Succeeded in establishing an ion-conductive polymer matrix system and developing a highly safe solid electrolyte lithium-ion batteryPIOTREK Co.,Ltd


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Various solid electrolyte lithium-ion and high voltage lithium-ion batteries are developed using an ion-conductive polymer matrix system.

Points to remember

  • Establish mass production technology of “Ion-conductive polymer” which is the basis for the development of solid electrolyte lithium ion battery
  • Develop ion-conductive polymer matrix technology using ion-conductive polymer
  • Complete the prototype of solid electrolyte lithium ion and high voltage lithium-ion batteries

Since its founding in 1996, Piotrek Co., Ltd., has set a goal of developing a new lithium-ion battery (LIB). The commonly used organic electrolyte system LIB contains petrochemicals and has the risk of ignition. The electrolyte often causes laptops, smartphones and aircraft parts to catch fire. Changing the organic electrolyte system LIB having associated risks by developing a highly safe, thin, soft and flexible LIB is also socially aspirational.

Meanwhile, the company established a mass production technology for “Ion-conductive polymer” based on which LIB has been developed. In 2016, they obtained patents in Japan and other major countries in the world. If the flammable organic electrolyte can be replaced with the non-flammable “Ion-conductive polymer” electrolyte, fully solidified lithium-ion battery with high safety can be ensured.
For example, the “Ion-conductive polymer” is synthesized by polymerization of an ionic liquid framework to a fluorine-based polymer, giving ionic conductivity to the fluorine resin polymer which is originally an insulator. In other words, the company has established the technology to control the synthesis of the basic framework material of multifunctional conductive polymers. The “Ion-conductive polymer” can be developed and applied to a wide range of needs, and by controlling characteristics such as conductivity and binding strength, the company is developing many new materials such as ion-conductive binders and interface control materials for solid electrolytes.

The company succeeded in the systemization of the solid electrolyte (SE) and ion-conductive polymer matrix (ICPm) technology and completed a prototype of the highly safe “Solid electrolyte LIB”, which has the same efficiency as the organic electrolyte system LIB.

Particle interface resistance and interface resistance of the electrode and the solid electrolyte was completely controlled

Previously, the following were the two main problems in synthesizing “Solid electrolyte LIB”.
(1) It was a challenge to control the resistance generated at the particle interface of the solid electrolyte. The company developed an interfacial coating material for the particle interface and succeeded in reducing the interface resistance to almost zero with a thin film coating.
(2) Interface resistance generated in the solid electrolyte and electrode was also a problem. The company replaced the conventional polyvinylidene fluoride (PVdF) electrode with an ion-conductive binder to form a homogeneous conductive network structure by close packing and succeeded in developing an ideal electrode that can conduct Li positive ions with stability (Refer to the above figure).

Similar developments are being promoted in Europe, but they were able to achieve only temperature dependence up to now. Since the temperature-dependency of “Solid electrolyte LIB” developed by the company is very low, it can be used between temperatures -30°C to 60°C. The “Solid electrolyte LIB” established by the company is a unique technology with world-class superiority.

The company is also developing a high voltage system LIB.
Though the electrolyte system is a liquid and a not solid, non-flammable and non-volatile ionic electrolyte is used instead of the conventional organic electrolyte system which has the risk of catching fire. The separator used in the liquid system LIB is subject to a surface treatment with an ion-conductive polymer to form a layer of several microns in a three-dimensional structure significantly improving the impregnation of ionic liquids and various other electrolytes. The surface-treatment enables elimination of static electricity which had been an issue.
As a result, LIB with high voltage can be manufactured, and the long-term capacity of the battery can be increased. In the case of storage batteries such as those used in automobiles where the required capacity is known, the number of battery cells installed can be reduced by using a high voltage battery contributing to weight reduction and saving space in automobiles.

The company's booth was very successful at the 10th Int'l Rechargeable Battery Expo held at Tokyo Big Sight.

The ion-conductive polymer matrix technology was presented at the 10th Int'l Rechargeable Battery Expo held on February 27, 2019. The company's booth was visited by nearly 600 visitors, which indicates a high level of interest in technology.
In the future, the company will start mass production of ion-conductive polymers. A groundbreaking ceremony was held on March 22, 2019, for the construction of a new factory in Shiga Prefecture. The new plant is expected to start full-scale operations in 2020.
At the same time, they will raise business investment for the company. The company will offer patent licensing and engineering assistance, know-how, to construct factories for mass production in various countries around the world for various business applications.

The world market of LIB was approximately 4 trillion yen in 2018 and is expected to exceed 7 trillion yen in 2022 (2019, Fuji Keizai). The company estimates that “Mass production of solid electrolyte LIB will start around 2022, gradually replacing the existing organic electrolyte system LIB, and become a mainstream product in 2025. A few years later, the share of high-voltage LIB will also increase”.
With such a big market, the unique ion-conductive polymer matrix technology of the company is expected to contribute to the development of LIB significantly. In addition to the development of LIB, the technology is being expanded to various applications such as resin modification and electrochemistry. The company will also pay attention to future trends.

Interview Date: March 28, 2019


company information

We have developed our own ionic liquid, and polymer obtained by graft polymerization, and mainly achieved the commercialization of our ion conductive polymer, and commercialized our multi-functional conductive binder, electrode for LIB, obtained by the use of the binder, ion conductive functional material, etc. In addition, we also work on various types of contracted tests from material evaluation to safety tests, and technology consulting work.

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