Two series of activated carbons were prepared by chemical activation of three different kinds of agricultural waste: cherimoya (Annona cherimola), fig (Ficus carica) and olive (Olea europaea) woods. KOH and H3PO4 were selected as activating agents. The main differences between these trees are their growth rate and the hardness of the wood. Due to these differences, distinct pore structure, surface areas and chemical composition were found for the different activated carbons prepared. Phosphoric acid-activated samples present a high ash content due to the phosphate formation during the activation process. KOH-activated samples are mainly microporous materials with high surface area and pore volumes. On the contrary, when H3PO4 was used as activating agent, activated carbons are meso-microporous materials. Ash content and micropore structure are limiting factors for the application of activated carbons as electrodes for supercapacitors. The best performance corresponds to KOH-activated samples with high capacitance and energy and power densities. The stability of the electrodes, evaluated by charge–discharge cycling, shows that the KOH-activated carbons have a high cyclic stability up to 12,000 cycles. For H3PO4 samples, the capacitance decreases due to their high ash content and the poor stability of the acidic surface groups.

中文翻译：

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通过用 H3PO4 和 KOH 化学活化作为电化学电容器电极的农业木材废料的价值

通过化学活化三种不同种类的农业废弃物制备了两个系列的活性炭： cherimoya (Annona cherimola)、无花果 (Ficus carica) 和橄榄 (Olea europaea) 木材。选择 KOH 和 H3PO4 作为活化剂。这些树木之间的主要区别在于它们的生长速度和木材的硬度。由于这些差异，制备的不同活性炭具有不同的孔结构、表面积和化学成分。由于在活化过程中形成磷酸盐，磷酸活化的样品呈现高灰分含量。KOH 活化的样品主要是具有高表面积和孔体积的微孔材料。相反，当使用 H3PO4 作为活化剂时，活性炭是中微孔材料。灰分含量和微孔结构是活性炭作为超级电容器电极应用的限制因素。最佳性能对应于具有高电容、能量和功率密度的 KOH 活化样品。通过充放电循环评估的电极稳定性表明，KOH 活性炭具有高达 12,000 次循环的高循环稳定性。对于 H3PO4 样品，由于其高灰分含量和酸性表面基团稳定性差，电容降低。表明 KOH 活性炭具有高达 12,000 次循环的高循环稳定性。对于 H3PO4 样品，由于其高灰分含量和酸性表面基团稳定性差，电容降低。表明 KOH 活性炭具有高达 12,000 次循环的高循环稳定性。对于 H3PO4 样品，由于其高灰分含量和酸性表面基团稳定性差，电容降低。