BiFeO3-coated spinel LiNi0.5Mn1.5O4 with improved electrochemical performance as cathode materials for lithium-ion batteries

摘要

Spinel LiNi0.5Mn1.5O4 cathode material is a promising candidate for next-generation rechargeable lithium-ion batteries. In this work, BiFeO3-coated LiNi0.5Mn1.5O4 materials were prepared via a wet chemical method and the structure, morphology, and electrochemical performance of the materials were studied. The coating of BiFeO3 has no significant impact on the crystal structure of LiNi0.5Mn1.5O4. All BiFeO3-coated LiNi0.5Mn1.5O4 materials exhibit cubic spinel structure with space group of Fd3m. Thin BiFeO3 layers were successfully coated on the surface of LiNi0.5Mn1.5O4 particles. The coating of 1.0 wt% BiFeO3 on the surface of LiNi0.5Mn1.5O4 exhibits a considerable enhancement in specific capacity, cyclic stability, and rate performance. The initial discharge capacity of 118.5 mAh g(-1) is obtained for 1.0 wt% BiFeO3-coated LiNi0.5Mn1.5O4 with very high capacity retention of 89.11% at 0.1 C after 100 cycles. Meanwhile, 1.0 wt% BiFeO3-coated LiNi0.5Mn1.5O4 electrode shows excellent rate performance with discharge capacities of 117.5, 110.2, 85.8, and 74.8 mAh g(-1) at 1, 2, 5, and 10 C, respectively, which is higher than that of LiNi0.5Mn1.5O4 (97.3, 90, 77.5, and 60.9 mAh g(-1), respectively). The surface coating of BiFeO3 effectively decreases charge transfer resistance and inhibits side reactions between active materials and electrolyte and thus induces the improved electrochemical performance of LiNi0.5Mn1.5O4 materials.