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

Abstract

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[Ni_xCo_yAl_1−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.