Over the last two decades, LIB technology has been used in the defense sector for underwater applications such as conventional submarines, special force delivery vehicles, UUVs, and torpedoes. Despite wide use in a variety of applications, lithium-ion batteries can be described as a relatively immature energy storage technology. The Li-ion battery technology has improved recently, and has become a real emerging technology across a wide range of civil and defense applications.

Listed below are the key opportunities and threats of lithium-ion batteries for underwater opportunities, as identified by GlobalData.

A potential replacement for lead-acid batteries

LIBs are a potential replacement for lead-acid batteries as the main source of electrical power for submarines. Compared to lead-acid batteries, LIBs offer superior energy density, improved charge, and discharge dynamics and better overall operational life, typically lasting more than twice as long as lead-acid batteries.

All diesel-powered submarines use batteries to travel silently underwater. The batteries are charged by the diesel engine, which needs oxygen to run. This requires the submarine to surface, or at least snorkel, which exposes the periscope, an air intake, and an exhaust port above the surface of the water. With a LIB, the submarine can stay underwater much longer than with a lead-acid battery. The energy stored in the entire battery block could supply a small town for hours.

The LIBs are designed so that they can be installed in any submarine with slight technical adaptations and thus directly replace the lead-acid battery.

LIB safety regulations

In terms of fire risk, LIBs are currently encountering serious fire safety concerns in a variety of industries, including the consumer electronics, automotive, aviation, and marine sectors.

The International Air Transport Association released the first edition of an operator’s guidance document for mitigating the risk associated with lithium batteries, which came into effect in 2015. Similarly, the US Navy released its Lithium Battery Systems Navy Platform Integration Safety Manual in mid-2011 and continues to research improved safety for LIBs.

New battery technologies

Current LIBs rely on two essential metals – cobalt and nickel – that harm the people who mine them, as well as the environment. IBM has recently developed a new type of battery that’s free of cobalt, nickel, and other heavy metals, avoiding the environmental and humanitarian issues related to lithium-ion technology.

When optimised for performance, the battery has a higher power density than lithium-ion, meaning potentially smaller batteries that could be transformative for technology like electric aircraft.

In addition, the new battery independently developed by Tesla is a combination of dry battery technology and a supercapacitor. The combination of these two technologies has the potential to increase energy density, and hence driving range, as well as increase charging speed.

There are studies for developing solid-state battery technology. Today’s best-in-class LIB cells contain a liquid electrolyte. Solid-state batteries, which include a solid electrolyte instead of a liquid one, have the potential to achieve a higher energy density. In combination with the new battery pack and battery module developments, the endurance of battery could significantly be extended.

Saft R&D is working on developing solid-state battery technology. It is focusing on two main material types: polymers and inorganic compounds, aiming at the synergy of physicochemical properties such as processability, stability, and conductivity.

Although these developments pose threats to lithium-ion battery technology, it doesn’t mean that LIB will be replaced in the near future. For instance, after developing diesel-electric submarines fitted lead-acid batteries, nuclear, fuel cell, and LIB powered submarines have been developed, but submarines fitted with lead-acid battery have kept their important place in the global submarine market.

This is an edited extract from the Lithium-ion Batteries for Underwater Applications – Thematic Research report produced by GlobalData Thematic Research.