Optimized Temperature Effect of Li-Ion Diffusion with Layer Distance in Li(NixMnyCoz)O2 cathode Materials for High Performance Li-Ion Battery

Abstract

Understanding and optimizing temperature effects of Li-ion diffusion by analyzing crystal structures of layered Li(NixMnyCoz)O2 (NMC) (x + y + z = 1) materials are 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 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 “Galvanostatic Intermittent Titration Technique” (GITT) with a correction of NMC particle size distribution. The Li-ion diffusion coefficients of all the NMC materials are measured from -25 to 50 °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 is benefited to Li-ion diffusion with minimum temperature effect in layered NMC materials. Figure 1