Ion Tunnel Matrix Initiated Oriented Attachment for Highly Utilized Zn Anodes.

ABSTRACT

Metallic zinc is an ideal anode for aqueous energy storage; however, Zn anodes suffer from nonhomogeneous deposition, low reversibility, and dendrite formation; these lead to an overprovision of zinc metal in full cells. Herein, oriented-attachment-regulated Zn stacking initiated through a trapping-then-planting process with a high zinc utilization rate (ZUR) is reported. Due to the isometric topology features of cubic-type Prussian blue analog (PBA), the initial Zn plating occurs at specific sites with equal spacing of ≈5 Å in the direction perpendicular to the substrate; the trace amount of zinc ions trapped in tunnel matrix provides nuclei for the oriented attachment of Zn (002) deposits. As a result, the PBA-decorated substrate delivers high reversibility of dendrite-free zinc plating/stripping for more than 6600 cycles (1320 h) and achieves an average Coulombic efficiency (CE) of 99.5% at 5 mA cm-2 with 100% ZUR. Moreover, the anode-limited full cell with a low negative-positive electrode ratio (N/P) of 1.2 can be operated stably for 360 cycles, displaying an energy density of 214 Wh kg-1 ; this greatly exceeds commercial aqueous batteries. This work provides a proof of concept design of metal anodes with a high utilization ratio and a practical method for developing high-energy-density batteries.