Ultra-high capacity dual-ion batteries realized by few-layered reduced graphene oxide and cathode structure design

Abstract

As the development of dual-ion batteries (DIBs) is limited by the capacity of anions intercalation, we put forward an innovative design idea of DIB. Compared with the traditional graphite cathodes, few-layered reduced graphene oxide (rGO) has a large specific surface area and can greatly improve the utilization ratio of carbon layers for fast redox reaction process. In addition, the carbon paper current collector with porous network structure facilitates the uniform distribution of active materials, rapid penetration of electrolyte and fast migration of ions, and also relieves the volume strain caused by PF6− intercalation/de-intercalation. Under the effects of the above two aspects, the lithium-rGO DIB demonstrates significantly enhanced electrochemical performance compared with conventional DIBs. It possesses an ultra-high discharge capacity of 405 mA h g−1 with a coulombic efficiency of > 98% after 1000 cycles at 1 A g−1 in the voltage range of 3.0–5.0 V. The detailed mechanism of electrochemical performance enhancement is also discussed.