Annealing induced a well-ordered single crystal δ-MnO2
Herein, the formation and electrochemical performance of a novel binder-free turbostratic stacked/ well-ordered stacked δ-MnO2-carbon fiber composite cathodes in deep eutectic solvent (DES) based zinc-ion battery (ZIB) is reported. Results of morphological, elemental, and structural analyses revealed directly grown and interconnectedδ-MnO2crumpled nanosheets on a carbon fiber substrate. Moreover, an improvement via a simple annealing strategy in the stacking, surface area and conductivity of theδ-MnO2sheets was observed. Annealing induces the rearrangement ofδ-MnO2sheets resulting in the transformation from turbostratic stacking to a well-ordered stacking of𝛿δ-MnO2 sheets, as indicated by the selected area electron diffraction (SAED) hexagonal single crystal pattern. Besides, the formation of the well-ordered stacking of 𝛿δ-MnO2 sheets exhibited improved electrochemical performance and cyclability, as cathode material for ZIB. The novel strategy described in this study is an essential step for the development of binder-free δ-MnO2-C fiber composite with a well-ordered stacking of δ-MnO2 sheets. This study also demonstrated comparable electrochemical performance between the turbostratic 𝛿δ-MnO2 sheets and the well-ordered stacked δ-MnO2 sheets.