Electrolyte and preparation method of electrolytic copper foil for solid-state battery

Abstract

The invention relates to the field of solid-state batteries, in particular to an electrolyte and a preparation method of an electrolytic copper foil for a solid-state battery. The electrolyte comprises the following components by concentration: 80 to 100 g / L of Cu < 2 + >, 105 to 120 g / L of sulfuric acid, 5 to 25 g / L of gelatin, 10 to 40 g / L of isothiourea propanesulfonic acid inner salt, 3 to 15 g / L of diethyl propyne amine, 5 to 35 g / L of (R)-4-benzyl thiazoline-2-thioketone, 10 to 30 mg / L of Cl <->, and the balance of water. By adopting a specific formula and process, the tensile strength of the prepared copper foil reaches 400-500MPa, the elongation is greater than or equal to 5.0%, the roughness Ra is greater than or equal to 0.45 mu m, the roughness Rz is greater than or equal to 2.50 mu m, and the specific surface area is greater than 0.36 m < 2 > / g; the problems that in the prior art, a copper foil is prone to deformation and breakage and high in interface impedance are solved, and therefore the charge-discharge efficiency and the cycle performance of the solid-state battery are improved.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, specifically to an electrolyte and a method for preparing electrolytic copper foil for solid-state batteries. Background Technology

[0002] Solid-state batteries, as the next-generation new energy storage technology, rely on breakthroughs in the performance of key materials for their high energy density and safety advantages. Among these, optimizing the performance of the negative electrode current collector is one of the core challenges. Compared to traditional liquid batteries, solid-state batteries using lithium metal or high-capacity silicon-based negative electrodes face problems such as high risk of lithium dendrite puncture, high interfacial impedance, and significant volume expansion, placing stringent requirements on the mechanical strength, interfacial adhesion, and structural stability of the current collector. Electrolytic copper foil, as the mainstream negative electrode current collector, directly affects the cycle life and safety performance of solid-state batteries. Currently, increasing the mechanical strength of copper foil often leads to a decrease in elongation, while increasing surface roughness to improve interfacial adhesion easily induces dendrite growth. Furthermore, traditional copper foil, due to its insufficient specific surface area, suffers from poor interfacial contact with the solid electrolyte, resulting in increased ion transport resistance and limiting the battery's rate performance.

[0003] Chinese invention patent CN110016697B discloses a method for preparing high-temperature, high-elongation electrolytic copper foil. Through the compounding of additives such as polyethyleneimine derivatives and sodium thiopropane sulfonate, the method achieves an elongation of ≥5.0% at both room temperature and 60℃, improving the material's fatigue resistance and effectively solving the cracking problem in the rolling process of power batteries. However, it does not address the interface optimization requirements specific to solid-state batteries; its surface roughness Ra ≤ 0.3μm, and it does not explore tensile strength and specific surface area, thus failing to meet the requirements for solid-state electrolytes. Summary of the Invention

[0004] The first aspect of this invention provides an electrolyte comprising components of the following concentrations: Cu 2+ 80-100 g / L, sulfuric acid 105-120 g / L, gelatin 5-25 g / L, isothiourea propanesulfonic acid inner salt 10-40 g / L, diethylpropynylamine 3-15 g / L, (R)-4-benzylthiazoline-2-thione 5-35 g / L, Cl - 10-30 mg / L, add water to make up the balance.

[0005] The electrolyte system in this application, composed of gelatin, isothiourea propanesulfonic acid inner salt, diethylpropynylamine, and (R)-4-benzylthiazoline-2-thione, achieves high tensile strength (400-500 MPa) and high elongation (≥5.0%) in copper foil. Gelatin, as an organic macromolecular additive, adsorbs onto the copper deposition surface, hindering disordered grain growth; isothiourea propanesulfonic acid inner salt and diethylpropynylamine regulate Cu through charge interaction. 2+The reduction rate promotes grain refinement; (R)-4-benzylthiazoline-2-thione may induce the oriented arrangement of copper atoms through chiral sites, reducing grain boundary defects.

[0006] The second aspect of the present invention provides a method for preparing electrolytic copper foil for solid-state batteries, comprising the following steps: electrolyzing an electrolyte to form a foil, thereby obtaining a copper foil semi-finished product; and simultaneously roughening and curing the copper foil semi-finished product on both sides to obtain electrolytic copper foil for solid-state batteries.

[0007] The electrolyte temperature is 50-60℃; the electrolyte flow rate is 50-65m³ / h. 3 / h; the current density of the electrolyte is 3500-6000 A / m 2 .

[0008] This application utilizes specific electrolyte temperatures (50-60℃) and flow rates (50-65m³ / h). 3 / h) and current density (3500-6000A / m 2 Setting the appropriate parameters can improve mass transfer efficiency and deposition uniformity. A liquid temperature of 50-60°C can balance Cu. 2+ Diffusion rate and additive stability are considered to avoid uneven deposition and decreased elongation caused by low temperatures; 50-65m 3 A flow rate of / h ensures uniform electrolyte concentration and prevents localized Cu concentrations. 2+ Depletion leads to structural loosening; while 3500-6000 A / m 2 The optimal current density ensures a high deposition rate while avoiding insufficient tensile strength caused by low current density. These three factors work synergistically to create a dense copper foil deposition layer, reducing porosity and stress concentration, thereby improving overall mechanical properties.

[0009] During the roughening process, Cu 2+ The concentration is 18-30 g / L; the sulfuric acid concentration during the roughening process is 115-135 g / L; the current density during the roughening process is 1500-3000 A / m. 2 .

[0010] This application employs a specific dual-sided simultaneous roughening process to precisely control the surface morphology and optimize interfacial contact. During the roughening process, 18-30 g / L of Cu... 2+ Concentration, sulfuric acid concentration of 115-135 g / L and 1500-3000 A / m 2 By controlling the current density and the secondary deposition rate of copper on the foil surface, a uniformly distributed micron-sized protrusion structure is formed, resulting in a copper foil surface roughness Ra≥0.45μm, Rz≥2.00μm, and a specific surface area of ​​0.368m². 2 / g. This may be achieved by increasing the surface roughness structure, expanding the contact area with the solid electrolyte, and reducing the interfacial impedance; at the same time, a reasonable roughness range can suppress the risk of lithium dendrite puncture, resolving the contradiction between the interfacial bonding force and dendrite growth of traditional copper foil.

[0011] Cu during the curing process 2+ The concentration is 40-60 g / L, and the sulfuric acid concentration is 90-115 g / L; the current density during the curing process is 800-1500 A / m. 2 .

[0012] This application utilizes a specific curing process to enhance the roughened layer structure, balancing copper foil stability and interfacial performance. This likely involves depositing a dense copper layer on the roughened, raised surface. This dense layer retains the high specific surface area resulting from the roughening process while simultaneously filling the micropores of the roughened layer through slow deposition at a lower current density, thus enhancing overall structural stability. Specific curing parameters enable the copper foil to maintain a tensile strength exceeding 400 MPa even with high roughness, achieving a synergistic optimization of interfacial adhesion and mechanical stability.

[0013] Beneficial effects 1. The electrolyte of this application contains a compound system of gelatin, isothiourea propanesulfonic acid inner salt, diethylpropynylamine and (R)-4-benzylthiazoline-2-thione, which can achieve high tensile strength (400-500MPa) and high elongation (≥5.0%) of copper foil.

[0014] 2. This application utilizes specific electrolyte temperatures (50-60℃) and flow rates (50-65m³ / h). 3 / h) and current density (3500-6000A / m 2 The setting of ) can promote mass transfer efficiency and deposition uniformity.

[0015] 3. This application precisely controls the surface morphology and optimizes the interfacial contact through a specific double-sided synchronous roughening process, resulting in a copper foil with a specific surface area of ​​0.368 μm². 2 / g.

[0016] 4. This application strengthens the roughened layer structure through a specific curing process, achieving synergistic optimization of interfacial bonding force and mechanical stability while taking into account both copper foil stability and interfacial performance.

[0017] 5. The aluminum foil prepared in this application not only ensures high tensile strength but also has high bonding strength, which can meet the performance requirements of solid-state batteries. Attached Figure Description

[0018] Figure 1 This is an electron microscope image of the cross-section of the electrolytic copper foil prepared in Example 9. Detailed Implementation

[0019] Example 1 An electrolyte comprising the following components at the following concentrations: Cu 2+ 90 g / L, sulfuric acid 113 g / L, gelatin 15 g / L, isothiourea propanesulfonic acid inner salt 25 g / L, diethylpropynylamine 9 g / L, (R)-4-benzylthiazoline-2-thione 20 g / L, Cl - 20 mg / L, add water to make up the balance.

[0020] The gelatin was purchased from Xilong Chemical, product number: 1410010201700.

[0021] The preparation of the electrolyte comprises the following steps: placing copper wire in a copper dissolving vessel, adding sulfuric acid and water, heating to dissolve, filtering to remove impurities, and then mixing with glue, isothiourea propanesulfonic acid inner salt, diethylpropynylamine, (R)-4-benzylthiazoline-2-thione and Cl. - The (hydrochloric acid) is thoroughly mixed to obtain the electrolyte.

[0022] A method for preparing electrolytic copper foil for solid-state batteries includes the following steps: electrolytic foil preparation using an electrolyte to obtain a copper foil semi-finished product; and simultaneous double-sided roughening and curing of the copper foil semi-finished product to obtain the electrolytic copper foil for solid-state batteries, as shown in the cross-sectional electron microscope image. Figure 1 As shown.

[0023] The electrolyte temperature is 55°C.

[0024] The flow rate of the electrolyte is 58m³. 3 / h.

[0025] The current density of the electrolyte is 4700 A / m. 2 .

[0026] During the roughening process, Cu 2+ The concentration is 24 g / L.

[0027] The sulfuric acid concentration during the roughening process is 125 g / L.

[0028] The current density during the roughening process is 2200 A / m 2 .

[0029] Cu during the curing process 2+ The concentration is 50 g / L.

[0030] The sulfuric acid concentration during the curing process is 103 g / L.

[0031] The current density during the curing process is 1200 A / m. 2 .

[0032] Example 2 The specific implementation method is the same as in Example 1; the difference is that the electrolyte temperature is 60℃ and the current density of the electrolyte is 3500A / m. 2 .

[0033] Example 3 The specific implementation method is the same as in Example 1; the difference is that the Cu in the electrolyte... 2+ 80 g / L; the flow rate of the electrolyte is 65 m³ / L. 3 / h.

[0034] Example 4 The specific implementation method is the same as in Example 1; the difference is that the sulfuric acid in the electrolyte is 105 g / L; and the current density of the electrolyte is 6000 A / m. 2 .

[0035] Example 5 The specific implementation method is the same as in Example 1; the difference is that the Cu in the electrolyte... 2+ 100g / L, gelatin 5g / L.

[0036] Example 6 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains 120g / L sulfuric acid and Cl. - 10 mg / L.

[0037] Example 7 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains 25 g / L gelatin and 10 g / L isothiourea propanesulfonic acid inner salt.

[0038] Example 8 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains Cl - 30 mg / L, diethylpropyne 3 g / L.

[0039] Example 9 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains 40 g / L of isothiourea propanesulfonic acid inner salt and 5 g / L of (R)-4-benzylthiazoline-2-thione.

[0040] Example 10 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains 15 g / L of diethylpropynylamine. During the roughening process, Cu 2+ The concentration is 18 g / L.

[0041] Example 11 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains 35 g / L of (R)-4-benzylthiazoline-2-thione and the sulfuric acid concentration during the roughening process is 115 g / L.

[0042] Example 12 The specific implementation method is the same as in Example 1; the difference is that, during the roughening process, Cu... 2+ The concentration was 30 g / L, and the current density during the roughening process was 1500 A / m. 2 .

[0043] Example 13 The specific implementation method is the same as in Example 1; the difference is that the sulfuric acid concentration during the roughening process is 135 g / L; and the Cu concentration during the curing process is... 2+ The concentration is 40 g / L.

[0044] Example 14 The specific implementation method is the same as in Example 1; the difference is that the current density during the roughening process is 3000 A / m. 2 The sulfuric acid concentration during the curing process is 90 g / L.

[0045] Example 15 The specific implementation method is the same as in Example 1; the difference is that, during the curing process, Cu... 2+ The concentration is 60 g / L; the current density during the curing process is 800 A / m. 2 .

[0046] Example 16 The specific implementation method is the same as in Example 1; the difference is that the electrolyte temperature is 50°C and the sulfuric acid concentration during the curing process is 115 g / L.

[0047] Example 17 The specific implementation method is the same as in Example 1; the difference is that the flow rate of the electrolyte is 50m³. 3 / h; the current density during the curing process is 1500A / m 2 .

[0048] Comparative Example 1 The specific implementation method is the same as in Example 1; the difference is that the electrolyte temperature is 45°C.

[0049] Comparative Example 2 The specific implementation method is the same as in Example 1; the difference is that the flow rate of the electrolyte is 45m³. 3 / h.

[0050] Comparative Example 3 The specific implementation method is the same as in Example 1; the difference is that the current density of the electrolyte is 3000 A / m. 2 .

[0051] Comparative Example 4 The specific implementation method is the same as in Example 1; the difference is that the Cu in the electrolyte... 2+ 70g / L.

[0052] Comparative Example 5 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains 100g / L of sulfuric acid.

[0053] Comparative Example 6 The specific implementation method is the same as in Example 1; the difference is that 15g / L of gelatin is not added to the electrolyte.

[0054] Comparative Example 7 The specific implementation method is the same as in Example 1; the difference is that the electrolyte contains Cl - 40 mg / L.

[0055] Comparative Example 8 The specific implementation method is the same as in Example 1; the difference is that isothiourea propanesulfonic acid inner salt is not added to the electrolyte.

[0056] Comparative Example 9 The specific implementation method is the same as in Example 1; the difference is that diethylpropyneamine is not added to the electrolyte.

[0057] Comparative Example 10 The specific implementation method is the same as in Example 1; the difference is that (R)-4-benzylthiazoline-2-thione is not added to the electrolyte.

[0058] Comparative Example 11 The specific implementation method is the same as in Example 1; the difference is that, during the roughening process, Cu... 2+ The concentration is 15 g / L.

[0059] Comparative Example 12 The specific implementation method is the same as in Example 1; the difference is that the sulfuric acid concentration during the roughening process is 100 g / L.

[0060] Comparative Example 13 The specific implementation method is the same as in Example 1; the difference is that the current density during the roughening process is 1000 A / m. 2 .

[0061] Comparative Example 14 The specific implementation method is the same as in Example 1; the difference is that, during the curing process, Cu... 2+ The concentration is 30 g / L.

[0062] Comparative Example 15 The specific implementation method is the same as in Example 1; the difference is that the sulfuric acid concentration during the curing process is 80 g / L.

[0063] Comparative Example 16 The specific implementation method is the same as in Example 1; the difference is that the current density during the curing process is 1000 A / m. 2 .

[0064] Comparative Example 17 The specific implementation method is the same as in Example 1; the difference is that the isothiourea propanesulfonic acid inner salt is replaced with sodium phenyl polydithiopropanesulfonate.

[0065] Comparative Example 18 The specific implementation method is the same as in Example 1; the difference is that diethylpropynylamine is replaced with triethylbenzylammonium chloride.

[0066] Comparative Example 19 The specific implementation method is the same as in Example 1; the difference is that (R)-4-benzylthiazoline-2-thione is replaced with 3-methyltetrahydrothiazoline-2-thione.

[0067] Performance testing methods and data 1. Prepare 6-micron copper foil according to the methods in the examples and comparative examples. Test the tensile strength and elongation of the copper foil according to the test methods in GB / T 29847-2013. The test data are listed in Table 1.

[0068] 2. The copper foil prepared in Example 9 ( Figure 1 The specific surface area of ​​the copper foil in this application was tested using the BET method compared to ordinary copper foil (Jiayuan Technology: 6μm double-sided bright copper foil). The specific surface area of ​​the copper foil in this application was 0.3680±0.0115m². 2 / g, higher than that of ordinary copper foil (0.2360±0.0041m). 2 / g.

[0069] Table 1

[0070] As shown in Table 1, the copper foil prepared in the embodiments of this application has a tensile strength of 400-500 MPa, an elongation of ≥5.0%, a roughness Ra≥0.45 μm, and Rz≥2.50 μm. The copper foil prepared in the comparative examples cannot simultaneously achieve the above properties.

Claims

1. An electrolyte, characterized in that, Components including the following concentrations: Cu 2+ 80-100 g / L, sulfuric acid 105-120 g / L, gelatin 5-25 g / L, isothiourea propanesulfonic acid inner salt 10-40 g / L, diethylpropynylamine 3-15 g / L, (R)-4-benzylthiazoline-2-thione 5-35 g / L, Cl - 10-30 mg / L, add water to make up the balance.

2. A method for preparing electrolytic copper foil for solid-state batteries, characterized in that, The process includes the following steps: electrolyzing the electrolyte described in claim 1 to produce a copper foil semi-finished product; and simultaneously roughening and curing the copper foil semi-finished product on both sides to obtain an electrolytic copper foil for solid-state batteries.

3. The method for preparing electrolytic copper foil for solid-state batteries according to claim 2, characterized in that, The electrolyte temperature is 50-60℃.

4. The method for preparing electrolytic copper foil for solid-state batteries according to claim 2, characterized in that, The flow rate of the electrolyte is 50-65 m³ / h. 3 / h.

5. The method for preparing electrolytic copper foil for solid-state batteries according to claim 2, characterized in that, The current density of the electrolyte is 3500-6000 A / m. 2 .

6. The method for preparing electrolytic copper foil for solid-state batteries according to any one of claims 2-5, characterized in that, During the roughening process, Cu 2+ The concentration is 18-30 g / L.

7. The method for preparing electrolytic copper foil for solid-state batteries according to claim 6, characterized in that, The sulfuric acid concentration during the roughening process is 115-135 g / L.

8. The method for preparing electrolytic copper foil for solid-state batteries according to claim 7, characterized in that, The current density during the roughening process is 1500-3000 A / m 2 .

9. The method for preparing electrolytic copper foil for solid-state batteries according to claim 2 or 8, characterized in that, Cu during the curing process 2+ The concentration is 40-60 g / L, and the sulfuric acid concentration is 90-115 g / L.

10. The method for preparing electrolytic copper foil for solid-state batteries according to claim 9, characterized in that, The current density during the curing process is 800-1500 A / m 2 .

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