Bottom protection plate for battery pack, battery pack comprising same, and vehicle

Abstract

Provided in the present application are a bottom protection plate for a battery pack, a battery pack comprising same, and a vehicle. The bottom protection plate for a battery pack comprises a metal plate and a powder coating arranged on a surface of the metal plate, wherein the thickness of the powder coating is 50-400 μm, the surface roughness of the powder coating is 15-60 μm, and the coefficient of dynamic friction between the powder coating and nitrile rubber is greater than or equal to 0.5. The solution can solve the problem of slipping caused by sliding friction during the circulation of the battery pack equipped with the powder-coating-containing bottom protection plate in a battery swap station, and can further improve the wear resistance of the battery pack and prolong the service life of the battery pack.

Description

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

[0001] Cross-references to related documents

[0002] The present application claims priority to Chinese Patent Application No. CN202410993372.2, filed on July 24, 2024, entitled “Battery pack bottom protection plate, battery pack containing same and vehicle”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the technical field of batteries, and specifically relates to a battery pack bottom protection plate, a battery pack containing same and a vehicle. BACKGROUND

[0004] In the past two years, the new energy vehicle market has shown a rapid growth trend. With the rapid development of new energy, the energy supplement system has become a problem that cannot be avoided. At present, there are two ways to supplement energy for pure electric vehicles, one is to build charging piles, and the other is to layout battery swap stations like NIO. On the one hand, battery swap has a crushing advantage in energy supplement efficiency, such as being more convenient and faster, on the other hand, due to the unified management of battery swap stations, all users no longer need to worry about battery degradation and safety problems, and can get a battery check every time they swap batteries.

[0005] At present, the warranty period of power batteries is generally 8 years, and battery companies or vehicle companies that take the charging and energy supplement route have no great economic incentive to improve the service life of batteries after selling batteries or vehicles. For NIO, which takes the battery swap energy supplement route, if the service life of the battery can be improved, it can bring huge economic benefits. At present, NIO plans to promote 15-year worry-free battery service, and to increase the warranty period of power batteries from 8 years to 15 years, which puts higher requirements on battery packs and battery swap stations. However, there is currently little prior art reporting on this aspect.

[0006] SUMMARY

[0007] The applicant found that when the battery pack is used for battery swap energy supplement, it needs to be transferred through a chain or a roller in the battery swap station, and the battery pack bottom protection plate will inevitably come into contact with the chain or the roller during the transfer process, causing friction. If the wear resistance of the coating of the battery pack bottom protection plate is poor, it will cause the coating to thin out or even expose the metal bottom plate, increasing the risk of metal bottom plate exposure and corrosion or external force penetration, affecting the service life of the battery pack.

[0008] Currently, the battery pack bottom protection plate coating commonly used is a solvent-based polyvinyl chloride (PVC) coating to achieve the effects of corrosion resistance and stone impact resistance, without considering the wear resistance of the coating. Taking the second-generation battery swap station of NIO as an example, the conveying components used for battery swap transmission and circulation include chains and rollers. When the battery pack circulates in the battery swap station, the battery pack bottom protection plate will slide and rub against the nitrile rubber chain cover and the polyurethane roller. The existing battery pack with a PVC-coated bottom protection plate will be worn out after 500-800 times of battery swap circulation in the battery swap station, exposing the underlying corrosion-resistant layer and affecting the service life of the battery pack. If the service life of the battery pack is to be improved to 15 years, the battery pack ideally needs to circulate 1500 times in the battery swap station without the bottom protection plate coating being worn out, according to the normal usage frequency.

[0009] The applicant found that, compared with a battery pack with a solvent-based coating bottom protection plate, a battery pack with a powder coating bottom protection plate has better wear resistance and can improve the service life of the battery pack, but when the battery is swapped and charged, the battery pack bottom protection plate is more likely to slide and rub against the nitrile rubber chain cover and the polyurethane roller, causing skidding, thereby affecting the circulation efficiency of the battery pack, especially the sliding and rubbing skidding phenomenon on the polyurethane roller.

[0010] To solve the problem of sliding and rubbing skidding of the battery pack with a powder coating bottom protection plate when circulating in the battery swap station, the present application provides a battery pack bottom protection plate that does not slide and rub against the nitrile rubber chain cover and the polyurethane roller when circulating in the battery swap station through the battery transfer conveying system.

[0011] The first aspect of the present application provides a battery pack bottom protection plate, comprising a metal plate and a powder coating disposed on the surface of the metal plate, the thickness of the powder coating is 50-400 μm, the surface roughness of the powder coating is 15-60 μm, and the dynamic friction coefficient of the powder coating with nitrile rubber is ≧0.5.

[0012] The second aspect of the present application provides a battery pack comprising the battery pack bottom protection plate of the first aspect, wherein the powder coating is disposed on the outer surface of the battery pack.

[0013] The third aspect of the present application provides a vehicle comprising the battery pack of the second aspect, wherein the battery pack is installed at the bottom of the vehicle.

[0014] The beneficial effects of the present application are: the present application solves the problem of sliding friction skidding of the battery pack with powder coating bottom protection plate during circulation in the battery swap station, improves the circulation efficiency of the battery swap station, and the powder coating on the bottom protection plate also improves the wear resistance of the battery pack, so that the battery pack can withstand the continuous scraping friction caused by periodic sliding with the transmission chain or roller during the battery swap process, increases the circulation frequency of the battery pack in the battery swap station, and improves the service life of the battery pack. Moreover, the pressure of the powder coating can reach 10g / mm 2 -20g / mm 2 , can withstand the pressure of the entire battery pack during battery swap without cracking, breaking, peeling and other phenomena. DETAILED DESCRIPTION

[0015] For the sake of brevity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with any other lower limit to form a range not explicitly recited, and likewise any upper limit can be combined with any other upper limit to form a range not explicitly recited. Further, each individual disclosed point or single numerical value can itself be combined with any other point or single numerical value to form a range not explicitly recited, either as a lower limit or an upper limit, or with other lower limits or upper limits.

[0016] In the present application, the terms indicating the direction or position relationship of "upper", "lower", "inner", "outer" and the like are only for the convenience of description, and are not indicative or suggestive of the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or suggesting relative importance.

[0017] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0018] Unless otherwise specified, the terms used in the present application have the commonly understood meanings understood by those skilled in the art. Unless otherwise specified, the values of each parameter mentioned in the present application can be measured by various measurement methods commonly used in the art (for example, the test can be carried out according to the method given in the examples of the present application).

[0019] The present application will be further described below in conjunction with the specific embodiments. It should be understood that these specific embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0020] I. Battery pack bottom guard plate

[0021] 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, the thickness of the powder coating is 50-400 μm, the surface roughness of the powder coating is 15-60 μm, and the dynamic friction coefficient of the powder coating with nitrile rubber is ≧0.5. The applicant found that by matching the thickness, surface roughness and dynamic friction coefficient of the powder coating with nitrile rubber, the wear resistance of the coating can be improved, the number of times of circulation in the battery swap station can be increased, and the problem of sliding friction slip of the battery pack with the bottom guard plate containing the powder coating when circulating in the battery swap station can be improved.

[0022] In the present application, the "dynamic friction coefficient" refers to the ratio of the friction force generated between the battery pack bottom guard plate and the transmission component to the pressure perpendicular to the contact surface of the battery pack bottom guard plate and the transmission component in the state of relative motion.

[0023] In the present application, "slip" describes sliding friction slip, which specifically refers to the situation that when the friction force between the battery pack bottom guard plate and the transmission component of the battery swap station cannot completely offset the relative motion trend between them, the battery pack slides.

[0024] In the present application, "wear resistance" refers to the ability of the coating surface to resist wear, which is a kind of durability of a material. "Wear-resistant" means that the coating is not easy to wear under high-frequency friction, and the surface will not appear phenomena such as thickness thinning and skin peeling.

[0025] In the present application, "the number of times of circulation in the battery swap station" refers to the number of times of circulation of the battery pack in the battery swap station through the battery transfer conveying system to complete the round trip between the battery compartment and the battery swap platform. Here, the "battery transfer conveying system" is used to transfer the battery between the battery swap station platform and the battery compartment, the "battery swap platform" is used for positioning and battery replacement operation of the vehicle, and the "battery compartment" is used for storage and charging of the battery. Taking the NIO second-generation battery swap station as an example, one circulation in the battery swap station means that the battery pack passes through the buffer position, the connection position, the lifting position and the battery compartment once in the battery swap station.

[0026] In some embodiments, the powder coating has a dynamic friction coefficient with nitrile rubber of 0.50, 0.52, 0.55, 0.58, 0.60, 0.62, 0.65, 0.68, 0.70, 0.72, 0.75, 0.78, 0.80, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, or a range between any two of these values. In some embodiments, the powder coating has a dynamic friction coefficient with nitrile rubber of 0.55-0.85. If the dynamic friction coefficient is too small, the friction between the battery pack bottom guard and the upper cover of the battery swap station conveying chain will not be sufficient to provide sufficient resistance, resulting in sliding on the contact surface and failing to maintain stable movement. If the dynamic friction coefficient is too large, the battery pack bottom guard and the upper cover of the battery swap station conveying chain will be worn, thereby reducing the service life of the battery pack and increasing the wear and tear of the parts of the battery swap station. In some embodiments, the powder coating has a dynamic friction coefficient with nitrile rubber of 0.60-0.80. In this application, the dynamic friction coefficient between the powder coating and nitrile rubber can be adjusted by adjusting the type of powder coating, the thickness of the coating, the surface roughness of the coating, or the addition of additives, etc.

[0027] In some embodiments, the powder coating has a thickness of 50-400 pm, for example 50 pm, 60 pm, 80 pm, 100 pm, 120 pm, 140 pm, 160 pm, 180 pm, 200 pm, 220 pm, 240 pm, 260 pm, 280 pm, 300 pm, 350 pm, 400 pm, or a range between any two of these values. If the thickness of the powder coating is too large, multiple spraying of the powder coating is required, which increases the cost, may increase the friction coefficient, increase the risk of slipping, and may also result in incomplete curing of the coating, thereby adversely affecting the wear resistance of the coating. If the thickness of the powder coating is too small, the wear resistance of the battery pack cannot be effectively improved, which is not conducive to increasing the number of battery pack swap station transactions, thereby affecting the service life of the battery pack, and the wear of the thin coating surface may change the surface properties of the coating, increasing the risk of slipping. In some embodiments, the thickness of the powder coating is 50-300 pm. In some embodiments, the thickness of the powder coating is 60-280 pm. In this application, the thickness of the powder coating can be adjusted by adjusting the spraying process parameters such as spraying pressure, spraying speed, spraying distance, and nozzle size according to the type of powder coating selected by those skilled in the art.

[0028] In some embodiments, the powder coating has a surface roughness of 15-60 μm, illustratively 15 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 45 μm, 48 μm, 50 μm, 52 μm, 55 μm, 58 μm, 60 μm, or a range defined by any two of these values. If the surface roughness of the powder coating is too small, the friction coefficient will be reduced, causing the battery pack to slip when it is transferred in the battery swap station. If the surface roughness of the powder coating is too large, the coating will be more susceptible to external friction, scratching, or wear, thereby adversely affecting the wear resistance of the coating. In some embodiments, the powder coating has a surface roughness of 15-50 μm. In the present application, the surface roughness of the powder coating can be adjusted by adjusting the type of powder coating, the pressure and angle of the spray gun, the coating thickness, the coating curing temperature and time, the addition of additives, and the like. Commonly used additives include inorganic particle powder additives such as silica, calcium carbonate, aluminum silicate, aluminum oxide, silicon carbide, and the like, and foaming additives.

[0029] In some embodiments, the powder coating has a static friction coefficient with nitrile rubber of > 0.6, illustratively 0.60, 0.62, 0.65, 0.68, 0.70, 0.72, 0.75, 0.78, 0.80, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, or a range defined by any two of these values. In some embodiments, the powder coating has a static friction coefficient with nitrile rubber of 0.60-0.98. In some embodiments, the powder coating has a static friction coefficient with nitrile rubber of 0.60-0.90. In some embodiments, the powder coating has a static friction coefficient with nitrile rubber of 0.65-0.85. If the static friction coefficient is too large, the battery pack bottom guard and the upper cover of the transmission chain of the battery swap station will be worn, thereby reducing the service life of the battery pack and increasing the loss of parts of the battery swap station. In the present application, the static friction coefficient between the powder coating and nitrile rubber can be adjusted by adjusting the type of powder coating, the coating thickness, the surface roughness of the coating, or the addition of additives, and the like.

[0030] In the present application, the "static friction coefficient" refers to the ratio of the friction force generated by the battery pack bottom guard and the transmission component in a relatively static state to the pressure perpendicular to the contact surface of the battery pack bottom guard and the transmission component of the battery swap station.

[0031] In some embodiments, the powder coating is selected from one or more of polyester powder coatings, epoxy powder coatings, and polyamide powder coatings. In some embodiments, the powder coating is a polyester powder coating, an epoxy powder coating, or a polyamide powder coating.

[0032] In some embodiments, the Shore hardness D of the powder coating is 50-95, exemplarily a range of 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, 95, or any combination of these values. The applicant has found that the hardness of the powder coating is also related to its abrasion resistance; a Shore hardness D within the aforementioned range can better improve the abrasion resistance of the coating and increase the number of battery pack cycles at the swapping station. If the powder coating is too hard, it will wear down the components of the swapping station; if the hardness is too low, it will be detrimental to further improving the abrasion resistance of the battery pack. In some embodiments, the Shore hardness D of the first powder coating is 70-95. In this application, those skilled in the art can control the Shore hardness D of the powder coating by adjusting the type of powder coating, coating thickness, coating curing temperature and time, and adding additives. Commonly used additives include inorganic particulate powder additives such as silica, calcium carbonate, aluminum silicate, alumina, and silicon carbide, as well as foaming additives.

[0033] In some embodiments, the metal plate is a steel plate or an aluminum alloy.

[0034] In some embodiments, the metal plate is made of steel. Compared with other metal plates, steel plates have better tensile strength and elongation, which can meet the impact resistance requirements, improve the protection of the battery pack, and thus extend the battery's service life.

[0035] In some embodiments, an anti-corrosion layer is further provided between the metal plate and the powder coating to further improve the corrosion resistance of the metal plate. The anti-corrosion layer can be an electrophoretic layer or a primer layer, as long as it can effectively isolate the metal plate from the external environment of the battery pack and protect the metal plate from environmental corrosion, especially when the powder coating is damaged, thereby protecting the metal plate from external environmental corrosion and extending the service life of the battery pack.

[0036] In some embodiments, the anti-corrosion layer is an epoxy electrophoretic coating layer, an acrylic electrophoretic coating layer, an acrylic electrophoretic coating layer, a polyurethane electrophoretic coating layer, a polyester electrophoretic coating 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 coating layer.

[0037] In some embodiments, the thickness of the anti-corrosion layer is 20μm-60μm, exemplarily 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm or any combination of these values.

[0038] In this application, the thickness of the electrophoretic layer, which serves as the anti-corrosion layer, can be controlled by adjusting the electrophoresis time, electric field strength, solution concentration, pH value, etc. Similarly, the thickness of the primer layer, which serves as the anti-corrosion layer, can be controlled by adjusting the spraying speed, spraying distance, nozzle size, and shape, etc.

[0039] In some embodiments, the battery pack bottom cover includes the metal plate and a powder coating disposed on the surface of the metal plate. No anti-corrosion layer is disposed between the metal plate and the powder coating. The powder coating is selected from epoxy powder coating. The thickness of the powder coating is 50μm-400μm. The surface roughness of the powder coating is 15μm-60μm. The dynamic friction coefficient between the powder coating and nitrile rubber is 0.5-0.95. The static friction coefficient between the powder coating and nitrile rubber is 0.6-0.98.

[0040] In some embodiments, the battery pack bottom cover includes the metal plate and a powder coating disposed on the surface of the metal plate. No anti-corrosion layer is disposed between the metal plate and the powder coating. The powder coating is selected from epoxy powder coating. The thickness of the powder coating is 50μm-400μm. The surface roughness of the powder coating is 15μm-60μm. The dynamic friction coefficient between the powder coating and nitrile rubber is 0.5-0.95. The static friction coefficient between the powder coating and nitrile rubber is 0.6-0.98. The Shore hardness D of the powder coating is 50-95.

[0041] In some embodiments, the battery pack bottom cover includes the metal plate and a powder coating disposed on the surface of the metal plate. An anti-corrosion layer is further disposed between the metal plate and the powder coating. The powder coating is selected from polyester powder coating, epoxy powder coating and polyamide powder coating. The thickness of the powder coating is 50μm-400μm, the surface roughness of the powder coating is 15μm-60μm, the dynamic friction coefficient between the powder coating and nitrile rubber is 0.5-0.95, the static friction coefficient between the powder coating and nitrile rubber is 0.6-0.98, and the anti-corrosion layer is an epoxy primer layer or an epoxy electrophoretic paint layer. The thickness of the anti-corrosion layer is 20μm-60μm.

[0042] In some embodiments, the battery pack bottom cover includes the metal plate and a powder coating disposed on the surface of the metal plate. An anti-corrosion layer is further disposed between the metal plate and the powder coating. The powder coating is selected from polyester powder coating, epoxy powder coating and polyamide powder coating. The thickness of the powder coating is 50μm-400μm, the surface roughness of the powder coating is 15μm-60μm, the dynamic friction coefficient between the powder coating and nitrile rubber is 0.5-0.95, the static friction coefficient between the powder coating and nitrile rubber is 0.6-0.98, the Shore hardness D of the powder coating is 50-95, and the anti-corrosion layer is an epoxy primer layer or an epoxy electrophoretic paint layer, with a thickness of 20μm-60μm.

[0043] In some embodiments, the thickness of the metal plate is 0.7 mm to 1.5 mm, exemplarily a range of 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, or any combination of these values. In some embodiments, the thickness of the metal plate is 0.8 mm to 1 mm.

[0044] In some embodiments, the thickness of the battery pack bottom protector is 0.7mm-1.5mm, exemplarily a range of 0.7mm, 0.9mm, 1.1mm, 1.3mm, 1.5mm, or any combination of these values. In some embodiments, the thickness of the battery pack bottom protector is 0.8mm-1mm.

[0045] In some embodiments, the powder coating is subjected to a pressure of 10 g / mm². 2 -20g / mm 2 For example, 10 g / mm 2 12g / mm 2 14g / mm 2 16g / mm 2 18g / mm 2 20g / mm 2 Or a range of any two of these values. When the battery pack is being swapped, the bottom protective plate must withstand the pressure of the entire battery pack, and correspondingly, the powder coating on the bottom protective plate must also withstand the pressure of the entire battery pack; otherwise, cracking, damage, and peeling of the coating may occur.

[0046] II. Battery Pack

[0047] A second aspect of this application provides a battery pack including a bottom protective plate as described in the first aspect, wherein the powder coating is disposed on the outer surface of the battery pack. The powder coating on the outer surface of the battery pack can solve the problem of slippage during battery swapping at a battery swapping station and can also improve the wear resistance of the battery pack.

[0048] III. Vehicles

[0049] A third aspect of this application provides a vehicle comprising a battery pack as 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. In the mounted state, the battery pack bottom guard plate faces the ground.

[0050] In some embodiments, the battery pack is mounted on the chassis of the vehicle, and the battery pack underbody is disposed away from the chassis.

[0051] In some embodiments, the vehicle is a battery-swapping vehicle. In this application, "battery-swapping vehicle" refers to all vehicles that support battery swapping functionality. In some embodiments, the vehicle has a structure for replacing the battery pack.

[0052] 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.

[0053] Example

[0054] In this application, the methods in the embodiments, unless otherwise specified, are conventional methods in the art; the raw materials, materials, and reagents in the embodiments, unless otherwise specified, are commercially available conventional raw materials, materials, or reagents.

[0055] Test methods

[0056] 1. Determination of dynamic friction coefficient

[0057] The dynamic friction coefficient between powder coating and nitrile rubber was measured in accordance with the national standard GB / T 10006-2021, "Determination of the coefficient of friction of plastic films and sheets".

[0058] 2. Determination of static friction coefficient

[0059] The static friction coefficient between powder coating and nitrile rubber was measured in accordance with the national standard GB / T 10006-2021, "Determination of the coefficient of friction of plastic films and sheets".

[0060] 3. Thickness Measurement

[0061] The thickness of powder coating, electrophoretic layer, primer layer and solvent-based coating was measured using a film thickness gauge.

[0062] The thickness of the battery pack bottom protective plate was measured using vernier calipers.

[0063] 4. Coating hardness test

[0064] The Shore D hardness of powder coatings and solvent-based coatings was measured using an LX-D Shore hardness tester.

[0065] 5. Coating surface roughness measurement

[0066] The surface roughness of powder coatings and solvent-based coatings was measured using a VR-6000 3D profile measuring instrument at 50x magnification. The arithmetic mean height Sa was taken as the surface roughness value. The measurement accuracy in the Z direction was 0.4 μm, and the measurement accuracy in the X and Y directions was 0.5 μm.

[0067] 6. Coating Rotational Abrasion Test (Taber test)

[0068] The battery pack bottom protection plates of each embodiment and comparative example were cut into 100mm × 100mm rectangular specimens. The abrasion resistance of the powder coating and solvent-based coating was tested using an abrasion testing machine at room temperature (23℃ ± 2℃) and relative humidity (50% ± 5%). At least three specimens were prepared for each embodiment and comparative example for testing, and the average value of the test results was taken. The test method referred to GB / T1768, "Determination of Abrasion Resistance of Paints and Varnishes: Rotating Rubber Grinding Wheel Method".

[0069] The grinding wheel and wear test parameters used in the test simulated the actual conditions of a NIO battery swapping station. A polyurethane grinding wheel was used, with a rotation radius of 28.25 mm, a rotation speed of 72 r / min, a wheel thickness of 8 mm, a single wheel load of 2 kg, and a Shore hardness (D) of 28-38. Every 1000 revolutions of the grinding wheel, the wear of the powder coating or solvent-based coating was checked in a standard light source color matching box. If the coating was not worn through, the film thickness at three points along the friction marks was measured using a dry film thickness gauge and recorded. The film weight was then measured using an electronic balance, and the test continued.

[0070] The test is stopped after the grinding wheel runs for 30,000 revolutions or the coating wears through (whichever comes first). Record the reduction in thickness and weight of the powder coating or solvent-based coating, accurate to 1 μm for thickness and 0.001 g for weight. If the coating does not wear through after 30,000 revolutions, record the thickness and weight wear after 30,000 revolutions. If the coating wears through after 6,000 revolutions, record the thickness and weight wear after 6,000 revolutions. "Wearing through" here refers to exposing the anti-corrosion layer (if an anti-corrosion layer exists) or the metal plate (if no anti-corrosion layer exists). Since the above wear test simulates the actual situation of a battery swapping station, if the powder coating on the bottom plate does not wear through after 30,000 revolutions, it can be approximately assumed that the battery pack containing this bottom plate will not have its powder coating worn through after 1500 cycles at the battery swapping station, equivalent to an increased battery pack lifespan of 15 years.

[0071] 7. Slippage Test

[0072] The battery pack bottom protection plates of each embodiment and comparative example were cut into 100mm × 100mm rectangular specimens. The sliding friction and slippage of the coating were tested using an abrasion tester at room temperature (23℃ ± 2℃) and relative humidity (50% ± 5%). The test conditions and the grinding wheel used were consistent with those described in the Taber test section.

[0073] Since battery packs with powder-coated bottom plates are more prone to sliding friction and slippage at the polyurethane rollers compared to the nitrile rubber chain cover, a polyurethane grinding wheel was used to simulate the polyurethane rollers at NIO's battery swapping station to test the sliding friction and slippage of the bottom plate.

[0074] If no idling of the polyurethane grinding wheel is observed during its 30,000 revolutions, and there are no abnormal noises or problems with the positioning of the bottom guard plate, then it can be assumed that there is no slippage or friction. It can also be approximated that the battery pack with this bottom guard plate will not experience slippage or friction at the nitrile rubber chain cover and polyurethane roller during actual operation at the battery swapping station.

[0075] Example 1

[0076] The battery pack bottom protector of this embodiment includes a metal plate serving as the base and a powder coating on the surface of the metal plate. An anti-corrosion layer is also provided between the powder coating and the metal plate. The metal plate is made of steel, the anti-corrosion layer is an epoxy primer layer, and the powder coating is a polyester powder coating. The thickness of the anti-corrosion layer, the thickness of the powder coating, the Shore hardness D, the surface roughness, and the static and dynamic coefficients of friction with nitrile rubber are detailed in Table 1. The overall thickness of the battery pack bottom protector is 0.8 mm to 1 mm.

[0077] In the preparation of the battery pack bottom protector, an epoxy primer is first sprayed onto the surface of a steel plate. After baking, the bottom protector substrate is obtained, which is a steel plate covered with epoxy primer. The dry film thickness of the epoxy primer layer is 53 μm. The back of the bottom protector substrate is masked with masking tape. Polyester powder coating is sprayed onto the front of the bottom protector substrate. After drying, the masking tape on the back is removed to obtain the battery pack bottom protector. The thickness of the polyester powder coating is 257 μm, the Shore hardness D is 84.4, the surface roughness Sa is 20.2 μm, the static friction coefficient with nitrile rubber is 0.78, and the dynamic friction coefficient with nitrile rubber is 0.70.

[0078] Example 2

[0079] The battery pack bottom protector of this embodiment includes a metal plate serving as the base and a powder coating applied to the surface of the metal plate. The metal plate is made of steel, and the powder coating is an epoxy powder coating. Details of the powder coating thickness, Shore hardness D, surface roughness, static friction coefficient with nitrile rubber, and dynamic friction coefficient are shown in Table 1. The overall thickness of the battery pack bottom protector is 0.8 mm to 1 mm.

[0080] In the preparation of the battery pack bottom protector, the back of the steel plate is first masked with masking tape, and then an epoxy powder coating is sprayed onto the surface of the steel plate. After drying, the masking tape is removed to obtain the battery pack bottom protector. The epoxy powder coating has a thickness of 138 μm, a Shore hardness D of 72.8, a surface roughness Sa of 46.3 μm, a static friction coefficient with nitrile rubber of 0.66, and a dynamic friction coefficient with nitrile rubber of 0.65.

[0081] Example 3

[0082] The battery pack bottom protector in Example 3 was developed based on Example 2 by changing the spraying process parameters or adding 0.1wt%-5wt% of a texture additive to the powder coating to adjust the thickness, Shore hardness D, surface roughness, static friction coefficient, and dynamic friction coefficient with nitrile rubber. Specific adjustment data are shown in Table 1.

[0083] Example 4

[0084] The battery pack bottom protector in Example 4 was developed based on Example 2 by changing the spraying process parameters or adding 0.1wt%-5wt% of silicone additives to the powder coating to adjust the thickness, Shore hardness D, surface roughness, and static and dynamic coefficients of friction with nitrile rubber. Specific adjustment data are shown in Table 1.

[0085] Example 5

[0086] The battery pack bottom protector of this embodiment includes a metal plate serving as the base and a powder coating on the surface of the metal plate, with an anti-corrosion layer between the powder coating and the metal plate. The metal plate is made of steel, the anti-corrosion layer is an epoxy electrophoretic paint layer, and the powder coating is a polyamide (PA11) powder coating. Details of the thickness of the anti-corrosion layer, the thickness of the powder coating, the Shore hardness D, the surface roughness, and the static and dynamic coefficients of friction with nitrile rubber are shown in Table 1. The overall thickness of the battery pack bottom protector is 0.8 mm-1 mm.

[0087] In the preparation of the battery pack bottom protector, epoxy is first electrophoretically applied to the surface of a steel plate. After baking, the bottom protector substrate is obtained, which is a steel plate with an epoxy electrophoretic coating. The dry film thickness of the epoxy electrophoretic coating layer is 31 μm. The back of the bottom protector substrate is masked with masking tape, and polyamide (PA11) powder coating is sprayed onto the front of the bottom protector substrate. After drying, the masking tape on the back is removed to obtain the battery pack bottom protector. The epoxy powder coating has a thickness of 120 μm, a Shore hardness D of 94.7, a surface roughness Sa of 46.7 μm, a static friction coefficient with nitrile rubber of 0.73, and a dynamic friction coefficient with nitrile rubber of 0.65.

[0088] Comparative Example 1

[0089] The battery pack bottom protector of this comparative example includes a metal plate serving as the base and a solvent-based coating applied to the surface of the metal plate. An anti-corrosion layer is also provided between the solvent-based coating and the metal plate. The metal plate is made of steel, the anti-corrosion layer is an epoxy electrophoretic paint layer, and the solvent-based coating is a polyvinyl chloride (PVC) coating. The thickness of the anti-corrosion layer, the thickness of the solvent-based coating, the Shore hardness D, the surface roughness, and the static and dynamic coefficients of friction with nitrile rubber are detailed in Table 1. The overall thickness of the battery pack bottom protector is 0.8 mm–1 mm.

[0090] In the preparation of the battery pack bottom protector, epoxy resin is first electrophoretically applied to the surface of a steel plate. After baking, the bottom protector substrate is obtained, which is a steel plate coated with epoxy electrophoretic paint. The dry film thickness of the epoxy electrophoretic paint layer is 28 μm. The back of the bottom protector substrate is masked with masking tape. A PVC solvent-based coating is sprayed onto the front of the bottom protector substrate. After drying, the masking tape on the back is removed to obtain the battery pack bottom protector. The thickness of the PVC solvent-based coating is 995 μm, the Shore hardness D is 56.2, the surface roughness Sa is 56.4 μm, the static friction coefficient with nitrile rubber is 0.84, and the dynamic friction coefficient with nitrile rubber is 0.75.

[0091] Comparative Example 2

[0092] The battery pack bottom protector in Comparative Example 2 was developed based on Comparative Example 1 by adjusting the spraying process parameters to modify the thickness, Shore hardness D, surface roughness, static friction coefficient, and dynamic friction coefficient with nitrile rubber of the PVC solvent-based coating. Specific adjustment data are shown in Table 1.

[0093] Comparative Example 3

[0094] The battery pack bottom protector of this comparative example includes a metal plate serving as the base and a powder coating on the surface of the metal plate, with an anti-corrosion layer between the powder coating and the metal plate. The metal plate is made of steel, the anti-corrosion layer is an epoxy electrophoretic paint layer, and the powder coating is a PA11 powder coating. The thickness of the anti-corrosion layer, the thickness of the powder coating, the Shore hardness D, the surface roughness, and the static and dynamic coefficients of friction with nitrile rubber are detailed in Table 1. The overall thickness of the battery pack bottom protector is 0.8 mm–1 mm.

[0095] In the preparation of the battery pack bottom protector, epoxy resin is first electrophoretically applied to the surface of a steel plate. After baking, the bottom protector substrate is obtained, which is a steel plate coated with epoxy electrophoretic paint. The dry film thickness of the epoxy electrophoretic paint is 24 μm. The back of the bottom protector substrate is masked with masking tape, and PA11 powder coating is sprayed onto the front of the bottom protector substrate. After drying, the masking tape on the back is removed to obtain the battery pack bottom protector. The thickness of the PA11 powder coating is 82 μm, the Shore hardness D is 90.9, the surface roughness Sa is 16.2 μm, the static friction coefficient with nitrile rubber is 0.42, and the dynamic friction coefficient with nitrile rubber is 0.32.

[0096] Comparative Example 4

[0097] The battery pack bottom protector in Comparative Example 4 was developed based on Comparative Example 1. The thickness of the anti-corrosion layer was adjusted by changing the electrophoresis process parameters, and the thickness, Shore hardness D, surface roughness, static friction coefficient, and dynamic friction coefficient with nitrile rubber were adjusted by changing the spraying process parameters. Specific adjustment data are shown in Table 1.

[0098] Comparative Example 5

[0099] The battery pack bottom protector in Comparative Example 5 was developed based on Comparative Example 1. The thickness of the anti-corrosion layer was adjusted by changing the electrophoresis process parameters. The thickness, Shore hardness D, surface roughness, and static and dynamic friction coefficients with nitrile rubber of the PA11 powder coating were adjusted by changing the spraying process parameters or by adding 5wt%-8wt% inorganic particulate powder to the powder coating. Specific adjustment data are shown in Table 1.

[0100] Comparative Example 6

[0101] The battery pack bottom protector of this comparative example includes a metal plate serving as the base and a powder coating applied to the surface of the metal plate. The metal plate is made of steel, and the powder coating is an epoxy powder coating. Details of the powder coating thickness, Shore hardness D, surface roughness, static friction coefficient with nitrile rubber, and dynamic friction coefficient are shown in Table 1. The overall thickness of the battery pack bottom protector is 0.8 mm–1 mm.

[0102] In the preparation of the battery pack bottom protector, the back of the steel plate is first masked with masking tape, and then epoxy powder coating is sprayed onto the surface of the steel plate. After drying, the masking tape is removed to obtain the battery pack bottom protector. The epoxy powder coating has a thickness of 130 μm, a Shore hardness D of 91.8, a surface roughness Sa of 17.5 μm, a static friction coefficient with nitrile rubber of 0.45, and a dynamic friction coefficient with nitrile rubber of 0.40.

[0103] Comparative Example 7

[0104] The battery pack bottom protector of Comparative Example 7 was developed based on Comparative Example 6 by changing the spraying process parameters or adding 0.5wt%-3wt% of foaming agent to the powder coating to adjust the thickness, Shore hardness D, surface roughness, static friction coefficient, and dynamic friction coefficient with nitrile rubber. Specific adjustment data are shown in Table 1.

[0105] Comparative Example 8

[0106] The battery pack bottom protector of Comparative Example 8 was developed based on Comparative Example 6 by changing the spraying process parameters or adding 0.5wt%-3wt% of foaming agent to the powder coating to adjust the thickness, Shore hardness D, surface roughness, static friction coefficient, and dynamic friction coefficient with nitrile rubber. Specific adjustment data are shown in Table 1.

[0107] Comparative Example 9

[0108] The battery pack bottom protector of Comparative Example 9 was developed based on Comparative Example 6 by changing the spraying process parameters to adjust the thickness of the epoxy powder coating, Shore hardness D, surface roughness, and the static and dynamic coefficients of friction with nitrile rubber. Specific adjustment data are shown in Table 1.

[0109] Table 1

[0110] Table 2 records the rotational wear test results of the bottom plates of each embodiment and comparative example at 30,000 rpm, as well as the results of whether slippage occurred during the test. It can be seen that, compared with the bottom plates of comparative examples 1-9, the bottom plates of embodiments 1-6 of this application do not exhibit sliding friction slippage with the polyurethane grinding wheel during the entire rotational wear test at 30,000 rpm. They also demonstrate excellent wear resistance, indicating that in actual operation at the battery swapping station, they can not only increase the number of battery pack cycles and improve battery pack lifespan, but also prevent sliding friction slippage at the polyurethane roller and nitrile rubber chain cover. Furthermore, the powder coating of the bottom plates of embodiments 1-6 of this application can withstand 10 g / mm². 2 -20g / mm 2 It can withstand pressure without causing the coating to crack, break, or peel.

[0111] Table 2

[0112] While some exemplary embodiments of this application have been described and illustrated, this application is not limited to the disclosed embodiments. Rather, those skilled in the art will recognize that modifications and changes may be made to the described embodiments without departing from the spirit and scope of this application as described in the appended claims.

Claims

1. A battery pack underpan, characterized by, The metal plate and the powder coating layer arranged on the surface of the metal plate, the thickness of the powder coating layer is 50-400 microns, the surface roughness of the powder coating layer is 15-60 microns, the dynamic friction coefficient of the powder coating layer and the nitrile rubber is greater than or equal to 0.

5.

2. The battery pack skid plate of claim 1, wherein, The dynamic friction coefficient of the powder coating layer and the nitrile rubber is 0.5-0.

95.

3. The battery pack underpan of claim 1 or 2, wherein, The static friction coefficient of the powder coating layer and the nitrile rubber is 0.6-0.

98.

4. The battery pack underguard of claim 1 or 2, wherein, The powder coating of the powder coating layer is selected from polyester powder coating, epoxy powder coating and polyamide powder coating.

5. The battery pack underguard of claim 1 or 2, wherein, The Shore D hardness of the powder coating layer is 50-95.

6. The battery pack skid plate of claim 1 or 2, wherein, The metal plate and the powder coating layer are further provided with a corrosion protection layer, and the thickness of the corrosion protection layer is 20-60 microns.

7. The battery pack skid plate of claim 6, wherein, The corrosion protection layer is an epoxy primer layer or an epoxy electrophoretic paint layer.

8. A battery pack, characterized by, The battery pack bottom guard plate according to any one of claims 1-7, wherein the powder coating layer is arranged on the outer surface of the battery pack.

9. The battery pack of claim 8, wherein, The powder coating has a pressure of 10 g / mm 2 - 20 g / mm 2 .

10. A vehicle characterized by comprising: The battery pack according to claim 8 or 9, wherein the battery pack is installed in the vehicle.

11. The vehicle of claim 10, wherein, The vehicle has a structure for replacing the battery pack.

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