Electrochemical nanotechnology has been utilized in the field of information storage devices, chip interconnects, microelectronics packaging, energy devices, and sensor fabrication. It has yielded a variety of materials at the nanometer scale. These nanoscale materials have realized the miniaturization of electric devices, and their attractive characteristics, which are remarkably different from those of bulk materials, still fascinate researchers. We have established our original research philosophy of “new design for the interface between the solution and electrode at the atomic scale,” which led to the first trial in the development of a high-performance magnetic recording head material for electroless CoFe deposition. Today, this philosophy is an essential common idea that is applicable not only to electrochemical wet technologies. Recently, biotechnology has helped us get closer to a biological entity and has played an essential role in healthcare fields such as biomedicine and bioanalysis. We are currently attempting to realize the magnetic sensing of biomaterials and to develop a drug delivery system utilizing magnetic nanoparticles as markers or carriers. For this purpose, iron-oxide magnetic nanoparticles were prepared with various diameters ranging from 4 nm to several tens of micrometers; γ-Fe2O3 magnetic nanoparticles have a considerably high crystallinity and narrow size distribution. Furthermore, we are attempting to control surface conditions for the immobilization of biomaterials by introducing organic molecules with amino groups on the surface of the nanoparticles for applications in the field of medicine.
As a research strategy across Darwinian Sea to deliver these devices to the industry, we introduced an approach related to battery evaluation as an example. Electrochemical impedance spectroscopy (EIS) has been utilized to characterize each elemental process of electrochemical devices because it enables us to analyze the dynamics of each elemental process sensitively and separately without destruction of the cell. The equivalent circuit to express each elemental process in a commercial lithium-ion battery (LIB) by EIS has been carefully investigated. Furthermore, an equivalent circuit has been designed for the analysis of LIBs with the contributions from a variety of diffusion parameters resulting from the various particle sizes of the cathode and the solid-electrolyte interphase formed on anode particles, as well as electrochemical reactions and inductive components. However, it is not easy to measure the impedance of large-scale LIBs with conventional EIS using frequency response analyzer (FRA) – potentiostat systems because of its low internal resistance. Moreover, an FRA – potentiostat system for conventional EIS measurement cannot be mounted on a vehicle. Thus, an impedance measurement technique that does not use FRA – potentiostat systems is needed. In our study, the application of a square-wave potential as input signals of EIS was investigated in a simple electrochemical reaction to verify a new technique called “square-potential/current electrochemical impedance spectroscopy (SP-EIS, SC-EIS),” which is an EIS method that does not use FRA systems. We applied SC-EIS to evaluate the state of a commercial stationary storage battery system that uses LIB technology. With the new method, we were able to conduct EIS measurements for a large-scale LIB system. Moreover, under operando conditions, data were acquired smoothly.
In order to continue such integrated research, it is necessary to procure management resources such as funds and human resources properly, and we would like to discuss the activities of a wide range of fields related to our research.