Development of long life lithium ion battery for power storage

With the aim of developing lithium ion batteries with a long life and high efficiency for power storage, we experimentally evaluated combinations of cathode and anode active materials, in which batteries are able to obtain over 4000 cycles or 10 years of life. An acceleration method was evaluated using coin cells. We found that changing the current density was effective for evaluating battery life, since the logarithm of the cycle life showed a linear relationship to current density. Based on the current density increasing method, various combinations of cathode and anode active materials were tested. The cell system of LiCoO₂/Li_4/3Ti_5/3O₄ clearly showed a long life of about 4000 cycles. The energy density of the cell using the Li_4/3Ti_5/3O₄ anode is obviously smaller than that using a graphite anode, the cell with Li_4/3Ti_5/3O₄ anode was thought to have some merit especially in the large-scale-layer-built type battery by the applicability of the Al anode collector and a light weight battery case.