Preparation of binder-free porous ultrathin Ni(OH)2 nanoleafs using ZnO as pore forming agent displaying both high mass loading and excellent electrochemical energy storage performance

Abstract

Ni(OH)2 has been reported widely as one of the most promising supercapactior electrode materials due to its high specific capacitance, yet which were only based on low mass loading. Thus, it is desirable to promote supercapacitor performance for high mass loading Ni(OH)2 through optimizing microstructure. In this work, we first prepared crossed ultrathin Ni(OH)2/ZnO nanoleafs directly grown on nickel foam via hydrothermal method, and then we produced pores on the nanoleafs by dissolving ZnO in alkaline solution. Definitely, this unique structure design for high mass loading binder-free Ni(OH)2 electrode could benefit the penetration of electrolyte and the transportation of electrons, efficiently improving the supercapacitor performance. The obtained porous Ni(OH)2/NF electrode exhibits a mass specific capacity of 1142Cg−1 based on 10mg active materials, equating to a areal specific capaciy of 11.4Ccm−2, and pleasant cycling stability with retention of 85% of initial capacity after 10000 charge-discharge cycles. The fabricated asymmetric device shows a high energy density of 42 Wh kg−1 (4.73 mWh cm−3) at power density of 105Wkg−1 (17mWcm−3). These results demonstrate the optimized structure makes the high mass loading binder-free Ni(OH) 2/NF electrode could also display excellent supercapacitor performance.