Research Of Carbon-based Electrode For Sodium-ion Batteries

With the rapid development of society,the depletion of traditional fossil energy represented by petroleum forces the renewable energy to become the demand of sustainable development of society.Lithium-ion batteries(LIBs)have been successfully commercialized,which due to their high energy density,good power density and reliable safety.However,the uneven distribution of lithium resources and the price of some transition metal elements make LIBs difficult to apply to the large-scale energy storage facilities.Benefit to the abundant sodium resources and the similar mechanism of sodium ions and lithium ions in the electrochemical energy storage,researchers have recently set off a research upsurge on sodium ion batteries(NIBs).However,Na~+can not be inserted into graphite layers in general ester based electrolytes,the lack of suitable anode materials limits the commercial application of NIBs.This paper develops and studies two kinds of carbon-based anode in NIBs and explores the electrochemical behavior of ether electrolyte on graphite and hard carbon materials.The specific work is as follows:(1)The development of low-cost biomass and the preparation of hard carbon with stable electrochemical properties are the key factors for its application in NIBs.Biomass hard carbon for NIBs was prepared from waste Sichuan pepper.Through the different temperature of carbonization(1000-1600°C),different microcrystalline graphite structure hard carbon are synthesized for electrochemical tests in NIBs.The results show that a certain degree of short-range microcrystalline graphite for Na~+-insertion and high coulomb efficiency.(2)For the anode materials of NIBs,the degree of graphitization is closely related to the performance of Na-storage.Nano ZIF-8s are used as the amorphous carbon-based material precursor.ZIF-8s nanocrystals were grown in-situ on graphene and carbon nanotubes with carbon crystal characteristics by means of electrostatic self-assembly to form a graphite crystalline-ZIF-8s composite material.Porous carbon with crystal-amorphous multistage structure was prepared by high-temperature pyrolysis and pickling.The electrochemical properties of amorphous N doped porous carbon with different graphite crystalline are studied.The results show that graphene-CNT-N doped3D composite carbon has greater pseudo capacitance effect and the best electrochemical properties.(3)In view of the different carbon materials have different electrochemical process when the ethers electrolyte for NIBs.This work is mainly through the comparison of the ethers and esters electrolyte in the graphite(G),amorphous carbon(HC)hard carbon electrochemical properties,microstructure,surface functional groups,and the Na~+diffusion coefficient to explore factors of ether and ester based electrolyte in enhance Na storage of hard carbon.