Spinel LiNi0.5Mn1.5O4 cathode materials with different lithium excess amount (0, 2%, 6%, 10%) were synthesized by a facile solid-state method. The effect of lithium excess amount on the microstructure, morphology, and electrochemical properties of LiNi0.5Mn1.5O4 materials was systematically investigated. The results show that the lithium excess amount does not change the particle morphology and size obviously; thus, the electrochemical properties of LiNi0.5Mn1.5O4 are mainly determined by structural characteristics. With the increase of lithium excess amount, the cation disordering degree (Mn3+ content) and phase purity first increase and then decrease, while the cation mixing extent has the opposite trend. Among them, the LiNi0.5Mn1.5O4 material with 6% lithium excess amount exhibits higher disordering degree and lower impurity content and cation mixing extent, thus leading to the optimum electrochemical properties, with discharge capacities of 125.0, 126.1, 124.2, and 118.9 mAh/g at 0.2-, 1-, 5-, and 10-C rates and capacity retention rate of 96.49% after 100 cycles at 1-C rate.
Lithium-ion battery Cathode material LiNi0.5Mn1.5O4Lithium excess amount Electrochemical performance
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The authors are grateful to the Natural Science Foundation of Hebei Province (Grant number E2015202356), Key R&D Plan Self-raised Project of Hebei Province (Grant number 16214406), and Technology Innovation Foundation Project for Outstanding Youth of Hebei University of Technology (Grant number 2013009) for the financial support of this work.
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