AUTHOR=De Luna Yannis , Alsulaiti Asma , Ahmad Mohammad I. , Nimir Hassan , Bensalah Nasr 

TITLE=Electrochemically stable tunnel-type α-MnO2-based cathode materials for rechargeable aqueous zinc-ion batteries

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1101459

DOI=10.3389/fchem.2023.1101459

ISSN=2296-2646

ABSTRACT=<p>The purpose of this study is the synthesis of α-MnO<sub>2</sub>-based cathode materials for rechargeable aqueous zinc ion batteries by hydrothermal method using KMnO<sub>4</sub> and MnSO<sub>4</sub> as starting materials. The aim is to improve the understanding of Zn<sup>2+</sup> insertion/de-insertion mechanisms. The as-prepared solid compounds were characterized by spectroscopy and microscopy techniques. X-ray diffraction showed that the hydrothermal reaction forms α-MnO<sub>2</sub> and Ce<sup>4+</sup>-inserted MnO<sub>2</sub> structures. Raman spectroscopy confirmed the formation of α-MnO<sub>2</sub> with hexagonal MnO<sub>2</sub> and Ce-MnO<sub>2</sub> structures. Scanning electron microscopy (SEM) confirmed the formation of nanostructured MnO<sub>2</sub> (nanofibers) and Ce-MnO<sub>2</sub> (nanorods). The electrochemical performance of MnO<sub>2</sub> was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) tests in half-cells. CV results showed the reversible insertion/de-insertion of Zn<sup>2+</sup> ions in MnO<sub>2</sub> and Ce-MnO<sub>2</sub>. GCD cycling tests of MnO<sub>2</sub> and Ce-MnO<sub>2</sub> at 2500 mA/g demonstrated an impressive electrochemical performance, excellent cycling stability throughout 500 cycles, and high rate capability. The excellent electrochemical performance and the good cycling stability of MnO<sub>2</sub> and Ce-MnO<sub>2</sub> nanostructures by simple method makes them promising cathode materials for aqueous rechargeable zinc-ion batteries.</p>