HIGH SPECIFIC CAPACITANCE ACTIVATED CARBON FOR ELECTROCHEMICAL CAPACITORS PREPARED FROM LIGNITE BY KOH ACTIVATION

摘要

Electrochemical capacitors (ECs) are promising energy storage devices with high power density, long cycle performance and friendliness to environment [1], and they have attracted great interest because of their possible usage in power sources for electric vehicles [2]. Among various available candidates of electrode materials for ECs, activated carbon (AC) is used most frequently due to its high specific surface area, well-developed microstructure, good conductivity, excellent physicochemical stability and cost-effective [1-4]. It has been proven that electrochemical behaviors of ECs are strongly affected not only by specific surface area of electrode materials, but also by other natures of AC such as pore size distribution, surface functional groups and electronic conductivity [5]. Therefore, AC with high surface area, suitable pore structure and proper surface chemistry are expected to be applied as excellent electrode materials to develop ECs with high performance. Coal is known as one of the most conventional carbonaceous precursors for the preparation of AC, and about 70% of AC was prepared from it in China. However, there are rare reports on AC based on low rank coal with excellent capacitive performance.