Enhanced Electrochemical Performance of Ti‐Doping Li1.15Ni0.47Sb0.38O2 as Lithium‐excess Cathode for Lithium‐ion Batteries

Abstract

Recent success and application of the percolation theory have highlighted cation‐disordered Li‐rich oxides as high energy density cathode materials. Generally, this kind of cathode materials suffer from low cycling stability and rate performance. Doped Ti4+ ions can improve the long‐term cycling stability and rate performance of the Li‐rich oxides materials with obvious capacity fading. The electrochemical performance in LixNi2−4x/3Sbx/3O2 can benefit a lot from the nanohighway, which is a kind of nanoscale 0‐TM diffusion channels in the transition metal layer and provides low diffusion barrier pathways for the lithium diffusion. In this work, the doping effect of Ti on the structure and electrochemical properties in Li1.15Ni0.47Sb0.38O2 is studied. The Ti‐stabilized Li1.15−xNi0.47TixSb0.38O2 (x=0, 0.01, 0.03 and 0.05) have been prepared by a solid‐state method and the Li1.03Ni0.47Sb0.38Ti0.03O2 sample exhibits outstanding electrochemical performance with a larger reversible discharge capacity, better rate capability and cyclability. Synchrotron‐based XANES, combined with ab initio calculations in the multiple‐scattering framework, reveals the Ti ions have been doped into the Li‐site in the lithium layer and formed a distortion TiO6 octahedron. This TiO6 local configuration in the lithium can keep the stability of nanohighway in the electrochemical process. In particular, the Li1.03Ni0.47Sb0.38Ti0.03O2 compound can deliver a discharge capacities 132 and 76 mAh/g at 0.2 and 5 C, respectivly. About 86% capacity retention occurs at 1 C rate after 500 cycles. This work suggests capacity fading in the oxide cathode materials can be suppressed to construct and stabilize the nanohighway.