Atomic Sn sites on nitrogen-doped carbon as a zincophilic and hydrophobic protection layer for stable Zn anodes

Abstract

Anodic dendrites and side reaction inhibition are crucial for high-performance, long-lifespan aqueous Zn-ion batteries. Herein, a multifunctional protection layer for stable zinc anodes, i.e., atomic Sn sites anchored on nitrogen-doped carbon supports (Sn NC), is reported. The Sn NC layer can guide Zn nucleation at a nano-level owing to rich atomic zincophilic sites and deliver an even electron distribution with facilitated charge transfer by conductive nitrogen-doped carbon (NC). A fast Zn²⁺ diffusion pathway is built owing to a gradient concentration field created by the hydrophobic/hydrophilic bi-layer configuration of porous Sn NC, leading to an oriented deposition within and at the surface of Sn NC. Accordingly, a surface-inside-interspace sequential deposition is achieved with a three-dimensional (3D) structured coating to ensure a smooth electrode surface in deep cycling. The hydrophobic surficial Sn–N–C layer further blocks water permeation to prevent hydrogen evolution. Therefore, an ultralow nucleation overpotential of 7.5 mV and a stable cycling performance (over 280 h@10 mA h cm⁻²) are achieved in symmetric cells. Both coin-type and pouch-type Zn//MnO₂ full cells exhibit a high rate capability and superior long-term cycling performance. Our work presents a new insight into the design of interface engineering for robust metal anodes in advanced energy storage systems.