Use of a high-voltage battery

Abstract

High-voltage battery with multiple cells (10) and at least one pressure cushion (11) arranged between the cells (10), characterized by the following feature: The pressure pad (11) is traversed by tubes made of aluminium composite foil (12).

Description

[0001] The present invention relates to the use of a high-voltage battery. State of the art

[0002] In the field of high-voltage batteries (HVB) for electric vehicles, the efficient and safe arrangement and protection of the individual battery cells are of crucial importance. The battery cells are typically combined in a so-called battery stack, in which the individual cells are separated from each other by cell interlayer materials. These materials fulfill several critical functions that are essential for the battery's performance and longevity.

[0003] The primary function of the cell spacer is to compensate for tolerances through compression. This allows for adaptation to minor size differences between individual cells and ensures a firm and secure fit of the cells within the battery pack. Another function of the cell spacer is to apply defined preload forces to the cells to stabilize the overall battery pack.

[0004] Another important aspect is the accommodation of volume changes in the battery cell, which depend on both the state of charge (SoC) and the aging of the battery cell (state of health, SoH). These volume changes must be compensated for to maintain the mechanical integrity and electrical connections within the battery pack.

[0005] Additionally, the cell interlayer materials serve as electrical and thermal insulation between the battery cells. This insulation prevents short circuits and supports heat distribution within the battery pack, even under high power demands.

[0006] In an immersion-cooled HVB, the flow of the cooling medium between the battery cells also plays an important role. This flow improves heat dissipation and contributes to a uniform temperature of the battery pack.

[0007] Up to now, foams, elastomers, or felts have been predominantly used as intercellular materials. These materials offer a certain degree of cushioning and insulation.

[0008] US 2021 / 0 167 444 A1 and US 2022 / 0 263 159 A1 each disclose the subject matter of the preamble of claim 1.

[0009] From DE 10 2021 115 536 A1 a compressible separating element for insertion between two battery cells of a battery which has a gas chamber is known.

[0010] FR 3 138 738 A1 discloses compressible spacer cushions for insertion between two battery cells of a battery. These are filled with a fluid, in particular air.

[0011] DE 10 2021 206 937 A1 discloses a pressure equalization element that is at least partially compressible and can be inserted between two battery cells to clamp them. The pressure equalization element has surface structures that are identical to corresponding structures on the battery cells. Disclosure of the invention

[0012] One problem is that known cell interlayer materials exhibit significant settling and creep effects over time. These material changes are due to the mechanical stresses and thermal cycles to which they are subjected during normal battery operation. Such settling and creep effects cause the material to lose elasticity and permanently reduce its thickness. This has a direct impact on the functionality of the battery system: mechanical stability can be compromised, the uniform preload force reduced, and the efficient thermal insulation between the cells deteriorates with age.

[0013] Another problem arises from the chemical and physical interaction of the cell interlayer materials, particularly in immersion-cooled battery systems. Conventional materials can react with or be affected by the cooling fluids, leading to further material degradation. This not only negatively impacts the battery's lifespan and performance but can also create maintenance and safety risks.

[0014] The flow of the cooling medium between the cells is also often insufficient in conventional systems. While the materials used do offer pores or channels for the flow of the cooling medium, these are not always uniform or adequately sized. An uneven temperature distribution within the battery pack can impair the efficiency and lifespan of the battery cells and increase the risk of overheating.

[0015] The problem described is solved by a use according to claim 1.

[0016] This approach offers the advantage of significantly reducing material fatigue caused by settling and creep effects. This gives a battery according to the invention a stable mechanical structure, as its components retain their elasticity and thickness throughout the battery's entire life cycle. In particular, uniform preload forces are ensured, which improves the electrical connection between the cells.

[0017] A further advantage arises from the improved chemical and physical resistance to cooling media. The materials used according to the invention do not interact with typical cooling fluids and exhibit higher resistance to degradation. This extends the battery's service life.

[0018] Furthermore, heat dissipation and uniform temperature control of the battery pack are optimized. The flow of the cooling medium between the cells is cleverly designed, enabling more even cooling. This results in a more stable temperature distribution within the battery pack, which increases the performance and lifespan of the cells and reduces the risk of overheating.

[0019] Overall, these improvements contribute to greater reliability and efficiency of the high-voltage battery by strengthening the mechanical and thermal integrity of the entire system.

[0020] Further advantageous embodiments of the invention are specified in the dependent patent claims. Brief description of the drawings Fig. Figure 1 shows the longitudinal section of a conventional HVB ​​in its delivery state (100% SoH). Fig. Figure 2 shows a corresponding cross-section of the HVB at the end of their lifespan (50% SoH). Fig. Figure 3 shows a single HVB cell clamped between two pressure pads in its delivery state. Fig. Figure 4 shows the single cell at the end of its life. Fig. Figure 5 illustrates, using a family of curves, the dependence of the pressure exerted by a conventional pressure pad on its relative compression, as well as the material-specific hysteresis between compression and decompression. Fig. Figure 6 shows the cross-section of the pressure pad arranged between two cells of an HVB according to the invention. Fig. Figure 7 shows the longitudinal section of the same pressure pad in the plane of its sealing seams. Fig. 8 shows one of the Fig. 1 corresponding longitudinal section of the HVB according to the invention in the delivery state. Fig. 9 shows one of the Fig. 2 corresponding longitudinal section of the HVB according to the invention at the end of its life. Fig. Figure 10 shows in a common coordinate system the pressure distribution of a conventional pressure pad and a pad filled with air according to the invention in comparison. Fig. Figure 11 illustrates, using a family of curves obtained from over 1,000 test cycles, the dependence of the pressure exerted by the cushion according to the invention on its thickness. Embodiments of the invention

[0021] The Fig. 1 and Fig. Figure 2 shows the longitudinal section of a conventional HVB ​​in its delivered state and at the end of its service life. Pressure pads (11) are arranged between the individual cells (10) of the HVB, serving both mechanical stabilization and thermal insulation. As shown in the detailed illustrations according to Figure 2, the following are also shown: Fig. 3 and Fig. As can be easily seen from Figure 4, these conventional pressure pads (11) experience significant material fatigue over the lifetime of the HVB, which reduces their preload force and thus severely impairs the mechanical and electrical integrity of the overall system.

[0022] Fig. Figure 5 illustrates, using a family of curves obtained over six test cycles, the dependence of the pressure exerted by the conventional pressure pad (11) on its relative compression. It becomes apparent that the pressure increases with increasing compression. However, the characteristic curve changes with each repetition of the test, as the elastomer settles with increasing compression.

[0023] The Fig. 6 and Fig. Figure 7 shows the cross-sectional and longitudinal sections of a pressure cushion used according to the invention. This cushion consists of an aluminum composite foil (12) which is divided into a plurality of tube-like chambers by sealing seams (14). These chambers are filled with air or another gas (13) and thus form an air cushion. The sealing seams (14) also define channels that enable efficient flow of the coolant (16) between the cells (10).

[0024] Fig. 8 and Fig. 9 show analogous to Fig. 1 and Fig. 2. The longitudinal section of a high-pressure air cushion (HVB) with pressure cushions used according to the invention is shown in the delivered state and at the end of its service life. It is evident that the air cushions largely retain their original shape and functionality even after a long period of use. This is due to the controlled and repeatable compression of the air cushions, which is based on the ideal gas law and allows for precise adjustment of the compressibility.

[0025] Fig. Figure 10 compares the pressure distribution of a conventional pressure cushion (17) and an air-filled cushion (18) according to the invention in a common coordinate system. It is evident that the air cushion provides a significantly more homogeneous pressure distribution over the entire surface of the cushion. This is due to the global pressure equalization created by the connection of the individual air chambers.

[0026] Fig. Figure 11 shows results from long-term tests over 1,000 cycles. Fig. Figure 11 illustrates the dependence of the pressure exerted by the cushion according to the invention, in megapascals, on its thickness in millimeters. It is evident that this characteristic curve remains largely unchanged even with repeated compression and decompression. Reference symbol list 10 cells 11 pressure pads 12 (aluminium) composite foil 13 Air, Gas 14 Seal seam 16 Coolant 17 Pressure distribution conventional cell interlayer 18 Pressure distribution pressure cushion used according to the invention

Claims

[1] Use of a high-voltage battery with several cells (10) and at least one pressure cushion (11) arranged between the cells (10), which is structured such that the high-voltage battery is traversed between the cells (10) by channels carrying coolant (16) and is traversed by tubes made of aluminium composite foil (12) which have sealing seams (14) running parallel between the tubes, along which the channels between the tubes extend, characterized by the following characteristics: - the high-voltage battery is immersion-cooled, - the coolant (16) flows through the channels past the cells (10) and - Any swelling of the cells (10) is compensated for by the pressure cushion (11) by compressing its tubes. [2] Use according to claim 1, characterized by the following characteristic: - the hoses contain a gas mixture, especially air (13). [3] Use according to claim 2, characterized by the following characteristics: - the cells (10) have a consistent height perpendicular to the tubes and - the hoses are fluidically connected to each other in such a way that the pressure cushion (11) has a uniform pressure distribution over its height. [4] Use according to any one of claims 1 to 3, characterized by one of the following characteristics: - the hoses each have a circular cross-section or - the hoses each have an oval cross-section.

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