Mitigating Contact Loss in Li₆PS₅Cl‐Based Solid‐State Batteries Using a Thin Cationic Polymer Coating on NCM

Thiophosphate-based solid-state batteries (SSBs) with high-nickel ternary cathode materials such as LiNi0.83Co0.11Mn0.06O2 (NCM) represent a promising next-generation energy storage technology due to their expected high specific discharge capacity and improved safety. However, rapid fading caused by contact loss through interphase crack formation during cell cycling is significant problem hindering stable SSB high-energy-density applications. In this work, uniform coating of poly((4-vinyl benzyl)trimethylammonium bis(trifluoromethanesulfonylimide)) (PVBTA-TFSI) on NCM obtained via spray-drying process. This exceptionally thin cationic polymer only 2–4 nm thickness helps stabilize the interface between Li6PS5Cl solid electrolyte (SE). Electrochemical tests confirm improvement in long-term performance active mass utilization compared uncoated NCM. addition, effectively suppresses degradation NCM/SE interface, particularly oxygenated species, reduces extent particle cracking. Overall, these results highlight new approach mitigate using for SSBs.