Design of Quadruple-Layered Metal Oxides/Nitrogen, Oxygen-Doped Carbon Nanotube Arrays as Binder-free Electrodes for Flexible Lithium-ion Batteries

Abstract Designing flexibly binder-free metal oxide electrodes, which could effectively alleviate the mechanical stress and maintain the structural integrity during the lithiation/delithiation process, is still a major challenge. Here we report a facile strategy for successfully synthesizing free-standing quadruple-layered metal oxides/nitrogen, oxygen-doped carbon nanotube array electrodes. In the quadruple-layered structure, metal oxides are protected by carbon layer to minimize the direct exposure to the electrolyte and accommodate the huge volume change during cycling, and thus form the solid-electrolyte interface layer. Besides that, the abundant oxygen and nitrogen-containing functional groups of carbon layer shows a strong interaction with metal oxides to prevent the electrode pulverization during charging and discharging. Meanwhile, carbon layer is introduced to facilitate the stable and fast electrons mobility. As a result, the as-prepared quadruple-layered electrodes show excellent electrochemical performance in terms of high reversible capacity, good rate capability, and stable cyclability. This work may pave the way for the construction of flexible binder-free lithium ion batteries with superior lithium storage properties.