Research on Electrochemical Properties and Fade Mechanisms of Li-rich Cathode Materials at Low-temperature

In recent years, Li-rich layered cathode materials have caught more and more attention; however, their low-temperature performance have hardly been researched and reported. In this work, typical layered Li-rich oxides (0.55Li(2)MnO(3)center dot 0.45LiNi(1/3)Co(1/3)Mn(1/3)O(2)) are successfully synthesized by co-precipitation method. And their electrochemical properties have been investigated emphatically at 25 degrees C and 0 degrees C. Results show that the reversible capacity of as-prepared Li-rich oxides exhibit much dependence on temperature from similar to 230 mAh.g(-1) (25 degrees C), similar to 160 mAh.g(-1) (10 degrees C), similar to 70 m mAh.g(-1) (0 degrees C) to similar to 50 mAh.g(-1) (similar to 5 degrees C). Our analyses indicate that there are several factors responsible for the capacity loss at low temperature: (1) the deactivation of Li2MnO3 component; (2) the limited kinetic of Li+ intercalation into MnO2; (3) the increase of electrochemical impendences, especially the charge-transfer resistance (R-ct); (4) the decrease of Li ion diffusion coefficient (DLi+). And we find that pre-activation at room temperature is a quite effective way to improve its electrochemical performances at low temperature. In addition to the above four factors, for the first time, we suggest that the lattice contraction with decreasing temperature should also be considered. (C) 2016 Elsevier Ltd. All rights reserved.