Turning commercial MnO2 (≥85 wt%) into high-crystallized K+-doped LiMn2O4 cathode with superior structural stability by a low-temperature molten salt method

Abstract

The obtainment of low-cost, easily prepared and high-powered LiMn2O4 is the key to achieve its wide application in various electronic devices. In this work, a mild and easily scaled molten salt method (KCl@LiCl) is utilized to convert commercial MnO2 to the high-performance LiMn2O4. At the same reaction temperature, the molten salt method leads to the formation of K+-doped LiMn2O4 with higher crystallinity compared to the conventional solid state method, which contributes to the improved inner charge transfer. The Li3PO4 protective layer is coated on the surface of K+-doped LiMn2O4 to elevate the interfacial stability and the Li+ transfer on interface. Thus, the optimized electrode shows a higher specific discharge capacity (103/60 mAh g−1 at 0.02/2 A g−1) and a longer cyclic life (80 mAh g−1 after 500 cycles at 0.5 A g−1) compared to those of LiMn2O4 by solid state method (49/2 mAh g−1 at 0.02/2 A g−1 and 20 mAh g−1 after 500 cycles at 0.5 A g−1).