A cationic polymeric interface enabling dendrite-free and highly stable aqueous Zn-metal batteries

Abstract

Recently, aqueous rechargeable zinc-ion batteries (AZIBs) have attracted much attention owing to their low cost and intrinsic safety. However, the reversibility of AZIBs is limited by dendrite growth on the Zn anode, which leads to low Coulombic efficiency and potential short circuit during cycling. Herein, we develop a new strategy using electrostatic shielding to enable a highly reversible Zn anode. Specifically, a cationic polymeric ionic liquid (PIL) coating layer with a strong positive charge evens out the charge distribution on the surface of the Zn electrode, enabling uniform stripping and deposition of Zn. As a result, a symmetric Zn–Zn cell can sustain stripping-plating for over 2000 h at 1 mA cm−2 with a capacity limit of 1 mAh cm−2, far exceeding the performance of bare Zn electrode. A highly reversible Zn stripping-plating on Cu substrate is also achieved with an average coulombic efficiency of 99.5% over 1100 cycles. PILZ layer can even allow a uniform Zn deposition of up to 30 μm thick, allowing large utilization of the Zn foil. Moreover, the coating layer enables the stable cycling of a MnO2–Zn full cell with a high areal capacity of 1 mAh cm−2.