(Invited) Understanding Chemical, Mechanical and Thermal Stability of NCA in Polymer Solid-State Batteries

The structural integrity and chemical stability of layered Ni-rich oxide cathode materials are influential factors that critically affect the performance and reliability of lithium batteries. Prolonged battery operation often involves repeated phase transitions, buildup of mechanical stresses, which could result in chemical and mechanical changes in cathodes. Chemo-thermo-mechanical interplay can cause performance degradation through various processes. Here we systematically investigate such complex chemomechanical and chemothermal interplays over a wide range of length scales within the hierarchically structured polymer solid-state batteries. This presentation will discuss our understanding of 1) The formation of mesoscale cracks and corresponding state of charge (SOC) inhomogeneity within secondary NCA particle cycled in solid polymer batteries 1 2) Thermal decomposition, fracture (intergranular and intragranular), and mesopores formation due to oxygen evolution in delithiated Li 0.30 NCA particles upon heating 2 3) long-term chemothermal stability of delithiated Li 0.30 NCA at relevant operating conditions of polymer solid-state batteries. 3 Our investigation provides a fundamental understanding of chemo-thermo-mechanical breakdown of the NCA in solid-state polymer batteries. Reference : 1. Besli, M. M. et al. Mesoscale Chemomechanical Interplay of the LiNi0.8Co0.15Al0.05O2 Cathode in Solid-State Polymer Batteries. Chem. Mater. 31 , 491–501 (2019). 2. Besli, M. M. et al. Thermally-driven mesopore formation and oxygen release in delithiated NCA cathode particles. J. Mater. Chem. A 7 , 12593–12603 (2019). 3. Besli, M. M. et al. Long-Term Chemothermal Stability of Delithiated NCA in Polymer Solid-State Batteries. J. Mater. Chem. A 11–13 (2019) doi:10.1039/c9ta11103d.