Preparation Of Biomass-Based Porous Carbon Material And Its Application In Supercapacitors

With the consumption of fossil energy and the deterioration of the environment,it is urgent to develop environmentally friendly,renewable and high-performance energy storage equipment.Among them,the supercapacitor has received extensive attention.Biomass carbon materials are ideal candidate materials for supercapacitors due to their excellent electrochemical performance,abundant quantity,low cost,renewable and environmental friendliness.This paper will introduce the work of preparing supercapacitors using two kinds of waste biomass.The main work is as follows:（1）Using discarded lemon peel as carbon precursor,ANC-800 was prepared by pre-carbonization at high temperature for 2 h,and then activated at high temperature with urea as nitrogen source and KOH as activator under the protection of high purity N₂.It has a specific surface area of 1739 m² g^-1,a doping amount of N element of 2.24 at.%and a hierarchical porous structure,which improve the electrochemical performance of carbon materials.The specific capacitance measured at 0.5 A g^-1 in A three-electrode system is 333.6 F g^-1.The capacitor retention rate of ANC-800 at 5A g^-1 for 10000 cycles is as high as 96.1%,which indicates that ANC-800 has good cycle stability.The assembled all-solid symmetric supercapacitor shows an energy density of 14 W h kg^-1 at a power density of 1124.6 kg^-1,indicating that the prepared carbon material is a very promising energy material.（2）Activated N/P co-doped carbon（A-NPC）materials with ultrahigh specific surface area and hierarchical porous structures were synthesized by a green and cheap method to enhance the electrochemical performance of electrical double-layer capacitors.Waste durian peel was used as a carbon precursor,（NH₄）₂HPO₄ as N and P sources,and KOH as an activator.The obtained porous carbon material had an ultrahigh specific surface area(3416 m² g^-1),a hierarchical porous structure（84 vol%micropores）,and appropriate N（2.17 at.%）and P（0.48at.%）doping amounts.Synergy among these characteristics enabled the A-NPC to exhibit exciting specific capacitance(383.4 F g^-1 at 0.5 A g^-1),ideal rate performance(255.6 F g^-1 at20 A g^-1),and fantastic cyclic performance(98.3%capacitance retention after 10 000 cycles at5 A g^-1)in the three-electrode device.This material could provide an energy density of 25.3 W h kg^-1 when the power density was 400.5 W kg^-1,to all-solid-state symmetrical capacitors and presented good cycle performance with a cycle retention rate of 97.6%at 2 A g^-1 after 5000cycles.A-NPC has potential value in the field of energy materials due to its excellent performance.