Nanotechnology scientists are working on a sodium-oxygen, seawater battery
a promising alternative to Lithium
Research into battery improvements has traditionally focused on Lithium as a necessary component. As a 2015 Nature report states:
"... Rechargeable metal–oxygen batteries are very attractive owing to their reliance on molecular oxygen, which forms oxides on discharge that decompose reversibly on charge. Much focus has been directed at aprotic Li–O2 cells, but the aprotic Na–O2 system is of equal interest because of its better reversibility."
Indeed, the other problem with Lithium is that as a rare earth element, it can be increasingly expensive. It also has a relatively small window when it comes to operational safety.
Which brings us to nanotechnology-based options that use seawater as the catholyte — where "catholyte" is a fancy way of saying an cathode + electrolyte combined.
From a recent release of the ACS Applied Materials & Interfaces publication:
"In batteries, the electrolyte is the component that allows an electrical charge to flow between the cathode and anode. A constant flow of seawater into and out of the battery provides the sodium ions and water responsible for producing a charge. The reactions have been sluggish, however, so the researchers wanted to find a way to speed them up."
And the scientists briefly summarize their method:
"We applied porous cobalt manganese oxide (CMO) nanocubes as the cathode electrocatalyst in rechargeable seawater batteries, which are a hybrid-type Na–air battery with an open-structured cathode and a seawater catholyte. The porous CMO nanocubes were synthesized by the pyrolysis of a Prussian blue analogue, Mn3[Co(CN)6]2·nH2O, during air-annealing, which generated numerous pores between the final spinel-type CMO nanoparticles. The porous CMO electrocatalyst improved the redox reactions, such as the oxygen evolution/reduction reactions, at the cathode in the seawater batteries. "