User interview – Professor Shohji Tsushima, Osaka University Graduate School of Engineering

The following describes an interview with Professor Shohji Tsushima, who is conducting research on batteries and fuel cells for large-scale electricity storage, which is attracting much attention now. In his research work, Professor Tsushima uses Nano Pulverizer NP-100 and THINKY MIXER.

1. Please outline your current research to us.

The main research subject at present is next-generation batteries such as the flow battery (redox flow battery) and polymer electrolyte fuel cell (PEFC). The flow battery is a rechargeable storage battery that performs charging and discharging via redox reactions of ions such as vanadium. With an increase in the container size of electrolytes, the storage capacity increases proportionally, making the size increase easy. In recent years, therefore, the flow battery is expected to play an active role as a device for large-scale electricity storage and the device is attracting attention in Japan.
In addition to the size increase, it is important to improve the performance of battery devices. What I am working on is the efficient supply of electrolytes to the porous carbon electrode and the use of the phase interface formed by the electrode and the electrolyte to the utmost limit. This will dramatically improve the performance of the flow battery.

2. Tell us what made you install Nano Pulverizer NP-100 and the area of its application

I worked at Tokyo Institute of Technology until June 2014. There, THINKY MIXER AR-250 (successor model: ARE-310) was introduced for the preparation of slurry of electrode materials of polymer electrolyte fuel cells.
Until then, I had performed mixing by hand using a mortar. A friend in the fuel cell industry recommended THINKY MIXER as the de facto standard (practical industry standard). Since then, I have been using THINKY MIXER. As a result, fluctuations due to different persons performing the mixing, which used to be the major source of trouble, have been resolved. This greatly contributed to the improvement of experimental efficiency.
Later, I began research on the flow battery as a member of the PRESTO (Precursory Research for Embryonic Science and Technology) “Phase Interfaces for Highly Efficient Energy Utilization” project of the JST Strategic Basic Research Programs. I introduced Nano Pulverizer NP-100 for pulverizing and disintegrating the carbon used as electrode material.
The conventional porous carbon electrode, mentioned above, has the problem that the improvement of its performance is difficult because it is thick and requires a long distance for ion migration. On the other hand, thinning of the electrode will reduce the area in which ions react. One way to avoid this problem is to make a dense carbon layer on the surface of a thin electrode and increase the surface area. Then, a sufficient reaction area (reaction amount) is achieved, enabling the compatibility of thinness and good performance. NP-100 is used to pulverize carbon into dense particles.
In addition, to deposit carbon on the electrode, an inkjet printer is used after converting carbon and solvent into an inklike material (After evaporation, only carbon remains adhered to the electrode). In this process, it is necessary to keep the diameter of carbon particles sufficiently fine, because the nozzle diameter of the inkjet printer is small. Therefore, the pulverizing function of NP-100 is very useful.
Furthermore, NP-100 meets the needs that even ultratrace amounts can be processed, temperature control (cooling) is possible, and the reproducibility is excellent. It seems to make those who visit the laboratory from outside feel very envious.
Kneading, mixing, and pulverizing are key processes in processing electrode materials. I will continue to make active use of this equipment to contribute to the research and development of future energy devices.

3. It is rare for an expert in mechanics to perform battery research, isn’t it?

Certainly, it is not very common. The research on batteries is usually in the area of materials and chemistry. I think, however, that enlarging equipment and increasing its performance to the limit require those in the role of finishing things up.
When finishing things up, the full performance of the device may not be reached because of just a single problem present somewhere. It is difficult to find where the problem lies without a person who has experience in finishing up things. It is important to have the ability to know what part to focus on after finding the problem, and to identify which of the individually modified parts have the greatest influence on the whole product. I believe that mechanics satisfies these needs.
I am also involved in research on automobiles (research on diesel particulate filter, etc.). In fact, good automobile engines and exhaust-gas treatment equipment cannot be completed without the above-mentioned ability and perspective. I believe that the field of batteries now needs engineers and researchers with the same viewpoint. I suggest to students of mine they do research in such fields.
Both the flow battery and polymer electrolyte fuel cell must be established as the next basic industry in Japan at all costs. Both are devices involving technologies that cannot be easily duplicated by other countries. The processes involved in electrode formation, such as mixing, pulverizing, and coating, for large-scale and large-area products require the finest craftsmanship. In the future, the main competition in the battery industry will be in the pursuit of larger size and higher output. I will work hard so that Japan can continue to enjoy a large lead in battery technology.

Remarks after the interview

It is said that the world market for storage batteries will reach the order of 20 trillion yen in 2020. I hope that Thinky’s products will be more and more useful in Professor Tsushima’s research in the future.

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Brief biography of Professor Shohji Tsushima
Born in Osaka in 1972, he entered the Department of Mechanical Engineering, Faculty of Engineering, Osaka University, in 1991, and later received his doctorate degree for research on spray combustion (Osaka University, 1999). After that, as a researcher of the Postdoctral Fellowship for Research Abroad, Japan Society for the Promotion of Science, he engaged in research on vibration combustion at the Department of Mechanical Engineering, Imperial College London, UK, for one year. From 2000, he worked as a research associate and then as an associate professor at the Department of Mechanical and Control Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology. He was involved in research on, for example, polymer electrolyte fuel cells, flow batteries, lithium ion secondary batteries, diesel exhaust gas purification filters, and carbon dioxide storage. In October 2012, he became a researcher of PRESTO of Japan Science and Technology Agency (additional post, until March 2016). Since 2011, he has been serving as Assistant Subject Editor of International Journal of Hydrogen Energy. In July 2014 (up to the present), he became a professor at the Department of Mechanical Engineering, Graduate School of Engineering, Osaka University.

Affiliated academic societies
The Japan Society of Mechanical Engineers (Chair of Thermal Engineering Division (2012), Secretary of Thermal Engineering Division (2013), etc.)
The Heat Transfer Society of Japan (Chair of Public Relations Committee (2010, 2011), etc.)
American Society of Mechanical Engineers (ASME)
Electrochemical Society (ECS)

Website of Tsushima Laboratory
Website of Tsushima Laboratory > Research Facility Page (Nano Pulverizer and THINKY MIXER are introduced here)