An upper limit of Cr-doping level to Retain Zero-strain Characteristics of Li4Ti5O12 Anode Material for Li-ion Batteries

Abstract

Since Li4Ti5O12 as a promising anode material in lithium-ion batteries (LIBs) has a poor rate performance due to low electronic conductivity, a doping of Li4Ti5O12 with heterogeneous atoms has been considered to overcome this problem. Herein, we report that there is an upper limit of doping level to maintain the zero strain characteristics of Li4Ti5O12 lattice during charge/discharge process. By using synchrotron studies, it was revealed that the Li+ diffusivity was maximized at a certain doping level for which the conductivity was markedly increased with maintaining the zero strain characteristics. However, with more doses of dopants over the upper limit, the lattice shrank and therefore the Li+ diffusivity decreased, although the electronic conductivity was further increased in comparison with the optimal doping level.