Controllable Preparation Of CuCo₂O₄ Hybrid Electrode Materials And Study On The Properties Of Supercapacitive Energy Storage

Severe climate change and limited fossil fuel supply have stimulated researchers to develop clean energy storage devices that have the advantages of high power and high energy density.At present,supercapacitors are one of the most widely used energy storage devices for researchers,mainly because of their advantages of large power density,excellent cycling performance and fast charge-discharge.However,some electrode materials for supercapacitors have hampered their practical application because of their very low conductivity,large variations in their volume during charging/discharging,and poor rate capability.In order to improve the electrochemical performance of supercapacitors,many researchers have started to work on electrode materials with chemical stability and thermal stability such as cobalt-based bimetallic oxides?MCO₂O₄,M=Ni,Mn,Zn,Cu,etc.?.In this paper,we mainly improve the electrode supercapacitor performance by changing the morphology and hybrid design of CuCo₂O₄ to accelerate the electrode reaction kinetics.Nanoporous Cu Co₂O₄ nanowires and nanosheets,CuCo₂O₄@CoMoO₄ and CuCo₂O₄@Ni?OH?₂ core-shell nanocomposites were successfully fabricated on Ni foam by single or combination of hydrothermal method and chemical bath deposition method and its supercapacitor performance has been studied.In order to improve the performance of hybrid supercapacitors?HSC?,CuCo₂O₄@CoMoO₄ nanocomposites were successfully prepared by hydrothermal synthesis and annealing treatment on the basis of a three-dimensional network of Ni foam.With CuCo₂O₄ nanowire as the core,CoMoO₄ nanosheets grow perpendicularly on their surfaces.This kind of core-shell structure with larger specific surface area can increase the ion diffusion and increase the transfer rate.The experimental results show that the CuCo₂O₄@CoMoO₄ hybrid electrode exhibits superior rate performance?which has 481?Ah/cm² at a current density of 5 mA/cm²,334?Ah/cm² at a current density of 80 mA/cm².pure CuCo₂O₄ electrode has 72?Ah/cm² and 19?Ah/cm²at 5mA/cm² and 80 mA/cm²?and good cycling stability?the CuCo₂O₄@CoMoO₄ hybrid electrode has a capacity retention of 84%after 2000 cycles at a current density of 20mA/cm²?,compared to a single CuCo₂O₄ electrode.In this paper,we report a simple method to fabricate the hierarchical three-dimensional CuCo₂O₄@Ni?OH?₂ hybrid nanostructures on Ni foam for supercapacitors.The highly mesoporous and interconnected CuCo₂O₄ nanoflakes are ideal scaffolds for loading electroactive Ni?OH?₂ shell nanosheets,which significantly boost the energy storage efficiency of the integrated system.The optimized CuCo₂O₄@Ni?OH?₂ hybrid electrode delivers a high areal capacity of 439 mAh/cm²at 2 mA/cm² and a good rate capability of 82.7%at 80 mA/cm².In light of these merits,a hybrid supercapacitor?HSC?hasbeen further assembled.The HSC device displays simultaneously high energy and power densities?48 Wh/kg at 468 W/kg,and34 Wh/kg at 9145 W/kg?,as well as good long-term cycling stability.After charging for a short time,two HSC devices connected in series can drive LEDs with different colors efficiently,suggesting the great potential of this hybrid material toward practical applications as advanced electrodes for high-performance HSC devices.