Yamin Zhang

Rechargeable aqueous zinc anodes have gained tremendous attention because of their merits of intrinsic safety, low cost, and high theoretical volumetric capacity (5854 mAh cm–3 for Zn metal). In aqueous electrolytes, zinc anodes suffer from severe dendritic metal deposition. The regulation of Zn by inducing Zn-alloying metals has been reported. However, the underlying mechanisms have remained elusive. Here, for the first time, we did a comprehensive analysis to elucidate the mechanisms for the seeded and nondendritic growth of Zn on alloy anodes. We achieved uniform Zn deposition by introducing a Zn-alloying and soluble metal, Ag, on Zn anodes. Due to a shift of thermodynamic potential and the spatial confinement, the Ag-modified Zn anode exhibited improved overall cycling performance compared with previous deep-cycle Zn anodes. Furthermore, the seeded Zn deposition was visualized in operando for the first time using an optical microscope. The alloy-seeding design principle here can potentially be applied to improve the rechargeability of other metal anodes.

Foldable potassium-ion batteries are achieved through flexible and free-standing SnS₂@C nanofibers.

Abstract As an alternative to lithium‐ion batteries, Zn‐based aqueous batteries feature nonflammable electrolytes, high theoretical energy density, and abundant materials. However, a deeply rechargeable Zn anode in lean electrolyte configuration is still lacking. Different from the solid‐to‐solid reaction mechanism in lithium‐ion batteries, Zn anodes in alkaline electrolytes go through a solid‐solute‐solid mechanism (Zn‐Zn(OH) 4 2− ‐ZnO), which introduces two problems. First, discharge product ZnO on the surface prevents further reaction of Zn underneath, which leads to low utilization of active material and poor rechargeability. Second, soluble intermediates change Zn anode morphology over cycling. In this work, an ion‐sieving carbon nanoshell coated ZnO nanoparticle anode is reported, synthesized in a scalable way with controllable shell thickness, to solve the problems of passivation and dissolution simultaneously. The nanosized ZnO prevents passivation, while microporous carbon shell slows down Zn species dissolution. Under extremely harsh testing conditions (closed cell, lean electrolyte, no ZnO saturation), this Zn anode shows significantly improved performance compared to Zn foil and bare ZnO nanoparticles. The deeply rechargeable Zn anode reported is an important step toward practical high‐energy rechargeable aqueous batteries (e.g., Zn‐air batteries). And the ion‐sieving nanoshell concept demonstrated is potentially beneficial to other electrodes such as sulfur cathode for Li‐S batteries.