Preparation Of Coconut Shell Activated Carbons By Deep Activation And Their Analysis Of Electrochemical Properties

Electrochemical energy storage device is an ideal energy storage device.Supercapacitor is an emerging electrochemical energy storage device with high power density,long service life and safe and reliable characteristics,which has great application prospects..Activated carbon material is the electrode material of choice for supercapacitors at present,and it is also the most successful electrode material in the commercial application of supercapacitor.Bio-based activated carbon has begun to be applied to the market.In this paper,commercial coconut shell activated carbon,which has been physically activated before being put on the market,is used as a raw material,and the depth is prepared by an alkali liquid impregnation method(AI),an alkali carbon physical blending method(APB)or an activation method combining impregnation and physical blending.Activated coconut shell activated carbon.(1)The two-stage activation:Samples were obtained by a treatment method of AI and APB;(2)three-stage activations:Samples were obtained by a treatment method using AI-AI,AI-APB,APB-AI,and APB-APB.The samples were characterized by specific surface area pore size analyzer,Fourier transform infrared spectroscopy,constant current charge and discharge analysis,cyclic voltammetry analysis and AC impedance analysis.The impregnation concentration,alkali carbon blending ratio and activation time were analyzed.The effects of process conditions such as activation temperature on the microstructure and chemical composition and electrochemical properties of coconut shell activated carbon.The two-stage activation results show that compared with APB,the AI method for the preparation of coconut shell activated carbon can reduce the amount of KOH,reduce the corrosion of equipment during the activation process,and improve the efficiency of the activator.Under the three-electrode system,activated carbon prepared as an electrode material with an immersion concentration of 14 mol/L,an activation time of 60 min and an activation temperature of 800°C(ACJK-c14)has the best electrical properties at a current density of 1 A/g.The lower specific capacitance is up to 234 F/g,which is 94 higher than the original coconut shell activated carbon(specific surface area 750.2 cm~2/g)as the specific capacitance of the electrode material(140 F/g at a current density of 1 A/g).F/g.ACJK-c14 has a specific surface area of 1500 cm~2/g,a total pore volume of 0.716 cm~3/g,and an average pore diameter of 1.91 nm.The optimum alkali carbon ratio of the AI method is 3:2,the optimum conditions for the activation temperature are 800 ~oC,the optimum conditions for the activation time are60 min,and the specific capacity is 241 F/g.The specific capacitance of the sample prepared by the APB method is slightly higher than that of the sample prepared by the AI method,but the KOH content is much higher,so the activation efficiency of the AI is superior.The results of three-stage activations showed that most of the activated coconut shell activated carbon had higher specific surface area and electrochemical performance,and the electrochemical performance of a few samples was lower than that of secondary activation.In all three activation experiments,the APB-AI method was used(the conditions of APB were:alkali carbon ratio of 3:2,activation time of 60 min,activation temperature of 800 ~oC;AI conditions were:impregnation concentration of 8 mol/L,activation time of 60 min,activation temperature of 800 ~oC)treated coconut shell activated carbon as electrode material,its specific capacitance can reach 367 F/g at a current density of 1 A/g,specific surface area of up to 2688 cm~2/g.The cycle performance test was carried out,and the specific capacitance value of 91%was maintained after 5000 cycles.The activated carbon sample after deep activation is mainly microporous,and the specific surface area and its specific capacitance as the electrode material are greatly improved.