Preparation And Properties Of Copper Oxide-based Supercapacitor Electrode Materials

Supercapacitors,a novel device between traditional capacitors and rechargeable battery,have broad application prospects in the field of new energy storage due to their advantages of fast charge and discharge speed,long cycle life,high power density,and environmental friendliness.The oxides/hydroxides of transition metal elements play an important role in pseudocapacitor materials,but there are some factors limiting their development,such as low electronic conductivity and poor long-term cycling stability.At present,an effective way to solve the above problems is that constructing a transition metal oxide/hydroxide nanoarray on a conductive current collector.In this dissertation,we constructed pseudocapacitor electrode materials on different conductive current collectors(copper foam,nickel foam,and carbon cloth),and studied their supercapacitor performance in 6 mol L-1 KOH electrolyte.The main research contents and results are as follows:(1)Based on three-dimensional nickel foams,an electrode with hieratical CuO clusters were synthesized via the electroless copper plating and chemical etching processes.The CuO-Ni electrode has both excellent rate performance and excellent cycle stability.The specific areal capacitance of CuO-Ni electrode reaches up to 1.61 F cm-2,and retains 93.6%even after 5000 testing cycles.The asymmetric supercapacitor(ASC)device with CuO-Ni positive electrode and active carbon(AC)negative electrode,demonstrates a remarkable energy density of 43.12 Wh kg-1 even at a high power density of 2.12 kW kg-1.(2)Based on three-dimensional copper foams,core-shell Ni(OH)2@CuO electrodes were synthesized by a facile thermal oxidation and chemical bath deposition method.The electrochemical experiments present that the Ni(OH)2@CuO electrode delivers large areal capacitance(1.625 F cm'2),and brilliant cycling stability(retaining 96.4%after 5000 cycles).In addition,an asymmetric supercapacitor(ASC)device was designed taking Ni(OH)2@CuO electrode and active carbon(AC)as a positive and negative electrode,respectively.The ACS device exhibits a remarkable energy density up to 58.59 Wh kg-1 at a power density of 686.45 W kg-1.(3)Based on carbon cloth,Cu2O/CuO nanosheets were constructed by a simple strategy with electroless copper plating,chemical etching,and thermal dehydration.The composite electrode exhibits high specific capacitance about 1.71 F cm-2.After 5000 testing cycles,the capacitance retention of the electrode material is 85.6%,indicating that the electrode material has excellent cycle performance.The asymmetric supercapacitor device using Cu2O/CuO@Cu-CCs as the positive electrode and activated carbon as the negative electrode,achieves a superior energy density up to 60.26 Wh kg-1 at a power density of 299.73 W kg-1 and an excellent long-term cycling stability(9.65%loss of its initial capacitance after 5,000 cycles).(4)Based on carbon cloth,CuO nano wires were synthesized by a facile thermal oxidation method.Then the Fe2O3@CuO anode and Ni(OH)2@CuO anode were constructed using the hydrothermal method and the chemical bath deposition method,respectively,and assembled high performance asymmetric super capacitor.The results show that the specific capacities of the Fe2O3@CuO and Ni(OH)2@CuO electrodes are 0.772 F cm-2 and 2.282 F cm-2,respectively.In addition,an asymmetric supercapacitor(ASC)device was designed taking Fe2O3@CuO electrode and Ni(OH)2@CuO as a negative and positive electrode,respectively.The ACS device exhibits a remarkable energy density up to 81.12 Wh kg-1 at a power density of 2.88 W kg-1.Meanwhile,the electrode also showed excellent cycle stability(capacity retention rate after 10000 cycles was 97.9%).