Restoring Lost Active Material in Lithium-Ion Batteries via Low-Energy Dynamic Planar Compression

Mechanical abuse studies on lithium-ion batteries predominantly focus on localized, destructive loadings that trigger thermal runaway, leaving non-destructive planar dynamic stress and its long-term electrochemical degradation mechanisms under-explored. This study investigates the impact of dynamic, in-plane uniaxial compression on the long-term performance and degradation pathways of 1 Ah LCO-graphite pouch cells. Pre-aged cells (50 cycles) were subjected to flat-headed drop-weight impacts across a range of low energies (3, 5, 7, and 10 J) to isolate uniform planar compression while avoiding shear-driven separator rupture or internal short circuits. Post-impact cells were evaluated across 500 additional cycles using Hybrid Pulse Power Characterization, Incremental Capacity Analysis, and Scanning Electron Microscopy post-mortem imaging. Despite experiencing physical stress, dynamic impact did not compromise cell safety or alter long-term State of Health degradation trajectories. Instead, post-impact characterization revealed an immediate capacity rejuvenation coupled with an average reduction in ohmic resistance (R0) of 4.91±4.01 mΩ and a decrease in dynamic characteristic resistance (R1). ICA profiles demonstrated an increase in differential capacity peak heights post-impact, signaling a partial recovery of loss of active material. SEM analysis corroborated these findings, revealing inter-particular cracking of the solid electrolyte interphase on the anode and compaction of secondary cathode particles, which re-established conductive contacts in isolated electrode regions. These results demonstrate that uniform planar compression is not inherently catastrophic and can temporarily enhance performance by restoring active material networks, offering critical insights for second-life battery assessment and predictive mechanical abuse modeling.