One-pot solvothermal synthesis of Co1−xMnxC2O4 and their application as anode materials for lithium-ion batteries

• Mixed metal oxalates are synthesized by solvothermal method for the first time.
• We control morphologies by varying solvent mixtures and transition metal types.
• Li/Co0.52Mn0.48C2O4 is the best capacity and rate-performing cell in this study.
• The positive synergistic effect is attributed to optimal Co:Mn mole ratio.
• Properties of Co give high capacity values while Mn give good cycling stability.

A facile one-pot solvothermal route has been developed to synthesize phase pure MxC2O4⋅2H2O (M = Mn, Co; 0 < x ⩽ 1) microstructures without employing any hard/soft template and their electrochemical performance in lithium-ion batteries has been systematically investigated. Morphology, microstructure and composition of the synthesized materials are characterized by field emission-scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. Anhydrous micron-sized MnC2O4 and CoC2O4 exhibits specific reversible discharge capacity of ∼800 and 950 mA h g−1 respectively, at 1 C-rate. MnC2O4 exhibited good cycling stability while CoC2O4 showed severe capacity fading phenomenon after 40 cycles, thereafter attaining 400–600 mA h g−1 for all C-rates. Interestingly, mixed solid solution having Co0.52Mn0.48C2O4 composition improved the specific reversible discharge capacity to a stable value of ∼1000 mA h g−1 (1 C-rate), which is one of the highest reported values for such oxalates. The cycling stability of this mixed metal oxalate is remarkably better than its individual constituents at most C-rates. The Mn2+ substitution into CoC2O4 lattice has led to the synergistic modification of the electrochemical performances, thus making it a promising anode candidate for future LIBs.

MnC2O4 exhibited good cycling stability while CoC2O4 showed severe capacity fading phenomenon after 40 cycles. Notably, mixed solid solution having Co0.52Mn0.48C2O4 composition improved the specific reversible discharge capacity to a stable value of ∼1000 mA h g−1 (1 C-rate).Figure optionsDownload as PowerPoint slide