Influence of Y3+ doping on structure and electrochemical property of the LiMn2O4

The Li1.02YxMn2−xO4 (x = 0, 0.005, 0.01, 0.02, 0.04, 0.1, respectively) were prepared by solid-state reaction method with raw materials of Li2CO3, electrolytic MnO2 and Y2O3. The influence of the Y3+ doping on the spinel LiMn2O4 were systemically investigated by means of X-ray diffraction (XRD), cyclic voltammetry (CV) and AC impedance, and so on. The results show that when x ≤ 0.02, Li1.02YxMn2−xO4 has well-developed crystallite, or there is other phase Y2O3. Cyclic voltammogram testing shows that a small amount of Y3+ doping has no influence on the Li+ intercalation–deintercalation process, but as increased the amount of Y3+ doping, the two-step process of Li+ intercalation–deintercalation transforms to one-step. Simultaneity, Y3+ doping decreases the interacting force among Li+ and Li+, and then availably avoids the energy level splitting. The initial discharge capacity of Li1.02Y0.01Mn1.99O4 is 124.6 mAh g−1. Its capacity and maintaining ratio after 100 cycles are 112.1 mAh g−1 and 90.0%, respectively. It explains that Y3+ doping effectively restricts the Jahn–Teller effect and stabilizes the crystal structure. In addition, the conductivity of the samples is clearly improved due to Y3+ doping.