Is LiFePO4 stable in water? Toward greener li-ion batteries

The stability of LiFePO4 in water was investigated. From high-resolution transmission electron microscopy observation, electron energy-loss spectroscopy analyses, Mossbauer experiments, and chemical analyses, we showed that a Li3PO4 layer is present at the LiFePO4 grains surface after immersion in water. This layer, which is a few nanometers thick, is accompanied by an increase of the Fe-III percentage in the grains and a continuous dissolution of the layer. If experimental conditions such as immersion time, pH, and LiFePO4 concentration are set to optimal values, the transition to an aqueous route for preparing LiFePO4-based positive electrodes could, in fact, be achieved. (C) 2007 The Electrochemical Society.