The Preparation And Energy Storage Characteristics Based On Bimetallic Perovskite Fluorides Electrode Materials

With the lack of non-renewable energy and the inconsistency between the rapid development of electronic information and new energy vehicles,finding green and efficient energy storage system has always been the focus of people's attention,and is also a hot topic of current scientific research.Lithium-ion batteries and supercapacitors are currently the most widely used and efficient energy storage devices.Because of the poor stability and low rate performance of electrode materials based on traditional transition metals,their fields are relatively single,and these greatly limit them wide application.Therefore,it is necessary to develop new electrode materials and apply them in different energy storage systems to meet the requirements of efficient energy storage.In this paper,two different types of electrode materials based on perovskite fluoride were synthesized and applied to supercapacitors,organic lithium-ion energy storage systems including lithium-ion batteries,lithium-ion capacitors and dual-ion batteries.respectively.The metal-fluorine bond high stability in perovskite and the synergistic effect between bimetals are used to enhance the electrochemical performance of these materials.The electrochemical performance test of the material is combined with a number of physical characterizations to conduct a preliminary study on the energy storage mechanism.The main contents are as follows:1.The bimetallic perovskite fluoride K-Co-Mn-F with different cobalt and manganese ratios was prepared by solvothermal method?Co:Mn=1:0,12:1,6:1,3:1,1:1,1:3,0:1?.K-Co-Mn-F?Co:Mn=6:1?electrode material exhibits a relatively large specific capacity(113 C g^-1/1 A g^-1)when performing single-electrode tests,excellent specific capacity retention(88.5%/1-16 A g^-1),and excellent cycle stability(118%/5000/8 A g^-1).K-Co-Mn-F?Co:Mn=1:0,0:1,6:1?as the positive electrode and the activated carbon?AC?negative electrode constitute an asymmetric supercapacitor,respectively,which AC//K-Co-Mn-F?Co:Mn=6:1?exhibits excellent electrochemical performance with energy density and power density(8 Wh kg^-1/0.14 kW kg^-1).And it has a capacity retention rate of up to 90%after 10000cycles at 5A g^-1 current density.2.Na-Ni-Co-F,a bimetallic perovskite fluoride with different nickel and cobalt ratios,was prepared by solvothermal method?Ni:Co=1:0,3:1,1:1,1:3,0:1?).The results of the half-cell experiment show that Na-Ni-Co-F?Ni:Co=1:1?exhibits the optimal electrochemical performance.A number of physical characterizations were carried out to determine that the molecular formula was Na_0.85Ni_0.45Co_0.55F_3.56.It is obvious that there are Na vacancies in the sample.It is also proved that surface conversion and insertion hybrid mechanism occur during charging and discharging.Then it is used as new anode electrode material,and five types of cathodes including activated carbon?AC?,AC+LiFePO₄?LFP?,graphite?KS6?,KS6+LFP and LFP were introduced to construct the NNCF//AC and NNCF//AC+LFP LICs,NNCF//KS6and NNCF//KS6+LFP Li-DIBs and NNCF//LFP LIB.Among them NNCF//AC+LFP LICs exhibits energy density and power density(132.3 Wh kg^-1/0.6 kW kg^-1),and circulates 2000 cycles at a current density of 5 A g^-1 to maintain 79%.The dual-ion battery NNCF//KS6+LFP exhibits an energy density and power density(161.3 Wh kg^-1/0.6 kW kg^-1),and the capacity of the cycle is maintained at 74%at a current density of 2 A g^-1;The NNCF//LFP LIB exhibited an energy density and power density(196.2 Wh kg^-1/0.8 kW kg^-1),and the specific capacity of the cycle was maintained at 63%at a current density of 3 A g^-1 in circulates 2000 cycles.