Ti3C2/fluorine-doped carbon as anode material for high performance potassium-ion batteries

Abstract

Potassium ion batteries (PIBs) attract increasing attention due to abundant natural storage of potassium resources in the earth’s crust, low cost, and high operating potential. However, larger radius of K+ compared to Na+/Li+, poor kinetics and unstable structure lead to inferior electrochemical performance for PIBs. Herein, we propose 3D fluorine-doped carbon@Ti3C2 MXene (3D FC@Ti3C2) composite as anode material for PIBs. In the composite, coating carbon can protect Ti3C2 from oxidation and self-stack, fluorine-doped carbon can afford more defects and introduce numerous active site that can strongly adsorb K+. In addition, the composite can enlarge the interlayer spacing, and the 3D interconnected carbon framework can enhance conductivity and alleviate the volume expansion during cycling. Benefiting from these synergetic effects, the 3D FC@Ti3C2 can obtain supernormal electrochemical property with high capacity of 288 mAhg−1 at 100 mAg−1 after 200 cycles and extraordinary cyclic stability of 174 mAhg−1 at 500 mAg−1 after 1000 cycles.