Pyrrole as a multi-functional additive to concurrently stabilize Zn anode and cathode via interphase regulation towards advanced aqueous zinc-ion battery.

The advancement of aqueous zinc-ion batteries (AZIBs) is impeded by challenges encompassing cathodic and anodic aspects, such as limited capacity and dendrite formation, constraining their broader utilization. Herein, pyrrole, an economically viable and readily accessible compound, is proposed as a versatile electrolyte additive to address these challenges. Experiments and DFT calculations reveal that pyrrole and its derivatives preferentially adsorb onto zinc foil, facilitating the formation of a pyrrole-based solid electrolyte interphase (SEI), which effectively guides uniform Zn2+ deposition through strong attraction force and suppresses hydrogen evolution reactions and parasitic reactions. On the cathode side, the additive promotes the formation of a durable cathode electrolyte interphase (CEI) enriched with poly-pyrrole (Ppy) analogues. Such layer significantly contributes to extra capacity of both polyaniline (PANI) and MnO2 cathodes by leveraging the electrochemical reactivity of Ppy towards Zn2+ and improves their cyclic stability. Consequently, a dendrite-free Zn anode is realized with an extended cyclic lifespan surpassing 6000 h in Zn//Zn cell, coupled with an average Coulombic efficiency of 99.7 % in Cu//Zn cell. Moreover, the PANI//Zn and MnO2//Zn full cells demonstrate enhanced capacities along with improved cycling stability. This work provides a new additive strategy towards concurrent stabilization of cathode and Zn anode in AZIBs.