Lithium ion supercapacitor composed by Si-based anode and hierarchal porous carbon cathode with super long cycle life

A lithium ion supercapacitor full cell is fabricated with a Fluorine-doped carbon encapsulated SiOx as anode and a Nitrogen-doped carbon with hierarchical meso-micro porous structure as cathode. Benefited from the fast kinetic lithium reaction as well as longevity in the newly synthesized Si-base anode and high capacitance on the porous carbon, the hybrid device delivering of high power density, high energy density and super long cycle life is demonstrated. After prelithiation of Si-base anode, this hybrid supercapacitor exhibits a high capacity of 120 mAh g−1 at 0.2 A g−1 after 1600 cycles. A capacity of 42 mAh g−1 can still be obtained even under the current density of 3 A g−1. Furthermore, Super long cycle life (45 mAh g−1 capacity with 1 A g−1 after 10,000 cycles), low leakage current (3.8 μA) and low self-discharge (82% voltage retention after 48 h resting in open-circuit potential) are revealed. This work presents not only a simple route for the synthesis of Si-base anode for energy storage devices on lithium chemistry, but also a new approach to the construction of hybrid battery-capacitor device.