3D Hierarchical Co/CoO‐Graphene‐Carbonized Melamine Foam as a Superior Cathode toward Long‐Life Lithium Oxygen Batteries. (21st January 2016) - Zhang, Peng
Abstract : Carbon based materials as one promising cathode to accommodate the insoluble and insulating discharge products (Li2 O2 ) for lithium oxygen (Li‐O2 ) batteries have attracted great attention due to their large energy density store ability compared with the other carbon‐free cathodes. However, the side reaction occurring at carbon/Li2 O2 interfaces hinders their large‐scale application in Li‐O2 batteries. Herein, a simple and cost‐effective strategy is developed for the growth of core‐shell‐like Co/CoO nanoparticles on 3D graphene‐wrapped carbon foam using 3D melamine foam as the initial backbone. This unique 3D hierarchical carbonized melamine foam‐graphene‐Co/CoO hybrid (CMF‐G‐Co/CoO) with a continuous conductive network and elastic properties is used as binder‐free oxygen electrode for Li‐O2 batteries. Electrochemical and structural measurements show that a synergistic effect is observed between Co/CoO and graphene, where Li2 O2 grows on the Co/CoO surfaces instead of the carbon surfaces at the initial discharge state (500 mAh g total − 1 ), indicating the reduced carbon/Li2 O2 interfaces and alleviative side reactions during the electrochemical process. Importantly, the CMF‐G‐Co/CoO electrode can achieve greatly improved cycle life over the electrode without aid of the Co/CoO. Furthermore, it delivers a large capacity of ≈7800 mAh g total − 1 and outstanding rate capability, exhibiting the great potential for the application in Li‐O2 batteries. Abstract : Core–shell structured Co/CoO with high LiO2 adsorption energy is proven to be a superior preservative for carbon‐based Li‐O2 batteries. The design is based on a 3D Co/CoO‐graphene‐carbonized polymer foam. The preservative reduces the side reaction and improves the cycle stability of Li‐O2 batteries by inducing Li2 O2 growth on itself instead of the carbon surfaces.