A New Concept of an Air-Electrode Catalyst for Li2O2 Decomposition Using MnO2 Nanosheets on Rechargeable Li-O2 Batteries

• Published in: Electrochimica acta Vol. 252; pp. 192 - 199
• Main Authors: Saito, Morihiro, Kosaka, Shinpei, Fujinami, Taichi, Tachikawa, Yusuke, Shiroishi, Hidenobu, Streich, D., Berg, E.J., Novák, Petr, Seki, Shiro
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.10.2017; Elsevier BV
• Subjects: Air-Electrode Catalyst; Batteries; Catalysis; Catalysts; Catalytic activity; Catalytic Activity for Li2O2 Oxidation; Chemical synthesis; Decomposition reactions; Diffraction; Discharge; Electrodes; Electron microscopy; Li-O2 Batteries; Manganese dioxide; Manganese Dioxide Nanosheets; Metal air batteries; Nanosheets; Oxidation; Rechargeable batteries; Scanning electron microscopy; Studies; Li-O2 Batteries; Manganese Dioxide Nanosheets; Air-Electrode Catalyst; Catalytic Activity for Li2O2 Oxidation
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2017.08.183

To improve the charge/discharge properties of a rechargeable Li-O2 battery (LAB), we synthesized a new air-electrode catalyst composed of MnO2 nanosheets (Mn-NSs) and Ketjen Black (KB), i.e., a KB-comp. Mn-NS catalyst. The composite catalyst was synthesized by electrostatically restacking the nanomaterials in a colloidal solution with Li+ and its electro-catalytic activity as an air-electrode for a LAB test cell was evaluated. The KB-comp. Mn-NS catalyst exhibited excellent performance, especially for oxidation of Li2O2 deposited on the surface of the air-electrode during the charging process, which led to enhanced reversibility of the Li2O2 deposition/decomposition reaction during the discharging/charge cycles. Evidence of these reactions was investigated and confirmed by X-ray diffraction analysis and scanning electron microscopy-energy dispersive X-ray spectroscopy. The Li2O2 was deposited and decomposed more homogeneously at the air-electrode with the KB-comp. Mn-NS catalyst than that with only KB. Consequently, the composite catalyst significantly reduced the overpotential and improved the cycleability up to the 27th cycle, even at 0.40mA.