From understanding to control: Unifying mechanistic insights and interface engineering in energy storage through advanced characterization

Electrolyte-electrode interfaces (EEIs) critically shape the performance, stability, and lifetime of energy storage systems, yet their buried complexity in structure, chemistry, and kinetics remains challenging to decode. This review synthesizes recent advances enabled by cryogenic electron microscopy, operando spectroscopy, and 3D tomography, which have uncovered interfacial heterogeneity, chemical evolution, and non-classical charge-transfer pathways. These findings revise static interphase models and explain discrepancies across systems once thought to be mechanistically similar. We highlight how integrated, multiscale diagnostics can resolve these differences and inform design. Building on this foundation, we examine emerging engineering strategies, including electrolyte reformulation, surface reconstruction, and artificial interphase design, that target specific interfacial failure modes. By bridging mechanism, measurement, and materials design, this review offers a road map for decoding and directing EEI behavior across diverse chemistries, from lithium-ion and solid-state batteries to supercapacitors, guiding next-generation energy devices toward greater reliability, efficiency, and control.