Preparation Of Porous Activated Carbon Derived From Shoot Shells And Its Supercapacitor Performances

As a new type of energy storage device,supercapacitor has a wide range of applications in electric vehicles and portable electronic products due to its high specific capacity,high power density,fast charge and discharge,long life and no pollution to the environment.As the core component of supercapacitors,electrode materials have become a hot spot for researchers in recent years.The biomass based activated carbon material having high specific surface area and rich pore structure has a wide range of raw materials for production,is recyclable,and has a simple manufacturing process.In this paper,the domestic waste bamboo shoot shell is used as biomass carbon precursor and activated under different activators.The effects of different activators on the electrochemical performance of the obtained activated carbon were investigated.Based on above results,the influence of the impurity atomic sulfur on the electrochemical performance of porous carbon as electrode material for supercapacitors is further explored.The main research contents are as follows:1.The biological waste bamboo shoots shells are carbon,nitrogen,oxygen source,and potassium hydroxide and zinc chloride are used as activators.N and O co-doped layered porous activated carbon was prepared by one-step carbonization activation.The results show that the porous activated carbon obtained by different activators has different degrees of atomic doping and pore size distribution.The heteroatom-doped porous activated carbon prepared based on KOH activation exhibits relatively better electrochemical performance as electrode material for supercapacitor.The symmetric supercapacitor has gravimetric and volumetric capacitance of 223.21 F/g and 167.63F/cm³,respectively,at current density of 1 A/g in 1 M H₂SO₄ electrolyte.The supercapacitor also delivers a high energy density of 13.15 Wh/kg at power density of546.60 W/kg in 1 M Na₂SO₄ electrolyte,as well as high capacitance retention rate of93.62%after 4000 cycles at 5 A/g.2.The biological waste bamboo shoots shells are used as carbon,nitrogen and oxygen sources.After being processed by a ball mill,they become powdered biomass particles.Using EDOT as a sulfur source,PEDOT was grown on the surface of powdered biomass particles by in situ polymerization.The resulting mixture is subjected to one-step carbonization activation to obtain an N/S-codoped porous activated carbon.This method overcomes the shortcomings of the biomass itself without S doping and introduces a large number of dopant atoms.The experimental results show that compared with pure biomass based activated carbon,the introduction of S atoms makes the obtained materials having a certain improvement in the electrochemical performance.The symmetric supercapacitor based on the doping material has gravimetric capacitance of 302.5 F/g at current density of 0.5 A/g in 1 M H₂SO₄electrolyte.The electrode material has an energy density of up to 30.60 Wh/kg at a power density of 468.75 W/kg in 1 M EMIMPF₆ electrolyte,as well as high capacitance retention rate of 82%after 3000 cycles at 5 A/g.Finally,the feasibility of preparing materials in practical application is verified by lighting LED.