Ultra-High Resolution Electrocapillarity Correlates Interfacial Structure and Battery Performance

The electrode-electrolyte interface governs the kinetics and reversibility of all electrochemical processes. However, its structure and key properties often remain in theoretical models and simulations, due to the long-standing absence of direct experimental techniques. Electrocapillarity is a classical technique that directly probes the interfacial structure via interfacial tension measurement. In this work, we modernized this technique with ultra-high resolution and sampling rate. Its application on Zn-battery electrolytes reveals a unique local Zn²⁺concentration distribution and interfacial structure constructed by Cl^–specific adsorption, which favors<b> </b>fast Zn deposition/stripping kinetics. The renaissance of electrocapillarity allows us to directly correlate the electron transfer kinetics and zinc battery performance with interfacial structure, which will serve as a universal tool to guide the design of better electrolytes.