School of Material Science and Engineering, Jiangsu University, 301, Xuefu Road, Zhenjiang, Jiangsu 212013, China.
Molecules. 2019 Jul 16;24(14):2589. doi: 10.3390/molecules24142589.
The proton transfer mechanism on the carbon cathode surface has been considered as an effective way to boost the electrochemical performance of Zn-ion hybrid supercapacitors (SCs) with both ionic liquid and organic electrolytes. However, cheaper, potentially safer, and more environmental friendly supercapacitor can be achieved by using aqueous electrolyte. Herein, we introduce the proton transfer mechanism into a Zn-ion hybrid supercapacitor with the ZnSO aqueous electrolyte and functionalized activated carbon cathode materials (FACs). We reveal both experimentally and theoretically an enhanced performance by controlling the micropores structure and hydrogen-containing functional groups (-OH and -NH functions) of the activated carbon materials. The Zn-ion SCs with FACs exhibit a high capacitance of 435 F g and good stability with 89% capacity retention over 10,000 cycles. Moreover, the proton transfer effect can be further enhanced by introducing extra hydrogen ions in the electrolyte with low pH value. The highest capacitance of 544 F g is obtained at pH = 3. The proton transfer process tends to take place preferentially on the hydroxyl-groups based on the density functional theory (DFT) calculation. The results would help to develop carbon materials for cheaper and safer Zn-ion hybrid SCs with higher energy.
质子在碳阴极表面的转移机制被认为是提高离子液体和有机电解液的锌离子混合超级电容器（SCs）电化学性能的有效方法。然而，使用水性电解液可以实现更便宜、潜在更安全、更环保的超级电容器。在此，我们将质子转移机制引入到具有 ZnSO4 水性电解液和功能化活性炭阴极材料（FACs）的锌离子混合超级电容器中。我们通过控制活性炭材料的微孔结构和含氢官能团（-OH 和-NH 官能团），从实验和理论上揭示了这种方法对性能的增强作用。具有 FACs 的锌离子SCs 表现出 435 F g 的高电容和良好的稳定性，在 10000 次循环后容量保持率为 89%。此外，通过在低 pH 值的电解液中引入额外的氢离子，可以进一步增强质子转移效应。在 pH = 3 时，获得了最高的 544 F g 的电容。基于密度泛函理论（DFT）计算，质子转移过程倾向于优先发生在羟基上。这些结果将有助于开发更便宜、更安全、能量更高的锌离子混合超级电容器用碳材料。
