NaTi₂(PO₄)₃-Ag electrodes based desalination battery and energy recovery

Desalination battery, consisting of sodium and chloride dual-ion electrochemical electrodes, is an aqueous energy storage device for the use of seawater deionization. Herein, a novel and stable rechargeable desalination cell is demonstrated based on such dual-ion electrochemical deionization technology, comprising of NaTi₂(PO₄)₃ anode and silver cathode in an aqueous NaCl electrolyte. During the charging process, sodium ions in electrolyte are electrochemically captured into NaTi₂(PO₄)₃ electrode while chloride ions are captured and reacted with silver electrode to form AgCl, whereas discharging causes the release of sodium and chloride ions from the corresponding electrodes. The distinct charge/discharge plateaus are located at 0.86 V/0.76 V. The stable capacity of 37.4 mAh/g is achieved for 200 cycles at a current density of 1000 mA/g, and the corresponding energy efficiency is up to 71.9%. The calculated energy consumption of 3.80 Wh/L is obtained with the energy recovery during discharge process for converting seawater to fresh water. We believe it will contribute greatly towards future energy saving seawater desalination technologies.