Annealing induced a well-ordered single crystal δ-MnO(2) and its electrochemical performance in zinc-ion battery

Herein, the formation and electrochemical performance of a novel binder-free turbostratic stacked/ well-ordered stacked δ-MnO(2)-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 interconnected δ-MnO(2) crumpled nanosheets on a carbon fiber substrate. Moreover, an improvement via a simple annealing strategy in the stacking, surface area and conductivity of the δ-MnO(2) sheets was observed. Annealing induces the rearrangement of δ-MnO(2) sheets resulting in the transformation from turbostratic stacking to a well-ordered stacking of [Formula: see text] -MnO(2) sheets, as indicated by the selected area electron diffraction (SAED) hexagonal single crystal pattern. Besides, the formation of the well-ordered stacking of [Formula: see text] -MnO(2) 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-MnO(2)-C fiber composite with a well-ordered stacking of δ-MnO(2) sheets. This study also demonstrated comparable electrochemical performance between the turbostratic [Formula: see text] -MnO(2) sheets and the well-ordered stacked δ-MnO(2) sheets.