High-Temperature Storage Performance of Li-Ion Batteries Using a Mixture of Li-Mn Spinel and Li-Ni-Co-Mn Oxide as a Positive Electrode Material

摘要

To improve the storage performance of Li-Mn spinel at high temperatures, we investigated a mixture of Li-Mn spinel (Li_(1.1)Mn_(1.9)O_4) and Li-Ni-Co-Mn oxide (LiNi_(0.4)Co_(0.3)Mn_(0.3)O_2) as a positive electrode material. We found that a battery using such mixture as a positive electrode material showed better storage characteristics at 45 deg C for 30 days than batteries using both a single material Li-Mn spinel and a single material Li-Ni-Co-Mn oxide. This improved storage performance resulted from the suppression of capacity loss of LiMn-spinel in the mixture. We compared the differences in Li-Mn spinel to clarify the reasons for improved storage performance in the mixture and found two changes during charging in the potential and lattice constant of Mn spinel in the mixture that were different from those of single material Li-Mn spinel. In single material, changes in potential d lattice constants of Li-Mn spinel showed two-step change when charged, while Li-Mn spinel in a mixture showed continuous change.