Accelerated capacity fade in high-voltage Li-ion batteries is attributed to crosstalk between the positive and negative electrodes. The main mechanism occurs when transition metals dissolve from the active material of the cathode, travel to the negative electrode, and disrupt the formation, growth, and performance of the solid-electrolyte interphase (SEI), leading to unmitigated capacity fade. In full-cell studies the effects of electrolyte decomposition and metal dissolution on battery lifetime and coulombic efficiency are well-documented, however the precise nature of crosstalk species and the mechanism of capacity fade remain to be understood. Here we present two applications of our generator-collector approach to understanding battery crosstalk. First, we employ rotating-ring disk electrode (RRDE) voltammetry to study the effects of metal dissolution from LNMO (LiNi0.5Mn1.5O4) on SEI performance. By cycling an LNMO-coated glassy carbon disk to high operating potentials, we stimulate metal dissolution and collect these soluble species on the downstream ring electrode, which is cycling to low potentials to form and grow an SEI. The effects of metal contamination on SEI passivation are characterized via a redox mediator method and quantified using finite element simulations. We find that metal dissolution has a more profound impact on electronic than morphological SEI properties. In the second application, we demonstrate an improved method for performing generator-collector measurements on composite electrodes via the development of a microfluidic electrochemical cell. Our design incorporates commercial electrodes and electrolyte, and utilizes forced convection to isolate the upstream electrode from crosstalk species generated at the downstream electrode, thus deconvoluting the role of electrolyte oxidation and reduction on capacity fade. We demonstrate that our device can quickly detect crosstalk using commercial Li-ion battery components, thus expanding our abilities to electrochemically diagnose capacity fade.

Electrochemical characterization of crosstalk reactions in li-ion batteries

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.