Shinichi Nishimura

Air Exposure Effect on LiFePO4

The impact of ambient air exposure on LiFePO 4 /C nanocomposites has been investigated. A pristine sample was prepared without any exposure to ambient air through the whole process of synthesis and characterization and compared to the exposed samples. A small amount of lithium deintercalates from the olivine structure during exposure, a majority of which can be electrochemically reintercalated. This phenomenon changes the initial surface and bulk properties and should be taken into account when diminishing the particle size of LiFePO 4 . Keeping nanocomposites away from oxidative moisture atmosphere could be a solution to minimize these side reactions.

Intermediate Phases in Li x FePO 4

Rietveld analysis for the time of flight powder neutron diffraction profile for LiFePO 4 at room temperature was performed. Refined tensor elements of the unisotropic thermal factor under the elliptic approximation showed the principal axis of the lithium vibration is toward the face shared vacant tetrahedral space and is consistent with the theoretical prediction; lithium ions diffuse along curved one-dementional chain along b-axis. Impact of temperature on the phase diagram of LixFePO 4 with > 200nm particle size was slight under the unmixing line around 200 C. While the reduction in particle size down to