Design of double layer cathode electrode for improving the safety and stability of lithium-ion batteries

LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) is a widely used cathode material for lithium-ion batteries (LIBs). However, the poor cycle performance and safety issue remains a huge challenge for its practical applications. Here we show a simple double layer strategy to improve the electrochemical characteristics and safety performance. NCM was coated by LiFePO₄ (LFP), a safe cathode material with long cycle stability, exhibited more excellent cycling stability and similar rate properties at room temperature (called NCM/LFP). Under 45 ℃, the NCM/LFP (6:1)||graphite pouch cell shows excellent 83% capacity retention after 600 cycles at 1C, which compared to the sharp attenuation of pristine NCM. Furthermore, NCM/LFP (6:1)||graphite cell could pass the nail penetration tests and the thermal runaway temperature (T_TR) delayed by 193℃, which proved the double layer design has better safety performance. The current work might pave an avenue for cathode materials, as a sustainable solution to high energy density LIBs for applications.