Peapod-like MnO@Hollow carbon nanofibers film as self-standing electrode for Li-Ion capacitors with enhanced rate capacity

Lithium ion capacitors (LICs), combining with the advantages of supercapacitors and batteries, are considered as one of the most attractive energy storage devices. The key point of constructing high-performance LICs is to address the sluggish kinetics behavior of battery-type anode. Herein, we demonstrate that nano-MnO with low Li-ion insertion voltage and fast kinetics can be favorably used for LICs. Self-standing hollow carbon-encapsulated MnO nanofibers film (MnO@HCF) is synthesized through a morphology-inheritance route, exhibiting high electrical conductivity, good structural stability, and continuous open channels to facilitate electrolyte ion transportation. Such a synergistic structure endows MnO@HCF with excellent electrochemical properties including a considerably enhanced capacity of 586.8 mAh g(-1) at a current density of 0.1 A g(-1). The LIC based on the MnO@HCF anode and activated carbon cathode deliver a high energy density of 87.4 Wh kg(-1) at 215 W kg(-1), under a high mass loading of 7.1 mg cm(-2). Even at an ultrahigh power density of 10750 W kg(-1), the energy density can still reach 50.6 Wh kg(-1). Additionally, the LIC exhibits a remarkable capacity retention of 98.6% after 3000 cycles at 1075 W kg(-1).