Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
Key Laboratory of Spin Electron and Nanomaterials of Anhui Higher Education Institutes, Suzhou University, Suzhou 234000, China.
J Colloid Interface Sci. 2021 Jun;591:139-147. doi: 10.1016/j.jcis.2021.02.013. Epub 2021 Feb 8.
The parasitic reactions leading to capacity fading and charge loss remain a serious issue for capacitive deionization (CDI). NaTi(PO) (NTP) has recently emerged as a promising faradaic cathode in hybrid CDI (HCDI) with high Na uptake capacity and good Na selectivity, but it is still challenged by serious parasitic reactions. Although the irreversible faradaic reactions on carbon electrode are raising growing attention in CDI research field, the parasitic reactions on faradaic materials are seldom studied in HCDI by now. In this work, we evaluated the parasitic reactions of NTP-reduced graphene oxide (rGO) electrode in both three-electrode mode and full-cell HCDI mode. By using deaired electrolyte, the coulombic efficiency of NTP-rGO is significantly enhanced from 75.0% to 98.2% in 3rd cycle, and the capacity retention rate is promoted from 37.5% to 80.3% at the low current density of 0.1 mA g in 100 cycles, suggesting that electrochemical reduction of oxygen and its derived reactions are the main parasitic reactions in NTP-based HCDI. In full-cell HCDI desalination tests, by introducing cation exchange membrane to block the penetration of dissolved oxygen, the parasitic reactions and pH fluctuations are successfully suppressed. The study here provides an insight into understanding and suppressing the parasitic reactions in HCDI, and should be of value to the development of efficient and stable HCDI for practical applications.
对于电容去离子（CDI）而言，导致容量衰减和电荷损失的寄生反应仍然是一个严重的问题。NaTi(PO)（NTP）最近作为混合电容去离子（HCDI）中的一种很有前途的法拉第阴极出现，具有高钠吸收能力和良好的钠选择性，但它仍然受到严重的寄生反应的挑战。尽管在 CDI 研究领域，碳电极上不可逆的法拉第反应引起了越来越多的关注，但到目前为止，在 HCDI 中对法拉第材料的寄生反应的研究还很少。在这项工作中，我们评估了 NTP-还原氧化石墨烯（rGO）电极在三电极模式和全电池 HCDI 模式下的寄生反应。通过使用除气电解质，NTP-rGO 的库仑效率在第 3 个循环中从 75.0%显著提高到 98.2%，在 100 个循环中在低电流密度 0.1 mA g 时的容量保持率从 37.5%提高到 80.3%，表明电化学还原氧气及其衍生的反应是 NTP 基 HCDI 中的主要寄生反应。在全电池 HCDI 脱盐测试中，通过引入阳离子交换膜来阻止溶解氧的渗透，成功抑制了寄生反应和 pH 值波动。本研究深入了解了 HCDI 中寄生反应的抑制，这对于开发高效稳定的 HCDI 应用具有重要意义。
