Research On The Construction Of Conjugate Supercapacitors Based On Embedded Pseudocapacitive Materials And Their Self-discharge Suppressio

Self-discharge is a common problem faced by electrochemical energy storage devices,especially in supercapacitors.Up to now,the strategies for suppressing self-discharge are mainly focused on modifying the individual components of supercapacitors,such as modifying the surface properties of electrode materials,synthesizing viscous electrolytes that can suppress carrier diffusion,and designing separators with selectively permeable structures.However,the effectiveness of material modification is limited due to a lack of matching in the overall structure.In recent years,the discovery of intercalation pseudocapacitive materials has provided a new method for designing and preparing supercapacitors with unconventional configurations.This article focuses on the influence of macroscopic configurations on the self-discharge of supercapacitors,using the unique energy storage mechanism of intercalation pseudocapacitive materials.This article proposed a method for preparing a supercapacitor with a conjugated configuration.By coupling a pair of pre-lithiated niobium oxide electrodes as the positive and negative electrodes,the reversible shuttle of lithium ions between two identical electrodes occurs during the charge and discharge process.Using the intercalation energy storage mechanism of niobium oxide,the supercapacitor with a conjugated configuration(Li_xNb₂O₅ vs.Li_2-xNb₂O₅)was successfully constructed.Theoretical calculations and experimental results show that the conjugated configuration can maximize the symmetry of the supercapacitor and reduce self-discharge caused by unstable asymmetric reactions.The voltage retention rate of the conjugated configuration supercapacitor(Li_xNb₂O₅ vs.Li_2-xNb₂O₅)is 10.7 times higher than that of the double-layer capacitor（AC vs.AC）,proving that the macroscopic conjugation can enhance the stability of the supercapacitor.With the help of the conjugated configuration,the characteristics of single carrier diffusion in the reaction process and the electrode/electrolyte interface of the supercapacitor are clarified.This further elucidates the unique self-discharge mechanism of the supercapacitor and the reasons for its significant self-discharge.In theory,the commonly accepted non-intrinsic mechanisms of Ohmic leakage,charge redistribution,and Faraday reactions have the same impact on all electrochemical energy storage devices.Considering the nature of self-discharge,this study believes that fast energy storage devices,including supercapacitors,have an intrinsic self-discharge mechanism related to active materials.Theoretical analysis and experimental verification demonstrate that self-discharge caused by intrinsic diffusion exhibits an exponential relationship with the solid-state diffusion barrier of the material.Materials with low diffusion barriers dominate the self-discharge process,while materials with high diffusion barriers are dominated by non-intrinsic interfacial effects.This understanding provides new insights for the design of electrochemical energy storage devices with low self-discharge.