Interfacial Modification of High-Voltage LiCoO2 Materials via Ti/Mg Doping Strategy for Inhibiting Harmful Phase Transition Effect

Abstract

Developing high voltage lithium cobalt oxide (LiCoO₂, LCO) is crucial for attaining the enhanced capacity and energy density of lithium-ion batteries. However, severe interface and structural instability lead to rapid degradation of LCO under the condition of high voltage. Herein, a successful strategy for modifying the interface of LCO is developed using a one-step high temperature process. By coating LCO with Li₃TiMg(PO₄)₃ (LTMP), the obtained phosphate can stabilize the surface crystal structure and boost the mechanical stability of LCO. The high temperature process enables the successful doping of Ti/Mg into the LCO lattice, effectively inhibiting the harmful phase transition effect across various voltage ranges. Compared to commercial LCO and the reported studies, the modified LCO@LTMP performs outstanding electrochemical performance. It delivers an initial discharge specific capacity of 216.4 mAh·g⁻¹ at 0.1 C and 189.98 mAh·g⁻¹ at 1 C. After 250 cycles at 1 C, it preserves 87.46% of its initial capacity, manifesting excellent cycling stability. Moreover, it provides a discharge specific capacity of 115.9 mAh·g⁻¹ at 5 C, demonstrating outstanding rate performance. This work holds great potential for practical applications and offers valuable guidance for developing other high performance cathode materials in rechargeable batteries.