Localizing concentrated electrolyte in pore geometry for highly reversible aqueous Zn metal batteries

Abstract Rechargeable aqueous Zn metal batteries are promising for large-scale renewable energy storage. However, the aqueous Zn metal battery chemistry encounters severe irreversibility issues, as manifested by the non-uniform metallic Zn plating and undesired side-reactions of corrosion. Herein, we report a highly-reversible aqueous Zn metal anode with accurately controlled nanopore structure, by which the space charge distribution could be regulated and interface-localized concentrated electrolyte was enabled. Consequently, the nanoporous Zn (npZn) electrode exhibited high electrochemical reversibility for 750 h under the measurement with a combination of electrochemically Zn stripping/plating cycling (1 mA cm−2 and 1 mAh cm−2 for 25 cycles) and resting (50 h), and looping. Moreover, a npZn||NaVO3 cell exhibited a high capacity of 200 mAh g−1 and a long lifespan with considerable capacity retention (76% for 1500 cycles), and high reversibility (Coulombic efficiency of 99.8%), which was more stable than the counterpart with pristine Zn anode (short-circuit after 600 cycles).