Battery pack bottom protection plate, battery pack comprising same and vehicle

Abstract

The utility model provides a battery pack bottom protection plate which comprises a metal plate and a powder coating arranged on the surface of the metal plate, bubbles exist on the section of the powder coating, and the area of the bubbles accounts for 5%-60% of the area of the section. The coating of the bottom protection plate can improve the wear resistance of the coating while reducing noise, and the number of battery swap station circulation times of the battery pack is increased.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a battery pack bottom guard plate and a battery pack and vehicle containing the same. Background Art

[0002] In the past two years, the domestic new energy vehicle market has shown a rapid growth trend. With the rapid development of new energy, how to build a complete energy replenishment system has become an unavoidable problem. Currently, there are two ways to replenish pure electric vehicles in China. One is the more common construction of charging piles, and the other is to set up battery swap stations like NIO. On the one hand, the battery swap system has a crushing advantage in energy replenishment efficiency. For example, it is more convenient and faster for users. On the other hand, because the battery swap station manages the battery in a unified manner, all users no longer need to worry about battery degradation and safety issues. They can get a battery health check every time they swap the battery.

[0003] Currently, the warranty period for power batteries is generally eight years. Battery companies, or vehicle manufacturers that adopt charging and recharging, have little financial incentive to extend the battery life after selling the battery. However, for NIO, which adopts battery swapping and recharging, extending the battery lifespan could bring significant economic benefits. NIO currently plans to promote a 15-year worry-free battery service, increasing the power battery warranty period from eight years to 15 years. This places even stricter demands on the existing battery lifespan. However, there are currently few reports on existing technologies for extending the power battery lifespan to 15 years. Utility Model Content

[0004] The applicant has discovered that when a vehicle is driving, especially in adverse road conditions such as muddy or gravel roads, the bottom guard plate of the battery pack will inevitably encounter stone impacts, causing wear of the bottom guard plate and other components and generating noise. If the noise reduction function of the coating on the bottom guard plate of the battery pack is poor, it will lead to increased friction and vibration between the chassis and other components of the vehicle when stones hit, increasing the risk of wear, thereby affecting the service life of the battery pack. Moreover, when the battery pack is replaced and recharged, it needs to be transported by chains or rollers at the battery swap station. During the transmission process, the bottom guard plate of the battery pack will inevitably come into contact with the chains or rollers, generating friction. If the wear resistance of the coating on the bottom guard plate of the battery pack is poor, it will cause the coating to thin or even expose the metal bottom plate, increasing the risk of the metal bottom plate being exposed or even corroded or punctured by external forces, affecting the service life of the battery pack.

[0005] Currently, the bottom guard plate of the battery pack is often coated with a solvent-based polyvinyl chloride (PVC) coating to achieve corrosion resistance and stone impact resistance, but the noise reduction function and wear resistance of the coating are not considered. Taking the second-generation battery swap station of NIO as an example, the transmission components used for battery swap transmission and circulation include chains and rollers. When the battery pack circulates in the battery swap station, it will generate noise, and the bottom guard plate of the battery pack will slide and rub against the nitrile rubber chain cover and polyurethane roller. After 500-800 transmissions at the battery swap station, the PVC coating of the existing battery pack with a bottom guard plate will be worn, exposing the anti-corrosion layer underneath, thus affecting the service life of the battery pack.

[0006] In response to the above-mentioned problems, the first aspect of the present application provides a battery pack bottom guard plate, comprising a metal plate and a powder coating arranged on the surface of the metal plate, wherein bubbles exist in the cross section of the powder coating, and the total area of ​​the bubbles accounts for 5%-60% of the area of ​​the cross section.

[0007] A second aspect of the present application provides a battery pack, which includes the battery pack bottom guard plate as described in the first aspect, and the powder coating is arranged on the outer surface of the battery pack.

[0008] A third aspect of the present application provides a vehicle comprising the battery pack according to the second aspect, wherein the battery pack is mounted on the bottom of the vehicle.

[0009] The beneficial effects of this application are: the powder coating of the battery pack bottom guard plate can reduce noise, improve the wear resistance of the battery pack, increase the number of battery packs that can be used at the battery swap station, and thus increase the service life of the battery pack. In addition, the compressive pressure of the powder coating can reach 10g / mm 2 -20g / mm 2 , and can withstand the pressure of the entire battery pack during battery replacement without cracking, breakage, or peeling of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the cross-sectional structure of the bottom guard plate of an embodiment of the present utility model.

[0011] Figure 2 It is a schematic diagram of the cross-sectional structure of the bottom guard plate of comparative example 1 of the present invention.

[0012] In the figure, 1 is a metal plate, 2 is a powder coating, 3 is an anti-corrosion layer, 31 is a first anti-corrosion layer, 32 is a second anti-corrosion layer, 4 is a bubble, and 5 is a solvent-based coating. DETAILED DESCRIPTION

[0013] For the sake of clarity, this application only specifically discloses certain numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0014] In this application, unless otherwise expressly specified or limited, the terms "installed," "disposed," and "connected" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediary, or internal connections between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

[0015] Unless otherwise specified, the terms used in this application have the commonly understood meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the examples of this application).

[0016] The present application will be further described below in conjunction with specific embodiments. It should be understood that these specific embodiments are only used to illustrate the present application and are not used to limit the scope of the present application.

[0017] 1. Battery pack bottom guard plate

[0018] The first aspect of the present application provides a battery pack bottom guard plate, comprising a metal plate and a powder coating disposed on the surface of the metal plate, wherein bubbles are present in a cross-section of the powder coating, and the sum of the areas of the bubbles accounts for 5% to 60% of the area of ​​the cross-section. The applicant has discovered that by using a foaming powder coating and controlling the percentage of bubble area in the cross-section of the powder coating, the wear resistance of the coating can be improved while reducing noise and increasing the number of battery packs that can be used at battery swap stations.

[0019] In this application, "noise reduction" refers to reducing the transmission and reflection of noise, reflecting the ability of the coating to reduce the intensity and impact of noise.

[0020] In this application, "wear resistance" refers to the ability of a coating surface to resist wear and tear, which is a type of material durability. "Wear resistance" means that the coating is not easily worn under high-frequency friction, and the surface will not show phenomena such as thinning or peeling.

[0021] In this application, the "number of battery swap station transfers" refers to the number of times a battery pack completes a round trip between the battery compartment and the battery swap platform through the battery transfer and conveying system in the battery swap station. Here, the "battery transfer and conveying system" is used to transfer batteries between the battery swap station platform and the battery compartment, the "battery swap platform" is used to locate and perform battery swap operations on the vehicle, and the "battery compartment" is used to store and charge the batteries. Taking NIO's second-generation battery swap station as an example, a battery swap station transfer refers to a round trip for a battery pack through the cache position, docking position, lifting position, and battery compartment in the battery swap station.

[0022] In the present application, the bubble area ratio of the powder coating cross section can be measured by conventional testing methods in the art, or can be measured by microscope image statistics according to the method given in the embodiments of the present utility model.

[0023] In some embodiments, the percentage of the sum of the areas of the bubbles to the area of ​​the cross section is, for example, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60% or a range consisting of any two of these values. The percentage of the bubble area in the cross section of the powder coating is within the above range, which can help improve the noise reduction and wear resistance of the coating. In some preferred embodiments, the percentage of the sum of the areas of the bubbles to the area of ​​the cross section is 30%-60%. In the present application, the percentage of the bubble area in the cross section of the powder coating can be regulated by adjusting the type, amount, foaming temperature, foaming time and other conditions of the added foaming agent.

[0024] In some embodiments, the powder coating is a polyester powder coating, an epoxy powder coating, or a polyamide powder coating. Polyester powder coating, epoxy powder coating, and polyamide powder coating are more effective in reducing noise and resisting friction.

[0025] In some embodiments, the surface roughness of the powder coating is 15μm-50μm, exemplarily 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, 42μm, 45μm, 48μm, 50μm or a range consisting of any two of these values. If the surface roughness of the powder coating is too small, the battery pack will slip in the battery swap station, resulting in the battery pack being unable to circulate. If the surface roughness is too large, the coating will be more susceptible to external friction, scratches or wear, which is not conducive to improving the wear resistance of the coating. In this application, the surface roughness of the powder coating can be regulated by those skilled in the art by adjusting the spray gun pressure and angle, coating thickness, coating curing temperature and time, etc. according to the type of powder coating selected.

[0026] In some embodiments, the Shore D hardness of the powder coating is 60-100, exemplarily 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, 95, 98, 100 or a range consisting of any two of these values. The hardness of the powder coating within the above range is more conducive to improving the noise reduction function and wear resistance of the coating. In some embodiments, the Shore D hardness of the powder coating is 70-95. In this application, the Shore D hardness of the powder coating can be regulated by those skilled in the art by adjusting the coating thickness, coating curing temperature and time according to the type of powder coating selected.

[0027] In some embodiments, the thickness of the powder coating is 50 μm-600 μm, illustratively 50 μm, 80 μm, 100 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, or a range consisting of any two of these values. In this application, the thickness of the powder coating can be regulated by those skilled in the art by adjusting spraying process parameters such as spraying pressure, spraying speed, spraying distance, and nozzle size according to the type of powder coating selected.

[0028] In some embodiments, the metal plate is a steel plate or an aluminum alloy.

[0029] In some embodiments, the metal plate is made of steel plate. Compared with other metal plates, steel plate has better tensile strength and elongation, can meet the impact resistance requirements, and is beneficial to improving the protection of the battery pack, thereby increasing the service life of the battery.

[0030] In some embodiments, an anti-corrosion layer is provided between the metal plate and the powder coating to further enhance the metal plate's corrosion resistance. The anti-corrosion layer may be an electrophoretic layer or a primer layer, as long as the electrophoretic layer or primer layer effectively isolates the metal plate from the external environment of the battery pack and protects the metal plate from environmental corrosion, particularly when the powder coating is damaged, thereby extending the battery pack's service life.

[0031] In some embodiments, the anti-corrosion layer has a thickness of 20 μm-60 μm, exemplified by 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, or a range consisting of any two of these values.

[0032] In some embodiments, the anti-corrosion layer is an epoxy electrophoretic paint layer, an acrylate electrophoretic paint layer, an acrylic electrophoretic paint layer, a polyurethane electrophoretic paint layer, a polyester electrophoretic paint layer, an epoxy primer layer, a polyacrylic primer layer or a polyester primer layer. In some preferred embodiments, the anti-corrosion layer is an epoxy primer layer or an epoxy electrophoretic paint layer.

[0033] In some embodiments, the battery pack bottom guard plate includes the metal plate and a powder coating arranged on the surface of the metal plate, no anti-corrosion layer is arranged between the metal plate and the powder coating, bubbles exist in the cross section of the powder coating, and the total area of ​​the bubbles accounts for 5%-60% of the area of ​​the cross section.

[0034] In some embodiments, the battery pack bottom guard plate includes the metal plate and a powder coating arranged on the surface of the metal plate, an anti-corrosion layer is also arranged between the metal plate and the powder coating, bubbles exist in the cross section of the powder coating, and the total area of ​​the bubbles accounts for 5%-60% of the area of ​​the cross section.

[0035] In some embodiments, the thickness of the metal plate is 0.7 mm to 1.5 mm, illustratively 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, or a range consisting of any two of these values. In some embodiments, the thickness of the metal plate is 0.8 mm to 1 mm.

[0036] In some embodiments, the thickness of the battery pack bottom protective plate is 0.7 mm to 1.5 mm, exemplarily 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, or a range consisting of any two of these values. In some embodiments, the thickness of the battery pack bottom protective plate is 0.8 mm to 1 mm.

[0037] In some embodiments, the powder coating has a compressive pressure of 10 g / mm 2 -20g / mm 2 , exemplarily 10 g / mm 2 , 12g / mm 2 , 14g / mm 2 , 16g / mm 2 、18g / mm 2 , 20g / mm 2 Or a range consisting of any two of these values. When the battery pack is being replaced, the bottom guard plate must withstand the pressure of the entire battery pack. Accordingly, the powder coating on the bottom guard plate must also withstand the pressure of the entire battery pack. Failure to do so may cause cracking, damage, and peeling of the coating.

[0038] 2. Battery Pack

[0039] A second aspect of the present application provides a battery pack comprising the battery pack bottom guard plate as described in the first aspect, wherein the powder coating is disposed on the outer surface of the battery pack. The powder coating disposed on the outer surface of the battery pack can reduce noise while improving the wear resistance of the coating.

[0040] 3. Vehicles

[0041] A third aspect of the present application provides a vehicle comprising the battery pack described in the second aspect, the battery pack being mounted on the vehicle. In some embodiments, the battery pack is mounted on the bottom of the vehicle. When the battery pack is mounted, the bottom guard plate of the battery pack faces the ground.

[0042] In some embodiments, the battery pack is mounted on a chassis of the vehicle, and the battery pack bottom guard plate is disposed away from the chassis.

[0043] In some embodiments, the vehicle is a battery-swappable vehicle. In this application, a battery-swappable vehicle generally refers to any vehicle that supports battery swapping. In some embodiments, the vehicle has a structure for replacing the battery pack.

[0044] In some embodiments, the vehicle includes, but is not limited to, an electric vehicle, a hybrid electric vehicle, and a plug-in hybrid electric vehicle.

[0045] Example

[0046] In this application, the methods in the examples, unless otherwise specified, are conventional methods in the art; the raw materials, materials, and reagents in the examples are all commercially available conventional raw materials, materials, or reagents.

[0047] Test Method

[0048] 1. Thickness measurement

[0049] The thickness of powder coatings and solvent-based coatings is measured using a film thickness gauge.

[0050] Use a vernier caliper to measure the thickness of the battery pack bottom guard plate.

[0051] 2. Coating surface roughness measurement

[0052] The surface roughness of the powder coating and solvent-based coating was measured using a 3D profilometer VR-6000 at a magnification of 50 times, and the arithmetic mean height Sa was taken as the surface roughness value.

[0053] 3. Coating hardness measurement

[0054] The Shore D hardness of powder coatings and solvent-based coatings was measured using an LX-D Shore durometer.

[0055] 4. Determination of bubble area ratio in coating cross section

[0056] Mechanically cut the cross-section of the powder coating or solvent-based coating and polish it with a metallographic grinder and polisher. After polishing, photograph and measure the cross-section using a Carl Zeiss Axiolab 5 microscope. The cross-sectional area and the area of ​​each bubble are measured. The areas of all bubbles in the cross-section are summed, and the percentage of bubble area in the cross-sectional area is calculated.

[0057] 5. Measurement of foreign body impact stones

[0058] Cut the battery pack bottom guard plate from each example and comparative example into a 100 mm x 100 mm rectangular specimen and place it on a sponge, with the powder-coated or solvent-based coating facing upward. A stone was then placed 30 cm above the specimen and allowed to freely fall onto it. The decibel level of the sound at the moment the stone made contact with the specimen was recorded.

[0059] The test was conducted at a room temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The stone weighed 24.87g. Sound decibels were measured using an online digital sound level meter (Shima, model AS844+).

[0060] 6. Taber test

[0061] The battery pack bottom guard plates of each embodiment and comparative example were cut into rectangular specimens of 100 mm × 100 mm and subjected to abrasion testing using an abrasion testing machine at room temperature of 23°C ± 2°C and relative humidity of 50% ± 5%. The test method was based on the rotating rubber grinding wheel method specified in GB / T 1768, Determination of the wear resistance of paints and varnishes.

[0062] The grinding wheel and abrasion tester parameters used in the test simulate actual conditions at NIO battery swap stations. A polyurethane grinding wheel was used, with a radius of 28.25mm, a speed of 72 rpm, a thickness of 8mm, a single wheel load of 2kg, and a single wheel weight of 17.60g. The Shore D hardness of the grinding wheel was 28-38. After every 1000 revolutions of the grinding wheel, the powder coating or solvent-based coating was inspected for wear in a standard light source color-matched light box. If wear through was not achieved, the film thickness at three points along the friction mark was measured using a dry film thickness gauge and recorded. The film weight was then weighed using an electronic balance before continuing the test.

[0063] The test is terminated after the grinding wheel has run 30,000 revolutions or the coating has worn through (whichever occurs first). The reduction in thickness and weight of the powder coating or solvent-based coating is recorded to the nearest 1 μm for thickness and 0.001 g for weight. If the coating has not worn through after 30,000 revolutions, the thickness and weight loss after 30,000 revolutions are recorded. If the coating has worn through after 5,000 revolutions, the thickness and weight loss after 5,000 revolutions are recorded. "Wear through" in this context refers to the exposure of the anti-corrosion layer (if present) or the metal plate (if not present) beneath the powder coating or solvent-based coating.

[0064] Example 1

[0065] The cross-sectional structure diagram of the battery pack bottom guard plate of this embodiment is as follows Figure 1 As shown, the battery pack bottom plate comprises a metal plate 1 as a base plate, a powder coating 2 applied to the first surface of the metal plate 1, and an anti-corrosion layer 3 applied to the second surface of the metal plate 1. The metal plate is steel, the anti-corrosion layer is an epoxy electrophoretic layer, and the powder coating is an epoxy powder coating. Bubbles 4 are present in the cross-section of the powder coating. The overall thickness of the battery pack bottom plate is 0.8mm-1mm. See Table 1 for bubble area percentage, coating thickness, roughness, and hardness of the powder coating cross-section.

[0066] To prepare the battery pack underbody, mask the steel plate surface with masking tape. Epoxy electrophoretic paint is sprayed on the back of the steel plate. After drying, the masking tape is removed to obtain the underbody substrate, i.e., the steel plate with the epoxy electrophoretic paint applied to the second surface. The epoxy electrophoretic layer of the underbody substrate is masked with masking tape, and epoxy powder coating is sprayed on the other surface of the underbody substrate. After drying, the masking tape is removed to obtain the battery pack underbody.

[0067] Example 2

[0068] The battery pack bottom guard plate of this embodiment is the same as that of Example 1, except that the cross-sectional bubble area ratio, coating thickness, roughness and hardness of the epoxy powder coating are different from those of Example 1. For specific data, see Table 1.

[0069] Example 3

[0070] The battery pack bottom guard plate of this embodiment is the same as that of Example 1, except that the cross-sectional bubble area ratio, coating thickness, roughness and hardness of the epoxy powder coating are different from those of Example 1. For specific data, see Table 1.

[0071] Comparative Example 1

[0072] The cross-sectional structure diagram of the battery pack bottom guard plate of this comparative example is as follows Figure 2As shown, it includes a metal plate 1 as a base plate, a first anti-corrosion layer 31 provided on the first surface of the metal plate 1, a second anti-corrosion layer 32 provided on the second surface, and a solvent-based coating 5 provided on the anti-corrosion layer 31. The metal plate is a steel plate, the anti-corrosion layer is an epoxy electrophoretic layer, and the solvent-based coating is a polyvinyl chloride (PVC) solvent-based coating. There are bubbles 4 in the cross section of the solvent-based coating. The overall thickness of the battery pack bottom guard plate is 0.8mm-1mm. For the bubble area ratio, coating thickness, roughness, and hardness data of the solvent-based coating cross section, please refer to Table 1.

[0073] To prepare the battery pack underbody, epoxy electrophoretic paint is sprayed on the front and back of a steel plate. After drying, the underbody substrate is obtained: a steel plate with epoxy electrophoretic paint applied to both the first and second surfaces. The back of the underbody substrate is masked with masking tape, and a PVC solvent-based coating is sprayed on the other surface. After drying, the masking tape is removed to obtain the battery pack underbody.

[0074] Comparative Example 2

[0075] The battery pack bottom protective plate of this comparative example is the same as that of comparative example 1, except that the solvent-based coating 5 is not provided.

[0076] Table 1

[0077]

[0078] Table 2 records the test results of foreign body impact decibel and rotational wear (Taber test) of the bottom guard plates of each embodiment and comparative example. It can be seen that the stone impact decibel of the bottom guard plates of Examples 1-3 is relatively low, indicating that its noise reduction performance is better. Moreover, after 30,000 revolutions of the rotational wear test of the bottom guard plates of Examples 1-3, not only is the coating not exposed but the degree of coating wear is also extremely low, indicating that the battery pack containing it can increase the number of battery pack circulations during actual circulation at the battery swap station and improve the service life of the battery pack. In addition, the powder coating of the bottom guard plates of Examples 1-3 of the present invention can withstand 10g / mm 2 -20g / mm 2 The compressive pressure will not cause cracking, damage or peeling of the coating.

[0079] Table 2

[0080]

[0081] Although some exemplary embodiments of the present application have been illustrated and described, the present application is not limited to the disclosed embodiments. On the contrary, those skilled in the art will recognize that some modifications and changes may be made to the described embodiments without departing from the spirit and scope of the present application as described in the appended claims.

Claims

1. A battery pack bottom guard plate, characterized in that: The invention comprises a metal plate and a powder coating arranged on the surface of the metal plate. Bubbles exist in the cross section of the powder coating, and the total area of ​​the bubbles accounts for 5%-60% of the area of ​​the cross section.

2. The battery pack bottom guard plate according to claim 1, wherein: The percentage of the total area of ​​the bubbles to the area of ​​the cross section is 30%-60%.

3. The battery pack bottom guard plate according to claim 1 or 2, characterized in that: The powder coating is a polyester powder coating, an epoxy powder coating or a polyamide powder coating.

4. The battery pack bottom guard plate according to claim 1 or 2, characterized in that: The surface roughness of the powder coating is 15 μm-50 μm.

5. The battery pack bottom guard plate according to claim 1 or 2, characterized in that: The powder coating has a Shore D hardness of 60-100.

6. The battery pack bottom guard plate according to claim 1 or 2, characterized in that: The thickness of the powder coating is 50 μm-600 μm.

7. A battery pack, characterized in that: It includes a battery pack bottom guard plate as described in any one of claims 1 to 6, and the powder coating is arranged on the outer surface of the battery pack.

8. The battery pack according to claim 7, wherein: The compressive pressure of the powder coating is 10g / mm 2 -20g / mm 2 .

9. A vehicle, characterized in that: The vehicle comprises a battery pack according to claim 7 or 8, wherein the battery pack is installed in the vehicle.

10. The vehicle according to claim 9, wherein: The vehicle has a structure for replacing the battery pack.

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