SnSe/Cu2SnSe3 Heterojunction Structure with High Initial Coulombic Efficiency for Lithium-Ion Battery Anodes

Due to high theoretical specific capacity and abundant reserves, tin selenide-based materials have received tremendous attentions in the fields of lithium-ion batteries. Nevertheless, the huge volume changes during insertion/de-intercalation processes deteriorate the Coulombic Efficiency greatly. In order to solve it, the researchers have made great efforts by means of controlling nanoparticles granularity, carbon coating, ion doping et al. In this study, SnSe/Cu2SnSe3 heterojunction nanocomposites were synthesized by solvo-thermal method. The resulting SnSe/Cu2SnSe3 is a three-dimensional flower-like hierarchical nanostructure composed of nanoscale thin lamellae of a thickness of 8-12 nm. The unique nanostructure could shorten the diffusion path of lithium ions and expedite charge transfer, and therefore enhance the reaction kinetics. Compared with SnSe, the initial Coulombic efficiency of SnSe/Cu2SnSe3 is raised from 59% to 90% as the anode material of lithium-ion batteries.

Recent Progress in Presodiation Technique for High-Performance Na-Ion Batteries

Na-ion batteries (NIBs) have been attracting growing interests in recent years with the increasing demand of energy storage owing to their dependence on more abundant Na than Li. The exploration of the industrialization of NIBs is also on the march, where some challenges are still limiting its step. For instance, the relatively low initial Coulombic efficiency (ICE) of anode can cause undesired energy density loss in the full cell. In addition to the strategies from the sight of materials design that to improve the capacity and ICE of electrodes, presodiation technique is another important method to efficiently offset the irreversible capacity and enhance the energy density. Meanwhile, the slow release of the extra Na during the cycling is able to improve the cycling stability. In this review, we would like to provide a general insight of presodiation technique for high-performance NIBs. The recent research progress including the principles and strategies of presodiation will be introduced, and some remaining challenges as well as our perspectives will be discussed. This review aims to exhibit the basic knowledge of presodiation to inspire the researchers for future studies.

Investigating on physical and electrochemical properties of high concentrated electrolytes based on LiBF4 salt for 5 V Li-ion rechargeable batteries

In this work, highly concentrated electrolytes were prepared by dissolving tetrafluoroborate (LiBF4) salt in the two solvents including tetramethylene sulfone (TMS) and trimethyl phosphate (TMP) with different mole ratios. The results indicated that the electrolyte LiBF4/TMS (1:3) (~3.4 M) possessed the highest oxidation stability of 6.2 V (vs. Li+/Li) and high ionic conductivity of 1.0 mS/cm that could be promising for high voltage Li-ion batteries operated in the voltage range of 3.5-4.9 V. The electrolyte compatibility with high voltage cathode Li || LiNi0.5Mn1.5O4 (LNMO) was evaluated in coin-cell configuration, which displayed high reversible discharge capacity of 113 mAh/g in the first cycle and high initial Coulombic efficiency >91% and remained >80% of the initial capacity at the 100th cycle. By using the cyclic voltammetry (CV) method, the diffusion coefficient was also calculated as about 4.51×10-11 cm2/s.