Ginkgo leaf nanoarchitectonics-derived carbon materials containing ultrathin carbon nanosheets for high-performance symmetric supercapacitors

Abstract

The carbon material derived from ginkgo leaves is composed of stacked ultra-thin carbon nanosheets. To this end, carbon materials containing ultra-thin carbon nanosheets were prepared by using ginkgo leaf as a carbon source and KCl as a stripping agent. The study found that the formation of ultra-thin carbon nanosheets depends on the structure of the biomass, and only Cl⁻ in KCl produces a stripping effect, independent of K⁺. The composition and structure of carbon materials are closely related to the mass of KCl, and different KCl mass can make carbon materials have different specific surface area and heteroatom content. When 12 g KCl was added, the prepared GCK-12 had the highest heteroatom content and medium specific surface area. Electrochemical test results show that the electrochemical performance of KCl-modified carbon materials is higher than that of unmodified carbon materials, indicating that ultra-thin carbon nanosheets provide more active sites for electrodes. Among them, GCK-12 has the best electrochemical performance, and the specific capacitance is 240 F g⁻¹ when the current density is 1 A g⁻¹. Above or below 12 g, the specific capacitance will be reduced. The symmetric supercapacitors assembled with GCK-12 have an energy density of up to 15 Wh kg⁻¹, which is superior to previously reported biomass carbon materials. By analyzing the relationship between the structure and electrochemical performance of GCK-12, it can be seen that increasing the heteroatom content is more beneficial to improve the electrochemical performance than increasing the specific surface area. This work not only provides a new method for the preparation of ultra-thin carbon nanosheets, but also provides a new idea for the design and synthesis of high-performance carbon materials.