Supercritical ethanol deposition of Ni(OH)2 nanosheets on carbon cloth for flexible solid-state asymmetric supercapacitor electrode

Abstract

Ni(OH)2 nanosheets (NSs) were grown onto an electrochemically activated carbon cloth (ECC) with a self-supported microstructure by using efficient ethanol assisted supercritical deposition method. Benefited from the structural features of the well-developed porous architecture with effective channels for electrolyte ions diffusion and accessible redox sites, the nano-heterostructure brings a high utilization of electroactive material and thereby good electrochemical performance. The specific capacity of 918 mC cm−2 at 2 mA cm−2 with good rate performance (68.4 % retention at 20 mA cm−2) was achieved for the obtained Ni(OH)2 NSs/ECC flexible electrode. The assembled flexible solid-state device with a 1.8 V operating potential displays an energy density of 8.3 mW h cm-3 at 20 mW cm-3. Additionally, the as-fabricated device reveals cyclic stability with 87 % capacity retention (10,000 cycles at 50 mA cm−2). These results show the importance of supercritical fluid deposition as a potential method for supercapacitors electrode.