Zirconium(IV) Doping Enlarging Lithium-Ion Diffusion Channel of Lithium-Rich Li2.24SrTi6O14Anode Material for High-Rate Lithium-Ion Batteries

Abstract

As a titanium-based anode material, Li2SrTi6O14 (LSTO) has good rate performance and a lower potential (1.4 V vs Li+/Li) than Li4Ti5O12; hence, LSTO is considered to be a promising anode for power type lithium-ion batteries (LIBs). However, the large particle size and low Li+ diffusion coefficient of LSTO may deteriorate its high-rate charge–discharge performance. In this work, Li-rich Li2.24SrTi6–xZrxO14 materials with different Zr-doping amounts (x = 0, 0.05, 0.1, 0.2) were synthesized by a solid-state method. X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area measurement, a LAND battery testing system, and galvanostatic intermittent titration technique (GITT) were used to study the effect of Zr4+ doping on the properties of Li2.24SrTi6O14. Zr4+ doping can effectively inhibit the grain growth, improve the diffusion coefficient of Li+ in the material, and enhance the high-rate charge–discharge performance. The optimum doping ratio of Li2.24SrTi6–xZrxO14 is x = 0.1, in which case the capacity retention at 10C/1C can reach 82.9%. Excessive Zr4+ doping is harmful to the capacity and rate performance of the anode. This work provides a feasible path for the improvement of the anode material of LIBs by the doping of transition metals.