Integrated Performance Metrics of Porous Carbon Toward Practical Supercapacitor Devices

The scientific communities in both academia and industry are devoted to increasing energy density of supercapacitor devices, including investigating the relationship between carbon structure and capacitance of various activated carbon (AC) materials. However, most reported capacitance values are measured solely at the material level, which are difficult to directly translate into achievable energy densities for practical supercapacitor devices. In this work, we assemble supercapacitor pouch cells to reveal the insight relationships between the capacitance and porosity of AC materials and the optimal amount of electrolyte at the device level. Concurrently, a guidance on the required amount of electrolyte is provided, indicating that both the specific capacitance and porosity of AC materials collectively determine the energy density of a practical device (E_device). Furthermore, we develop a computational E-tool for directly predicting E_device at an early stage of material-level electrochemical testing. Finally, we propose a new descriptor (η) that incorporates both the capacitance and porosity parameters of AC materials, which displays a linear relationship with E_device. This study provides a reliable E-tool and η for accelerating the development of advanced charge storage mechanisms and carbon materials for practical supercapacitor devices.