Li-Ion Polymer Battery using LiFePO4 as Cathode Material

Many goals, such as low cost, long calendar life, safety and high power capability, have been established for rechargeable lithium batteries in hybrid electric vehicles (HEVs) and other transportation technologies [1,2]. Synthetic graphite and Co-containing cathodes used in commercial cells will need to be replaced with natural graphite and cathode materials based on lower-cost materials, such as those containing iron and manganese. LiFePO4 has been studied as the cathode-active material for Li rechargeable batteries because of low-cost, low toxicity and relatively high theoretical specific capacity of 170mAh/g [3]. We have been studying pouch cells prepared with LiFePO4 cathodes combined with natural graphite anodes with liquid electrolytes [4, 5] However, as Chen and Dahn have already reported [6] small particle sizes need more carbon coating. Recently, Takahashi [7] reported extremely long cycle life or their LiFePO4/graphite cells. The aim of this presentation is to show the performance of LiFePO4/graphite cells using gel electrolyte. In addition, the safety of the anode, cathode and gel will be described. An estimate of cost of the cell using LiFePO4 and gel electrolyte with and without a separator will be compared with cells using LiCoO2.