Dynamic interface layer regulation with extremely low content of chitosan additive enables stable zinc metal anode

The practical application of aqueous zinc ion batteries (AZIBs) is severely limited by the poor stability of zinc metal anode (ZMA) such as dendrite growth and side reactions. Herein, extremely low content additive, chitosan (CHI), has been induced for ZMA protection. Theoretical and experimental results demonstrate the abundant polar groups enable spontaneous adsorption of CHI molecules onto ZMA surface and the fresh surface of deposition layer, forming a dynamic interface layer. It is conducive to shield the attack of H₂O and improve the anti-corrosion performance of ZMA. And the groups within the other units of CHI were able to capture the Zn²⁺ ions from bulk electrolyte and boost the capture-diffusion-deposition process. Accordingly, the asymmetric and symmetric cells delivered high Coulombic efficiency (99.3 % after 600 cycles) and long cycle life (over 1380 h) at high density of 10 mA cm⁻². Zn||MnO₂ full cells displayed superior electrochemical performance to that of pristine electrolyte, and the pouch cell delivered high energy density of 352 Wh kg⁻¹. This work suggests that the dynamic interface layer regulation induced by extremely low content additives is promising for the development of practical AZIBs with inherent safety, low cost, durable cycle life.