Enhancement of LiMn2O4 Cathode Material Stability by LiB3O5 Coating and Synchronized B Doping

Spinel manganese lithium oxide (LMO) has garnered considerable attention as a promising cathode material for lithium-ion batteries, because of its low cost, superior safety, and cycling stability. However, its rapid capacity fading, particularly at increased temperatures, poses a challenge to its widespread application. To enhance the cycling stability of LMO, we employ a straightforward method to coat LiB3O5, a material characterized by chemical and electrochemical stability, an appropriate electrochemical window, and excellent lithium-ion conductivity, onto the surface of LMO particles. Among all coated samples, the one with 2% LiB3O5 (2% LBO@LMO) demonstrates the most remarkable performance. After 300 cycles at 25 °C and a rate of 1C, its capacity retention was 88.55%, compared to 58.47% for uncoated LMO. At 55 °C and a rate of 1C, the 2% LBO@LMO sample maintains a capacity retention of 77.38% after 100 cycles while the uncoated LMO retains only 58.37%. Further investigation into the mechanism underlying the enhanced cycling performance reveals that the LiB3O5 coating simultaneously induces surface boron doping, altering the valence state distribution of Mn elements. Additionally, LiB3O5 coating mitigates particle cracking, prevents Mn dissolution, and increases the lithium-ion conductivity rate. This study paves new avenues for the utilization of lithium borate materials and promotes the broader adoption of manganese lithium oxide cathode materials.