Interfacial Regulation of a 4.5 V LiCoO₂-Based Battery via Advanced Slurry Additive Modification

Lithium cobalt oxide (LCO) remains the predominant cathode for consumer electronics, owing to its superior volumetric energy density and theoretical capacity. However, extending its operating voltage beyond 4.5 V triggers aggressive electrolyte decomposition, leading to structural deterioration and rapid performance decay. To address this challenge, we propose a functionalized polyester-diacrylate-polydimethylsiloxane (PAPDMS) as a slurry additive, forming a protective layer. This layer plays a crucial role in improving electronic conductivity, enhancing mechanical flexibility, and facilitating electrolyte uptake of LCO. In particular, this protective layer not only modulates the solvation structure, thereby promoting the formation of an inorganic-rich CEI, but also effectively suppresses the dissolution of transition metals. The dual-effect synergy of the PAPDMS layer on both the electrode and electrolyte significantly enhances LCO stability at 4.5 V. Compared with the original LCO, the modified LCO shows an increase in capacity retention rate from 62.3% to 85.2% after 200 cycles at 4.5 V. Moreover, in a practical graphite||LCO pouch cell, the PAPDMS-modified LCO demonstrates superior long-term stability with 78.2% capacity retention after 500 cycles, dramatically outperforming pristine LCO electrodes (46.8%). This strategy presents a scalable approach to stabilizing high-voltage LCO in next-generation lithium-ion batteries.