Preparation And Ultracapacitance Properties Of CoFe-Based Materials Electrode With Multidimensional Hybrid Structure

Supercapacitor（SCs）is a new type of green energy storage device,which has the advantages of high specific power,high charging and discharging efficiency,and long service life.It shows a great promise for application in the era of low carbon economy.However,the large-scale commercial application of devices prepared based on prior art is limited due to the low energy density and poor cycle life caused by volume expansion of electrode materials during charging and discharging.As the core component of supercapacitor,electrode material has a crucial effect on the energy storage performance of supercapacitor.The adjustment of electrode material composition and structure is the key to realize high performance supercapacitor devices.Therefore,in this article,high performance and unique nanostructured supercapacitor electrode materials were prepared by using high conductive nickel foam（NF）as the growth substrate and transition metal Co,Fe and Mn compounds as the electrode materials.Specific work content:1.A simple one-step hydrothermal method was used to generate Co-Fe hydroxide carbonate（Co-Fe CH）electrode materials with nanorod structure on nickel foam substrates,which exhibited high specific capacity and rate capability.The area specific capacity was 3.85 F/cm² at a current density of 10 m A/cm²,and 2.08 F/cm² when the current density was increased to 40 m A/cm².The Co-Fe-Mn electrode materials with multidimensional hybrid nanostructures were prepared by the Co-Fe CH compounded with Co-Mn layered double hydroxide.The unique morphological structure can effectively promote electron transfer and ion diffusion,which enables the Co-Fe-Mn electrode to exhibit excellent electrochemical performance.The area specific capacity reached 7.33 F/cm² and 3.93 F/cm² at current densities of 10 m A/cm² and 40 m A/cm²,respectively.Meanwhile,the Co-Fe-Mn//AC asymmetric supercapacitor device prepared with Co-Fe-Mn as the positive electrode and AC as the negative electrode achieved an energy density of 0.723 m Wh/cm²at a power density of 8.53 m W/cm².The device retained 101.72%of its initial capacity after 5500 cycles at a current density of30 m A/cm²,exhibits excellent energy storage characteristics.2.The precursor Co-Fe CH was converted to Fe Co₂S₄ by hydrothermal method.The Fe Co₂S₄ nanorods provide a mass of electrochemical active sites and modify the ion transfer pathway of the Faraday redox reaction,exhibiting an outstanding area-specific capacitance（10.73 F/cm² at 10 m A/cm²）and excellent rate capability.The Fe Co₂S₄//AC quasi-solid-state asymmetric supercapacitor assembled on this basis achieves energy densities of 1.17 m Wh/cm² and 0.48 m Wh/cm² at power densities of13.5 m W/cm² and 108.7 m W/cm²,respectively.The device retains 92.57%of its initial capacitance after 2000 cycles at a current density of 30 m A/cm²,indicating the excellent electrochemical performance.