Ultrathin nitrogen-rich porous carbon nanosheets with fluorine doping for high-performance potassium storage

Abstract

Potassium ion batteries (KIBs) are considered as a promising substitute for lithium ion batteries (LIBs) due to potassium abundant and low-cost. Nevertheless, serious volume expansion and sluggish kinetics caused by repeated insertion/extraction of K+ with larger radius frequently restrict the K+ storage performance. Herein, we explored ultrathin nitrogen-rich carbon nanosheets with fluorine doping (CPTHB-F) as the anode in KIBs by carbonizing a rigid polymer porous framework (PTHB) and polytetrafluoroethylene (PTFE). The CPTHB-F possesses short distance of potassium ion mobility, large interlayer spacing and more exposed active sites. As a result, KIBs with CPTHB-F anode exhibits a high specific capacity of 115.3 mA h g–1 at a high current density of 5.0 A g–1. Moreover, the long-term stability of CPTHB-F is excellent which shows a negligible capacity loss of 0.05% per cycle corresponding to a high capacity of 137.3 mA h g–1 after 690 cycles at the current density of 0.5 A g–1. This work provides a new strategy to construct carbon materials for the reversible potassium ion storage.