Ion pre-intercalation and OER modified carbon fiber paper towards high-performance cathode for dual-ion batteries

Abstract

Carbon materials with layered structure and high conductivity are promising electrode candidates for dual-ion batteries (DIBs). However, the size mismatch of electrolyte ions and interlayer spacing of carbon materials limits the overall performance of DIBs. Thus, finding an effective strategy to adjust the interlayer spacing of carbon materials is of great importance. Here, we describe an efficient electrochemical strategy combining ion pre-intercalation and gas evolution reaction treatment to expand the interlayer spacing and modify graphene layers of carbon fiber papers. Furthermore, through the theoretical calculation we have demonstrated that the anion adsorption energy is reduced and kinetics is accelerated by the introduction of functional groups on the graphene layer. After the electrochemical modification, the discharge capacity of CFP increases more than 50%, the transfer resistance reduces even more than 40% and the capacity retains 94% after 1000 cycles in an ionic liquid electrolyte. These promising results demonstrate an effective and convenient method to solve the size mismatch issue, and therefore, arouse the potentials of carbon materials and other materials with layered structure for high performance DIBs.