Self-standing reduced graphene oxide/Nb2C MXene paper electrode with three-dimensional open structure for high-rate potassium ion storage

Potassium ion battery (PIBs) is in the primary stage of development, exploring appropriate electrode materials is the key to obtain high performance and practical application. Herein, we design a self-standing reduced graphene (rGO) and Nb2C MXene (3D-rGO/Nb2C) composite paper electrode with three-dimensional porous conductive network by electrostatic absorption self-assembly method. Compared with the compact structure of L-rGO/Nb2C paper electrode via layer-by-layer vacuum filtration approach, the structure design in which the wrinkled rGO is applied as the framework provides a large number of surface active sites and promotes the rapid transfer of K+ to improve the storage capacity and kinetics of potassium ions. Moreover, the 3D-rGO/Nb2C hybrid paper with large specific surface area can effectively accommodate the volume expansion during charging and discharging process and ensure the cycle stability. At current density of 500 mA g(-1), the 3D-rGO/Nb2C hybrid paper electrode delivers an initial capacity of 207 mAh.g(-1), which is maintained at 139 mAh.g(-1) after 1000 cycles. The 3D-rGO/Nb2C hybrid paper combines both diffusion mechanism and pseudo-capacitance mechanism, which significantly improves its electrochemical performance in K-ion storage. These results show the good potential of the 3D-rGO/Nb2C hybrid paper as a high-performance electrode.

Automated summary

Potassium ion batteries (PIBs) are in the initial stage of development, with research focusing on finding suitable electrode materials for high performance and practical application. In this study, a self-standing reduced graphene (rGO) and Nb2C MXene composite paper electrode with a three-dimensional porous conductive network was designed. The structure of the electrode, using wrinkled rGO as the framework, provided numerous surface active sites and facilitated rapid potassium ion transfer to improve storage capacity and kinetics. Furthermore, the hybrid paper electrode with its large specific surface area effectively accommodated volume expansion during charging and discharging, ensuring cycle stability. At a current density of 500 mA g(-1), the 3D-rGO/Nb2C hybrid paper electrode exhibited an initial capacity of 207 mAh.g(-1), maintained at 139 mAh.g(-1) after 1000 cycles. The electrode combined diffusion and pseudo-capacitance mechanisms, resulting in improved electrochemical performance for potassium-ion storage. These results demonstrate the high-performance potential of the 3D-rGO/Nb2C hybrid paper electrode.