Unravelling the deterministic effect of the solid-state diffusion energy barrier for charge carrier on the self-discharge of supercapacitors

TL;DR

This paper investigates how the solid-state diffusion energy barrier influences self-discharge in supercapacitors, revealing its exponential effect and providing insights for better suppression strategies.

Contribution

It demonstrates the deterministic role of the solid-state diffusion energy barrier in supercapacitor self-discharge using conjugately configured devices with different phases.

Findings

Diffusion barrier affects self-discharge exponentially.

Solid-state diffusion energy barrier and extrinsic effects jointly influence self-discharge.

Materials with various diffusion barriers can be integrated to study their effects.

Abstract

The further development of fast electrochemical devices is hindered by self-discharge. Current strategies for suppressing self-discharge are mainly focused on the extrinsic and general mechanisms including faradaic reactions, charge redistribution, and ohmic leakage. However, the self-discharge process is still severe for conventional supercapacitors. Herein, we unravel the deterministic effect of solid-state diffusion energy barrier by constructing conjugately configured supercapacitors based on pairs of pre-lithiated niobium oxides with similar intercalation pseudocapacitive process but different phases. This device works with a single type of charge carrier while materials with various diffusion barriers can be implanted, thus serving as an ideal platform to illustrate the influence of the diffusion barrier. The results show that the comprehensive effect of solid-state diffusion energy barrier and extrinsic effects drives the self-discharge process. Noteworthy, the diffusion barrier presents with an exponential form, which governs the self-discharge of supercapacitors. This work is expected to unravel the deterministic effect of the solid-state diffusion energy barrier and provide a general guidance for suppressing self-discharge for supercapacitors.