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.