A high-energy-density aqueous dual-ion anode-free Zn battery under cryogenic conditions

Achieving high energy density under cryogenic conditions is essential for aqueous Zn batteries to work in extreme environments. Anode-free configuration can improve energy densities of Zn batteries close to their theoretical limit. However, the intrinsic low energy density and complex preparation of the current Zn-rich cathodes severely limit the prospect of aqueous anode-free Zn batteries (AFZBs). Herein, AFZBs with dual-ion chemistry (DAFZBs) are designed to conquer this limitation via replacing Zn-rich cathode by commercially available electrode materials. It works with reversible insertion/extraction of Li+ or Na+ at cathode and reversible Zn plating/striping at anode. Due to the higher reversible specific capacity and the higher potential derived from the larger Gibbs free energy (Delta Gcathode) of the Li+ or Na+ intercalation into the cathode host than that of Zn2+, the energy densities of the DAFZBs are boosted. Specifically, the LiMn2O4 (LMO)||Cu and Na3V2(PO4)3 (NVP)||Cu batteries achieved high discharge voltage of 1.8 and 1.4 V, along with high energy densities of 123.4 and 168.1 Wh kgcathode+anode degrees C, the LMO||Cu battery exhibits record-high energy densities of 172.1 Wh kgcathode+anode through the energy density limit of traditional AFZBs at cryogenic conditions by employing dual-ion chemistry.