三功能共晶溶剂添加剂用于高性能锂金属电池

Rational carbonate electrolyte chemistry is critical for the development of high-voltage lithium metal batteries(LMBs).However,the implementation of traditional carbonate electrolyte is greatly hindered by the generation of an unstable electrode interphase and corrosive by-product(HF).Herein,we propose a triple-function eutectic solvent additive of N-methylacetamide(NmAc)with LiNO_(3) to enhance the stability and compatibility of carbonate electrolyte.Firstly,the addition of NmAc significantly improves the solubility of LiNO_(3) in carbonate electrolyte by forming an eutectic pair,which regulates the Li~+solvation structure and leads to dense and homogenous Li plating.Secondly,the hydrolysis of acidic PF_5 is effectively alleviated due to the strong complexation of NmAc with PF_5,thus reducing the generation of corrosive HF.In addition,the optimized cathode electrolyte interphase layer decreases the structural degradation and transition metal dissolution.Consequently,Li||LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)cells with the designed electrolyte deliver superior long-term cycle reversibility and excellent rate capability.This study unveils the rationale for incorporating eutectic solvent additives within carbonate electrolytes,which significantly contribute to the advancement of their practical application for high-voltage LMBs.

3D multicore-shell CoSn nanoboxes encapsulated in porous carbon as anode for lithium-ion batteries

Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nevertheless,the immense volume change during the lithium-ion insert process leads to severe disadvantages of structural damage and capacity fade,which limits its practical application.In this work,a three-dimensional(3 D)multicore-shell hollow nanobox encapsulated by carbon layer is obtained via a three-step method of hydrothermal reaction,annealing and alkali etching.During the electrochemical reactions,the CoSn@void@C nanoboxes provide internal space to compensate the volumetric change upon the lithiation of Sn,while the inactive component of Co acts as chemical buffers to withstand the anisotropic expansion of nanoparticles.Owing to the above-mentioned advantages,the elaborated anode delivers an excellent capacity of 788.2 m Ah/g at 100 m A/g after 100 cycles and considerable capacity retention of 519.2 mAh/g even at a high current density of 1 A/g after 300 cycles.The superior stability and high performance indicate its capability as promising anodes for lithium-ion batteries.