Insights in utilizing NiCo2O4/Co3O4 nanowires as anode material in Li-ion batteries

Tomar, Anubha; Adhitama, Egy; Winter, Martin; Placke, Tobias; Rai, Alok Kumar

Abstract

In this study, a facile and cost-effective hydrothermal approach is employed to synthesize a mesoporous NiCo2O4/Co3O4 nanocomposite with nanowire morphology by using polyvinyl pyrrolidone as structure-directing agent. The obtained iCo2O4/Co3O4 nanocomposite shows better electrochemical performance than pure NiCo2O4 due to mainly two reasons: (i) a strong synergistic effect between NiCo2O4 and Co3O4, which enhances the Li+ diffusion rate as well as lower the charge-transfer resistance, and (ii) the involvement of Co3O4 to contribute in the total capacity due to its high electrochemical activity. However, the performance of a NiCo2O4/Co3O4 nanocomposite electrode starts degrading after 400 cycles while pure NiCo2O4 maintains steady performance. Since the NiCo2O4/Co3O4 nanocomposite sample shows high porosity, it is believed that the obtained nanowire morphology cannot tolerate volume variations, which are generally triggered off during repeated Li+ (de-)insertion at long-term cycling. Therefore, the obtained results bring new insights in terms that there is a sweet spot between Li+ diffusion and high porosity in utilizing Co3O4 within a nanocomposite. This study is of guidance to shed the light on the research of ternary transition metal oxide nanocomposite materials for lithium ion batteries.

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