Optimized Temperature Effect of Li-Ion Diffusion with Layer Distance in Li(Ni_xMn_yCo_z)O_2 Cathode Materials for High Performance Li-Ion Battery

摘要

Understanding and optimizing the temperature effects of Li-ion diffusion by analyzing crystal structures of layered Li(NixMnyCoz)O-2 (NMC) (x + y + z = 1) materials is important to develop advanced rechargeable Li-ion batteries (LIBs) for multi-temperature applications with high power density. Combined with experiments and ab initio calculations, the layer distances and kinetics of Li-ion diffusion of LiNixMnyCozO2 (NMC) materials in different states of Li-ion de-intercalation and temperatures are investigated systematically. An improved model is also developed to reduce the system error of the Galvanostatic Intermittent Titration Technique with a correction of NMC particle size distribution. The Li-ion diffusion coefficients of all the NMC materials are measured from -25 to 50 degrees C. It is found that the Li-ion diffusion coefficient of LiNi0.6Mn0.2Co0.2O2 is the largest with the minimum temperature effect. Ab initio calculations and XRD measurements indicate that the larger Li slab space benefits to Li-ion diffusion with minimum temperature effect in layered NMC materials.