The thermal stability of pristine and electrochemically delithiated LiMPO4 (Carbon coated-LiMnPO4, Carbon coated-LiMn 0.8 Fe0.2PO4, and Carbon coated-LiFePO 4), LiCoO2 and LiNi0.8Co0.15Al 0.05O2 (NCA) composite electrodes with LiPF6 solutions in ethylene carbonate (EC)/dimethyl carbonate (DMC) and EC/propylene carbonate (PC), was investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis, coupled with mass spectrometry. The thermal reactions products were measured by XRD and electron microscopy. The LiFePO 4 and LiMnPO4 cathode materials were found to have comparable thermal stability in their pristine and fully delithiated states. The onset temperatures of the thermal reactions are lower in EC/DMC than in EC/PC solutions but the specific heat evolution of all the thermal reactions are higher with EC-PC solutions. No evidence was found that delithiated LiMnPO 4 or LiMnFePO4 have lower thermal stability than delithiated LiFePO4. The thermal reactivity of the layered LiCoO 2 and LiNi0.8Co0.15Al0.05O 2 cathode materials was found to be comparable to that of the LiMPO4 materials. Oxygen release was detected from the layered compounds upon their heating around 200C.
|Journal||Journal of the Electrochemical Society|
|State||Published - 2011|