Core–shell-structured Li[(Ni)_0.5(Ni_0.7Co_0.3)_0.5]O₂ cathode material with high capacity and rate performance for high-energy Li-ion batteries

Abstract

The poor cycle performance and rate capability of LiNiO₂ limit its practical applications. Improving the rate performance of the core (LiNiO₂) using a shell (LiNi_0.7Co_0.3O₂) to protect it from side reactions with the electrolyte and its unstable structure at high voltages is essential. Electrochemical test results showed that the discharge capacity of the core–shell was 152.5 mA h g⁻¹ (64.9%) at 10 C (1700 mA g⁻¹), which indicated a 29.9% improvement in high-rate performance compared to the core with a discharge capacity of 117.4 mA h g⁻¹ (52.4%). The core–shell showed a high discharge capacity retention rate of 96.0% after five charge and discharge cycles at 10 C. In addition, the charge transfer resistance of the core–shell at 4.5 V after the first cycle was 218.81 Ω, which showed a decrease in resistance of approximately 55% compared to the resistance of the core (395.52 Ω). The electrochemical test results indicated that the shell coating increased the structural stability by inhibiting side reactions with the electrolyte.