Waterborne Acrylonitrile Copolymer Binder for 4.5 V High-Voltage Lithium Cobalt Oxide of Lithium-Ion Batteries

Water-based binders in lithium-ion batteries have garnered increasing attention owing to their environmental benignity and cost effectiveness. In this research, a waterborne poly(lithium acrylate-co-acrylonitrile) copolymer, P(LiAA-AN), was prepared and utilized as a high-performance binder for 4.5 V LiCoO2 in a lithium-ion battery. This copolymer binder integrates characteristics of both polyacrylic lithium and polyacrylonitrile. It has the ability to compensate for additional Li ions and engage in the formation of a stable cathode solid electrolyte interface (CEI) on the surface of 4.5 V LiCoO2. Consequently, in comparison with poly(vinylidene fluoride) (PVDF) and LiPAA binders, the water-based P(LiAA-AN) binder leads the 4.5 V LCO/Li battery to superior rate performance and high cycle stability. When the cell was cycled under a current density of 0.5 C (1 C = 185 mAh g–1) and a cutoff voltage of 3.0–4.5 V (vs Li+/Li), a high capacity retention ratio of 91.5% was achieved after 200 cycles. In addition, the P(LiAA-AN) binder demonstrates an excellent electrolyte absorption and a reduced charge transfer impedance. These results substantiate the effectiveness of the P(LiAA-AN) water-based binder in enhancing the electrochemical performance of the high-voltage LiCoO2 cathode.