Effects of structure of heat-treated pitch precursors on electrochemical properties of pitch-based activated carbons

Activated carbons (ACs) prepared from heat-treated pitch precursors with KOH activation are used to fabricate electrodes for electric double-layer capacitors. The electrochemical properties of pitch-based ACs were investigated based on the structural differences between the pitch precursors prepared at different heat treatment temperatures. The high crystallite height of the pitch precursor before KOH activation resulted in improved porous structures having a high specific surface area and total pore volume, while the high crystallite width of the pitch precursors before KOH activation was responsible for the high micropore volume fraction. As a result, the A-HP1 and A-HP2, which were prepared from heat-treated pitch precursor, showed improved electrochemical properties due to the improved porous structures resulting from the high total pore volume fraction. In particular, A-HP1 has higher specific capacitance than A-HP2, because of the high micropore volume fraction of the former.

Graphical abstractSpecific surface area and the micropore volume of A-HP1 and A-HP2 prepared from heat-treated pitch precursor were higher than those of A-P. This can be attributed to the higher crystallite size of the initial heat-treated pitch that was used to prepare AC.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Preparation of activated carbons (ACs) from heat-treated petroleum pitch precursors. ► Heat treatment temperature for good electrochemical properties of pitch based ACs. ► Structural difference of heat-treated pitch leads to improvement of porous structure. ► Crystallite width of pitch has an effect on micropore structure after activation.