Realizing high-areal-capacity anode-free Zn metal batteries

Anode-free configuration holds great promise to extend the energy density of Zn metal batteries to its theoretical limit. However, current anode-free Zn metal batteries (AFZMBs) are limited to low areal capacities (< 0.5 mAh cm−2) due to the unsatisfied reversibility of Zn anode at high areal capacities, which greatly impeded the development of AFZMBs' energy density and their potential practical applications. Here, a high-areal-capacity AFZMB is realized by introducing a crowding agent, isosorbide dimethyl ether (IDE), into conventional aqueous electrolyte. IDE not only lowers water reactivity and freezing point of the electrolyte, but also guides epitaxial Zn plating at high areal capacity. Moreover, the unique stereoscopic IDE facilitates to form a stable anion-derived ZnF2-rich solid electrolyte interphase (SEI) on the in situ deposited Zn anode, achieving a high Coulombic efficiency of 99.95 % for Zn||Cu half-batteries. Impressively, the Cu||ZnNVO full batteries deliver extra-high energy density at high areal capacity of 222.4 Wh kg−1 (3 mAh cm−2) at 25 °C and 156.1 Wh kg−1 (1.7 mAh cm−2) at −30 °C (based on the mass of total active materials), as well as ultralong cycle life, exhibiting cutting-edge performances among the reported AFZMBs. This work may push forward the development of promising practical application of AFZMBs.