Preparation And Properties Of Manganese Silicate As Electrode Material For Supercapacitor

In order to satisfy the increasing energy and power demand of energy storage system,the development of reliable and efficient energy storage system has been paid more and more attention.The search for suitable electrode materials for electrochemical storage devices has led to the development of new electrode materials.Among actively studied electrode materials,phosphide compounds with metallic features are recognized as promising supercapacitor materials.The specific research contents of this thesis are as follows:1.Preparation,structure and properties of cobalt nickel phosphate thin film electrode materials modified by silver quantum dotsFirstly,NiCo-LDHs hierarchical arrays were grown on a nickel foam substrate by hydrothermal method using nickel nitrate,cobalt nitrate,and hexamethylenetetramine as the nickel source,cobalt sources,and precipitator,respectively.Then,NiCo-LDHs was phosphorized with sodium hypophosphite to obtain NiCoP films.Finally,Ag/NiCoP electrodes were obtained by depositing Ag quantum dots on the NiCoP electrode by magnetron sputtering technology.On this basis,using Ag/NiCoP as positive electrode,AC as negative electrode and KOH/PVA as electrolyte,an asymmetric supercapacitor was constructed,and its energy storage characteristics were studied.Due to the good ohmic contact between Ag quantum dots and NiCoP nanosheets,the Ag/NiCoP exhibited the specific capacitance of 6150 m F/cm~2(3050F/g at 1A/g)higher than the 3445 m F/cm~2(1722 F/g at 1A/g)of bare NiCoP at 2m A/cm~2.By introducing silver quantum dots,the areal specific capacitance was increased by 78.5%.When the current density increased from 2 to 30 m A/cm~2,the capacitance retention of Ag/NiCoP electrode reached 34%.The capacitance retention was 73%at 30 m A/cm~2 for 4000 cycles.These electrochemical performance improvements were attributed to a combination of sufficient electroactive sites,high electric and easy ion diffusion.The assembled Ag/NiCoP//AC asymmetric supercapacitor exhibited an energy density of up to 0.254 m Wh/cm~2 at a power density of 1.88 m W/cm~2.This study provided a way for the design of a new generation of supercapacitors for energy storage devices.2.Preparation,structure and properties of cobalt-nickel phosphide thin film electrode materials modified by carbon quantum dotsFirstly,a bottom-up strategy was adopted to obtain the solution of carbon quantum dots.Secondly,nickel nitrate and cobalt nitrate were used as the sources of nickel and cobalt,respectively,and hexamethylenetetramine was used as the precipitant.The prepared carbon quantum dots solution was added into the mixed solution meanwhile.The uniform C/NiCo-LDHs hierarchical array was grown on the nickel foam substrate by hydrothermal method.Finally,C/NiCoP thin films were obtained by phosphating C/NiCo-LDHs with sodium hypophosphite.The specific capacitance of the C/NiCoP-5 thin film electrode reached 5300.5 m F/cm~2 at 2m A/cm~2 due to its unique hierarchical structure,large specific surface area and superior electrical conductivity.After the introduction of carbon quantum dots,the areal specific capacitance was increased by 53.8%.When the current density increased from 2 to 30 m A/cm~2,the capacitance retention reached 24%.These results indicated that C/NiCoP materials had great application potential in the development of high-performance electrochemical energy storage devices.