Composite Polymer Electrolyte Containing Core-Shell Structured SiO2(Li+) Particles for Suppressing Lithium Dendrite Growth and Improving High Temperature Cycling Stability of LiNi0.5Mn1.5O4

Abstract

The most widely used electrolyte for lithium-ion batteries is lithium hexafluorophosphate (LiPF6) in a mixture of organic carbonate solvents due to its high conductivity, good electrochemical stability and acceptable cycle performance at low temperatures [1]. However, the use of liquid electrolytes in lithium batteries has many drawbacks, such as high flammability of organic solvents, possibility of leakage and poor thermal stability [2, 3]. Among the potential electrolytes for lithium batteries, polymer electrolyte has received considerable attention due to high ionic conductivity and superior thermal safety with no electrolyte leakage [4]. However, polymer hosts lose their mechanical strength when they are plasticized with liquid electrolyte solution, leading to serious problems in terms of cycle life and safety [5]. In this study, in order to obtain polymer electrolytes with enhanced mechanical strength and good electrochemical properties, core-shell structured SiO2 nanoparticles containing poly(lithium acrylate) in the shell were synthesized. They were used as functional fillers in preparing composite polymer electrolytes for suppressing lithium dendrite growth and preventing HF generation in the electrolyte. The composite polymer electrolytes prepared with SiO2(Li+) particles exhibited high ionic conductivity, good thermal stability and favorable interfacial characteristics. The lithium metal polymer cells composed of lithium metal negative electrode and LiNi0.5Mn1.5O4 positive electrode are assembled and their cycling performances are evaluated. The cells assembled with the composite polymer electrolyte exhibited superior cycling performance both at ambient temperatures and at elevated temperature.