The stack configuration in flow-electrode capacitive deionization (FCDI) has been verified to be an attractive and feasible strategy for scaling up the desalination process. However, challenges still exist when attempting to simultaneously improve the desalination scale and the cell configuration. Here, we describe a novel stack FCDI configuration (termed a gradient FCDI system) based on a membrane-current collector assembly, in which the charge neutralization enables the in situ regeneration of the flow electrodes in the single cycle operation, thereby realizing a considerable increase in the desalinating performance. By evaluating standardized metrics such as the salt rejection, productivity (P), average salt removal rate (ASRR), energy-normalized removed salt (ENRS), and TEE, the results indicated that the gradient FCDI system could be a performance-stable and energy-efficient alternative for scale-up desalination. Under optimal operating conditions (carbon content = 10 wt %, feed salinity = 3000 mg L^–1, cell voltage = 1.2 V, and productivity = 56.7 L m^–2 h^–1), the robust desalination performance (ASRR = 1.07 μmol cm^–2 min^–1) and energy consumption (ENRS = 7.8 μmol J^–1) of the FCDI system with a desalination unit number of four were verified at long-term operation. In summary, the stacked gradient FCDI system and its operation mode described here may be an innovative and promising strategy capable of enlarging the scale of desalination while realizing performance improvement and device simplification.

中文翻译：

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基于膜集流器的流动电极电容去离子系统：一种用于扩大海水淡化的新型烟囱配置

流动电极电容去离子 (FCDI) 中的堆栈配置已被证实是一种有吸引力且可行的扩大海水淡化过程的策略。然而，当试图同时改善海水淡化规模和电池配置时，挑战仍然存在。在这里，我们描述了一种基于膜电流收集器组件的新型堆叠 FCDI 配置（称为梯度 FCDI 系统），其中电荷中和使单循环操作中的流电极原位再生，从而实现了显着增加在海水淡化方面。通过评估标准指标，例如脱盐率、生产率 ( P)、平均脱盐率 (ASRR)、能量归一化脱盐 (ENRS) 和 TEE，结果表明梯度 FCDI 系统可以成为规模化脱盐的性能稳定且节能的替代方案。在最佳操作条件下（碳含量 = 10 wt %，进料盐度 = 3000 mg L ^–1，电池电压 = 1.2 V，生产率 = 56.7 L m ^–2 h ^–1），强大的脱盐性能（ASRR = 1.07 μmol cm ^–2 min ^–1 ) 和能耗 (ENRS = 7.8 μmol J ^–1) 的 FCDI 系统的脱盐装置数量为 4，在长期运行中得到验证。总之，这里描述的堆叠梯度 FCDI 系统及其运行模式可能是一种创新且有前景的策略，能够在实现性能改进和设备简化的同时扩大淡化规模。