Synergistic Effect of Salt+Alkali on the Electrochemical Performance of Carbon Electrode Materials
As a new type of energy storage and conversion device,supercapacitors are highly praised for their fast charging and discharging speed,long service life,safety and environmental protection.Among them,electrode materials for supercapacitors have always been the focus of research.Considering the factors such as raw material source,price and preparation process,porous carbon electrode materials have become the first choice.Salt template method and KOH chemical activation method are common methods for preparing porous carbon electrodes.The former has complex operation,but the pore structure of the product is mainly mesoporous.The latter activation product has a large specific surface area,which can accurately control the pore size distribution and pore volume of the porous carbon electrode,but the porous carbon activated by this method is mainly micropores.If the two are combined to form complementary advantages and jointly construct a reasonable carbon material structure,it will help to improve the electrochemical performance of porous carbon electrodes.The electrode materials were prepared by a combination of template and chemical activation using the raw coke powder of needle coke,a solid waste in the lithium battery anode industry,as raw material.The effects of the addition ratio of salt(KCl)and alkali(KOH)on the electrochemical properties of carbon electrode materials were investigated.The results show that the carbon structure of the porous carbon samples prepared by the combination of the two methods is mainly amorphous carbon with more surface defects,and the amorphous carbon increases with the increase of KOH addition,but the addition of excessive KOH does not increase the content of amorphous carbon.In the three-electrode test analysis,it was found that the sample PC-2 showed excellent capacitance performance,and the mass specific capacitance reached 266.9 A·g-1 at a current density of 1 A·g-1.At a high current density of 10 A·g-1,the capacity retention rate is as high as 79.4%.The internal resistance of the electrode material is only 0.67 Ω,and the electric double layer capacitance performance has a very short response time.Therefore,when the mass ratio of raw material,KCl and KOH is 1∶3∶2,the synergistic activation effect of KCl and KOH is the best,which greatly improves the charge transport capacity of carbon electrode materials,and can effectively shorten the diffusion path of electrolyte ions in the material,showing a faster charge and discharge rate.
supercapacitorcoke powdercarbon electrode materialsynergistic effectcapacitance performancemass specific capacitancerelaxation timerateability
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