Cycling behavior of ZnO coated LiMn2O4 cathode material which overcomig Mn dissolution in the 4 V region

초록

In view of the economic and environmental advantage, spinel LiMn2O4 has been demonstrated to be the most promising positive electrode material for lithium-ion batteries because they are cheaper, less toxic, and easier to prepare than their alternatives (LiCoO2 and LiNiO2). An important problem prohibiting them from wider use as a cathode for lithium-ion batteries is structual instability from acidic HF attack on the spinel particles at 4 V region. Specially, this problem is extremely accelerated at elevated temperatures. Dissolution of Mn which may accompany structual changes occurs in acidic non-aqueous electrolyte due to instability of the lithiated and delithiated Li-Mn-O phases. In this study, we examined the role of ZnO-coating on the electrochemical performance and structural stability of the LiMn2O4 electrode in the 4 V region at room temparature and 55 . 2 wt% ZnO-coated LiMn2O4 electrode shows excellent capacity retention not only in room temparature but also in high temparature. LiMn2O4 electrode coated with 2wt% ZnO delivers an initial discharge capacity of 125 mAh g-1 without any capacity loss even after 50 cycles at room temparature. Also, 2 wt% ZnO-coated LiMn2O4 electrode at 55 lost only 6% of the initial capacity after 50 cycles, while that of the uncoated electrode shows a 43% loss.