Automobile power battery water-cooling plate, manufacturing method thereof, battery and vehicle

Abstract

The application belongs to the technical field of electric vehicle batteries, and discloses a water cooling plate for a vehicle power battery, a manufacturing method of the water cooling plate, a battery and a vehicle, which comprises an upper plate and a lower plate, the material of the upper plate is a pure copper plate or an oxygen-free copper plate, the lower plate comprises a high-strength steel plate with a tensile strength greater than 780 MPa and a copper-zinc alloy plating layer, the high-strength steel plate is provided with a groove, the upper surface of the high-strength steel plate is electroplated with the copper-zinc alloy plating layer, the lower bottom surface of the upper plate is attached to the copper-zinc alloy plating layer and is welded, sealed and fixed, and the upper plate covers the groove of the high-strength steel plate to form a cooling circulating water channel. The design of the application can efficiently transfer the heat generated by the battery to the cooling liquid, significantly improve the battery charging and discharging performance, and prevent thermal runaway. The lower plate does not produce cracks or tearing failure under the condition of supporting the battery pack, prevents the leakage of the cooling liquid and the occurrence of short-circuit fire accidents, has high brazing strength of the copper-steel upper and lower plates, has a longer service life, does not need to additionally increase a bottom protection plate, is beneficial to the lightweight of the battery pack, and improves the cruising range of the vehicle.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle battery technology, specifically relating to a water-cooled plate for an automotive power battery and its manufacturing method, as well as the battery and vehicle. Background Technology

[0002] Automotive power battery water-cooling plates control battery temperature through internally circulating coolant. In high-temperature environments, they quickly remove the large amount of heat generated during battery charging and discharging, preventing battery performance degradation or thermal runaway. In low-temperature environments, the internally circulating warm coolant heats the battery, ensuring battery activity and charging capacity. At the same time, the water-cooling plate system also ensures that the temperature of all cells in the battery pack is uniform, avoiding local overheating or overcooling and improving battery performance.

[0003] The existing structure and manufacturing process of power battery water-cooled plates are as follows: the water-cooled plate is divided into an upper plate and a lower plate. The upper plate is in contact with the battery module, and the lower plate is in contact with the lower housing of the battery pack. Cooling water channels are set between the upper and lower plates to remove battery heat by the flow of coolant. Both the upper and lower plates are made of aluminum plate material through a stamping process. The commonly used aluminum plate grade is 3003 aluminum alloy. After the upper and lower plates are made into individual pieces through the stamping process, they are then made into a water-cooled plate assembly by aluminum brazing. The water-cooled plate assembly is then fixed to the battery pack by screwing. Currently, the application of aluminum alloy water-cooled plates faces two main challenges. First, the thermal conductivity of aluminum alloy is insufficient, which cannot efficiently transfer the heat generated by the battery to the coolant, easily leading to excessively high battery temperatures, affecting battery performance or causing thermal runaway. Second, aluminum alloy has low strength and plasticity, making the water-cooled plate prone to tearing under battery pack support conditions, resulting in coolant leakage and potentially causing short circuits and fires in the battery pack. Currently, the common approach is to add a steel bottom plate to protect the water-cooled plate under battery pack support conditions, but this method complicates the battery pack structure and increases weight and cost.

[0004] In summary, existing power battery water-cooling plates still have significant shortcomings in structural design, material selection, and manufacturing processes. Problems such as low thermal conductivity, poor impact resistance, and unreasonable protection schemes make it difficult to fully meet the requirements of power batteries for thermal management accuracy, structural reliability, and cost control. Therefore, developing a power battery water-cooling plate that can solve the above-mentioned technical pain points has become an urgent technical problem to be solved in the field of thermal management of new energy vehicles. Summary of the Invention

[0005] The purpose of this invention is to provide a water-cooled plate for automotive power batteries, its manufacturing method, battery, and vehicle. The upper plate of the battery water-cooled plate is made of pure copper or oxygen-free copper plate by stamping, while the lower plate is made of high-strength steel plate with grooves, electroplated with a special copper-zinc alloy coating and stamped. The copper-zinc coating serves as the brazing filler layer connecting the high-strength steel plate and the upper plate, sealing and fixing the copper upper plate and the steel lower plate together to form a water-cooled plate assembly. This assembly efficiently transfers heat generated by the battery to the coolant, significantly improving battery charging and discharging performance and preventing thermal runaway. The high-strength steel lower plate maintains structural stability even under battery pack bottom conditions, preventing cracks or tearing failures and preventing coolant leakage and short-circuit fires. The brazing strength of the copper upper plate and steel lower plate is significantly higher than that of aluminum alloy plates, remaining effective even under extreme durability conditions, preventing coolant leakage, and extending service life. Therefore, no additional bottom protection plate is needed, which is beneficial for battery pack weight reduction and improving vehicle range.

[0006] The specific details of the plan are as follows:

[0007] A water-cooled plate for an automotive power battery includes an upper plate and a lower plate. The upper plate is made of pure copper or oxygen-free copper. The lower plate includes a high-strength steel plate and a copper-zinc alloy coating. The high-strength steel plate has a tensile strength greater than 780 MPa. The high-strength steel plate has grooves. The upper surface of the high-strength steel plate is electroplated with a copper-zinc alloy coating. The lower bottom surface of the upper plate is attached to the copper-zinc alloy coating and welded and sealed. The upper plate covers the grooves of the high-strength steel plate to form a cooling circulation channel.

[0008] Furthermore, the composition of the copper-zinc alloy coating, by mass percentage, includes Cu 58%~60%, Zn 36%~38%, Sn 0.5%~0.8%, Si 0.1%~0.2%, Mn 0.8%~1.0%, Fe 0.2%~0.5%, Cr 1.2%~1.5%, and Ni 0.1%~0.4%.

[0009] Furthermore, the thickness of the lower plate is 2.0mm~3.0mm, of which the thickness of the copper-zinc alloy plating layer accounts for 8%~15% of the total thickness of the lower plate.

[0010] Furthermore, a copper-zinc alloy coating is uniformly electroplated on one side of the upper surface of the high-strength steel plate. The copper-zinc alloy coating serves as a brazing filler metal, and the upper plate is brazed and sealed to the lower plate through the copper-zinc alloy coating.

[0011] A method for manufacturing the aforementioned automotive power battery water-cooling plate includes the following steps:

[0012] S1. Select a pure copper plate or oxygen-free copper plate of preset thickness, process it into shape by stamping according to the product design structure, and obtain the upper plate.

[0013] S2. Select a high-strength steel plate of a preset thickness as the substrate of the lower plate. Through a preset electroplating process, uniformly electroplat a copper-zinc alloy coating on one side of the upper surface of the high-strength steel plate. Then, according to the product design structure, the high-strength steel plate with the copper-zinc alloy coating is stamped into the lower plate.

[0014] S3. Fit the upper plate and the lower plate together, and use the copper-zinc alloy plating on the upper surface of the high-strength steel plate as the brazing filler metal to braze the upper plate and the lower plate. The gap value of all brazing mating surfaces of the upper plate and the lower plate is ≤0.3mm, so that the upper and lower plates are connected as one piece by brazing and sealing to obtain the water-cooled plate assembly.

[0015] Furthermore, in step S2, the plating solution used for electroplating high-strength steel plates has a copper ion concentration of 8~15 g / L, a zinc ion concentration of 5~10 g / L, a manganese ion concentration of 0.1~0.5 g / L, and a trivalent chromium ion concentration of 0.3~1.0 g / L.

[0016] Furthermore, in step S2, during the electroplating of high-strength steel plates, the temperature range is 40℃~50℃, the pH value of the plating solution ranges from 8.0 to 9.0, the cathode current density ranges from 2.0 to 3.0 A / dm2, and the electroplating time ranges from 1.5 to 2.0 h.

[0017] Furthermore, in step S3, when brazing the upper and lower plates, an in-furnace brazing method is used, with a brazing temperature of 920℃~950℃ and a brazing time of 6min~10min.

[0018] A battery, including the aforementioned automotive power battery water-cooling plate.

[0019] A vehicle comprising the battery described above.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. This invention utilizes the significantly higher thermal conductivity of pure copper or oxygen-free copper plates compared to aluminum alloys to efficiently transfer the heat generated by the battery to the coolant via the upper copper plate, maintaining the battery temperature balance and stability with high quality, significantly improving battery charge and discharge performance, and preventing thermal runaway.

[0022] 2. This invention utilizes the high strength and high plasticity of steel plates to ensure the stability of the water-cooled plate structure under the condition of supporting the battery pack, preventing the lower plate from cracking or tearing and thus preventing coolant leakage and short-circuit fire accidents.

[0023] 3. The copper-zinc alloy plating on the surface of the lower plate of the present invention uses a special composition, which satisfies both the electroplating performance of the steel plate surface and the brazing performance of dissimilar materials such as steel and copper;

[0024] 4. The brazing strength of the copper-steel composite water-cooled plate of the present invention is significantly higher than that of the aluminum alloy plate. Under extreme durability conditions, it will not cause the brazing connection of the water-cooled plate to fail or the coolant to leak. Therefore, the copper-steel composite water-cooled plate assembly has a longer service life.

[0025] 5. The copper-steel composite water-cooled plate of the present invention has high structural strength and good rigidity performance, and does not require an additional bottom guard plate for protection. Therefore, the application of copper-steel composite water-cooled plate is beneficial to the weight reduction of the battery pack assembly, thereby increasing the energy density of the battery pack and improving the driving range of the vehicle. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the water-cooled plate for automotive power batteries according to the present invention.

[0027] Figure 2 This is a partial structural schematic diagram of the water-cooled plate for automotive power batteries according to the present invention.

[0028] Figure 3 This is a schematic diagram of the upper and lower plates of the automotive power battery water cooling plate of the present invention.

[0029] Figure 4 This is a schematic diagram of the vertical cross-section of the water-cooled plate for an automotive power battery according to the present invention.

[0030] In the picture:

[0031] 1. Upper plate; 2. Lower plate; 2.1 High-strength steel plate; 2.2 Copper-zinc alloy coating; 2.3 Groove; 3. Brazed weld. Detailed Implementation

[0032] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0035] The following combination Figures 1-4 The embodiments are described in detail below:

[0036] This invention provides a water-cooled plate for automotive power batteries, see Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, it includes an upper plate 1 and a lower plate 2. The upper plate 1 is made of pure copper plate or oxygen-free copper plate. The lower plate 2 includes a high-strength steel plate 2.1 and a copper-zinc alloy plating layer 2.2. The tensile strength of the high-strength steel plate 2.1 is greater than 780MPa. The high-strength steel plate 2.1 has a groove 2.3. The upper surface of the high-strength steel plate 2.1 is electroplated with a copper-zinc alloy plating layer 2.2. The lower bottom surface of the upper plate 1 is attached to the copper-zinc alloy plating layer 2.2 and welded and sealed. The upper plate 1 covers the groove 2.3 of the high-strength steel plate 2.1 to form a cooling circulation channel.

[0037] The composition of the copper-zinc alloy coating 2.2, by mass percentage, includes Cu 58%~60%, Zn 36%~38%, Sn 0.5%~0.8%, Si 0.1%~0.2%, Mn 0.8%~1.0%, Fe 0.2%~0.5%, Cr 1.2%~1.5%, and Ni 0.1%~0.4%.

[0038] The thickness of the lower plate 2 is 2.0mm~3.0mm, of which the thickness of the copper-zinc alloy plating layer 2.2 accounts for 8%~15% of the total thickness of the lower plate 2.

[0039] A copper-zinc alloy plating layer 2.2 is uniformly electroplated on one side of the upper surface of the high-strength steel plate 2.1. The copper-zinc alloy plating layer 2.2 serves as a brazing filler metal, and the upper plate 1 is brazed and sealed to the lower plate 2 through the copper-zinc alloy plating layer 2.2.

[0040] The present invention also provides a method for manufacturing the aforementioned automotive power battery water-cooling plate, the steps of which include:

[0041] S1. Select a pure copper plate or oxygen-free copper plate of preset thickness, process it into shape by stamping according to the product design structure, and obtain the upper plate 1.

[0042] S2. Select a high-strength steel plate 2.1 of a preset thickness as the base material of the lower plate 2. Use a preset electroplating process to uniformly electroplat a copper-zinc alloy coating 2.2 on one side of the upper surface of the high-strength steel plate 2.1. Then, according to the product design structure, the high-strength steel plate 2.1 with the copper-zinc alloy coating 2.2 is stamped into the lower plate 2.

[0043] S3. Fit the upper plate 1 and the lower plate 2 together. Use the copper-zinc alloy plating layer 2.2 on the upper surface of the high-strength steel plate 2.1 as the brazing filler metal to braze the upper plate 1 and the lower plate 2. The gap value of all brazing mating surfaces of the upper plate 1 and the lower plate 2 is ≤0.3mm, so that the upper and lower plates 2 are connected as one piece by brazing and sealing to obtain the water-cooled plate assembly.

[0044] In step S2, the plating solution used for electroplating the high-strength steel plate 2.1 has a copper ion concentration of 8~15g / L, a zinc ion concentration of 5~10g / L, a manganese ion concentration of 0.1~0.5g / L, and a trivalent chromium ion concentration of 0.3~1.0g / L.

[0045] In step S2, when electroplating the high-strength steel plate 2.1, the temperature range is 40℃~50℃, the pH value of the plating solution ranges from 8.0 to 9.0, the cathode current density ranges from 2.0 to 3.0 A / dm2, and the electroplating time ranges from 1.5 to 2.0 h.

[0046] In step S3, when brazing the upper plate 1 and the lower plate 2, the furnace brazing method is used, the brazing temperature is 920℃~950℃, and the brazing time is 6min~10min.

[0047] The present invention also provides a battery, including the aforementioned automotive power battery water cooling plate.

[0048] The present invention also provides a vehicle including the battery described above.

[0049] Example 1:

[0050] The water-cooled plate for the automotive power battery in this embodiment has the following structure and materials: The water-cooled plate assembly includes an upper plate and a lower plate. A cooling circulation channel is set between the upper and lower plates according to factors such as cooling and heat dissipation requirements and cooling water flow rate. The upper and lower plates are connected and sealed by copper brazing. The upper plate is made of T2 pure copper plate with a thickness of 1.4mm. The lower plate is made of high-strength steel plate with a tensile strength of 860MPa. The surface of the high-strength steel plate is electroplated with a copper-zinc alloy coating. The total thickness of the coated steel plate is 2.5mm, of which the coating thickness accounts for 10% of the total thickness of the lower plate.

[0051] The composition of the copper-zinc alloy coating by mass percentage is: Cu 58.5%, Zn 37.0%, Sn 0.6%, Si 0.1%, Mn 1.0%, Fe 0.4%, Cr 1.4%, Ni 0.3%, with the remainder being impurity elements;

[0052] The lower steel plate is electroplated only on the upper surface that contacts the upper copper plate. After electroplating, five points are randomly selected for coating thickness testing, and the coating thicknesses are 0.24mm, 0.25mm, 0.24mm, 0.25mm, and 0.25mm, respectively.

[0053] The manufacturing process of the automotive power battery water-cooling plate is as follows: First, a 1.4mm thick T2 pure copper plate is stamped into an upper plate according to the product design structure; second, a copper-zinc alloy coating is electroplated onto the upper surface of a lower high-strength steel plate using an electroplating process, and then the coated steel plate is stamped into a lower plate according to the product design structure; finally, the coating on the upper surface of the lower plate is used as a brazing filler metal to braze the upper and lower plates together to form an integrated water-cooling plate assembly.

[0054] The upper and lower plates are assembled after stamping, and the clearance value of all brazed mating surfaces of the parts is 0.16mm-0.22mm;

[0055] When electroplating the lower layer of high-strength steel plate, the concentration of copper ions in the plating solution is 12.0 g / L, the concentration of zinc ions is 8.0 g / L, the concentration of manganese ions is 0.3 g / L, and the concentration of trivalent chromium ions is 0.6 g / L. The content of other elements is added according to the composition ratio of the alloy coating.

[0056] When electroplating the lower high-strength steel plate, the electroplating temperature is 45℃, the pH value of the plating solution is 8.5, the cathode current density is 2.5A / dm2, and the electroplating time is 1.8h.

[0057] Before brazing the upper and lower plates, wipe the surface of the parts with acetone to remove oil, impurities, electroplating solution and other contaminants.

[0058] When brazing the upper and lower plates, the furnace brazing method is used, the brazing temperature is 935℃, and the brazing time is 8 minutes.

[0059] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld 3 is 2.0%, and the tensile shear strength of the brazed weld 3 is 379 MPa. Under the condition of the battery pack being supported, the water-cooled plate and the brazed weld do not produce cracks or tears. Simulation analysis shows that under normal battery operating conditions, the maximum battery temperature is 36.2℃. All of the above meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and no cracks or tears in the water-cooled plate and the brazed weld under the condition of the battery pack being supported. Simulation analysis shows that the battery product performance design requirements are ≤36.5℃ under normal battery operating conditions.

[0060] Example 2:

[0061] The water-cooled plate for the automotive power battery in this embodiment has the following structure and materials: The water-cooled plate assembly includes an upper plate and a lower plate. A cooling circulation channel is set between the upper and lower plates according to factors such as cooling and heat dissipation requirements and cooling water flow rate. The upper and lower plates are connected and sealed by copper brazing. The upper plate is made of TU2 oxygen-free copper plate with a thickness of 1.2mm. The lower plate is made of high-strength steel plate with a tensile strength of 1080MPa. The surface of the high-strength steel plate is electroplated with a copper-zinc alloy coating. The total thickness of the steel plate with the coating is 2.2mm, of which the coating thickness accounts for 9% of the total thickness of the lower plate.

[0062] The composition of the copper-zinc alloy coating, by mass percentage, is: Cu 59.5%, Zn 36.0%, Sn 0.7%, Si 0.1%, Mn 0.8%, Fe 0.3%, Cr 1.5%, Ni 0.3%, with the remainder being impurity elements;

[0063] The lower steel plate is electroplated only on the upper surface that contacts the upper copper plate. After electroplating, five points are randomly selected for coating thickness testing. The coating thicknesses are 0.20mm, 0.19mm, 0.20mm, 0.20mm, and 0.21mm, respectively.

[0064] The manufacturing process of the automotive power battery water-cooling plate is as follows: First, a 1.2mm thick TU2 oxygen-free copper plate is stamped into an upper plate according to the product design structure; second, a copper-zinc alloy coating is electroplated onto the upper surface of a lower high-strength steel plate, and then the coated steel plate is stamped into a lower plate according to the product design structure; finally, the coating on the upper surface of the lower plate is used as a brazing filler to braze the upper and lower plates together to form an integrated water-cooling plate assembly.

[0065] In the above scheme, the upper plate and the lower plate are assembled after stamping, and the gap value of all brazed mating surfaces of the parts is 0.15mm-0.28mm;

[0066] When electroplating the lower layer of high-strength steel plate, the concentration of copper ions in the plating solution is 11.0 g / L, the concentration of zinc ions is 7.5 g / L, the concentration of manganese ions is 0.2 g / L, and the concentration of trivalent chromium ions is 0.5 g / L. The content of other elements is added according to the composition ratio of the alloy coating.

[0067] When electroplating the lower high-strength steel plate, the electroplating temperature is 50℃, the pH value of the plating solution is 9.0, the cathode current density is 2.8A / dm2, and the electroplating time is 1.6h.

[0068] Before brazing the upper and lower plates, wipe the surface of the parts with alcohol to remove oil, impurities, electroplating solution and other contaminants.

[0069] When brazing the upper and lower plates, the furnace brazing method is used, the brazing temperature is 945℃, and the brazing time is 7 minutes.

[0070] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 2.3%, and the tensile shear strength of the brazed weld was 362 MPa. Under the condition of the battery pack being supported at the bottom, the water-cooled plate and the brazed weld did not produce cracks or tears. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 34.8℃. All of the above meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and no cracks or tears in the water-cooled plate and the brazed weld under the condition of the battery pack being supported at the bottom. Simulation analysis also showed that the battery product performance design requirements of a maximum temperature ≤36.5℃ under normal battery operating conditions were met.

[0071] Example 3:

[0072] The water-cooled plate for the automotive power battery in this embodiment has the following structure and materials: The water-cooled plate assembly includes an upper plate and a lower plate. A cooling circulation channel is set between the upper and lower plates according to factors such as cooling and heat dissipation requirements and cooling water flow rate. The upper and lower plates are connected and sealed by copper brazing. The upper plate is made of T2 pure copper plate with a thickness of 1.0 mm. The lower plate is made of high-strength steel plate with a tensile strength of 1180 MPa. The surface of the high-strength steel plate is electroplated with a copper-zinc alloy coating. The total thickness of the steel plate with the coating is 2.0 mm, of which the coating thickness accounts for 8% of the total thickness of the lower plate.

[0073] In the above scheme, the composition of the copper-zinc alloy coating, by mass percentage, is Cu 60.0%, Zn 36.0%, Sn 0.6%, Si 0.2%, Mn 0.8%, Fe 0.5%, Cr 1.2%, Ni 0.2%, with the others being impurity elements;

[0074] The lower steel plate is electroplated only on the upper surface that contacts the upper copper plate. After electroplating, five points are randomly selected for plating thickness testing. The plating thicknesses are 0.16mm, 0.16mm, 0.15mm, 0.15mm, and 0.16mm, respectively.

[0075] The manufacturing process of this automotive power battery water-cooling plate is as follows: First, a 1.0mm thick T2 pure copper plate is stamped into an upper plate according to the product design structure; second, a copper-zinc alloy coating is electroplated onto the upper surface of a lower high-strength steel plate, and then the coated steel plate is stamped into a lower plate according to the product design structure; finally, the coating on the upper surface of the lower plate is used as a brazing filler metal to braze the upper and lower plates together to form an integrated water-cooling plate assembly.

[0076] The upper and lower plates are assembled after stamping, and the clearance value of all brazed mating surfaces of the parts is 0.15mm-0.23mm;

[0077] When electroplating the lower layer of high-strength steel plate, the concentration of copper ions in the plating solution is 13.0 g / L, the concentration of zinc ions is 10.0 g / L, the concentration of manganese ions is 0.4 g / L, and the concentration of trivalent chromium ions is 0.3 g / L. The content of other elements is added according to the composition ratio of the alloy coating.

[0078] When electroplating the lower high-strength steel plate, the electroplating temperature is 50℃, the pH value of the plating solution is 8.5, the cathode current density is 2.2A / dm2, and the electroplating time is 1.9h.

[0079] Before brazing the upper and lower plates, wipe the surface of the parts with acetone to remove oil, impurities, electroplating solution and other contaminants.

[0080] When brazing the upper and lower plates, the furnace brazing method is used, the brazing temperature is 950℃, and the brazing time is 6 minutes.

[0081] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 3.2%, and the tensile shear strength of the brazed weld was 338 MPa. Under the condition of the battery pack being supported, the water-cooled plate and the brazed weld did not produce cracks or tears. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 35.9℃. All of the above meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and no cracks or tears in the water-cooled plate and the brazed weld under the condition of the battery pack being supported. Simulation analysis also showed that the battery product performance design requirements of a maximum temperature ≤36.5℃ under normal battery operating conditions were met.

[0082] Example 4:

[0083] The water-cooled plate for the automotive power battery in this embodiment has the following structure and materials: The water-cooled plate assembly includes an upper plate and a lower plate. A cooling circulation channel is set between the upper and lower plates according to factors such as cooling and heat dissipation requirements and cooling water flow rate. The upper and lower plates are connected and sealed by copper brazing. The upper plate is made of T2 pure copper plate with a thickness of 1.4mm. The lower plate is made of high-strength steel plate with a tensile strength of 860MPa. The surface of the high-strength steel plate is electroplated with a copper-zinc alloy coating. The total thickness of the steel plate with the coating is 2.5mm, of which the coating thickness accounts for 10% of the total thickness of the lower plate.

[0084] The composition of the copper-zinc alloy coating, by mass percentage, is Cu 58.0%, Zn 38.0%, Sn 0.5%, Si 0.1%, Mn 0.8%, Fe 0.2%, Cr 1.5%, Ni 0.4%, with the remainder being impurity elements;

[0085] The lower steel plate is electroplated only on the upper surface that contacts the upper copper plate. After electroplating, five points are randomly selected for coating thickness testing. The coating thicknesses are 0.25mm, 0.25mm, 0.25mm, 0.24mm, and 0.25mm, respectively.

[0086] The manufacturing process of this automotive power battery water-cooling plate is as follows: First, a 1.4mm thick T2 pure copper plate is stamped into an upper plate according to the product design structure; second, a copper-zinc alloy coating is electroplated onto the upper surface of a lower high-strength steel plate, and then the coated steel plate is stamped into a lower plate according to the product design structure; finally, the coating on the upper surface of the lower plate is used as a brazing filler metal to braze the upper and lower plates together to form an integrated water-cooling plate assembly.

[0087] The upper and lower plates are assembled after stamping, and the clearance value of all brazed mating surfaces of the parts is 0.21mm-0.30mm;

[0088] When electroplating the lower layer of high-strength steel plate, the concentration of copper ions in the plating solution is 8.0 g / L, the concentration of zinc ions is 5.0 g / L, the concentration of manganese ions is 0.1 g / L, and the concentration of trivalent chromium ions is 1.0 g / L. The content of other elements is added according to the composition ratio of the alloy coating.

[0089] When electroplating the lower high-strength steel plate, the electroplating temperature is 40℃, the pH value of the plating solution is 8.0, the cathode current density is 2.0A / dm2, and the electroplating time is 2.0h.

[0090] Before brazing the upper and lower plates, wipe the surface of the parts with acetone to remove oil, impurities, electroplating solution and other contaminants.

[0091] When brazing the upper and lower plates, the furnace brazing method is used, the brazing temperature is 930℃, and the brazing time is 9 minutes.

[0092] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 4.4%, and the tensile shear strength of the brazed weld was 314 MPa. Under the condition of the battery pack being supported at the bottom, the water-cooled plate and the brazed weld did not produce cracks or tears. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 36.1℃. All of the above meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and no cracks or tears in the water-cooled plate and the brazed weld under the condition of the battery pack being supported at the bottom. Simulation analysis also showed that the battery product performance design requirements of a maximum temperature ≤36.5℃ under normal battery operating conditions were met.

[0093] Example 5:

[0094] The water-cooled plate for the automotive power battery in this embodiment has the following structure and materials: The water-cooled plate assembly includes an upper plate and a lower plate. A cooling circulation channel is set between the upper and lower plates according to factors such as cooling and heat dissipation requirements and cooling water flow rate. The upper and lower plates are connected and sealed by copper brazing. The upper plate is made of T2 pure copper plate with a thickness of 1.6mm. The lower plate is made of high-strength steel plate with a tensile strength of 800MPa. The surface of the high-strength steel plate is electroplated with a copper-zinc alloy coating. The total thickness of the steel plate with the coating is 3.0mm, of which the coating thickness accounts for 15% of the total thickness of the lower plate.

[0095] The composition of the copper-zinc alloy coating is, by mass percentage: Cu 59.0%, Zn 37.0%, Sn 0.8%, Si 0.2%, Mn 1.0%, Fe 0.2%, Cr 1.3%, Ni 0.1%, with the remainder being impurity elements;

[0096] The lower steel plate is electroplated only on the upper surface that contacts the upper copper plate. After electroplating, five points are randomly selected for plating thickness testing. The plating thicknesses are 0.44mm, 0.45mm, 0.46mm, 0.44mm, and 0.45mm, respectively.

[0097] The manufacturing process of the automotive power battery water-cooling plate is as follows: First, a 1.6mm thick T2 pure copper plate is stamped into an upper plate according to the product design structure; second, a copper-zinc alloy coating is electroplated onto the upper surface of a lower high-strength steel plate, and then the coated steel plate is stamped into a lower plate according to the product design structure; finally, the coating on the upper surface of the lower plate is used as a brazing filler metal to braze the upper and lower plates together to form an integrated water-cooling plate assembly.

[0098] The upper and lower plates are assembled after stamping, and the clearance value of all brazed mating surfaces of the parts is 0.23mm-0.30mm;

[0099] When electroplating the lower layer of high-strength steel plate, the concentration of copper ions in the plating solution is 15.0 g / L, the concentration of zinc ions is 8.0 g / L, the concentration of manganese ions is 0.5 g / L, and the concentration of trivalent chromium ions is 0.8 g / L. The content of other elements is added according to the composition ratio of the alloy coating.

[0100] When electroplating the lower high-strength steel plate, the electroplating temperature is 45℃, the pH value of the plating solution is 9.0, the cathode current density is 3.0A / dm2, and the electroplating time is 1.5h.

[0101] Before brazing the upper and lower plates, wipe the surface of the parts with acetone to remove oil, impurities, electroplating solution and other contaminants.

[0102] When brazing the upper and lower plates, the furnace brazing method is used, the brazing temperature is 920℃, and the brazing time is 10 minutes.

[0103] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 2.8%, and the tensile shear strength of the brazed weld was 350 MPa. Under the condition of the battery pack being supported, the water-cooled plate and the brazed weld did not produce cracks or tears. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 35.7℃. All of the above meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and no cracks or tears in the water-cooled plate and the brazed weld under the condition of the battery pack being supported. Simulation analysis also showed that the battery product performance design requirements of a maximum temperature ≤36.5℃ under normal battery operating conditions were met.

[0104] Comparative Example 1:

[0105] Based on Example 1, the lower plate is made of high-strength steel plate with a tensile strength of 780MPa. The gap value of all brazing mating surfaces of the upper and lower plates is adjusted to 0.35mm-0.50mm, the brazing temperature in the furnace is adjusted to 905℃, and all other product structures, materials and manufacturing processes are the same as in Example 1.

[0106] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 9.4%, and the tensile shear strength of the brazed weld was 186 MPa. Cracks appeared in the brazed weld under the condition of battery pack bottom support. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 37.6℃. The porosity, tensile shear strength, and battery pack bottom support test all failed to meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and the water-cooled plate and brazed weld not cracking or tearing under the condition of battery pack bottom support. Simulation analysis showed that the battery product performance design requirements were met for a maximum temperature ≤36.5℃ under normal battery operating conditions.

[0107] Comparative Example 2:

[0108] Based on Example 1, the concentration of the electroplating solution was adjusted to 16.5 g / L for copper ions, 4.0 g / L for zinc ions, 0.8 g / L for manganese ions, and 1.2 g / L for trivalent chromium ions. The content of other elements was added according to the composition ratio of the alloy coating. All other product structures, materials and manufacturing processes were the same as in Example 1.

[0109] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 16.7%, and the tensile shear strength of the brazed weld was 113 MPa. The brazed weld tore under the condition of the battery pack being supported. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 37.1℃. The porosity, tensile shear strength, and battery pack support test results did not meet the requirements of brazed weld porosity ≤5.0%, brazed weld tensile shear strength ≥300 MPa, and the water-cooled plate and brazed weld not cracking or tearing under the condition of the battery pack being supported. Simulation analysis showed that the battery product performance design requirements were met for a maximum temperature ≤36.5℃ under normal battery operating conditions.

[0110] Comparative Example 3:

[0111] Based on Example 1, when electroplating the lower high-strength steel plate, the electroplating temperature was adjusted to 35°C, the pH value of the plating solution was adjusted to 7.5, the cathode current density was adjusted to 3.4A / dm2, and the electroplating time was adjusted to 1.2h. All other product structures, materials and manufacturing processes were the same as in Example 1.

[0112] The water-cooled plate assembly was prepared using the above method. The porosity of the brazed weld was 8.2%, and the tensile shear strength of the brazed weld was 206 MPa. Cracks appeared in the brazed weld under the battery pack support condition. Simulation analysis showed that under normal battery operating conditions, the maximum battery temperature was 36.9℃. The porosity, tensile shear strength, and battery pack support test results did not meet the requirements of brazed weld porosity ≤ 5.0%, brazed weld tensile shear strength ≥ 300 MPa, and the water-cooled plate and brazed weld did not crack or tear under the battery pack support condition. Simulation analysis showed that the battery product performance design requirements were met when the maximum temperature was ≤ 36.5℃ under normal battery operating conditions.

[0113] The test results of Examples 1-5 and Comparative Examples 1-3 demonstrate that the automotive power battery water-cooling plates manufactured using the technical solution of this invention in Examples 1-5 meet the requirements of brazed weld porosity ≤ 5.0%, brazed weld tensile shear strength ≥ 300 MPa, and no cracks or tears in the water-cooling plate and brazed weld under battery pack support conditions. Simulation analysis shows that the battery product performance design requirement of a maximum temperature ≤ 36.5℃ under normal battery operating conditions is met. The automotive power battery water-cooling plates manufactured in Comparative Examples 1-3, which were not manufactured according to the technical solution of this invention, do not meet the battery product performance design requirements.

[0114] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A water-cooled plate for an automotive power battery, characterized in that, The upper plate (1) and the lower plate (2) are included. The upper plate (1) is made of pure copper plate or oxygen-free copper plate. The lower plate (2) includes a high-strength steel plate (2.1) and a copper-zinc alloy plating layer (2.2). The high-strength steel plate (2.1) has a tensile strength greater than 780 MPa. The high-strength steel plate (2.1) is provided with a groove (2.3). The upper surface of the high-strength steel plate (2.1) is electroplated with a copper-zinc alloy plating layer (2.2). The lower bottom surface of the upper plate (1) is attached to the copper-zinc alloy plating layer (2.2) and welded and sealed. The upper plate (1) covers the groove (2.3) of the high-strength steel plate (2.1) to form a cooling circulation channel.

2. The automotive power battery water-cooling plate according to claim 1, characterized in that, The composition of the copper-zinc alloy coating (2.2) is as follows, by mass percentage: Cu 58%~60%, Zn 36%~38%, Sn 0.5%~0.8%, Si 0.1%~0.2%, Mn 0.8%~1.0%, Fe 0.2%~0.5%, Cr 1.2%~1.5%, and Ni 0.1%~0.4%.

3. The automotive power battery water-cooling plate according to claim 1, characterized in that, The thickness of the lower plate (2) is 2.0mm~3.0mm, of which the thickness of the copper-zinc alloy plating layer (2.2) accounts for 8%~15% of the total thickness of the lower plate (2).

4. The automotive power battery water-cooling plate according to claim 1, characterized in that, A copper-zinc alloy plating (2.2) is uniformly electroplated on one side of the upper surface of the high-strength steel plate (2.1). The copper-zinc alloy plating (2.2) is used as a brazing filler metal. The upper plate (1) is brazed and sealed to the lower plate (2) through the copper-zinc alloy plating (2.2).

5. A method for manufacturing a water-cooled plate for an automotive power battery as described in any one of claims 1-4, characterized in that the step... include: S1. Select a pure copper plate or oxygen-free copper plate of preset thickness, process it into shape by stamping according to the product design structure, and obtain the upper plate (1). S2. Select a high-strength steel plate (2.1) of a preset thickness as the base material of the lower plate (2). Through a preset electroplating process, a copper-zinc alloy coating (2.2) is uniformly electroplated on one side of the upper surface of the high-strength steel plate (2.1). Then, according to the product design structure, the high-strength steel plate (2.1) with the copper-zinc alloy coating (2.2) is stamped to form the lower plate (2). S3. The upper plate (1) and the lower plate (2) are attached to each other. The copper-zinc alloy plating layer (2.2) on the upper surface of the high-strength steel plate (2.1) is used as the brazing filler metal to braze the upper plate (1) and the lower plate (2). The gap value of all brazing mating surfaces of the upper plate (1) and the lower plate (2) is ≤0.3mm, so that the upper and lower plates (2) are connected as one piece by brazing and sealing to obtain the water-cooled plate assembly.

6. The method for manufacturing a water-cooled plate for an automotive power battery according to claim 5, characterized in that, In step S2, the plating solution used for electroplating high-strength steel plate (2.1) has a copper ion concentration of 8~15g / L, a zinc ion concentration of 5~10g / L, a manganese ion concentration of 0.1~0.5g / L, and a trivalent chromium ion concentration of 0.3~1.0g / L.

7. The method for manufacturing a water-cooled plate for an automotive power battery according to claim 5, characterized in that, In step S2, during the electroplating of the high-strength steel plate (2.1), the temperature range is 40℃~50℃, the pH value of the plating solution ranges from 8.0 to 9.0, and the cathode current density ranges from 2.0 to 3.0 A / dm³. 2 The electroplating time ranges from 1.5 to 2.0 hours.

8. The method for manufacturing a water-cooled plate for an automotive power battery according to claim 5, characterized in that, In step S3, when brazing the upper plate (1) and the lower plate (2), the furnace brazing method is adopted, the brazing temperature is 920℃~950℃, and the brazing time is 6min~10min.

9. A battery, characterized in that, Including the automotive power battery water cooling plate as described in any one of claims 1-4.

10. A vehicle, characterized in that, Includes the battery as described in claim 9.

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