预嵌锂硬碳和软碳用于锂离子电容器负极的比较研究（英文）

A Comparative Study of Pre-Lithiated Hard Carbon and Soft Carbon as Anodes for Lithium-Ion Capacitors

锂离子电容器是一种应用前景广阔的电化学储能器件.目前,活性炭作为锂离子电容器正极被广泛使用.然而,锂离子电容器负极却有多种不同选择,如硬碳和软碳等碳材料.本文使用两种具有不同结构和电化学特性的硬碳和软碳材料作为锂离子电容器负极,进行了对比研究.研究表明,软碳相比于硬碳有更好的电子导电性和更高的可逆容量.通过在电流范围0.1～12 A·g^(-1)下进行充放电测试,分别研究了两种碳基电极在不同涂覆厚度下的倍率性能.结果显示,硬碳电极在大电流下有更好的倍率特性.然后,以活性炭为正极,预嵌锂的硬碳和软碳为负极,锂片为锂源和参比电极,分别组装了三电极软包锂离子电容器.根据三电极充放电测试,分别研究了不同预嵌锂量的硬碳和软碳所组装的锂离子电容器的电化学性能.结果表明,合适的负极预嵌锂容量可以提升锂电容的能量密度、功率密度和循环稳定性.最后,大容量硬碳和软碳基软包锂离子电容器被分别组装,软碳基锂电容实现了最高的能量密度21.2 Wh·kg^(-1)(基于整个器件质量),硬碳基锂电容实现最高的功率密度5.1 kW·kg^(-1).

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.