One-pot synthesis of porous nickel cobalt sulphides: tuning the composition for superior pseudocapacitance. Issue 1 (19th November 2014)

• Record Type: Journal Article
• Authors: Chen, Haichao; Jiang, Jianjun; Zhao, Yuandong; Zhang, Li; Guo, Danqing; Xia, Dandan
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 1(2015)
• Page Start: 428
• Page End: 437
• Publication Date: 2014-11-19
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c4ta04420g
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Superior pseudocapacitance with high specific capacitance, excellent rate capability and improved cycling stability has been attained by tuning the Ni and Co content of Ni–Co sulphides. Abstract : Nickel cobalt sulphides with different stoichiometric nickel and cobalt contents have been synthesized and used as pseudocapacitive materials for supercapacitors. The as-employed polyol method is robust enough to use a one-pot synthesis of nickel cobalt sulphides with similar porous morphology and crystal structure at different nickel and cobalt ratios. The electrochemical performance of the nickel cobalt sulphides can be easily tuned by the varying the Ni and Co content. Owing to the combined contributions from both Ni and Co ions, the bimetallic Ni–Co sulphides show a superior pseudocapacitance compared to monometallic Co and Ni sulphides in terms of high specific capacitance, excellent rate capability and long cycle stability. In particular, the Ni1.5 Co1.5 S4 sample shows the highest specific capacitance of 1093 F g −1 at 1 A g −1, superior rate capability of 69% capacitance retention after a 50-fold increase in current densities, and longer cycle stability with increased specific capacitance of 108% of capacitance retention after 2000 cycles. In addition, the Ni1.5 Co1.5 S4 was also used to assemble an asymmetric supercapacitor with reduced graphene oxide and attains excellent capacitive performance with high specific capacitance (113 F g −1 at 1 A g −1 ), high energy density (37.6 W h kg −1 at 775 W kg −1 ) and high power density (23.25 kW kg −1 at 17.7 W h kg −1 ).