Isostatic pressure-assisted nanocasting preparation of zeolite templated carbon for high-performance and ultrahigh rate capability supercapacitors

Abstract

Increasing charge storage and fast charging capability has been a long-standing challenge for supercapacitors. In this study, a novel, facile high isostatic pressing-assisted nanocasting method was developed to produce zeolite templated carbon (ZTC) with excellent supercapacitance performances. There is a strong positive correlation between the isostatic pressure imposed on the carbon source and the surface area, nitrogen doping and electrochemical properties of the ZTC material. Consequently, the ZTC-P300 (300 MPa pressure denoted as P300, which is the maximum operation pressure) electrode with a narrowly distributed interconnected micropore channel system shows the best supercapacitor performance, i.e. remarkable specific capacitance of 253 F g⁻¹ (areal capacitance: 759 mF cm⁻²) at a current density of 1.25 A g⁻¹ in 6 M KOH electrolyte, high charging capability of 163.5 F g⁻¹ at an ultrahigh current density of 62.5 A g⁻¹, excellent cycling stability with only 5% loss in capacitance after 10 000 cycles (at 5 A g⁻¹), and relatively high energy density of 7.5 W h kg⁻¹ at a power density of 625 W kg⁻¹. Its outstanding capacitive performance is attributed to its high large surface area (2169 m² g⁻¹), proper pore size (average pore size of 1.2 nm), and high content of doped nitrogen (6.27%). Significantly, the electrochemical analyses show that the ZTC porous structure containing optimum micropores allows efficient ion diffusion and charge transfer, resulting in an excellent energy storage performance and rate capability.