The invention discloses a green cycle process for preparing an
activated carbon material for supercapacitors by using rice husks, and belongs to the technical field of comprehensive utilization of resources and electrochemical supercapacitors. The method comprises the following steps: carbonizing rice husks under the protection of
inert gas so as to obtain a carbonized product, adding alkali into the carbonized product, and sequentially activating, washing, filtrating and
drying so as to obtain high-specific-
capacitance rice
husk charcoal; adding
hydrochloric acid into filtrate for acidifying, and sequentially aging, filtrating, washing and
drying so as to obtain nano-silica; carrying out
impurity removal, concentration, primary refining, secondary refining and
electrolysis on the filtrate so as to obtain dilute alkali liquor, evaporating and crystallizing the dilute alkali liquor so as to obtain alkali, taking the obtained alkali as an activator used in the activation process, and taking water obtained in the process of
evaporation as water for washing, so that the cyclic utilization of alkali and water is realized. According to the invention,
capacitance charcoal capable of being used for the supercapacitors is prepared by using cheap rice husks;
silicon-containing waste liquid can be converted into nano-silica, so that the green conversion of high-value-added rice husks is realized, therefore, the green cycle process has a high economic benefit.