Nitrogen-Doped Graphene-Wrapped Mn₃O₄ Nanoparticles As High-Performance Anode Materials for Lithium Ion Batteries

Abstract

Lithium ion battery (LIB) is one of the most important power sources due to its high energy density [1]. To meet the increasing demands associated with the use of LIB in hybrid electric vehicles, many researches are focused on improving their electrochemical properties in term of materials. Graphite is commonly used as an anode material in commercial LIB. However, as it deliver a low specific capacity, its application in LIB is limited Graphene has awakened a tremendous interest due to its very large surface area (~2600 m 2 g -1 ), excellent electronic conductivity and stability. These properties allow graphene a promising electrode material for LIB. However, graphene exhibits rapid capacity decay during cycling. Nitrogen doping of carbon materials has been studied as an effective way to solve the limitations and improve the electrochemical properties. Actually, nitrogen doping of graphene allows for enhanced interaction with lithium ions and the formation of a greater number of active sites through modulation of the band structure of graphene [2]. However, very few studies have been reported on the use of nitrogen-doped graphene/Mn 3 O 4 composite as the LIB anode material. In this study, we have developed a simple hydrothermal method for the well-deposition of Mn 3 O 4 nanoparticles onto nitrogen-doped graphene. Hydrazine plays an important role in the formation of such nanocomposites since it can act as both a nitrogen source and a reducing agent. In the SEM and TEM images, we have confirmed that highly crystalline Mn 3 O 4 nanoparticles are well-dispersed on the N-doped graphene. The Mn 3 O 4 /N-doped grapheme nanocomposites show excellent electrochemical performance, including outstanding cycling stability, high reversible specific capacity and improved rate capability. The enhancement in the electrochemical properties of the material can be attributed to N-doped graphene, which acts as both a conductive substrate and a volume buffer layer, and also nitrogen doping allows for the fast electron moving and ion transfer by decreasing the energy barrier. Reference [1] M. Winter, R.J. Brodd, Chem . Rev ., 104 ,4245 (2004). [2] H.B. Wang, C.J. Zhang, Z.H. Liu, L. Wang, P.X. Han, H.X. Xu, K.J. Zhang, S.M. Dong, J.H. Yao, G.L. Cui, J . Mater . Chem . 21 , 5430 (2011). Acknowledgement This work was supported by the Center for Integrated Smart Sensors funded by the Ministry of Science, ICT & Future Planningas Global Frontier Project (CISS-2012M3A6A6054193) and partial support from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (no. 2013-053595)