| Zinc ion hybrid supercapacitor(ZHSC/ZHC)is an emerging charge storage device,which has the advantages of high energy density,high power density and long cycle life.ZHC is mainly composed of battery-type electrode,capacitor-type electrode and zinc salt electrolyte.The energy storage mechanism is mainly classified into two types: Zn2+ ion deposition/tripping on the zinc anode(Faraday reaction)and ion surface adsorption/desorption on the capacitor-type cathode(EDLC).At present,the main problems of ZHC are low capacitance,poor cycle stability and device failure caused by dendrite growth.Therefore,modification and optimization of anode,preparation of highperformance cathode and selection of appropriate electrolyte have become the focus of ZHC research.Among them,carbon material is the most widely studied cathode material of ZHC,and which is the determining the specific capacity and energy density of the capacitor.How to design and regulate the pore structure,microstructure and heteroatomic doping of carbon materials have always been the core problem of supercapacitors.Based on this point,cross-linked porous carbon nanosheets with different pore structures were prepared by using homemade hard templates coupled with potassium carbonate activation and the small molecule compound anthracene as the carbon source in this thesis.Then,the structural characterization and electrochemical performance of the as-prepared carbon material were tested,and the charge storage ability them was analyzed.Next,the influence of carbon materials’ physical and chemical properties,electrolyte’s concentration and type on the electrochemical performance of ZHC wasstudied,and the storage mechanism of ZHC was discussed.The main contents are as follows:(1)The porous carbons with different pore structures were prepared by one-step activation method using aromatic small molecule anthracene as carbon source,homemade KCl+Fe3O4 mixture as template and K2CO3 as activator.The effect of template addition amount on the morphology and pore size distribution of porous carbon material was investigated.The obtained C-0.6 has a micro-mesoporous carbon sheet structure with a specific surface area of up to 2085.11 m2 g-1.At the same time,the supercapacitor(SC)and ZHC properties of the as-prepared porous carbon materials in 6 mol L-1 KOH solution and 2 mol L-1 Zn SO4 solution were studied.At the current density of 0.05 A g-1,the specific capacitance and energy density of SC are 183.49 F g-1 and 6.36 Wh kg-1,respectively.ZHC has a specific capacity of 181.67 m Ah g-1 and an energy density of up to 145.2 Wh kg-1.(2)Flake porous carbon materials were prepared by one-step method,the anthracene as precursor,KCl+Mg O mixture as template and K2CO3 as activator.The effects of different calcination temperatures on the composition and morphology of the template were investigated.When the calcination temperature is 800 ℃,the template presents nanoscale Mg O particles.The influence of the template with different composition and structure on the pore structure and microstructure of the porous carbon material were investigated.The specific surface area of C-800 is as high as 907.91 m2 g-1,and the proportion of micropores is 34.48%.The ZHC performances of porous carbon in 2 mol L-1 Zn SO4 solution were tested,and the specific capacity is 114.54 m Ah g-1 at the current density of 0.05 A g-1.At the same time,the concentration of Zn SO4 electrolyte was adjusted to 1 mol L-1 and 3 mol L-1 to analyze the effect of electrolyte concentration on the charge storage performance of ZHC.C-800 was found to have higher capacity performance in 3 mol L-1 Zn SO4.The ZHC displays a high specific capacity of 121.68 m Ah g-1(0.05 A g-1)and a high energy density of 109.31 Wh kg-1(33.46 W kg-1).The capacitor manifests excellent cycle stability with 96.2% capacitance retention after 30000 cycles at the current density of 5 A g-1.(3)Using anthracene as carbon precursor,single KCl as template and K2CO3 as activator,porous carbon nanosheets were prepared by one-step method.The effects of melamine polyphosphate(MP)on the pore structure and microstructure of carbon materials were studied.The results show that MP,as a pore-forming agent,contributes to the formation of mesopores and macropores,thus increasing the specific surface area and pore capacity of porous carbon.The specific surface area of C-3-25 is 1466.33 m2 g-1,and the specific surface area of micropores is 773.84 m2 g-1.The performance of porous carbon in 3 mol L-1 Zn SO4 solution and 3 mol L-1 Zn(CF3SO3)2 solution was comparatively.In 3 mol L-1 Zn SO4 electrolyte,the specific capacity of ZHC reaches134.27 m Ah g-1(0.05 A g-1).The energy density and power density reaches 101.49 Wh kg-1 and 13400 W kg-1,respectively.In 3 mol L-1 Zn(CF3SO3)2 electrolyte,the specific capacity of ZHC is 142.40 m Ah g-1(0.05 A g-1),the energy density is 127.95 Wh kg-1(23W kg-1),the power density is 12,000 Wh kg-1(42.56 Wh kg-1),and the capacity retains74.84% of the original capacity is after 50000 cycles at the current density of 5 A g-1. |
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