The Revolution in Rechargeable Batteries: Lithium Iron Vs Lithium Ion
Newer rechargeable lithium batteries use lithium iron phosphate, or LiFePO4. From both a health perspective and an environmental viewpoint, this non-toxic chemical is a significant improvement over the older Li-ion (lithium ion) rechargeable battery made of lithium cobalt dioxide LiCoO2.
Health and Environment Advantages of Lithium Iron Batteries
The materials used in batteries should be non-toxic, non-irritating and safe to manage at either end of the battery’s life. Material safety is a concern for both manufacturers and waste disposal sites.
Manufacturing with lithium iron phosphate is safer than using lithium cobalt. One material handling sheet states that lithium cobalt is a hazard that may harm or irritate eyes, skin or the respiratory tract and may cause harm if swallowed. A material handling sheet for lithium iron phosphate considers it a fairly safe powder unless it is burning.
Like the talcum powder used on a baby’s bottom, neither substance should be deliberately ingested or rubbed into one’s eyes. However, contact with lithium cobalt requires professional medical attention; lithium iron does not.
Disposing of any lithium products should be a matter of recycling. One reason is simply that lithium is a somewhat limited resource. However, Li-ion’s lithium cobalt is an environmental risk if it leaches into soil or water.
Uses for Lithium Batteries
Lithium batteries are top choices for high-performance rechargeable battery packs. They are used in cameras, electric vehicles and laptop computers. Electric bicycles and scooters form a growing consumer market, although some of these still use the lead-acid batteries familiar in gasoline-powered automobiles. Hybrid automobiles use lithium battery packs.
Lithium batteries store more power for the same weight than most other commercially available batteries. They store nearly the same charge over their useful lifetime, where some earlier batteries lost capacity more quickly.
Other Advantages of Lithium Iron Over Lithium Ion Batteries
Under the stress of rapid charging or heavy use, a lithium ion battery may heat very quickly, causing a fire. Lithium iron batteries stay much cooler under the same stress.
Some testing has shown that lithium iron phosphate batteries can last about 2,000 charge/discharge cycles, compared to perhaps 1,500 for lithium ion batteries. These tests go to the point where the batteries hold noticeably less charge, rather than testing to a point of utter failure. As well, a lithium iron battery may have a longer “shelf life” than a Li-ion battery.
Iron and phosphate are less expensive than cobalt, so the cost of raw materials should be less when making the chemical compound LiFePO4 than LiCoO2. Presumably, it would be less expensive to handle non-toxic lithium iron phosphate than lithium cobalt dioxide. It remains to be seen whether these advantages result in lower manufacturing costs overall.
Notes for Users of Rechargeable Lithium Batteries
Lithium ion batteries may have a slight advantage in terms of total power, at least when comparing newly manufactured batteries. Each type of lithium battery would benefit from a breakthrough in reducing the time it takes to fully charge.
Consumers should check what types of battery are available when purchasing their next laptop computers, digital cameras or electric vehicles.
Disclaimer: The information contained in this article is for educational purposes only and should not be used to guide purchases without the opinion of a technical professional.
Allan Chen, Berkeley Lab, “Batteries of the Future II“, published Feb. 2007, referenced Oct. 16, 2010.
Rho, Nazar, Perry and Ryan, Journal of The Electrochemical Society, “Surface Chemistry of LiFePO4 Studied by Mössbauer and X-Ray Photoelectron Spectroscopy and Its Effect on Electrochemical Properties”, published Feb. 9 2007, referenced Oct. 16, 2010.
Michel Gautier, Université de Montréal, “Phostech’s advanced C-LiFePO4 cathode for EV-PHEV-HEV“, published Sept. 2009, PDF referenced Oct. 16, 2010.
Guerfi, Charest, Dontigny, Peticlerc and Zaghib, Hydro-Québec, “Olivines for HEV and PHEV Applications“, published Nov. 200, PDF referenced Oct. 16, 2010.
Sigma-Aldrich, “Material Data Handling Sheet (Lithium cobalt(III) oxide)“, revised Feb. 28, 2010, referenced Oct. 16, 2010.
MTI Corp., “Material Data Handling Sheet (LiFePO4 Powder for Li-ion battery Cathode)“, revised June, 2010, PDF referenced Oct. 16, 2010.
MetaEfficient.com for two images referenced Oct. 16, 2010.
MIT.edu newsoffice for two images by Donna Coveney, referenced Oct. 17, 2010.