Co3O4-based binder-free cathodes for lithium–oxygen batteries with improved cycling stability

Abstract

A novel binder-free electrode for lithium–oxygen batteries has been prepared by electrodepositing a Co₃O₄ layer onto a pretreated TiO₂ fiber mesh, formed on nickel foam by an electrospinning method. The Co₃O₄ depositing layer is composed of Co₃O₄ nanoflakes, forming a uniform flower-like porous structure. The Co₃O₄ nanoflakes within the depositing layer provide a large amount of catalytic active sites for oxygen evolution and reduction reactions. The three-dimensional porous network of the Co₃O₄ depositing layer can not only facilitate the transportation of ions and electrolyte within the electrode, but also provide plenty of space to accommodate Li₂O₂ species formed during the discharge process. The Co₃O₄ spheres embedded in the TiO₂ fiber mesh, formed by the treatment of a suspension of cobaltammine precipitate, function as anchors to prevent the detachment of the Co₃O₄ layer from the current collector, resulting in excellent structural and cycling stability. Only a slight specific capacity decay is observed at full discharge/charge after 80 cycles. This work demonstrates the important factors in the preparation of binder-free cathodes for high performance lithium–oxygen batteries.