Synthesis And Electrochemical Performance Of N-Doped Corncob Porous Carbon/Cobalt Selenide Electrode Materials

In recent years,the environmental crisis caused by the energy crisis and the burning of fossil fuels has become increasingly serious,prompting the development of green energy（such as solar energy,wind energy,tidal energy）,the use of low carbon dioxide emissions hybrid vehicles,electric vehicles to replace polluting internal combustion vehicles has become an inevitable development trend.Solar energy,wind energy,etc.are intermittent energy sources.Before connecting to the grid or the consumption of electrical appliances,storage equipment consumes a lot,which is not conducive to the storage of these energy sources.Electric vehicles also urgently need excellent energy storage devices,so the development of efficient energy storage equipment has become a coming research hotspots.However,the performance of the device still cannot meet the cammercial needs.For example,the carbon-based has a long working life but the C_m value is very sma1l and the transition metal compounds with high theoretical specific capacity tend to aggregate to affect the conductivity.Therefore,the synthesis of nano porous electrode materials that are not easy to agglomerate and have high electrical conductivity is a solution for producing excellent energy storage devices.In this paper,the synthesis process of N-doped corncob base carbon and cobalt selenide is improved.The results obtained through performance comparison are as follows:（1）Tube furnace carbonization process changes the activation temperature and nitrogen doping ratio to synthesize N-doped corncob-based porous carbon,with KOH as the activator and urea as the nitrogen source,the corncob-based porous carbon TC-800-4 synthesized at 800 ℃has the best performance.At a current density of 1 A g^-1,the C_m value of TC-800-4 is 378.50 F g^-1,the TC-800-4//TC-800-4 device assembled by TC-800-4 has a C_m value of 225.8 F g^-1 at 1 A g^-1,with a high energy density of 27.84 Wh kg^-1 1 and The power density is 1249.99 W kg^-1,The TC-800-4//TC-800-4 device maintained a 92.99%C_m value after 5000 cycles at 5 A g^-1.（2）The N-doped corncob base carbon was synthesized by the hydrothermal process of the reactor and the effects of the concentration of the precursor liquid and the activation temperature on the performance were studied.With KOH as the activator and wea as the nitrogen source,the corncob-based porous carbon HC-8-800-N synthesized at 800 ℃ has the best performance.C_m value is 245.90 F g^-1 at 1 A g^-1;HC-8-800-N//HC-8-800-N device assembled by HC-8-800-N,at 1 A g^-1,the C_m value is 175.60 F g^-1.with a high energy density of 24.39 Wh kg^-1 and a power density of 1003.47 W kg^-1.The HC-8-800-N//HC-8-800-N device maintained a 94.52%C_m value after 5000 cycles at 5 A g^-1.（3）Cobalt selenide is compounded with graphene oxide（GO）to synthesize high conductivity and high electrochemical activity rGO-x/Co_0.85Se composite material rGO-x/Co_0.85Se synthesized when GO is 15 mg has the best dispersibility and the highest specific surface area.The C_m value at a current density of 1 A g^-1 is 1507.50 F g^-1.rGO-15/Co_0.85Se//AC device assembled by rGO-15/Co_0.85Se,at 1 A g^-1 the C_m value is 170.88 F g^-1,with a high energy density of 60.76 Wh kg^-1 and a power density of 1000.00 W kg^-1.The rGO-15/Co_0.85Se//AC device maintained a C_m value of 80.40%after 5000 cycles at 5 A g^-1.（4）Optimize the cobalt selenide synthesis process to reduce the amount of hydrazine hydrate without affecting the performance of the material and study the effect of the amount of NaOH added on the performance of the cobalt selenide material.The C_m value of NaOH-50/Co_0.85Se synthesized with 50 mg NaOH at 1 A g^-1 was 1756.00 F g^-1.NaOH-50/Co_0.85Se//AC device assembled by NaOH-50/Co_0.85Se,at 1 A g^-1,the C_m value is 183.10 F g^-1,with a high energy density of 65.10 Wh kg^-1 and a power density of 800.00 W kg^-1.The NaOH-50/Co_0.85Se//AC device maintained a 90.40%C_m value after 5000 cycles at 5 A g^-1.The high-performance cobalt selenide process synthesize by this process will make a great contribution to electrochemical energy storage in the future.