Thermal and electrochemical decomposition of lithium peroxide in non-catalyzed carbon cathodes for Li–air batteries

Abstract

The decomposition of lithium peroxide during the charging process of lithium–air batteries is investigated. A novel preparation method for electrodes in the discharged state, i.e., prefilled with Li₂O₂ using polyethylene oxide as a binder, is presented. The composition and reactivity of Li₂O₂-prefilled electrodes are examined by thermal analysis coupled with on-line mass spectrometry. Voltage profiles and gas evolution during the charging process of Li₂O₂-prefilled electrodes in battery cells are correlated with the thermal decomposition process of Li₂O₂ and its impact on other electrode compounds. It is found that both thermal Li₂O₂ decomposition and the electrochemical decomposition of Li₂O₂ during charging enhance the oxidation of the electrolyte, the binder, and/or carbon, which is suggested to be due to the formation of “nascent” oxygen during Li₂O₂ decomposition into O₂ and Li₂O (thermally) or into O₂ and lithium ions (electrochemically).