Nickel and Lanthanum Hydroxide Nanocomposites with Much Improved Electrochemical Performance for Supercapacitors

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• 作者：Kuan-Hung Ho ; Huajun Liu ; Qing Qing Ke ; Lu Mao ; Yating Hu ; Xu Li and John Wang
• 刊名：Journal of the American Ceramic Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：100
• 期：1
• 页码：247-256
• 全文大小：1584K
• ISSN：1551-2916

文摘

By developing a facile low temperature hydrothermal process, we demonstrate the direct growth of nickel and lanthanum hydroxide nanocomposites on Ni-foam substrate. The hydroxide nanocomposites thus derived show much enhanced overall electrochemical capacitance and improved stability of the alpha nickel hydroxide phase in alkaline solution. By adjusting the initial molar ratio between nickel and lanthanum nitrates from 1:0 to 1:2, the electrochemical behavior, such as specific capacitance, shows a dramatic change, while the nickel hydroxide phase evolves from beta nickel hydroxides (1:0) to alpha nickel hydroxide (1:2). Lanthanum hydroxide is not expected to contribute to the pseudocapacitance as it only shows a capacitance of <10 F/g. The specific capacitance is increased from 970 F/g (Ni:La = 1:0) to 1874 F/g (Ni: La = 1:2) at the discharging current of 1 A/g. At high discharging currents (e.g. 10 A/g), the Ni:La = 1:2 sample can retain a capacitance of 1055 F/g. An excellent cycling performance is demonstrated for the Ni:La = 1:2 nanocomposite sample upon 2000 cycles at the discharging current density of 2 A/g, where the stability of alpha nickel hydroxide in the alkaline solution is improved. The low temperature hydrothermal method compares favorably to other previously documented preparation processes, such as chemical coprecipitation and electrochemical deposition, for lanthanum-doped nickel hydroxides, where the specific capacitance is typically less than 1000 F/g (1 A/g).