Constructing High‐Performance Li‐ion Capacitors via Cobalt Fluoride with Excellent Cyclic Stability as Anode and Coconut Shell Biomass‐Derived Carbon as Cathode Materials

Abstract

AbstractThe Lithium‐ion capacitor (LIC) is a potential candidate for the next generation of energy storage devices due to high power density, high energy density and excellent cycle stability. Nonetheless, the problem of matching optimization is still faced for LIC. Many different approaches are explored to find a balance between the two storage mechanisms so that high performance LICs can be obtained. Here, CoF2, prepared by solvothermal method, showed reversible specific capacity of 307 mAh g−1 after 900 cycles at 0.1 A g−1 and 81 mAh g−1 after 10,000 cycles at 4 A g−1. Meanwhile, coconut shell is used as precursor for preparing natural porous carbon as cathode materials of LIC. The coconut shell biomass carbon (CSBC‐5), outstanding specific surface area (2767 m2 g−1), holds a capacity of 120 mAh g−1 after 1000 cycles at 1 A g−1. The LIC, CoF2 as anode and CSBC‐5 as cathode, shows excellent cycle stability (65 % capacity retention after 5000 cycles), higher energy density of 82 Wh kg−1 (at power density of 190 W kg−1) and higher power density of 3800 W kg−1(at energy density of 50 Wh kg−1). Therefore, the material of CoF2 is a promising choice for the future anode and promotes the development of LIC.