Lithium-ion batteries rely on particulate porous electrodes to realize the high performance, especially the fast-charging capability. To minimize the particle-wise reaction heterogeneities that may lead to local hot spots, deeper understandings of the reaction mechanisms that are coupled with material thermodynamics, yet at the mesoscale, i.e. hundreds of particles, have become an urgent need. Using practical graphite electrode as a mode system, we performed rigorous investigations by combining <i>operando</i> experiments and linear stability analysis. Our work reveals that the seemingly random reaction heterogeneities are actually controlled by the interplays between the non-equilibrium material thermodynamics and the electrochemical kinetics. During constant-current operations, there exist autonomous dynamic loops that determine the intra- and inter-particle phase transformation dynamics and thereby determine the true local current density. Unlike other phase-transforming porous electrodes, not all phase separation processes in graphite electrodes can be suppressed by high currents. Our results highlight the necessity to examine the concentration-dependent exchange current density for intercalation electrodes undergoing complex phase transformation processes. Incorporating nonequilibrium thermodynamics into classical electrochemical models and electroanalytical techniques will ensure self-consistent understandings of practical porous electrodes toward precision design and management.

Autonomous interplays between Phase Transformation Instabilities and Spatiotemporal Reaction Heterogeneities in Particulate Intercalation Electrodes

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ACS Fall 2022

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