High-energy, long-life Ni-rich cathode materials with columnar structures for all-solid-state batteries

All-solid-state batteries (ASSBs) comprising Ni-rich layered cathode active materials (CAMs) and sulfide solid electrolytes are promising candidates for next-generation batteries with high energy densities and safety. However, severe capacity fading occurs due to surface degradation at the CAM-electrolyte interface and severe lattice volume changes in the CAM, resulting in inner-particle isolation and detachment of the CAM from the electrolyte. Here we quantified the capacity fading factors of Ni-rich Li[NixCoyAl1-x-y]O2 composite ASSB cathodes as functions of Ni content. Surface degradation at the CAM-electrolyte interface was found to be the main cause of capacity fading in a CAM with 80% Ni content, whereas inner-particle isolation and detachment of the CAM from the electrolyte play a substantial role as the Ni content increases to 85% or more. On the basis of the comprehensive understanding of these mechanisms in ASSBs, high-performance Ni-rich CAMs with columnar structures were developed through surface and morphology modification.