Preparation Of NiCoV LDHs Electrode And Investigation On Properties Of Alkaline Zinc Ion Batteries

With the continuous development and progress of electrochemical energy storage system,water zn-ion battery（AZIBs）has become an ideal energy storage system promising to replace lithium ion battery.AZIBs have the advantages of high theoretical specific capacity(820 m Ah g^-1),excellent safety performance and cheap availability.In the actual application scenario,positive electrode material affect the specific capacity.In the process of electrochemical reaction,the rapid removal and embedding of ion in the positive electrode material will cause the structure of the positive electrode material to distort or even collapse,and some electrode materials will even dissolve in the electrolyte,which is the main reason for the specific capacity attenuation of the electrode material.Therefore,in the current research of AZBIs,the main barrier to be broken is to develop positive electrode materials with high capacity and stability.Among many cathode materials,hydrotalcite（LDHs）cathode materials have attracted much attention because of their highly controllable main laminae and interlaminae anions.Therefore,the main research content of this paper is as follows:（1）NiCl₂·（H₂O）₆,CoCl₂·（H₂O）₆and VCl₃were used as reaction materials to prepare NiCoV LDHs anode materials with different ratios of Ni,Co and V by a simple one-step coprecipitation method.After the morphology,structure and electrochemical performance were tested and characterized,the optimal ratio of Ni,Co and V is 3:3:1,and the NCV3anode material has small layer size and obvious layer spacing.Under the current density of 1 A g^-1and 15 A g^-1,it has the discharge specific capacity of 153.92 m Ah g^-1and 67.93m Ah g^-1,set the current density of 5 A g^-1,after 1000 cycles of the battery,the discharge capacity decreased from 94.50 m Ah g^-1to 75.50 m Ah g^-1,and the capacity retention rate reached 79.89%.（2）On the basis of determining the optimal ratio of Ni,Co,V,this paper further optimizes the interlayer anions of LDHs.Anions NO₃²⁺,Zn O₂²⁺,PAM and PO₄³⁺were inserted into NiCoV LDHs cathode materials.Electrochemical performance of NiCoV LDHs cathode materials intercalated with different anions was tested.It is found that PO₄³⁺intercalated NiCoV LDHs anode material has the best electrochemical performance.Under the current density of 1 A g^-1and 15 A g^-1,it has the discharge specific capacity of118.63 m Ah g^-1,and 75.83 m Ah g^-1,set the current density of 5 A g^-1,after 1000 cycles of the battery,the specific discharge capacity decreased from 102.79 m Ah g^-1to 86.26 m Ah g^-1,and the capacity retention rate reached 83.91%.（3）By changing the addition amount of Na₃PO₄,the electrochemical performance test showed that NiCoV LDHs anode material had the best electrochemical performance when the addition amount of Na₃PO₄was 4.5 g.Under the current density of 1 A g^-1and15 A g^-1,it has the discharge specific capacity of 139.14 m Ah g^-1,and 89.78 m Ah g^-1,set the current density of 5 A g^-1,after 1000 cycles of the battery,the specific discharge capacity decreased from 106.08 m Ah g^-1to 95.52 m Ah g^-1,and the capacity retention rate was as high as 90.05%.