Zn-Co phosphide porous nanosheets derived from metal-organic-frameworks as battery-type positive electrodes for high-performance alkaline supercapacitors. (20th December 2020)

• Record Type: Journal Article
• Authors: Chu, Wenjing; Hou, Yongdan; Liu, Juyin; Bai, Xue; Gao, Yan fang; Cao, Zhenzhu
• Is Part Of: Electrochimica acta. Volume 364(2020)
• Publication Date: 2020-12-20
• Subjects: Zn-Co phosphide nanosheets -- Battery-type material -- High energy density -- DFT calculation -- Alkaline supercapacitors; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2020.137063
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Zn0.33 Co0.67 P displays a maximum specific capacitance of 2115.5 F g -1 at 1 A g -1 . Zn-Co phosphide porous nanosheets battery-type advanced material derived from Metal-organic-frameworks is synthesized. The cycling performance of Zn0.33 Co0.67 P electrode has an excellent capacitance retention of 80.4% after 7000 cycles at current density of 10 A g -1 . Zn0.33 Co0.67 P//Bi2 O3 alkaline SC delivers a high energy density of 83.05 Wh kg -1 at 775.02 W kg -1 . Abstract: Excellent electrode materials are often desired to improve the overall performance of supercapacitors and conversion components, especially electrode materials synthesized by anion replacement to achieve high electrochemical performance. Herein, a zinc–cobalt phosphide electrode material with excellent electrical conductivity is synthesized through a metal–organic framework (MOF)-derived method, followed by phosphating in a tube furnace. As a result, an exchange of phosphorus ions and oxygen ions occurs, yielding a high specific capacitance of 2115.5 F g -1 at 1 A g -1, as well as a superior rate capacity of 1086.5 F g -1 at 50 A g -1 . After 7000 cycle tests, 80.3% of the initial specific capacitance is maintained. Phosphorus substitution leads to a narrowed band gap, resulting in outstanding electrical conductivity, as confirmed through density functional theory (DFT) calculations. Subsequently, the self-assembled Zn0.33 Co0.67 P//Bi2 O3 alkaline supercapacitor exhibits a high energy density of 83.05 Wh kg -1 (248.9 F g -1 at 1 A g -1 ) at a power density of 775.02 W kg -1 . Meanwhile, a capacitance retention of 84.6% after 8000 cycles at a current density of 5 A g -1 is obtained. The outstanding performances of the electrode material in terms of electrical conductivity and electrochemical activity provide a new method for the design of high energy density alkaline supercapacitors (SCs). Graphical abstract: Image, graphical abstract