Study On Preparation And Energy Storage Behavior Of Nickel-based Perovskite-type Hybrid Supercapacitor Electrode Materials

Hybrid supercapacitors are composite components that have more enhanced characteristics than electric double layer capacitors and pseudocapacitors.It has the same characteristics as other capacitors,such as green environmental protection,fast charge and discharge,and stable cycling,so it has attracted the attention of many scholars.The electrochemical performance of supercapacitors is determined by the electrode materials.Improving the performance of hybrid supercapacitors requires the design and development of electrode materials.As one of the important components of transition metal oxide materials,NiO has been extensively studied because of its rich redox activity and high pseudocapacitance behavior.However,similar to other transition metal oxides,low utilization of electrode materials and poor conductivity hinder their practical application.In recent years,perovskite-type oxides with ABO₃structure have been intensively studied due to structural stability.La_0.7Sr_0.3CoO_3-δand La Mn O_3-δas typical perovskite-type oxide materials possess significant electronic conductivity at room temperature.Porous nanofibers prepared by electrospinning have become potential electrode materials for hybrid supercapacitors due to their high electrical conductivity,large specific surface area and independence.In this paper,the La_0.7Sr_0.3CoO₃/NiO（LSC/NiO）composite nanofibers doped with Sr in the perovskite oxide La CoO₃ were prepared by the electrospinning method,and the A-site and B-sites of La Mn O₃ were prepared La_0.7Sr_0.3Co_0.1Mn_0.9O₃/NiO（LSCM/NiO）composite nanofibers doped with Sr and Co elements respectively.The two are used as electrode materials to study their structure,morphology,chemical composition and electrochemical performance.The main research results are as follows:（1）The A-site doped La_0.7Sr_0.3CoO₃/NiO nanotube fibers all have porous morphology.When the molar ratio of LSC to NiO is 1:2,the pores are neatly arranged and uniformly distributed to"twist-like"structure.Correspondingly,in the electrochemical performance test of LSC/NiO（1:2）,the electrochemical performance result is the best.When the current density is 1 A g^-1,the specific capacity reaches319 C g^-1,while the specific capacity of a single LSC and NiO is only 1/7 and 1/2 of that of the LSC/NiO composite.These excellent electrochemical properties benefit from the porosity of the LSC/NiO composite nanomaterials.The abundant pores can give the electrode material stronger adhesion and maintain a stable structure.At the same time,the porous material improves the ion diffusion rate in the electrolyte and ensures the fluency of the electrochemical reaction.More importantly,the synergy between LSC and NiO has laid the foundation for the excellent performance of LSC/NiO.（2）The dual-doped La_0.7Sr_0.3Co_0.1Mn_0.9O₃/NiO nanorod fiber has a specific capacity of 686.1 C g^-1 at a current density of 1 A g^-1,which is higher than the unit doped LSC/NiO.The single-electrode LSCM/NiO maintained a cycle stability of 96.3%after 5 000 cycles,which proved that the dual-doped composite nanofibers provide more active sites and stable morphology for electrochemical reactions.This can be attributed to the two-site doping of the ABO₃ type that can provide more oxygen vacancies to the perovskite oxide,and the increase in oxygen vacancies provides more electron transport channels for electrons.（3）In order to study whether the composite electrode materials prepared are suitable for practical applications,this paper uses the prepared nanomaterials as the positive electrode and commercial AC as the negative electrode to assemble a hybrid supercapacitor.The potential window of LSC/NiO and LSCM/NiO can reach 1.5 V.When the current density is 1 A g^-1,the specific capacity of LSC/NiO//AC reaches166 C g^-1,while the specific capacity of LSCM/NiO//AC is 166 C g^-1.It shows a specific capacity of 209 C g^-1.After 10 000 cycles,the retention rate of LSC/NiO//AC was 93.7%,and the capacity retention rate of LSCM/NiO//AC was 96.3%.It can be seen that doping elements in the ABO₃ type can improve the structural stability of the oxide.The nanofibers prepared by electrospinning technology have porous characteristics,and after being further compounded with high specific capacitance transition metal oxide materials,the conductivity and specific capacity of the electrode materials can be improved.It can be concluded that the porous composite nanofibers prepared in this paper have the potential to become the next generation of excellent hybrid supercapacitor electrode materials.（4）The electrode material prepared in this paper is controlled by Faraday reaction and capacitive energy storage.The coexistence and transformation of these two energy storage mechanisms have great advantages in improving the specific capacity and cycle life of electrode materials.The results of the related electrochemical tests confirm that the composite material of transition metal oxide and perovskite oxide with high specific capacitance designed in this paper is a kind of electrode material with research value for commercial applications.