A Comparative Study of Pre-Lithiated Hard Carbon and Soft Carbon as Anodes for Lithium-Ion Capacitors
LI Zhao;SUN Xian-zhong;LIU Wen-Jie;ZHANG Xiong;WANG Kai;MA Yan-wei;Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences;University of Chinese Academy of Sciences;
Lithium-ion capacitor(LIC) has emerged to be one of the most promising electrochemical energy storage devices.Presently, activated carbon(AC) is the mostly used cathode material for LIC. Nevertheless, various carbonaceous materials can be used as anode materials, such as hard carbon(HC) and soft carbon(SC). Therefore, HC and SC with different structural and electrochemical characteristics have been investigated as the anode materials of LICs in this work. Compared with the HC electrode, the SC electrode showed higher electronic conductivity and reversible capacity. The rate capabilities of the two carbonaceous materials as a function of coating thickness have been evaluated using a wide range of current densities(0.1 ～ 12 A·g~(-1)). It reveals that the HC electrode exhibited better rate capability. The three-electrode LIC pouch cells have been assembled by using an AC cathode and various carbonaceous anodes with different pre-lithiation capacities. The potential swings and the IR drops of HC-and SC-based LICs have been studied. For both of the LIC systems, the appropriate pre-lithiation capacity could improve electrochemical performances, i.e., energy density, power density and cycling stability. Finally, the large-capacity LIC pouch cells of around 97 m Ah were fabricated. The AC//SC LIC achieved the highest energy density of 21.2 Wh·kg~(-1), while the AC//HC LIC achieved the highest power density of 5.1 kW·kg~(-1) based on the total weight of the device.