Authors:Y. Kato, K. Hasumi, S. Yokoyama, T. Yabe, H. Ikuta, Y. Uchimoto, and M. Wakihara
We have focused on the poly(ethylene glycol) (PEG)-borate ester as a new type plasticizer for solid polymer electrolyte for
lithium ion secondary battery. Adding the PEG-borate ester into the electrolyte shows the increase in the ionic conductivity
of the polymer electrolyte. By measuring the glass-transition temperature of the polymer electrolytes with DSC, it is found
that the increase in ionic conductivity of the polymer electrolyte is due to the increase in ionic mobility. By investigating
the temperature dependence of the ionic conductivity of the polymer electrolytes using William-Landel-Ferry type equation,
we considered that the PEG-borate ester does not have any influence for dissociation of Li-salt.
Authors:M. Tachibana, T. Tojo, H. Kawaji, T. Atake, N. Morita, H. Ikuta, Y. Uchimoto, and M. Wakihara
Heat capacity of spinel LiCr1/6Mn11/6O4-d (d=0, 0.0184)was measured between 5 and 300 K. Both compounds showed no anomaly in the measured temperature range, especially around the
room temperature where a structural phase transition is reported for the parent compound LiMn2O4. The non-stoichiometric compound LiCr1/6Mn11/6O3.9816 has greater heat capacity than that of the stoichiometric LiCr1/6Mn11/6O4. Molecular dynamics study on the vibrational property of LiMn2O4-d revealed that the lattice defects in the non-stoichiometric compound increase the low frequency phonons compared with the
stoichiometric compound. It should be related to the greater heat capacity of the non-stoichiometric compound LiCr1/6Mn11/6O3.9816.