Synthesis of high-performance MnOx/carbon composite as lithium-ion battery anode by a facile co-precipitation method: Effects of oxygen stoichiometry and carbon morphology

• MnOx/C composite powders are prepared by co-precipitation followed by calcination.
• Two C materials, including carbon black (CB) and graphitic flake (GF), are used.
• Effects of temperature and C on performance as Li ion battery anode are studied.
• GF benefits oxide reduction and oxide/C contact, enhancing capacity and cycle life.
• MnO/GF shows capacity of 580 mAh g−1-(oxide + C) without fading after 150 cycles.

Manganese oxide/carbon (MnOx/C) composite powders showing high performance as lithium-ion battery anode are synthesized by a facile co-precipitation process followed by thermal calcination between 400 °C and 700 °C in N2, where the as-deposited MnO2 is reduced progressively to Mn3O4 and then to MnO. The role of conductive additive is investigated by adopting two carbon (C) materials of different dimensionalities, including carbon black (CB) nanoparticles and micron-sized graphitic flakes (GFs). For MnOx/CB composite, the cycling stability is remarkably enhanced with increasing calcination temperature, and this is due to increasing content of MnO, which exhibits superior redox reversibility than the oxides having higher Mn valences. Attempt to achieve single-phase MnO at higher temperature (700 °C), nevertheless, leads to deteriorated cycle performance because of the formation of large oxide particles having poor contact with CB. The use of the two-dimensional GFs creates the “balls-on-plate” oxide-C configuration. This configuration facilitates MnO formation at lower temperature and simultaneously enables retention of good oxide-C contact, leading to significantly enhanced cycling stability and rate performance. The MnOx/GF composites obtained by calcination at 500–600 °C show specific capacities of 550–600 mAh g−1-(oxide + C) with no capacity fading after 150 cycles.