Lithium-Seawater Battery for Backup Power on Underwater Vehicles

Background:

Extremely high energy density batteries are needed for underwater electric ships such as unmanned submarines and naval observatories.

Technology Overview:

The lithium-seawater battery is made of two compartments: the anode compartment, which encloses the metal in non-aqueous electrolyte, and the cathode compartment, which contains a porous and electrically conductive material and seawater.  A solid-state metal-ion conductive membrane is used to separate the two compartments. Inlets and outlets for seawater flow channels are installed in the cathode compartment and a mechanical pump is used to control and pump seawater into the compartment. The theoretical energy density of a Li-seawater flow battery is about 11.6 kWh/kg while the cost for replacing the lithium in the anode is about $1.2/kWh.  This makes the volumetric energy density of lithium-seawater flow battery about 2 kWh/L or 2,000 kWh/m^3, which is 0.0005 m^3/kWh.

Advantages

The lithium-seawater battery can deliver over specific energy of 4,000 Wh/kg, which is much greater than that of any electrochemical energy storage systems including hydrogen fuel cells.

Applications:

Emergency backup power on underwater vehicles or other naval equipment

Intellectual Property Summary:

PCT/US2023/060788 filed January 17, 2023

Stage of Development:

TRL 2

Licensing Status:

Available for license or collaboration.