Nickel-based materials for supercapacitors

A clear understanding of energy and environmental problems stimulates exploration of clean and versatile energy sources. The majorities of sustainable energy sources are intermittent and therefore need compatible energy storage technologies. Supercapacitors have stimulated a great scientific interest due to their importance for energy storage. Electrode materials, as the key part of supercapacitors, determine their performance. Nickel oxide/hydroxide, characterized by ultrahigh theoretical capacitance and other intriguing features, has drawn considerable attention. However, its poor rate capability and low conductivity hinder its widespread application. Recently, tremendous efforts have been devoted toward resolving those issues. This review presents a concise compilation of the recent progress in the area of nickel-based materials by categorizing them into several groups based on chemical composition. Important issues associated with the fabrication and properties of these materials as well as with the improvement of their performance are discussed. The underlying reasons for the observed synergistic effects are analyzed and highlighted. Finally, the challenges and possible solutions are briefly presented with some perspectives toward future development of this group of materials.