Deciphering dynamic solid-liquid interphase for energetic high-mass-loading energy storage

Abstract

Aqueous pseudocapacitive storage has shown promise in future energy techniques, but it suffers from the single reaction pathway and mechanism that restrains the performance breakthrough, especially under commercially high-mass-loading conditions. Herein, with MnO2 as the demo, we tailored a reversible pseudocapacitive-type electrode/electrolyte interphase (PEI) via refining the cationic environment, which for the first breaks the limitation of MnO2 to unlock an energetic dual-ion storage mechanism. Theoretical calculations demonstrate that the engineered dynamic PEI elevates the removal energy of active Mn species to stabilize dual-cations storage, and more importantly, provides highly available MnO2/PEI heterointerface spaces to accommodate more charges. We unveil that the exceptional heterointerface region with considerable charge redistribution enables a significantly reduced ion-migration energy barrier than that of the pure MnO2 interlayer, contributing to fast “multi-processing” storage of dual carriers. As a proof-of-concept, the tailored mechanism enables robust stability with 92% capacitance retention after 25000 cycles. Besides, an appealing areal capacitance of 11.1 F cm-2 can be demonstrated under a high mass loading of 27.4 mg cm-2. Our findings signify a paradigm transformation of aqueous pseudocapacitive chemistry and offer insights into dynamic microenvironment regulation for building advanced energy storage devices.