Nature of Zinc-Derived Dendrite and Its Suppression in Mildly Acidic Aqueous Zinc-Ion Battery

Abstract

Aqueous zinc-ion batteries (ZIBs) are attractive in energy storage due to the use of aqueous electrolytes that ensures safety and ease of handling all parts in air. However, catastrophic zinc dendritic growth on zinc metal anode impedes their practical application. Herein, we introduce Zn3(PO4)3·4H2O (ZP)-coated zinc metal anode, to effectively suppress the dendrite growth and first elucidate the chemical state of dendrite that is composed of metallic Zn0, ZnO, and Zn(OH)2. Significant improvement is observed for the ZP-coated zinc metal symmetric cell. Operando synchrotron tomography demonstrates that the ZP-coating layer ensures uniform deposition of zinc-derived compounds by the ZP layer that scarifies itself through decomposition to P2O5, Zn0, and Zn(OH)2. Meanwhile, the local reaction between P2O5 and H2O reproduces H3PO4, which provides a condition to reproduce Zn3(PO4)2·4H2O via a reaction between H3PO4 and metallic Zn on the Zn metal anode. This cyclic re-formation of Zn3(PO4)2·4H2O progressively prevents the dendritic for long-term even at high rates. The compatibility is verified in NaV3O8||ZP-coated zinc anode cell over 1000 cycles. As a result, this finding presents a practical way for uniform deposition of Zn that can be applicable to aqueous and non-aqueous ZIBs.