Preparation Of Loaded Mo₂C/CF Composites And Their Applications In Supercapacitors

The consumption of traditional fuels will lead to a large amount of CO₂ emissions,climate change and serious environmental pollution.In order to achieve sustainable economic growth and environmental balance,the search for clean and renewable energy sources is critical.Most batteries suffer from low power transmission and can’t meet the energy requirements for faster,higher power.Supercapacitors are electrochemical energy storage devices that provide higher power density than batteries.There are many factors that affect its performance,among which electrode material is the most important one.At present,the common electrode materials are mostly single materials.Although the common double-layer materials have high electrochemical stability and long cycle life,they have low theoretical specific capacity.Pseudocapacitance materials have the advantages of high theoretical specific capacity,but their cycling stability is poor.But the composite material generally has the higher specific capacity and the better circulation stability,therefore the composite material research becomes the research hotspot of the capacitor.Carbon fiber（CF）was prepared by electrostatic spinning with polyacrylonitrile（PAN）and N,N-dimethyl formamide（DMF）as raw materials.Molybdenum carbide（Mo₂C）was prepared by sol-gel method with ammonium molybdate and glucose as raw materials.Mo₂C-CF and Mo₂C/CF composites were prepared by electrostatic spinning method and ball-milling method.In order to study the electrochemical properties of electrode materials in different electrolytes,tests were performed in 1M H₂SO₄,1M KOH and 1M Na₂SO₄electrolytes.It was found that in 1M H₂SO₄ electrolyte,Mo₂C-CF and Mo₂C/CF had a more obvious redox peak than Mo₂C.The equivalent series resistances（Rs）of Mo₂C-CF and Mo₂C/CF composites are 0.8Ωand 0.9Ω,which are lower than the equivalent series resistance（4Ω）of Mo₂C,which proves that the composite material resistance is small.When the current density is 0.25 A g^-1,the specific capacitance of Mo₂C is only 64.7 F g^-1,while the specific capacitance of the load electrode materials Mo₂C-CF and Mo₂C/CF can reach 270.0and 298.8 F g^-1.At the current density of 5.0 A g^-1,the discharge capacity of the composite material is 118.8 and 100.0 F g^-11 is much higher than 21.2 F g^-11 of Mo₂C.Thus,the composite material has better multiplier performance.At the current density of 1.0 A g^-1,the capacity retention rates of the composites after 10,000 constant current charges and discharges were87.39%and 91.53%,higher than 79.81%of CF and 41.08%of Mo₂C,indicating that the composites had a better electrochemical stability.Therefore,the preparation of loaded electrode materials for supercapacitors is a potential way to improve the specific capacity and stability of the devices.