Integrated design of aqueous zinc-ion batteries based on dendrite-free zinc microspheres/carbon nanotubes/nanocellulose composite film anode

With the booming development of wearable electronics, flexible zinc-based batteries are attracting significant attention due to their high safety, low cost, environmental benignity, and relatively large energy/power densities. However, in a conventional segregated configuration, the electrodes could be easily detached from the separator when the battery is subjected to bending strain, which would dramatically depress electrochemical performances. Moreover, severe zinc dendrite growth and parasitic side reactions at the anode are extremely detrimental to the durability and the reliability of zinc-based batteries. Herein, a flexible self-standing composite film anode consisting of zinc microspheres, carbon nanotubes, and nanocellulose is constructed to replace the conventional Zn foil. It is found that the use of this anode can effectively inhibit the dendrites and side reactions, thereby substantially improving the cyclability. In addition, a layer-by-layer vacuum filtration method is used to integrate the composite film anode with a cellulose separator and a MnO2-based composite film cathode into a single matrix. The unique integrated battery realizes great rate capability and cycling stability, and more importantly, superior affordability to bending deformations. Besides, the commonly used thick, heavy, and expensive current collectors are no longer required in the integrated configuration, therefore enabling the battery to be smarter and cheaper. This study not only opens a new option for building dendrite-free zinc anodes but also discloses a facile strategy to achieve integrated configuration for energy storage devices.