Spontaneous passivation of selective Zn(101) plating via dangling bond saturation and electrostatic interaction regulation for high-utilization, fast-kinetics zinc anodes†

Abstract

Although Zn(101) exhibits faster Zn²⁺ plating/stripping kinetics and stronger bonding with Zn²⁺ compared to Zn(002), the application of Zn(101) in Zn batteries has been limited due to its higher reactivity with water. However, a novel approach utilizing spontaneous self-passivation of plated Zn(101) offers the potential to harness its favorable kinetics and stronger Zn–Zn bonding for battery applications. Here, we present a high-utilization and fast-kinetics Zn anode by promoting selective (101) facet growth and achieving spontaneous passivation of the underlying Zn plating. A non-stoichiometric Sn–O system is selected as the modification material because of its ability to engineer crystal structures (amorphous, rutile, and layered) and manipulate electrical polarity (n-type vs. p-type). The optimized p-type SnO_1.17 saturates dangling bonds of Zn(101), benefiting the preferential growth of well-aligned Zn(101) planes. Besides, the Zn²⁺ plating location is altered underlying the interphase due to synergetic effects of lower Zn²⁺ migration barriers of the layered structure and electron-blocking properties of SnO_1.17. Consequently, a high Zn utilization ratio of over 91.5% is achieved in 800 hours, with an impressively low overpotential of 43 mV. Furthermore, an anode-free system combining a ZnMn₂O₄ cathode and a SnO_1.17@Cu anode retained 81.6% capacity after 200 cycles.