Hierarchically Porous Carbon Nanosheets from One-Step Carbonization of Zinc Gluconate for High-Performance Supercapacitors

Abstract

Supercapacitors, with high energy density, rapid charge-discharge capabilities, and long cycling ability, have gained favor among many researchers. However, the universality of high-performance carbon-based electrodes is often constrained by their complex fabrication methods. In this study, the common industrial materials, zinc gluconate and ammonium chloride, are uniformly mixed and subjected to a one-step carbonization strategy to prepare three-dimensional hierarchical porous carbon materials with high specific surface area and suitable nitrogen doping. The results show that a specific capacitance of 221 F g^-1 is achieved at a current density of 1 A g^-1. The assembled symmetrical supercapacitor achieves a high energy density of 17 Wh kg^-1, and after 50,000 cycles at a current density of 50 A g^-1, it retains 82% of its initial capacitance. Moreover, the operating voltage window of the symmetrical device can be easily expanded to 2.5 V when using Et₄NBF₄ as the electrolyte, resulting in a maximum energy density of up to 153 Wh kg^-1, and retaining 85.03% of the initial specific capacitance after 10,000 cycles. This method, using common industrial materials as raw materials, provides ideas for the simple preparation of high-performance carbon materials and also provides a promising method for the large-scale production of highly porous carbons.