Hitachi Maxell Ltd announced that it has developed a technology to monitor the movements of lithium (Li) ions in a Li-ion rechargeable battery in real time at the time of charge/discharge.

Also, by using the new technology, the company developed a long-life Li-ion battery whose energy density is 1.6 times higher than that of the company's existing product.

Hitachi Maxell conducted a research for observing the movements of Li ions in collaboration with an equipment maker and developed a technology to directly monitor the reaction between a negative electrode and Li ions that are flowing into the electrode at the time of charge/discharge. As a result, it became possible to quantify the distribution of the reaction of Li ions.

Hitachi Maxell actually observed a negative electrode and found that the possibility of the generation of Li metal dendrites (dendrite crystals), which cause short circuits, increases when the flow of Li ions becomes stagnant.

For positive electrodes, Hitachi Maxell developed a sample making technology that instantly stops the reaction of Li, nickel (Ni), manganese (Mn) and cobalt (Co) oxides and maintains the state in cooperation with Hitachi Ltd. And it enabled to visualize the reaction between Li ions and Li, Ni, Mn and Co oxides on the cross-section of a positive electrode almost in real time with a SPring-8-based imaging technology for X-ray absorption spectrum.

In addition, Hitachi Maxell ran a simulation by using 3D models and developed a structure in which the distribution of reaction in an entire battery is homogenized and the flow of Li ions does not become stagnant.

With those technologies, Hitachi Maxell developed a battery structure that can resolve the stagnation of Li ions. The developed battery has about 1.6 times higher energy density per unit volume than before as well as a longer life because the deterioration of the battery is slower.