Polyimide/carbon black composite nanocoating layers as a facile surface modification strategy for high-voltage lithium ion cathode materials

Ion-conductive polyimide (PI)/electron-conductive carbon black (CB) composite nanocoating layers (referred to as "PI/CB coating layers") are presented as a facile and scalable surface modification strategy for high-voltage lithium ion cathode materials (here, LiCoO₂ (LCO) is chosen as a model system). The PI/CB coating layers exhibit a unique synergistic effect (i.e., boosted electronic conduction (from CB networks) in conjunction with suppression of unwanted interfacial side reactions between delithiated LCO and the liquid electrolyte (due to PI nanothin films)), which thus exerts a beneficial influence on the electrochemical performance and thermal stability of high-voltage cells.