Alleviating kinetical delamination induced by localized cathode contact via electrochemo-mechanical modeling in all-solid-state batteries

Abstract

While all-solid-state batteries (ASSBs) offer promise for high safety and power density due to the Li superionic solid electrolytes (SEs), they suffer from mechanical delamination at cathode-SE interfaces, hindering reliable cycle life. Herein, we elucidate the principles underlying kinetics-induced mechanical delamination in high-nickel layered oxide cathodes by comparing electrodes in different cathode contact coverages at various current densities. An electrochemo-mechanical model demonstrates that low and localized contact coverage induces a kinetics-driven Li concentration gradient and relatively rapid contraction at the narrow contact area, leading to accelerated delamination of each particle. This phenomenon is supported by the reduction of coverages in electrodes after cycling. By increasing the size ratio of active materials to SEs, the electrodes with high and uniform coverage exhibited extended cyclability, retaining 79.1% after 1,000 cycles at a 5C rate. This study highlights the effect of uniform contact with high coverage in mechanical delamination for achieving high-performance ASSBs.