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Underpotential lithium plating on graphite anodes caused by temperature heterogeneity

Significance Metallic lithium plating on the graphite anode is a predominant cause for capacity decays during the fast charging of lithium-ion batteries. This work studies the lithium-plating phenomenon in a previously neglected thermodynamic perspective, taking into account practical temperature distributions within batteries. We show that elevated temperatures could enhance the equilibrium potential of Li0/Li+, making local lithium plating more thermodynamically favorable. Furthermore, lithium-plating patterns are correlated with temperature heterogeneities, confirming the preferential lithium plating at high-temperature regions due to both kinetic and thermodynamic origins. These findings provide possible explanations of the heterogeneous lithium-plating morphology, deepen the understandings on the lithium plating phenomenon, and will guide future strategies to realize the extreme fast charging of lithium-ion batteries. Rechargeability and operational safety of commercial lithium (Li)-ion batteries demand further improvement. Plating of metallic Li on graphite anodes is a critical reason for Li-ion battery capacity decay and short circuit. It is generally believed that Li plating is caused by the slow kinetics of graphite intercalation, but in this paper, we demonstrate that thermodynamics also serves a crucial role. We show that a nonuniform temperature distribution within the battery can make local plating of Li above 0 V vs. Li0/Li+ (room temperature) thermodynamically favorable. This phenomenon is caused by temperature-dependent shifts of the equilibrium potential of Li0/Li+. Supported by simulation results, we confirm the likelihood of this failure mechanism during commercial Li-ion battery operation, including both slow and fast charging conditions. This work furthers the understanding of nonuniform Li plating and will inspire future studies to prolong the cycling lifetime of Li-ion batteries.