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Here, a new strategy is reported for the preparation of a new class of nanocomposite anode materials consisting of ppm-level phosphorus-doped Si nanoparticles (P–Si) wrapped in a network of poly-γ-glutamate and graphene. The network produces not only a conductivity-enhanced conduit but also a mechanical stress buffer. The incorporation of poly-γ-glutamate in the nanocomposite enables self-healing capability and maintains the electrode structural integrity. This multifunctionality has significant implications for advancing the design of stable Si-based nanomaterials as high-performance anodes in Li-ion batteries. [ABSTRACT FROM AUTHOR]

Dramatic volumetric variation and poor cyclic stability are great challenges for the practical application of Si anode in lithium-ion batteries. In this work, hierarchical microsized hard carbon-supported Si encapsulated in nitrogen-doped carbon (HC/Si@NC) composites is successfully synthesized via electrostatic self-assembly between an intrinsic negatively charged hard carbon precursor and positively charged Si nanoparticles for the first time. Resorcinol formaldehyde resin sphere synthesized through a low-cost extended Stöber method is used as the carbon core precursor to support Si nanoparticles, followed by carbon coating and carbonization process to further fix Si on the carbon core and enhance the conductivity. The hierarchical structure where Si nanoparticles are tightly anchored onto the carbon core can significantly alleviate the volumetric expansion of Si, and the carbon can enhance the conductivity of the composites. As a result, the as-achieved HC/Si@NC composites exhibit outstanding cycling stability and good structural integrity maintenance. The composites deliver a reversible capacity of 541 mAh g−1 with a capacity retention of 92.1% after 100 cycles at a current density of 0.2 A g−1 and a capacity of 350 mAh g−1 after 300 cycles at a higher current density of 1 A g−1. [ABSTRACT FROM AUTHOR]

A high rate and long life are two crucial factors for next‐generation lithium‐ion batteries (LIBs). Here, we report cylindroid‐like Li4Ti5O12 mesocrystals (CL‐LTO‐MC) obtained by a simple solvothermal reaction and following short thermal annealing process. Owing to the single‐crystal nature and mesoporous structures, CL‐LTO‐MC demonstrates a high specific capacity (174.7 mA h g−1 at 1 C), superior rate performance (145 mA h g−1 at 50 C) and excellent cycling stability (95.5% capacity retention after 3000 cycles at 20 C). Besides, the CL‐LTO‐MC/LiNi0.5Mn1.5O4 full cells also display a remarkable cycle performance with 95.7% capacity retention after 500 cycles at 5 C. These results indicate that CL‐LTO‐MC is a promising anode material for high‐rate and long‐cycling LIBs. [ABSTRACT FROM AUTHOR]

The damage of electrode integrity resulting from large volume change during cycling is the main reason that leads to the fast capacity loss of silicon anodes. Consequently, developing silicon anodes with integrated structure is critical for their practical application. Here, an integrated silicon anode with enhanced cycling ability using polyimide as binder and cyclized polyacrylonitrile as conductive matrix is fabricated by a facile pyrolysis process. The imidization of polyimide and cyclization of polyacrylonitrile are conducted simultaneously during the in situ heat treatment process. Owing to the synergy effect of polyimide binder and conductive polyacrylonitrile which can restrict volume expansion and maintain integrated conducting path effectively, the electrode exhibits a higher initial coulombic efficiency of 83.6% and delivers excellent cycle life with a high reversible capacity of 2362.2 mAh g−1 even after 100 cycles at a current density of 0.1 C, revealing significant improvement in cycle life in comparison with that of Si@cPAN or PI electrode. [ABSTRACT FROM AUTHOR]

Silicon nanoparticles are coated with the conductive polyaniline (PANI) using in situ polymerization method as anode materials to improve the electrochemical performance for lithium ion batteries. At first, the physicochemical and electrochemical properties of the doped polyaniline in the lithium ion electrolyte are investigated. After that, the effect of different contents of PANI for preparing Si/PANI composites on the composition and structure and thus the electrochemical performance are investigated. The structure and morphology of as-prepared materials are characterized systematically by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). It is demonstrated that the silicon/polyaniline composite presents the core/shell structure. The Si/PANI composite with 12.3 wt% PANI exhibits the optimum electrochemical performance. The electrode still maintains better reversible capacity of 766.6 mAh g, and the capacity retention of 72 % is retained after 50 cycles at current density of 2 A g. The good electrochemical properties can be attributed to the PANI-coating layer, which can improve the electrical conductivity of the Si-based anode materials for lithium ion batteries and accommodate the volume change of silicon during the charge-discharge processes. [ABSTRACT FROM AUTHOR]

Abstract: MoO2–graphene composite was synthesized via a two-step of hydrothermal-calcination method. The morphology and structure of the products were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray power diffraction (XRD), and Raman spectroscopy. The content of the graphene in MoO2–graphene composite was examined by thermogravimetric (TG)–differential scanning calorimetry (DSC) analysis. The electrochemical performances of the products were examined by Galvanostatical charge–discharge method, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). When used as anode material for lithium ion batteries, the MoO2–graphene composite shows an enhanced cyclic performance and lithium storage property. The first discharge capacity of the composite can reach 674.4mAhg−1 with a reversible capacity of 429.9mAhg−1. Significantly, the composite can also deliver a reversible capacity of as high as1009.9mAhg−1 after 60 charge/discharge cycles. [Copyright &y& Elsevier]

The core-shell hierarchical mesoporous titanium dioxides with situ nitrogen dopen carbon and the stable architecture are synthesized by a feasible route, basing on the sol-gel, freeze-drying and calcination process. Nitrogen doped carbon is synergistically compounded with nano-TiO 2 to fabricate the hybrid composite (C-N@MP-TiO 2), which has high surface area of 318 m2 g−1 and large average pore size of 6.8 nm. This corresponding anode consisted of the hybrid composite exhibits superior specific capacity, rate capability, and long cycling stability. Also, the initial discharge capacity is up to 360 mAh g−1 at the current density of 0.1 A g−1 with the good capacity retention of 97% after 350 circles. The excellent rate performance presents the capacity of 173.6 mAh g−1 at the current density of 5 A g−1. Moreover, the large current reversible capacity (20 A g−1) can reach 172.2 mAh g−1 with long-term cycling stability over 500 cycles. Therefore, the superior electrochemical performances are attributed to the stable core-shell mesoporous structure and in-situ nitrogen doped carbon, which is not only improve the electron transport and lithium ion diffusion, but also facilitate the immersion of electrolyte. • A hybrid composite with the stable core-shell mesoporous structure and in-situ N doped C was successfully prepared. • The high surface area and large average pore size can fast electrolyte infiltration and shorten Li+ diffusion pathway. • The preparation route firstly based on the sol-gel, freeze-drying and calcination process is feasible. • This hybrid composite displays superior electrochemical performance. [ABSTRACT FROM AUTHOR]

The development of facile and low-cost fabrication methods for silicon/carbon (Si/C) composites with stable cycle performance is urgent requirement for the development of high-energy-density lithium-ion batteries. Exploring carbon materials with good mechanical properties and electrochemical stability for the fabrication of Si/C materials can overcome the extreme volume changes and unstable electrochemical stability of Si anodes. Herein, silicon@sulfur-doped carbon (Si@S-C) composites were successfully synthesized by simple solvent evaporation and carbonization of inexpensive and readily available petroleum pitch (PP) and amorphous sulfur. Various sulfur-containing functional groups enhanced the material strength of composite by increasing the chemical crosslinking of the carbon matrix to adapt to the Si volume changes. In addition, the larger carbon layer spacing and defects derived from sulfur doping can promote Li+ diffusion and electrode reaction. As a result, the optimized Si@S-C142 exhibited stable interfacial electrode stability and moderate cycle performance, delivering a specific capacity of 681.6 mAh·g−1 and 79.1% capacity retention at 0.5 A g−1 after 700 cycles. This synthesis strategy for Si@S-C composites is meaningful for scalable and low-cost fabrication as well as for understanding the effect of sulfur-doped carbon in Si/C anodes. • Silicon@sulfur-doped carbon composites used low-cost raw materials and easy method. • The sulfur-containing functional groups enhance chemical crosslinking to heighten mechanical strength of carbon matrix. • The increasing defects of carbon matrix promote the Li+ diffusion of electrode. • The pore structure of carbon matrix improves the infiltration of electrolyte and buffer function of composites. [ABSTRACT FROM AUTHOR]

The rhombohedral LiSn 2 (PO 4 ) 3 was prepared by solid-state method for the anode material of lithium-ion battery. The effect of pH value of hydrothermal reaction system on the morphology of SnO 2 as the precursor of LiSn 2 (PO 4 ) 3 and the influence of heat-treatment procedure and conditions, such as the sintering temperature and time, on the property of LiSn 2 (PO 4 ) 3 were investigated. The purity, morphology, structure and size distribution of prepared LiSn 2 (PO 4 ) 3 were characterized respectively by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) methods. The results demonstrate that the as-prepared LiSn 2 (PO 4 ) 3 particles exhibit rhombohedral single-crystal structure with an average particle size of 200 nm. The electrochemical measurement results reveal that the as-prepared LiSn 2 (PO 4 ) 3 /C electrode exhibits the improved cycling stability and reversibility with a reversible discharge capacity of 448.6 mA h g −1 at 100 mA g −1 and better rate capability of 332.6 mA h g −1 at 500 mA g −1 . The charge-discharge mechanism of LiSn 2 (PO 4 ) 3 /C electrode was also investigated. According to the test results of cyclic voltammetry, the electrode process includes not only the intercalation and deintercalation of lithium ions in the LiSn 2 (PO 4 ) 3 particles, but also the surface pseudo-capacitive effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel multifunctional nano-silica/carbon hybrid matrix is designed to encapsulate Si nanoparticles in the coating layer. • The n-SiO 2 /C layer is applied to enhance the conductivity, hold the structural integrity, and provides a higher capacity. • The Si-2@n-SiO 2 /C composites demonstrate ideal cycle stability as anode material for lithium-ion batteries. The application of silicon as anode materials for lithium-ion batteries is limited by the huge volumetric expansion and complex synthesis processes. Herein, silicon nanoparticles encapsulated in multifunctional crosslinked nano-silica/carbon hybrid matrix (Si@n-SiO 2 /C) composites are successfully synthesized via simultaneous condensation copolymerization between (3-aminopropyl)-triethoxysilane (APTES) and L-ascorbic acid (L-AA). With the introduction of nano-silica, the multifunctional nano-silica/carbon hybrid matrix can significantly maintain structural integrity during the volume change of silicon, provide a higher capacity than the traditional single carbon coating layer and enhance the conductivity of the materials. Correspondingly, the obtained Si-2@n-SiO 2 /C composites display quite outstanding cycle stability and superior structural integrity maintenance, which delivers a capacity of 800.7 mAh g−1 after 300 cycles at the current density of 1 A g−1. Such a novel coating layer structure design and simultaneous growth of nano-silica/carbon hybrid matrix layer on silicon nanoparticles will provide a simple synthesis strategy for manufacturing high-performance Si-based anode materials. [ABSTRACT FROM AUTHOR]

The well-constructed Si nanostructure anode is essential for achieving high performance lithium-ion battery. In this report, void-buffered Si@TiO 2 /C microspheres are fabricated via a facile solid-liquid adsorption template technology followed by calcination process. Here, for the first time, the green and low-cost TiCl 4 solution is employed as the inorganic titanium precursor for synthesis of size-controllable TiO 2 shell. The void buffer can be controlled by the annealing temperature and concentration of the precursor of template. The Si@TiO 2 /C combines the merits of controllable void for releasing the mechanical stress, robust TiO 2 /C shell for building stable SEI film, high electronic conductivity for improving charge transfer. This specific structure is demonstrated to be effective in alleviating the volume effect during cycling process. When Si@TiO 2 /C microspheres are evaluated as anode of lithium-ion battery, a high reversible specific capacity of 1384 mA h g−1 is obtained after 100 cycles at 200 mA g−1. Even at a high current density of 500 mA g−1, a reversible capacity of 1038 mA h g−1 can still be retained after 400 cycles. The high-capacity electrochemical performance and easy preparation methods demonstrate the Si@TiO 2 /C microspheres are considered as a very promising anode material for next-generation lithium-ion batteries. • For the first time, the inorganic TiCl 4 solution is employed to synthesize size-controllable TiO 2 shell. • The Si@TiO 2 /C combines the merits of controllable void, robust TiO 2 /C shell and high electronic conductivity. • The composite exhibits excellent cycle performance. • The method provides a route for the synthesis of Si and other metal oxides composites. [ABSTRACT FROM AUTHOR]