The Evolution of Electric Vehicle Battery Pack Enclosures

 

With the rapid growth of the global new energy vehicle market, battery technology, as its core component, has received widespread attention. In particular, the material selection and production process of battery shells are of great significance in improving electric vehicles' safety, efficiency, and cost-effectiveness. This article will detail several advanced battery aluminum shell solutions, aiming to provide customers with comprehensive technical support and application suggestions.

 

 

Arguably one of the most important components in an electric vehicle (EV) is the one that keeps the battery dry, secure, and safe in the event of a crash or fire. There are many terms used to describe this component: housing, casing, tray, box, and enclosure; the materials currently used for battery pack housings include steel, aluminum, and plastic composites.

 

Not surprisingly, complete EV battery packs are quite heavy, typically accounting for around 40% of the total vehicle weight; when you consider the components of a battery pack (cells and modules, thermal management, battery management system BMS, separators, etc.), it's easy to see why they are also very expensive, totaling up to 50% of the vehicle's value.

 

This is why batteries need to be handled with care both while in use and after use in an EV; when a power battery in an EV reaches the end of its useful life, it still has a lot to offer the world, whether through recycling or secondary use, so the power battery needs to be easily disassembled for recycling.

 

 

 

Removable

 

Key to current battery enclosure design strategies are removability, fire and thermal runaway protection, crash performance, and recyclability. However, the EV battery market is evolving rapidly, with frequent changes in battery chemistry, battery packaging formats (soft pack, cylindrical, prismatic), and battery technology, and the arrival of solid-state battery technology is getting closer. All of this has an impact on EV battery enclosures.

 

As we will see, the role of the battery enclosure in vehicle architecture is evolving, increasing structural requirements, which in turn raises questions about material availability, joining techniques, and suitability requirements.

 

About 80% of electric vehicles currently use aluminum battery enclosures, with the rest dominated by steel, but new thermoplastic solutions offer a lightweight and innovative alternative to metal solutions.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Battery Pack Shell Material Selection

 

The age-old debate between steel and aluminum continues in the battery enclosure space, with each supplier claiming to be better suited than the other. Steel manufacturers tout their advantages in high strength, formability, and repairability, as well as cost-effectiveness, and that they require less carbon intensity than other materials during production.

 

Plastic solutions can reduce weight, lower costs, improve safety, and have a lower environmental impact in terms of recyclability and lower CO2 emissions than steel or aluminum.

 

SABIC received an Edison Award for its thermoplastic battery housing for the Honda CR-V plug-in hybrid. The 6kg injection molded polypropylene fiberglass resin solution, a large part measuring 1.6m x 1m and 2mm thick, saved Honda 10% in weight and 10% in cost compared to a steel solution with insulation.

 

Battery pack housing

 

The battery housing is more than just a simple box, it is a large structural safety component whose role and performance requirements create opportunities for creativity and innovative engineering.

 

For the material supplier, this is reflected in its Multi-Part Integration (MPI) program, which combines multiple parts stamped from one LWB (laser welded blank) into one hot stamped part in sequence, reducing the required joining operations.

Batteries will be integrated into the body-in-white (BIW), and automakers and Tier 1 chassis suppliers are beginning to bring their chassis or BIW departments together with their battery departments in the same engineering centers to design future vehicles. This is a threat as well as an opportunity for the steel industry.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thermal runaway protection

 

A major area of ​​concern for EV batteries is heat management and protection from thermal runaway, and this is where thermoplastics shine.

Safety organization UL Solutions has developed a new rigorous thermal runaway test called UL 2596 ("Test Method for Thermal and Mechanical Properties of Battery Enclosure Materials") that subjects the material to thermal runaway involving 25 cylindrical cells (18650) in a steel battery pack.

 

The property of SABIC's thermoplastic material is that in this test, when a sample of the material was subjected to a 1000-degree Celsius flame for more than five minutes, the temperature on the side of the battery pack was less than 200 degrees Celsius, without the need for a thermal blanket required for aluminum and steel enclosures.

 

This is because the thermoplastic material developed by SABIC starts to char when it encounters fire and expands over time. This means it does not transfer heat, which is a unique property of thermoplastic materials. After a while, it acts like a turtle shell, becoming a protective layer against fire and heat transfer. Standard plastics fail this test, but plastic in millimeter-thickness passes it every time. In addition, molding the thermoplastic shell allows for creativity and increases the versatility of the material.

 

Sustainable

 

However, developing the battery pack as a structural component has significant implications for other aspects, especially for sustainable production, component life cycle, and circularity.

 

Most automakers value repairability, so the battery housing is usually accessible, removable, and replaceable. But he also acknowledged that repairability is currently lacking. Most dealers will not repair the battery but send it back to OEMs or other designated third parties for processing. When it comes to electric vehicle batteries, repairability is at least as important as recyclability in the pursuit of sustainable transportation, and it is much more efficient than recyclability.

 

The rapid development of electric vehicle battery technology is good news for consumers. It also brings exciting opportunities and challenges for automakers and suppliers.

 

 

Overall, battery aluminum shells, as an important component of new energy vehicle power battery systems, have significant advantages in lightweight, safety, and manufacturing efficiency. In the future, with the continuous advancement of technology and the continued growth of market demand, battery aluminum case solutions will play an even more important role in the new energy industry. Enterprises should actively pay attention to industry trends, seize market opportunities, and continuously improve their competitiveness to cope with increasingly fierce market competition.