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Nanosized Carbon‐Supported Manganese Oxide Phases as Lithium–Oxygen Battery Cathode Catalysts
Author(s) -
Kavakli Cüneyt,
Meini Stefano,
Harzer Gregor,
Tsiouvaras Nikolaos,
Piana Michele,
Siebel Armin,
Garsuch Arnd,
Gasteiger Hubert A.,
Herranz Juan
Publication year - 2013
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201300331
Subject(s) - manganese , inorganic chemistry , hydrogen peroxide , peroxide , chemistry , catalysis , lithium (medication) , oxygen , lithium hydroxide , cathode , electrolyte , carbon fibers , oxide , lithium vanadium phosphate battery , oxygen evolution , battery (electricity) , electrochemistry , materials science , electrode , organic chemistry , ion , ion exchange , medicine , power (physics) , physics , quantum mechanics , composite number , composite material , endocrinology
The poor discharge and recharge efficiency demonstrated by lithium–air batteries renders the search for highly active and inexpensive oxygen reduction and evolution catalysts crucial to the development of these energy‐storage and conversion devices. Previous works have shown that manganese oxides are promising lithium–oxygen cathode catalysts, which is in agreement with their remarkable activities for the reduction and evolution of oxygen in aqueous media. Motivated by these resembling catalytic behaviors, we prepared and characterized a number of manganese oxide modifications directly on carbon black and attempted to correlate their oxygen reduction and evolution activities in aprotic and aqueous electrolytes. Although our results cannot confirm this correlation, they provide valuable insight into the reaction mechanisms at play in each medium. More precisely, in 0.1 M potassium hydroxide, the reduction of oxygen is related to the reduction of a manganese(III) intermediate whereas the oxidation of hydrogen peroxide (which was regarded as a mimic of the lithium peroxide produced upon lithium–oxygen battery discharge) correlates with the transition between manganese(II) and manganese(III) phases. In the aprotic medium, manganese oxide cathodes prefilled with lithium peroxide showed a strong catalytic effect but were not active in the oxidation of lithium peroxide produced in the previous discharge. This discrepancy is thought to arise from the stark differences in the sizes and morphologies of the lithium peroxide involved in each test, which implies that the catalytic activity of a material for the oxidation of lithium peroxide prefilled on electrodes is not indicative of its behavior in the charging of a real lithium–oxygen cell.