Synergy effects of Tb/Y/Zn for structural stability of high-voltage LiCoO2 cathode material

Abstract

As a popular cathode material in rechargeable lithium-ion batteries, lithium cobalt oxide (LiCoO2) is required to achieve high-level safety with high energy density to meet the ever-increasing energy demand for energy storage devices. The method of lifting the operating voltage of LiCoO2 to release more capacity for higher energy density usually causes severe structural instability at the deeply delithiated state, resulting in capacity fade and limited lifespan. Herein, we present a series of zinc, yttrium and terbium modified LiCoO2 through solid-state reaction to tackle this long-term issue of structure destruction cycling at high voltages. Compared with the mediocre electrochemical performance of LiCoO2 doped with single elements of Zn, Y and Tb, respectively, the dual-doped LiCoO2 exhibits better structural stability and capacity retention at high voltages. Furthermore, the prepared Zn–Y–Tb ternary-doped LiCoO2 exhibits excellent electrochemical capability with a discharge capacity of 185mAh/g after 100 cycles and capacity retention of 98% at 4.55 V. These multiple dopants synergistically maintain structural integrity after 300 cycles and effectively promote the cycle stability of lithium cobalt oxide cathode material at high voltages.