Composite electrode sheet and manufacturing method thereof, solid-state battery and electrical device

Abstract

The present application relates to a composite electrode sheet and its manufacturing method, a solid-state battery, and an electrical device, belonging to the field of solid-state battery technology. The present application provides a composite electrode sheet manufacturing method comprising the following steps: S1, mixing electrode materials, a binder, a conductive agent, and a solvent to obtain a slurry; S2, applying the slurry to at least one surface of a current collector, drying, and then rolling to obtain an electrode sheet; S3, forming a solid electrolyte layer on the surface of the electrode sheet coated with the slurry; the process conditions of the vacuum magnetron sputtering method in step S3 include a background vacuum of 5×10 ‑5 ~6×10 ‑5 Pa, sputtering pressure 0.3-0.7 Pa, sputtering power 3.5-5.5 kW. The solid electrolyte layer in the composite electrode sheet manufactured by the manufacturing method of the present application has no pores, which can effectively prevent the growth of lithium dendrites during the charge and discharge process and avoid the occurrence of short circuits.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state batteries, and in particular to a composite electrode sheet and a manufacturing method thereof, a solid-state battery and an electrical device. Background Art

[0002] Traditional lithium-ion batteries use an organic liquid electrolyte to transport lithium ions, but this can be prone to problems such as leakage and flatulence, and in severe cases, can even cause the battery to combust and explode, posing a safety hazard. Solid-state batteries replace organic liquid electrolytes with solid-state electrolytes, significantly improving battery safety. Unlike traditional lithium-ion batteries, the positive and negative electrodes of solid-state batteries are composed of active material, a binder, a conductive agent, a solid electrolyte, and a current collector. Traditionally, solid-state batteries are manufactured by applying a solid electrolyte slurry to the positive and negative electrode surfaces, or by melting and hot-pressing the solid electrolyte into a film, which is then wound or laminated with the positive and negative electrode sheets. However, when the solid electrolyte slurry is applied to the positive and negative electrode surfaces and then dried, vapor escapes from the solid electrolyte coating, forming pores. During subsequent charge and discharge cycles, lithium dendrites can grow along these pores, causing a short circuit between the positive and negative electrodes. Summary of the Invention

[0003] One of the purposes of the present application is to provide a composite electrode sheet and its manufacturing method, a solid-state battery and an electrical device. The solid electrolyte layer in the composite electrode sheet manufactured by the manufacturing method of the present application is free of pores, and can effectively prevent the growth of lithium dendrites during the charging and discharging process, thereby avoiding the occurrence of short circuits.

[0004] To achieve the above objectives, the specific technical solutions are as follows:

[0005] The present application provides a method for manufacturing a composite electrode sheet, comprising the following steps:

[0006] S1, mixing electrode materials, binder, conductive agent and solvent to obtain slurry;

[0007] S2, coating the slurry on at least one surface of a current collector, drying and then rolling to obtain an electrode sheet;

[0008] S3, forming a solid electrolyte layer on the surface of the electrode sheet coated with the slurry by a vacuum magnetron sputtering method;

[0009] The process conditions of the vacuum magnetron sputtering method in step S3 include a background vacuum degree of 5×10 -3 ~6×10 -3 Pa, sputtering gas pressure 0.3~0.7Pa, sputtering power 3.5~5.5kW.

[0010] In some embodiments, the process conditions of the vacuum magnetron sputtering method in step S3 further include a distance between the target and the substrate being 20 to 50 mm.

[0011] In some embodiments, the material of the solid electrolyte layer includes one or more of an oxide solid electrolyte and a sulfide solid electrolyte;

[0012] Optionally, the oxide solid electrolyte includes Li 1.3 Si 0.225 V 1.36 (PO5)3、Li 0.35 La 0.51 TiO 2.95 and Li7La3Zr2O 12 One or more of;

[0013] Optionally, the sulfide solid electrolyte includes Li 10 GeP2S 12 , Li2S, P2S5 and SiS2.

[0014] In some embodiments, the solid electrolyte layer has a thickness of 5 to 6 μm.

[0015] In some embodiments, the electrode material includes a positive electrode material or a negative electrode material;

[0016] The mass ratio of the positive electrode material, the binder and the conductive agent is 98:1:1;

[0017] The mass ratio of the negative electrode material, the binder and the conductive agent is 95.5:3.5:1.

[0018] In some embodiments, the method for preparing the electrode material comprises the following steps:

[0019] After the electrode active material is mixed with the solid electrolyte, ball milling, sintering, crushing and screening are sequentially performed to coat the surface of the electrode active material with the solid electrolyte to obtain the electrode material.

[0020] In some embodiments, the electrode active material includes a cathode active material.

[0021] In some embodiments, the electrode active material includes a positive electrode active material, and the positive electrode active material includes LiCoO2, LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2 and NCA ternary materials.

[0022] In some embodiments, the electrode active material includes a negative electrode active material.

[0023] In some embodiments, the electrode active material includes a negative electrode active material, and the negative electrode active material includes one or more of metallic lithium, graphite, and silicon-carbon material.

[0024] In some embodiments, the binder includes one or more of PVDF, CMC, and SBR.

[0025] In some embodiments, the conductive agent includes one or more of graphene, conductive carbon black, carbon nanotubes, Ketjen black, and conductive graphite.

[0026] In some embodiments, the solvent includes one or more of NMP and water.

[0027] In some embodiments, the solid electrolyte includes one or more of an oxide solid electrolyte and a sulfide solid electrolyte;

[0028] Optionally, the oxide solid electrolyte includes Li 1.3 Si 0.225 V 1.36 (PO5)3、Li 0.35 La 0.51 TiO 2.95 and Li7La3Zr2O 12 One or more of;

[0029] Optionally, the sulfide solid electrolyte includes Li 10 GeP2S 12 , Li2S, P2S5 and SiS2.

[0030] In some embodiments, the process conditions of the sintering treatment include a sintering temperature of 800-1000° C. and a sintering time of 1-3 hours.

[0031] In some embodiments, the sieve used in the screening process has an aperture of 200-250 meshes.

[0032] In some embodiments, the D50 of the electrode material is 8 to 20 μm.

[0033] In some embodiments, the solid content of the slurry is 30% to 76%.

[0034] In some embodiments, the viscosity of the slurry is 3000 to 9000 mPa·s.

[0035] In some embodiments, the current collector includes one or more of aluminum foil and copper foil.

[0036] In some embodiments, the mass ratio of the electrode active material to the solid electrolyte is (85-95):(5-15).

[0037] In some embodiments, the thickness of the electrode sheet is 123-155 μm.

[0038] The present application also provides a composite electrode sheet manufactured by the above manufacturing method.

[0039] The present application also provides a solid-state battery, comprising a composite electrode sheet manufactured by the above-mentioned manufacturing method or the above-mentioned composite electrode sheet.

[0040] The present application also provides an electrical device comprising the above-mentioned solid-state battery.

[0041] Compared with traditional technologies, the composite electrode sheet and its manufacturing method, solid-state battery and power-consuming device have the following advantages:

[0042] (1) The particles of the solid electrolyte layer in the composite electrode sheet produced by the above-mentioned production method are tightly bonded and have no pores. Moreover, when the composite positive electrode sheet and the composite negative electrode sheet are assembled into a solid-state battery, the two are tightly bonded and have no pores, which effectively prevents the growth of lithium dendrites during the charge and discharge process and avoids the occurrence of short circuits.

[0043] (2) The above-mentioned manufacturing method utilizes the background vacuum, sputtering gas pressure and sputtering power to control the crystal size of the solid electrolyte in the solid electrolyte layer, reduce the gap between the solid electrolyte crystals, effectively prevent the growth of lithium dendrites, and at the same time reduce the interface resistance between the composite electrode sheet and the solid electrolyte layer, thereby improving the cycle performance of the solid-state battery. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] In the description of the present invention, unless otherwise defined, technical terms and professional words not explicitly described have the same meanings as those generally understood by those skilled in the art and are common knowledge. Methods not explicitly described are conventional methods known to those skilled in the art. The term "multiple" in the present invention means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0046] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0047] An embodiment of the present application provides a method for manufacturing a composite electrode sheet, comprising the following steps:

[0048] S1, mixing electrode materials, binder, conductive agent and solvent to obtain slurry;

[0049] S2, coating the slurry on at least one surface of the current collector, drying and then rolling to obtain an electrode sheet;

[0050] S3, forming a solid electrolyte layer on the surface of the electrode sheet coated with the slurry by vacuum magnetron sputtering to obtain a composite electrode sheet;

[0051] The process conditions of the vacuum magnetron sputtering method in step S3 include a background vacuum degree of 5×10 -3 ~6×10 -3 Pa, sputtering gas pressure 0.3~0.7Pa, sputtering power 3.5~5.5kW.

[0052] Solid-state electrolytes are applied to electrodes using a traditional coating method to form a solid electrolyte layer. During drying, vapor escapes from the solid electrolyte layer, forming pores. During the subsequent charge and discharge process, lithium dendrites grow along these pores, causing a short circuit between the positive and negative electrodes. The size of lithium dendrites is closely related to factors such as the electrodes, electrolyte, and testing in solid-state batteries. They are typically in the μm range, for example, 3μm, 3.5μm, 5.0μm, 5.5μm, 5.8μm, 5.0μm, 5.2μm, 5.6μm, or 6.0μm. The solid electrolyte layer formed on the surface of the electrode sheet by vacuum magnetron sputtering in this application reduces the gap between crystals, makes the particles tightly bound and has no pores, and avoids the pores formed by the escape of steam from the solid electrolyte layer during drying. Therefore, in the subsequent charge and discharge process, the electrode sheet prepared by the preparation method of this application can effectively prevent the growth of lithium dendrites and avoid the occurrence of short circuit. At the same time, the crystal size of the solid electrolyte in the solid electrolyte layer can be controlled by the background vacuum, sputtering pressure and sputtering power, which can reduce the interface resistance between the composite electrode sheet and the solid electrolyte layer, and further improve the cycle performance of the solid-state battery. It should be noted that the raw materials for preparing the electrode material include electrode active materials. The electrode active materials are divided into positive electrode active materials and negative electrode active materials. According to the different electrode active materials, the electrode material can be divided into positive electrode material and negative electrode material, the slurry can be divided into positive electrode slurry and negative electrode slurry, the electrode sheet can be divided into positive electrode sheet and negative electrode sheet, and the composite electrode sheet is divided into composite positive electrode sheet and composite negative electrode sheet.

[0053] It is understood that the background vacuum can be 5×10 -3 ~6×10 -3 Pa, for example, it can be 5×10 -3 Pa, 5.1×10 -3Pa, 5.2×10 -3 Pa, 5.3×10 -3 Pa, 5.4×10 -3 Pa, 5.5×10 -3 Pa, 5.6×10 -3 Pa, 5.7×10 -3 Pa, 5.8×10 -3 Pa, 5.9×10 -3 Pa or 6×10 -3 The sputtering gas pressure may be any value between 0.3 and 0.7 Pa, for example, 0.3 Pa, 0.32 Pa, 0.35 Pa, 0.36 Pa, 0.38 Pa, 0.4 Pa, 0.42 Pa, 0.45 Pa, 0.46 Pa, 0.48 Pa, 0.5 Pa, 0.52 Pa, 0.55 Pa, 0.56 Pa, 0.58 Pa, 0.6 Pa, 0.62 Pa, 0.65 Pa, 0.66 Pa, 0.68 Pa or 0.7 Pa. The sputtering power can be any value between 3.5 and 5.5 kW, for example, it can be 3.5 kW, 3.6 kW, 3.7 kW, 3.8 kW, 3.9 kW, 4.0 kW, 4.1 kW, 4.2 kW, 4.3 kW, 4.4 kW, 4.5 kW, 4.6 kW, 4.7 kW, 4.8 kW, 4.9 kW, 5.0 kW, 5.2 kW or 5.5 kW.

[0054] In some embodiments, the process conditions of the vacuum magnetron sputtering method in step S3 also include a distance between the target and the substrate of 20 to 50 mm. It should be noted that in this application, the substrate refers to the electrode sheet, that is, the positive electrode sheet or the negative electrode sheet, and the target refers to the sputtering source, that is, the solid electrolyte sputtering source. It is understandable that the distance between the target and the substrate can be any value between 20 and 50 mm, for example, it can be 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, 32 mm, 34 mm, 36 mm, 38 mm, 40 mm, 42 mm, 44 mm, 46 mm, 48 mm or 50 mm, etc.

[0055] In some embodiments, the material of the solid electrolyte layer includes one or more of an oxide solid electrolyte and a sulfide solid electrolyte;

[0056] Optionally, the oxide solid electrolyte includes Li 1.3 Si 0.225 V 1.36 (PO5)3、Li 0.35 La 0.51 TiO 2.95 and Li7La3Zr2O 12 One or more of;

[0057] Optionally, the sulfide solid electrolyte includes Li 10 GeP2S 12 , Li2S, P2S5 and SiS2.

[0058] It should be noted that the above-mentioned oxide solid electrolyte and sulfide solid electrolyte are selected in this application because these two electrolytes have high ionic conductivity.

[0059] In some embodiments, the solid electrolyte layer has a thickness of 5 to 6 μm.

[0060] It can be understood that the thickness of the solid electrolyte layer can be 5μm, 5.1μm, 5.2μm, 5.3μm, 5.4μm, 5.5μm, 5.6μm, 5.7μm, 5.8μm, 5.9μm or 6μm, and the thickness of the solid electrolyte layer can also be any value between 5 and 6μm.

[0061] In some embodiments, the electrode material comprises a positive electrode material or a negative electrode material;

[0062] The mass ratio of positive electrode material, binder and conductive agent is 98:1:1;

[0063] The mass ratio of the negative electrode material, the binder and the conductive agent is 95.5:3.5:1.

[0064] It should be noted that the raw materials for preparing electrode materials include electrode active materials, which are divided into positive electrode active materials and negative electrode active materials. Depending on the electrode active materials, electrode materials can be divided into positive electrode materials and negative electrode materials. The binder mixed with the negative electrode material can be CMC and SBR. The mass ratio of the negative electrode material, binder, and conductive agent can be 95.5:1.5:2:1.

[0065] In some embodiments, the method for preparing the electrode material comprises the following steps:

[0066] After the electrode active material is mixed with the solid electrolyte, ball milling, sintering, crushing and screening are carried out in sequence to coat the surface of the electrode active material with the solid electrolyte to obtain the electrode material.

[0067] It should be noted that the solid electrolyte is first coated on the surface of the electrode active material to obtain the electrode material, and then the electrode material, binder, conductive agent and solvent are mixed to obtain a slurry to prepare a composite electrode sheet. This is because the simultaneous construction of ion and electron channels on the surface of the electrode active material is beneficial to reducing the internal resistance of the battery cell.

[0068] In some embodiments, the electrode active material includes a cathode active material.

[0069] In some embodiments, the electrode active material includes a positive electrode active material, and the positive electrode active material includes LiCoO2, LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2 and NCA ternary materials. It is understood that the positive electrode active material can be LiCoO2, LiNi 0.8 Co 0.1 Mn 0.1 Any one of O2 and NCA ternary materials, or LiCoO2, LiNi 0.8 Co 0.1 Mn 0.1 A mixture of multiple O2 and NCA ternary materials in any proportion.

[0070] In some embodiments, the electrode active material includes a negative electrode active material.

[0071] In some embodiments, the electrode active material includes a negative electrode active material, and the negative electrode active material includes one or more of metallic lithium, graphite, and a silicon-carbon material. It is understood that the negative electrode active material can be any one of metallic lithium, graphite, and a silicon-carbon material, or a composite or mixture of multiple materials thereof in any ratio.

[0072] In some embodiments, the binder includes one or more of PVDF, CMC, and SBR.

[0073] In some embodiments, the conductive agent includes one or more of graphene, conductive carbon black, carbon nanotubes, Ketjen black, and conductive graphite.

[0074] In some embodiments, the solvent includes one or more of NMP and water.

[0075] In some embodiments, the solid electrolyte includes one or more of an oxide solid electrolyte and a sulfide solid electrolyte;

[0076] Optionally, the oxide solid electrolyte includes Li 1.3 Si 0.225 V 1.36 (PO5)3、Li 0.35 La 0.51 TiO 2.95 and Li7La3Zr2O 12 One or more of;

[0077] Optionally, the sulfide solid electrolyte includes Li 10 GeP2S 12 , Li2S, P2S5 and SiS2.

[0078] In some embodiments, the process conditions of the sintering treatment include a sintering temperature of 800-1000° C. and a sintering time of 1-3 hours.

[0079] It can be understood that the sintering temperature can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃ or 1000℃, and the sintering temperature can also be other values between 800 and 1000℃. The sintering time can be 1h, 1.5h, 2h, 2.5h or 3h, and the sintering time can also be other values between 1 and 3h.

[0080] In some embodiments, the sieve used in the sieving process has an aperture of 200-250 mesh.

[0081] In some embodiments, the D50 of the electrode material is 8 to 20 μm. It should be noted that, depending on the different electrode active materials, the electrode materials are divided into positive electrode materials and negative electrode materials. The D50 of the positive electrode material is 8 to 12 μm, for example, it can be 8 μm, 8.2 μm, 8.5 μm, 8.7 μm, 9 μm, 9.2 μm, 9.5 μm, 9.8 μm, 10 μm, 10.2 μm, 10.5 μm, 10.7 μm, 10.9 μm, 11 μm, 11.3 μm, 11. the D50 of the negative electrode material is 16 to 20 μm, for example, it can be 16 μm, 16.3 μm, 16.5 μm, 16.8 μm, 17 μm, 17.2 μm, 17.4 μm, 17.6 μm, 17.8 μm, 18 μm, 18.2 μm, 18.3 μm, 18.5 μm, 18.8 μm, 19 μm, 19.5 μm or 20 μm, etc.

[0082] In some embodiments, the solid content of the slurry is 30% to 76%. It is understood that the solid content of the slurry can be 30%, 32%, 35%, 36%, 38%, 40%, 43%, 45%, 48%, 50%, 53%, 56%, 58%, 60%, 62%, 65%, 66%, 68%, 70%, 72%, 74% or 76%. The solid content of the slurry can also be other values between 30% and 76%. It should be noted that, depending on the different electrode active materials, the slurry is divided into positive electrode slurry and negative electrode slurry, with the solid content of the positive electrode slurry being 30% to 76% and the solid content of the negative electrode slurry being 50% to 55%.

[0083] In some embodiments, the viscosity of the slurry is 3000 to 9000 mPa·s. It can be understood that the viscosity of the slurry can be 3000mPa·s, 3200mPa·s, 3500mPa·s, 3600mPa·s, 3800mPa·s, 4000mPa·s, 4200mPa·s, 4500mPa·s, 4600mPa·s, 4800mPa·s, 5000mPa·s, 5300mPa·s, 5600mPa·s, 5800mPa·s, 6000mPa·s, 63000mPa·s, 6600mPa·s, 6800mPa·s, 7000mPa·s, 7300mPa·s, 7600mPa·s, 8000mPa·s, 8300mPa·s, 8600mPa·s, 8800mPa·s or 9000mPa·s. The viscosity of the slurry may also be other values between 3000 and 9000 mPa·s.

[0084] In some embodiments, the current collector includes one or more of aluminum foil and copper foil.

[0085] In some embodiments, the mass ratio of the electrode active material to the solid electrolyte is (85-95):(5-15). It is understood that the mass ratio of the electrolytic active material to the solid electrolyte can be 85:15, 87:13, 88:12, 90:10, 92:8, 93:7, 94:6, or 95:5, etc.

[0086] In some embodiments, the thickness of the electrode sheet is 123 to 155 μm. It is understandable that the thickness of the electrode sheet can be any value between 123 and 155 μm, for example, it can be 123 μm, 124 μm, 125 μm, 126 μm, 127 μm, 128 μm, 129 μm, 130 μm, 131 μm, 132 μm, 133 μm, 134 μm, 135 μm, 136 μm, 137 μm, 138 μm, 139 μm, 140 μm, 142 μm, 144 μm, 146 μm, 148 μm, 150 μm or 155 μm. It should be noted that, depending on the electrode active material, the electrode sheet is divided into two types: positive electrode sheet and negative electrode sheet. The thickness of the positive electrode sheet is 123 to 153 μm; the thickness of the negative electrode sheet is 135 to 155 μm.

[0087] Another embodiment of the present application provides a composite electrode sheet produced by the above-described production method. It is understood that the raw materials for preparing the electrode material include electrode active materials, which are divided into positive electrode active materials and negative electrode active materials. Depending on the electrode active materials, the composite electrode sheet can be divided into a composite positive electrode sheet and a composite negative electrode sheet.

[0088] Another embodiment of the present application provides a solid-state battery, including a composite electrode sheet manufactured by the above-mentioned manufacturing method or the above-mentioned composite electrode sheet.

[0089] It should be noted that the solid-state battery in this application includes but is not limited to a composite positive electrode sheet and a composite negative electrode sheet wound or stacked, wherein the composite positive electrode sheet can be a composite positive electrode sheet or the composite positive electrode sheet produced by the above-mentioned production method, and the composite negative electrode sheet can be a composite negative electrode sheet or the composite negative electrode sheet produced by the above-mentioned production method. The composite positive electrode sheet and composite negative electrode sheet produced by the above-mentioned production method have a positive electrode sheet that is tightly bonded to the solid electrolyte layer, and a negative electrode sheet that is tightly bonded to the solid electrolyte layer. When assembled into a solid-state battery, the composite positive electrode sheet and the composite negative electrode sheet are also tightly bonded. Therefore, the composite positive electrode sheet and the composite negative electrode sheet have excellent ion conductivity, which effectively reduces the interface resistance of the solid-state battery.

[0090] Another embodiment of the present application provides an electrical device including the above-mentioned solid-state battery.

[0091] It should be noted that the solid-state battery in the above-mentioned electrical devices can be used as a power source or energy storage unit. The above-mentioned electrical devices include but are not limited to electric vehicles, such as pure electric vehicles, plug-in hybrid electric vehicles, electric bicycles, etc.

[0092] The present application is further described in detail below with reference to specific embodiments and comparative examples.

[0093] Example 1

[0094] (a) Prepare the positive electrode material as follows:

[0095] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 and oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3 was mixed in a mass ratio of 90:10 and sintered at 900°C for 2h. The sintered material was crushed and sieved using a 200-mesh sieve to obtain a positive electrode material with a D50 of 10μm.

[0096] (b) Prepare the composite positive electrode sheet as follows:

[0097] S1. The positive electrode material, PVDF, carbon nanotubes, and NMP are uniformly mixed to obtain a positive electrode slurry, wherein the mass ratio of the positive electrode material, PVDF, and carbon nanotubes is 98:1:1, the solid content of the positive electrode slurry is 76%, and the viscosity of the positive electrode slurry is 7800 mPa·s;

[0098] S2, according to 552mg / cm2 The positive electrode slurry was evenly coated on both sides of the aluminum foil with a coating amount of , and then dried and rolled to obtain a positive electrode sheet with a thickness of 133 μm;

[0099] S3, vacuum magnetron sputtering method (the specific process conditions of vacuum magnetron sputtering method are: background vacuum degree 5×10 - 5 Pa, sputtering pressure 0.3Pa, the distance between the target and the substrate is 50mm, and the sputtering power is 5.5kW) to deposit the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3 is plated on the above-mentioned positive electrode sheet to obtain a composite positive electrode sheet, and the thickness of the solid electrolyte layer is 5μm.

[0100] (c) Prepare the negative electrode material as follows:

[0101] The negative electrode active material graphite and the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3 was mixed in a mass ratio of 90:10 and sintered at 900°C for 2h. The sintered material was crushed and sieved using a 200-mesh sieve to obtain a negative electrode material with a D50 of 18μm.

[0102] (d) Prepare the composite negative electrode sheet as follows:

[0103] S1. Evenly mix the above-mentioned negative electrode material, CMC, SBR, carbon nanotubes, and water to obtain a negative electrode slurry, wherein the mass ratio of the negative electrode material, CMC, SBR, and carbon nanotubes is 95.5:1.5:2:1, the solid content of the negative electrode slurry is 55%, and the viscosity of the negative electrode slurry is 5500 mPa·s;

[0104] S2, according to 232mg / cm 2 The negative electrode slurry was evenly coated on both sides of the copper foil in an amount of , and then dried and rolled to obtain a negative electrode sheet with a thickness of 155 μm;

[0105] S3, vacuum magnetron sputtering method (the specific process conditions of vacuum magnetron sputtering method are: background vacuum degree 5×10 - 5 Pa, sputtering pressure 0.3Pa, the distance between the target and the substrate is 50mm, and the sputtering power is 5.5kW) to deposit the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3 is plated on the above-mentioned negative electrode sheet to obtain a composite negative electrode sheet, and the thickness of the solid electrolyte layer is 5μm.

[0106] (e) Preparing a button cell: Winding the composite positive electrode sheet and the composite negative electrode sheet to form a roll core, which is then sealed in a shell to produce a 1255 button cell.

[0107] Example 2

[0108] Example 2 is basically the same as Example 1, except that:

[0109] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the sputtering pressure is 0.4Pa;

[0110] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering gas pressure is 0.4Pa.

[0111] Example 3

[0112] Example 3 is basically the same as Example 1, except that:

[0113] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the sputtering pressure is 0.5Pa;

[0114] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering pressure is 0.5Pa.

[0115] Example 4

[0116] Example 4 is basically the same as Example 1, except that:

[0117] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the sputtering pressure is 0.6Pa;

[0118] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering gas pressure is 0.6Pa.

[0119] Example 5

[0120] Example 5 is basically the same as Example 1, except that:

[0121] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the sputtering pressure is 0.7Pa;

[0122] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering gas pressure is 0.7Pa.

[0123] Example 6

[0124] Example 6 is basically the same as Example 3, except that:

[0125] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode sheet, the sputtering power is 3.5kW;

[0126] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering power is 3.5kW.

[0127] Example 7

[0128] Example 7 is basically the same as Example 3, except that:

[0129] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode sheet, the sputtering power is 4.5kW;

[0130] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36When (PO5)3 is plated on the negative electrode sheet, the sputtering power is 4.5kW.

[0131] Example 8

[0132] Example 8 is basically the same as Example 3, except that:

[0133] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the background vacuum is 5.5×10 -5 Pa;

[0134] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode, the background vacuum is 5.5×10 -5 Pa.

[0135] Example 9

[0136] Example 9 is basically the same as Example 3, except that:

[0137] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the background vacuum is 6×10 -5 Pa;

[0138] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode, the background vacuum is 6×10 -5 Pa.

[0139] Comparative Example 1

[0140] Comparative Example 1 is substantially the same as Example 3, except that:

[0141] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36(PO5)3 and PVDF were mixed in a mass ratio of 99:1, and then NMP was added and mixed evenly to obtain a mixed slurry with a solid content of 70%. The viscosity of the mixed slurry was 7500 mPa·s. The mixed slurry was coated on the positive electrode sheet. After coating and drying, the thickness of the solid electrolyte layer was 5 μm.

[0142] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3, CMC and SBR were mixed in a mass ratio of 96.5:1.5:2, and then water was added and mixed evenly to obtain a mixed slurry with a solid content of 55%. The viscosity of the mixed slurry was 6000 mPa·s. The mixed slurry was coated on the negative electrode sheet. After coating and drying, the thickness of the solid electrolyte layer was 5 μm.

[0143] Comparative Example 2

[0144] Comparative Example 2 is substantially the same as Example 3, except that:

[0145] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3 and PVDF were mixed in a mass ratio of 99:1, and then NMP was added and mixed evenly to obtain a mixed slurry with a solid content of 70%. The viscosity of the mixed slurry was 7500 mPa·s. The mixed slurry was coated on the positive electrode sheet. After coating and drying, the thickness of the solid electrolyte layer was 5 μm.

[0146] Comparative Example 3

[0147] Comparative Example 3 is substantially the same as Example 3, except that:

[0148] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 (PO5)3, CMC and SBR were mixed in a mass ratio of 96.5:1.5:2, and then water was added and mixed evenly to obtain a mixed slurry with a solid content of 55%. The viscosity of the mixed slurry was 6000 mPa·s. The mixed slurry was coated on the negative electrode sheet. After coating and drying, the thickness of the solid electrolyte layer was 5 μm.

[0149] Comparative Example 4

[0150] Comparative Example 4 is substantially the same as Example 3, except that:

[0151] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225V 1.36 When (PO5)3 is plated on the positive electrode sheet, the sputtering power is 3.2kW;

[0152] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering power is 3.2kW.

[0153] Comparative Example 5

[0154] Comparative Example 5 is substantially the same as Example 3, except that:

[0155] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode sheet, the sputtering power is 5.8kW;

[0156] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering power is 5.8kW.

[0157] Comparative Example 6

[0158] Comparative Example 6 is substantially the same as Example 1, except that:

[0159] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the sputtering pressure is 0.2Pa;

[0160] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering gas pressure is 0.2Pa.

[0161] Comparative Example 7

[0162] Comparative Example 7 is substantially the same as Example 1, except that:

[0163] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36When (PO5)3 is plated on the positive electrode, the sputtering pressure is 0.8Pa;

[0164] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode sheet, the sputtering gas pressure is 0.8Pa.

[0165] Comparative Example 8

[0166] Comparative Example 8 is substantially the same as Example 3, except that:

[0167] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the background vacuum is 3×10 -5 Pa;

[0168] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode, the background vacuum is 3×10 -5 Pa.

[0169] Comparative Example 9

[0170] Comparative Example 9 is substantially the same as Example 3, except that:

[0171] In step S3 of preparing the composite positive electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the positive electrode, the background vacuum is 7×10 -5 Pa;

[0172] In step S3 of preparing the composite negative electrode sheet, the oxide solid electrolyte Li 1.3 Si 0.225 V 1.36 When (PO5)3 is plated on the negative electrode, the background vacuum is 7×10 -5 Pa.

[0173] Test Example 1 Electrochemical Performance Test

[0174] Use a battery internal resistance tester to test the internal resistance of the button cell.

[0175] The capacity of the button cell is tested under a current density of 0.5C. Gram capacity = capacity of the button cell / weight of the electrode active material.

[0176] The coin cell was charged and discharged for 50 cycles at a current density of 0.5C to test its cycling performance. The results are shown in Table 1. The gram capacity in Table 1 refers to the discharge gram capacity.

[0177] Table 1

[0178]

[0179] From Example 1 to Example 3, it can be seen that when the sputtering pressure increases from 0.3 Pa to 0.5 Pa, the first-week gram capacity of the positive electrode active material increases from 181.37 mAh / g to 189.34 mAh / g, and the gram capacity retention rate after 50 cycles increases from 92.00% to 95.98%. This is because as the sputtering pressure increases, the crystal size of the solid electrolyte in the solid electrolyte layer increases, reducing the side reactions between the solid electrolyte crystals and the positive and negative active materials; from Example 3 to Example 5, it can be seen that when the sputtering pressure increases from 0.5 Pa to 0.7 Pa, the first-week gram capacity of the positive electrode active material decreases from 189.34 mAh / g to 185.90 mAh / g, and the gram capacity retention rate after 50 cycles decreases from 95.98% to 94.19%. This is because as the crystal size continues to increase, the gap between the solid electrolyte crystals increases, thereby increasing the interface resistance; Comparative Examples 6 and 7 further verify these two trends.

[0180] It can be seen from Example 6, Example 7, and Example 3 that the sputtering power is increased from 3.5kW to 5.5kW, the size of the solid electrolyte crystals is increased, and the side reactions between the solid electrolyte crystals and the positive and negative active materials are reduced. The first-week gram capacity of the positive electrode active material is increased from 184.95mAh / g to 189.34mAh / g, and the gram capacity retention rate after 50 cycles is increased from 93.87% to 95.98%. Comparative Example 4 further verifies this trend. Comparative Example 5 further verifies that the sputtering power is increased. Compared with Example 3, the first-week gram capacity of the positive electrode active material is slightly decreased from 189.34mAh / g to 188.52mAh / g, and the gram capacity retention rate after 50 cycles is slightly decreased from 95.98% to 95.58%, indicating that the crystal size continues to increase, which is not conducive to the gram capacity and battery cycle performance.

[0181] It can be seen from Examples 9, 8 and 3 that the background vacuum is 6×10 -5 Pa increased to 5.0×10 - 5Pa, the first-week gram capacity of the positive electrode active material increased from 185.82 mAh / g to 189.34 mAh / g, and the gram capacity retention rate after 50 cycles increased from 94.37% to 95.98%. This is because after the background vacuum degree is improved, the crystals of the solid electrolyte in the solid electrolyte layer are more tightly bonded, reducing the internal resistance of the solid electrolyte layer. Comparative Example 9 further verifies this trend; Comparative Example 8 further improves the background vacuum degree to 3.0×10 -5 Pa, the first-week gram capacity improvement of the positive electrode active material is no longer obvious.

[0182] The composite positive electrode sheet and the composite negative electrode sheet of Comparative Example 1 are both coated with a solid electrolyte wet method. The interface resistance between the solid electrolyte crystals and between the solid electrolyte and the positive and negative electrode materials is large, so the first-week gram capacity, cycle performance, and cycle internal resistance increase rate of the positive electrode active material are not as good as those of Example 3 in which the solid electrolyte is coated by magnetron sputtering.

[0183] The composite positive electrode sheet of Comparative Example 2 is coated with a solid electrolyte by wet coating, and the composite negative electrode sheet is coated with a solid electrolyte by magnetron sputtering; the composite positive electrode sheet of Comparative Example 3 is coated with a solid electrolyte by magnetron sputtering, and the composite negative electrode sheet is coated with a solid electrolyte by wet coating. The first-week gram capacity, cycle performance, and cycle internal resistance increase rate of the positive electrode active material of these two methods are better than those of Comparative Example 1, but not as good as Example 3 in which the solid electrolyte is coated by magnetron sputtering.

[0184] The coin cell was charged and discharged at a current density of 0.5C, and the number of cycles required to achieve an 80% capacity retention rate was measured. When the coin cell reached an 80% capacity retention rate after repeated charge and discharge cycles, it was disassembled and inspected for the presence of lithium dendrites and powdery material on the surface of the composite negative electrode sheet. The results are shown in Table 2.

[0185] Table 2

[0186]

[0187] The composite negative electrode sheets of Comparative Examples 1 and 3 were coated with a solid electrolyte wet method. Disassembly of the batteries revealed the presence of powdery lithium dendrites on the surfaces of both composite negative electrode sheets. This was due to the solid electrolyte wet coating method used in Comparative Example 1, which allowed lithium dendrites to penetrate the solid electrolyte layer on the positive electrode sheet, leading to battery failure after approximately 320 cycles.

[0188] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0189] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for manufacturing a composite electrode sheet, characterized in that: The steps include: S1, mixing electrode materials, binder, conductive agent and solvent to obtain slurry; S2, coating the slurry on at least one surface of a current collector, drying and then rolling to obtain an electrode sheet; S3, forming a solid electrolyte layer on the surface of the electrode sheet coated with the slurry by a vacuum magnetron sputtering method; The process conditions of the vacuum magnetron sputtering method in step S3 include a background vacuum degree of 5×10 -5 ~6×10 -5 Pa, sputtering pressure 0.3~0.7Pa, sputtering power 3.5~5.5kW; the material of the solid electrolyte layer includes Li 1.3 Si 0.225 V 1.36 (PO5)3.

2. The production method according to claim 1, characterized in that The process conditions of the vacuum magnetron sputtering method in step S3 also include that the distance between the target material and the substrate is 20-50 mm.

3. The production method according to claim 1, characterized in that The thickness of the solid electrolyte layer is 5-6 μm.

4. The production method according to any one of claims 1 to 3, characterized in that The preparation method of the electrode material comprises the following steps: After the electrode active material is mixed with the solid electrolyte, ball milling, sintering, crushing and screening are sequentially performed to coat the surface of the electrode active material with the solid electrolyte to obtain the electrode material.

5. The production method according to claim 4, characterized in that: Include at least one of the following features: (1) The electrode active material includes a positive electrode active material; (2) The electrode active material includes a positive electrode active material, and the positive electrode active material includes LiCoO2, LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2 and NCA ternary materials; (3) The electrode active material includes a negative electrode active material; (4) The electrode active material includes a negative electrode active material, and the negative electrode active material includes one or more of metallic lithium, graphite, and silicon-carbon material; (5) The binder includes one or more of PVDF, CMC and SBR; (6) The conductive agent includes one or more of graphene, conductive carbon black, carbon nanotubes, Ketjen black and conductive graphite; (7) The solvent includes one or more of NMP and water; (8) The process conditions of the sintering treatment include a sintering temperature of 800-1000° C. and a sintering time of 1-3 h; (9) The sieve used in the screening process has an aperture of 200-250 mesh; (10) The D50 of the electrode material is 8 to 20 μm; (11) The solid content of the slurry is 30% to 76%; (12) The viscosity of the slurry is 3000~9000mPa·s; (13) The current collector includes one or more of aluminum foil and copper foil.

6. The manufacturing method according to claim 5, characterized in that: The mass ratio of the electrode active material to the solid electrolyte is (85-95): (5-15).

7. The production method according to any one of claims 1 to 3, characterized in that: The thickness of the electrode sheet is 123-155 μm.

8. A composite electrode sheet produced by the production method according to any one of claims 1 to 7.

9. A solid-state battery comprising the composite electrode sheet manufactured by the manufacturing method according to any one of claims 1 to 7 or the composite electrode sheet according to claim 8.

10. An electrical device comprising the solid-state battery according to claim 9.

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