• First report of a lithium-ion battery cathode as a deionization electrode for desalination.

• A novel approach to suppress manganese dissolution by exposing the (111) facet is proposed.

• Excellent desalination performance by the LiMn₂O₄/C cathode. The material achieves an ultrahigh desalination capacity of 117.3 mg g⁻¹ at 1.0 V and a longer cycle life (200 cycles without capacity decay) with minor manganese dissolution during the cycling test in 10 mM aqueous LiCl solution.

Battery materials as emerging capacitive deionization electrodes for desalination have better salt removal capacities than traditional carbon-based materials. LiMn₂O₄, a widely used cathode material, is difficult to utilize as a deionization electrode due to its structural instability upon cycling and Mn dissolution in aqueous-based electrolytes. Herein, a facile and low-cost ball-milling routine was proposed to prepare a LiMn₂O₄ material with highly exposed (111) facets. The prepared electrode exhibited relatively low dissolution of Mn during cycling, which shows its long cycle stability. In the hybrid capacitive deionization system, the LiMn₂O₄/C electrode delivered a high desalination capacity of 117.3 mg g⁻¹ without obvious capacity decay at a voltage of 1.0 V with a 20 mM initial salt concentration. In addition, the exposed (111) facets significantly alleviated Mn ion dissolution, which also enhanced the structural steadiness.

• 锂离子电池阴极作为脱盐去离子电极的首次报告。

• 提出了一种通过暴露 (111) 面来抑制锰溶解的新方法。

• LiMn ₂ O ₄ /C阴极具有优异的脱盐性能。该材料在 1.0 V 时实现了 117.3 mg g ^-1的超高脱盐容量和更长的循环寿命（200 次循环无容量衰减），在 10 mM LiCl 水溶液中的循环测试期间锰溶解较少。

电池材料作为新兴的用于海水淡化的电容去离子电极，比传统的碳基材料具有更好的除盐能力。LiMn ₂ O ₄是一种广泛使用的正极材料，由于其在循环过程中的结构不稳定以及锰在水基电解质中的溶解，因此难以用作去离子电极。在此，提出了一种简便且低成本的球磨程序来制备具有高度暴露 (111) 面的 LiMn ₂ O _4材料。制备的电极在循环过程中表现出相对较低的 Mn 溶解，这表明其具有长循环稳定性。在混合电容去离子系统中，LiMn ₂ O ₄/C 电极提供了 117.3 mg g ^-1的高脱盐容量，在 1.0 V 的电压和 20 mM 的初始盐浓度下没有明显的容量衰减。此外，暴露的 (111) 面显着减轻了 Mn 离子溶解，这也增强了结构稳定性。