Search

Cobalt substitution for manganese sites in Na0.44MnO2 initiates a dynamic structural evolution process, yielding a composite cathode material comprising intergrown P2 and P3 phases. The novel P2/P3 composite cathode exhibits a reversible phase transition process during Na+ extraction/insertion, showcasing its attractive battery performance in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (NIBs) have emerged as a promising alternative to commercial lithium‐ion batteries (LIBs) due to the similar properties of the Li and Na elements as well as the abundance and accessibility of Na resources. Most of the current research has been focused on the half‐cell system (using Na metal as the counter electrode) to evaluate the performance of the cathode/anode/electrolyte. The relationship between the performance achieved in half cells and that obtained in full cells, however, has been neglected in much of this research. Additionally, the trade‐off in the relationship between electrochemical performance and cost needs to be given more consideration. Therefore, systematic and comprehensive insights into the research status and key issues for the full‐cell system need to be gained to advance its commercialization. Consequently, this review evaluates the recent progress based on various cathodes and highlights the most significant challenges for full cells. Several strategies have also been proposed to enhance the electrochemical performance of NIBs, including designing electrode materials, optimizing electrolytes, sodium compensation, and so forth. Finally, perspectives and outlooks are provided to guide future research on sodium‐ion full cells. [ABSTRACT FROM AUTHOR]

Alloying‐type antimony (Sb) with high theoretical capacity is a promising anode candidate for both lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs). Given the larger radius of Na+ (1.02 Å) than Li+ (0.76 Å), it was generally believed that the Sb anode would experience even worse capacity degradation in SIBs due to more substantial volumetric variations during cycling when compared to LIBs. However, the Sb anode in SIBs unexpectedly exhibited both better electrochemical and structural stability than in LIBs, and the mechanistic reasons that underlie this performance discrepancy remain undiscovered. Here, using substantial in situ transmission electron microscopy, X‐ray diffraction, and Raman techniques complemented by theoretical simulations, we explicitly reveal that compared to the lithiation/delithiation process, sodiation/desodiation process of Sb anode displays a previously unexplored two‐stage alloying/dealloying mechanism with polycrystalline and amorphous phases as the intermediates featuring improved resilience to mechanical damage, contributing to superior cycling stability in SIBs. Additionally, the better mechanical properties and weaker atomic interaction of Na−Sb alloys than Li−Sb alloys favor enabling mitigated mechanical stress, accounting for enhanced structural stability as unveiled by theoretical simulations. Our finding delineates the mechanistic origins of enhanced cycling stability of Sb anode in SIBs with potential implications for other large‐volume‐change electrode materials. [ABSTRACT FROM AUTHOR]

High‐voltage lithium‐ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte‐electrode interphase at high voltage. Herein, a robust additive‐induced sulfur‐rich interphase is constructed by introducing an additive with ultrahigh S‐content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi0.5Co0.2Mn0.3O2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li+ sheath, but the strong interactions between MMDS and PF6− anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur‐rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur‐rich additive‐induced electrolyte‐electrode interphase for stable high‐voltage LIBs. [ABSTRACT FROM AUTHOR]

As a class of promising cathodes in the field of large-scale power storage systems especially for alkali-metal-ion batteries (MIBs), Prussian blue (PB) and its analogues (PBAs) have received wide research attention due to their open framework, high theoretical specific capacity, and simple synthesis method. For large-scale applications, cathode materials with low-cost and long cycle life are preferred. However, only a few of the review papers have concentrated on the detailed analysis of low-cost PBAs, including Fe-based and Mn-based PBAs, which also show excellent electrochemical performance. This review aims to first provide an all-sided understanding of low-cost PBAs in terms of their application and recent progress in MIBs. Then, the major challenges such as inferior electrochemical properties of low-cost PBAs are discussed. Meanwhile, we provide feasible strategies to prepare PBA electrodes with advanced electrochemical performance. Finally, we present some personal perspectives and guidance for future research, aiming to narrow the gap between laboratory investigation and practical application. [ABSTRACT FROM AUTHOR]

Prussian blue analogues (PBAs) have been regarded as promising cathode materials for alkali‐ion batteries owing to their high theoretical energy density and low cost. However, the high water and vacancy content of PBAs lower their energy density and bring safety issues, impeding their large‐scale application. Herein, a facile "potassium‐ions assisted" strategy is proposed to synthesize highly crystallized PBAs. By manipulating the dominant crystal plane and suppressing vacancies, the as‐prepared PBAs exhibit increased redox potential resulting in high energy density up to ≈450 Wh kg−1, which is at the same level of the well‐known LiFePO4 cathodes for lithium‐ion batteries. Remarkably, unconventional highly‐reversible phase evolution and redox‐active pairs were identified by multiple in situ techniques for the first time. The preferred guest‐ion storage sites and migration mechanism were systematically analysed through theoretical calculations. We believe these results could inspire the design of safe with high energy density. [ABSTRACT FROM AUTHOR]

Carbon nanospheres (CNSs) have attracted great interest in energy conversion and storage technologies due to their excellent chemical and thermal stability, high electrical conductivity and controllable size structure characteristics. In order to further improve the energy storage properties, many efforts have been made to design suitable nanocarbon spherical materials to improve electrochemical performance. In this overview, we summarize the recent research progress on CNSs, mainly focusing on the synthesis methods and their application as high-performance electrode materials in rechargeable batteries. As for the synthesis methods, hard template methods, soft template methods, the extension of the Stöber method, hydrothermal carbonization, aerosol-assisted synthesis are described in detail. In addition, the use of CNSs as electrodes in energy storage devices (mainly concentrated on lithium-ion batteries (LIBs)), sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are also discussed in detail in this article. Finally, some perspectives on the future research and development of CNSs are provided. [ABSTRACT FROM AUTHOR]

Prussian blue analogs (PBAs) are promising cathode materials for sodium‐ion batteries (SIBs) due to their low‐cost, similar energy density comparable with that of LiFePO4 in lithium‐ion batteries, and long cycle life. Nevertheless, crystal water (≈10 wt%) in PBAs from aqueous synthesis environments can bring significant side effects in real SIBs, especially for calendar life and high temperature storage performance. Therefore, it is of great importance to eliminate crystal water in PBAs for future commercial applications. Herein, a facile heat‐treatment method is reported in order to remove water from Fe‐based PBAs. Although the heat‐treated sample can be easily rehydrated in air, it still exhibits a stable cycling performance over 2000 times under controlled charge cut‐off voltage. In situ synchrotron high‐temperature powder X‐ray diffraction demonstrates that the as‐prepared sample is maintained at a new trigonal phase after dehydration. Moreover, the redox reaction of low‐spin Fe2+/Fe3+ is activated and the high‐temperature storage performance of as‐prepared sample is significantly improved after removal of water. [ABSTRACT FROM AUTHOR]

Hard carbon (HC) is recognized as a promising anode material with outstanding electrochemical performance for alkali metal‐ion batteries including lithium‐ion batteries (LIBs), as well as their analogs sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs). Herein, a comprehensive review of the recent research is presented to interpret the challenges and opportunities for the applications of HC anodes. The ion storage mechanisms, materials design, and electrolyte optimizations for alkali metal‐ion batteries are illustrated in‐depth. HC is particularly promising as an anode material for SIBs. The solid‐electrolyte interphase, initial Coulombic efficiency, safety concerns, and all‐climate performances, which are vital for practical applications, are comprehensively discussed. Furthermore, commercial prototypes of SIBs based on HC anodes are extensively elaborated. The remaining challenges and research perspectives are provided, aiming to shed light on future research and early commercialization of HC‐based SIBs. [ABSTRACT FROM AUTHOR]

Next‐generation sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) are considered to be promising alternatives to replace current lithium‐ion batteries due to the high abundance of sodium and potassium resources. New energetic vanadium‐based compounds that undergoes multielectron reactions and demonstrate good sodium/potassium storage capability, provide new solutions for high‐performance SIBs/PIBs in terms of high energy/power density and long‐time cyclability. So far, desirable rich redox centers (V2+‐V5+), consolidated frameworks, and the high theoretical capacities of vanadium‐based compounds have been widely explored for practical applications. Rational materials design utilizing vanadium multiredox centers and the fundamental understanding of their charge‐transfer processes and mechanisms are critical in the development of high‐performance battery systems. The scientific importance and basic design strategies for high performance V‐based anode/cathode materials, structure‐function properties and state‐of‐the‐art understanding of V‐based electrode materials are herein classified and highlighted alongside their design strategies. The important role of the valence electron layer of vanadium, and the scientific advances of vanadium partitions in other electrochemical behaviors are also summarized in detail. Finally, relevant strategies and perspectives discussed in this review provide practical guidance to explore the undiscovered potentials of multi‐electron reaction relationships of not only V‐based composites, but also other types of electrode materials. [ABSTRACT FROM AUTHOR]

Abstract: Since their successful commercialization in 1990s, lithium‐ion batteries (LIBs) have been widely applied in portable digital products. The energy density and power density of LIBs are inadequate, however, to satisfy the continuous growth in demand. Considering the cost distribution in battery system, it is essential to explore cathode/anode materials with excellent rate capability and long cycle life. Nanometer‐sized electrode materials could quickly take up and store numerous Li+ ions, afforded by short diffusion channels and large surface area. Unfortunately, low thermodynamic stability of nanoparticles results in electrochemical agglomeration and raises the risk of side reactions on electrolyte. Thus, micro/nano and hetero/hierarchical structures, characterized by ordered assembly of different sizes, phases, and/or pores, have been developed, which enable us to effectively improve the utilization, reaction kinetics, and structural stability of electrode materials. This review summarizes the recent efforts on electrode materials with hierarchical structures, and discusses the effects of hierarchical structures on electrochemical performance in detail. Multidimensional self‐assembled structures can achieve integration of the advantages of materials with different sizes. Core/yolk–shell structures provide synergistic effects between the shell and the core/yolk. Porous structures with macro‐, meso‐, and micropores can accommodate volume expansion and facilitate electrolyte infiltration. [ABSTRACT FROM AUTHOR]

Abstract: Sodium‐ion batteries (SIBs) have been considered as the most promising candidate for large‐scale energy storage system owing to the economic efficiency resulting from abundant sodium resources, superior safety, and similar chemical properties to the commercial lithium‐ion battery. Despite the long period of academic research, how to realize sodium‐ion battery commercialization for market applications is still a great challenge. Thus, from the perspective of future practical application, this review will identify the factors that are restricting commercialization, and evaluate the existing active materials and sodium‐ion‐based full‐cell system. The design and development trends that are needed for SIBs to meet the requirements of practical applications in large‐scale energy storage will also be discussed in detail. [ABSTRACT FROM AUTHOR]

The non-aqueous lithium oxygen battery has been considered as one of the most promising energy storage systems owing to its potentially high energy density, exceeding that of any other existing storage system for storing sustainable and clean energy. The success of Li-O2 batteries could efficiently reduce greenhouse gas emissions and the consumption of non-renewable fossil fuels. How to achieve high round-trip efficiency, high capacity, and satisfactory cycling performance, however, is still a great challenge for the lithium oxygen battery. Thus, this report will point out what factors will affect the electrochemical performance and will aim to describe how to increase the electrochemical performance by air electrode optimization. Based on recent achievements, several approaches to solving this problem, such as synthesizing electrocatalysts with high catalytic activity and designing appropriate air electrode structures, are described in details. Also, recent progress associated with novel air electrode designs and understanding the reaction process is discussed. [ABSTRACT FROM AUTHOR]

Room temperature sodium-sulfur (RT-Na/S) batteries have recently regained a great deal of attention due to their high theoretical energy density and low cost, which make them promising candidates for application in large-scale energy storage, especially in stationary energy storage, such as with electrical grids. Research on this system is currently in its infancy, and it is encountering severe challenges in terms of low electroactivity, limited cycle life, and serious self-charging. Moreover, the reaction mechanism of S with Na ions varies with the electrolyte that is applied, and is very complicated and hard to detect due to the multi-step reactions and the formation of various polysulfides. Therefore, understanding the chemistry and optimizing the nanostructure of electrodes for RT-Na/S batteries are critical for their advancement and practical application in the future. In the present review, the electrochemical reactions between Na and S are reviewed, as well as recent progress on the crucial cathode materials. Furthermore, attention also is paid to electrolytes, separators, and cell configuration. Additionally, current challenges and future perspectives for the RT-Na/S batteries are discussed, and potential research directions toward improving RT-Na/S cells are proposed at the end. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) have recently attracted considerable attention and are considered as an alternative to lithium ion batteries (LIBs), owing to the cheap price and abundance of sodium resources. However, the commercialization of SIBs has so far been impeded by the low energy density and unstable cycle life of electrodes, especially as cathodes. Although some cathode candidates with a stable cycle life and high energy density have been developed using nanotechnologies, the commercial feasibility is seldom taken into account. This research news article provides an insight into the commercial prospects of existing cathode materials for SIBs in terms of environmental friendliness, manufacturing cost, synthesis methods and electrochemical performance. [ABSTRACT FROM AUTHOR]

Organic electrode materials bring about new possibilities for the next generation green and sustainable lithium/sodium ion batteries (LIBs/SIBs) owing to their low cost, environmental benignity, renewability, flexibility, redox stability and structural diversity. However, electroactive organic compounds face many challenges in practical applications for LIBs/SIBs, such as high solubility in organic electrolytes, poor electronic conductivity, and low discharge potential as postive materials. Quinone organic materials are the most promising candidates as electrodes in LIBs/SIBs because of their high theoretical capacity, good reaction reversibility and high resource availability. While quinone electrode materials (QEMs) have so far received less attention in comparison with other organic electrode materials in secondary batteries. In this paper, an overview of the recent developments in the field of QEMs for LIBs/SIBs is provided, emphasizing on the modifications of the quinone compounds in solubility, electronic conductivity, and discharge plateaus. Finally, multifaceted modification approaches are analyzed, which can stimulate the practical applications of QEMs for LIBs/SIBs. [ABSTRACT FROM AUTHOR]

An excellent integrated anode (Sn-AB) is constructed by using epoxy (A)-amine (B) glue binding with ultrafine Sn nanoparticles. The electrode with strong adhesion and tensile strength can effectively tolerate the large volume changes of Sn, thereby guaranteeing excellent Li-storage properties. The development of AB binder, therefore, provides a novel and potential tactics for enhancement of electrode integration and mechanical strength. [ABSTRACT FROM AUTHOR]

Hierarchical SnO2 hollow spheres self-assembled from nanosheets were prepared with and without carbon coating. The combination of nanosized architecture, hollow structure, and a conductive carbon layer endows the SnO2-based anode with improved specific capacity and cycling stability, making it more promising for use in lithium ion batteries. [ABSTRACT FROM AUTHOR]

A series of Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0, 0.025, 0.05, 0.075, and 0.1) cathode materials for LIBs were prepared by the sol-gel method. Structural characterization of Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0, 0.025, 0.05, 0.075, and 0.1) samples was conducted by synchrotron X-ray diffraction. The morphology and oxidation states of Fe 2+ and V 3+ in the Li 2 Fe 1-3 x /2 V x P 2 O 7 samples were confirmed by scanning electron microscopy and magnetic susceptibility measurements, respectively. The electrochemical measurements indicated that Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0.025) delivered the higher reversible capacity of 79.9 mAh g −1 at 1 C in the voltage range of 2.0 - 4.5 V with higher 77.9% capacity retention after 300 cycles than those of Li 2 FeP 2 O 7 (48.9 mAh g −1 and 72.6%). Moreover, the rate capability of Li 2 Fe 1-3 x /2 V x P 2 O 7 ( x = 0.025) were also significantly enhanced through vanadium substitution to iron of Li 2 Fe 1-3 x /2 V x P 2 O 7 . The vanadium substituted to Fe2 site of Li 2 FeP 2 O 7 decreases Li occupying the Li5 position in the FeO 5 unit, leading to a low degree exchange between Li and Fe in the MO 5 (M = Li and Fe). The low degree cation disorder was beneficial to lithium-ion extraction/insertion during the charge-discharge process and hence enhances the capacity and rate capability. [ABSTRACT FROM AUTHOR]

Sodium-ion energy storage, including sodium-ion batteries (NIBs) and electrochemical capacitive storage (NICs), is considered as a promising alternative to lithium-ion energy storage. It is an intriguing prospect, especially for large-scale applications, owing to its low cost and abundance. MoS2 sodiation/desodiation with Na ions is based on the conversion reaction, which is not only able to deliver higher capacity than the intercalation reaction, but can also be applied in capacitive storage owing to its typically sloping charge/discharge curves. Here, NIBs and NICs based on a graphene composite (MoS2/G) were constructed. The enlarged d-spacing, a contribution of the graphene matrix, and the unique properties of the MoS2/G substantially optimize Na storage behavior, by accommodating large volume changes and facilitating fast ion diffusion. MoS2/G exhibits a stable capacity of approximately 350 mAh g−1 over 200 cycles at 0.25 C in half cells, and delivers a capacitance of 50 F g−1 over 2000 cycles at 1.5 C in pseudocapacitors with a wide voltage window of 0.1-2.5 V. [ABSTRACT FROM AUTHOR]

Abstract: A high performance Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by the microwave-assisted hydrothermal method followed by a post annealing process. The synchrotron X-ray diffraction analysis results confirmed that single-phase Li3V2(PO4)3 with monoclinic structure was obtained. Scanning electron microscope and transmission electron microscope images revealed that the as-prepared Li3V2(PO4)3 was composed of nanowires and microsized particles. Electrochemical results demonstrated that the Li3V2(PO4)3 electrode measured at 10 C after 500 cycles can deliver discharge capacities of 85.4 mAh g−1 and 103.4 mAh g−1, with a capacity retention of 99.3% and 95.9%, in the voltage ranges of 3.0–4.3 V and 3.0–4.8 V, respectively, indicating good cycling stability. Furthermore, the electrochemical performance of Li3V2(PO4)3 in ionic liquid electrolytes between 3.0 V and 4.8 V was also measured. [Copyright &y& Elsevier]

Abstract: To overcome the problems of vanadium dissolution and the higher charge transfer resistance that results from it, VO2/graphene composite has been synthesized by an in-situ hydrothermal process directly from graphene oxide and V2O5, and characterized by X-ray diffraction, Raman spectroscopy, FT-IR spectroscopy, thermogravimetric analysis, atomic force microscope, and field emission scanning electron microscopy. Electrochemical tests show that the VO2/graphene composite features high discharge capacity (380 mAh g−1) and 99% capacity retention after 50 cycles. It has very low resistance, only 67% of that of pure VO2, indicating the enhancement of electronic conductivity. Carbon dispersed in the electrode material can provide a pathway for electron transport, resulting in improvement of the electronic conductivity. Graphene woven VO2 nanoribbons prevent the agglomeration of VO2 nanoribbons, meanwhile graphene and the VO2 nanoribbons together form a porous network in the random hybrid composite that can be filled with electrolyte, resulting in superior performance and enhanced reversible capacity in comparison with the pure VO2. Thus, this work provides a facile route to synthesize VO2/graphene composite which shows excellent electrochemical performance and is a potential material for lithium ion battery. [Copyright &y& Elsevier]

ABSTRACT: From energy and environmental consideration, an industrial waste product, coal tar pitch (CTP), is used as the carbon source for Si/AC composite. We exploited a facile sintering method to largely scale up Si/amorphous carbon nanocomposite. The composites with 20wt.% silicon with PVdF binder exhibited stable lithium storage ability for prolonged cycling. The composite anode delivered a capacity of 400.3mAhg−1 with a high capacity retention of 71.3% after 1000 cycles. Various methods are used to investigate the reason for the outstanding cyclability. The results indicate that the silicon nanoparticles are wrapped by amorphous SiO x and AC in Si/AC composite. This uniform structure is very favorable to lithium storage, the SiO x and AC layers can supply sufficient conductivity and strong elasticity to suppress the stress resulting from the reaction of Si with Li during charge/discharge process. [Copyright &y& Elsevier]

Abstract: LiNi1/3Mn1/3Co1/3O2 (NMC) as a cathode material for lithium ion batteries has been synthesized by the sol–gel method. The X-ray diffraction Rietveld refinement results indicated that single-phase NMC with hexagonal layered structure was obtained. Scanning electron microscope images revealed well crystallized NMC with uniform particle size in the range of 100–200 nm. The performance of the NMC electrodes with sodium carboxylmethyl cellulose (CMC), poly(vinylidene fluoride) (PVDF), and alginate from brown algae as binders was compared. Constant current charge–discharge test results demonstrated that the NMC electrode using CMC as binder had the highest rate capability, followed by those using alginate and PVDF binders, respectively. Electrochemical impedance spectroscopy test results showed that the electrode using CMC as the binder had lower charge transfer resistance and lower apparent activation energy than the electrodes using alginate and PVDF as the binders. The apparent activation energies of NMC electrodes using CMC, alginate, and PVDF as binders were calculated to be 27.4 kJ mol−1, 33.7 kJ mol−1, and 36 kJ mol−1, respectively. [Copyright &y& Elsevier]

Abstract: A series of Li x CoPO4 (x =0.90, 0.95, 1, 1.05) compounds with different lithium content in the starting compositions were prepared by the sol–gel method. The phase identification was carried out by X-ray diffraction and neutron diffraction. The structure, atom positions, and occupancies were characterized by neutron diffraction. The morphology of Li x CoPO4 (x =0.90, 0.95, 1, 1.05) was examined by field emission scanning electron microscopy. Electrochemical analysis indicated that Li0.95CoPO4 presented the highest discharge capacity at various current densities among all the different x value compounds. The Li0.95CoPO4 showed better cycling stability and coulombic efficiency in the room temperature ionic liquid electrolyte ([C3mpyr][NTf2] containing 1M LiNTf2) at various current densities in the voltage range of 3.5–5.0V than in the conventional electrolyte (1M LiPF6 in ethylene carbonate:diethyl carbonate). [Copyright &y& Elsevier]

Three types of transition metal oxide/carbon composites including FeO/C, NiO/C and CuO/CuO/C synthesized via spray pyrolysis were used as anode for lithium ion battery application in conjunction with two types of ionic liquid: 1 M LiN(SOCF) (LiTFSI) in 1-ethyl-3-methyl-imidazolium bis(fluorosulfonlyl)imide (EMI-FSI) or 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (Py13-FSI). From the electrochemical measurements, the composite electrodes using Py13-FSI as electrolyte show much better electrochemical performance than those using EMI-FSI as electrolyte in terms of reversibility. The FeO/C composite shows the highest specific capacity and the best capacity retention (425 mAh g) under a current density of 50 mA g for up to 50 cycles, as compared with the NiO/C and CuO/CuO/C composites. The present research demonstrates that Py13-FSI could be used as an electrolyte for transition metal oxides in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Nanocrystalline MnO2 was synthesized by the hydrothermal method with or without pulsed magnetic fields. It was found that the morphology of the MnO2 prepared without magnetic field has an urchin-like structure, while the MnO2 prepared with magnetic fields has a rambutan-like structure. A pronounced increase in the Brunauer–Emmett–Teller specific surface area was obtained when the intensities of the pulsed magnetic fields increased. The battery performances were improved for the samples prepared with magnetic fields. The MnO2 prepared under a magnetic field of 4 T shows a capacity of 121.8 mAh g−1, while the MnO2 prepared without magnetic field only shows 103.0 mAh g−1 after 30 cycles. [ABSTRACT FROM AUTHOR]

Abstract: Si/graphene composite was prepared by simply mixing of commercially available nanosize Si and graphene. Electrochemical tests show that the Si/graphene composite maintains a capacity of 1168mAhg−1 and an average coulombic efficiency of 93% up to 30 cycles. EIS indicates that the Si/graphene composite electrode has less than 50% of the charge-transfer resistance compared with nanosize Si electrode, evidencing the enhanced ionic conductivity of Si/graphene composite. The enhanced cycling stability is attributed to the fact that the Si/graphene composite can accommodate large volume charge of Si and maintain good electronic contact. [Copyright &y& Elsevier]

Abstract: NiO–C nanocomposite was prepared by a spray pyrolysis method using a mixture of Ni(NO3)2 and citric acid solution at 600°C. The microstructure and morphology of the NiO–C composite were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) mapping, and thermogravimetric analysis (TGA). The results showed that the NiO nanoparticles were surrounded by amorphous carbon. Electrochemical tests demonstrated that the NiO–C nanocomposites exhibited better capacity retention (382mAhg−1 for 50cycles) than that of pure NiO (141mAhg−1 for 50cycles), which was also prepared by spray pyrolysis using only Ni(NO3)2 as precursor. The enhanced capacity retention can be mainly attributed to the NiO–C composite structure, composed of NiO nanoparticles surrounded by carbon, which can accommodate the volume changes during charge–discharge and improve the electrical conductivity between the NiO nanoparticles. [Copyright &y& Elsevier]

Abstract: Carbon-coated SnO2 nanoparticles were prepared by a novel facile route using commercial SnO2 nanoparticles treated with concentrated sulfuric acid in the presence of sucrose at room temperature and ambient pressure. The key features of this method are the simple procedure, low energy consumption, and inexpensive and non-toxic source materials. As-prepared core/shell nanoparticles were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The electrochemical measurements showed that the carbon-coated SnO2 nanoparticles with 10% carbon and using carboxymethyl cellulose (CMC) as a binder displayed the best electrochemical performance with the highest specific capacity of 502mAhg−1 after 50 cycles at a current density of 100mAg−1. In addition, owing to the water solvability of CMC, the usage of CMC as binder makes the whole electrode fabrication process cheaper and more environmental friendly. [Copyright &y& Elsevier]

Abstract: SnO2 meso-scale tubes were synthesized by anodic electrochemical deposition under ambient conditions. Controlled self-bubbling O2 acted as both the template and the oxidizing agent for obtaining SnO2 tube structures at the interface of the gas (O2) and the liquid (electrolyte). Electrochemical testing showed that the meso-scale tubes have higher discharge capacity and better rate capability than the “microbowls” produced by varying the deposition conditions. From the Arrhenius plot, the apparent activation energies were calculated to be 58.4 and 90.1kJmol−1 for the meso-scale tubes and the microbowls, respectively, indicating that the meso-scale structure allows shorter diffusion routes for the lithium ions or for easier interaction with lithium. [Copyright &y& Elsevier]

Recently, room‐temperature stationary sodium‐ion batteries (SIBs) have received extensive investigations for large‐scale energy storage systems (EESs) and smart grids due to the huge natural abundance and low cost of sodium. The SIBs share a similar "rocking‐chair" sodium storage mechanism with lithium‐ion batteries; thus, selecting appropriate electrodes with a low cost, satisfactory electrochemical performance, and high reliability is the key point for the development for SIBs. On the other hand, the carefully chosen elements in the electrodes also largely determine the cost of SIBs. Therefore, earth‐abundant‐metal‐based compounds are ideal candidates for reducing the cost of electrodes. Among all the high‐abundance and low‐cost metal elements, cathodes containing iron and/or manganese are the most representative ones that have attracted numerous studies up till now. Herein, recent advances on both iron‐ and manganese‐based cathodes of various types, such as polyanionic, layered oxide, MXene, and spinel, are highlighted. The structure–function property for the iron‐ and manganese‐based compounds is summarized and analyzed in detail. With the participation of iron and manganese in sodium‐based cathode materials, real applications of room‐temperature SIBs in large‐scale EESs will be greatly promoted and accelerated in the near future. State‐of‐the‐art high‐abundance and low‐cost metal‐based cathode materials for sodium‐ion batteries are comprehensively summarized and analyzed, providing a step toward the real‐life, commercial application of sodium‐ion batteries. Constructive suggestions and guidance are provided and future prospects regarding this promising field are discussed. [ABSTRACT FROM AUTHOR]

Sodium ion batteries are now attracting great attention, mainly because of the abundance of sodium resources and their cheap raw materials. 2D materials possess a unique structure for sodium storage. Among them, transition metal chalcogenides exhibit significant potential for rechargeable battery devices due to their tunable composition, remarkable structural stability, fast ion transport, and robust kinetics. Herein, ultrathin TiS2 nanosheets are synthesized by a shear‐mixing method and exhibit outstanding cycling performance (386 mAh g−1 after 200 cycles at 0.2 A g−1). To clarify the variations of galvanostatic curves and superior cycling performance, the mechanism and morphology changes are systematically investigated. This facile synthesis method is expected to shed light on the preparation of ultrathin 2D materials, whose unique morphologies could easily enable their application in rechargeable batteries. Ultrathin TiS2 nanosheets are synthesized through a facile exfoliation method by using a shear‐mixing machine. The unique morphology can effectively buffer the volume change and prevent the electrode materials from pulverization, ensuring a long‐life cycling performance. [ABSTRACT FROM AUTHOR]

α-Fe 2 O 3 /reduced graphene oxide (rGO) nanocomposites were successfully synthesized within 15 min through a facile, environmentally friendly microwave hydrothermal method. From field emission scanning electron microscopy and transmission electron microscopy, it can be determined that the α-Fe 2 O 3 nanoparticles, around 50 nm in diameter, are uniformly anchored on the graphene nanosheets. The as-obtained α-Fe 2 O 3 /rGO nanocomposites were applied as anode materials in sodium-ion batteries, which could deliver capacity of ∼310 mAh g −1 after 150 cycles at 100 mA g −1 . [ABSTRACT FROM AUTHOR]

Highlights: [•] A model of TiO2 nanotube arrays growing on Ti mesh was proposed. [•] The TiO2/Ti mesh was used for the anode without current collector or binder required. [•] The capacity of the TiO2/Ti-600min mesh electrode is 1745.5μAhcm−2 over 100 cycles. [•] The TiO2/Ti mesh electrode still maintains its 3D nanostructure after 100 cycles. [Copyright &y& Elsevier]

Abstract: A conducting α-LiFeO2-polypyrrole (α-LiFeO2-PPy) nanocomposite material was prepared by the chemical polymerization method as a cathode material for lithium-ion batteries. The porous α-LiFeO2 was prepared via the microwave hydrothermal method and a post-annealing. The X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy measurements showed that the α-LiFeO2 nanoparticles were coated with PPy. The polypyrrole coating improves the reversible capacity and cycling stability (104mAhg−1 at 0.1C after 100 cycles) for lithium-ion batteries. Even at the high rate of 10C, the electrode showed more than 40% of the capacity at low rate (0.1C). [Copyright &y& Elsevier]

Abstract: LiV3O8–polyaniline nanocomposites have been synthesized via chemical oxidative polymerization directed by the anionic surfactant sodium dodecyl benzene sulfate. The polyaniline particles are uniformly coated on the LiV3O8 nanorods. The composite with 12 wt.% polyaniline retains a discharge capacity of 204 mAh g−1 after 100 cycles and had better rate capability (175 mAh g−1 at 2 C and 145 mAh g−1 at 4 C) than the bare LiV3O8 electrode in the potential range of 1.5–4.0 V. The polyaniline coating can buffer the dissolution into the LiPF6 electrode that occurs in LiV3O8 during cycling. The charge transfer resistance of the composite electrode was much lower than that of the bare LiV3O8 electrode, indicating that polyaniline coating significantly increases the electrical conductivity between the LiV3O8 nanorods. Polyaniline is a conductive binder which buffers the dissolution of LiV3O8 into the electrolyte and reduces the contact resistance among nanorods, so performance of the composite is significantly improved. [Copyright &y& Elsevier]

Abstract: Free-standing single-walled carbon nanotube/SnO2 (SWCNT/SnO2) anode paper was prepared by vacuum filtration of SWCNT/SnO2 hybrid material which was synthesized by the polyol method. From field emission scanning electron microscopy and transmission electron microscopy, the CNTs form a three-dimensional nanoporous network, in which ultra-fine SnO2 nanoparticles, which had crystallite sizes of less than 5nm, were distributed, predominately as groups of nanoparticles on the surfaces of single walled CNT bundles. Electrochemical measurements demonstrated that the anode paper with 34wt.% SnO2 had excellent cyclic retention, with the high specific capacity of 454mAhg−1 beyond 100 cycles at a current density of 25mAg−1, much higher than that of the corresponding pristine CNT paper. The SWCNTs could act as a flexible mechanical support for strain release, offering an efficient electrically conducting channel, while the nanosized SnO2 provides the high capacity. The SWCNT/SnO2 flexible electrodes can be bent to extremely small radii of curvature and still function well, despite a marginal decrease in the conductivity of the cell. The electrochemical response is maintained in the initial and further cycling process. Such capabilities demonstrate that this model hold great promise for applications requiring flexible and bendable Li-ion batteries. [Copyright &y& Elsevier]

Abstract: To reduce the reaction time, electrical energy consumption, and cost, binary α-NiS–β-NiS has been synthesized by a rapid, one-pot, hydrothermal autoclave microwave method within 15min at temperatures of 160–180°C. The microstructure and morphology of the α-NiS–β-NiS products were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). At 140°C, pure hexagonal NiAs-type α-NiS phase was identified from the XRD patterns. With increasing reaction temperature (160–180°C), the XRD evidence indicates that an increasing fraction of rhombohedral millerite-like β-NiS is formed as a secondary phase. The α-NiS–β-NiS sample synthesized at 160°C yielded good electrochemical performance in term of high reversible capacity (320mAhg−1 at 0.1C up to 100 cycles). Even at high rates, the sample operated at a good fraction of its capacity. The likely contributing factor to the superior electrochemical performance of the α-NiS–β-NiS sample could be related to the improved morphology. TEM imaging confirmed that needle-like protrusions connect the clusters of α-NiS particles, and the individual protrusions indicated a very high surface area including folded sheet morphology, which helps to dissipate the surface accumulation of Li+ ions and facilitate rapid mobility. These factors help to enhance the amount of lithium intercalated within the material. [Copyright &y& Elsevier]

Abstract: SnO2-coated multiwall carbon nanotube (MWCNT) nanocomposites were synthesized by a facile hydrothermal method. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The SnO2/MWCNT composites, when combined with carboxymethyl cellulose (CMC) as a binder, show excellent cyclic retention, with the high specific capacity of 473mAhg−1 beyond 100 cycles, much greater than that of the bare SnO2 which was also prepared by the hydrothermal method in the absence of MWCNTs. The enhanced capacity retention could be mainly attributed to good dispersion of the tin dioxide particles in the matrix of MWCNTs, which protected the particles from agglomeration during the cycling process. Furthermore, the usage of CMC as a binder is responsible for the low cost and environmental friendliness of the whole electrode fabrication process. [Copyright &y& Elsevier]

Abstract: Flexible, free-standing, paper-like, graphene-silicon composite materials have been synthesized by a simple, one-step, in-situ filtration method. The Si nanoparticles are highly encapsulated in a graphene nanosheet matrix. The electrochemical results show that graphene-Si composite film has much higher discharge capacity beyond 100 cycles (708mAhg−1) than that of the cell with pure graphene (304mAhg−1). The graphene functions as a flexible mechanical support for strain release, offering an efficient electrically conducting channel, while the nanosized silicon provides the high capacity. [ABSTRACT FROM AUTHOR]

A novel strategy for confined synthesis of graphene wrapped nano-sized LiMn 0.5 Fe 0.5 PO 4 hybrid composite has been developed, including co-precipitation and solvothermal reactions. The LiMn 0.5 Fe 0.5 PO 4 nanoparticles with a constrained diameter of 20 nm are homogeneously wrapped by a continuous interconnected graphene sheets. The mechanism and composite structure evolution during the process are carefully investigated and discussed. With the shortened Li + diffusion paths and enhanced electron conductivity, the hybrid composite shows high discharge capacity and superior rate performance with the discharge capacities of 166 mA h g −1 at 0.1 C and 90 mA h g −1 at 20 C. Excellent cycle stability is also demonstrated with only about 7.8% capacity decay after 500 cycles at 1 C. [ABSTRACT FROM AUTHOR]

A novel tucked flower-like SnS 2 /Co 3 O 4 structure is synthesized by growing Co 3 O 4 in the gaps between petals of SnS 2 microflowers through a facile solution method. In our strategy, the petals of the flowers are curled inwards due to the swelling force resulting from growth of Co 3 O 4 , resulting in the encapsulation of Co 3 O 4 with the SnS 2 petals forming a coating structure. The SnS 2 /Co 3 O 4 composite displays greatly improved performance in comparison with pure SnS 2 . After 100 cycles, an outstanding reversible capacity of ∼715 mAh g −1 with negligible capacity fading is achieved at current density of 100 mA g −1 for SnS 2 /Co 3 O 4 . What is more, the SnS 2 /Co 3 O 4 exhibits excellent rate capability, and a reversible capacity of up to ∼530 mAh g −1 is obtained, even at a current density as high as 1000 mA g −1 . The morphology of tucked flower-like petals and the introduction of the secondary structure of Co 3 O 4 are suggested to be responsible for the improved lithium storage capacity of the composite. The as-prepared SnS 2 /Co 3 O 4 shows promise as a potential anode material for Li-ion batteries due to its simple synthesis method and large capacity. [ABSTRACT FROM AUTHOR]

Lithium-rich layered cathodes are known famously for its superior capacity over traditional layered oxides but trapped for lower initial coulombic efficiency, poorer rate capability and worse cyclic stability in spite of diverse attempts. Herein, a new K-stabilized Li-rich layered cathode synthesized through a simple oxalate co-precipitation is reported for its super electrochemical performances. Compared with pristine Li-rich layered cathode, K-stabilized one reaches a higher initial coulombic efficiency of 87% from 76% and outruns for 94% of capacity retention and 244 mAh g −1 of discharge capacity at 0.5C after 100 cycles. Moreover, 133 mAh g −1 of discharge capacity can be delivered even charged at 10C showing a highly-improved rate capability. X-ray diffraction and electrochemical impedance spectroscopy tests show that enlarged Li slab layer caused by K + accommodation can provide facile Li + diffusion paths and facilitate Li + migration from the crystal lattice. As a consequence, the introduction of K + in the host layered structure can inhibit the detrimental spinel structure growth during cycling. Therefore, the K-stabilized Li-rich layered materials can be considered to be an attractive alternative to meet with the higher power and energy density demands of advanced lithium-ion battery. [ABSTRACT FROM AUTHOR]

Spinel LiMn 2 O 4 is an inexpensive, eco-friendly and highly abundant cathode material for lithium ion batteries. Here, we report a synthesis of nanoporous LiMn 2 O 4 cathode material using a simple vacuum induced self-assembly reaction. Ammonia molecules play a key role in the formation of the nanoporous structure in our method. The galvanostatic charge/discharge results show that the nanoporous LiMn 2 O 4 delivers a high specific capacity at high power rates. About 95.9% of its initial capacity (94.5 mAh g −1 ) is retained after 100 cycles at 10 C. The enhanced kinetics of nanoporous LiMn 2 O 4 with low apparent activation energies indicates that the nanoporous structure provides short Li-ion diffusion paths and a continuous three-dimensional network of pathways for the transport of Li-ions and electrons. These results reveal that the nanoporous spinel LiMn 2 O 4 material is a promising cathode candidate for next generation of high-power lithium ion battery. [ABSTRACT FROM AUTHOR]

Sn/SnO 2 @C composite nanofibers were successfully fabricated by a facile annealing strategy. The composite consists of an amorphous carbon matrix encapsulating carbon nanotubes decorated by ultrafine (<10 nm) SnO 2 nanoparticles, with submicron Sn particles incorporated in the entangled networks of the composite nanofibers. When used as anode material for lithium ion batteries, the Sn/SnO 2 @C composite nanofibers exhibited high initial charge capacity of 756 mAh g −1 at 100 mA g −1 , excellent high-rate capacity of 190 mAh g −1 at 5 A g −1 , and excellent capacity retention of 591 mAh g −1 after 100 cycles at 100 mA g −1 . High-resolution transmission electron microscopy, energy dispersive spectroscopy mapping, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy were applied to investigate the origins of the excellent electrochemical Li + storage properties of Sn/SnO 2 @C. It could be deduced that the ductile carbon matrix and free spaces in the composite nanofiber networks can effectively accommodate the strain of volume change during cycling, prevent the aggregation and pulverization of Sn/SnO 2 particles, keep the whole structure stable, and facilitate electron and ion transport through the electrode. [ABSTRACT FROM AUTHOR]

Porous hierarchical LiMn 0.5 Fe 0.5 PO 4 spheres were synthesized via a novel template-engaged method using pre-synthesized hollow spherical Li 3 PO 4 as template and FeCl 2 ·4H 2 O/MnCl 2 ·4H 2 O as Fe 2+ /Mn 2+ source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the porous hierarchical spheres exhibit hollow structure and have a size distribution of 0.4–1 um consisting of aggregated ∼50 nm nanoparticles. A mechanism of the reaction from Li 3 PO 4 to LiMn 0.5 Fe 0.5 PO 4 was proposed on the basis of the phase and morphology transformation of the intermediates. With the short Li + diffusion path and porous structure, the carbon coated LiMn 0.5 Fe 0.5 PO 4 spheres show high specific capacity and superior rate capability with the discharge capacities of 159.3 mA h g −1 at 0.1C and 80.6 mA h g −1 at 20C. The porous hierarchical spheres also exhibit an excellent cycling stability with about 90.7% of the initial value at 1C after 100 cycles. [ABSTRACT FROM AUTHOR]

Developing advanced electrode materials that deliver high energy at ultra-fast charge and discharge rates are very crucial to meet an increasing large-scale market demand for high power lithium ion batteries (LIBs). A three-dimensional (3D) nanoflower structure is successfully developed in the large-scale synthesis of LiNi 1/3 Co 1/3 Mn 1/3 O 2 material for the first time. The fast co-precipitation is the key technique to prepare the nanoflower structure in our method. After heat treatment, the obtained LiNi 1/3 Co 1/3 Mn 1/3 O 2 nanoflowers (NL333) pronouncedly present a pristine flower-like nano-architecture and provide fast pathways for the transport of Li-ions and electrons. As a cathode material in a LIB, the prepared NL333 electrode demonstrates an outstanding high-rate capability. Particularly, in a narrow voltage range of 2.7–4.3 V, the discharge capacity at an ultra-fast charge–discharge rate (20C) is up to 126 mAh g −1 , which reaches 78% of that at 0.2C, and is much higher than that (i.e., 44.17%) of the traditional bulk LiNi 1/3 Co 1/3 Mn 1/3 O 2 . [ABSTRACT FROM AUTHOR]

Monodisperse porous Ni 0.5 Zn 0.5 Fe 2 O 4 nanospheres have been successfully synthesized by the solvothermal method. The diameter of the nanospheres can be tuned by controlling the reactant concentration. Lower reactant concentration is favoured for the synthesis of mesoporous Ni 0.5 Zn 0.5 Fe 2 O 4 nanospheres with higher surface area. The electrochemical results show that mesoporous Ni 0.5 Zn 0.5 Fe 2 O 4 nanospheres exhibit high reversible specific capacity (1110 mAh g −1 ) for Li storage and high capacity retention, with 700 mAh g −1 retained up to 50 cycles. The excellent electrochemical properties could be attributed to the large surface area and mesoporous structure. The results suggest that Ni 0.5 Zn 0.5 Fe 2 O 4 could be a promising high capacity anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]