Pyrolytic carbons from acid/base-treated rice husk as lithium-insertion anode materials

Abstract

The effects of hydrochloric acid and sodium hydroxide as leachants on the lithium-insertion properties of pyrolytic carbons prepared from rice husk are presented. All the disordered carbonaceous products had interlayer spacings (d002) of more than 3.7 Å, with values decreasing with an increase in the concentration of the leachant. The values of the H/C ratio and the R-parameter, the reciprocal of which is a measure of the number of non-parallel single layers of carbon, also diminished with an increase in the concentration of NaOH. An increase in the alkali concentration was found to improve the porosity of the carbons, as evidenced by the Brunauer–Emmett–Teller (BET) surface area data. An interaction of these factors determines the observed capacities of the carbon products. The highest insertion and deinsertion capacities were observed with the carbon obtained from rice husk treated with 0.3 M NaOH, the values being 819 and 463 mAh/g, respectively.