The lightweight structure design of lithium battery packs aims to reduce the overall weight of the battery packs while ensuring their performance and safety. It can be approached from aspects such as material selection, structural optimization, integrated design, and manufacturing process improvement. The following is a detailed introduction:

Material selection

Battery cell material

Positive and negative electrode materials: The research and application of high energy density positive and negative electrode materials are crucial. For instance, high-nickel ternary cathode materials (such as NCM811. where the ratio of nickel, cobalt, and manganese is 8:1:1) can store more electricity under the same weight compared to traditional NCM523 materials, thereby reducing the number and weight of individual battery cells while meeting the energy demands of the battery pack. In terms of anode materials, silicon-based anode materials have a relatively high theoretical specific capacity, which can effectively enhance the energy density of batteries and facilitate lightweight design.

Diaphragm material: Select diaphragm material that is thin, light and has good performance. For instance, by adopting a new type of ceramic-coated separator, its thickness can be made thinner, while it has excellent thermal stability and mechanical strength, which can ensure the safety of the battery while reducing the weight of the separator.

Battery pack casing material

Aluminum alloy material: Aluminum alloy has the advantages of low density, high strength and corrosion resistance, and is a commonly used lightweight material for battery pack casings. For instance, 6061 aluminum alloy is widely used in aerospace, automotive and other fields. Its density is about one-third that of steel, but its strength can meet the protection requirements of battery pack casings. By optimizing the structural design of the aluminum alloy shell, such as using reinforcing ribs and other methods, the weight can be further reduced while ensuring the strength of the shell.

Composite materials: Carbon fiber composite materials possess extremely high specific strength and specific modulus, making them an ideal lightweight material. Although its cost is relatively high, it has significant advantages in high-end application scenarios where weight requirements are extremely strict. For instance, in some high-performance electric vehicle or drone battery packs, the use of carbon fiber composite material casings can significantly reduce the weight of the battery packs, enhancing the device's endurance and performance.

Structural optimization

Optimization of the layout of battery cells

Compact arrangement: Reasonably plan the arrangement of battery cells within the battery pack to make the arrangement more compact and reduce the gaps between battery cells. For instance, a honeycomb arrangement is adopted. This arrangement can accommodate more battery cells within a limited space while ensuring the heat dissipation and electrical connection performance between the battery cells.

Space utilization: Make full use of the three-dimensional space within the battery pack to avoid space waste. For instance, for battery pack Spaces with irregular shapes, irregular-shaped battery cells can be designed or customized battery brackets can be adopted to adapt to the shape of the space and enhance the space utilization rate.

The internal structure of the battery pack is simplified

Reduce support structures: By optimizing the fixation method and force analysis of individual battery cells, unnecessary support structures can be reduced. For instance, by using adhesive or welding methods to fix individual battery cells onto the battery pack casing, replacing the traditional mechanical support structure, not only can the weight be reduced, but also the overall rigidity of the battery pack can be enhanced.

Electrical connection optimization: Simplify the electrical connection circuits inside the battery pack, use thinner copper foil or aluminum foil as conductive materials, and optimize the routing and layout of the circuits to reduce their length and weight. For instance, by adopting multi-layer printed circuit board (PCB) technology and integrating electrical connection lines on the PCB board, not only can the weight be reduced, but also the reliability and stability of electrical connections can be enhanced.

Integrated design

Battery Management System (BMS) integration

Miniaturized design: Integrate and optimize the functional modules of the BMS, adopt smaller electronic components and chips, and reduce the volume and weight of the BMS. For instance, by adopting highly integrated power management chips and microcontrollers, multiple functional modules are integrated onto a single chip to achieve the miniaturization of the BMS.

Integration with battery pack: Integrate the BMS with the battery pack in a design, for instance, directly install the BMS circuit board on the battery pack housing, reducing additional connection lines and fixed structures, and further reducing the weight.

Thermal management system integration

Lightweight thermal management components: Select lightweight thermal management components, such as using lightweight heat sinks and heat pipes. For instance, aluminum alloy heat sinks are adopted to replace traditional copper heat sinks, reducing weight while ensuring heat dissipation performance.

Integration with battery pack structure: Integrate the thermal management system with the structure of the battery pack in the design. For instance, integrate the heat dissipation channels within the battery pack casing, using the battery pack casing as part of the heat dissipation component to reduce additional thermal management components and weight.

Improvement of manufacturing process

Lightweight molding process

Aluminum alloy shell forming: Advanced aluminum alloy forming processes are adopted, such as extrusion forming, die-casting forming, etc. The extrusion forming process can produce aluminum alloy profiles with complex cross-sections for making battery pack casings, which can not only ensure the strength of the casings but also reduce their weight. The die-casting process can form complex aluminum alloy shell structures in one go, reducing subsequent processing procedures and weight.

Composite material forming: For the composite material battery pack shell, vacuum injection forming, autoclave forming and other processes can precisely control the thickness and shape of the composite material, improving the quality and lightweight level of the shell.

Precision processing techniques: Precision processing techniques such as laser cutting and CNC machining are adopted to process the components within the battery pack, ensuring the dimensional accuracy and surface quality of the components, and reducing the weight and material waste of the components. For instance, using laser cutting technology to cut the tabs of battery cells can enhance the cutting accuracy and reduce the weight of the tabs.