Phase transition regulation and Cd-O/Cd-F compounds multi-effect modification synergistically act on LiNi0.5Mn1.5O4 cathode

Abstract

LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for lithium-ion batteries due to its high discharge voltage, low cost, environmental friendliness, and high energy density. To enhance the electrochemical performance of LNMO, Cd is innovatively employed as a modifying agent. Structural and morphological characterizations confirm that CdO is successfully wrapped on the surface of LNMO. Further physical, chemical, and electrochemical detections verify the phase transition of LNMO. The CdO-coated samples show excellent cyclability and rate performance. The CdO-coated LNMO (Cd 0.4 wt.%) exhibits a discharge capacity of 133.3 mAh g−1 with a retention rate of 95.2% after 300 cycles at 1-C rate (3.5–4.8 V), while that of the pristine is only 89.4%. Even at 10-C rates, the CdO-coated LNMO has an initial discharge capacity of 120.0 mAh g−1 with a retention rate of 92.3% after 300 cycles at the same voltage limit. Specifically, at the first of cycling, the newly formed Cd-F compounds and CdO layer could suppress the side reactions and reduce the formation of surface film. Finally, the process of kinetics is improved.