Discuss the new reformation of lithium battery cover plate

Batteries are the driving force behind the electric car industry. In the past few decades, rechargeable lithium ion batteries have made great progress as manufacturers have been striving for greater energy density, longer service life and better safety performance.

In March 2017, the ministry of industry and information technology of China and three other national ministries and commissions jointly released the action plan for promoting the development of the automotive power battery industry. The action plan lays out three development stages for the development of China's automotive power batteries. First, continuously improve the performance, quality and safety of existing products, further reduce costs, and guarantee the supply of high-quality power batteries by 2018. Second, vigorously promote the research and development and industrialization of new lithium-ion power batteries, and achieve large-scale application by 2020; Third, we will strengthen basic research on new systems of power batteries and achieve technological change, development and testing by 2025. All these efforts are aimed at reducing costs, improving the performance of chinese-made power batteries and giving China's electric car industry a greater competitive edge in the global market.

Challenges and opportunities

But the price of lithium-ion batteries, which account for a full third of the total cost of electric vehicles, is still high, and owners and manufacturers will not be happy to spend much money replacing them. Crucial to the Chinese market is making sure consumers don't hesitate to buy electric cars because of the high cost of battery replacements. Overall sales growth will be needed to reach the target when the general public can afford to buy and maintain electric cars.

Therefore, high efficiency and strong performance is of great importance to power batteries, especially the pure electric range of vehicles and the extension of battery life. If these difficulties can be overcome, China's lithium battery industry will remain competitive in the global market. Finding the right solution to improve battery performance is one of the most discussed topics in China's electric vehicle industry. At present, the discussion in this field mainly focuses on battery raw materials, positive and negative electrodes, electrolytes, membranes, battery PACK system and battery management system (BMS) and other technologies. However, the stability of a single battery housing and its potential structural weaknesses are often overlooked as factors affecting battery performance and service life.

Find the weak link in the battery

It is important to note that the battery has some potential weaknesses. The first is a seam layer between the battery "tank" housing the electrolyte and battery components and the battery cover plate. The air tightness of the battery was tested in a vacuum chamber. If the battery already has electrolytes, 3-5% helium will be added for further testing. In a vacuum chamber, leaks as small as 10-6 or 10-7mbar·l/s can be detected by helium testing.

Other weak links include electrodes, filler holes and safety holes. In the field of electric vehicle applications, polymer materials are usually used for sealing, but the organic components of the polymer are at risk of degradation and aging over time. In addition to the problem of electrolyte leakage (the electrolyte can be volatilized out through the polymer seal), once water vapor enters the battery, it may react with lithium salts to generate acids, such as hydrofluoric acid, which will adversely affect the chemical balance and reduce the battery performance. At the same time, it is highly corrosive to the battery as a whole.

The use of batteries in electric vehicles faces many challenges due to the vibration and heat of the vehicles, as well as environmental problems such as bad weather and dust on the streets. Action plan for promote the development of the auto power battery industry in points out that the battery must ensure that can in - 30 ℃ to 55 ℃ 1 safe operation temperature range. In the 2016 energy conservation and new energy vehicle technology roadmap issued by the Chinese society of automotive engineering, the standard number of battery charging cycles should be greater than or equal to 4,000 times within 10 years. Ensuring that the battery is impermeable and completely isolated from the outside world to optimize performance is therefore a critical task for ev manufacturers.

Short launches glass - aluminum seal (GTAS)

Usually the battery cover plate is fixed on the tank body by laser welding technology, which can form an air-tight connection. The polymer seal is the only potential remaining leak point. If advanced new glass - aluminum sealing (GTAS) materials are used instead of polymer as sealing materials, the problem of air tightness can be improved. The use of glass and aluminum in the sealing field is an innovative design. By constantly adjusting the glass composition with aluminum, the thermal expansion coefficient of the two materials matches each other, and finally achieves the impenetrable and lasting sealing effect.

This process is called compression seal. When two materials are heated, metal expands faster than glass. Then, once the cooling process starts, the metal begins to contract at a faster rate than the glass, applying compression from the outside and sealing the battery's electrodes inside. The pressure generated by this process ensures a strong mechanical bond between the glass and the aluminum alloy. This is of great significance for electric vehicles and other applications that require extremely high stability between operating components and batteries.

Glass - aluminum seal - leap forward

Glass - aluminum seal (GTAS) is the first electronic packaging department of short group in Germany. Its glass-metal seal technology (GTMS) has been widely used to seal electronic components such as automotive sensors, capacitors and airbag initiators. After a lot of research and development work on GTMS, short's technicians developed glass - aluminum seal GTAS technology for lithium battery aluminum package.

Replacing the polymer with a high-performance glass-to-aluminum sealing technology can effectively prevent the polymer from aging and corrosion over time. This, in turn, protects the stability of the chemicals inside the battery, ensuring longer life and better battery performance. Domestic sales of electric cars are expected to exceed 1m this year, and Chinese battery makers can use the technology to better serve the growing market for electric cars.

Short is a leading international technology group in the field of specialty glass and glass ceramics. We have decades of experience in the automotive industry, and our products can provide long-term and reliable protection for sophisticated automotive electronics and lithium batteries.

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