Preparation And Electrochemical Properties Of Biomass Carbon Material Derived From Corn Stalks

Until now,lithium-ion battery has been the most potential energy storage power source due to its many advantages such as high operating voltage,high energy density,low self-discharge rate,and environmental friendliness.A successful factor of lithium-ion battery is that the anode material can reversibly intercalate/intercalate lithium ions.At present,in practical applications,the anode materials for lithium-ion battery are mostly graphite materials,but its capacity can not meet the growing energy demand.And with the reduction of graphite resources,the research focus of lithium-ion battery in the future will move toward high Coulomb efficiency,high cycle performance,and low cost.Corn stalks are agricultural wastes which are cheap and widely sourced but have not been used reasonably and effectively in agricultural production.The preparation of anode materials for lithium-ion battery using corn stalks as raw materials not only makes rational use of agricultural waste,but also effectively alleviates environmental pollution and energy crisis.In this paper,agricultural waste corn stalks were used as raw materials,and different activators and methods were used to prepare porous biomass carbon materials.The physical characterization and electrochemical performance of biomass carbon materials were tested.The main research contents and results are as follows:?1?After separating the cortex and core of corn stalks,corn stalks core was selected as raw material.Using KOH as an activator,porous biomass carbon was prepared by activation after pyrolysis and carbonization.The specific surface area was1266.83 m² g^-1,and the pore size distribution was mainly 2-20 nm.As the anode material for lithium-ion battery,the discharge capacity of biomass activated carbon electrode was 504 mAh g^-11 after 100 cycles of at current density of 0.2 C.When the current density was 5 C,the discharge specific capacity was 275 mAh g^-1.Compared with the unactivated biomass carbon material,the mesoporous structure of porous biomass activated carbon significantly improved the electrochemical performance of the battery.?2?The porous biomass carbon material was prepared by carbonizing and activating after corn stalks impregnated with CaCl₂ solution.The effects of different activation temperature and amount of CaCl₂ on the pore structure and properties of corn stalks biomass carbon materials were investigated.When the activation temperature was 600?and the mass ratio of corn stalks and CaCl₂ was 1:2.5,the pore structure of biomass carbon materials was more abundant,and the cycle performance and rate performance were more excellent.The discharge capacity after100 cycles at 0.2 C was 783.8 mAh g^-1.Even at a high current density of 10 C,the specific capacity can even achieve 347 m Ah g^-1.These results can be ascribed to the larger specific surface area and the rich pore structure,which increased the contact area and permeability of the reactants with the electrolyte,and provided more free movement space for the intercalation/delamination of lithium ions.?3?Using corn stalks as raw materials to obtain industrial raw materials with high added value such as xylose,alkali lignin and glucose by hemicellulose hydrolysis,lignin extraction and cellulose hydrolysis.These products can be processed with high added value.The remaining residue was used to prepare porous biomass carbon,which ultimately enabled the comprehensive utilization of corn stalks.Through SEM and TEM analyses,it can be seen that the prepared residue carbon had a coexisting structure of hollow carbon microspheres and mesoporous carbon.The electrochemical results showed that the initial discharge capacity was 1116.8 mAh g^-1at current density of 0.2 C,and retained 438.9 m Ah g^-11 after 100 cycles.