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Oxygen Reduction Reaction Promotes Li + Desorption from Cathode Surface in Li‐O 2 Batteries
Author(s) -
Haro Marta,
Vicente Nuria,
GarciaBelmonte Germà
Publication year - 2015
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201500369
Subject(s) - desorption , electrolyte , electrochemistry , oxygen , adsorption , materials science , electrode , cathode , capacitance , battery (electricity) , chemical engineering , analytical chemistry (journal) , nanotechnology , chemistry , thermodynamics , organic chemistry , chromatography , engineering , power (physics) , physics
Li‐O 2 batteries are claimed to be one of the future energy storage technologies. Great number of scientific and technological challenges should be solved first to transform Li‐O 2 battery from a promise to real practical devices. Proposed mechanisms for oxygen reduction assume a reservoir of solved Li + ions in the electrolyte. However, the role that adsorbed Li + on the electrode surface might have on the overall oxygen reduction reaction (ORR) has not deserved much attention. Adsorbed Li + consumption is monitored here using impedance measurements from extended electrochemical double layer capacitance, which depends on the carbon matrix surface area. The presence of O 2 drastically reduces the amount of adsorbed Li + , signaling the kinetic competition between Li + surface adsorption and its consumption, only for potentials corresponding to the oxygen reduction reaction. Noticeably double layer capacitance remains unaltered after cycling. This fact suggests that the ORR products (Li 2 O 2 and Li 2 CO 3 ) are not covering the internal electrode surface, but deposited on the outer electrode‐contact interface, hindering thereby the subsequent reaction. Current results show new insights into the discharge mechanism of Li‐O 2 batteries and reveal the evidence of Li + desorption from the C surface when the ORR starts.