Bridging Zn2+/Ca2+‐Storage Chemistries by Hetero‐Solvation Electrolyte toward High‐Voltage Ca2+‐Based Hybrid Batteries

Abstract Earth‐rich Ca 2+ ions for energy storage can endow batteries with low‐cost and high‐energy merits, yet remain hampered by difficult Ca 2+ plating/stripping and (de)intercalation. Herein, by bridging Zn 2+ /Ca 2+ ‐storage chemistries, a high‐voltage and stable Ca 2+ ‐based hybrid battery (CHB) in a hetero‐solvation electrolyte (HSE) is initially achieved. With a [Ca 2+ (H 2 O)(acetonitrile)(CF 3 SO 3 ) − ] hetero‐solvation unit, the HSE not only allows a reversible in situ Zn stripping/plating to circumvent the low‐capacity/high‐potential limitation of non‐stripping/plating‐type anodes for Ca 2+ storage but also effectively overcomes kinetics‐sluggish Ca 2+ (de)intercalation usually occurring in conventional organic electrolytes. The acetonitrile‐rich water‐lean anode interface synergized by the electrostatic shielding effect of Ca 2 ⁺ ions plays a conducive role in facilitating highly reversible Zn stripping/plating. Moreover, the lubricating/shielding properties of water molecules in the hetero‐solvation unit effectively boost the Ca 2+ /Zn 2+ co‐insertion/extraction into/from the KNiMnPB/G cathode. Consequently, the HSE affords an endurable Zn stripping/plating over 1600 h, endows KNiMnPB/G//Zn battery with a high operating voltage of up to 1.85 V at 0.1 A g −1 , and demonstrates decent stability over 400 cycles at 1 A g −1 , outperforming most aqueous Ca 2+ ‐based batteries with non‐stripping/plating‐type anodes. This work sheds new light on the development of high‐voltage aqueous CHBs by bridging Zn 2+ /Ca 2+ ‐storage chemistries, which would boost to pursue other high‐energy multivalent‐ion batteries.