Recent advances and future perspectives of Ruddlesden–Popper perovskite oxides electrolytes for all-solid-state batteries

All-solid-state batteries equipped with solid-state electrolytes(SSEs)havegained significant interest due to their enhanced safety,energy density,andlongevity in comparison to traditional liquid organic electrolyte-based batteries.However,many SSEs,such as sulfides and hydrides,are highly sensitiveto water,limiting their practical use.As one class of important perovskites,theRuddlesden–Popper perovskite oxides(RPPOs),show great promise as SSEsdue to their exceptional stability,particularly in terms of water resistance.Inthis review,the crystal structure and synthesis methods of RPPOs SSEs are firstintroduced in brief.Subsequently,the mechanisms of ion transportation,including oxygen anions and lithium-ions,and the relevant strategies forenhancing their ionic conductivity are described in detail.Additionally,theprogress made in developing flexible RPPOs SSEs,which are critical for flexibleand wearable electronic devices,has also been summarized.Furthermore,thekey challenges and prospects for exploring and developing RPPOs SSEs in allsolid-state batteries are suggested.This review presents in detail the synthesismethods,the ion transportation mechanism,and strategies to enhance theroom temperature ionic conductivity of RPPOs SSEs,providing valuableinsights on enhancing their ionic conductivity and thus for their practicalapplication in solid-state batteries.