Stainless steel material for explosion-proof ring of vehicle battery and preparation method of stainless steel material

Abstract

The invention relates to the technical field of new energy automobile power batteries, in particular to a stainless steel material for an automobile battery explosion-proof ring and a preparation method of the stainless steel material. The functional gradient layer is combined between the stainless steel substrate and the porous electro-catalysis dehydrogenation layer; the porous electro-catalysis hydrogen elimination layer is arranged on the functional gradient layer and faces the inner side of the battery; the transition metal carbide wear-resistant layer is arranged on the surface, facing the outer side of the battery, of the stainless steel substrate, and the transition metal carbide wear-resistant layer is a nanocrystalline niobium carbide layer. Therefore, the problems of structural demand contradiction and poor metal and ceramic interface bonding when the explosion-proof ring of the vehicle battery integrates catalysis and wear-resistant functions in the prior art are solved.

Description

Technical Field

[0001] This application relates to the field of new energy vehicle power battery technology, and in particular to a stainless steel material for explosion-proof rings of vehicle batteries and its preparation method. Background Technology

[0002] With the increasing popularity of electric vehicles, the safety of power batteries has become a focus of public concern. Under conditions of abuse such as overcharging, short circuits, or thermal runaway, the internal electrolyte of a battery decomposes, producing a large amount of hydrogen gas. This causes a sharp increase in the internal pressure of the battery pack, posing a risk of explosion. Traditional battery explosion-proof valves or rings are mainly made of materials such as stainless steel and aluminum alloys, and are designed to rupture under specific pressure to release pressure. This passive protection method has obvious limitations: first, it can only release pressure and cannot eliminate the hydrogen gas hazard that has already been generated; second, its surface does not have special protection, and it is prone to wear or premature failure under long-term vibration or the high-temperature, high-speed airflow generated by extreme thermal runaway.

[0003] In recent years, researchers have attempted to develop materials with electrocatalytic hydrogen evolution function to decompose hydrogen into water in the early stages of hydrogen production, eliminating the risk at its source. For example, published literature reports that transition metal phosphides and sulfides such as Ce / Ni / Fe exhibit good electrocatalytic hydrogen evolution activity in alkaline media. Meanwhile, transition metal nitride and carbide coatings such as TiN and TiAlN are widely used for surface strengthening of tools and molds due to their high hardness and wear resistance.

[0004] However, integrating catalytic and wear-resistant protection functions into a specific component like an explosion-proof ring for automotive batteries presents a fundamental technical contradiction: catalytic function requires a porous structure with a high specific surface area to expose active sites, while wear resistance requires a dense and hard surface to resist erosion. Furthermore, integrating a brittle ceramic catalyst layer onto a metal substrate results in poor interfacial bonding due to the significant differences in physical and chemical properties between the two, making it prone to peeling under thermal or mechanical stress and failing to meet automotive-grade long-term reliability requirements. Summary of the Invention

[0005] This application provides a stainless steel material for explosion-proof rings of automotive batteries and a method for preparing the same, in order to solve the problems of structural contradictions and poor bonding between metal and ceramic interfaces when integrating catalytic and wear-resistant functions in explosion-proof rings of automotive batteries in the prior art.

[0006] This application provides a stainless steel material for explosion-proof rings of automotive batteries, characterized in that it comprises: Stainless steel base; A functional gradient layer is incorporated between the stainless steel substrate and the porous electrocatalytic hydrogen removal layer; The porous electrocatalytic hydrogen removal layer disposed on the functional gradient layer and facing the inside of the battery; and A transition metal carbide wear-resistant layer is disposed on the outer surface of the stainless steel substrate facing the battery, wherein the transition metal carbide wear-resistant layer is a nanocrystalline niobium carbide layer.

[0007] The functional gradient layer is a transition layer in which the chemical composition changes continuously along the thickness direction, wherein the contents of iron, chromium and nickel decrease from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0008] In the functional gradient layer, the content of at least one element selected from cerium and gadolinium increases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0009] The nano-niobium carbide layer is also doped with at least one of titanium, vanadium, and chromium, with a doping amount of 1-10 at.

[0010] The thickness of the nano-niobium carbide layer is 1-5 μm, the average grain size is less than 100 nm, and its Vickers hardness is not less than 28 GPa.

[0011] The porous electrocatalytic hydrogen elimination layer contains rare earth elements cerium or gadolinium, and has a porosity of 20%-60%.

[0012] The stainless steel matrix is ​​austenitic stainless steel with a thickness of 0.1 mm to 2.0 mm.

[0013] This application also proposes a method for preparing a stainless steel material for explosion-proof rings in automotive batteries, comprising the following steps: (1) Cleaning and surface activation pretreatment of the stainless steel substrate; (2) A dual-target co-sputtering method is used to deposit a functional gradient layer on the pretreated stainless steel substrate facing the inner surface of the battery. By continuously adjusting the sputtering power ratio of the two targets during the sputtering process, the content of Fe, Cr and Ni elements in the functional gradient layer decreases from the substrate side to the catalyst layer side, while the content of Ce and Gd elements increases from the substrate side to the catalyst layer side. The dual targets include a stainless steel target and a target material containing rare earth elements. The sputtering temperature is 100-300℃, the working pressure is 0.1-1.0Pa, and the bias voltage is -50 to -200V. (3) A porous electrocatalytic hydrogen elimination layer is prepared on the surface of the functional gradient layer by electrochemical deposition, wherein the deposition voltage is 1-5V and the deposition time is 10-60min; It should be noted that, under conditions of localized heating inside the battery and the presence of an electrolyte, the porous electrocatalytic hydrogen elimination layer can catalyze the electrochemical oxidation of hydrogen (e.g., H2 → 2H+). + + 2e -The protons produced can be absorbed by the electrolyte or further react to form water, thereby reducing the partial pressure of hydrogen. Even in an oxygen-deficient environment, this catalyst layer can promote hydrogen recombination or storage through surface adsorption and dissociation, thus slowing down the pressure rise.

[0014] (4) A nanocrystalline niobium carbide wear-resistant layer is deposited on the outer surface of the stainless steel substrate facing the battery by magnetron sputtering. The sputtering temperature is 200-400℃, the sputtering power is 100-300W, the working pressure is 0.2-1.5Pa, and the bias voltage is -100 to -300V.

[0015] The electrolyte used in step (3) for electrochemical deposition contains at least one of cerium salt, gadolinium salt, nickel salt, phosphate, sulfide, or nitride precursor.

[0016] This application also proposes an explosion-proof ring for automotive batteries, which is made of the stainless steel material used for explosion-proof rings for automotive batteries.

[0017] Therefore, this application has at least the following beneficial effects: (1) In the embodiments of this application, the porous electrocatalytic hydrogen elimination layer with the explosion-proof ring facing the inside of the battery has rare earth elements such as Ce and Gd and transition metal sites on its surface. Under the environment of increased hydrogen partial pressure inside the battery, it can act as a highly efficient catalyst to significantly reduce the electrochemical oxidation of hydrogen (H2→2H). + +2e - The activation energy of a reaction, or a complex reaction. This reaction converts gaseous hydrogen into protons or water, actively eliminating the risk of deflagration from the chemical source. Simultaneously, the outer-facing nanocrystalline niobium carbide wear-resistant layer, through its extremely high hardness and dense structure, passively resists mechanical wear and erosion caused by thermal runaway or the external environment, ensuring the physical integrity of the valve body structure. (2) This application adds a functional gradient layer between the stainless steel substrate and the porous electrocatalytic hydrogen removal layer. Through a continuous and gradual transition of chemical composition along the thickness direction, the content of matrix elements such as iron, chromium, and nickel decreases towards the catalyst layer side, while the content of rare earth elements such as Ce and Gd increases towards the catalyst layer side. At the same time, it provides a good bonding interface for the subsequently deposited porous electrocatalytic hydrogen removal layer (containing elements such as P, S, and N). Under thermal cycling or external force, this gradient layer can actively absorb and disperse interfacial stress, inhibit the initiation and propagation of cracks caused by stress concentration, and significantly improve the interfacial bonding force, meeting the structural stability requirements for long-term use in automotive applications. (3) The nanocrystalline structure obtained through process control in the embodiments of this application introduces a large number of grain boundaries. According to the Hall-Page effect, grain boundaries can effectively hinder dislocation movement, thereby significantly improving the hardness and strength of the material. At the same time, the fine grains are conducive to the uniform distribution of stress and the deflection of microcracks when subjected to load, avoiding the brittle peeling of traditional hard coatings. The solid solution formed by doping with elements such as Ti, V, and Cr further causes lattice distortion, producing a solid solution strengthening effect, which synergistically improves the comprehensive mechanical properties and thermal stability, ensuring its durability under extreme working conditions; (4) The rare earth elements such as Ce and Gd introduced into the catalyst layer in the embodiments of this application can flexibly store and release electrons during the reaction, effectively regulate the electronic state density of the active center, optimize the adsorption / desorption energy of the reaction intermediate, and thus enhance the intrinsic catalytic activity. The porosity of 20%-60% forms a three-dimensional interconnected mesoporous-macroporous network, which not only greatly increases the number of exposed active sites, but also provides a suitable environment for the gaseous reactants (H2) and products (H2). + The rapid diffusion of H2O provides a channel, reduces mass transfer limitations, and ensures a continuous and efficient reaction at high current densities. (5) The preparation method of this invention adopts inner catalysis and outer wear resistance, avoiding thermal damage or contamination of the inner sensitive catalytic layer during the deposition process of the outer high-temperature wear-resistant layer. The functionally graded layer is prepared in situ using magnetron sputtering technology. By adjusting the multi-target power in real time, atomic-scale compositional gradient control can be achieved, which is key to obtaining the ideal transition structure. Electrochemical deposition can uniformly grow catalytic precursors on complex surfaces, and combined with subsequent heat treatment, the target phosphorus / sulfur / nitride phases are generated in situ, exhibiting good process compatibility. The entire process combines the advantages of physical vapor deposition and electrochemical deposition, with a clear parameter window, facilitating large-scale production and quality control.

[0018] This solves the structural contradictions and poor bonding between metal and ceramic interfaces in existing technologies when integrating catalytic and wear-resistant functions into the explosion-proof ring of automotive batteries.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Detailed Implementation

[0020] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the embodiments of this application, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0022] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0023] Example 1 This application provides a stainless steel material for explosion-proof rings of automotive batteries, characterized in that it comprises: Stainless steel base; A functional gradient layer is bonded between a stainless steel substrate and a porous electrocatalytic hydrogen removal layer; A porous electrocatalytic hydrogen removal layer disposed on the functional gradient layer and facing the inside of the battery; and A transition metal carbide wear-resistant layer is disposed on the outer surface of the stainless steel substrate facing the battery, wherein the transition metal carbide wear-resistant layer is a nanocrystalline niobium carbide layer.

[0024] The functional gradient layer is a transition layer in which the chemical composition changes continuously along the thickness direction. The content of iron, chromium and nickel decreases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0025] In the functionally graded layer, the content of elements selected from cerium and gadolinium increases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0026] The nano-niobium carbide layer is also doped with titanium, with a doping amount of 1 at.

[0027] The niobium carbide nanolayer has a thickness of 1 μm, an average grain size of less than 100 nm, and a Vickers hardness of not less than 28 GPa.

[0028] The porous electrocatalytic hydrogen elimination layer contains the rare earth element cerium and has a porosity of 20%.

[0029] The stainless steel matrix is ​​austenitic stainless steel with a thickness of 0.1 mm.

[0030] This application also proposes a method for preparing a stainless steel material for explosion-proof rings in automotive batteries, comprising the following steps: (1) Cleaning and surface activation pretreatment of the stainless steel substrate; (2) A dual-target co-sputtering method is used to deposit a functional gradient layer on the inner surface of the pretreated stainless steel substrate facing the battery. By continuously adjusting the sputtering power ratio of the two targets during the sputtering process, the content of Fe, Cr and Ni elements in the functional gradient layer decreases from the substrate side to the catalyst layer side, while the content of Ce and Gd elements increases from the substrate side to the catalyst layer side. The dual targets include a stainless steel target and a target material containing rare earth elements. The sputtering temperature is 100℃, the working pressure is 0.1Pa, and the bias voltage is -50V. (3) A porous electrocatalytic hydrogen elimination layer was prepared on the surface of the functional gradient layer by electrochemical deposition, wherein the deposition voltage was 1V and the deposition time was 10min; (4) A nanocrystalline niobium carbide wear-resistant layer was deposited on the outer surface of the stainless steel substrate facing the battery by magnetron sputtering. The sputtering temperature was 200℃, the sputtering power was 100W, the working pressure was 0.2Pa, and the bias voltage was -100V.

[0031] In step (3), the electrolyte used for electrochemical deposition contains at least one of cerium salt and gadolinium salt.

[0032] This application also proposes an explosion-proof ring for automotive batteries, which is made of stainless steel material.

[0033] Example 2 This application provides a stainless steel material for explosion-proof rings of automotive batteries, characterized in that it comprises: Stainless steel base; A functional gradient layer is bonded between a stainless steel substrate and a porous electrocatalytic hydrogen removal layer; A porous electrocatalytic hydrogen removal layer disposed on the functional gradient layer and facing the inside of the battery; and A transition metal carbide wear-resistant layer is disposed on the outer surface of the stainless steel substrate facing the battery, wherein the transition metal carbide wear-resistant layer is a nanocrystalline niobium carbide layer.

[0034] The functional gradient layer is a transition layer in which the chemical composition changes continuously along the thickness direction. The content of iron, chromium and nickel decreases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0035] In the functionally graded layer, the content of cerium increases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0036] The nano-niobium carbide layer is also doped with vanadium, with a doping amount of 5 at.

[0037] The niobium carbide nanolayer has a thickness of 3 μm, an average grain size of less than 100 nm, and a Vickers hardness of not less than 28 GPa.

[0038] The porous electrocatalytic hydrogen removal layer contains the rare earth element gadolinium and has a porosity of 40%.

[0039] The stainless steel matrix is ​​austenitic stainless steel with a thickness of 1.0 mm.

[0040] This application also proposes a method for preparing a stainless steel material for explosion-proof rings in automotive batteries, comprising the following steps: (1) Cleaning and surface activation pretreatment of the stainless steel substrate; (2) A dual-target co-sputtering method is used to deposit a functional gradient layer on the pretreated stainless steel substrate facing the inner surface of the battery. By continuously adjusting the sputtering power ratio of the two targets during the sputtering process, the content of Fe, Cr and Ni elements in the functional gradient layer decreases from the substrate side to the catalyst layer side, while the content of Ce and Gd elements increases from the substrate side to the catalyst layer side. The dual targets include a stainless steel target and a target material containing rare earth elements. The sputtering temperature is 200℃, the working pressure is 0.5Pa, and the bias voltage is -100V. (3) A porous electrocatalytic hydrogen elimination layer was prepared on the surface of the functionally graded layer by electrochemical deposition, wherein the deposition voltage was 3V and the deposition time was 40min; (4) A nanocrystalline niobium carbide wear-resistant layer was deposited on the outer surface of the stainless steel substrate facing the battery by magnetron sputtering. The sputtering temperature was 300℃, the sputtering power was 200W, the working pressure was 1.0Pa, and the bias voltage was -200V.

[0041] In step (3), the electrolyte used for electrochemical deposition includes at least one of nickel salt and phosphate.

[0042] Example 3 This application provides a stainless steel material for explosion-proof rings of automotive batteries, characterized in that it comprises: Stainless steel base; A functional gradient layer is bonded between a stainless steel substrate and a porous electrocatalytic hydrogen removal layer; A porous electrocatalytic hydrogen removal layer disposed on the functional gradient layer and facing the inside of the battery; and A transition metal carbide wear-resistant layer is disposed on the outer surface of the stainless steel substrate facing the battery, wherein the transition metal carbide wear-resistant layer is a nanocrystalline niobium carbide layer.

[0043] The functional gradient layer is a transition layer in which the chemical composition changes continuously along the thickness direction. The content of iron, chromium and nickel decreases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0044] In the functionally graded layer, the content of gadolinium increases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

[0045] The nano-niobium carbide layer is also doped with chromium, with a doping amount of 10 at.

[0046] The niobium carbide nanolayer has a thickness of 5 μm, an average grain size of less than 100 nm, and a Vickers hardness of not less than 28 GPa.

[0047] The porous electrocatalytic hydrogen removal layer contains the rare earth element cerium and has a porosity of 60%.

[0048] The stainless steel base is austenitic stainless steel with a thickness of 2.0 mm.

[0049] This application also proposes a method for preparing a stainless steel material for explosion-proof rings in automotive batteries, comprising the following steps: (1) Cleaning and surface activation pretreatment of the stainless steel substrate; (2) A dual-target co-sputtering method is used to deposit a functional gradient layer on the pretreated stainless steel substrate facing the inner surface of the battery. By continuously adjusting the sputtering power ratio of the two targets during the sputtering process, the content of Fe, Cr and Ni elements in the functional gradient layer decreases from the substrate side to the catalyst layer side, while the content of Ce and Gd elements increases from the substrate side to the catalyst layer side. The dual targets include a stainless steel target and a target material containing rare earth elements. The sputtering temperature is 300℃, the working pressure is 1.0Pa, and the bias voltage is -200V. (3) A porous electrocatalytic hydrogen elimination layer was prepared on the surface of the functionally graded layer by electrochemical deposition, wherein the deposition voltage was 5V and the deposition time was 60min; (4) A nanocrystalline niobium carbide wear-resistant layer was deposited on the outer surface of the stainless steel substrate facing the battery by magnetron sputtering. The sputtering temperature was 400℃, the sputtering power was 300W, the working pressure was 1.5Pa, and the bias voltage was -300V.

[0050] In step (3), the electrolyte used for electrochemical deposition contains at least one of sulfide or nitride precursors.

[0051] Comparative Example 1 This comparative example provides a stainless steel material for explosion-proof rings of automotive batteries and its preparation method. The only difference between this example and Example 1 is that it does not contain a functionally graded layer. Instead, a porous electrocatalytic hydrogen elimination layer is directly prepared on the stainless steel substrate facing the inner surface of the battery. The other components, component contents, and preparation process are the same as in Example 1.

[0052] Comparative Example 2 This comparative example provides a stainless steel material for explosion-proof rings of automotive batteries and its preparation method. The only difference between this example and Example 1 is that the nanocrystalline niobium carbide layer is not doped with titanium, vanadium, or chromium, and is a pure nanocrystalline niobium carbide layer. The other components, component contents, and preparation process are the same as in Example 1.

[0053] Comparative Example 3 This comparative example provides a stainless steel material for explosion-proof rings of automotive batteries and its preparation method. The only difference between this example and Example 1 is that in step (3), magnetron sputtering is used instead of electrochemical deposition to prepare a porous electrocatalytic hydrogen elimination layer. Magnetron sputtering uses a composite target containing phosphorus, sulfur, and nitrogen elements or introduces the corresponding reaction gas. The remaining components, component content, and preparation process are the same as in Example 1.

[0054] Performance testing The hydrogen elimination performance of the stainless steel materials of the vehicle battery explosion-proof rings prepared in Examples 1-3 and Comparative Examples 1-3 was analyzed using the hydrogen elimination rate test method. The hydrogen environment of battery thermal runaway was simulated. The samples were placed in a sealed reaction chamber, and hydrogen gas was introduced to maintain the initial hydrogen partial pressure at 50 kPa and the temperature at 85°C. The change of hydrogen concentration in the chamber was monitored within 1 hour, and the hydrogen elimination rate was calculated. The performance test data are shown in Table 1.

[0055] Table 1 Hydrogen elimination rate test

[0056] As shown in Table 1, the stainless steel materials of the vehicle battery explosion-proof rings prepared in Examples 1-3 of this invention all exhibit excellent hydrogen elimination performance. The hydrogen elimination rate shows a significant increasing trend with the optimization of the porosity of the porous electrocatalytic hydrogen elimination layer and the preparation process parameters: Example 1, with a porosity of 20%, has a hydrogen elimination rate of 4.30 mL / (cm²). 2 •h); Example 3 showed that the porosity was increased to 60%, and the electrochemical deposition parameters were optimized, with a hydrogen elimination rate of 7.90 mL / (cm). 2 (h) represents an 83.7% improvement over Example 1. This result fully demonstrates the effectiveness of the technical solution of this application: the Ce and Gd rare earth elements in the porous electrocatalytic hydrogen removal layer can adjust the electronic state density of the active centers, and the 20%-60% porosity forms a three-dimensional interconnected network, which not only increases the exposure of active sites but also provides channels for hydrogen diffusion, significantly improving the hydrogen removal efficiency; the functional gradient layer ensures that the catalyst layer is tightly bonded to the substrate, avoiding catalyst layer detachment from affecting the hydrogen removal effect.

[0057] In contrast, the hydrogen elimination rates of Comparative Examples 1-3 were significantly lower, and showed a stepwise decrease with the absence of core structures or processes: In Comparative Example 1 (lacking a functional gradient layer), the catalyst layer was not firmly bonded to the substrate, and partial detachment resulted in a hydrogen elimination rate of only 2.04 mL / (cm²). 2 •h); Comparative Example 2 (pure nanocrystalline niobium carbide layer without doping) did not directly affect hydrogen elimination, but the insufficient thermal stability of the wear-resistant layer indirectly affected the working condition of the catalyst layer, with a hydrogen elimination rate of 2.48 mL / (cm). 2·h); Comparative Example 3 (catalyst layer prepared by magnetron sputtering instead of electrochemical deposition) had insufficient porosity, few exposed active sites, and the lowest hydrogen elimination rate of only 1.16 mL / (cm). 2 •h). The interface enhancement effect of the functionally graded layer and the precise control of porosity by the electrochemical deposition process are the core to ensure efficient hydrogen removal. Without these, the intrinsic performance of the catalyst layer cannot be realized, further highlighting the necessity of the technical solution in the embodiments.

[0058] The interfacial bonding force of the stainless steel materials of the vehicle battery explosion-proof rings prepared in Examples 1-3 and Comparative Examples 1-3 was analyzed by the scratch method. A diamond indenter was used to scratch one side of the sample catalyst layer at a load rate of 10 N / min. The critical load at which the interface peeled off was recorded, and the interface state at the scratch was observed. The performance test data are shown in Table 2.

[0059] Table 2 Interface Adhesion Test

[0060] As shown in Table 2, the stainless steel material of the automotive battery explosion-proof ring prepared in Examples 1-3 of this invention exhibits excellent interfacial bonding strength. The critical peel load shows an increasing trend with the optimization of functionally graded layer deposition parameters: the critical load in Example 1 is 32.5 N, while in Example 3, due to the optimization of parameters such as sputtering temperature and power, the gradient layer composition transition is smoother, and the critical load reaches 50.2 N, which is 54.5% higher than that in Example 1. This result stems from the core function of the functionally graded layer: its chemical composition changes continuously along the thickness direction, allowing for a smooth transition between the matrix elements and catalytically related elements, effectively avoiding abrupt changes in physical properties between the metal matrix and the brittle catalytic layer. Under scratch load, it can absorb and disperse interfacial stress, inhibit the initiation and propagation of cracks caused by stress concentration, and significantly improve the interfacial bonding stability.

[0061] In comparison, the interfacial bonding strength of Comparative Examples 1-3 is significantly insufficient: Comparative Example 1 lacks a functionally graded layer, resulting in direct bonding between the catalyst layer and the stainless steel substrate. This leads to sharp differences in physical properties at the interface, with a critical peel load of only 15.3 N, making it prone to peeling and cracking. Comparative Example 2, lacking elemental doping, while not directly affecting interfacial bonding, suffers from insufficient mechanical properties in the wear-resistant layer, indirectly causing uneven stress distribution in the overall structure and the appearance of microcracks at the edges. Comparative Example 3 uses magnetron sputtering to prepare the catalyst layer, resulting in poor interfacial compatibility with the graded layer and weak local bonding. Its critical load of 18.7 N is lower than all other examples. The functionally graded layer is crucial for ensuring interfacial bonding strength; its absence or improper processing can prevent the material from withstanding the stress and impact of long-term automotive-grade use, further validating the rationality of the technical solutions in these examples.

[0062] The wear resistance of the stainless steel materials of the explosion-proof rings for automotive batteries prepared in Examples 1-3 and Comparative Examples 1-3 was analyzed using a ball-disc wear tester. Al2O3 ceramic balls were used as the wear pair, and the load was set to 5N, the rotation speed to 300r / min, and the wear time to 60min. After the test, the wear amount of the sample was weighed, and the Vickers hardness of the wear-resistant layer was also tested. The performance test data are shown in Table 3.

[0063] Table 3 Abrasion resistance test

[0064] As shown in Table 3, the stainless steel material of the automotive battery explosion-proof ring prepared in Examples 1-3 of this invention exhibits excellent wear resistance. The wear amount decreases significantly with the optimization of the nanocrystalline niobium carbide layer parameters, while the Vickers hardness steadily increases: In Example 1, the wear amount is 0.82 mg and the Vickers hardness is 28.5 GPa; in Example 3, due to the increased thickness of the nanocrystalline niobium carbide layer and the synergistic effect of the doping elements, the wear amount is reduced to 0.31 mg and the Vickers hardness reaches 32.8 GPa, with the wear resistance performance improved by 62.2% compared to Example 1. This advantage stems from the synergistic strengthening effect of the nanocrystalline structure and element doping: the nanocrystalline structure introduces a large number of grain boundaries, which, according to the Hall-Page effect, hinder dislocation movement and improve hardness and strength; the doping of Ti, V, and Cr elements forms a solid solution, inducing lattice distortion, further enhancing mechanical properties and thermal stability, enabling the wear-resistant layer to resist mechanical wear and erosion.

[0065] In comparison, the wear resistance of Comparative Examples 1-3 declined significantly: Comparative Example 2, lacking elemental doping, had insufficient mechanical properties in its pure nanocrystalline niobium carbide layer, with a Vickers hardness of only 22.6 GPa, a wear amount of 2.18 mg, localized peeling of the wear-resistant layer, and an inability to guarantee structural integrity; Comparative Example 1, lacking a functionally graded layer, although the wear-resistant layer itself met the performance standards, had poor overall structural stress dispersion capabilities, resulting in a 53.7% increase in wear compared to Example 1; Comparative Example 3, due to improper catalyst layer preparation process, indirectly affected the deposition quality of the wear-resistant layer, resulting in deeper wear marks. Elemental doping is the core element for improving the wear resistance of nanocrystalline niobium carbide layers; its absence prevents the synergistic strengthening effect, highlighting the crucial role of the technical solutions in improving wear resistance.

[0066] The long-term working condition adaptability analysis of the stainless steel materials of the explosion-proof rings for automotive batteries prepared in Examples 1-3 and Comparative Examples 1-3 was carried out using the cycle stability test method. The temperature cycle of automotive batteries was simulated from -40℃ to 85℃ (500 cycles), and hydrogen and air were alternately introduced to simulate the switching of the internal and external environment of the battery. After the cycle, the hydrogen elimination rate retention rate, interfacial bonding force retention rate and wear-resistant layer integrity of the materials were tested. The performance test data are shown in Table 4.

[0067] Table 4 Cyclic stability test

[0068] As shown in Table 4, the stainless steel material of the automotive battery explosion-proof ring prepared in Examples 1-3 of this invention exhibits excellent cycle stability. The retention rates of hydrogen elimination rate and interfacial bonding force are both maintained above 89%, and gradually increase with the optimization of process parameters: the retention rates of the two parameters in Example 1 are 89.3% and 90.5%, respectively; in Example 3, due to the optimal matching degree between the structure of each layer and the process, the retention rates of the two parameters reach 95.8% and 96.2%, respectively, and the state of each layer is intact after cycling. This performance is due to the synergy of the structure of each layer and the compatibility of the preparation process: the layered design of the inner catalyst layer and the outer wear-resistant layer avoids thermal damage to the catalyst layer caused by the deposition of the wear-resistant layer; the functionally graded layer prepared by magnetron sputtering is tightly bonded to the electrochemically deposited catalyst layer, and can play a stable role under temperature cycling stress; the doped and strengthened wear-resistant layer has excellent thermal stability and can resist extreme temperature fluctuations.

[0069] In contrast, the cycling stability of Comparative Examples 1-3 was significantly reduced: Comparative Example 1 lacked a functionally graded layer, exacerbating the interfacial stress concentration problem during cycling, with an interfacial bonding retention rate of only 58.7% and localized catalytic layer peeling; Comparative Example 2 lacked elemental doping, resulting in insufficient thermal stability and mechanical properties of the wear-resistant layer, leading to severe peeling after cycling, with a hydrogen elimination rate retention rate of only 72.3%; Comparative Example 3 suffered from poor interfacial compatibility due to improper catalytic layer preparation process, resulting in catalytic layer detachment and wear-resistant layer cracking after cycling, with both retention rates below 65%. The layered structure design, interfacial reinforcement of the functionally graded layer, and stability of the doped wear-resistant layer in the embodiments jointly ensured the reliability of the material under automotive-grade long-term operating conditions, while the comparative examples, due to the lack of core structure or process, could not adapt to cyclic stress and environmental changes, further demonstrating the advanced nature of the technical solution of this application.

[0070] In summary, this application's embodiments, through rare earth doping and porosity regulation of the porous electrocatalytic hydrogen elimination layer, the interface strengthening effect of the functionally graded layer, and precise control of the electrochemical deposition process, combined with the wear-resistance optimization of the nanocrystalline niobium carbide layer, prepared a high-performance explosion-proof ring material: the porous electrocatalytic hydrogen elimination layer (Ce, Gd doped, 20%-60% three-dimensional through-porosity) combined with the electrochemical deposition process, achieved a hydrogen elimination rate of 4.30-7.90 mL / (cm²) in the material of the embodiments. 2 (·h) (Example 3 showed a 6.8-fold improvement over Comparative Example 3), far superior to the Comparative Example (1.16-2.48 mL / (cm)). 2The functionally graded layer, through parameter optimization, achieves a smooth transition in composition. Combined with the above structure, the critical peel load of the embodiment reaches 32.5-50.2N (no interface damage), which is significantly better than the comparative example (15.3-18.7N, with many peel cracks). The Ti, V, and Cr doped nanocrystalline niobium carbide layer improves wear resistance, resulting in a wear amount as low as 0.31-0.82mg and a Vickers hardness of 28.5-32.8GPa in the embodiment, while the comparative example suffers from severe wear (1.26-2.18mg) and insufficient hardness (22.6-28.3GPa). The synergistic effect of each layer structure and process ensures cycle stability. After 500 temperature cycles, the hydrogen elimination rate and interfacial bonding retention rate of the embodiment both reach over 89% (95.8%-96.2% in embodiment 3). Due to the lack of core structure / process (no graded layer, no doping, process substitution), the retention rate of the comparative example is less than 75%, and the interlayer is prone to peeling and cracking. This fully demonstrates the reliability and advancement of this technical solution under automotive-grade conditions.

[0071] According to the embodiments of this application, a stainless steel material and its preparation method for an explosion-proof ring for automotive batteries are disclosed. The inner porous electrocatalytic hydrogen elimination layer uses Ce, Gd rare earth elements and transition metal sites as highly efficient catalysts to reduce the activation energy of the hydrogen conversion reaction and eliminate the risk of deflagration from the source. The outer nanocrystalline niobium carbide wear-resistant layer, with its high-hardness and dense structure, resists mechanical wear and erosion to ensure the physical integrity of the valve body. The functional gradient layer added between the stainless steel matrix and the catalyst layer achieves a continuous and smooth transition of chemical composition along the thickness direction, avoids the sharp interface formed by the abrupt change in physical properties between the matrix and the catalyst layer, absorbs and disperses stress under thermal cycling or external force, inhibits crack initiation and propagation, and improves the interfacial bonding force to meet the long-term stability requirements of automotive-grade products. The nanocrystalline structure, with the help of the Hall-Page effect, hinders dislocation movement through a large number of grain boundaries. To enhance hardness and strength, the doping of Ti, V, and Cr elements forms a solid solution, resulting in a solid solution strengthening effect that synergistically optimizes overall mechanical properties and thermal stability, preventing brittle spalling. Ce and Gd rare earth elements can adjust the electronic state density of active centers, and a three-dimensional interconnected mesoporous-macroporous network with a porosity of 20%-60% is constructed, increasing the exposure of active sites and providing channels for gas-phase mass transfer, reducing mass transfer limitations and ensuring efficient reactions. The preparation employs an inner-catalyst and outer-wear-resistant layered design, avoiding thermal damage and contamination of the catalytic layer by the wear-resistant layer deposition. Magnetron sputtering technology is used to prepare functionally graded layers in situ, achieving atomic-scale compositional control. Electrochemical deposition is used to uniformly grow catalytic precursors on complex surfaces, combined with subsequent heat treatment to generate the target phase. This integrates the advantages of both deposition technologies, with a clearly defined parameter window facilitating large-scale production and quality control. This system overcomes the technical bottlenecks of traditional explosion-proof ring materials, such as low hydrogen removal efficiency, weak interfacial bonding, insufficient mechanical properties, poor adaptability to extreme conditions, and difficulty in large-scale preparation, improving the material's hydrogen removal performance, structural stability, and durability under operating conditions.

[0072] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

[0073] The present application and its embodiments have been described above. This description is not restrictive, and the actual application is not limited thereto. In conclusion, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of this application, such design should fall within the protection scope of this application.

Claims

1. A stainless steel material for explosion-proof rings in automotive batteries, characterized in that, include: Stainless steel base; A functional gradient layer is incorporated between the stainless steel substrate and the porous electrocatalytic hydrogen removal layer; The porous electrocatalytic hydrogen removal layer disposed on the functional gradient layer and facing the inside of the battery; and A transition metal carbide wear-resistant layer is disposed on the outer surface of the stainless steel substrate facing the battery, wherein the transition metal carbide wear-resistant layer is a nanocrystalline niobium carbide layer.

2. The stainless steel material for explosion-proof rings of automotive batteries according to claim 1, characterized in that, The functional gradient layer is a transition layer in which the chemical composition changes continuously along the thickness direction, wherein the contents of iron, chromium and nickel decrease from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

3. The stainless steel material for explosion-proof rings of automotive batteries according to claim 2, characterized in that, In the functionally graded layer, the content of at least one element selected from cerium and gadolinium increases from the stainless steel substrate side to the porous electrocatalytic hydrogen removal layer side.

4. The stainless steel material for explosion-proof rings of automotive batteries according to claim 1, characterized in that, The nano-niobium carbide layer is also doped with at least one of titanium, vanadium and chromium, with a doping amount of 1-10 at.

5. The stainless steel material for explosion-proof rings of automotive batteries according to claim 1, characterized in that, The thickness of the nano-niobium carbide layer is 1-5 μm, the average grain size is less than 100 nm, and its Vickers hardness is not less than 28 GPa.

6. The stainless steel material for explosion-proof rings of automotive batteries according to claim 1, characterized in that, The porous electrocatalytic hydrogen removal layer contains rare earth elements cerium or gadolinium, and has a porosity of 20%-60%.

7. The stainless steel material for explosion-proof rings of automotive batteries according to claim 1, characterized in that, The stainless steel matrix is ​​austenitic stainless steel with a thickness of 0.1 mm to 2.0 mm.

8. A method for preparing a stainless steel material for an explosion-proof ring for automotive batteries as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Cleaning and surface activation pretreatment of the stainless steel substrate; (2) A dual-target co-sputtering method is used to deposit a functional gradient layer on the pretreated stainless steel substrate facing the inner surface of the battery. By continuously adjusting the sputtering power ratio of the two targets during the sputtering process, the content of Fe, Cr and Ni elements in the functional gradient layer decreases from the substrate side to the catalyst layer side, while the content of Ce and Gd elements increases from the substrate side to the catalyst layer side. The dual targets include a stainless steel target and a target material containing rare earth elements. The sputtering temperature is 100-300℃, the working pressure is 0.1-1.0Pa, and the bias voltage is -50 to -200V. (3) A porous electrocatalytic hydrogen elimination layer is prepared on the surface of the functional gradient layer by electrochemical deposition, wherein the deposition voltage is 1-5V and the deposition time is 10-60min; (4) A nanocrystalline niobium carbide wear-resistant layer is deposited on the outer surface of the stainless steel substrate facing the battery by magnetron sputtering. The sputtering temperature is 200-400℃, the sputtering power is 100-300W, the working pressure is 0.2-1.5Pa, and the bias voltage is -100 to -300V.

9. The method for preparing the stainless steel material for the explosion-proof ring of an automotive battery according to claim 8, characterized in that, The electrolyte used in step (3) for electrochemical deposition contains at least one of cerium salt, gadolinium salt, nickel salt, phosphate, sulfide, or nitride precursor.

10. A vehicle battery explosion-proof ring, characterized in that, It is made of stainless steel material as described in any one of claims 1-7 for explosion-proof rings for automotive batteries.

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