Enhancing High-Voltage Cycling Stability of LiCoO₂ via a Cyclized Polyacrylonitrile Coating

Abstract

High voltage (4.6V) is a crucial method for enhancing the specific capacity of lithium cobalt oxide (LiCoO₂, LCO) materials; however, this approach significantly compromises their stability. In this study, the cPAN-LCO-3 material was prepared by a simple solvothermal method and then subjected to heat treatment cyclized polyacrylonitrile (cPAN). The capacity retention rate of the cPAN-LCO-3 after 100 cycles reached 80.1% with a voltage range of 3-4.6V at 0.5C, while the pristine LCO only maintained 50.6%, this is because the robust and conductive core-shell structure effectively acts as a physical barrier, inhibiting "hexagonal-monoclinic-hexagonal" phase transition process of the pristine LCO, thereby enhancing the cycling stability. At the same time, it significantly improves the discharge specific capacity and rate performance of LCO at 4.6V, with its discharge specific capacity reaching 219.0 mAh g⁻¹ at 0.1C, which is higher than the discharge specific capacity of the pristine LCO (204.2 mAh g⁻¹), this is due to the graphenelike cPAN (shell) structure coating enhances the rapid transfer of charges and the rapid conduction of Li + .