Hierarchically nitrogen-doped mesoporous carbon nanospheres with dual ion adsorption capability for superior rate and ultra-stable zinc ion hybrid supercapacitors

Abstract

Although significant progress has been achieved in developing high energy aqueous zinc ion hybrid super-capacitors (ZHSCs), the sluggish diffusion of zinc ion (Zn2+) and unsatisfactory cathodes still hinder their energy density and cycling life span. This work demonstrates the use of nitrogen-doped mesoporous carbon nanospheres (NMCSs) with appropriately hierarchical pore distribution and enhanced zinc ion storage capability for efficient Zn2+ storage. The as-prepared aqueous ZHSC delivers a significant specific capacity of 157.8 mA h g−1, a maximum energy density of 126.2 W h kg−1 at 0.2 A g−1, and an ultra-high power density of 39.9 kW kg−1 with a quick charge time of 5.5 s. Furthermore, the ZHSC demonstrates an ultra-long cycling life span of 50,000 cycles with an exciting capacity retention of 96.2%. More interestingly, a new type of planar ZHSC is fabricated with outstanding low-temperature electrochemical performance, landmark volumetric energy density of 31.6 mW h cm−3, and excellent serial and parallel integration. Mechanism investigation verifies that the superior electrochemical capability is due to the synergistic effect of cation and anion adsorption, as well as the reversible chemical adsorption of NMCSs. This work provides not only an innovative strategy to construct and develop novel high-performance ZHSCs, but also a deeper understanding of the electrochemical characteristics of ZHSCs.