Rechargeable Seawater Battery

This study demonstrates the feasibility of a rechargeable sweater battery that use seawater and its contents of chemicals as the anode and cathode materials for the first time. Na-ions were harvested from the seawater by charging the battery, and the harvested Na-ions were discharged with water (or oxygen dissolved in the seawater) as oxidants to produce an electricity. Seawater provided both chemicals of the anode (Na metal) and cathode (O₂) materials for the proposed battery, and it is rechargeable. From the discharge voltage (~2.9 V) and charge voltage (~4.0 V) at the first cycle, ~73% of the voltage efficiency was observed. When the seawater battery was built by using a hard carbon as the anode and NASICON as the solid electrolyte, a good cycle life performance was observed up to 40 cycles.