Lithium Battery Technology Energizes the Renewable Storage Market

By Luke Simmons

Advancements in battery technology have revolutionized consumer electronics over the past decade, making them smaller, lighter, and able to last longer on a single charge. Recently, lithium battery technology has made its way into renewable energy storage applications, offering a safer, smarter and more reliable option to those living off the grid or with backup for important loads in a grid outage.

AC Coupled 48V Lithium Battery. Iron Edison Photo courtesy of Iron Edison

The lithium ion battery was first used commercially in the 1990’s, employing a lithium cobalt or lithium manganese chemistry. These first-generation lithium ion batteries have higher energy density than other battery types like nickel-cadmium, which has led to a revolution in mobile technology. The lithium ion battery was originally commercialized by Sony for use in their hand-held consumer camcorders and was later utilized by Motorola in the first StarTac flip phone. This was a major advancement over the large form factor of the nickel-cadmium battery used in the first generation of cell phones. The challenge with lithium cobalt and lithium manganese batteries is they are volatile and prone to thermal runaway which can lead to fire or explosion. A modified lithium chemistry – lithium iron phosphate – has been recently developed, which is both safer and better suited for the home energy market.

In a lithium iron phosphate (LiFePO4) battery, oxygen molecules travel to and from the battery electrodes during the charge and discharge process. In a lithium cobalt or lithium manganese battery, the oxygen molecule travels alone between the electrodes. In the lithium iron phosphate battery, the oxygen molecules are bonded with an element in the electrolyte, so they never travel alone. Fewer loose oxygen molecules of the lithium iron phosphate battery leads to an inherently safer chemistry. The lithium iron phosphate battery is much less likely to ignite if they are mishandled, and a lithium iron phosphate battery will only “steam” under misuse rather than explode. This factor is critical for home safety.

Additionally, an integrated safety system is a requirement for every lithium iron phosphate battery. The “battery management system,” or BMS, keeps constant tabs on cell temperature, voltage and current by using a sensor attached to each cell. If a level is detected that is outside normal operating conditions, a built-in contactor will disconnect the battery from the source circuit. Further, the BMS can log data on an external memory card, helping technicians diagnose any technical issues that may arise. This data can also be used by the end user to track battery performance over time. Next-generation battery management systems will connect to the Internet to allow for remote monitoring of battery performance and state of charge.

With the advent of saver batteries, the market for battery storage for grid applications is booming in the United States. In the second quarter of 2015, the U.S. energy storage market had its best quarter in two and a half years, with 40.7 megawatts of energy storage being deployed, according to a report by Green Tech Media Research and the Energy Storage Association. The debut of the Tesla Powerwall in 2016 is only expected to promote this growth.

Iron Edison Battery Company has also witnessed this growth, seeing record demand for its lithium iron phosphate battery in 2015. The demand has led Iron Edison to start assembling their own lithium iron battery in Colorado, with a roll-out in the last quarter of 2015.

As the market for battery storage continues to emerge in the United States, the lithium iron phosphate battery will be at the forefront. Lighter, smarter, safer and more reliable, Lithium batteries are poised to be the chemistry of choice for renewable energy applications in the 21^st century.

Luke Simmons is a system designer and sales manager at Iron Edison Battery Company. He is NABCEP-certified in PV technical sales and specializes in both grid-tied and off-grid renewable energy systems. He can be reached at (720) 432-6433 or luke@ironedison.com.