Intercalative deionization (IDI) uses two cation intercalation electrodes separated by an anion exchange membrane in a symmetric cell design that has the potential to deliver electrochemically desalinated water in an energy- and water-efficient way. Here, we define and measure metrics to describe the performance and lifetime of IDI cells and compare them for NaCl and CaCl₂ feed solutions. With 20 mM NaCl, NiHCF/AEM/NiHCF flow cells achieve 10 mM average concentration change at a productivity of 20 l/h/m² and 5 mM average concentration change at 130 l/h/m². In both cases the cells are operated at a 3C current rate and consume ~30 Wh/m³ of energy. With 10 mM CaCl₂, the specific capacity and salt removal of IDI flow cells is ~4 times lower. NiHCF/NiHCF beaker cells with CaCl₂ electrolyte suffer from strong capacity fade, while the same cells with NaCl electrolyte achieve 500 cycles without any capacity fade. Our post-mortem analysis using X-ray diffraction, secondary electron microscopy, energy dispersive X-ray spectroscopy, synchrotron-based X-ray absorption spectroscopy and micro X-ray fluorescence mapping reveals that NiHCF dissolves upon repeated intercalation with Ca²⁺, releasing residual K⁺, Ni²⁺ and Fe(CN)₆³, which precipitates as a crystalline decomposition product on the electrodes. This side reaction deprives the active material NiHCF of charge compensating Fe, and thus accounts for the observed capacity fade.

插层去离子 (IDI) 在对称池设计中使用由阴离子交换膜隔开的两个阳离子插层电极，该电极有可能以节能和节水的方式提供电化学脱盐水。在这里，我们定义和测量指标来描述 IDI 电池的性能和寿命，并将它们与 NaCl 和 CaCl ₂进料溶液进行比较。使用 20 mM NaCl，NiHCF/AEM/NiHCF 流通池在 20 l/h/m ²的生产率下实现 10 mM 平均浓度变化，在 130 l/h/m ^{2 下实现}5 mM 平均浓度变化。在这两种情况下，电池都以 3C 的电流速率运行并消耗约 30 Wh/m ³的能量。含 10 mM CaCl ₂，IDI 流通池的比容量和除盐率低约 4 倍。使用 CaCl ₂电解质的NiHCF/NiHCF 烧杯电池容量衰减严重，而使用 NaCl 电解质的相同电池可实现 500 次循环而没有任何容量衰减。我们使用 X 射线衍射、二次电子显微镜、能量色散 X 射线光谱、基于同步加速器的 X 射线吸收光谱和显微 X 射线荧光图的验尸分析表明，NiHCF 在与 Ca ²⁺重复嵌入后溶解，释放出残留 K ⁺、Ni ²⁺和 Fe(CN) ₆ ³，在电极上作为结晶分解产物沉淀。这种副反应剥夺了活性材料 NiHCF 的电荷补偿 Fe，从而解释了观察到的容量衰减。