Batteries fuel energy efficient technology

Batteries for EVs get a lot of headlines. But behind the scenes, better chemistries are letting battery makers squeeze more energy into pint-sized packages that are safer and work longer, and last longer than what’s available today. The most promising of these are based on lithium metal, zinc, and metal hydride electrodes.

The problem is, though, that advanced battery chemistries can get confusing. Not all of them are destined to find their way into devices the size of a coin cell. Each chemistry has its niche.

A lot of new chemistries aim to increase battery life. But what’s acceptable as a battery life is largely in the eyes of the beholder. As Sol Jacobs, vice president and general manager of Tadiran Batteries puts it, acceptable battery life is often dictated by application-specific requirements, because product designs must continually adapt to address customer needs as well as keep pace with the competition.

“As a general rule, short-lived batteries can suffice in situations where the product is easily accessible and the costs associated with battery failure are fairly minimal. However, if the device performs a mission- or safety-critical function in a remote location where battery replacement is impossible or not cost effective, then a long-life battery is a must,” he adds. Kohler, the faucet manufacturer, recently asked Tadiran to design a battery system lasting 30 years. The system goes into situations where there is no easy way to replace or recharge batteries, as in public bathrooms.

It’s easy to see the direction of new battery technology from this plot of watt-hours per gram versus watt-hours per liter prepared by Nexergy Corp.
Select figure to enlarge.

Tadiran makes the largest range of lithium thionyl chloride batteries on the market. These primary batteries have been proven to last over 25 years in the field. Their claim to fame is an incredibly high energy density level, the highest of all lithium types, combined with an extremely low discharge rate of less than 1% annually. These batteries are widely used for powering devices in the Smart Grid advanced metering infrastructure (AMI).

The principle primary (non-rechargeable) battery chemistries include alkaline, lithium manganese, lithium sulfur, and lithium thionyl. Alkalines continue to be widely used for powering consumer electronic items and come in a variety of sizes.

Nexergy Corp. prepared this comparison of established and emerging primary and re-chargeable battery technologies in terms of their energy density levels.
Select figure to enlarge.

Major re-chargeable types include sealed lead acid, nickel cadmium, nickel metal hydride, lithium-ion, and lithium polymer to name a few. Nickel metal hydrides are fast replacing sealed lead acid batteries in many applications as a cost-effective transition toward lithium ion.

It looks as though other battery chemistries are ready to compete with rechargeable nickel cadmium, nickel metal hydride and lithium ion batteries. The primary application area for these technologies is in small batteries for consumer electronics, laptop/notebook computers, power tools, and some military applications. One chemistry in particular that looks promising is nickel zinc from PowerGenix Inc. Another is silver zinc from ZPower Inc.

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