Study On Solid Polyester Electrolyte In Lithium-ion Battery

The solid-state lithium-ion battery can meet the requirements of high energy density and safety performance.It is one of the most promising chemical energy storage equipment and has been widely studied.The solid electrolyte is one of the important components of the battery,which can be divided into inorganic solid electrolytes and polymer solid electrolytes.The inorganic solid electrolyte has poor contact with the electrode interface and poor processing performance,which is difficult for commercial production.Polymer solid electrolyte has the advantages of good flexibility,excellent processability,and a wide electrochemical stability window.So,it is most expected to replace the traditional liquid electrolyte and be applied to all solid lithium metal batteries.Due to the excellent electrochemical stability,easy processability and stable contact with Li metal,solid polymer electrolytes can effectively improve the energy density of Li metal batteries.In this work,the preparation and electrochemical properties of two types of solid-state polymer electrolytes were investigated.The main contents are as follows:（1）The effect of lithium salt content of polyoxalate electrolytes was explored.At 35 ^oC,the conductivity of polyheptyl oxalate polymer electrolyte was the highest,reaching 1.27×10^-5 S cm^-1.Introducing fluorine element into its end groups and its electrochemical window can reach 5 V.The Li Ni_0.8Co_0.1Mn_0.1O₂/Li battery was assembled,and the battery discharge capacity can reach 191.0 m Ah g^-1.Meanwhile,after 80 cycles,the capacity retention rate of 76.4%.（2）The effect of lithium salt content of polycarbonate electrolyte was explored.Because of the low conductivity of polybutylene carbonate polymer electrolyte,the conductivity of polybutylene carbonate polymer electrolyte was improved by adding succinonitrile.In addition,Fluorine was introduced into the end groups of polybutylene carbonate,and its electrochemical window reached 5.2 V.