Capillary Evaporation on High-Dense Conductive Ramie Carbon for Assisting Highly Volumetric-Performance Supercapacitors

Conductive biomass carbon possesses unique properties of excellent conductivity and outstanding thermal stability, which can be widely used as conductive additive. However, building the high-dense conductive biomass carbon with highly graphitized microcrystals at a lower carbonization temperature is still a major challenge because of structural disorder and low crystallinity of source material. Herein, a simple capillary evaporation method to efficiently build the high-dense conductive ramie carbon (hd-CRC) with the higher tap density of 0.47 cm³ g^-1 than commercialized Super-C45 (0.16 cm³ g^-1 ) is reported. Such highly graphitized microcrystals of hd-CRC can achieve the high electrical conductivity of 94.55 S cm^-1 at the yield strength of 92.04 MPa , which is higher than commercialized Super-C45 (83.92 S cm^-1 at 92.04 MPa). As a demonstration, hd-CRC based symmetrical supercapacitors possess a highly volumetric energy density of 9.01 Wh L^-1 at 25.87 kW L^-1 , much more than those of commercialized Super-C45 (5.06 Wh L^-1 and 19.30 kW L^-1 ). Remarkably, the flexible package supercapacitor remarkably presents a low leakage current of 10.27 mA and low equivalent series resistance of 3.93 mΩ. Evidently, this work is a meaningful step toward high-dense conductive biomass carbon from traditional biomass graphite carbon, greatly promoting the highly-volumetric-performance supercapacitors.