Solid-state battery electrode tab, method of making and use thereof

Abstract

The application relates to a solid-state battery electrode pole piece, a preparation method thereof and application, and belongs to the technical field of solid-state batteries. The preparation method of the solid-state battery electrode pole piece comprises the following steps: S1, electrode active material, electrolyte salt, conductive agent and binder are added into water in proportion, mixed uniformly to prepare electrode slurry; S2, the electrode slurry is subjected to spray drying treatment to obtain composite electrode powder; then the composite electrode powder is further subjected to vacuum drying treatment to prepare dehydrated composite electrode powder; S3, the dehydrated composite electrode powder is subjected to fiberization treatment, then is calendered into a film, and finally is hot-pressed to the surface of a current collector to obtain the solid-state battery electrode pole piece. The application can improve the contact area among pole piece composition substances, fully exert the ionic conductive capacity of an electrolyte and the electronic conductive capacity of a conductive agent, and finally improve the rate performance and cycle performance of the solid-state battery.

Description

Technical Field

[0001] This invention relates to a technology in the field of solid-state batteries, specifically a solid-state battery electrode sheet, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of the new energy industry, the demand for new energy batteries, especially new energy lithium batteries, is increasing in the fields of consumer electronics, energy storage, aerospace and electric vehicles. The performance requirements for batteries, such as safety, energy density and power density, are also getting higher and higher. However, traditional liquid batteries are increasingly limited in terms of safety and energy density.

[0003] Solid-state batteries are gaining popularity due to their superior safety, smaller size, lighter weight, and higher energy density. However, solid-state battery electrodes are typically manufactured using dry processes, which, in addition to demanding environmental requirements, also present challenges such as uneven dispersion of the electrolyte, active materials, conductive agents, and binders, as well as small contact areas between the electrolyte, conductive agents, and active materials. These issues affect the ionic conductivity of the electrolyte and the electronic conductivity of the conductive agents, ultimately impacting the power and cycle performance of the solid-state battery.

[0004] The present invention is made to address the aforementioned problems existing in the prior art. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention proposes a solid-state battery electrode sheet, its preparation method, and its application. This invention can increase the contact area between the constituent materials of the electrode sheet, fully utilize the ionic conductivity of the electrolyte and the electronic conductivity of the conductive agent, and ultimately improve the rate performance and cycle performance of solid-state batteries.

[0006] This invention relates to a method for preparing solid-state battery electrode sheets, which can be used in the manufacture of solid-state battery positive electrode sheets and / or solid-state battery negative electrode sheets. The obtained solid-state battery positive and negative electrode sheets can be further used in the manufacture of solid-state batteries, and the solid-state batteries made can be all-solid-state batteries, quasi-solid-state batteries, or semi-solid-state batteries.

[0007] The preparation method includes the following steps:

[0008] S1, electrode active material, electrolyte salt, conductive agent and binder are added to water in proportion and mixed evenly to form electrode slurry; the electrolyte salt includes LiCl and MCl3, wherein M is at least one of Zr, Yb, In, Y, Sc, Er, Hf and La;

[0009] S2, the electrode slurry is spray-dried to obtain composite electrode powder. During the process, LiCl and MCl3 react and form a composite coating layer containing Li3MCl6 on the surface of the electrode active material in the composite electrode powder. Then, the composite electrode powder is further vacuum-dried to obtain dehydrated composite electrode powder.

[0010] S3, the dehydrated composite electrode powder is first subjected to fiberization treatment, then rolled into a film, and finally hot-pressed onto the surface of the current collector to obtain a solid battery electrode sheet.

[0011] In some specific implementations, in step S1, LiCl and MCl3 are mixed in a molar ratio of 3:1.2 to 3:0.8; preferably, the molar ratio is 3:1.

[0012] In some specific implementations, in step S1, mixing is carried out by stirring and dispersing at a speed of 1000–3000 rpm for a duration of 1–10 h; preferably, the stirring speed is 10–100 rpm. Examples include: a dispersion speed of 1000 rpm and a dispersion time of 1 h; a dispersion speed of 2000 rpm and a dispersion time of 1 h; a dispersion speed of 3000 rpm and a dispersion time of 1 h; a dispersion speed of 1000 rpm and a dispersion time of 5 h; a dispersion speed of 2000 rpm and a dispersion time of 5 h; a dispersion speed of 3000 rpm and a dispersion time of 5 h; a dispersion speed of 1000 rpm and a dispersion time of 10 h; a dispersion speed of 2000 rpm and a dispersion time of 10 h; and a dispersion speed of 3000 rpm and a dispersion time of 10 h, etc.

[0013] In some specific implementations, in step S1, the conductivity of the water is not higher than 0.055 μS / cm, and preferably, the water is deionized water.

[0014] In some specific embodiments, in step S1, the weight ratio of electrode active material, conductive agent, binder, and electrolyte salt is (70-90):(1-5):(1-5):(5-20); preferably, the mass solid content of the electrode slurry is 25% to 30%. For example, the weight ratios are 70:1:1:5, 80:1:1:5, 90:1:1:5, 70:1:1:10, 80:1:1:10, 90:1:1:10, 70:1:1:20, 80:1:1:20, 90:1:1:20, 70:5:5:5, 80:5:5:5, 90:5:5:5, 70:5:5:10, 80:5:5:10, 90:5:5:10, 70:5:5:20, 80:5:5:20, 90:5:5:20, etc.

[0015] In some specific implementations, the electrode active material is a positive electrode active material or a negative electrode active material;

[0016] Preferably, the positive electrode active material includes lithium iron phosphate and / or lithium cobalt oxide;

[0017] Preferably, the negative electrode active material includes at least one of carbon nanotubes, graphite, silicon, and silicon-carbon materials;

[0018] Preferably, the conductive agent includes at least one of conductive carbon black, carbon nanotubes, and graphene;

[0019] Preferably, the binder is at least one of PTFE and PVDF.

[0020] In some specific embodiments, in step S2, the composite coating layer accounts for 5% to 20% of the weight of the composite electrode powder, and the composite coating layer includes Li3MCl6 and a conductive agent; preferably, the composite coating layer also includes a binder.

[0021] In some specific implementations, in step S2, the inlet temperature of the spray drying process is 200–250°C, and the outlet temperature is 150–200°C. For example, the inlet temperature is 200°C and the outlet temperature is 150°C; the inlet temperature is 200°C and the outlet temperature is 200°C; the inlet temperature is 250°C and the outlet temperature is 200°C; the inlet temperature is 220°C and the outlet temperature is 150°C; and the inlet temperature is 220°C and the outlet temperature is 200°C, etc.

[0022] In some specific implementations, in step S2, the vacuum drying process is carried out at a temperature of 60–100°C for a time of 1–20 hours. For example, the following temperatures are used: 60°C for 1 hour, 70°C for 1 hour, 90°C for 1 hour, 100°C for 1 hour, 60°C for 5 hours, 70°C for 5 hours, 90°C for 5 hours, 100°C for 5 hours, 60°C for 10 hours, 70°C for 10 hours, 80°C for 10 hours, 100°C for 10 hours, 60°C for 20 hours, 80°C for 20 hours, and 100°C for 20 hours. Preferably, the drying gas is dynamically replaced every 2 hours for drying times exceeding 4 hours.

[0023] In some specific embodiments, in step S3, the current collector is a perforated aluminum foil or a perforated copper foil; the thickness of the current collector is 5–20 μm, the pore diameter is 0.005–0.1 mm, and the pore density is 200–5000 pores / cm². 2 .

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] 1) LiCl and MCl3 form hydrates in step S1, dehydrate in step S2, and polymerize in situ on the surface of the electrode active material to form a composite coating layer containing Li3MCl6 and a conductive agent. This increases the contact area between the electrode active material and the electrolyte and conductive agent, forming high ionic conductivity channels and electronic conductivity channels. This fully utilizes the ionic conductivity of the electrolyte and the electronic conductivity of the conductive agent, greatly improving the conductivity of the solid-state battery electrode.

[0026] 2) Based on spray drying technology, a relatively small amount of binder is added during the mixing process in step S1, so that the final electrode has good adhesion, thereby reducing the internal resistance of the electrode and improving the rate performance of the solid-state battery.

[0027] 3) The solid-state battery positive electrode sheet made by this invention can be adapted to the solid-state battery negative electrode sheet made by this invention, and can also be adapted to the negative electrode sheet of lithium metal, sodium or high porosity carbon nanotubes to prepare solid-state batteries of different systems. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the composite electrode powder in Example 1. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Experimental methods not specified in the embodiments were performed according to conventional methods and conditions.

[0030] The main raw materials involved in the preparation process are as follows:

[0031] The positive electrode active material is lithium iron phosphate from Jiangsu Leneng Battery Co., Ltd., model N2;

[0032] The negative electrode active material is silicon-carbon from Fujian Xiangfenghua New Energy Materials Co., Ltd., model SCX-11;

[0033] The conductive agent is SP-Li from Shenzhen Glafit Battery Materials Co., Ltd.;

[0034] The binder is PTFE F106 from Daikin Fluorochemicals (China) Co., Ltd.

[0035] The electrolyte salts were LiCl (model L812571) from Maclean and InCl3 (model 1811750);

[0036] The positive electrode foil is perforated aluminum foil from Shanxi Woteheimer New Material Technology Co., Ltd., with a thickness of 10μm, a pore diameter of 0.050mm, and a pore density of 3000 pores / cm². 2 ;

[0037] The negative electrode foil is a perforated copper foil from Shanxi Wotech New Material Technology Co., Ltd., with a thickness of 8μm, a hole diameter of 0.050mm, and a hole density of 3000 holes / cm². 2 .

[0038] Example 1

[0039] The preparation process of the positive electrode sheet is as follows:

[0040] S1, lithium iron phosphate, conductive agent SP-Li, binder PTFE, electrolyte salt LiCl and InCl3 were added to deionized water in a weight ratio of 85:2.5:2.5:3.65:6.35, and then stirred at a revolution speed of 25 rpm (dispersion speed of 1500 rpm) for 4 hours. At this time, a positive electrode slurry with a solid content of 30% by mass was obtained by uniform mixing.

[0041] S2, the above positive electrode slurry is subjected to spray drying. The inlet temperature of the spray drying equipment is 230℃ and the outlet temperature is 180℃, resulting in composite electrode powder. Its scanning electron microscope image is shown below. Figure 1 As shown; then, under vacuum, it was dried at 80°C for 10 hours, with nitrogen gas dynamically replacing the powder every 2 hours to obtain dehydrated composite electrode powder;

[0042] S3, the above-mentioned dehydrated composite electrode powder is placed in a high-speed disperser for mixing. First, it is mixed at 700 rpm for 5 minutes, then at 11000 rpm for 5 minutes to obtain fibrous material. The fibrous material is then rolled by rollers to obtain a positive electrode film with a thickness of 120 μm. The positive electrode film is then hot-pressed onto both sides of a perforated aluminum foil using a flatbed hot press at 150°C for 15 seconds, finally yielding a film with a thickness of 185 μm and a compaction density of 2.5 g / cm³. 3 The positive electrode sheet.

[0043] The preparation of the negative electrode differs from that of the positive electrode described above. Instead of lithium iron phosphate as the positive electrode active material, the negative electrode active material is silicon-carbon, and the foil is perforated copper foil; all other preparation conditions remain unchanged. The resulting negative electrode film has a thickness of 100 μm, and the negative electrode sheet obtained by double-sided hot pressing has a thickness of 108 μm and a compaction density of 1.6 g / cm³. 3 .

[0044] Example 2

[0045] The difference between this embodiment and Example 1 is that the positive electrode active material is lithium cobalt oxide, while the other preparation conditions remain the same. The resulting positive electrode film has a thickness of 120 μm, the positive electrode sheet has a thickness of 133 μm, and the compaction density is 4.0 g / cm³. 3 The negative electrode film thickness is 120 μm, the negative electrode sheet thickness is 133 μm, and the compaction density is 1.6 g / cm³.3 .

[0046] Example 3

[0047] The difference between this embodiment and Embodiment 1 is that the negative electrode film is made of carbon nanotubes (CNTs), a dispersant (PVP), and a binder (PVDF), with a CNT:PVP:PVDF ratio of 90:5:5 and a slurry solid content of 10%. The resulting negative electrode sheet has a thickness of 54 μm, a porosity of 90%, and a single-sided negative electrode film thickness of 23 μm.

[0048] Example 4

[0049] The difference between this embodiment and Embodiment 2 is that lithium metal is used as the negative electrode active material to fabricate a 2032 coin cell. All other preparation conditions remain unchanged.

[0050] Comparative Example 1

[0051] The preparation process of the positive electrode sheet is as follows:

[0052] Lithium iron phosphate, conductive agent SP-Li, binder PTFE, and electrolyte Li3InCl6 were mixed in a high-speed disperser at a weight ratio of 85:2.5:2.5:10. The mixture was first processed at 700 rpm for 5 minutes, then at 11000 rpm for 5 minutes to obtain fibrous material. The fibrous material was then rolled to obtain a positive electrode film with a thickness of 120 μm. The positive electrode film was then hot-pressed onto both sides of a perforated aluminum foil using a flatbed hot press at 150℃ for 15 seconds, resulting in a final film with a thickness of 185 μm and a compaction density of 2.5 g / cm³. 3 The positive electrode sheet.

[0053] The preparation of the negative electrode differs from that of the positive electrode described above. Instead of lithium iron phosphate as the positive electrode active material, the negative electrode active material is silicon-carbon, and the foil is perforated copper foil; all other preparation conditions remain unchanged. The resulting negative electrode film has a thickness of 100 μm, the negative electrode sheet thickness is 108 μm, and the compaction density is 1.6 g / cm³. 3 .

[0054] Comparative Example 2

[0055] The difference between this comparative example and Comparative Example 1 is that lithium cobalt oxide was used as the positive electrode active material. The prepared positive electrode film thickness was 120 μm, the positive electrode sheet thickness was 133 μm, and the compaction density was 4.0 g / cm³. 3 .

[0056] The preparation of the negative electrode differs from that of the positive electrode described above. Instead of lithium cobalt oxide as the positive electrode active material, the negative electrode active material is silicon carbon, and the foil is perforated copper foil; all other preparation conditions remain unchanged. The resulting negative electrode film has a thickness of 120 μm, the negative electrode sheet thickness is 133 μm, and the compaction density is 1.6 g / cm³. 3 .

[0057] Comparative Example 3

[0058] The preparation process of the positive electrode sheet is the same as that of Comparative Example 1, and the preparation process of the negative electrode sheet is the same as that of Example 3.

[0059] The positive and negative electrode sheets prepared in Examples 1-4 and Comparative Examples 1-3 were assembled with an electrolyte separator, die-cut, and stacked into battery units, and then solid-state batteries were obtained through formation and capacity testing.

[0060] The thickness of the electrolyte membrane is 10–20 μm, of which the thickness of the electrolyte coating is 1–5 μm.

[0061] The solid electrolyte material is at least one of LATP (lithium titanium aluminum phosphate), LLZO (lithium lanthanum tantalum oxide), or LLZTO (lithium lanthanum tantalum oxide).

[0062] The electrolyte membrane thickness selected in Examples 1 to 4 is 15 μm, and the electrolyte coating thickness is 3 μm; the solid electrolyte material selected in Example 1 is LATP, the solid electrolyte material selected in Example 2 is LLZO, and the solid electrolyte material selected in Examples 3 and 4 is LLZTO.

[0063] The batteries prepared based on Examples 1-4 and Comparative Examples 1-3 were tested under a constant temperature of 25°C, and the test records are shown in Table 1.

[0064] Table 1 Battery Parameter Table

[0065] Parameter performance Battery Type 1C discharge capacity retention 5C discharge capacity retention 10C discharge capacity retention 1C cycle 200-cycle capacity retention 3C cycle 400-cycle capacity retention Example 1 Soft pack 99.9% 93.5% 90.4% 99.2% 97.5% Example 2 Soft pack 99.9% 93.8% 90.6% 98.8% 97% Example 3 Soft pack 99.9% 94.5% 91.1% 99.3% 97.2% Example 4 2032 buckle 99.8% 85% 70% 98.2% 95.2% Comparative Example 1 Soft pack 98.5% 74.2% 57% 92% 87% Comparative Example 2 Soft pack 98.3% 74.7% 57.6% 90.5% 85.7% Comparative Example 3 Soft pack 98.2% 75.8% 58% 91% 86%

[0066] As can be seen from Table 1, compared with the comparative examples, after the solid electrolyte and conductive agent coating layer obtained by in-situ polymerization on the surface of the positive and negative electrode active materials according to the method of the present invention, due to the contact area between the electrode active materials and the electrolyte and conductive agent, a high ionic conductivity channel and an electronic conductivity channel are formed, which fully utilizes the ionic conductivity of the electrolyte and the electronic conductivity of the conductive agent, and the rate performance and cycle performance of the battery are significantly improved.

[0067] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a solid-state battery electrode sheet, characterized in that, Includes the following steps: S1, electrode active material, electrolyte salt, conductive agent and binder are added to water in proportion and mixed evenly to form electrode slurry; the electrolyte salt includes LiCl and MCl3, wherein M is at least one of Zr, Yb, In, Y, Sc, Er, Hf and La; S2, the electrode slurry is spray-dried to obtain composite electrode powder. During the process, LiCl and MCl3 react to form a composite coating layer containing Li3MCl6 on the surface of the electrode active material in the composite electrode powder. The composite coating layer includes a binder, Li3MCl6 and a conductive agent. Then, the composite electrode powder is further vacuum-dried to obtain dehydrated composite electrode powder. S3, the dehydrated composite electrode powder is first subjected to fiberization treatment, then rolled into a film, and finally hot-pressed onto the surface of the current collector to obtain a solid battery electrode sheet. The electrode active material is either a positive electrode active material or a negative electrode active material.

2. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, In step S1, the mixture is carried out by stirring and dispersing at a speed of 1000-3000 rpm for 1-10 hours.

3. The method for preparing the solid-state battery electrode sheet according to claim 2, characterized in that, The stirring speed is 10 to 100 rpm.

4. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, In step S1, the weight ratio of electrode active material, electrolyte salt, conductive agent and binder is (70-90):(5-20):(1-5):(1-5).

5. The method for preparing the solid-state battery electrode sheet according to claim 1 or 4, characterized in that, The electrode slurry has a solid content of 25% to 30% by mass.

6. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, The positive electrode active material includes lithium iron phosphate and / or lithium cobalt oxide.

7. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, The negative electrode active material includes at least one of carbon nanotubes, graphite, silicon, and silicon-carbon materials.

8. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, The conductive agent includes at least one of conductive carbon black, carbon nanotubes, and graphene.

9. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, The adhesive is at least one of PTFE and PVDF.

10. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, In step S2, the weight ratio of the composite coating layer to the composite electrode powder is 5% to 20%.

11. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, In step S2, the inlet temperature of the spray drying process is 200-250°C, and the outlet temperature is 150-200°C.

12. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, In step S2, the temperature of the vacuum drying process is 60–100°C, and the time is 1–20 h.

13. The method for preparing the solid-state battery electrode sheet according to claim 1, characterized in that, In step S3, the current collector is a perforated aluminum foil or a perforated copper foil; the thickness of the current collector is 5–20 μm, the pore diameter is 0.005–0.1 mm, and the pore density is 200–5000 pores / cm². 2 .

14. A solid-state battery electrode sheet, characterized in that, It is prepared by any one of the preparation methods described in claims 1-13.

15. The application of the solid-state battery electrode sheet of claim 14 in a solid-state battery.

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