Comparative study of the power performance for advanced Li-ion capacitors with various carbon anodes

In recent years, an increased attention has been focused on Li-ion capacitors (LICs) which are high power hybrid devices. Various carbon materials (hard carbon (HC), soft carbon (SC) and graphite) have been investigated for use as the negative electrodes for LICs. The rate capabilities are compared by half cells with carbon anode as working electrode and lithium foil as counter electrode, and by LIC full cells with test current density up to 20 mA cm^-2. It is found that the LIC with HC at 20 mA cm^-2 could be maintained up to 72.5% of that at 0.5 mA cm^-2, which is the best power performance among all the carbon materials. The Scanning electron microscopy (SEM) images, surface area and the pore size distribution are also studied and compared for the various carbon anode materials.