High-performance dual carbon lithium-ion capacitors based on nitrogen-doped 2D carbon nanosheets as both anode and cathode

Abstract

Lithium-ion capacitors (LICs) assembled with the same anode and cathode materials can effectively alleviate the mismatch of reaction dynamics between the anode and cathode, and reduce the production cost. However, it is very challenging to fabricate an electrode with both fast faradic storage capability and double-layer storage behavior. Herein, two-dimension (2D) nitrogen-doped carbon nanosheets (NCN) derived from asphalt petroleum are fabricated through a porous MgO nanosheets template. Nitrogen doping can expand the interlayer distance of the carbon layer, and improve the electrochemical conductivity. The porous structure of NCN can provide a high specific surface area of 1021 m2g − 1, which enables a high specific capacity for the cathode. While the 2D nanosheet structures are beneficial for facilitating the intercalation and adsorption of Li+. Therefore, the as-fabricated NCN exhibit advanced electrochemical performance as both anode and cathode for LICs. As result, the dual-carbon NCN//NCN LIC systems can provide a high energy density of 167 Wh kg−1 at the power density of 240 W kg−1 coupled with excellent cycling durability (85.6% capacity retention for 9000 cycles at 1 A g − 1).