Corrosion-resistant composite conductor material for automobile battery pack, connecting piece and preparation method

Abstract

The invention discloses a corrosion-resistant composite conductor material for an automobile battery pack, a connector and a preparation method, and relates to the field of automobile battery pack connectors, the composite conductor material comprises a matrix layer and a conductive layer, and a transition layer is arranged between the matrix layer and the conductive layer; the matrix layer is a stainless steel layer, the transition layer is a Ni-P alloy layer, the conductive layer is a pure copper layer, and the matrix layer, the transition layer and the conductive layer are sequentially arranged from inside to outside to form the layered composite conductor material. The base body layer provides support for the conducting layer, the conducting layer completes current conduction, the transition layer is arranged between the base body layer and the conducting layer, the composite conductor material is still not prone to electrochemical corrosion after being used for a long time due to blocking of the transition layer, the safety performance of a new energy automobile battery is improved, and the service life of the new energy automobile battery is prolonged. The technical problems that a metallic nickel material is used as a conductor material at the joint of the positive electrode and the negative electrode of an existing new energy automobile battery pack and a wire, and the corrosion resistance of the metallic nickel material is relatively low are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile battery pack connectors, and in particular to a corrosion-resistant composite conductor material, a connector, and a preparation method for automobile battery packs. Background Art

[0002] Nickel sheets are actively used in battery manufacturing, leveraging the stability of nickel metal to ensure reliable current transmission. Nickel sheets are often used at the junctions between the positive and negative electrodes and the wires in new energy vehicle battery packs. During welding, the nickel sheet contacts the tabs, forming a weld at high temperatures. This welding of wires, tabs, and nickel sheet is then used to connect different battery cells in series.

[0003] That is, the existing new energy vehicle battery pack uses metal nickel as the conductor material between the positive and negative electrodes and the wires. However, the corrosion resistance of metal nickel is low. After long-term use, nickel ions are precipitated in the nickel sheets made directly from metal nickel materials, which makes the nickel sheets prone to electrochemical corrosion, which may cause micro-short circuits in the new energy vehicle batteries, seriously affecting the local safety of new energy vehicles. Summary of the Invention

[0004] In response to the deficiencies in the above-mentioned background technology, the present invention proposes a corrosion-resistant composite conductor material, connector and preparation method for automotive battery packs, which solves the technical problem that the existing new energy vehicle battery packs use metal nickel materials as conductor materials at the connection between the positive and negative electrodes and the wires, and the corrosion resistance of metal nickel materials is low.

[0005] The technical solution of the present invention is achieved as follows: a corrosion-resistant composite conductor material for an automotive battery pack, the composite conductor material comprising a base layer and a conductive layer, wherein a transition layer is provided between the base layer and the conductive layer for preventing electrochemical corrosion between the base layer and the conductive layer; the base layer is a stainless steel layer, the transition layer is a Ni-P alloy layer, and the conductive layer is a pure copper layer, wherein the base layer, the transition layer, and the conductive layer are arranged sequentially from the inside to the outside to form the layered composite conductor material. By providing the conductive layer outside the base layer, the base layer provides support for the conductive layer and simultaneously conducts current, and the transition layer is provided between the base layer and the conductive layer to prevent electrochemical corrosion between the base layer and the conductive layer, thereby further improving the corrosion resistance of the composite conductor material of the present invention. The composite conductor material of the present invention is not susceptible to electrochemical corrosion even after long-term use due to the blocking effect of the transition layer, thereby improving the safety performance of new energy vehicle batteries and solving the technical problem of using nickel metal as a conductor material at the connection between the positive and negative electrodes and the wires of existing new energy vehicle battery packs, which has low corrosion resistance.

[0006] The base layer is a stainless steel layer. The stainless steel layer provides support for the conductive layer and, by leveraging stainless steel's strong corrosion resistance, ensures the service life of the composite conductor material used as a conductor. Base layers made of any type of stainless steel are within the scope of protection of this application; the specific type of stainless steel can be selected based on actual needs.

[0007] The conductive layer is a pure copper layer, which refers to a layered structure formed by high-purity copper with a purity of more than 96%.

[0008] It should be noted that the transition layer is mainly used to block electrochemical corrosion between the base layer and the conductive layer. In addition, the transition layer can be combined with the base layer and the conductive layer respectively to strengthen the bonding force between the base layer and the conductive layer, which is conducive to the formation of the composite conductor material of this application.

[0009] Preferably, the base layer is a 06Cr17Ni12Mo2N stainless steel layer with a yield strength of ≥450MPa and a thickness of 0.5-1.0mm. The base layer preferably uses 06Cr17Ni12Mo2N stainless steel because it contains elements such as chromium, nickel, molybdenum and nitrogen. These components enable it to perform well in oxidizing and weakly corrosive environments, and can resist corrosion from a variety of corrosive media such as the atmosphere, water, acid, and alkali, especially pitting and crevice corrosion caused by chloride ions. In addition, 06Cr17Ni12Mo2N stainless steel has high temperature resistance and is suitable for high-temperature working environments. In order to ensure that the yield strength of the base layer is ≥450MPa, the fatigue resistance can be improved through a cold rolling process.

[0010] The nitrogen content of the substrate layer of the present application is preferably controlled at 0.12-0.18wt% and the density is 7.4g / cm³, and the grain size is refined to ASTM grade 8-10, because the nitrogen content is controlled at 0.12-0.18wt% and the grain size is refined to ASTM grade 8-10, which can effectively reduce the impact of the substrate layer on the mold life.

[0011] Preferably, the transition layer is an amorphous coating with a thickness of 3-5 μm. The reason for the amorphous coating is that its atoms are disordered and lack a distinct crystalline structure. Amorphous coatings generally offer better corrosion resistance than crystalline coatings. The surface of an amorphous coating is fine and uniform, free of microcracks, which helps inhibit the formation of corrosion microcells, thereby further improving its corrosion resistance.

[0012] The phosphorus content of the transition layer is preferably controlled at 6-8 wt %, because a phosphorus content of 6-8 wt % is beneficial to reducing the impact of the transition layer on the life of the mold.

[0013] A connector is made from the composite conductor material described above, and is provided with a crimping tail portion for connection to a conductor, the crimping tail portion being integrally connected to the base layer. When the connector and the conductor are welded, the crimping tail portion is riveted to the conductor, thereby improving the connection strength between the connector and the conductor.

[0014] Preferably, the crimping tail includes a first crimping tail and a second crimping tail, and the first crimping tail and the second crimping tail are respectively connected to the base layer as a whole; the two first crimping tails are cross-arranged on the base layer. The first crimping tail and the second crimping tail are used to hold the conductor together, thereby jointly improving the connection strength between the connector and the conductor. The first crimping tail corresponds to holding the insulation layer of the conductor, and the second crimping tail corresponds to holding the conductor of the conductor. The first crimping tail is cross-arranged on the base layer, and the two cross-arranged first crimping tails are used to wrap and hold the insulation layer of the conductor together; the second crimping tail is also cross-arranged on the base layer, and the two cross-arranged second crimping tails are used to wrap and hold the insulation layer of the conductor together.

[0015] Preferably, the inner side of the second crimping tail is provided with concave or convex ribs for increasing the contact area with the conductor; a plurality of such concave or convex ribs are provided on the inner side of the second crimping tail. The arrangement of the concave or convex ribs on the inner side of the second crimping tail increases the contact area between the second crimping tail and the conductor when the second crimping tail is clamped against the conductor, thereby enhancing the tensile strength of the conductor attachment and ensuring a reliable connection. The number of concave or convex ribs provided along the inner side of the second crimping tail can be determined based on actual needs.

[0016] Preferably, the connector is provided with a positioning hole adapted to fit the tab. The positioning hole not only ensures the correct positioning of the connector and the tab on the vehicle battery pack, but also strengthens the fixing strength between the connector and the tab on the vehicle battery pack.

[0017] A preparation method, which is used to prepare the above-mentioned connector, comprises the following steps: Step 1: first, the base layer is cut, and then the base layer is chemically degreased, water-washed, laser-cleaned and activated in sequence; Step 2: then the base layer is chemically plated with a Ni-P layer, and then the base layer plated with the Ni-P layer is water-washed; Step 3: then a conductive layer is pulse-plated, and then passivation, drying, stamping and packaging are carried out in sequence.

[0018] Preferably, the laser cleaning in step 1 involves removing the surface oxide layer using a laser with a wavelength of 1064 nm. This application utilizes a laser cleaning process to replace existing processes such as pickling and pulsed nano-copper electroplating, ensuring coating adhesion (ASTM D3359 Grade 4B) and microscopic uniformity, while avoiding intergranular corrosion caused by traditional pickling. When the connector formed using the preparation method of this application is tested for coating adhesion using automated EIS (electrochemical impedance spectroscopy), the contact resistance fluctuation rate is significantly reduced to less than 2%. The activation treatment in step 1 involves soaking in a sulfuric acid-thiourea system activation solution for 30 seconds at room temperature. The sulfuric acid-thiourea system activation solution is a solution formed by adding H2SO4 with a concentration gradient of 10% to 0.1 g / L of thiourea. This activation treatment enhances the bonding between the substrate layer and the transition layer.

[0019] Preferably, the pulse-plated conductive layer in step 3 is a nanocrystalline coating formed by pulse electroplating high-purity copper with a purity of 96% or greater, with a thickness of 12-15 μm. The pulse electroplating conditions are preferably a current density of 3.5 A / dm², a duty cycle of 25%, and a frequency of 1000 Hz, with a grain size of ≤0.8 μm on the nanocrystalline coating. In this case, the nanocrystalline coating exhibits excellent corrosion resistance. A conductive layer is formed by pulse electroplating high-purity copper with a purity of more than 96%. The connector is tested under a 100A DC operating condition. The contact resistance of the connector is ≤0.08mΩ, which is 33% lower than that of a nickel sheet. The passivation in step 3 refers to placing the connector prepared by the above preparation method in a chromate passivation solution for passivation. After passivation, a dense oxide film is formed on the connector. The pH of the chromate passivation solution is preferably controlled at 3.5-4.0 to form a dense oxide film of 0.2-0.5μm. After the dense oxide film of 0.2-0.5μm is formed on the connector, it passes a salt spray test for 3000 hours without red rust.

[0020] Beneficial effects of the present invention: 1. By setting a conductive layer on the outside of the base layer, the base layer is used to provide support for the conductive layer, and the conductive layer is used to complete the conduction of current. In addition, the present application sets a transition layer between the base layer and the conductive layer, and uses the transition layer to block electrochemical corrosion between the base layer and the conductive layer, thereby further improving the corrosion resistance of the composite conductor material of the present application. After long-term use, the composite conductor material of the present application is still not prone to electrochemical corrosion due to the blocking of the transition layer, which is beneficial to improving the safety performance of new energy vehicle batteries.

[0021] 2. The transition layer of the present application is an amorphous coating because the atomic arrangement of the amorphous coating is disordered and there is no obvious crystal structure. The corrosion resistance of the amorphous coating is usually better than that of the crystalline coating. The surface of the amorphous coating is fine and uniform without microcracks, which helps to inhibit the formation of corrosion microcells, thereby further improving its corrosion resistance.

[0022] 3. When the connector is welded to the wire, the crimping tail is riveted to the wire, wherein the crimping tail includes a first crimping tail and a second crimping tail. The first crimping tail and the second crimping tail are used to hold the wire together, thereby improving the connection strength between the connector and the wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 Schematic diagram of the composite conductor material of the present invention.

[0025] Figure 2 3 is a cross-sectional SEM image of the conductive layer of the present invention.

[0026] Figure 3 for Figure 2 Magnified image of .

[0027] Figure 4 Schematic diagram of the connector of the present invention.

[0028] Figure 5 It is a schematic diagram of the expansion molding of the connector of the present invention.

[0029] Figure 6 Schematic diagram of the installation of the connector of the present invention on the battery pack.

[0030] Figure 7 for Figure 6 A partial enlarged view of .

[0031] Figure 8 Flow chart of the preparation method of the present invention.

[0032] In the figure: 1 base layer, 2 transition layer, 3 conductive layer, 4 crimping tail, 5 concave rib or convex rib, 6 positioning hole, 7 first crimping tail, 8 second crimping tail, 9 car battery pack, 10 tab, 11 connector. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0034] Example 1, a corrosion-resistant composite conductor material for automobile battery pack, such as Figure 1 As shown, the composite conductor material includes a base layer 1 and a conductive layer 3, and a transition layer 2 is provided between the base layer 1 and the conductive layer 3 for blocking electrochemical corrosion between the base layer 1 and the conductive layer 3; the base layer 1 is a stainless steel layer, the transition layer 2 is a Ni-P alloy layer, and the conductive layer 3 is a pure copper layer. The base layer 1, the transition layer 2 and the conductive layer 3 are arranged in sequence from the inside to the outside to form the layered composite conductor material. By setting a conductive layer 3 on the outside of the base layer 1, the base layer 1 is used to provide support for the conductive layer 3, and the conductive layer 3 is used to complete the conduction of current. In addition, the present application sets a transition layer 2 between the base layer 1 and the conductive layer 3, and uses the transition layer 2 to block the electrochemical corrosion between the base layer 1 and the conductive layer 3, thereby further improving the corrosion resistance of the composite conductor material of the present application. After long-term use, the composite conductor material of the present application is still not prone to electrochemical corrosion due to the blocking of the transition layer 2, which is beneficial to improving the safety performance of new energy vehicle batteries, and solves the technical problem that the existing new energy vehicle battery pack uses metal nickel material as the conductor material at the connection between the positive and negative electrodes and the wires, and the metal nickel material has low corrosion resistance.

[0035] The base layer 1 is a stainless steel layer. The stainless steel layer provides support for the conductive layer 3 and, by leveraging the corrosion resistance of stainless steel, ensures the service life of the composite conductor material used as a conductor. Base layers 1 made of any type of stainless steel are within the scope of protection of this application; the specific type of stainless steel can be selected based on actual needs.

[0036] The conductive layer 3 is a pure copper layer, which refers to a layered structure formed by high-purity copper with a purity of more than 96%. The cross-sectional SEM image of the conductive layer 3 is as follows: Figure 2 and Figure 3 As shown, according to Figure 2 and Figure 3 The cross-sectional SEM image of the conductive layer 3 shows the grain size, which means that the conductive layer 3 on the composite conductor material of the present application has good corrosion resistance.

[0037] It should be noted that the transition layer 2 is primarily intended to prevent electrochemical corrosion between the base layer 1 and the conductive layer 3. Furthermore, the transition layer 2 can be bonded to the base layer 1 and the conductive layer 3, respectively, strengthening the bonding between the base layer 1 and the conductive layer 3, thereby facilitating the formation of the composite conductor material of this application. Laser cleaning can be used in place of processes such as acid cleaning and pulse electroplating of nano-copper layers to ensure the bonding strength (ASTM D3359 Grade 4B) and microscopic uniformity between the base layer 1 and the transition layer 2. When the laser-cleaned base layer 1 and the transition layer 2 are tested for coating bonding strength using automated EIS (electrochemical impedance spectroscopy), the contact resistance fluctuation rate is less than 2%.

[0038] Example 2, based on Example 1, a corrosion-resistant composite conductor material for a car battery pack, such as Figure 1 As shown, the base layer 1 is a 06Cr17Ni12Mo2N stainless steel layer with a yield strength of ≥450MPa and a thickness of 0.5-1.0mm. The base layer 1 preferably uses 06Cr17Ni12Mo2N stainless steel because it contains elements such as chromium, nickel, molybdenum, and nitrogen. These components enable it to perform well in oxidizing and weakly corrosive environments, and can resist corrosion from a variety of corrosive media such as air, water, acid, and alkali. It is particularly resistant to pitting and crevice corrosion caused by chloride ions. Furthermore, 06Cr17Ni12Mo2N stainless steel is resistant to high temperatures and is suitable for high-temperature working environments. To ensure that the yield strength of the base layer 1 is ≥450MPa, fatigue resistance can be improved through a cold rolling process.

[0039] The nitrogen content of the substrate layer 1 of the present application is preferably controlled at 0.12-0.18 wt% and the density is 7.4 g / cm³, and the grain size is refined to ASTM 8-10. This is because controlling the nitrogen content at 0.12-0.18 wt% and refining the grain size to ASTM 8-10 can effectively reduce the impact of the substrate layer 1 on the mold life.

[0040] Example 3, based on Example 2, a corrosion-resistant composite conductor material for a car battery pack, such as Figure 1 As shown, the transition layer 2 is an amorphous coating with a thickness of 3-5 μm. The reason for this is that the atoms in an amorphous coating are disordered and lack a distinct crystalline structure. Amorphous coatings generally offer superior corrosion resistance to crystalline coatings. The surface of an amorphous coating is fine and uniform, free of microcracks, which helps inhibit the formation of corrosion microcells, thereby further improving its corrosion resistance.

[0041] The phosphorus content of the transition layer 2 is preferably controlled at 6-8 wt %, because a phosphorus content of 6-8 wt % is beneficial to reducing the impact of the transition layer 2 on the life of the mold.

[0042] In the implementation of Example 3, the substrate layer 1 is first cut, and then chemically degreased, washed, laser cleaned, and activated. Laser cleaning involves removing the surface oxide layer using a 1064nm laser. Activation involves soaking the substrate in a sulfuric acid-thiourea activation solution for 30 seconds at room temperature. The sulfuric acid-thiourea activation solution is a solution formed by adding 10% H2SO4 to 0.1g / L thiourea. The substrate layer 1 is then electrolessly plated with a Ni-P layer, and then washed. The electroless Ni-P plating uniformly covers the surface of the substrate layer 1, blocking the electrochemical corrosion path between the substrate layer 1 and the conductive layer 3. The process parameters for the electroless Ni-P plating are: temperature 85°C ± 2°C, pH 4.5-5.0, and deposition rate 10μm / h8. The conductive layer 3 is then pulse-plated to form the composite conductor material of Example 3.

[0043] Example 4, based on any one of Examples 1 to 3, a connector, such as Figure 4 、 Figure 5 、 Figure 6 and Figure 7 As shown, the connector 11 is made of the composite conductor material mentioned above, and the connector 11 is provided with a crimping tail 4 connected to the wire, and the crimping tail 4 is integrally connected to the base layer 1. When the connector 11 is welded to the wire, the crimping tail 4 is riveted to the wire to improve the connection strength between the connector 11 and the wire. The connector is designed in a chain to meet the requirements of continuous stamping production. Compared with the single-punch production process of nickel sheets, the production sales volume and material utilization rate are significantly improved, and the unit cost of the connector is increased by 30%-40% compared with the comprehensive cost of the nickel sheet process.

[0044] The use of stainless steel sheet terminals, replacing traditional pure nickel sheet terminals, offers several advantages: Comprehensive weight reduction: Through stainless steel material selection (20% substrate thinning) and low-density plating, the average weight reduction per unit is 15-18%. Application flexibility: The stainless steel sheet terminals feature a riveted structure at the end, allowing crimping with wires to achieve arbitrary series connection between module electrodes within the battery. This significantly improves reliability and efficiency compared to traditional nickel sheet welding. Cost comparison: Material cost is 42% lower than nickel sheet (06Cr17Ni12Mo2N unit price ¥58 / kg vs. ¥145 / kg for nickel sheet). Lifespan prediction: Based on the Arrhenius accelerated aging model, the expected service life is ≥15 years (≤10 years for nickel sheet).

[0045] Example 5, based on Example 4, a connecting piece, such as Figure 4 、 Figure 5 、 Figure 6 and Figure 7As shown, the crimping tail 4 includes a first crimping tail 7 and a second crimping tail 8. The first crimping tail 7 and the second crimping tail 8 are each integrally connected to the base layer 1; the two first crimping tails 7 are cross-arranged on the base layer 1. The first crimping tail 7 and the second crimping tail 8 are used to clamp the wire together, thereby improving the connection strength between the connector 11 and the wire. The first crimping tail 7 corresponds to the insulation layer of the wire, and the second crimping tail 8 corresponds to the conductor of the wire. The first crimping tail 7 is cross-arranged on the base layer 1, and the two cross-arranged first crimping tails 7 are used to wrap and clamp the insulation layer of the wire. The second crimping tail 8 is also cross-arranged on the base layer 1, and the two cross-arranged second crimping tails 8 are used to wrap and clamp the insulation layer of the wire. After the first crimping tail 7 and the second crimping tail 8 are used to wrap and clamp the wire, the tensile strength of the connector and the wire is increased to 120N, which is three times the tensile strength of the previous nickel sheet welding 40N, ensuring contact reliability.

[0046] Example 6, based on Example 5, a connecting piece, such as Figure 4 and Figure 5 As shown, the inner side of the second crimping tail 8 is provided with concave or convex ribs 5 to increase the contact area with the conductor. Several of these ribs 5 are arranged on the inner side of the second crimping tail 8. Arranging the concave or convex ribs 5 on the inner side of the second crimping tail 8 increases the contact area between the second crimping tail 8 and the conductor when the second crimping tail 8 is clamped against the conductor, enhancing the tensile strength of the conductor attachment and ensuring a reliable connection. The number of concave or convex ribs 5 provided along the inner side of the second crimping tail 8 can be adjusted based on actual needs.

[0047] Example 7, based on Example 6, a connecting piece, such as Figure 4 and Figure 5 As shown, the connector 11 is provided with a positioning hole 6 adapted to the tab. The positioning hole 6 ensures the positioning and installation of the connector 11 and the tab 10 on the vehicle battery pack 9, ensuring the correct installation position. On the other hand, the positioning hole 6 also strengthens the fixing strength between the connector 11 and the tab 10 on the vehicle battery pack 9.

[0048] The volume resistivity of the above connectors tested is ≤1.58×10⁻ 8 Ω·m, the conductivity is effectively guaranteed. In addition, the weight of the single connector is reduced by ≥15%, which is conducive to achieving lightweight connectors.

[0049] When implementing Example 7, the composite conductor material formed in Example 3 is directly stamped into an expanded connector, such as Figure 5As shown, the concave or convex ribs 5, the positioning holes 6, the first crimping tail 7 and the second crimping tail 8 are directly punched out, and then the first crimping tail 7 and the second crimping tail 8 on the formed and unfolded connector are bent to form the connector of the present application.

[0050] Example 8, based on any one of Examples 4 to 7, a preparation method, such as Figure 8 As shown, the preparation method is used to prepare the above-mentioned connector 11, comprising the following steps: Step 1: first, the base layer 1 is cut, and then the base layer 1 is chemically degreased, water washed, laser cleaned and activated in sequence; Step 2: then the base layer 1 is chemically plated with a Ni-P layer, and then the base layer 1 plated with the Ni-P layer is water washed; Step 3: then the conductive layer 3 is pulse plated, and then passivation, drying, stamping and packaging are performed in sequence.

[0051] The drying, stamping and packaging processes are common processes that can be achieved with existing equipment and will not be described in detail here.

[0052] Example 9, based on Example 8, a preparation method, such as Figure 8 As shown, the laser cleaning in step 1 involves removing the surface oxide layer using a 1064nm wavelength laser. This application utilizes a laser cleaning process to replace existing processes such as pickling and pulsed nano-copper electroplating, ensuring coating adhesion (ASTM D3359 Grade 4B) and microscopic uniformity, while avoiding intergranular corrosion caused by traditional pickling. When the connector formed using the preparation method of this application is tested for coating adhesion using automated EIS (electrochemical impedance spectroscopy), the contact resistance fluctuation rate is significantly reduced to less than 2%. The activation treatment in step 1 involves soaking in a sulfuric acid-thiourea activation solution at room temperature for 30 seconds. The sulfuric acid-thiourea activation solution is formed by adding H2SO4 with a concentration gradient of 10% to 0.1g / L thiourea. The activation treatment enhances the bonding between the substrate layer 1 and the transition layer 2.

[0053] Example 10, based on Example 9, a preparation method, such as Figure 8As shown, the pulse-plated conductive layer 3 in the step three refers to a nanocrystalline coating formed by pulse electroplating high-purity copper with a purity of more than 96%, and the thickness of the conductive layer 3 is 12-15μm. The pulse electroplating conditions are preferably a current density of 3.5A / dm², a duty cycle of 25%, a frequency of 1000Hz, and a grain size of ≤0.8μm on the nanocrystalline coating. At this time, the corrosion resistance of the nanocrystalline coating is better. The conductive layer 3 formed by pulse electroplating high-purity copper with a purity of more than 96% is tested on the connector under 100A DC conditions. The contact resistance of the connector is ≤0.08mΩ, which is 33% lower than that of the nickel sheet; the passivation in step three refers to placing the connector 11 made by the above preparation method in a chromate passivation solution for passivation. After passivation, a dense oxide film is formed on the connector 11, such as Figure 2 and Figure 3 As shown, the pH of the preferred chromate passivation solution is controlled at 3.5-4.0, forming a dense oxide film of 0.2-0.5 μm. After the dense oxide film of 0.2-0.5 μm is formed on the connector 11, a salt spray test in a 5% NaCl solution is carried out for 3000 hours without red rust.

[0054] When implementing Example 10, step 1: first, the base layer 1 is cut, and then the base layer 1 is subjected to chemical degreasing, water washing, laser cleaning and activation treatment in sequence; laser cleaning refers to the use of a laser with a wavelength of 1064nm to remove the surface oxide layer; activation treatment refers to the use of a sulfuric acid-thiourea system activation solution, soaking at room temperature for 30 seconds, and the sulfuric acid-thiourea system activation solution refers to a liquid formed by adding H2SO4 with a concentration gradient of 10% to 0.1g / L thiourea.

[0055] Step 2: The base layer 1 is then electrolessly plated with a Ni-P layer, and the base layer 1 plated with the Ni-P layer is then washed with water; when the Ni-P layer is electrolessly plated, the Ni-P layer uniformly covers the surface of the base layer 1, blocking the electrochemical corrosion path between the base layer 1 and the conductive layer 3; the process parameters for the electroless plating of the Ni-P layer are: temperature 85°C ± 2°C, pH value 4.5-5.0, and deposition rate 10μm / h8.

[0056] Step 3: Pulse plating is then performed on the conductive layer 3, followed by passivation, drying, stamping, and packaging. The nanocrystalline coating is formed by pulse plating high-purity copper with a purity of 96% or greater, with a thickness of 12-15 μm. The pulse plating conditions are preferably a current density of 3.5 A / dm², a duty cycle of 25%, and a frequency of 1000 Hz. Passivation is performed by placing the connector 11 prepared by the above method in a chromate passivation solution, forming a dense oxide film on the connector 11 after passivation. The pH of the chromate passivation solution is preferably controlled between 3.5 and 4.0.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A corrosion-resistant composite conductor material for automotive battery packs, characterized in that: The composite conductor material comprises a base layer (1) and a conductive layer (3); a transition layer (2) is provided between the base layer (1) and the conductive layer (3) for blocking electrochemical corrosion between the base layer (1) and the conductive layer (3); the base layer (1) is a stainless steel layer, the transition layer (2) is a Ni-P alloy layer, and the conductive layer (3) is a pure copper layer; the base layer (1), the transition layer (2) and the conductive layer (3) are arranged in sequence from the inside to the outside to form the layered composite conductor material.

2. The corrosion-resistant composite conductor material for an automotive battery pack according to claim 1, characterized in that: The base layer (1) is a stainless steel layer of the type 06Cr17Ni12Mo2N, with a yield strength of ≥450MPa, and a thickness of the base layer (1) of 0.5-1.0mm.

3. The corrosion-resistant composite conductor material for an automotive battery pack according to claim 2, characterized in that: The transition layer (2) is an amorphous coating, and the thickness of the transition layer (2) is 3-5 μm.

4. A connector, characterized in that: The connector (11) is made of the composite conductor material according to any one of claims 1 to 3, and is provided with a crimping tail (4) connected to the conductor, and the crimping tail (4) is integrally connected to the base layer (1).

5. The connector according to claim 4, wherein: The crimping tail (4) comprises a first crimping tail (7) and a second crimping tail (8), wherein the first crimping tail (7) and the second crimping tail (8) are respectively connected integrally to the base layer (1); the two first crimping tails (7) are cross-arranged on the base layer (1).

6. The connector according to claim 5, characterized in that: The inner side of the second crimping tail (8) is provided with a concave rib or a convex rib (5) for increasing the contact area with the wire; a plurality of the concave ribs or the convex ribs (5) are arranged on the inner side of the second crimping tail (8).

7. The connector according to claim 6, wherein: The connecting piece (11) is provided with a positioning hole (6) adapted to the tab.

8. A preparation method, characterized in that: The preparation method is used to prepare the connector (11) according to any one of claims 4 to 7, comprising the following steps: Step 1: first, the base layer (1) is cut, and then the base layer (1) is subjected to chemical degreasing, water washing, laser cleaning and activation treatment in sequence; Step 2: then, the base layer (1) is subjected to chemical plating of a Ni-P layer, and then the base layer (1) plated with the Ni-P layer is subjected to water washing; Step 3: Then pulse plate the conductive layer (3), and then perform passivation, drying, stamping and packaging in sequence.

9. The preparation method according to claim 8, characterized in that: The laser cleaning in step 1 refers to removing the surface oxide layer using a laser with a wavelength of 1064 nm; the activation treatment in step 1 refers to using a sulfuric acid-thiourea system activation solution and soaking at room temperature.

10. The preparation method according to claim 9, characterized in that: The pulse plating of the conductive layer (3) in the step 3 refers to a nanocrystalline coating formed by pulse electroplating high-purity copper with a purity of more than 96%, and the thickness of the conductive layer (3) is 12-15 μm; the passivation in the step 3 refers to placing the connector (11) formed by the above preparation method in a chromate passivation solution to achieve passivation.

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