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

Ni-rich layered LiNi0.8Co0.1Mn0.1O2(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 situadjusting heat and deformation as well as reducing side reactions and boosting ion transport. NCM811 modified with 3 wt % LiZr2(PO4)3can 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)3were discussed. The concept holds excellent promise for other energy materials with a high heat effect or low ion transport.