optimized. Under the optimal conditions, 99 % of nickel, cobalt and manganese were co‐extracted to the organic phase, and the loss of lithium was 7 %. The extracted metal ions could be stripped with 0.04 mol/L HCl equivalently. In the spent LIBs powder leaching experiment, leaching efficiencies of all components were greater than 95 %. In the impurity removal stage, extractant N902 was used to remove copper, while iron and aluminum were eliminated by hydrolysis. After two‐stage extraction, the total extraction efficiencies of nickel, cobalt and manganese reached 99.7 %, 99.4 %, 98.45 %, respectively. Finally, lithium in the raffinate was precipitated by saturated Na2CO3, the purity of recovered Li2CO3 was up to 97.7 %. After 5 times cycles, CA‐12 still maintained excellent extraction capacity, showing its potential application prospects for recovering critical metals form spent LIBs. [ABSTRACT FROM AUTHOR]

Lithium sulfur batteries hold great promise as the new generation post‐lithium‐ion batteries in virtue of high theoretical energy density (2600 W h/kg) and low cost of sulfur. However, the practical application of the batteries is being hindered by their poor cycling stability and low Coulombic efficiency, which is mainly attributed by the dissolution of polysulfides and low electronic conductivity of sulfur. Herein, a novel cathode host was designed by mixing the nanoflower‐like MnO2 with KB powder loaded on the commercial carbon paper, delivering excellent electrochemical performance even at a high sulfur mass loading of 2.1 mg/cm2. The nanoflower‐like MnO2 obtained from the typical hydrothermal method provides abundant active sites for adsorbing polysulfides chemically. The combination between this chemical capture effect and physical constraint introduced by the pores of nanoflower‐like MnO2 and KB powder suppresses the dissolution of lithium polysulfides out of cathode region. Consequently, the modified MnO2‐KB@carbon paper‐Li2S6 cathode exhibits an initial discharge capacity of 776.4 mAh/g at 0.5 C and retain 814.3 mAh/g after 100 cycles with nearly 100% Coulombic efficiency. Remarkably, self‐discharge rate has been restrained to a very level of 4.7% after 48 h resting, indicating the potential of the nanoflower‐like MnO2‐KB@carbon paper‐Li2S6 cathode for improved preserving ability of lithium sulfur battery. [ABSTRACT FROM AUTHOR]

As the research on lithium‐ion battery cathode materials gradually breaks through the saturation, the anode materials for lithium‐ion batteries have received wide attention because of their promising future. Silicon electrodes, in particular, are attracting increasing attention. In this paper, the Si/G precursor was achieved by simple mechanical ball milling. Two silicon based composite electrode materials Si@TA and Si@TA‐G were synthesized by spontaneous polymerization of tannic acid on precursor surface in Tris buffer solution. For the poor electrical conductivity of silicon, graphite was added as a carbon source to avoid the direct contact between silicon and electrolyte during charge/discharge process by forming tannic acid coating on silicon surface.The Si@TA composites achieve a discharge specific capacity of 927.4 mAh g−1 at 100 mA g−1 current density after 50 cycles with a retention rate of 87.1 % while the reversible capacity of Si@TA‐G is 1249.8 mAh g−1 with a retention rate is 93.6 %. This unique composite method provides new insights into the modification of silicon anode materials. [ABSTRACT FROM AUTHOR]

In this paper, a two‐dimensional macroscopic element model was established for dual‐electrolyte Li‐air batteries (LABs) by COMSOL Multiphysics. The model combined Structural Mechanics module, Lithium‐Ion Battery (liion), Transport of Diluted Species in Porous Media (tds) and Ordinary Differential Equations (ODEs) and Differential Algebraic Equations (DAEs) at the transient condition. It is illustrated that the porosity of the battery is the maximum, the transmission performance of O2 and Li+ is the best, the discharge specific capacity is 2044 mAh ⋅ g−1. The over‐potential is the minimum when 0.5 MPa preload force is applied to the dual‐electrolyte LABs in the range of 0–2 MPa according to the numerical simulation. Moreover, the effect of the best preload force of 0.5 MPa during the process of the experiment is substantiated. [ABSTRACT FROM AUTHOR]

Traditional polyolefin separators suffer from poor heat resistance and wettability with electrolyte, which leads to compromised safety and electrical properties of lithium‐ion batteries. Polyvinylidene fluoride (PVDF) has high thermal stability and good chemical stability, but its high crystallinity leads to low ionic conductivity. In order to solve these problems, polyvinyl alcohol (PVA) resin was introduced in this paper, and the PVDF/PVA composite separator was prepared by double‐needle electrospinning. The introduction of PVA resin improved its mechanical properties and electrolyte wettability, and ionic conductivity after assembly into a battery. Double‐needle electrospinning process is simple and can preserve the surface properties of fibers, and the prepared composite separator had a high porosity and electrolyte uptake. The composite separator has an ionic conductivity of 2.454 mS ⋅ cm−1, a high capacity retention rate of 97.5 % after 100 charge and discharge cycles, and a capacity retention rate of 86.8 % under 2 C high‐rate discharge. The results show that the battery assembled with PVDF/PVA composite separator has high safety performance and electrical performance, and has application prospects. [ABSTRACT FROM AUTHOR]

Lignin, as the second most abundant natural polymer, has not been fully utilized in the industrial field due to the complex structure and functional groups. In this paper, polyvinyl chloride (PVC) coated lignin‐silica composites (PLS) with excellent cycling performance are prepared from rice husk and PVC through the method of alkali extraction and acid precipitation and mechanical mixing process. Due to the existence of functional groups on the surface of lignin, it can be closely combined with PVC to form a stable structure. The first discharge specific capacity and Coulombic efficiency of PLS is 1436 mA h g−1 and 56 %, respectively, and the reversible capacity is 720 mA h g−1 after 200 cycles at 0.1 A g−1, showing a stable cycling performance. This work promotes the application of lignin in the SiO2/C anode material of lithium ion battery, and confirms the stable combination between PVC and organic carbon. [ABSTRACT FROM AUTHOR]

Silicon (Si)‐based materials have become one of the most promising anode materials for lithium‐ion batteries due to their high energy density, but in practice, lithium ions embedded in Si anode materials can lead to a maximum volume expansion of nearly three times, which can cause material chalking and shedding, thus affecting the battery cycle life, while the poor electrical conductivity of Si as a semiconductor material also restricts its further development. A lot of research has been carried out based on these problems. This paper reviews the recent research in three aspects: binder, Si surface structure function, and Si carbon composites, summarizes the research lines, methods, and problems of different Si‐based materials, and gives an outlook on their future research. [ABSTRACT FROM AUTHOR]

This article provides a low cost and green environmental preparation method to produce a high performance of stannum‐carbon lithium battery anode material. The advantage of this method is not only for improving the performance and stability comparing with the stannum‐carbon lithium battery, but also show a way for the industrial scale for the applications at the same time. This paper provides a reasonably designed hybrid composite as lithium ion battery anode that shows a reversible capacity of 440 mAh g−1 after 500 cycles at 1.0 A g−1. This result is mainly attributed to the nanocrystallization of stannum and the introduction of expansion space by combination of wheat flour nature properties and redox process. [ABSTRACT FROM AUTHOR]

Transition‐Metal chalcogenides have high Li‐ion storage capacity and considerable cycle performance, which has attracted great interest from researchers and is expected to replace graphite materials in the field of Li ion batteries. The purpose of this paper is to find a low‐cost and ecofriendly method for producing copper‐based chalcogenides as anodes with a high capacity and long cycling stability for lithium ion batteries. In our strategy, carbon nanospheres are used as templates to prepare precursor Cu(OH)2@C. Then, the Cu(OH)2@C is converted into copper‐based chalcogenides by different routes. The structure and morphology of the as‐synthesized materials is characterized by the X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. The anode electrochemical performance of the samples was investigated by galvanostatic cycling (GC) vs. Li/Li+ at different current rate. Compared to other copper chalcogenides, the synthesized copper oxide shows better charge/discharge cycle stability and rate performance. Its capacity retention is as high as 128 % at a current density of 0.5 C after 200 cycles. [ABSTRACT FROM AUTHOR]

Abstract: Three‐dimensional microtubular SnO2/V2O5 composites with various SnO2 contents (2.2, 12.1 and 25.2 wt%) were fabricated by a facile sol−gel method employing natural cellulose substance (e. g., filter paper) as template. Thin VxOy/SnO2 gel layer was first deposited onto the surfaces of the cellulose microfibers of the filter paper through a dipping process, and then the as‐prepared VxOy/SnO2/cellulose composites were calcined in air to give the SnO2/V2O5 composites. The obtained composites inherit the morphology of the initial cellulose substance on the micrometer scale and consist of intricate microtubes composed of V2O5 nanorods with SnO2 nanoparticles anchored on the surfaces. Due to the unique three‐dimensional network structure of the composites and the synergetic effect of the V2O5 and SnO2 species, the SnO2/V2O5 composites displayed enhanced electrochemical performances when employed as cathode materials for lithium‐ion batteries. The composite with a SnO2 loading content of 12.1 wt% retained a stable discharge capacity of 126 mAh g−1 after 150 discharge/charge cycles at a current density of 0.1 A g−1. The three‐dimensional microtubular structure inherited from the cellulose substance improves the structural stability of the electrode materials and facilitates the diffusion of lithium ions, and the existence of SnO2 with an appropriate loading content enhances the conductivity of the composites. [ABSTRACT FROM AUTHOR]

In order to satisfy the growing energy demand of large‐scale applications such as energy storage for renewable sources and for electromobility, advanced electroactive materials are required for energy storage technologies. The aim of this work is to develop a new cathode concept for Li‐ion batteries, which allows high charging/discharging rates as well as high gravimetric capacities. The composite cathode consisting of LiFePO4 (high rates) and S (high capacity), takes advantage of the benefits of both materials. However, it is a challenge considering the reactivity of both materials, and the electrolytes needed for each of them. This paper deals with some strategies to make the composite work; the problems encountered when having two materials with different electrochemical behavior in the same electrode in a battery have been partially solved. The voltammetric studies of this work show promising results for the development of the new concept of lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

As conversion material, ZnMn2O4 has a high theoretical specific capacity as an anode for Lithium‐ion batteries. This paper has designed a facile method to prepare urchin‐like ZnMn2O4 architectures with high quality and well crystallinity. The resultant urchin‐like ZnMn2O4 architectures exhibit high discharge capacity and excellent cycling stability. The initial discharge capacity of urchin‐like ZnMn2O4 architectures is 1167 mAh g−1 at 0.4 A g−1 and the electrode materials could maintain high reversible capacity of 889 mAh g−1 after 150 cycles. Even in the high current density of 1 A g−1, the electrode of urchin‐like ZnMn2O4 can keep a high reversible capacity of 578 mAh g−1 after 300 cycles. The improved electrochemical performance can be ascribed to the urchin‐like architectures of the as‐prepared ZnMn2O4, which could be conducive to the transmission of lithium ions and electrons and provide sufficient void spaces to tolerate the volume change during the Li+ intercalation. These results revealed that as‐prepared urchin‐like ZnMn2O4 architectures would be a promising anode for high performance Lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Recent works show the promise for lithium tetrafluoroborate (LiBF4) as an electrolyte salt for lithium‐ion batteries. In this paper, LiBF4 is synthesized by a novel reaction between the as‐prepared anhydrous Li2SO3 and (C2H5)2O⋅BF3 in an aprotic solvent. The moisture sensitivity and water‐removing method of LiBF4 materials which has been dried under vacuum for 2 h at different temperature, is studied by Fourier transform infrared spectroscopy measurements. Results show that almost all of the adsorbed water would be removed at above 65 °C. With the increase of drying temperature, crystal water will decrease slowly, and almost disappear completely at 170 °C. However, due to the thermal decomposition of LiBF4, LiF and BF2OH impurities are formed as the temperature reaches 165 °C. So, we determine that the proper drying temperature is 155 °C, though the trace water cannot be removed thoroughly. Besides, influences of trace water on the electrochemical performance of Li/MCMB half‐cell with LiBF4 as electrolyte salt has been investigated. Results show that discharge plateaus at about 1.5 V vs. Li/Li+ will be lengthened with the increase of water content. Subsequently, the so‐called solid‐electrolyte interphase (SEI) film will become thicker and more resistant, which leads to poor Li+ ion migration and bad cycling performance. [ABSTRACT FROM AUTHOR]

SnO2 is known as a promising anode candidate for lithium‐ion batteries (LIBs), but suffers from the low electrical conductivity and severe volume variation during cycling, which restraint its practical applications. To solve these issues, we successfully fabricated the three‐dimensional structure of carbon obtained from corn stalks and SnO2 composites. The materials exhibit excellent electrochemical performance. After 100 cycles, it shows a reversible capacity of 691 mA h g−1 at a current density of 0.2 C. Excellent cycle performance is due to the unique structure, which has a strong internal chemical bond between the SnO2 nanoparticles (SnO2 NPs) and the carbon skeleton, preventing SnO2 NPs from falling off the 3D network during the cycle. This work may provide a broader vision into synthesising C‐SnO2 composites for high‐performance anode materials of LIBs. In this paper, we successfully fabricated the three‐dimensional structure of carbon obtained from corn stalks and SnO2 composites by a simple one‐step hydrothermal method. The materials exhibit excellent electrochemical performance. After 100 cycles, it shows a reversible capacity of 691 mA h g−1 at a current density of 0.2 C. Its electrochemical performance is much higher than the SnO2 used in the market. [ABSTRACT FROM AUTHOR]

A hierarchically nanotubular MoO3/SnO2 composite was synthesized based on the layer‐by‐layer self−assemble process followed by a calcination treatment, employing natural cellulose substance (commercial filter paper) as structural scaffold. This nanocomposite is composed of molybdenum trioxide nanocrystallites immobilized as a thin layer on the tin oxide nanotube surface. As being utilized as a host material for lithium storage, the MoO3/SnO2 nanocomposite exhibited high reversible specific capacity, good cyclability and enhanced rate performance as compared with the pure SnO2 and MoO3 counter materials. For the nanotubular MoO3/SnO2 composite with 48.9 wt% MoO3 content, it delivered an initial discharge capacity of 1930.6 mAh g−1 and a stable specific capacity of 1084.1 mAh g−1 after 100 discharge/charge cycles at a current density of 100 mA g−1. The excellent lithium storage performance of the MoO3/SnO2 composite is benefited from the sophisticated hierarchically three‐dimensional network structures and the synergistic interaction between MoO3 and SnO2 components upon repeated lithiation/delithiation processes. A cellulose templated nanotubular MoO3/SnO2 composite was synthesized based on a self‐assemble approach, which showed excellent lithium storage properties as being used as an anodic material for lithium‐ion batteries (see figure). [ABSTRACT FROM AUTHOR]