Preparation And Properties Of Biomass Porous Carbon Anode Materials For Potassium Ion Batteries

As the demand for energy in human society is growing,the global energy crisis is intensifying.And there is an urgent need to develop new energy sources to solve the problem of depletion of fossil fuels.Reusable,environmentally-friendly,and inexpensive electrical energy storage systems for secondary batteries have attracted widespread attention.Currently,lithium ion batteries have been used in electric vehicles and portable electronic devices due to their excellent electrochemical performance.Among them,potassium and lithium belong to the same main group.They exhibit similar physical and chemical properties.Therefore,potassium ion batteries have become a hot topic for researchers.In this paper,the potassium storage performance of biomass anode materials is studied.Biomaterials with the properties of widely distributed,non-toxic,environmentally-friendly are promising precursors for carbon materials.We use the potato biomass as a precursor.And by secondary carbonization,an amorphous porous carbon material was prepared as an excellent anode material for potassium-ion batteries.The specific research contents are as follows:?1?A porous carbon anode material was synthesized by a secondary carbonization method using resource-rich potato biomass for the first time.The microstructure of potato biomass porous carbon?PBPC?was studied by X-ray diffraction?XRD?,Raman spectroscopy?Raman?,scanning electron microscope?SEM?,transmission electron microscope?TEM?and N₂ adsorption desorption isotherm method.The electrochemical properties of PBPC materials were studied by battery test system and electrochemical workstation.The electrolyte was a 3M potassium bis?fluoro-slufonyl?imide?KFSI?dissolved in dimethyl ether?DME?.The button type potassium ion half-cell was prepared and the potassium storage of the material was studied.It was found in the experiment that the reversible specific capacity reached 248 mA h g^-1 at100 mA g^-1,and the capacity retention ratio after 100 cycles was 91.7%.Moreover,under the high current density of 1000 mA g^-1,the reversible specific capacity was still152 mA h g^-1,showing its excellent rate performance.?2?The effect of carbonization temperature on biomass materials was studied.In the process of preparing carbon materials,the pre-pyrolyzed potato biomass was selected as the precursor,and the carbonization temperature range was 900-1100°C.The results show that different carbonization temperatures affect the structural properties of biomass materials.When the secondary carbonization temperature is1000°C,the porous carbon material PBPC-1000 prepared by potato exhibits higher charge-discharge specific capacity and superior rate performance.In order to further explore the mechanisms responsible for such excellent electrochemical performance of PBPC-1000.The cyclic voltammetry curves of PBPC-900,PBPC-1000 and PBPC-1100at different scan rates were tested.The kinetics of electrons and ions during electrode reaction were analyzed and the diffusion coefficients of K⁺in different electrode materials were calculated.The results fully proved that the potassium storage performance of potato biomass materials with the carbonization temperature of 1000°C was the best.