GS Yuasa, the provider of the LEV50 Li-ion cell (earlier post) used in the battery pack for the i-MiEV, is developing a 25 Ah lithium iron phosphate (LFP) prototype, said Dr. Masanori Kitamura from GS Yuasa’s Corporate Strategic Planning group in a presentation at the Advanced Automotive Battery Conference 2009 (AABC).
Dr. Kitamura is also a director of Lithium Energy Japan, GS Yuasa’s joint venture with Mitsubishi.
The LEV50 cell going into the i MiEV pack is a 50 Ah, 3.7V cell using a mixed LMO/NMC cathode material with a hard carbon anode. The combination offers a specific energy of 109 Wh kg-1, and energy density of 218 Wh L-1.
In his presentation at AABC in 2008, Kitamura noted that GS Yuasa was beginning work on a 50 Ah LFP cell; the 25 Ah prototype is an evolution of the work focused on a practical application. The cathode material used is a carbon-loaded LiFePO4 combined with a graphite anode. The carbon loading improves the high-rate discharge capacities by about 25%.
The cell is showing densities greater than 182 Wh L-1 and 81.3 Wh kg-1, with a flat voltage profile.