Regulating and Unraveling Electrochemical Behavior of Hierarchically-Densifying Mesoporous Apocynum Carbon for High performance Supercapacitor

Abstract

The commercial carbon-based supercapacitor with high power ability (~5 kW kg⁻¹) is still unable to fulfill the superhigh power requirement of specific power-type equipments (>20 kW kg⁻¹), such as rail transit facilities, electromagnetic and laser equipment. To unravel the structure-activity relationship and electrochemical behavior of power-type densifying carbon is a key to overcome the contradiction of the suitable mesoporous ratio and highly-densifying features toward the superhigh power requirement. Here, we built the hierarchically-densifying mesoporous apocynum carbon (HDMC) with optimized mesoporous ratio by hierarchical activation method. More importantly, both the isothermal desorption/adsorption and high-pressure mercury intrusion porosimetry methods were employed to synergistically uncover the microscopic surface carbon network stacking mechanism and the macroscopic carbon skeleton densification assembly mechanism. The highly-densifying skeleton features and high mesoporous ratio properties were proved to be co-existed in HDMC, which is in favour of rapidly ion/electron transferring toward electrochemically-improving power behavior of HDMC. A combination of high tap density (0.387 g cm⁻³) and ideal microporous-mesoporous system (23.1 % proportion of mesoporous) have taken this HDMC to provide a super-high power density (33.5 kW kg⁻¹) and a high volume power density (9.37 kW L⁻¹) for HDMC-based supercapacitor, more than those of commercial YP-50F (14.9 kW kg⁻¹ @ 4.63 kW L⁻¹). Therefore, this work provides a synergistic strategy to incorporate the properties of mesoporous and densifying, and reveals its electrochemical behavior toward the further application of power-type supercapacitors.