Electrolyte-derived interphases control nonuniform charging in battery particle networks

This is the authors' abstract. We don't add key points for this paper.

In an ensemble of battery particles, dynamic interactions among individual particles give rise to emergent behavior like nonuniform charging. Yet, its origins have remained contested due to the challenge of directly measuring the current into each particle. Inspired by neuronal potential recordings in brain-computer interfaces, we present Multichannel Acquisition of Parallel-particle Level Electrochemistry (MAPLE) to map dynamic current distributions in real time. We demonstrate that asynchronous charging in layered oxide cathodes does not originate from bulk properties but instead results from a fluorinated cathode electrolyte interphase (CEI). This CEI forms upon electrolyte exposure before cycling and impedes Li + transport. Counterintuitively, intergranular cracking rescues these passivated particles by exposing pristine internal surfaces, whereas single-crystal particles without grain boundaries are more vulnerable to this Li + -impeding CEI.