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Abstracts Silicon (Si) is regarded as one of the most promising anode materials for Li-ion batteries due to its high theoretical specific capacity (4200 mAh g −1 ). To overcome the poor cycling stability issue associated with its low conductivity and large volume changes (∼300%) during charge/discharge processes, a novel approach to fabricate three-dimensional (3D) network structure of silicon-graphene-polyaniline (Si-G-PANI) has been developed. During this synthetic, the graphene sheet was first coated on the surface of Si from a pyrolysis reaction of the liquid-polyacrylonitrile (LPAN), which not only improves conductivity but also constrains the serious mechanical stress caused by the volume expansion of Si. Subsequently, Si-G-PANI composite was obtained through an in-situ polymerization, the PANI layer is tightly bounded to graphene owing to an enhancement of π conjugation between the PANI and graphene-grafted Si nanoparticles. Herein, PANI layer offers a 3D conductive and protective network to allow the volume variation of Si during cycling, as well as facilitate the electron and lithium ion transfer processes. With the dual protection of graphene and PANI, the Si-G-PANI electrode can deliver a reversible specific capacity of 1001.8 mAh·g −1 at a current density of 1.5 A g −1 after 50 cycles. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, modifying cathode materials' surfaces become a popular pursuit. This paper reveals a novel spinel LiMn2O4 in situ coated with graphene-like membrane prepared using liquid-polyacrylonitrile (LPAN) as the carbon source. The structure and electrochemical performance of graphene-like membrane-coated spinel LiMn2O4 are investigated systematically. The membrane has a typical graphene-like layer carbon structure that can be applied the LiMn2O4 particles' surfaces in situ without affecting their crystal structure. Moreover, the graphene-like membrane helps to increase the particle size. The electrochemical performance reveals that coating the graphene-like membrane in situ significantly improves the discharge capacity and cycling stability of the spinel LiMn2O4. In particular, the spinel LiMn2O4 coated with a calcined 20 wt% LPAN graphene-like membrane in situ reached 131.1 mAh g−1 at room temperature, and up to 96% capacity is retained after 50 cycles at 0.1 C. The cyclic voltammetry and electrochemical impedance spectra analyses indicate that the graphene-like membrane does not influence the insertion or desertion of Li+. The improved electrochemical performance is attributed to the decreased manganese dissolution in the electrolyte and the smaller charge transfer resistance generated by the graphene-like membrane coating. [Copyright &y& Elsevier]

With the impetus to accelerate worldwide market adoption of electrical vehicles and afford consumer electronics with better user experience, advancing fast-charging technology is an inevitable trend. However, current high-energy lithium-ion batteries are unable to support ultrafast power input without any adverse consequences, with the capacity fade and safety concerns of the mainstream graphite-based anodes being the key technological barrier. The aim of this review is to summarise the fundamentals, challenges, and solutions to enable graphite anodes that are capable of high-rate charging. First, we explore the complicated yet intriguing graphite–electrolyte interface during intercalation based on existing theories. Second, we analyse the key dilemmas facing fast-charging graphite anodes. Finally, some promising strategies proposed during the past few years are highlighted so as to outline current trends and future perspectives in this field. [ABSTRACT FROM AUTHOR]

The coordination environment of Li+ is adjusted by introducing FEC and the solvation structure of Li+ in the flame-retardant electrolyte is reshaped simultaneously. Furthermore, the higher LUMO energy level of FEC facilitates the formation of firm and dense SEI on the surface of the Gr electrode. The in-situ induced stable interface of this novel solvated structure not only suppresses the co-intercalation effect of TMPa solvent, but also enhances the even Li+ transport, contributing to the stable cycling of Li|Gr cells. [Display omitted] • A flame-retardant electrolyte with FEC involved in Li+ solvated structure is proposed. • In-situ induced LiF-rich SEI promotes structural integrity of graphite electrodes. • The modified Li|Gr cell delivers an excellent cycling performance for 300 cycles with 97.48% capacity retention. Conventional electrolytes with flammability and volatility may incur severe safety issues, which are impeding the application of lithium batteries on a large scale. Flame-retardant solvents are introduced into the electrolytes to enhance the security performance, while the battery electrochemical performance is compromised due to incompatibility between these solvents and graphite (Gr) anode. In this work, a flame-retardant electrolyte prepared by trimethyl phosphate (TMPa), lithium difluoro(oxalato)borate (LiDFOB) and fluoroethylene carbonate (FEC) could be expected to solve the dilemma via regulating the solvation structure of Li+ to suppress the co-intercalation effect of TMPa with Li+ and alleviate the compatibility issues of interface caused by the continuous reduction of LiDFOB. The formation mechanism of the solid electrolyte interface (SEI) at the graphite electrode was analyzed to explore the intrinsic reaction of the electrolyte at the electrode interface. The 300-cycle capacity retention of Li|Gr cell at 0.5C reaches 97.48 %, and the deposition and stripping performance of the Li|Li symmetric cell is also significantly improved. Such Li+ solvation structure modification provides a new idea for fire-extinguishing electrolyte design and helps to promote the industrialization of safe and eco-friendly electrolytes. [ABSTRACT FROM AUTHOR]

Li 4 Ti 5 O 12 particles are synthesized coated with very thin graphene-like sheets in situ using liquid-polyacrylonitrile (LPAN) as the carbon source and added utilized conductivity additives to improve the conductivity of the electrode materials. The crystalline structures of Li 4 Ti 5 O 12 with 20% LPAN and different conductivity additives composites were examined by XRD. The structure and electrochemical performance of the graphene-like sheets coated Li 4 Ti 5 O 12 , with conductivity additives added, was systematically investigated. The electrochemical performance also revealed that the graphene-like sheets significantly improved the discharge capacity and cycling stability of Li 4 Ti 5 O 12 . In particular, the coated Li 4 Ti 5 O 12 with 20 wt% LPAN and 1% acetylene black (CB) reached 166.2 mAh g −1 at 10C. The performance improvement is a result of the graphene-like nanosheet conformal coating, which creates an electrically conductive network for the electrode. [ABSTRACT FROM AUTHOR]

This paper reveals a novel Li-rich layered cathode material Li[Li 0.1 Ni 0.45 Mn 0.45 ]O 2 in situ coated with graphene-like carbon prepared by using liquid-polyacrylonitrile (LPAN) as the carbon source. The structure and electrochemical performance of graphene-like carbon coated Li[Li 0.1 Ni 0.45 Mn 0.45 ]O 2 are investigated systematically. The results demonstrate that the graphene-like carbon are in situ coated tightly on the surface of Li[Li 0.1 Ni 0.45 Mn 0.45 ]O 2 particles. The in-situ coating of graphene-like carbon significantly improves the electrochemical properties of cathode materials. The discharge capacity of cell made of 12wt% LPAN-coated Li[Li 0.1 Ni 0.45 Mn 0.45 ]O 2 can reach 210 mAh g −1 and the capacity retention is close to 100% after 50 cycles at 0.1C. The cyclic voltammgram and electrochemical impedance spectra analyses further demonstrate that the improved electrochemical performance of LPAN-coated Li[Li 0.1 Ni 0.45 Mn 0.45 ]O 2 cathode materials is attributed to the graphene-like carbon in situ coating, which can protect the cathode directly contact with the electrolyte. Therefore, the Li-rich layered Li[Li 0.1 Ni 0.45 Mn 0.45 ]O 2 in situ coated with graphene-like carbon is a very good promise cathode material for advanced LIB with high capacity and good stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A universal, facile and ultrafast precipitation polymerization method is developed. • Dual-aldehyde monomers are adopted to prepare hierarchical polymer particles. • Without using templates, hydrothermal devices, surfactants and catalysts. • The preparation process just cost 10 minutes. • Representative WBL carbon microsphere anodes exhibit high performance for LIBs. Hierarchical polymer architectures have attracted considerable attention owing to their crucial roles in catalysis, drug delivery, biology, electronics and energy storage fields. Unfortunately, the current synthesis of polymer particles with hierarchical structures mainly relies on templates, hydrothermal devices, surfactants, and catalysts approaches that have the disadvantages of time-consuming procedures, complex manufacturing processes, high cost, the use of toxic agents (e.g. HF acid for templates removal) and potential risk of explosion (hydrothermal methods). Herein, for the first time, we have developed an ultrafast template-free, hydrothermal-free, surfactant-free, and catalyst-free precipitation polymerization method to synthesize a diversity of polymer particles with multi-dimensional (0D, 1D, 2D and 3D) hierarchical structures simply from polymerization of common dual-aldehyde and amino monomers at room temperature, and the fabrication process only took 10 min. After carbonizing one typical polymer particles (wool-ball-like structure) as an application example, we further tested the electrochemical performance of the as-obtained typical structures and the results show a reversible lithium-ion storage capacity of 226.5 mAh g−1 after 3200 cycles at the current density of 5 A g−1. Our technique provides a cost-effective, rapid, scalable, and green approach to prepare multi-dimensional hierarchical polymer structures and paves the way towards their application in a diversity of emerging fields. [ABSTRACT FROM AUTHOR]

• A material composed of MoS 3 and MXene is proposed by an electrostatic self-assembly. • MoS 3 exhibits impressive electrochemical performance in LIBs and in LSBs. • Ex-situ XPS was used to explore the electrochemical mechanism both of LIBs and LSBs. • We conceived the mechanism of LIBs and adsorption and catalytic mechanism of LSBs. The development of electrode materials with the synergistic effects of good chemical stability and high electrical conductivity has improved the sluggish ion kinetics and severe capacity degradation of rechargeable lithium batteries. Herein, a multifunctional heterostructure material (MoS 3 -Ti 3 C 2 T x) comprising a functionalized MXene (Ti 3 C 2 T x) and amorphous MoS 3 is prepared by a scalable electrostatic self-assembly method. Remarkably, as lithium-ion battery anodes, the resultant MoS 3 -Ti 3 C 2 T x not only exhibits increased electrochemical activity, accelerated lithium-ion diffusion and fast charge transfer kinetics but also shows high specific capacity, excellent rate performance and long-term cycling stability. By virtue of these merits, MoS 3 -Ti 3 C 2 T x offers an excellent reversible capacity of 1043 mAh g−1 at 200 mA g−1 and exhibited a capacity of 568 mAh g−1 at a current density of 2 A g−1 after 1000 cycles. When acting as the cathode for lithium-sulfur batteries, the amorphous MoS 3 anchored on MXene demonstrates high capture and catalytic activity towards polysulfide conversion. Accordingly, the optimized electrode exhibits a capacity of 836 mAh g−1 at 0.2C after 100 cycles and a satisfactory rate performance of 463 mAh g−1 at 2C after 400 cycles. Moreover, the associated conversion mechanism is studied by ex situ XPS. These results demonstrate that heterostructure composites constructed by an amorphous sulfide and surface functionalized MXene are feasible electrode materials for both lithium-sulfur batteries and lithium-ion batteries. [ABSTRACT FROM AUTHOR]

• High-performance heterostructure MoS 2 @SnS-QDs/CNN anode material is facile prepared. • The synergistic coupling effect among the different components is clearly revealed. • MoS 2 @SnS-QDs/CNN displays high discharge performance and excellent cycle stability. • The Li+ ions storage mechanism is investigated by in-situ XRD, ex-site XPS/SEM. • A full cell is also successfully fabricated to study the practical application. Transition metal sulfides have high abundance and large theoretical capacities are considered to be an effective candidate for advanced electrodes of lithium ion batteries (LIBs). Here, a large-scale and controllable method was used in synthesizing ultrathin MoS 2 nanosheets anchored on 3D hierarchical nanohybrids with SnS quantum dots, which are decorated on a carbon nanosheet network (MoS 2 @SnS-QDs/CNN). The 3D cross-linked carbon nanosheet not only could prevent SnS from being directly exposed to the electrolyte but also retained the structural stability of the electrode. Moreover, the MoS 2 nanosheets exposed active sites to carry lithium ions. A heterojunction was formed at the interface owing to the close contact between molybdenum disulfide and SnS and greatly increased charge carrying and lithium storage capacities. Benefiting from these structural advantages, the MoS 2 @SnS-QDs/CNN electrodes showed outstanding electrochemical and long-term cycling performance owing to their unique structures and amazing synergies. As a half-cell anode material, MoS 2 @SnS-QDs/CNN-2 provided a reversible capacity of 713 mAh g−1 after 1000 cycles at a current density of 2 A g−1. When assembled into a full battery, it still provided 491 mAh g−1 at a current density of 1 A g−1 after 100 cycles. At the same time, a small LED bulb was lit for a while. This advanced material has great potential in other applications, such as supercapacitors, catalysis, and sensors. [ABSTRACT FROM AUTHOR]