The development of low cost LiFePO4-based high power lithium-ion batteries

Pouch type LiFePO4-natural graphite lithium-ion cells were cycled at constant current with periodic pulse-power testing in several different configurations. Components were analyzed after cycling with electrochemical, Raman and TEM techniques to determine capacity fade mechanisms. The cells with carbon-coated current collectors in the cathode and LiBOB-salt electrolyte showed the best performance stability. In many cases, iron species were detected on the anodes removed from cells with both TEM and Raman spectroscopy. The LiFePO4 electrodes showed unchanged capacity suggesting that the iron is migrating in small quantities and is acting as a catalyst to destabilize the anode SEI in these cells.