In situ hydrothermal synthesis of Mn₃O₄ nanoparticles on nitrogen-doped graphene as high-performance anode materials for lithium ion batteries

Developing new electrode materials with high specific capacity for excellent lithium ion storage properties is very desirable. In this paper, we introduce a simple hydrothermal method for the growth of Mn₃O ₄ nanoparticles onto nitrogen-doped graphene (N-doped graphene) for high-performance lithium ion battery (LIB) anodes. Hydrazine plays a fundamental role in the formation of such nanostructures as it can act both as a reducing agent and as a nitrogen source. In the synthesized composite, highly crystalline Mn₃O₄ nanoparticles with average sizes of 20-50 nm are homogeneously dispersed on both sides of the N-doped graphene. The nitrogen content in the doped graphene is confirmed by elemental analyzer, and 2 wt% of the sample is found to be composed of nitrogen element. The as-prepared Mn ₃O₄/N-doped graphene composites exhibit remarkable electrochemical performance, including high reversible specific capacity, outstanding cycling stability, and excellent rate capability (approximately 400 mA h g^-1 at 2.0 A g^-1) when used as the anode material for LIBs. The improvement in the electrochemical properties of the material can be attributed to graphene, which acts as both an electron conductor and a volume buffer layer, and nitrogen doping allows for fast electron and ion transfer by decreasing the energy barrier. This type of metal oxide/N-doped graphene composites can be promising candidates for high-performance anode materials for LIBs.