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.