Continuously Interconnected N-Doped Porous Carbon for High-Performance Lithium-Ion Capacitors

Abstract

Lithium-ion hybrid capacitors (LICs) possess the fascinating characteristics of both high power density and high energy density simultaneously. However, to design highly compatible cathode materials with a high capacity and anode materials with a high rate performance is still a major challenge because of the mismatch of dynamic mechanisms, greatly limiting the development of LICs. Herein, we report an N−doped porous carbon (N−PC) with a continuously interconnected network as the cathode, matching the dynamic mechanism of the uniquely pseudocapacitive T−Nb2O5 anode without diffusion-controlled behavior. This heteroatom-grafting strategy of the cathode can effectively control the dynamic process to adjust the ion transport efficiency, shortening the gap of kinetics and capacity with the anode. For the energy storage application, the as-prepared N−PC cathode demonstrates an appreciable capacity of 62.06 mAh g−1 under a high voltage window of 3 V to 4.2 V, which can exceed the capacity of 25.57 mAh g−1 for porous carbon without heteroatom doping at the current density of 0.1 A g−1. Furthermore, the as-developed lithium-ion capacitor possesses an outstanding electrochemical performance (80.57 Wh kg−1 at 135 W kg−1 and 36.77 Wh kg−1 at 2.7 kW kg−1). This work can provide a new avenue to design cathode materials with a highly appreciable capacity and highly compatible kinetic mechanism, further developing high-performance lithium-ion capacitors.