Proton solvent-controllable synthesis of manganese oxalate anode material for lithium-ion batteries

Manganese oxalates with different structures and morphologies were prepared by the precipitation method in a mixture of dimethyl sulfoxide (DMSO) and proton solvents. The proton solvents play a key role in determining the structures and morphologies of manganese oxalate. Monoclinic MnC₂O₄·2H₂O microrods are prepared in H₂O-DMSO, while MnC₂O₄·H₂O nanorods and nanosheets with low crystallinity are synthesized in ethylene glycol-DMSO and ethanol-DMSO, respectively. The corresponding dehydrated products are mesoporous MnC₂O₄ microrods, nanorods, and nanosheets, respectively. When used as anode material for Li-ion batteries, mesoporous MnC₂O₄ microrods, nanorods, and nanosheets deliver a capacity of 800, 838, and 548 mA h g^-1 after 120 cycles at 8C, respectively. Even when charged/discharged at 20C, mesoporous MnC₂O₄ nanorods still provide a reversible capacity of 647 mA h g^-1 after 600 cycles, exhibiting better rater performance and cycling stability. The electrochemical performance is greatly influenced by the synergistic effect of surface area, morphology, and size. Therefore, the mesoporous MnC₂O₄ nanorods are a promising anode material for Li-ion batteries due to their good cycle stability and rate performance.