Interfacial Kinetics Induced Phase Separation Enhancing Low-Temperature Performance of Lithium-Ion Batteries

Understanding the temperature dependence of phase transitions occurred in electrode materials is crucial for improving the low-temperature performance of Li-ion batteries. In this work, we find an unusual temperature dependence in the phase transition of TiO2 nanoparticles on dynamic Li+ intercalation, with a decrease in temperature resulting in the formation of a supersaturated solid solution phase. Kinetic analyses reveal that Li redistribution is facilitated at high temperature while limited at low temperature. This difference manifests as a thermodynamically-controlled phase separation at high temperature and a kinetically-controlled formation of a supersaturated solid solution phase at low temperature. Facilitating the phase separation by enhancing the interfacial kinetics proves effective to improve the low-temperature performance. This study provides a comprehensive and in-depth understanding of the temperature dependence of the lithiation-induced phase transition, which has important implications for the development of the next generation of all-climate rechargeable batteries. © 2020