Advances in Developing Inorganic Calcium Solid-State Electrolytes: A Minireview

The technology of lithium-ion batteries is reaching its limit of energy density and cost reduction in usage for electrochemical energy storage. As a promising long-term sustainable alternative to lithium-based technology, Ca-ion batteries (CIBs) coupled with metal anodes are increasingly gaining scientific attention. Ca solid-state electrolytes (SSEs) are key components for the development of CIBs. In this minireview, we summarize and discuss the most recent advances of inorganic Ca ionic conductors as potential SSE candidates. We focus on their SSE-relevant properties, including the Ca-ion conductivity, electrochemical stability, and ionic diffusion mechanisms, with the key challenges and future perspectives elucidated.