Acid-Alkali Deep Deashing and Alkali Activation of Coal Gasification Fine Slag for Supercapacitive Electrode Application

Nowadays, coal gasification fine slag (CGFS) generated during the coal gasification process has become difficult to treat bulk solid waste. CGFS contains high levels of residual carbon, which is difficult to recycle due to the tight binding of minerals with residual. In our study, the carbon source of active carbon (P-AC) was obtained by the molten-caustic leaching (MCL) method, in which alkaline leaching solution can be further used as a ceramic precursor. Subsequently, the KOH activation method was used to prepare the activated carbon (AC) electrode materials. The deashing conditions and activation parameters were optimized carefully. The results indicate that the AC-800 electrode material exhibits excellent specific capacitance and cycle stability; the main reason for good performance is the hierarchical porous structure of AC-800 that not only provides the path for ion diffusion but also strengthens the fluidity of electrolyte inside the material. This paper offers an effective method to enhance the added value of CGFS by a fluoride-free ash removal process.