Mechanistic understanding of inhomogeneous lithium-plating behavior in large-format lithium-ion batteries during fast charging

Inhomogeneous lithium-plating in large-format lithium-ion batteries during fast charging critically degrades safety performance and cycle life.‌ This study systematically investigates this behavior under room-temperature fast-charging conditions.‌ First, an electrochemical-thermal coupled model incorporating lithium plating/stripping dynamics is developed and validated across temperatures (0–25 °C) and C-rates (1/6C-2C).‌ Using this model, we elucidate the inhomogeneous electrochemical and thermal characteristics, revealing significant heterogeneity during 2C charging at 25 °C: normalized solid-phase surface Li-ion concentration differences reach 0.21 (anode) and 0.34 (cathode), while uneven current density induces thermal variations with a maximum temperature deviation of 3.86 °C (dominated by ohmic heating). Further analysis of lithium-plating evolution shows initial nucleation at the edges due to higher Li-ion concentration, which lowers the local equilibrium potential, driving the anode potential below 0 V (vs. Li/Li⁺). As charging progresses, current density shifts to the central region, accelerating plating kinetics and ultimately resulting in greater Li deposition in the center than at the edges—experimentally confirmed by gas chromatography. Notably, reversible lithium fully strips before constant-voltage charging ends, avoiding the characteristic relaxation voltage differential curve minimum. These findings provide critical insights for mitigating inhomogeneous lithium-plating in large-format battery designs.