Turning commercial MnO₂ (≥85 wt%) into high-crystallized K⁺-doped LiMn₂O₄ cathode with superior structural stability...

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).