Three-dimensional High Conductance Pseudocapacity Carbon Material And Pre-lithiation Technology

Lithium ion capacitor(LIC)has been regarded as the development direction of new electrochemical energy storage devices with high energy and power density in the future due to their characteristics of integrating lithium-ion batteries(LIB)and traditional supercapacitors(SC).One of the important factors affecting the performance of LIC is the activity and efficiency of electrode materials.So it is extremely necessary to find electrode materials with good structure and excellent performance.Among them,due to the advantages of high specific surface area,controllable pore structure,relatively good mechanical stability and electrical conductivity,metal organic framework(MOFs)derived carbon has become the best choice of electrode materials.Based on this,a series of new MOFs carbon materials were designed and prepared in this paper,which were assembled into three-dimensional carbon materials by electrospinning and introduced into heteroatoms.In addition,in order to explore the influence factors of improving the energy density and magnification performance of lithium-ion capacitors,various indexes of pre-lithiation technology were analyzed.The main research content is divided into the following three parts:(1)Using copper as a transition metal ion,a series of crystalline porous materials were formed by self-assembly of different organic ligands.MOFs with high porosity and large specific surface area were prepared by calcining them at high temperature.The most suitable organic ligand,proportion and calcination temperature were selected by SEM,XRD and electrochemical performance tests.The results show that at 800°C,using 1234-butane tetracarboxylic acid(BTCA)as the organic ligand,and the ratio of organic ligand and copper ion is 1.5,the carbon material prepared has better performance,and it is also used as the carbon material(BTCA-Cu1)for the work in this paper.(2)The carbon based materials were mixed with polyacrylonitrile(PAN)in different proportions in N,N-dimethylformamide(DMF).The phase structure and electrochemical properties of three dimensional carbon composites assembled by electrospinning were studied.In addition,heteroatomic nitrogen(N)and PVP with low carbonization rate were introduced on the basis of three-dimensional composite carbon materials to improve the pseudo capacitance effect of carbon materials,and the effects of different doping concentrations on the properties were compared.This series of studies showed that the introduction of carbon nanofibers would reduce the specific surface area of the material,but the PAN-based three-dimensional structure had a larger mesoporous structure,and the appropriate introduction of N and PVP would improve the performance of the pseudocapacitance.(3)Two carbon materials with different phase structures,sucrose based hard carbon and BTCA-Cu1,were assembled into LIC with activated carbon,respectively.The differences in unembedded lithium,electrochemical(EC),internal short(IS)with different duration and different lithium sources were investigated.Based on this,IS method was chosen to conduct 12 h pre-lithiation treatment on three-dimensional composite carbon materials made by electrospinning and doping with nitrogen or PVP,and the effect of the three-dimensional structure and heteroatom pre-lithiation were studied.