Multi-element synergistic doping enhances high-voltage performance of LiCoO2 via stabilizing internal and surface structures

Abstract

With the escalating commercialization of 5 G technology and the constant emergence of novel electronic devices, the demand for energy density of LiCoO2 cathode material has been on a consistent rise. Boosting the upper cut-off voltage is an essential approach for enhancing the energy density. While the high-voltage environment facilitates adverse side reactions like irreversible phase transition and electrolyte degradation, thereby accelerating battery capacity degradation. Herein, a straightforward and efficient high-temperature solid-phase strategy is utilized and the elements Ba, Mg, Ga, and Ti are selected for trace doping. Our findings reveal positive synergistic effects among these elements. Mg and Ga significantly suppress the arising of oxygen ligand holes. The distinct distribution of Mg and Ba balances and improves the electronic conductivity inside the elementary particles. Additionally, a triple control system of Ba, Mg, and Ga highlights the important role of Ti. Advanced characterization methods confirm that this approach reduces the particle radius and enhances rapid charging and discharging capabilities of the cathode material. What's more, it effectively suppresses harmful phase transitions and side reactions, maintaining the structure stability. Within the range of 3–4.6 V, the discharge specific capacity reaches 188 mAh/g after 100 cycles, with a capacity retention of 86 %. Furthermore, it demonstrates outstanding rate performance, achieving a specific capacity of 104 mAh/g at 10 C. This improved electrochemical performance underscores the benefits of the synergistic strategy utilizing Ba, Mg, Ga, and Ti, providing a novel approach for developing high-performance LiCoO2 materials.