Batteries in desalination: A review of emerging electrochemical desalination technologies

Remarkable progress has been achieved to enhance the performance of electrochemical desalination technologies. Desalination batteries are promising due to their ability to simultaneously desalinate water and generate energy. A typical desalination battery consists of rechargeable high-capacity Na- and Cl-storage electrodes that remove ions during charging and release them during discharging. This technology works at low voltages and does not require chemicals, high-pressure pumps, or thermal heaters. Despite the existence of studies focusing on desalination batteries, a notable research gap persists regarding the assessment of performance characteristics, comparison of the various desalination battery designs, evaluation of energy consumption, and the exploration of the potential and limitations of desalination batteries. This highlights the need for a comprehensive review to address these key aspects. The goal of this work was to address these points by shedding light on the fundamentals, principles, and main findings related to desalination batteries to-date. Four main types of desalination batteries are surveyed: membrane-free, rocking chair, redox flow, and metal-air. Emphasis is given on energy considerations, as the energy consumption of desalination technologies has been a significant challenge for decades. Finally, research directions for further desalination battery developments are discussed related to both challenges and opportunities in the field.