A novel method for mechanical battery abuse testing: Planetary mill calorimetric evaluation of all-solid-state battery materials and their safety

This work presents a novel quantitative calorimeter-mill methodology for ASSB materials that quantitatively measures energy release by combining ball milling with calorimetry and pressure monitoring during extreme mechanical activation. The method accounts for the mechanical milling contribution using an operational reference. Applied to a shredded cathode consisting of delithiated state of charge 100% (SOC 100) Li x Ni 0.83 Mn z Co 0.17-z O 2 (x < 1, z < 0.17) (NMC), Al current collector, binder and conductive carbon together with systematically chosen amounts of Li 6 PS 5 Cl representing different catholyte compositions, the method quantifies composition-dependent energy release and gas evolution under extreme mechanical abuse. The method revealed that a shredded, delithiated NMC cathode showed substantial reactivity (2799 ± 159 J/g (NMC) ) with significant gas evolution, while Li 6 PS 5 Cl electrolyte addition enhanced the energy release and reduced the required mechanical activation and the gas generation. The calorimeter-mill approach provides a quantitative framework for establishing worst-case energy boundaries and enabling early-stage safety decisions in battery material development.