Binder-free flexible zinc-ion batteries: one-step potentiostatic electrodeposition strategy derived Ce doped-MnO2 cathode

Abstract With the development of flexible electronic devices, power sources' higher safety, lighter, and bending ability have been demanded in recent years. While, aqueous zinc-ion batteries (ZIBs) have gained much attention due to their low cost, rich zinc resources, and high safety. Hence, they have been considered the most promising secondary battery in the near future. However, the practical application of aqueous ZIBs is still impeded by the unsatisfied performance of the cathode materials and the complex manufacturing process. Moreover, the electrochemical energy storage process and mechanism of the cathodes at the flexible ZIBs still remain ambiguous and under discussion, which severely limited the development of the ZIBs. Herein, a Ce doped-MnO2 binder-free cathode electrode was prepared via a one-step potentiostatic electrodeposition strategy. A flexible ZIB assembled based on the Ce-MnO2@CC cathode and a homemade gel electrolyte exhibits a high reversible specific capacity (∼311 mAh g−1), a significant energy density (370 Wh kg−1), an excellent stability performance, and achieves good electrochemical behavior even under different bending conditions. Furthermore, the energy storage mechanism of the flexible ZIBs with Mn-based oxides cathode was monitored by the in-situ Raman, XRD, SEM, and TEM, revealing the reversible insertion/extraction of Zn2+ and H+ during the charge/discharge process. Moreover, the results also demonstrate that the structural shedding, and dissolution of the MnO2 structure are the major factors in reducing capacity. This research opens up new opportunities for flexible ZIBs in the field of portable and wearable electronics.