Combining Deformation, Heat, and Ionic Conductivity to Improve the Electrochemical Performance and Safety of Li-Ion Batteries under Extreme Conditions

Ni-rich layered LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) is highly attractive for high-energy batteries, but it still faces some challenges like cyclability, rate performance, and safety caused by deformation and heat. To improve the performance of NCM811, a negative thermal expansion (NTE) material, LiZr₂(PO₄)₃, with high ionic conductivity was adopted by in situ adjusting heat and deformation as well as reducing side reactions and boosting ion transport. NCM811 modified with 3 wt % LiZr₂(PO₄)₃ can retain 162.2 mAh/g as the current rate increases to 5.0C at 25 °C, and the value reaches 177.7 mAh/g at 60 °C after 100 cycles at 1.0C, around 17.0% higher than that of NCM811. The strain and released heat of NCM811 are, respectively, decreased by about 44.2 and 32.6%, while the Li⁺ diffusion coefficient is increased by about 300%. Combining multifarious analysis results using different techniques, enhancement mechanisms of NCM811 by LiZr₂(PO₄)₃ were discussed. The concept holds excellent promise for other energy materials with a high heat effect or low ion transport.