Preparation Of Porous Carbon And The Performance Of Supercapacitors By Potassium Salt Activation

As the requirement of energy consumption grows,it is imperative to develop sustainable and efficient energy storage devices to address the over-consumption of fossil fuels.Supercapacitors are a promising application for electrochemical energy storage devices due to their fast charge and discharge rates,high power density and stable cycling performance,but their energy density still faces significant challenges.Porous carbon materials are widely employed in supercapacitors due to their large specific surface area,favorable electrical conductivity and cheap accessibility.The specific surface area,pore structure and surface properties of the material greatly influence the electrochemical properties of carbon materials.Therefore,the preparation of porous carbon with higher specific surface area,proper pore structure and abundant heteroatom（O,N,S,etc.）doping is beneficial to significantly improve its electrochemical performance.In this paper,porous carbon materials with good properties were prepared using different carbon precursors and potassium salt activators,the main studies of which are as follows:（1）Three-dimensional interconnected porous carbon（IPC）was prepared with alkali metal organic salt potassium stearate as carbon precursor and potassium bicarbonate（KHCO₃）as activator,and the influence of different carbonation temperatures on the electrochemical performance of the prepared porous carbon was explored.IPC-700 has a porous carbon skeleton with three-dimensional interconnection,high specific surface area(932.0 m²g^-1)and abundant O element doping.The IPC-700 electrodes can achieve a specific capacitance of261.3 F g^-1at a current density of 0.5 A g^-1and have superior cycling performance with 99.7%capacitance retention after 10,000 charge/discharge cycles.In addition,the IPC-700 electrodes are used as positive and negative electrodes to assemble symmetric supercapacitors.The assembled symmetric supercapacitors have a stable electrochemical performance and can achieve an energy density of 13.8 Wh kg^-1at a power density of 300 W kg^-1.This is because the three-dimensional interconnected porous structure can accelerate the ion transfer in the process of charge and discharge,and the doped O atoms can improve the surface wetting of electrode materials and promote the formation of partial pseudocapacitance,thus providing some research basis for the fabrication and improvement of supercapacitor electrode materials.（2）O-doped hierarchical porous carbon（HPC）was synthesized using biomass material wood powder as carbon precursor and KMn O₄as activator and template agent and the electrochemical performance of the carbon materials prepared at different carbonization temperatures were also investigated.The optimized HPC-600 samples have a hierarchical porous structure,a high specific surface area(954.3 m²g^-1)and an abundance of oxygen-containing functional groups.A specific capacitance of 362.7 F g^-1was achieved at a current density of 0.5 A g^-1and 173.3 F g^-1at a high current density of 50 A g^-1.The HPC-600electrode showed no significant capacitance decay after 10,000 cycles,indicating good rate and cycling performance.In addition,symmetric supercapacitors were assembled using HPC-600as positive and negative electrodes,and the assembled symmetric supercapacitors showed good cycling stability with an energy density of 18.4 Wh kg^-1at a power density of 600 W kg^-1,which offers a novel approach to synthesize porous carbon materials from biomass carbon precursors and their applications in supercapacitors.