Study On The Lithium-ion Capacitors Based On Metal Oxide Anode Materials And Their Electrochemical Performance

Lithium-ion capacitor has the high energy density of lithium ion batteries and high power density and long cycle life of supercapacitors,so it is a very promising new electrochemical energy storage devices.High-performance for lithium-ion capacitor is the key to match and balance the battery-type-material embedded with a slower reaction and the capacitance-type-electrode with rapid stripping absorption process.Therefore,design and preparation of excellent rate performance battery-type anode materials is the important to improve lithium-ion capacitor power density.In this paper,the design and preparation of core-shell structure Fe3O4@C and three-dimensional network structure of graphene@Fe3O4/C composites,researching their structure and performance of insert and abject lithium-ions,which respectively match activated carbon material to show high-performance for lithium-ion capacitor,and discuss the optimal about lithium-ion capacitor work voltage range and quality ratio of anode and cathode.Firstly,biomass chitosan as raw material used hydrothermal carbonization in situ in Fe2O3 nanoparticles surface with a layer of chitosan derived carbon,and after high temperature heat treatment to improve the electrical conductivity of the carbon layer,at the same time Fe2O3 reduced to Fe3O4.Core-shell structure of Fe3O4@C composite was obtained.In situ covering biomass derived carbon ways is effective utilization of biological resources,inhibiting the particles grow up,improving electrical conductivity,and providig the intercalat-Li+ volume expansion during the process of buffer space.The preparation of core-shell structure Fe3O4@C composites exhibite excellent electrochemical performance,in the current density of 0.1 A/g with the specific capacity of 1116.1 mAh/g.Applied Fe3O4@C composites to the lithium-ion capacitor is obtained the high energy facility with the energy density of 110.1 Wh/kg.This paper further used carbon coated Fe3O4 nanoparticles uniformly loading on the surface of graphene,so the preparation of a three-dimensional network structure of Fe3O4/C@rGO composite materials were obtained.Graphene layers overlap each other,not only providing three-dimensional conductive network efficiently,and also effectively bufferring the volume expansion of the Fe3O4 nanoparticles in the process of lithium storage.The preparation of a three-dimensional network structure of Fe3O4/C@rGO composite showed excellent electrochemical performance,in 0.2 A/g current density with the specific capacity of 1241 mAh/g.Applied it to the lithium-ion capacitor is obtained in the energy density of more than 110 Wh/kg.This paper research the design and preparation of high-performance lithium-ion capacitor has important guiding significance.