Rechargeable Seawater Battery Coupled to Solar Seawater Desalination With a Mutual Enhancement Effect

Rechargeable seawater battery (RSWB) is a promising candidate for low-cost energy storage while solar seawater desalination (SSD) can produce clean water from seawater, yet no attempts have been made to integrate them, preferably with a mutual enhancement effect. In this study, we report an ε-MnO₂ material with bifunctions of ion storage for RSWB and photothermal effect for SSD. The integration of RSWB and SSD leads to a mutual enhancement effect, in sharp contrast to traditional integrations. The ε-MnO₂ displays a high specific capacity of 265 mAh g^-1 for RSWB. When coupled with SSD, the specific capacity obviously increases, and meanwhile the seawater evaporation rate also increases substantially during the charge/discharge process. The mutual enhancement effect is attributed to the temperature increase in cathode caused by the photothermal effect of ε-MnO₂ and the weakened hydrogen-bonding interaction arising from the charge/discharge process. This work would provide new perspectives on energy storage and clean water production.