BiFeO-coated spinel LiNiMnO with improved electrochemical performance as cathode materials for lithium-ion batteries

Spinel LiNiMnO cathode material is a promising candidate for next-generation rechargeable lithium-ion batteries. In this work, BiFeO-coated LiNiMnO materials were prepared via a wet chemical method and the structure, morphology, and electrochemical performance of the materials were studied. The coating of BiFeO has no significant impact on the crystal structure of LiNiMnO. All BiFeO-coated LiNiMnO materials exhibit cubic spinel structure with space group of 3. Thin BiFeO layers were successfully coated on the surface of LiNiMnO particles. The coating of 1.0 wt% BiFeO on the surface of LiNiMnO exhibits a considerable enhancement in specific capacity, cyclic stability, and rate performance. The initial discharge capacity of 118.5 mAh g is obtained for 1.0 wt% BiFeO-coated LiNiMnO with very high capacity retention of 89.11% at 0.1 C after 100 cycles. Meanwhile, 1.0 wt% BiFeO-coated LiNiMnO electrode shows excellent rate performance with discharge capacities of 117.5, 110.2, 85.8, and 74.8 mAh g at 1, 2, 5, and 10 C, respectively, which is higher than that of LiNiMnO (97.3, 90, 77.5, and 60.9 mAh g, respectively). The surface coating of BiFeO effectively decreases charge transfer resistance and inhibits side reactions between active materials and electrolyte and thus induces the improved electrochemical performance of LiNiMnO materials.