Recent progress in rechargeable calcium-ion batteries for high-efficiency energy storage

Benefiting from cost-effectiveness, high volumetric/gravimetric capacity and low reduction potential of Ca metal anode, rechargeable calcium-ion batteries (CIBs) are promising alternatives for use as post-lithium-ion batteries. Nevertheless, their practical applications are still restricted by the absence of appropriate electrode materials, the sluggish kinetics of Ca2+ intercalation/de-intercalation and incompatibilities between electrodes and electrolytes. In this review, the most recent advances in CIBs, including cathode and anode materials as well as the electrolytes, are systematically summarized and discussed. The relationship between the structures of electrode materials and their reaction mechanisms is comprehensively introduced. Moreover, the design strategies of electrode materials and suitable electrolytes are also elaborated to improve the energy density and enlarge the cycle life of CIBs. This review will provide comprehensive knowledge of Ca-based energy storage technology and guidelines for exploring new electrode materials and electrolytes for rechargeable calcium batteries.