The power battery pack is a core component as well as a critical factor affecting the overall performance of the vehicle. The weight of the battery pack accounts for 20-30% of the total vehicle weight, with production costs reaching up to 50% of the total vehicle cost. With the rapid development of the EV market, demands on power battery packs have become increasingly stringent, including requirements for extended range, high specific power and energy, and high safety and reliability. Lightweighting, as a vital pathway to enhance EV performance, is of paramount importance.
Battery pack lightweighting design primarily occurs at the system design level and the detailed design level. The ideal design should maximize weight reduction while meeting all performance requirements of electric vehicles. Here are five effective methods:
Optimization of Battery Pack Layout: Based on factors such as vehicle drive mode, center of gravity, and ground clearance, the series and parallel arrangement of battery modules is optimized to adapt to various vehicle space characteristics.
Battery Module Optimization: Starting with cell parameters and individual cell dimensions, the internal layout of the battery pack casing is optimized, and design levels are reduced to achieve maximum utilization of the casing space. For instance, Contemporary Amperex Technology Co. Limited (CATL)'s cell-to-pack (CTP) design technology directly fixes cells to the battery pack casing, increasing volume utilization and reducing production costs.
New Cell Grouping Methods: By employing large module design and integrated design, intermediate levels are reduced, and casing space utilization is improved. BYD's "blade battery" design is a prime example, where flat, large-sized cells are arranged in an array within the battery pack casing, significantly enhancing the energy density of the battery pack.
Application of Lightweight Materials: The use of lightweight materials such as aluminum alloys and composite materials has a significant weight reduction effect on the battery pack casing. Composite materials like glass fiber-reinforced plastic (SMC) and carbon fiber-reinforced polymer (CFRP) not only reduce weight but also improve insulation and ease of processing.
Limit Design: During the detailed design phase, performance optimization or later design modifications are conducted. With the aid of computer-aided design (CAE) simulation analysis technology, the design critical values are accurately located, ensuring that the structure meets design requirements while minimizing weight.
The future trend in lightweighting design lies in the optimization of multi-material battery pack structures. Lightweight materials such as magnesium alloys and composite materials have significant weight reduction effects in battery pack structural lightweighting design. However, there are some shortcomings in the application of lightweight materials in battery pack structural design, such as a lack of battery pack structures that are both performance and lightweighting effective, and insufficient research on multi-material selection methods for battery packs. Future research should focus more on the rational application of materials and multi-material design methods that consider performance constraints.
Battery pack lightweighting is not just a technical issue but a systems engineering issue. It involves multiple fields such as material science, mechanical engineering, and electronic engineering, requiring interdisciplinary collaboration and innovation. With the continuous emergence of new materials and technologies, we can anticipate that battery pack lightweighting will bring more possibilities for performance enhancement and cost reduction in electric vehicles. This will also promote the electric vehicle industry to develop in a more environmentally friendly and economical direction.
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