(1 The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China) (2 Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, Wuhan 430074, China)
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DOI:
10.7502/j.issn.1674-3962.2016.07.10
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Abstract:
With growing concerns over fossil energy and ever-increasing environmental pollution, there is a strong and growing demand for the development of efficient energy-storage systems for applications in portable electric devices, smart grids and electric vehicles (EVs). Supercapacitor (SC), an emerging energy storage device that bridges the gap between conventional capacitors and rechargeable batteries, has attracted increasing attentions due to its large power density, long-term operation stability as well as high safety. Electrode materials are the key components of SCs, largely determining the device performance. Transitional metal nitrides (MxN，M=Ti, V, Mo, Nb, W) are promising electrochemical electrode materials for SCs due to high conductivity and large specific capacitance. Compared to carbon electrodes such as carbon nanotube, graphene and active carbon, metal nitrides exhibit higher specific capacitance, especially much higher volumetric capacitance. Additionally, because of high conductivity like metal, transitional metal nitrides exhibit super rate performance and higher power density at high current density compared to metal oxide electrodes such as manganese oxides and nickel oxides. This review summarizes the most recent progress in fabrication, morphology, capacitive properties and energy storage mechanism of several typical transitional metal nitride nanostructures. Flexible and bendable electrodes consisting of three dimensional intertwined metal nitride nanowires were fabricated by a simple vacuum filtration method and their outstanding electrochemical properties were reported. The flexible all-solid-state supercapacitor devices with high-energy storage properties were produced based on flexible electrodes of transitional metal nitride nanowires together with the gel-like electrolyte. Finally, the perspective of transitional metal nitrides for better energy storage devices is also discussed.