Stable performance of an all-solid-state Li metal cell coupled with a high-voltage NCA cathode and ultra-high lithium content poly(ionic liquid)s-based polymer electrolyte

A poly(ionic liquid)s binder can provide stable performance of high-voltage composite cathodes based on lithium nickel cobalt aluminium oxide (LiNi${}_{0.8}$Co${}_{0.15}$Al${}_{0.05}$O${}_2$ or NCA), up to 4.5 V (vs. Li${}^{+}$/Li${}^0$) at 50 °C for an electrode with high areal capacity up to 1.6 mAh cm${}^{-2}$. A reversible capacity of more than 150 mAh g${}^{-1}$ in an all-solid-state device using a highly concentrated poly(ionic liquid)s-based composite polymer electrolyte is achieved with high-capacity retention on cycling. Characterization of the composite electrode and polymer electrolyte post-cycling using scanning electron microscopy confirms stable behaviour with only small volume changes evident. This report thus demonstrates these solid polymer electrolytes as promising for high energy density high-voltage all-solid-state lithium (Li) batteries.