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- Luo, Zhihui, et al.
(author)
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Revealing the Charge Storage Mechanism of Nickel Oxide Electrochromic Supercapacitors
- 2020
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In: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 12:35, s. 39098-39107
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Journal article (peer-reviewed)abstract
- Nickel oxide (NiO) is considered one of the most promising positive anode materials for electrochromic supercapacitors. Nevertheless, a detailed mechanism of the electrochromic and energy storage process has yet to be unraveled. In this research, the charge storage mechanism of a NiO electrochromic electrode was investigated by combining the in-depth experimental and theoretical analyses. Experimentally, a kinetic analysis of the Li-ion behavior based on the cyclic voltammetry curves reveals the major contribution of surface capacitance versus total capacity, providing fast reaction kinetics and a highly reversible electrochromic performance. Theoretically, our model uncovers that Li ions prefer to adsorb at fcc sites on the NiO(1 1 1) surface, then diffuse horizontally over the plane, and finally migrate in the bulk. More significantly, the calculated theoretical surface capacity (106 mA h g(-1)) accounts for about 77.4% of the total experimental capacity (137 mA h g(-1)), indicating that the surface storage process dominates the whole charge storage, which is in accordance with the experimental results. This work provides a fundamental understanding of transition-metal oxides for application in electrochromic supercapacitors and can also promote the exploration of novel electrode materials for high-performance electrochromic supercapacitors.
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