Evolution: “a process of continual change; the process by which…things develop from preexisting forms through successive generations.” While Miriam Dictionary is referring to the evolution of living organisms, we are seeing rapid evolution in battery electric vehicle cell structure as well.
One concept gaining traction with heavyweights like Tesla and battery cell manufacturer CATL is the Cell-to-Pack (CTP) battery structure. This battery pack structure removes the clusters of cell modules, integrating the cells directly into the pack. Eliminating the modules creates more volume inside the battery housing for the cells, thereby increasing the volumetric energy density (kWh/litre) of the pack. It also results in lower weight, fewer production steps and a smaller bill of material, keeping the overall costs competitive.
However, depending on the cell format used, CTP structures have their shortcomings. For example, with cylindrical cells, to ensure the cells are protected from shock or vibration, and to protect the cells from moisture, corrosive agents or thermal propagation, a potting compound (epoxy, polyurethane, or silicone) is injected in between the battery cells. While effective, the process is slow, hard to control, expensive, and makes recycling extremely difficult.
A new solution for CTP designs
To help OEMs further capitalize on the benefits of a CTP design, Kautex developed a composite CTP housing design under its PentatonicTM product portfolio. Developed from thermoplastic composites, Kautex’s Pentatonic CTP offering solves many of the challenges present in the current cell and housing structure. Kautex’s CTP system is a structural cell holder, eliminating the need for slow, expensive potting solutions, while creating a more stable production process and reducing costs and production time. Without potting interspersed throughout the cell structure, end-of-life disassembly and recycling becomes infinitely easier to accomplish. In short, Kautex’s CTP solution provides a simplified, sustainable, and reliable solution addressing design and end-of-life challenges.
Kautex’s 80 kWh solution also improves the accuracy of cell positioning by integration positioning aids in the tray and cell holder. Additionally, when compared to metal counterparts, Pentatonic’s non-conductive and non-corrosive materials results in a reduced risk of the system short circuiting or arching. Traditionally, metal designs must add expensive coatings or coverings to achieve this objective, reducing cycle time and adding cost in the manufacturing process.
Compression and injection molding also allow for functional integration of several key factors, including thermal runaway management, battery cooling and electrical contact. Pentatonic successfully manages thermal runaway by venting gas through structures in the bottom of the tray and exiting them through an outlet. “Snake” cooling is standard in the product’s design, but other thermal cooling options are possible. Using injection molding technology, Kautex can integrate electrical isolation between contact plates and cells to prevent undesired electrical contact.
Structurally, Kautex’s solution offers a z-height maximum of 120 millimeters including an optional underbody protection, which is up to 20% smaller than standard Cell-to Module housings.
Successful Functional Testing Completed
In terms of functional testing, Pentatonic’s CTP structure meets or outperforms industry expectations:
Expertise in Compression and Injection Molding
Not only does the Pentatonic CTP system offer numerous advantages over its competitors, but Kautex is also already proving its proficiency in compression molding on its production line in Pinghu, China. Commissioned in 2022, the 5.5-ton compression molder has run numerous samplings for internal testing and customer projects. This technology complements Kautex’s existing injection molding capabilities.
Just as battery structures continue to evolve, so Kautex is evolving its design and manufacturing prowess to meet growing interest and demand.
Interested in learning more about Kautex’s latest Pentatonic innovation? Contact one of our battery experts today.
