LANXESS launches new PBT compound for battery components in electric cars

Specialty chemicals company LANXESS has developed a new  compound called Pocan AF4130 in collaboration with HELLA KGaA Hueck &  Co., based in Lippstadt, Germany. It serves as a housing material for a  battery management unit (BMU) and two cell monitoring units (CMU).

The blend of polybutylene terephthalate (PBT) and  acrylic ester-styrene-acrylonitrile (ASA) contains 30 percent by weight glass  fibers and a halogen-based flame retardance package. “The particular  advantages of the material are its extremely low warpage and shrinkage,  combined with its high flame retardance. We see great potential for  application in precision components for vehicle battery systems,” says Marc  Marbach, head of Sales Segments E&E in the LANXESS High Performance  Materials (HPM) business unit. It took just two-and-a-half years to go from  the initial idea to extensive testing and finally to use in full-scale production.  

HELLA fabricates the BMU and CMUs for a German  manufacturer of battery systems for motor vehicles. The very flat devices  currently are used in the lithium-ion battery system of a German compact car.  

Low tolerances

The housings of the BMU and CMUs have large, flat  surfaces as well as complex geometries along the edges and on the inside.  Thanks to their innovative design, they can be injection molded  cost-effectively as single components. The contact pins for the connectors  must not bend when the housings are mounted on the printed circuit boards.  The tolerances for the spacing between the connector mounts and the cut-outs  for the pins are therefore extremely close. “This is precisely where the  outstanding dimensional stability of our blend Pocan AF4130 pays off,”  explains Marbach.

UL 94 5VA- and UL f1-listed

As required for this application, the material achieves  the best classification of V-0 (0.75 millimeters) in UL 94 fire testing by  the U.S. testing organization Underwriters Laboratories Inc. It further is  listed on the UL Yellow Card with a good classification of UL 94 5VA (1.5  millimeters). The material is destined for the injection molding of  flame-retardant housing components. It additionally has been given a UL f1  listing for use in outdoor applications involving exposure to UV light and  water. “Our compound thus has a good chance of also being used for electrical  components such as photovoltaic plugs and sockets,” says Marbach.

Low volatile and condensable emissions

Surfaces made of this thermoplastic are very  low-emission, as demonstrated by thermal desorption analyses conducted by  LANXESS in accordance with VDA 278 (German Association of the Automotive  Industry). “It is therefore also suitable for many motor vehicle applications  requiring very low volatile and condensable emissions, such as components for  the automotive interior,” says Marbach.

Good resistance to common battery electrolytes

The blend is highly resistant to typical media used in  motor vehicles, such as fuels, oils, cleansers and car care products, as  proven in extensive media storage tests conducted by LANXESS for HELLA in  accordance with the supply specification LV 124, used by many automotive  manufacturers. It also displays good resistance to an electrolyte widely used  in lithium-ion batteries. The corresponding test was additionally conducted  under load in compliance with DIN EN 22088-3. “No cracks were evident in the  samples even after 1,000 hours of exposure,” explains Marbach.

Comprehensive HiAnt services

LANXESS provided HELLA with extensive support in  developing the housing components. These services are part of its HiAnt  customer service package. For example, HPM delivered suggestions for optimal  component design, provided all the characteristic material data required for  the computer-aided design of the housing parts to meet expected loads and for  the mold flow analyses, and supported the initial injection molding trials.  The specialty chemicals company further determined the blend’s halogenide  content for HELLA by means of ion chromatography and conducted odor testing  to VDA 270.