Preparation And Electrochemical Performances Of Ni-Co-Cu Compound Electrode Material

Supercapacitors attract considerable attention due to their high-power-density,fast charging and discharging,and impressive cycle stability.However,their commercialization is severely restricted by their low energy density.Electrode materials are crucial in determining the electrochemical performance of supercapacitors,thus design and develop new electrode materials with high specific capacitance and good cycle stability is especially important for achieving supercapacitor application.Pseudocapacitive materials based on faradic reaction have higher specific capacity.Among various electrode materials,Ni-Co based transition metal carbonate hydroxides show high specific capacitance due to their unique crystal structure and facile insertion and diffusion of electrolyte ions for fast redox reaction.Therefore,Ni-Co based transition metal carbonate hydroxides have been widely applied in the energy storage systems.Herein,urchin-like nickel cobalt copper ternary carbonate hydroxide was successfully synthesized by a one-step hydrothermal method through metal ions doping.Also by adding sulfur source,ternary transition metal sulfide was prepared via a hydrothermal method,and all-solid hybrid supercapacitor was assembled using the obtained ternary transition metal sulfide as the cathode material.The assembled device shows good electrochemical performance.The main conclusions are as follows:1.Urchin-like Ni_0.3Co_0.6Cu_0.1（CO₃）_0.5（OH）was synthesized by one-step hydrothermal method through tuning the mass ratio of reactants,hydrothermal reaction temperature and time.The electrode material has a large specific surface area due to their structural characteristics,and provides abundant active sites,which accelerates the faradic energy storage process.The electrochemical performance of Ni_0.3Co_0.6Cu_0.1（CO₃）_0.5（OH）was tested in a standard three-electrode system with 1M KOH as electrolyte.Ni_0.3Co_0.6Cu_0.1（CO₃）_0.5（OH）electrode material delivers a high specific capacitance of1479.7 F g^-1 at 1 A g^-1,high rate performance(capacity retention of 72.6%from 1 A g^-1to 20 A g^-1),and outstanding long-term cycle stability(83.4%capacitance retention after10000 cycles at 10 A g^-1).2.Flower-like Ni Co_1.43Cu_0.57S₄ was synthesized via one step hydrothermal method.Under optimum preparation parameters（hydrothermal temperature/time:120℃/10 h）,Ni Co_1.43Cu_0.57S₄ electrode material achieves a specific capacitance of 912.5 F g^-1 at 1 A g^-1,and realizes 71.9%capacity retention after 10000 cycles at a high current density of10 A g^-1,indicating good cycling stability.3.All-solid supercapacitor was assembled with Ni Co_1.43Cu_0.57S₄ as the positive material,commercial active carbon（AC）as the negative material,and polybenzimidazole（PBI）as the separator.The voltage window of the supercapacitor device reaches up to 1.6V,and its energy density is 35.5 Wh kg^-1at a power density of 400.4 W kg^-1.After 5000cycles at 10 A g^-1,such assembled device retains 71.3%capacity,showing good cycle stability.