Amorphous cobalt hydroxysulfide nanosheets with regulated electronic structure for high-performance electrochemical energy storage

Abstract

Pseudocapacitors with high power density, long-term durability, as well as reliable safety, play a key role in energy conversion and storage. Designing electrode materials combing the features of high specific capacitance, excellent rate performance, and outstanding mechanical stability is still a challenge. Herein, a facile partial sulfurization strategy has been developed to modulate the electronic structure and crystalline texture of cobalt hydroxide nanosheets (denoted as Co(OH)2) at room temperature. The resultant cobalt hydroxysulfide nanosheet (denoted as CoSOH) electrode with abundant low-valence cobalt species and amorphous structure, exhibits a high specific capacitance of 2110 F g−1 at 1 A g−1 with an excellent capability retention rate of 92.1% at 10 A g−1, which is much larger than that of Co(OH)2 precursor (916 F g−1 at 1 A g−1 and 80% retention at 10 A g−1). Furthermore, the fabricated asymmetric supercapacitor device con structed with CoSOH and active carbon displays a considerable high energy density of 44.9 W h kg−1 at a power density of 400 W kg−1, and exceptional stability after 8000 cycles.