energy, and kinetic energy have been developed. [2] In these self-charging power systems, energy resources are essential. Nonetheless, in some specific conditions, external energy resources are not always available. Furthermore, the components of rechargeable batteries integrated with external energy resources were complicated compared with two-electrode cells, for example, photoelectrodes in photorechargeable batteries were required. [3] Chemical energy, as a kind of internal energy from molecules, can be converted into electric energy by redox reaction. [4,5] Chemical energy of oxygen in air makes metal-air batteries attractive, and can be utilized to charge other energy storage devices. [6] However, when the charge of metal-air batteries and other energy storage devices are exhausted, external power charge is also required. Therefore, seeking a self-charging system that does not require externally applied energy is of great significance to future battery development.Vanadium oxide (VO 2 ), as a promising cathode for aqueous zinc-ion battery (AZIB), has attracted much attention due to their high capacities, low cost, and various redox properties. [7][8][9] Wang et al. developed a low cost quasi-solid-state aquation zinc ion microbattery based on VO 2multi-walled carbon nanotubes with ultrahigh energy density, and the battery also shows excellent flexibility and thermostability. [10] In the fully discharged state, the reduction of vanadium occurs with the Zn 2+ insertion, and low-valent vanadium Conventional self-charging systems are generally complicated and highly reliant on the availability of energy sources. Herein, a chemically selfcharging, flexible solid-state zinc ion battery (ssZIB) based on a vanadium dioxide (VO 2 ) cathode and a polyacrylamide-chitin nanofiber (PAM-ChNF) hydrogel electrolyte is developed. With a power density of 139.0 W kg -1 , the ssZIBs can deliver a high energy density of 231.9 Wh kg -1 . The superior electrochemical performance of the ssZIBs is attributed to the robust tunnel structure of the VO 2 cathode and the entangled network of PAM-ChNF electrolyte, which provide efficient pathways for ion diffusion. Impressively, the designed ssZIBs can be chemically self-charged by the redox reaction between the cathode and oxygen in ambient conditions. After oxidation for 6 h in air, the ssZIBs manifest a high discharging capacity of 263.9 mAh g -1 at 0.2 A g -1 , showing excellent self-rechargeability. With the assistance of a small amount of acetic acid added to the hydrogel electrolyte, the galvanostatic discharging and chemical self-charging cycles can reach 20. More importantly, such ssZIBs are able to operate well at chemical or/and galvanostatic charging hybrid modes, demonstrating superior reusability. This work brings a new prospect for designing flexible chemically self-charging ssZIBs for portable self-powered systems.

Despite the enormous potential of aqueous zinc (Zn)‐ion batteries as a cost‐competitive and safer power source, their practical applications have been plagued by the chemical/electrochemical instability of Zn anodes with aqueous electrolytes. Here, ionic liquid (IL) skinny gels are reported as a new class of water‐repellent ion‐conducting protective layers customized for Zn anodes. The IL skinny gel (thickness ≈500 nm), consisting of hydrophobic IL solvent, Zn salts, and thiol‐ene polymer compliant skeleton, prevents the access of water molecules to Zn anodes while allowing Zn2+ conduction for redox reactions. The IL‐gel‐skinned Zn anode enables sustainable Zn plating/stripping cyclability under 90% depth of discharge (DODZn) without suffering from water‐triggered interfacial parasitic reactions. Driven by these advantageous effects, a Zn‐ion full cell (IL‐gel‐skinned Zn‐anode||aqueous‐electrolyte‐containing MnO2 cathode) exhibits high charge/discharge cycling performance (capacity retention ≈95.7% after 600 cycles) that lies beyond those achievable with conventional aqueous Zn‐ion battery technologies.

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