Crystal structure, solid phase diffusion path and coefficient of Zr-doped Li4Ti5O12

Abstract

The influences of the crystal structure of Zr-doped lithium titanate prepared by the sol–gel method on the lithium ion diffusion coefficient and rate performance were studied. Compared with the pure phase Li4Ti5O[Formula: see text], Zr-doped lithium titanate presented a high discharge capacity as well as a good rate performance and cycle performance, and Li4Zr[Formula: see text]Ti[Formula: see text]O[Formula: see text] yielded the best electrochemical performance. Li4Zr[Formula: see text]Ti[Formula: see text]O[Formula: see text] possessed capacities of 162 (1st) and 143 (100th) mAh g[Formula: see text] at 5[Formula: see text]mA[Formula: see text]cm[Formula: see text] with [Formula: see text]100% of the coulombic efficiency. The area of the migration surface of Li4Ti5O[Formula: see text] is proportional to the square of the lattice constant, so Li4Zr[Formula: see text]Ti[Formula: see text]O[Formula: see text] demonstrated the largest migration surface with 8.3600 Å of “[Formula: see text]”. The larger the migration surface is, the lower the activation energy for lithium ion migration is, and the easier it is for lithium ions to diffuse and migrate.