Industrial CT applications play a vital role in battery failure analysis. On January 7, 2013, a fire broke out on Japan Airlines Flight JA829J parked at Boston International Airport in the United States. The flight was operated by a Boeing 787 passenger plane. The fire source is the auxiliary power unit on the Boeing 787 aircraft. After an intermediate investigation report published by the National Transportation Safety Board (NTSB), the aircraft’s auxiliary power unit suffered severe burns. It can be judged that the accident was caused by the overheating of the battery pack which caused a fire.
On April 26, 2015, at a power station in Shenzhen, the battery pack in the bus caught fire and the bus was burned into a skeleton. According to reports, the direct cause of the accident was: after the vehicle's power battery was fully charged, the power battery was overcharged for 72 minutes with an overcharge of 58kWh, causing thermal runaway of the power battery and electrolyte leakage in multiple battery boxes, causing a short circuit and causing a fire. ("Report | Shenzhen 4.26 Electric Bus Fire Investigation Results Announced: Overcharge Caused Fire")
In the early morning of July 22, 2015, a fire broke out in a bus parking lot in Xiamen. A total of 11 buses were burned at the scene, many of which were almost burnt to their skeletons. According to reports, the cause of the fire was the electrical failure of the battery pack at the rear of the bus, which caused spontaneous combustion. Of the 11 buses that were caught in the fire, 6 were hybrid buses.
On January 9, 2016, in a smart phone retail store in Switzerland, a mobile phone battery injured 1 clerk and 7 others. More than 50 people, including employees and customers, were evacuated in an emergency.
[Netease Intelligence News, March 25th] On Friday morning, US local time, a blue Tesla Model X was driving south on the US 101 highway and hit the middle isolation fence, causing the car to catch fire. Subsequently, this Tesla was collided by a Mazda coming from behind in the same lane, and then hit by an Audi. A total of 3 cars were involved in this accident. The California Highway Patrol immediately shut down Highway 101. Four lanes of the southbound highway.
New energy batteries are mainly divided into two categories: smart electronic product batteries and power battery packs. The failure mechanism modes of the positive and negative electrodes of lithium-ion batteries mainly focus on the decomposition of SEI film, the generation of lithium dendrites or copper dendrites, and active material particles. The pulverization and shedding of the material, the thermal decomposition of the material to produce gas, etc. Among them, the generation of lithium dendrites or copper dendrites, and the decomposition of materials to produce gas can easily cause thermal runaway of the battery cell and cause the battery to burn. In the final analysis, the failure research of lithium-ion batteries is to optimize the materials and structure of the battery through the discovered failure modes and mechanisms to improve the environmental adaptability, reliability and safety of the battery.
1. CT detection of batteries for smart electronic products
On September 8, 2016, the leader of the smart phone created a global uproar. Inquiring the essential cause became the primary task. At this time, the non-destructive testing technology of industrial CT played an important role and became the failure case analysis. Indispensable means. For this batch of batteries, the batteries were disassembled and inspected. There were internal short-circuits in the batteries of 6 damaged devices. CT scans were performed on 30 batteries. Short-circuits, deformation of the upper right corner, and problems in the assembly and manufacturing processes were also found to cause the batteries. Deformation and battery design issues have led to thinning of the separator.
For the second batch of batteries, the results of the analysis at this stage found that there were internal short circuits in different positions of the batteries in the five devices, there was a lack of insulating tape on the cathodes of the expanded batteries, and burrs were found on the convex edges. The second stage charge and discharge temperature test was normal, and the third stage CT scan did not find any defects. Production quality problems: The thinner isolation film is the main reason. The manufacturing defects of the two-pole tabs cause burnout. The joint damage of the two-pole tabs is an internal defect, and the internal pressure of the battery is too high. That is, the defects in the joint between the anode plate and the cathode plate cause problems, because the joint process problems cause sharp bumps and cause short circuits.
Similar to mobile phone batteries, the failure analysis and high-precision imaging of industrial CT are also used to scan other electronic wearable products, such as earphones, watches, tablet computers, etc.;
2.power battery CT test
The global focus is on the development of new energy industries such as electric vehicles and energy storage batteries. Lithium batteries have received greater attention as a recognized ideal energy storage component. my country has also invested huge funds and policy support in the field of power batteries, and there have been eye-catching backbone companies in the global battery industry such as BYD, BAK, Lishen, and AVIC Lithium. Cathode materials, anode materials, battery separators, and electrolytes are the four important raw materials for lithium batteries. Due to high investment risks and high technical thresholds, lithium battery separators have not been able to achieve large-scale domestic production, which has become a bottleneck restricting the development of my country's lithium battery industry. , Especially in the field of power lithium-ion batteries that require higher safety and consistency, it is an insurmountable obstacle for my country from a large lithium battery production country to a lithium battery production country.
At present, the global Li-ion Cell production capacity is rapidly expanding, and the growth rate of the production capacity of lithium battery separators as the main material is lagging. Many battery manufacturers have expressed the shortage of separators to varying degrees. The development of the battery industry is an urgent requirement. Therefore, the emergence of more national enterprises with the same Xingyuan material as soon as possible in the country is an important measure to improve the industrial chain of my country's lithium battery industry and enhance the competitiveness and sustainable development capabilities of my country's lithium battery manufacturers. It is also related to my country's new energy automobile industry. The key to rapid development.
Contact Person: Mr. James Lee