Amorphous carbon nanosheets suitable for deep eutectic solvent electrolyte toward cryogenic energy storage

The emerging deep eutectic solvent (DES) electrolyte has great potential in realizing commercial-scale appli-cation of electric double-layer capacitors (EDLCs) served in low temperature environment. That goal, however, rests with how to design the interface structure of electrode materials for well-matching with DES electrolyte. Herein, porous carbon nanosheets (PCNs) were obtained from coal tar pitch through Friedel-Crafts acylation reaction and melting salt intercalation process. The morphology, specific surface area and porosity of porous carbon nanosheets were regulated by tailoring the abundance of the dangling-bonds grafted on the CTP mole-cules. Profiting from the large specific surface area, suitable pore structure and good two-dimensional structure to provide more active sites and enhance ion transport capacity, the PCNs-0.10 delivers a maximal specific capacitance of 504F g+1 at 0.1 A g+1, which is overmatch than most of previously reported for other carbon materials. As-assembled symmetrical EDLCs using K+ DES electrolyte, can be assembled to work at-40 degrees C to 75 & DEG;C and exhibit satisfactory energy density. The strategy proposed here has opened a new way for exploring the large-scale preparation of electrode materials suitable for ultra-low temperature capacitors.