Hydrothermally Synthesized CoMn₂O₄/Graphite Composite as a High-Capacity Anode for Lithium-Ion Batteries

Abstract

The increasing demand for high-energy-density lithium-ion batteries (LIBs) drives the development of anode materials with capacities exceeding that of graphite (372 mAh g⁻¹). CoMn₂O₄, with a high theoretical capacity (921 mAh g⁻¹), is a promising candidate but suffers from low conductivity and severe volume expansion. In this work, a CoMn₂O₄/graphite (CMO/g) composite is developed to address these limitations through a synergistic effect. CoMn₂O₄ is synthesized via a hydrothermal method followed by calcination, and the sample treated at 700 °C exhibits the best crystallinity and morphology. Structural characterizations (XRD, FTIR, FESEM-EDX) confirm the successful formation of the composite and uniform distribution of CoMn₂O₄ on graphite. Electrochemical evaluations reveal that CMO/g-3 delivers a high initial discharge capacity of 2503 mAh g⁻¹ and maintains ~1000 mAh g⁻¹ after 100 cycles with nearly 100% coulombic efficiency and low charge-transfer resistance. A full cell assembled with CMO/g-3 and LiFePO₄ provides an initial discharge capacity of 146.5 mAh g⁻¹ at 0.2 A g-1, although capacity fading occurs upon prolonged cycling due to volume expansion effects. Overall, the CoMn₂O₄/graphite composite demonstrates enhanced electrochemical performance and promising potential as a high-capacity anode material for next-generation LIBs.