Preparation of Porous Nickel-Cobalt Layered Double Hydroxide Arrays and Its Capacitance Performance
In this paper,nickel-cobalt layered double hydroxides(NiCo-LDHs)were synthe-sized on nickel foam(NF)by one-step hydrothermal method.The effects the molar ratio Ni and CO on the crystal structure,morphology and capacitive properties were studied.When n(Ni)∶n(Co)=2∶2,ordered and dense porous Ni2Co2-LDHs nanoneedle arrays with high capacitance and high cycle stability were obtained.The specific capacitance is 2 381 F·g-1 at 1 A·g-1,the capacitance retention rate is 57.1%at 10 A·g-1 and 60%after 4 500 charge discharge cycles,respectively.Finally,an asymmetric supercapacitor was constructed with Ni2Co2-LDH@NF as the positive electrode material and commercial activated carbon as the negative electrode material.The specific capacitance is 211.4 F·g-1 at 1 A·g-1,the capacitance retention rate is 90%after 5 000 charge-discharge cycles at 5 A·g-1.It has an energy density of 73.1 kW·kg-1 at a power density of 11.6 kW·kg-1.
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