Stress‐Mediated Dynamic Li Plating in Practical Li Metal Pouch Cells

Abstract The performance of rechargeable lithium (Li) metal batteries significantly depends on the behavior of Li plating/stripping at the anode, a process that is profoundly impacted by stack pressure. A schematic representation that elucidates the Li plating process under varying states of charge (SOCs) and initially imposed pressure is presented. This diagram illuminates the fundamental interplay between the structure of Li deposits (including density, morphology, and homogeneity) and variations in stress (ΔP)/strain (ΔL) (ΔP = k ΔL in the operando spatial stress measurement setup, where k denotes the thickness‐sensitive coefficient). This study uncovers an inherent self‐densification Li plating behavior that is driven by dynamic stress during charging. This mechanism results in an escalating Li density from the base to the apex of the electrode. A soft, elastic stress mediator is engineered to manipulate stress evolution by reducing the k value, consequently lowering ΔP and internal pressure of the cell during cycling. Prototype 1.4 Ah LiNi 0.95 Mn 0.03 Co 0.02 O 2 (NMC) ||Cu pouch cells achieve a superior cell‐level energy density of 537 Wh kg −1 and retain 76% capacity retention after 100 cycles at 0.2 C, in contrast to disappointing soft short‐circuit predicament and 68% capacity retention by the 70th cycle for the cell without stress mediator.