Highlights

?  NaxCoO2 as a model system to explore the effect of Na+/vacancy ordering

?  Na0.50CoO2 achieves a capacity and rate of 130.2 mg g?1 and 2.61 mg g?1 min?1.

?  High capacity is benefit from wilder reversible adjacent intermediate phases region.

?  High desalination rate depends on unique Na-ions ordering pattern of Row.

In this work, we used NaxCoO2 as a model system for the first time to explore the effect of Na+/vacancy ordering on desalination performance. An asymmetrical FDI device was developed where NaxCoO2 as the Faradic electrode material and AC act as the Cl-storage electrode material. For x = 0.50,this configuration yields an ultrahigh desalination capacity (130.2 mg g?1), an excellent charge efficiency (100%), and a superior desalination rate (2.61 mg g?1 min?1) in 1000 mg L?1 NaCl solution at 1.4 V. The experimental results reveal that the desalination capacity depends on the range of reversible adjacent intermediate phases region and the desalination rate is affected by the sodium ions mobility in the interlayer determined by the Na+/vacancy ordering pattern between the CoO2 slabs. The excellent desalination capacity and rate are encouraging.

https://www.sciencedirect.com/science/article/abs/pii/S0011916419315243?via%3Dihub