Atomic Sn Encapsulation with Visualizing Mitigated Active Zinc Loss toward Anode-Lean Zinc Metal Battery

Aqueous Zn ion batteries promise high safety and sustainability for large-scale energy storage but are severely impeded by catastrophic dendrite growth and parasitic reactions of Zn anode with irreversible Zn loss. Constructing ultrafine zincophilic seeding sites in hosting interphases has emerged as a viable strategy for reversible plating/stripping. Nevertheless, systematic unravelling of downsized nucleation sites and spatial distribution along with manifesting active Zn loss mechanism, remains scant yet imperative. Herein the atomic Sn encapsulated in hollow carbon spheres is proposed (At-Sn@HCN) as interphase combined with in situ optical microscope for visualizing the active Zn loss. The atomic-level Sn serves as robust nucleation sites to minimize nucleation barrier while the hollow architecture homogenizes the local charge distribution. Consequently, dense Zn deposition is visualized with neglected Zn loss for At-Sn@HCN, in sharp contrast to hollow carbon spheres (HCN) and bulk Sn-loaded HCN visualizing dead Zn formation and interphase peeling off, respectively. Consequently, the full cells achieve prolonged cycling under anode-lean configuration for 500 cycles, and even can be stably operated under negative to positive areal capacity ratio of 2.2 with alleviated decay rate, superior to those of most reported literatures. These findings open up new horizons for practical deployment of Zn metal batteries.