CO2-adsorbent spongy electrode for non-aqueous Li–O2 batteries

Abstract Regulation of the Li2CO3 byproduct is the most critical challenge in the field of non-aqueous Li–O2 batteries. Although considerable efforts have been devoted to preventing Li2CO3 formation, no approaches have suggested the ultimate solution of utilizing the clean Li2O2 reaction instead of that of Li2CO3. Even if extremely pure O2 is used in a Li–O2 cell, its complete elimination is impossible, eventually generating CO2 gas during charge. In this paper, we present the new concept of a CO2-adsorbent spongy electrode (CASE), which is designed to trap the evolved CO2 using adsorption materials. Various candidates composed of amine functional groups (–NH2) for capturing CO2 were screened, with quadrapurebenzylamine (QPBZA) exhibiting superior CO2-adsorbing ability among the proposed candidates. Accordingly, we fabricated the CASE by sandwiching QPBZA between porous carbon layers, which facilitated the transport of gaseous products. The new electrode was demonstrated to effectively capture the evolved CO2 during charge, therefore altering the reaction pathways to the ideal case. It is highly advantageous to mitigate the undesirable CO2 incorporation in the next discharge, resulting in improved cyclability. This novel concept of a CO2-sponging electrode provides an alternative route to the realization of practically meaningful Li–O2 batteries.