Annealing induced a well-ordered single crystal δ-MnO2 and its electrochemical performance in zinc-ion battery

Herein, the formation and electrochemical performance of a novel binder-free turbostratic stacked/well-ordered stacked delta-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 interconnected delta-MnO2 crumpled nanosheets on a carbon fiber substrate. Moreover, an improvement via a simple annealing strategy in the stacking, surface area and conductivity of the delta-MnO2 sheets was observed. Annealing induces the rearrangement of o-mno, sheets resulting in the transformation from turbostratic stacking to a well-ordered stacking of delta-MnO2, sheets, as indkated by the selected area electron diffraction (SAED) hexagonal single crystal pattern. Besides, the formation of the well-ordered stacking of delta-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 delta-MnO2-C fiber composite with a well-ordered stacking of delta-MnO2 sheets. T his study also demonstrated comparable electrochemical performance between the tin bast atk delta-MnO2 sheets and the well -ordered stacked delta-MnO2 sheets.