Regulating Interfacial Electron Density of Carbon for Stable and High‐Performance Batteries

ABSTRACT

Conductive carbon is widely used in battery systems as a conductive additive and structural scaffold, yet its role in parasitic reactions remains poorly understood. Contrary to the common assumption of electrochemical inertness, growing evidence shows that carbon actively governs interfacial reactions, leading to electrolyte decomposition, hydrogen evolution, and structural degradation that limit battery stability and lifetime. Here, we provide an electronic‐structure‐based perspective to elucidate and regulate carbon‐induced parasitic reactions across diverse battery chemistries. We demonstrate that these seemingly distinct degradation phenomena originate from a common electronic origin defined by interfacial electron density and Fermi‐level alignment. Carbon operates within a finite electronic stability window, where electron oversupply drives reductive side reactions, while electron depletion induces oxidative degradation. Based on this understanding, we outline design strategies to control interfacial electron density, including Fermi‐level engineering, defect‐state optimization, and decoupling bulk electron transport from interfacial electron injection. These strategies enable suppression of parasitic reactions and provide pathways to improve cycling stability, energy efficiency, and durability in advanced battery systems. This review presents a unified electronic framework for understanding and controlling carbon‐induced degradation and offers practical guidance for the rational design of electronically stable carbon materials for next‐generation energy storage.