Vanadium trioxide (V2O3) is a promising anode materials for lithium ion batteries, considering that the electrical resistance of bulk V2O3 (10 Ω at 150–350 K) is lower than other transition metal oxides and it possesses a high theoretical capacity (1073 mAh g-1). However, it suffer from poor cycling stability and low rate performance. To improve these we synthesized a composite of vanadium oxide and vanadium oxynitride (V2O3/VOxNy) via a hydrothermal method and a nitridation process. Vanadium oxynitride has a cubic, rock salt structure, which is the same as those of VN and VO. We expect it can improve the V2O3 electrochemical performance due to its low electrical resistivity and high theoretical capacity (1236 mAh g-1). Vanadium pentoxide (V2O5) nanowires were simply synthesized by a hydrothermal method and compressed into free-standing sheets. To improve the cycling performance, we added Super P® to the V2O5 nanowire sheets. They were transformed into vanadium oxide and vanadium oxynitride carbon composite (V2O3/VOxNy-C) sheets by a nitridation process. They were heated at 300 - 700 oC under flowing NH3(g). Different vanadium oxide and vanadium oxynitride ratios were prepared by controlling the nitridation temperature. They were directly used as the binder free anode electrodes for lithium ion batteries. As a result, a V2O3/VOxNy-C//Li half cell delivered 276 mAh g-1 for 50 cycles at a current density of 80 mA g-1. This indicates a good electrochemical performance from the composite material. Most important of all, under the optimized mass loadings, full cells were assembled by using the V2O3/VOxNy-C composites and commercial LiCoO2, served as the anode and the cathode, respectively. The electrolyte was LiPF6 (1M) in a solution of ethylene carbonate (EC)/diethyl carbonate (DMC) (1:1 in volume). The full cell delivered a capacity of 78 mAh g-1 for 50 cycles at a current density of 0.15C (1C=274 mA g-1), which shows a good electrochemical performance. We expect further improvements will enhance the performance significantly.

Vanadium oxide and vanadium oxynitride composite as electrode materials for lithium ion batteries

253rd National Meeting (2017)

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