The bipolar LiAl/FeS2 battery is being developed to achieve the high performance and long cycle life needed for electric vehicle application. The molten-salt (400 deg C to 440 deg C operation) electrolyte composition for this battery has evolved to support these objectives. An earlier change to LiCl-LiBr-KBr electrolyte is responsible for significantly increased cycle life (up to 1000 cycles). Recent electrolyte modification has significantly improved cell performance; approximately 50 % increased power, with increased high rate capacity utilization. Results are based on power-demanding EV driving profile test at 600 W/kg. The effects of adding small amounts (1 mol-% to 5 mol-%) of LiF and LiI to LiCl-LiBr-KBr electrolyte are discussed. By cyclic voltammetry, the modified electrolytes exhibit improved FeS2 electrochemistry. Electrolyte conductivity is little changed, but high current density (200 mA/cm 2) performance improved by approximately 50 %. A specific feature of the LiI addition is an enhanced cell overcharge tolerance rate from 2.5 mA/cm2 to 5 mA/cm2. The rate of overcharge tolerance is related to electrolyte properties and negative electrode lithium activity. As a result, the charge balancing of a bipolar battery configuration with molten-salt electrolyte is improved to accept greater cell-to-cell deviations.
Modification of LiCl-LiBr-KBr electrolyte for LiAl/FeS2 batteries
Modifikation des Elektrolyten LiCl-LiBr-KBr für LiAl/FeS2 Batterien
1996
13 Seiten, 9 Bilder, 13 Quellen
Conference paper
English
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