SPring-8, the large synchrotron radiation facility

Hitachi Maxell, Ltd. (Maxell; president, Yoshihiro Senzai) has established a technology for the real-time visualization of the movement of lithium ions during charging and discharging and has incorporated it into the development of batteries for the first time in the world.^*1 The newly established technology enables the development of a highly reliable long-lifetime lightweight lithium-ion battery that has 40% reduced weight per unit energy density,^*2 1.6-fold increased energy density per unit volume,^*2 and a lifetime of at least 10 years^*3 using materials with a high energy density.

Lithium-ion batteries used in home energy management systems (HEMSs) are required to have high reliability and a lifetime of at least 10 years. Generally, materials with a well-known low energy density are used for the cathode and anode to ensure high reliability.

The visualization technology established by Maxell has made it possible to quantify the variation in the reaction of lithium ions, greatly promoting the development of electrode structures that can improve the reliability and lifetime of batteries.

In cooperation with equipment manufacturers, Maxell carried out a study to evaluate the movement of lithium ions around an anode and applied a technology for the real-time observation of a battery cross section to the development of batteries for the first time in the world. By directly observing the reaction between the lithium ions flowing into the electrodes and the anode, it was found that the risk of generating lithium metal dendrites increases when the flow of lithium ions stagnates.

In cooperation with Hitachi, Ltd., Maxell developed an original sample preparation technology for the cathode that can instantaneously stop the reaction of lithium nickel manganese cobalt oxides and maintain the state of the cathode. Moreover, the reaction between the lithium ions and the lithium nickel manganese cobalt oxides at the cross section of the cathode was visualized in almost real time using the Industrial Consortium Beamline (BL16B2) at SPring-8 and X-ray absorption spectroscopy imaging, confirming the distribution of the reaction.

In addition, problems related to batteries were efficiently determined by simulation involving cutting-edge three-dimensional models to homogenize the distribution of the reaction in the entire battery and prevent the stagnation of the lithium-ion flow.

As discussed above, Maxell established an efficient coherent technology for developing batteries involving three advanced techniques for (1) determination of the problems to be solved, (2) improvement of the cathode/anode structure, and (3) visualization and demonstration of the electrode reaction. A battery structure that can avoid the stagnation of the lithium-ion flow was thus developed. It has become possible to develop highly reliable, long-lifetime, and lightweight batteries that have 40% reduced weight per unit energy density, 1.6-fold increased energy density per unit volume, and a lifetime of at least 10 years using materials with a high energy density. These batteries can be used for HEMSs and other applications.