Unraveling HCPs-derived porous carbon: Synthesis, pore formation and rapid potassium-ion storage

Constructing porous structured carbon anode materials is widely acknowledged as an effective strategy for enhancing the rapid storage of potassium-ions. However, limited progress remains in understanding the relationship between the pore structure of carbon anode materials and potassium-ion storage, impeding the development of high-performance potassium storage carbon anodes. Herein, hypercrosslinked polymers (HCPs) with varying pore structures were synthesized by modulating the degree of crosslinking of monomers. A series of HCPs-derived porous carbons (PCs) were prepared via direct pyrolysis method. The structure-activity relationship between the PCs and potassium-ion storage was studied. It was found that the microporous structure of HCPs originated from the crosslinking of monomers by the crosslinking agent (formaldehyde dimethyl acetal, FDA). While the mesoporous structure resulted from further crosslinking of basic structural units. The porous carbon obtained through direct pyrolysis kept the porous structure of the precursor, which provided active sites for rapid adsorption of potassium-ions. The micropore volume played an important role in enhancing K+ storage. Consequently, the DCPPC-600 electrode, with optimal structure, exhibited excellent reversible capacity (247 mAh g- 1, after 200 cycles) and rate performance. Furthermore, the potassium-ion hybrid capacitor (PIHC) based on the optimized DCPPC-600 anode delivered high energy density of 137 Wh kg- 1 at power density of 409 W kg- 1 which was stable after 10,000 cycles at 1 A g- 1. This study contributes to the rational design of PC anodes and offers insights into the engineering of pore structures in carbon materials for rapid potassium-ion storage.