Cheese-like hierarchical porous carbon material with large specific surface area derived from red dates for high performance supercapacitors

Red dates are rich in porous structure inside, and the carbonization process can easily inherit unique constructions, which is beneficial to the rapid transmission of ions. The specific surface area (SSA) and pore structure are the key factors that determine the energy storage performance of carbon material supercapacitors. In this paper, hierarchical porous carbon materials (RDKC-4-800) with cheese-like microstructure based on red dates were prepared by two steps of hydrothermal pre-carbonization and KOH carbonization activation. The obtained materials have a rich hierarchical pore structure and large SSA (1115.7 m2 g−1), which is conducive to ion and electron transport and contribute to excellent electrochemical properties. Electrochemical tests indicate a high specific capacitance value of 341.9 F g−1 for the material at a current density of 0.5 A g−1. The assembled supercapacitors exhibited an energy density of 10.9 W h kg−1 and a power density of 124.93 W kg−1, outperforming many biomass carbon supercapacitors studies under similar conditions reported in the literature. After 30,000 charge and discharge cycles at a current density of 5 A g−1, the capacitance retention rate is 81.29 % and the coulombic efficiency is 99.67 %. This study provides an efficient and concise method to prepare red dates porous carbon materials and demonstrates that red dates biomass can be effectively reused in the field of supercapacitors.