Negative electrode sheet, method for manufacturing, and sulfide solid-state battery

Abstract

This invention discloses a negative electrode sheet, its preparation method, and a sulfide solid-state battery. The negative electrode sheet includes a current collector, which comprises a tab blank area for welding tabs and a coating area with an active coating. A complex coating is disposed on the surface of the tab blank area, containing copper-methylbenzotriazole complexes, copper-adenine complexes, copper-tetrahydropyrrole complexes, copper-cycloethylamine complexes, etc. This application utilizes nitrogen-containing heterocyclic compounds to form chemical coordination bonds with the copper surface, constructing a dense complex coating at the molecular level. The chemical coordination protection mechanism replaces the physical isolation mechanism, providing better protection. Furthermore, the complex coating can directly participate in the welding process without removal. The protective layer transforms into flux during the welding stage, reducing the surface energy of the copper foil at the tab, improving welding quality, and achieving dual functions of corrosion prevention and fluxing. Undecomposed complex coatings can continue to protect the current collector.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to a negative electrode sheet, a preparation method thereof, and a sulfide solid-state battery. Background Technology

[0002] Solid-state batteries are considered a core technology for next-generation high-energy-density, high-safety energy storage devices due to their high ionic conductivity, wide electrochemical window, and excellent interfacial contact characteristics. Among them, sulfide solid electrolytes are particularly noteworthy for their superior room-temperature ionic conductivity (up to 10⁻⁶ Ω·cm). - With its high viscosity (≥3 S / cm) and good mechanical ductility, sulfide solid-state batteries have become one of the most promising solid-state electrolyte systems for industrialization. However, the industrialization process of sulfide solid-state batteries faces severe challenges, among which corrosion in the negative electrode tab area is one of the key bottlenecks restricting manufacturing yield and long-term reliability. The wet manufacturing process of sulfide solid-state battery negative electrode sheets typically includes: mixing negative electrode active materials, conductive agents, sulfide solid electrolytes, binders, and solvents to prepare a slurry, then coating it onto the surface of a copper foil current collector, and finally preparing the negative electrode sheet through processes such as drying, curing, and rolling.

[0003] During the coating and drying / curing process described above, the sulfide solid electrolyte releases trace amounts of sulfur-containing active species (such as H2S and polysulfides) under solvent and heating conditions. These corrosive substances diffuse into the tab area and react chemically with the exposed copper foil surface to generate insulating corrosion products such as copper sulfide (Cu2S, CuS). This corrosion phenomenon can cause the following problems: First, the corrosion products increase the contact resistance in the tab area, leading to an abnormal increase in the cell's internal resistance, causing localized heat generation and accelerating battery performance degradation. Second, the formation of corrosion products damages the mechanical integrity of the copper foil, causing the tabs to experience incomplete welding, damage, or even breakage during ultrasonic welding, severely affecting the cell's assembly yield. Third, corrosion may continue to spread during battery testing, leading to the failure of the electrical connection between the tabs and the current collector, causing early battery failure.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a negative electrode sheet, a preparation method, and a sulfide solid-state battery, which solves the problem of sulfide corrosion in the electrode area during the manufacturing process of sulfide solid-state batteries while ensuring that the tabs can be firmly welded.

[0006] This invention is implemented as follows: In a first aspect, the present invention provides a negative electrode sheet comprising a current collector, the current collector comprising a tab blank area for welding tabs and a coating area disposed on one side of the tab blank area and coated with an active coating, the surface of the tab blank area being provided with a complex coating, the complex coating comprising at least one of a copper-methylbenzotriazole complex, a copper-adenine complex, a copper-tetrahydropyrrole complex, a copper-cycloethylamine complex, a copper-methylbenzotriazole derivative complex, a copper-adenine derivative complex, a copper-tetrahydropyrrole derivative complex, and a copper-cycloethylamine derivative complex.

[0007] In an optional embodiment, the area of ​​the coating area is 80-90% of the area of ​​the tab blank area.

[0008] In an optional embodiment, the thickness of the complex coating is 10 nm to 200 nm.

[0009] In an optional embodiment, the complex coating includes a copper-methylbenzotriazole complex and a copper-adenine complex; And / or, both sides of the current collector are provided with a coating area and a tab blank area.

[0010] In an optional embodiment, the mass ratio of methylbenzotriazole ligand to adenine ligand in the complex coating is (0.1-20):3.

[0011] Secondly, the present invention provides a method for preparing the negative electrode sheet according to any one of the foregoing embodiments, comprising: A corrosion inhibitor solution is applied to the blank area of ​​the tab of the current collector with an active coating, followed by baking to form the complex coating. The current collector coated with the complex is dried and rolled to obtain the negative electrode sheet.

[0012] In an optional embodiment, the solute in the corrosion inhibitor solution is selected from at least one of methylbenzotriazole and its derivatives, tetrahydropyrrole and its derivatives, cycloethylamine and its derivatives, and adenine and its derivatives; And / or, the solvent in the corrosion inhibitor solution is selected from anhydrous ethanol.

[0013] In an optional embodiment, the mass fraction of the solute in the corrosion-inhibiting solution is 0.01% to 10%.

[0014] In an optional embodiment, the baking temperature is 30-60°C; And / or, the application rate of the corrosion inhibitor solution is less than 0.8 m / min.

[0015] Thirdly, the present invention provides a sulfide solid-state battery, including the negative electrode sheet described in any of the foregoing embodiments.

[0016] The present invention has the following beneficial effects: This application utilizes nitrogen-containing heterocyclic compounds to form chemical coordination bonds with the copper surface, constructing a dense complex coating at the molecular level. This chemical coordination protection mechanism replaces the physical isolation mechanism, resulting in superior protection. Furthermore, the complex coating can directly participate in the welding process without removal. During the welding stage, the protective layer transforms into flux, reducing the surface energy of the copper foil at the electrode tabs, improving welding quality, and achieving both corrosion protection and fluxing functions. Undecomposed complex coatings can continue to protect the current collector. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A top view of the negative electrode sheet provided in Example 1; Figure 2 A cross-sectional view of the negative electrode sheet provided in Example 1; Figure 3 The first 0.1C charge-discharge curve (top) and the discharge retention rate at different rates (bottom); Figure 4 XPS spectrum of copper element after coating copper foil with corrosion inhibitor solution.

[0019] Illustration: 1-Current collector; 2-Taper blank area; 3-Coating area. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0021] The applicant discovered that during the preparation of sulfide solid electrolytes (such as Li3PS4, Li6PS5Cl, etc.), trace amounts of sulfur-based active species are released or come into contact with the copper current collector, reacting chemically to form copper sulfides (Cu2S, CuS, etc.). This leads to insulation of the copper foil surface, resulting in poor soldering or detachment during electrode welding; a sharp increase in contact resistance; abnormal internal resistance of the battery; and continuous corrosion expansion during long-term cycling, causing failure. To address the problem of sulfide corrosion in the electrode area during the manufacturing process of sulfide solid batteries, one approach is to optimize the slurry formulation and drying process to reduce the generation of corrosive gases; another is to set a physical isolation layer in the electrode area to prevent corrosive gases from contacting the copper foil. However, the former cannot fundamentally eliminate the chemical instability of sulfide electrolytes, while the latter usually requires an additional step of removing the isolation layer before welding, increasing process complexity. The applicant's research found that, taking the setting of a polymer protective layer in the electrode area to form a physical barrier as an example, although the polymer protective layer can prevent corrosive gases from contacting the copper foil, it depends on the integrity and density of the protective layer. Once the polymer protective layer has pinholes or defects, corrosion can still occur. Late-stage corrosion can continue to expand during battery use, leading to the failure of the electrical connection between the tab and the current collector, and causing early battery failure. These problems inevitably reduce production yield and efficiency, increase battery costs, and hinder large-scale promotion and applicability. Therefore, developing a tab protection method that can effectively protect the tab area from sulfide corrosion during manufacturing without adding additional removal steps or affecting subsequent welding processes is of significant practical importance for promoting the industrialization of sulfide solid-state batteries.

[0022] The present invention also provides a negative electrode sheet, such as... Figure 1-2 As shown, it includes a current collector 1, which includes a tab blank area 2 for welding tabs and a coating area 3 with an active coating disposed on one side of the tab blank area. The surface of the tab blank area 2 is provided with a complex coating, which contains at least one of copper-methylbenzotriazole complex, copper-adenine complex, copper-tetrahydropyrrole complex, copper-cycloethylamine complex, copper-methylbenzotriazole derivative complex, copper-adenine derivative complex, copper-tetrahydropyrrole derivative complex, and copper-cycloethylamine derivative complex.

[0023] The complex coating is chemically inert, effectively preventing sulfide corrosion of the copper foil. Furthermore, during subsequent tab welding, the high welding temperature (≥200℃) causes thermal decomposition of the complexes in the coating. The decomposition products reduce and remove trace amounts of residual oxides on the copper surface, exposing a fresh, highly reactive copper surface, thus significantly improving the wettability of the nickel metal on the tabs to the copper foil. Simultaneously, the controlled decomposition of the complex coating can regulate and optimize the growth morphology of intermetallic compounds at the weld interface, ultimately enhancing weld strength.

[0024] This application utilizes nitrogen-containing heterocyclic compounds to form chemical coordination bonds with the copper surface, constructing a dense complex coating at the molecular level. This chemical coordination protection mechanism replaces the physical isolation mechanism, providing better protection than physical coating. Furthermore, the complex coating can directly participate in the welding process without removal; the protective layer transforms into flux during welding, reducing the surface energy of the copper foil at the electrode tab, improving welding quality, and achieving dual functions of corrosion protection and fluxing, while reducing material costs. Additionally, the complex coating is only applied to the electrode tab blank area 2 used for welding the electrode tab, avoiding the impact of applying the complex coating to the entire surface of the current collector 1 on the interface between the active material and the current collector 1. The amount of protective agent used is small, and costs are controllable. Undecomposed complex coatings can continue to protect the current collector 1. In particular, the adenine in the complex coating can form a dense film on the copper surface, effectively inhibiting copper corrosion, while also being highly environmentally friendly due to its biological origin.

[0025] It should be noted that a certain gap, such as 1 mm or 2 mm, can be set between the coating area 3 on the surface of the current collector 1 and the blank area 2 of the tab, in order to avoid contamination of the active coating during the preparation of the complex coating, thereby affecting the electrochemical performance of the battery.

[0026] In an optional embodiment, the area of ​​the coating area is 80-90% of the area of ​​the tab blank area, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90%.

[0027] In an optional embodiment, the thickness of the complex coating is 10nm-200nm, such as 10nm, 31nm, 52nm, 73nm, 94nm, 115nm, 136nm, 157nm, 178nm, or 200nm. The complex coating has a certain thickness to cover the tab blank area 2 and achieve protection of the complex coating.

[0028] It should be noted that the widths of the tab blank area and the coating area in this application refer to the dimensions along the direction from the tab blank area to the coating area.

[0029] In an optional embodiment, the complex coating includes a copper-methylbenzotriazole complex and a copper-adenine complex; the applicant has found through experiments that when the complex coating includes a copper-methylbenzotriazole complex and a copper-adenine complex, it is more beneficial to improve the welding strength of the tab in the tab blank area 2.

[0030] In an optional embodiment, a coating area 3 and a tab blank area 2 are provided on both sides of the current collector 1.

[0031] In an optional embodiment, the mass ratio of methylbenzotriazole ligand to adenine ligand in the complex coating is (0.1-20):3, for example 0.1:3, 2.2:3, 4.3:3, 6.4:3, 8.5:3, 10.6:3, 12.7:3, 14.8:3, 16.9:3, 20:3, which is more conducive to improving the welding strength of the tab in the tab blank area 2.

[0032] The present invention also provides a method for preparing the negative electrode sheet according to any one of the foregoing embodiments, comprising: A corrosion inhibitor solution is applied to the tab blank area 2 of the current collector 1, which is provided with an active coating, and then baked to form the complex coating. The current collector 1, which has a complex coating, is dried and rolled to obtain the negative electrode sheet.

[0033] The blank area 2 of the negative electrode sheet is often corroded by sulfide electrolyte, affecting the mechanical and drying properties of the tab. Therefore, this application coats the blank area 2 of the tab with a slow-release solution after coating the negative electrode slurry. The corrosion-inhibiting solution forms a complex coating with the copper surface, constructing a dense protective film at the molecular level.

[0034] In an optional embodiment, the solute in the corrosion inhibitor solution is selected from at least one of methylbenzotriazole and its derivatives, tetrahydropyrrole and its derivatives, cycloethylamine and its derivatives, and adenine and its derivatives. The solute in the corrosion inhibitor solution reacts with the copper current collector 1 to form corresponding complexes. For example, methylbenzotriazole, tetrahydropyrrole, cycloethylamine, and adenine react with copper to form copper-methylbenzotriazole complexes, copper-adenine complexes, copper-tetrahydropyrrole complexes, and copper-cycloethylamine complexes, respectively. Exemplary derivatives include 2,2'-[[(5-methyl-1H-benzotriazole-1-yl)methyl]imino]diethanol, 5-benzylmethyl-benzotriazole, 6-benzylaminopurine, etc.

[0035] In an optional embodiment, the solvent in the corrosion inhibitor solution is selected from anhydrous ethanol, which can dissolve the solute while being easy to remove.

[0036] In an optional embodiment, the mass fraction of the solute in the corrosion inhibitor solution is 0.01% to 10%, for example, 0.01%, 1.11%, 2.21%, 3.31%, 4.41%, 5.51%, 6.61%, 7.71%, 8.81%, or 10%. If the mass fraction of the solute in the corrosion inhibitor solution is too high, it cannot fully react with the copper on the surface of the current collector 1 to form a dense complex coating, which will lead to a decrease in the welding strength of the tab in the tab blank area 2. However, if the mass fraction of the solute is too low, it will not be enough to form a continuous and uniform complex coating, which will also lead to a decrease in the welding strength of the tab in the tab blank area 2.

[0037] In an optional embodiment, the baking temperature is 30-60℃, such as 30℃, 33℃, 36℃, 39℃, 42℃, 45℃, 48℃, 51℃, 54℃, 57℃, and 60℃. Since the complex in the complex coating has low thermal stability, if the baking temperature is too high, the complex in the complex coating will decompose, thereby losing its protective effect on the tab blank area 2. If the temperature is too low, the solvent cannot be completely removed during the baking process.

[0038] In an optional embodiment, the coating speed of the corrosion inhibitor solution is less than 0.8 m / min, for example, 0.1 m / min, 0.18 m / min, 0.26 m / min, 0.34 m / min, 0.42 m / min, 0.5 m / min, 0.58 m / min, 0.66 m / min, 0.74 m / min, or 0.8 m / min, to avoid the solvent from being insufficiently removed before proceeding to the next process due to excessive speed. It should be noted that, provided that the solvent can be sufficiently removed, the coating speed should be as fast as possible to improve production efficiency.

[0039] The present invention also provides a sulfide solid-state battery, including the negative electrode sheet described in any of the foregoing embodiments.

[0040] It should be noted that the negative electrode sheet of this application can be used in various sulfide solid-state batteries. For example, a sulfide solid-state battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode active material can be a high-nickel ternary NCM / NCA or a lithium-rich manganese-based oxide; the negative electrode active material can be a traditional graphite, silicon-carbon, or lithium metal negative electrode; and the sulfide solid-state electrolyte can be Li3PS4 or LGPS (Li 10 GeP2S 12 ), Li6PS5Cl, etc.

[0041] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0042] Example 1 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery, specifically including the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0043] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0044] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.012%, and the mass fraction of methylbenzotriazole is 0.3%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0045] Example 2 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the mass percentage of adenine in the corrosion inhibition solution is 0.01%, and the mass percentage of methylbenzotriazole is 0.2%. The specific steps include: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0046] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0047] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.01%, and the mass fraction of methylbenzotriazole is 0.2%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0048] Example 3 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the mass percentage of adenine in the corrosion inhibition solution is 0.036%, and the mass percentage of methylbenzotriazole is 0.9%. The specific steps include: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0049] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0050] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.036%, and the mass fraction of methylbenzotriazole is 0.9%. Subsequent spraying can then be performed. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, then roll and die-cut to obtain the negative electrode sheet.

[0051] Example 4 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Embodiment 1 is that the coating speed of the corrosion inhibitor solution is 0.6 m / min. The specific steps include: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0052] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0053] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.012%, and the mass fraction of methylbenzotriazole is 0.3%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.6 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0054] Example 5 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Embodiment 1 is that the baking temperature in step 3 is 40°C, and the method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0055] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0056] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.012%, and the mass fraction of methylbenzotriazole is 0.3%. Then, subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 40℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, then roll and die-cut to obtain the negative electrode sheet.

[0057] Example 6 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the mass percentage of adenine in the corrosion inhibition solution is 2%, and the mass percentage of methylbenzotriazole is 0.3%. The method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0058] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0059] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 2%, and the mass fraction of methylbenzotriazole is 0.3%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0060] Example 7 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the mass percentage of adenine in the corrosion inhibition solution is 2.5%, and the mass percentage of methylbenzotriazole is 2.5%. The method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0061] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0062] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 2.5%, and the mass fraction of methylbenzotriazole is 2.5%. Then, subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, then roll and die-cut to obtain the negative electrode sheet.

[0063] Example 8 This embodiment provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Embodiment 1 is that the mass percentage of adenine in the corrosion inhibition solution is 5%, and the mass percentage of methylbenzotriazole is 5%. The method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0064] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0065] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 5%, and the mass fraction of methylbenzotriazole is 5%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0066] Example 9 This comparative example provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the mass ratio of adenine in the corrosion inhibition solution is 5% and the mass ratio of methylbenzotriazole is 1%. The method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0067] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0068] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 5%, and the mass fraction of methylbenzotriazole is 1%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, the coating speed is 0.8 m / min, and after double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0069] Example 10 This comparative example provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the coating speed of the corrosion inhibitor solution is 1.2 m / min, and the method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0070] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0071] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.012%, and the mass fraction of methylbenzotriazole is 0.3%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 1.2 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0072] Example 11 This comparative example provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the baking temperature in step 3 is 60°C, and the method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0073] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0074] Step 3: Add adenine to 300 mL of anhydrous ethanol and stir for 5-10 minutes until completely dissolved and the solution is slightly turbid. Then add methylbenzotriazole and continue stirring until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.012%, and the mass fraction of methylbenzotriazole is 0.3%. Then, the subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 60℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0075] Example 12 This comparative example provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that the mass ratio of adenine in the corrosion inhibition solution is 0.012%, and methylbenzotriazole is not added. The specific steps include: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0076] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0077] Step 3: Add adenine to 300 mL of anhydrous ethanol, stir for 5-10 min until completely dissolved, and let stand for 2 min to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0.012%, and the mass fraction of methylbenzotriazole is 0. Then, subsequent spraying can be performed. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll, bake at 50℃, and coat at a speed of 0.8 m / min. After double-sided coating, place in a 60℃ oven for one day, then roll and die-cut to obtain the negative electrode sheet.

[0078] Example 13 This comparative example provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that adenine is not added to the corrosion inhibition solution, and the mass ratio of methylbenzotriazole is 0.3%. The method specifically includes the following steps: Step 1: Weigh the negative electrode active material SiC, solid electrolyte Li6PS5Cl, conductive agent vapor-grown carbon fiber, and binder nitrile rubber NBR in a mass ratio of 62.5:33.5:2:2 to prepare the negative electrode active slurry. Use anisole as a solvent to adjust the solid content to 45wt%. Use a THINKY homogenizer to stir at 1500rpm for 30min to obtain the negative electrode active slurry.

[0079] Step 2: Apply the negative electrode active slurry obtained in Step 1 using a coating machine at a concentration of 4.5 mg / cm³. 2 The areal density is applied to coating area 3, and the baking temperature is 65℃ with a coating speed of 0.8m / min. After double-sided coating is completed, the electrode roll is removed for later use.

[0080] Step 3: Add methylbenzotriazole to 300 mL of anhydrous ethanol and stir until the solution is clear. Let it stand for 2 minutes to obtain the corrosion inhibitor solution. The mass fraction of adenine in the corrosion inhibitor solution is 0, and the mass fraction of methylbenzotriazole is 0.3%. Then, subsequent spraying can be carried out. Coat the corrosion inhibitor solution onto the tab blank area 2 of the negative electrode roll. The baking temperature is 50℃, and the coating speed is 0.8 m / min. After double-sided coating, place it in a 60℃ oven for one day, and then roll and die-cut to obtain the negative electrode sheet.

[0081] Comparative Example 1 This comparative example provides a method for preparing the negative electrode sheet of a sulfide solid-state battery. The main difference from Example 1 is that adenine and methylbenzotriazole were not added to the corrosion inhibition solution.

[0082] Experimental Example 1 After sealing and storing all negative electrode sheets obtained from the above embodiments and comparative examples for 24 hours to ensure sufficient deterioration and corrosion conditions, the reserved tab area was then cut. The copper foil in the tab area was cut out separately, with the specifications being long strips of copper foil 10cm in length and 2cm in width. Seven strips of copper foil were overlapped and the tabs were welded using an ultrasonic welding machine. The welding process parameters included: delay time: 0.05s; welding energy: 2J; cooling time: 0.15s; vibration drop time: 0.1s; amplitude 30%; air pressure 0.2MPa. Nickel-plated copper tabs were selected. Then, a 180-degree horizontal tensile test was performed using a tensile testing machine to measure the maximum tensile force between the tab and the copper foil (the tensile force at the moment of separation between the tab and the copper foil). The test results are shown in Table 1.

[0083] Table 1. Electrode Pull Force Tests of Examples and Comparative Examples

[0084] As can be seen from Examples 1-8, when the total solute mass ratio is within a suitable mass ratio, the coating speed does not exceed 0.8 m / min, and the baking temperature does not exceed 60°C, the solute can fully complex with the copper foil during the coating process. Under the catalysis of copper ions, chemical coordination can be achieved in a short reaction time, thereby forming a corrosion-resistant protective layer. Macroscopically, the tabs and copper foil can be welded normally, and the tab pull is high.

[0085] A comparison of the tensile strength results in Example 9 and Example 1 reveals that when the total solute mass percentage is too high, the dissolution process is poor, resulting in poor subsequent chemical coordination effect. This leads to an incomplete formation of the protective coating, resulting in poor subsequent welding between the tab and the copper foil area, leading to a lower tab tensile strength.

[0086] A comparison of the tensile strength results of Example 10 and Example 1 reveals that when the coating speed is too fast, the solute does not fully complex with the copper foil before baking is completed, resulting in a non-dense protective coating. Consequently, the subsequent welding between the tab and the copper foil area is not tight, leading to a lower tab tensile strength.

[0087] A comparison of the tensile strength results in Example 11 and Example 1 reveals that when the coating baking temperature is too high, the solute may decompose due to high temperature, resulting in insufficient protective layer formation. Consequently, the subsequent welding between the tab and the copper foil area is not tight, leading to lower tab tensile strength.

[0088] As can be seen from Examples 12 and 13, the solute can be used alone, but the overall effect is worse than when used in combination.

[0089] As can be seen from Comparative Example 1, without the coating of corrosion inhibitor solution, the tab pull is very low and almost impossible to weld.

[0090] Experimental Example 2 The negative electrode sheets obtained in Example 1 and Comparative Example 1 were subjected to 2Ah soft-pack laminated cell packaging tests. Capacity and rate performance were tested under a pressure of 20 MPa and a temperature of 45°C. The test results are as follows: Figure 3 As shown, in Example 1, the corrosion inhibitor solution was used to treat the blank area 2 of the electrode tab for corrosion protection, which had almost no effect on the capacity and rate capability of the battery cell, and was comparable to Comparative Example 1.

[0091] Experimental Example 3 XPS testing was performed on the copper foil in the tab region of the negative electrode sheet prepared in Example 1. The test results are as follows: Figure 4 As shown, Figure 4 The presence of monovalent copper in the sample confirms the existence of the complex.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A negative electrode sheet comprising a current collector, characterized by, The current collector includes a tab blank area for welding tabs and a coating area with an active coating on one side of the tab blank area. The surface of the tab blank area is provided with a complex coating, which contains at least one of the following: copper-methylbenzotriazole complex, copper-adenine complex, copper-tetrahydropyrrole complex, copper-cycloethylamine complex, copper-methylbenzotriazole derivative complex, copper-adenine derivative complex, copper-tetrahydropyrrole derivative complex, and copper-cycloethylamine derivative complex.

2. The negative electrode sheet according to claim 1, characterized by, The area of ​​the coating region is 80-90% of the area of ​​the blank area of ​​the tab.

3. The negative electrode sheet according to claim 1, wherein The thickness of the complex coating is 10nm-200nm.

4. The negative electrode sheet according to claim 1, wherein The complex coating includes a copper-methylbenzotriazole complex and a copper-adenine complex; And / or, both sides of the current collector are provided with a coating area and a tab blank area.

5. The negative electrode sheet according to claim 4, characterized by In the complex coating, the mass ratio of methylbenzotriazole ligand to adenine ligand is (0.1-20):

3.

6. A method for producing the negative electrode sheet according to any one of claims 1 to 5, characterized by, include: A corrosion inhibitor solution is applied to the blank area of ​​the tab of the current collector with an active coating, followed by baking to form the complex coating. The current collector coated with the complex is dried and rolled to obtain the negative electrode sheet.

7. The method according to claim 6, wherein The solute in the corrosion inhibitor solution is selected from at least one of methylbenzotriazole and its derivatives, tetrahydropyrrole and its derivatives, cycloethylamine and its derivatives, and adenine and its derivatives. And / or, the solvent in the corrosion inhibitor solution is selected from anhydrous ethanol.

8. The method for preparing the negative electrode sheet according to claim 6, characterized in that, The mass fraction of the solute in the corrosion-inhibiting solution is 0.01% to 10%.

9. The method according to claim 6, wherein The baking temperature is 30-60℃; And / or, the application rate of the corrosion inhibitor solution is less than 0.8 m / min.

10. A sulfide solid-state battery, characterized by, Includes the negative electrode sheet as described in any one of claims 1-5.

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