Extended life.


Introducing the first-ever seawater-activated lithium battery. The highest energy density in the history of batteries.

PolyPlus developed the first seawater-activated lithium batteries by coupling the PLE with water-activated cathodes.

During operation, the batteries are open to the seawater environment. The Li-water battery is safe, compact and has virtually zero self-discharge. 


A Battery That Runs on Seawater

Protected Lithium Electrode (PLS)

12 years of research and development and 5 years of manufacturing have led to the first battery based on solid electrolyte membranes.


Using seawater, this revolutionary technology has zero self-discharge and exceptional energy density. It is extremely safe, environmentally benign and a catalyst in replacing toxic batteries.


The World’s First
Seawater-Activated Lithium Battery



A battery that runs on seawater, PolyPlus’ Li-Seawater batteries combine the Protected Lithium Electrode (PLS) with seawater as the cathode active species. Lithium seawater batteries provide key advantages over other primary batteries (such as lithium thionyl chloride) including a 10X increase in energy density along with inherent safety. This revolutionary technology has zero self-discharge and exceptional energy density. Depending on size and form factor, the batteries can reach energy densities of 2000 Wh/kg and >1500 Wh/l, which is an order of magnitude greater than competing technologies, including Li-ion. PolyPlus’ Li/SWB represents a game changing technology for long endurance underwater/subsea applications.

The PolyPlus Seawater Advantage

Ultra-lightweight, Compact, Underwater Energy Source

PolyPlus’ Li-Seawater batteries can pack a large amount of energy into a small amount of space, and are close to neutral buoyancy.

Long Lifetime

The combination of exceptional energy density and zero self discharge, makes PolyPlus Li-Seawater batteries ideal for long duration underwater applications.


For deep ocean use, the Li-Seawater batteries do not need to be housed in bulky, expensive, protective pressure vessels. PLEs have been pressure tested at 10,000 psi in hydraulic fluid and 2500 psi in salt water with no adverse effect on subsequent electrochemical performance.

Property Protected

With more than 200 patents granted and pending, PolyPlus has an extensive patent portfolio that includes broad coverage of our glass protected lithium batteries.


Pushing the Limits of What’s Possible

Interest in batteries for marine applications is growing rapidly, largely due to the advent of autonomous vehicles for oceanographic, commercial, and military applications. The extremely high energy density of PolyPlus Li-Seawater batteries combined with their safety make them a compelling choice for marine applications needing the ultimate in energy density.

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