Ultrasound technology is used to perform non-destructive "physical examinations" on batteries

Reporter Wu Chunxin, Correspondent Gao XiangCurrently, new energy vehicles, new energy, and information technology are flourishing, with secondary batteries represented by lithium-ion batteries playing a core role.Recently, the reporter learned from Huazhong University of Science and Technology (hereinafter referred to as Huazhong University of Science and Technology) that Huang Yunhui and Professor Shen Yue's team of the university independently developed the ultrasonic scanning imaging equipment for lithium ion batteries, and officially released the latest products at the 15th Shenzhen International Holdings International Battery Technology Exchange Exhibition

Reporter Wu Chunxin, Correspondent Gao Xiang

Currently, new energy vehicles, new energy, and information technology are flourishing, with secondary batteries represented by lithium-ion batteries playing a core role.

Recently, the reporter learned from Huazhong University of Science and Technology (hereinafter referred to as Huazhong University of Science and Technology) that Huang Yunhui and Professor Shen Yue's team of the university independently developed the ultrasonic scanning imaging equipment for lithium ion batteries, and officially released the latest products at the 15th Shenzhen International Holdings International Battery Technology Exchange Exhibition. This product has been independently developed by the Huake University team from its basic principles to software and hardware integration, and has been widely used in the power and energy storage battery industry and academia.

Intuitive and fast monitoring of battery status

As an extremely complex closed system, how to obtain real-time, non-destructive, and in-situ internal information of batteries is the pain point of the development of the battery industry.

During the use of batteries, the electrochemical performance will gradually decline, and the electrode material structure and electrolyte distribution will continue to evolve, accompanied by side reactions such as gas production and lithium evolution, which will affect the battery's lifespan and safety. Huang Yunhui said that there is an urgent need to identify, detect, and evaluate the internal state, especially the health state, of the battery in real-time.

Previously, both academia and industry typically used disassembly methods to obtain internal information of batteries in a destructive manner. Due to the high sensitivity of various components inside batteries to air and changes in state information during disassembly, this method was unable to accurately analyze battery failure mechanisms.

Other non-destructive characterization methods, such as X-ray and neutron diffraction, cannot meet the requirements of real-time rapid detection due to their sensitivity, rapidity, and convenience.

The demand for developing new characterization technologies to meet the real-time detection and health monitoring of batteries in the battery industry is becoming increasingly strong. It is urgent to start from the essence of batteries, accurately obtain internal information of batteries, empower all aspects of the entire life cycle of battery research and development, production, application, and recycling, and achieve optimization and improvement of battery comprehensive performance.

Since 2015, the Huang Yunhui team at Huake University has innovatively proposed the use of ultrasound technology for battery health monitoring to solve battery safety problems. In 2016, they applied for and authorized the core invention patent "A method and device for monitoring the state of charge and health of lithium-ion batteries". In 2017, the team conducted the development of battery ultrasound imaging equipment at the Wuxi Research Institute of Huashi University of Science and Technology.

After years of continuous research and development, the technology and equipment have continuously matured and achieved large-scale application. In 2020, the research results of the ultrasound imaging device developed by the team for monitoring and analyzing battery health status were published in the academic journal "Joule". The results obtained information such as electrolyte infiltration status and trace gas production, which can be used to accurately analyze battery failure mechanisms.

It is reported that the team has developed a series of battery Ultrasonic testing products, using high-frequency ultrasonic transmission method to make the transmitter probe shoot focused sound beam through the battery, and then use the receiver probe to receive. The team evaluates the internal state of the battery through processing and analyzing the received signal, and the imaging accuracy can reach sub millimeter level.

"The battery Ultrasonic testing imaging technology is similar to the hospital's B-ultrasound. We are doing a 'physical examination' for the battery. Through imaging, we can visually and quickly monitor the health status of the battery, find the internal defects of the battery, and ensure the safety of the battery." Huang Yunhui said.

Unique perspective to understand the process of battery failure

Huang Yunhui introduced that the Ultrasonic testing results obtained by the team's R&D technology revealed the evolution law of the internal state of the battery from a unique perspective.

Ultrasound is very effective in identifying gas-liquid and gas-solid interfaces. If there are bubbles inside the battery, ultrasound will undergo significant attenuation. Various battery failure issues such as battery heating and degradation of positive electrode materials are accompanied by the generation of gas products. This technology can identify the process of battery failure through the identification of gas products.

In addition, changes in battery materials can also affect the propagation behavior of ultrasound, and this technology can determine the structural evolution of battery materials based on the differences in ultrasound propagation behavior in different areas of the battery.

With the continuous research and accumulation of battery ultrasound technology, Huang Yunhui's team has found a new perspective to solve the bottleneck problem of batteries.

The team first proposed and observed the phenomenon of battery "retreat infiltration" using ultrasound technology. In the design phase of a battery, the amount of electrolyte used is determined based on the porosity of the battery material. However, during the cycling process, due to issues such as expansion, the original material pores become larger, and the designed amount of electrolyte is insufficient to fill the pores. The electrolyte cannot fully infiltrate the electrode material, which can lead to performance degradation and even more serious failure reactions.

In the past, it was difficult to obtain the true infiltration state of batteries through research, but this technology can observe the evolution of infiltration state in a non-destructive, real-time, and in-situ manner, which is of great significance for studying the failure mechanism of batteries and is also very effective for battery manufacturers. "said Jeff Darn, Chief Scientist of Tesla Battery Project and Professor at Dalhousie University in Canada.

At the same time, the battery Ultrasonic testing technology can also be used to study some battery failure mechanisms such as electrolyte drying, material degradation, etc. during the battery cycle.

At present, the conversion products of this technological achievement have been applied by more than 50 battery and new energy vehicle companies such as BYD and Tesla, as well as some higher education institutions. This technology is gradually becoming a universal device for detecting the internal health status of batteries, and has become a key technology to ensure the safety of power and energy storage batteries, safeguarding the development of new energy vehicles and energy storage industries.

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