Artificial interface stabilized LiNi0.80Co0.15Al0.05O2@Polysiloxane cathode for stable cycling lithium-ion batteries

Abstract

LiNi0.80Co0.15Al0.05O2 (NCA) as a practical cathode material for lithium-ion batteries has been attracting extensive attention owing to its superior specific capacity and small voltage hysteresis, but suffers from the serious side reactions with electrolyte and HF erosion resulting in capacity fading. A thin conformal polysiloxane with ethoxy-functional groups (EPS) is successfully grown on NCA particles through the hydrolysis-condensation method effectively suppresses the side reactions and mitigates the instability of NCA cathode. The original discharge capacities of NCA and NCA-EPS cathodes are 158 and 159 mAh g−1 at 25 °C, respectively. The capacity retention of NCA-EPS cathode is ~96% of the original capacity after 150 cycles under 1 C, 25% higher than NCA cathode. Even at 55 °C, NCA-EPS cathode could maintain ~86% of the original discharge capacity through 150 cycles, which enhances 29% compared to NCA cathode. The excellent cycling stability of NCA originates from the EPS that acts as a protective shell to reduce the trace water on the NCA surface, inhibit the side reaction and remove HF from the electrolyte through a nucleophilic substitution reaction.