A Layer-by-Layer Self-Assembled Biomacromolecule Film for Stable Zinc Anode.

Side reactions on zinc metal anodes are formidable issues that cause limited battery life of aqueous zinc ion batteries (AZIBs). Here, we deploy a facile and controllable layer-by-layer (LbL) self-assembly technique to construct an ion-conductive and mechanically robust electrolyte/anode interface for stabilizing the Zn anode. The LbL film consists of two natural and biodegradable biomacromolecules, chitosan (CS) and sodium alginate (SA). We show that such an LbL film tailors the solvation sheath of Zn ions and facilitates the oriented deposition of Zn. Symmetric cells with the four double layers of CS/SA ((CS/SA) 4 -Zn) exhibit stable cycles for over 5200 h. The (CS/SA) 4 -Zn||H 2 V 3 O 8 coin cell maintains a specific capacity of 125.5 mAh∙g -1 after 14000 cycles. The pouch cell with an electrode area of 5×7 cm 2 also presents a capacity retention of 83% for over 500 cycles at 0.1 A g -1 . No obvious dendrites are observed after long cycles in both symmetric and full cells. Given the cost-effective material and fabrication, and environmental friendliness of the LbL films, this Zn protection strategy may boost the industrial application of AZIBs. This article is protected by copyright. All rights reserved.