The strong activity of water molecules causes a series of parasitic side reactions on Zn anodes in the aqueous electrolytes. Herein, we introduce silk fibroin (SF) as a multifunctional electrolyte additive for aqueous zinc-ion (Zn-ion) batteries. The secondary structure transformation of SF molecules from α-helices to random coils in the aqueous electrolytes allows them to break the hydrogen bond network among free water molecules and participate in Zn2+ ion solvation structure. The SF molecules released from the [Zn­(H2O)4(SF)]2+ solvation sheath appear to be gradually adsorbed on the surface of Zn anodes and in situ form a hydrostable and self-healable protective film. This SF-based protective film not only shows strong Zn2+ ion affinity to promote homogeneous Zn deposition but also has good insulating behavior to suppress parasitic reactions. Benefiting from these multifunctional advantages, the cycle life of the Zn||Zn symmetric cells reaches over 1600 h in SF-containing ZnSO4 electrolytes. In addition, by adopting a potassium vanadate cathode, the full cell shows excellent cycling stability for 1000 cycles at 3 A g–1. The in situ construction of a protective film on the Zn anode from natural protein molecules provides an effective strategy to achieve high-performance Zn metal anodes for Zn-ion batteries.

The advancements in wearable electronic devices make it urgent to develop highperformance flexible lithium-ion batteries (LIBs) with excellent mechanical and electrochemical properties. Herein, we design a new 3D hierarchical hybrid sandwich flexible structure by anchoring SnO 2 nanosheets (SnO 2-NSs) on flexible carbon cloth and coating with thin amorphous carbon (AC) layer (CF@SnO 2-NS@AC). The carbon cloth substrate works as the backbone and the current collector, while the thin AC layer provides extra support during the electrode expansion. The new architecture can be utilised as a binder-free electrode and presents extraordinary mechanical flexibility and outstanding electrical stability under external stresses. The new electrode can deliver a specific capacity as high as 968.6 mAh g-1 after 100 cycles at 85 mA g-1 , which also shows remarkable rate capability and an excellent high current cycling stability. The outstanding electrochemical performance combined with the high mechanical flexibility and invariable electrical conductivity during/after different bending cycles make the new structure a promising oxide anode for flexible batteries. With the possibility of using a similar approach to design flexible cathode, the present work opens the door to empower the next-generation wearable devices and smart clothes with a robust and reliable battery.

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