[System Introduction]

When a material needs to be industrialized, we must grasp most of its properties as widely as possible and with high precision, so as not to affect the direction of industrialization at a later stage due to wrong data and cause unnecessary losses.

4990EDMS-120K is the world's first high-frequency impedance testing system for all-solid-state batteries, originally developed by Toyo Teknika Corporation (Chinese Patent No.: 201780096021X). With high frequency impedance testing up to 100MHz, this system can separate particle and particle boundary impedance of solid state electrolyte. Combined with the automatic temperature control function of -180℃ ~ +200℃, this system can provide the most accurate internal resistance measurement environment for solid-state electrolyte activation energy calculation to date.

Since its launch, the test system has sold nearly 100 sets in Japan and has been approved by many top solid state electrolyte material research institutes in Japan.

[Technical Explanation]

The current lithium-ion secondary batteries (now LIBs) use organic electrolytes and have problems such as "heat resistance" and "fear of leakage". On the other hand, an all-solid-state LIB requires an upper frequency of at least 100 MHz for the following reasons.

The performance of an all-solid-state LIB is strongly influenced by the transfer resistance value of lithium ions (Li+) in the solid-state electrolyte. For example, a solid electrolyte is formed by pressing a ceramic powder or by sintering it after pressing to create a solid electrolyte. Therefore, there are two paths of Li+ movement in a solid electrolyte: in the powder (intracrystalline) and at the powder-powder interface (grain boundaries), and the resistance to Li+ movement is the intracrystalline resistance component (Rbulk) and the grain boundaries. There are two components, the resistance component (Rg.b.) (see Figure 1). Capacitance is also formed at the grain boundaries (grain boundary capacitance: Cg.b.). In the development of solid electrolytes, the goal is to reduce the resistance to movement of Li+, but to achieve this, the resistance to movement of the solid electrolyte is divided into Rbulk and Rg.b. It is important to determine if it hinders). Cg.b. is too small to be detected in conventional measurements up to 1 MHz, and it is not possible to separate the two resistance components. Considering the size of Cg.b., the upper frequency needs to be at least 100 MHz and measurements need to be made over a wide frequency range from 10 mHz to 100 MHz.

Figure 1 Movement path of Li ions in solid electrolyte and simulation circuit

[System Specifications]

EDMS control software manufactured by Toyo Corporation

It controls CV measurements and impedance measurements, and supports complex test patterns.

Arrhenius evaluation of particles and particle boundaries by variable temperature and high frequency impedance measurements

• For impedance testing of oxide or sulfide samples after powder pressing and sintering, the impedance of the sample can be ideally divided into three components: particle individual impedance, particle boundary (interparticle) impedance, and electrode interface impedance. In the case of activation energy characterization, Arrhenius curves can be obtained by measuring the impedance at each temperature point, but the impedance of highly mobile particles is very small, and it is not possible to obtain independent impedance spectra of particles and particle boundaries at frequencies of 1 MHz.
• This test system enables impedance testing up to 100MHz over a wide temperature range of 90K (-183°C) to 873K (600°C). This system enables the separation of impedance values of particles and particle boundaries of solid electrolytes and other materials and independent characterization.