Construction of a Stable LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) Cathode Interface by a Multifunctional Organosilicon Electrolyte Additive

It is still a big challenge to stabilize a Ni-rich cathode interface at high current rate and a long-term cycle in the present Li-ion battery for electric vehicles. In this work, N,O-bis­(trimethylsilyl)­acetamide (BSA) is utilized as a multifunctional electrolyte additive to stabilize the LiNi_0.8Co_0.1Mn_0.1O₂ cathode interface and enhance its electrochemical performance. After 200 cycles, the LiNi_0.8Co_0.1Mn_0.1O₂/Li cell at 1C rate with 0.5% BSA shows improved capacity retention of 86%, while it shows only 69.4% with the baseline electrolyte. When the discharge rate is increased to 2C, the LiNi_0.8Co_0.1Mn_0.1O₂/Li cell with BSA additive shows improved capacity retention of 72.6% after 400 cycles, while the counterpart is only 49.5%. The experimental results show that HF and H₂O can be scavenged by BSA, and the hydrolysis of LiPF₆ is reduced. Moreover, the BSA additive can be preferentially oxidized during the charging process and form a robust, uniform electrode/electrolyte interface film on the NCM811 cathode surface. Consequently, a better CEI film can suppress the electrolyte decomposition, improve cathode interface stability, and alleviate transition metal ions dissolution.