All-solid-state battery and manufacturing method thereof

Abstract

The invention discloses an all-solid-state battery and a manufacturing method thereof. The all-solid-state battery comprises an all-solid-state positive electrode, an all-solid-state negative electrode, and a first sulfide electrolyte membrane and a second sulfide electrolyte membrane which are positioned between the all-solid-state positive electrode and the all-solid-state negative electrode, the first sulfide electrolyte membrane is located on the side, close to the all-solid-state positive electrode, of the second sulfide electrolyte membrane, the first sulfide electrolyte membrane makes contact with the all-solid-state positive electrode, the second sulfide electrolyte membrane makes contact with the all-solid-state negative electrode, and the first sulfide electrolyte membrane comprises crystalline state sulfide electrolyte. By combining the hardness difference between the crystalline sulfide electrolyte and the amorphous sulfide electrolyte, the crystalline electrolyte membrane is tightly attached to the all-solid-state positive electrode with small volume deformation, and the glassy electrolyte membrane is tightly attached to the all-solid-state negative electrode with large volume deformation. The interface impedance of the all-solid-state battery is effectively reduced by constructing the double-layer sulfide electrolyte membrane.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and more specifically, to an all-solid-state battery and a method for manufacturing the same. Background Art

[0002] Since their mass production, lithium-ion batteries have played a huge role in industries such as consumer electronics, electric vehicles, and energy storage and have changed the way people live. However, traditional liquid lithium-ion batteries still face shortcomings such as energy density approaching the theoretical limit and poor safety.

[0003] In order to solve the above problems, many new high energy density and high safety battery systems have been widely studied, among which sulfide all-solid-state batteries are highly anticipated. However, the commercial development of all-solid-state batteries still faces scientific challenges in material research and development and technical challenges in process amplification. One of the important challenges is the large interface impedance inside the battery cell, which will undoubtedly lead to increased polarization of the battery cell and poor cycle performance.

[0004] The solution to the problem of excessive interface impedance in all-solid-state batteries in the prior art is to apply ultra-high pressure, such as using a special mold to pressurize to a pressure greater than 500MPa. This method reduces the interface impedance under certain conditions, but the additional pressure device will undoubtedly reduce the energy density of the battery cell. In addition, in the prior art, a polymer electrolyte membrane layer is introduced at the interface between the negative electrode and the sulfide electrolyte to reduce the interface impedance. The introduced polymer electrolyte membrane layer is relatively soft and can improve the interface contact to a certain extent, but the low ionic conductivity of the polymer electrolyte at room temperature will significantly reduce the rate performance of the battery cell. In severe cases, it will cause the battery cell to short-circuit due to lithium deposition at a low rate.

[0005] Therefore, it is necessary to provide an all-solid-state battery and a method for manufacturing the same that can reduce the interface impedance without reducing the energy density of the battery cell and ensure the rate performance of the battery cell. Summary of the invention

[0006] In view of this, the present invention provides an all-solid-state battery and a method for manufacturing the same, which are used to reduce the interface impedance while ensuring that the energy density of the battery cell is not reduced and the rate performance of the battery cell is guaranteed.

[0007] On the one hand, the present invention provides an all-solid-state battery, comprising an all-solid-state positive electrode and an all-solid-state negative electrode, and a first sulfide electrolyte membrane and a second sulfide electrolyte membrane located between the all-solid-state positive electrode and the all-solid-state negative electrode, the first sulfide electrolyte membrane being located on a side of the second sulfide electrolyte membrane close to the all-solid-state positive electrode, the first sulfide electrolyte membrane being at least partially in contact with the all-solid-state positive electrode, and the second sulfide electrolyte membrane being at least partially in contact with the all-solid-state negative electrode, wherein the first sulfide electrolyte membrane comprises a crystalline sulfide electrolyte, and the second sulfide electrolyte membrane comprises an amorphous sulfide electrolyte.

[0008] Optionally, the crystalline sulfide electrolyte includes at least one of a crystalline lithium germanium phosphorus sulfur electrolyte, a crystalline lithium silicon phosphorus sulfur chlorine electrolyte and a crystalline lithium boron sulfur electrolyte.

[0009] The crystalline sulfide electrolyte has high electrical conductivity and high hardness. The present invention utilizes the high electrical conductivity of crystalline electrolytes such as crystalline lithium germanium phosphorus sulfur electrolyte, crystalline lithium silicon phosphorus sulfur chlorine electrolyte and crystalline lithium boron sulfur electrolyte to reduce the impedance of the all-solid-state battery.

[0010] Optionally, a particle size D50 of the crystalline sulfide electrolyte in the first sulfide electrolyte membrane is 0.1 μm to 6 μm; and / or a thickness of the first sulfide electrolyte membrane is 15 μm to 100 μm.

[0011] Optionally, the particle size D50 of the crystalline sulfide electrolyte in the first sulfide electrolyte membrane can be 0.1μm, 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm or 6μm, or any value between 0.1μm and 6μm. Too small or too large a particle size of the crystalline sulfide electrolyte will lead to a decrease in battery performance. If the particle size is too small, the increase in specific surface area will lead to an increase in the particle size side reaction of the active material and the crystalline sulfide electrolyte, generating byproducts with low ionic conductivity, and the interface impedance will increase, resulting in poor battery performance; if the electrolyte particle size is too large (more than 6μm), less electrolyte will be attached to the surface of the active material, the ion conductive network will deteriorate, and the interface impedance will increase, which will also lead to poor battery performance. The particle size D50 is distributed in the range of 0.1μm to 6μm, which can improve battery performance.

[0012] Optionally, the thickness of the first sulfide electrolyte membrane can be 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm, or any value between 15 μm and 100 μm. If the thickness of the first sulfide electrolyte membrane is greater than 100 μm, the lithium ion transmission path becomes longer and the rate performance becomes worse. If the first sulfide electrolyte membrane is too thin, less than 15 μm, the diameter growth of the negative electrode side can easily pierce the electrolyte membrane and cause a short circuit between the positive and negative electrodes.

[0013] Optionally, the first sulfide electrolyte membrane further includes a non-polar binder and a non-polar oil-based solvent, wherein:

[0014] The non-polar binder includes at least one of styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene type block copolymer, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and ethylene-propylene rubber;

[0015] And / or, the non-polar oil-based solvent includes at least one of an organic ester organic solvent, an aromatic hydrocarbon organic solvent, an ether organic solvent and a ketone organic solvent.

[0016] It is understandable that the electrolyte in the first sulfide electrolyte membrane is a sulfide electrolyte, which cannot come into contact with polar solvents (side reactions often occur, causing the electrolyte structure to collapse or the conductivity to drop significantly). Therefore, non-polar solvents are often used for slurry coating. The above-mentioned non-polar binders are all binders suitable for non-polar solvent systems and suitable for use in sulfide solid-state batteries.

[0017] Similarly, the electrolyte in the first sulfide electrolyte membrane is a sulfide electrolyte, which cannot come into contact with polar solvents (side reactions often occur, causing the electrolyte structure to collapse or a significant decrease in conductivity). Therefore, non-polar solvents are often used for slurry coating to ensure industrial slurry coating and excellent battery performance.

[0018] Optionally, the binder percentage of the first sulfide electrolyte membrane is greater than 0.5% and less than 6%. As an inactive material, the binder itself does not conduct lithium ions or electrons. The higher the content, the more disadvantageous it is for the pole piece. However, in order to make the pole piece have better adhesion, the binder needs to be added. The binder percentage is greater than 0.5% and less than 6%, which can ensure the best adhesion performance at a lower ratio.

[0019] Optionally, the amorphous sulfide electrolyte includes at least one of a glassy sulfide electrolyte and a glass-ceramic sulfide electrolyte, wherein:

[0020] Glassy sulfide electrolytes include Li 2 S and P 2 S 5 Glassy electrolytes of electrolytes composed of different molar ratios and halogen-doped lithium phosphorus-sulfur systems;

[0021] The glass-ceramic sulfide electrolyte includes Li sintered at a high temperature of 600°C to 800°C. 2 S and P 2 S 5 Electrolytes composed of different molar ratios, glass-ceramic electrolytes of halogen-doped lithium phosphorus-sulfur systems, and argyrodite-type glass-ceramic electrolytes sintered at low temperatures of 150° C. to 300° C.

[0022] It is understandable that the amorphous sulfide electrolyte has lower ionic conductivity than the crystalline sulfide electrolyte, but it has an advantage that it is softer in texture. When used on the negative electrode side with large volume expansion and contraction, it can alleviate the volume expansion and contraction and improve the interface contact. Glassy sulfide electrolytes and glass-ceramic sulfide electrolytes include a variety of subdivided amorphous electrolytes, which can slightly improve the interface contact.

[0023] Optionally, the Young's modulus of the second sulfide electrolyte membrane is 5 GPa to 20 GPa;

[0024] The particle size D50 of the amorphous sulfide electrolyte of the second sulfide electrolyte membrane is 0.1 μm to 6 μm;

[0025] And / or, the second sulfide electrolyte membrane has a thickness of 10 μm to 100 μm.

[0026] It should be noted that the sulfide electrolyte with a high Young's modulus has a poor effect on inhibiting the volume expansion and contraction on the negative electrode side, but has a high ionic conductivity, while the sulfide electrolyte with a low Young's modulus has a good effect on inhibiting the volume expansion and contraction on the negative electrode side, but has a low ionic conductivity. Therefore, it is necessary to take into account the ionic conductivity while ensuring the appropriate Young's modulus. The Young's modulus of the second sulfide electrolyte membrane is 5Gpa to 20GPa, which can take into account the ionic conductivity.

[0027] Optionally, the particle size D50 of the amorphous sulfide electrolyte in the second sulfide electrolyte membrane can be 0.1μm, 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm or 6μm, or any value between 0.1μm and 6μm. The particle size D50 is distributed in this interval because both too small and too large electrolyte particle sizes will lead to decreased battery performance. If the particle size is too small, the increased specific surface area will lead to increased side reactions between the active material and the sulfide electrolyte, generating byproducts with low ionic conductivity, and the increased interface impedance will cause the battery performance to deteriorate; if the electrolyte is too large (more than 6μm), the amount of electrolyte attached to the surface of the active material will decrease, the ion conductive network will deteriorate, and the increased interface impedance will also cause the battery performance to deteriorate. The particle size D50 is distributed in the range of 0.1μm to 6μm, which can improve battery performance.

[0028] Optionally, the thickness of the second sulfide electrolyte membrane can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm, or any value between 10 μm and 100 μm. If the thickness of the second sulfide electrolyte membrane is greater than 100 μm, the lithium ion transmission path becomes longer and the rate performance becomes worse. If the electrolyte membrane is too thin and is less than 10 μm, the diameter growth of the negative electrode side is easy to pierce the electrolyte membrane and cause a short circuit between the positive and negative electrodes.

[0029] Optionally, the second sulfide electrolyte membrane further includes a non-polar binder and a non-polar oil-based solvent, wherein:

[0030] The non-polar binder includes at least one of styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene type block copolymer, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and ethylene-propylene rubber;

[0031] The non-polar oil-based solvent includes at least one of an organic ester organic solvent, an aromatic hydrocarbon organic solvent, an ether organic solvent and a ketone organic solvent.

[0032] It is understandable that the electrolyte in the second sulfide electrolyte membrane is a sulfide electrolyte, which cannot come into contact with polar solvents (side reactions often occur, causing the electrolyte structure to collapse or a significant decrease in conductivity). Therefore, non-polar solvents are often used for slurry coating. The above-mentioned non-polar binders are all suitable for non-polar solvent systems and are suitable for use in sulfide solid-state batteries.

[0033] Similarly, the electrolyte in the second sulfide electrolyte membrane is a sulfide electrolyte, which cannot come into contact with polar solvents (side reactions often occur, causing the electrolyte structure to collapse or a significant decrease in conductivity). Therefore, the above-mentioned non-polar oil-based solvents are often used for slurry coating to ensure industrial slurry coating and excellent battery performance.

[0034] Optionally, the binder percentage of the second sulfide electrolyte membrane is greater than 0.5% and less than 6%. As an inactive material, the binder itself does not conduct lithium ions or electrons. The higher the content, the more disadvantageous it is for the pole piece. However, in order to make the pole piece have better adhesion, the binder needs to be added. The binder percentage is greater than 0.5% and less than 6%, which can ensure the best adhesion performance at a lower ratio.

[0035] Optionally, the all-solid-state positive electrode comprises positive electrode active particles, and the all-solid-state negative electrode comprises negative electrode active materials, wherein:

[0036] The positive electrode active particles include at least one of high nickel ternary, lithium iron phosphate, lithium iron manganese phosphate, lithium-rich manganese-based positive electrode and lithium-free positive electrode;

[0037] The negative electrode active material includes at least one of silicon element, silicon-carbon material, silicon-oxygen material, graphite material and lithium metal.

[0038] On the other hand, the present invention also provides a method for manufacturing an all-solid-state battery, which is used to manufacture the above-mentioned all-solid-state battery, comprising the steps of:

[0039] Making all-solid-state positive electrode;

[0040] Making an all-solid-state negative electrode;

[0041] preparing a second sulfide electrolyte membrane comprising an amorphous sulfide electrolyte, and coating or transferring the second sulfide electrolyte membrane to the surface of the all-solid-state negative electrode, so that the second sulfide electrolyte membrane is combined with the all-solid-state negative electrode;

[0042] A first sulfide electrolyte membrane comprising a crystalline sulfide electrolyte is prepared, and the first sulfide electrolyte membrane is coated or transferred onto the surface of a second sulfide electrolyte membrane to form a combined structure of a stacked first sulfide electrolyte membrane, a second sulfide electrolyte membrane and an all-solid-state negative electrode;

[0043] The all-solid-state positive electrode is placed on the side of the first sulfide electrolyte membrane away from the second sulfide electrolyte membrane to complete the stacking and form a battery cell of the all-solid-state battery.

[0044] On the other hand, the present invention also provides a method for manufacturing an all-solid-state battery, which is used to manufacture the above-mentioned all-solid-state battery, comprising the steps of:

[0045] Making all-solid-state positive electrode;

[0046] Making an all-solid-state negative electrode;

[0047] preparing a second sulfide electrolyte membrane comprising an amorphous sulfide electrolyte, and coating or transferring the second sulfide electrolyte membrane to the surface of the all-solid-state negative electrode, so that the second sulfide electrolyte membrane is combined with the all-solid-state negative electrode;

[0048] Prepare a first sulfide electrolyte membrane including a crystalline sulfide electrolyte, and apply or transfer the first sulfide electrolyte membrane to the surface of the all-solid-state positive electrode, so that the first sulfide electrolyte membrane is combined with the all-solid-state positive electrode;

[0049] The first sulfide electrolyte membrane and the second sulfide electrolyte membrane are bonded together and stacked to form a battery cell of the all-solid-state battery.

[0050] Compared with the prior art, the all-solid-state battery and the manufacturing method thereof provided by the present invention achieve at least the following beneficial effects:

[0051] The present invention combines the hardness difference between the crystalline sulfide electrolyte and the amorphous sulfide electrolyte. The crystalline electrolyte membrane is closely attached to the all-solid-state positive electrode with a smaller volume deformation. The high electrical conductivity of the crystalline electrolyte can reduce the impedance of the all-solid-state battery. The amorphous electrolyte membrane is closely attached to the all-solid-state negative electrode with a larger volume deformation. Compared with the crystalline sulfide electrolyte, the amorphous sulfide electrolyte has a lower ionic conductivity, but its texture is softer. When used on the negative electrode side with a larger volume expansion and contraction, it can alleviate the volume expansion and contraction and improve the interface contact. The present invention effectively reduces the interface impedance of the all-solid-state battery by constructing a double-layer sulfide electrolyte membrane.

[0052] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0053] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0055] Figure 1 is a cross-sectional view of an all-solid-state battery provided by the present invention;

[0056] Figure 2 It is a flow chart of a method for manufacturing an all-solid-state battery provided by the present invention;

[0057] Figure 3 This is a flow chart of another method for manufacturing an all-solid-state battery provided by the present invention. DETAILED DESCRIPTION

[0058] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0059] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0060] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0061] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0062] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0063] Combination Figure 1 and Figure 2 The present invention provides a method for manufacturing an all-solid-state battery, which is used to manufacture an all-solid-state battery, comprising the steps of:

[0064] S101, preparing an all-solid-state positive electrode 10;

[0065] S102, preparing an all-solid-state negative electrode 20;

[0066] S103, preparing a second sulfide electrolyte membrane 40 including an amorphous sulfide electrolyte, and coating or transferring the second sulfide electrolyte membrane 40 to the surface of the all-solid-state negative electrode 20, so that the second sulfide electrolyte membrane 40 is combined with the all-solid-state negative electrode 20;

[0067] S104, preparing a first sulfide electrolyte membrane 30 including a crystalline sulfide electrolyte, and coating or transferring the first sulfide electrolyte membrane 30 onto a surface of a second sulfide electrolyte membrane 40 to form a combined structure of a stacked first sulfide electrolyte membrane 30, a second sulfide electrolyte membrane 40, and an all-solid-state negative electrode 20;

[0068] S105 , placing the all-solid-state positive electrode 10 on a side of the first sulfide electrolyte membrane 30 away from the second sulfide electrolyte membrane 40 , completing the stacking to form a battery cell of the all-solid-state battery.

[0069] Combination Figure 1 and Figure 3 The present invention also provides a method for manufacturing an all-solid-state battery, which is used to manufacture an all-solid-state battery, comprising the steps of:

[0070] S201, preparing an all-solid-state positive electrode 10;

[0071] S202, preparing an all-solid-state negative electrode 20;

[0072] S203, preparing a second sulfide electrolyte membrane 40 including an amorphous sulfide electrolyte, and coating or transferring the second sulfide electrolyte membrane 40 to the surface of the all-solid-state negative electrode 20, so that the second sulfide electrolyte membrane 40 is combined with the all-solid-state negative electrode 20;

[0073] S204, preparing a first sulfide electrolyte membrane 30 including a crystalline sulfide electrolyte, and coating or transferring the first sulfide electrolyte membrane 30 to the surface of the all-solid-state positive electrode 10, so that the first sulfide electrolyte membrane 30 is combined with the all-solid-state positive electrode 10;

[0074] S205 , bonding the first sulfide electrolyte membrane 30 and the second sulfide electrolyte membrane 40 to complete stacking to form a battery cell of the all-solid-state battery.

[0075] Specifically, the all-solid-state battery can be manufactured by referring to the following embodiments.

[0076] Example 1

[0077] Layered nickel-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811, provided by Hefei Guoxuan High-tech) as active material and sulfide electrolyte Li 6 PS 5 Cl and binder styrene-butadiene-styrene block copolymer (SBS) were mixed in a mass ratio of 80:18:2, coated and dried to obtain a composite positive electrode sheet.

[0078] Pure micron silicon negative electrode (provided by Shenzhen Beite Rui) was used as the active material and mixed with binder polyvinylidene fluoride (PVDF) in a mass ratio of 99:1, and then the slurry was coated and dried to obtain a composite negative electrode sheet.

[0079] The glassy sulfide electrolyte Li 3 PS 4 After being mixed with the binder SBS in a mass ratio of 96:4 and adjusted to a solid content of 70%, it is coated on the surface of the composite silicon negative electrode. The coating thickness is controlled so that the thickness of the second sulfide electrolyte membrane (hereinafter referred to as sulfide electrolyte membrane II) is 20 μm (after drying), so that the sulfide electrolyte membrane II and the composite negative electrode are combined.

[0080] Then the crystalline sulfide electrolyte Li 6 PS 5 Cl and binder SBS are mixed in a mass ratio of 96:4 and adjusted to a solid content of 70% and coated on the surface of sulfide electrolyte membrane II. The coating thickness is controlled so that the thickness of the first sulfide electrolyte membrane (hereinafter referred to as sulfide electrolyte membrane I) is 60 μm (after drying), and finally a double-layer electrolyte sulfide electrolyte membrane I and sulfide electrolyte membrane II are combined with a composite negative electrode.

[0081] The all-solid-state composite positive electrode plate is placed on the side of the sulfide electrolyte membrane I. After the stacking assembly is completed, the overall four-layer isostatic pressing is performed at 400MPa to obtain a battery cell. The battery cell test external pressure is 5MPa. The test process is to activate it at 0.1C for 2 cycles and then start 1C cycling for 100 cycles. After that, the capacity retention rate is calculated and the impedance is tested by the electrochemical workstation and the interface transfer impedance (Rct) is obtained by fitting.

[0082] Example 2

[0083] Layered nickel-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 As active material with sulfide electrolyte Li 6 PS 5 Cl and binder styrene-butadiene-styrene block copolymer (SBS) were mixed in a mass ratio of 80:18:2, coated and dried to obtain a composite positive electrode sheet.

[0084] Pure micron silicon negative electrode is used as an active material and a binder polyvinylidene fluoride (PVDF) is mixed in a mass ratio of 99:1, and then the mixture is coated and dried to obtain a composite negative electrode sheet.

[0085] The glassy sulfide electrolyte Li 3 PS 4 After being mixed with the binder SBS in a mass ratio of 96:4 and adjusted to a solid content of 70%, it is coated on the surface of the composite silicon negative electrode. The coating thickness is controlled so that the thickness of the sulfide electrolyte membrane II is 10 μm (after drying), so that the sulfide electrolyte membrane II and the composite negative electrode are combined.

[0086] Then the crystalline sulfide electrolyte Li 6 PS 5 Cl and binder SBS were mixed in a mass ratio of 96:4 and adjusted to a solid content of 70% and coated on the surface of sulfide electrolyte membrane II. The coating thickness was controlled so that the thickness of sulfide electrolyte membrane I was 70 μm (after drying), and finally a double-layer electrolyte sulfide electrolyte membrane I and sulfide electrolyte membrane II were combined with a composite negative electrode.

[0087] The all-solid-state composite positive electrode plate is placed on the side of the sulfide electrolyte membrane I. After the stacking assembly is completed, the overall four-layer isostatic pressing is performed at 400MPa to obtain a battery cell. The battery cell test external pressure is 5MPa. The test process is to activate it at 0.1C for 2 cycles and then start 1C cycling for 100 cycles. After that, the capacity retention rate is calculated and the impedance is tested by the electrochemical workstation and the interface transfer impedance (Rct) is obtained by fitting.

[0088] Example 3

[0089] Layered nickel-rich LiNi 0.8 Co 0.1 Mn 0.1O 2 (NCM811, Hefei Guoxuan High-tech) as active material and sulfide electrolyte Li 6 PS 5 Cl and binder styrene-butadiene-styrene block copolymer (SBS) were mixed in a mass ratio of 80:18:2, coated and dried to obtain a composite positive electrode sheet.

[0090] Pure micron silicon negative electrode (Shenzhen BYD) was used as the active material and mixed with binder polyvinylidene fluoride (PVDF) in a mass ratio of 99:1, and then the mixture was coated and dried to obtain a composite negative electrode sheet.

[0091] The glassy sulfide electrolyte Li 3 PS 4 After being mixed with the binder SBS in a mass ratio of 96:4 and adjusted to a solid content of 70%, it is coated on the surface of the composite silicon negative electrode. The coating thickness is controlled so that the thickness of the sulfide electrolyte membrane II is 40 μm (after drying), so that the sulfide electrolyte membrane II and the composite negative electrode are combined.

[0092] Then the crystalline sulfide electrolyte Li 6 PS 5 Cl and binder SBS were mixed in a mass ratio of 96:4 and adjusted to a solid content of 70% and coated on the surface of sulfide electrolyte membrane II. The coating thickness was controlled so that the thickness of sulfide electrolyte membrane I was 40 μm (after drying), and finally a double-layer electrolyte sulfide electrolyte membrane I and sulfide electrolyte membrane II were combined with a composite negative electrode.

[0093] The all-solid-state composite positive electrode plate is placed on the side of the sulfide electrolyte membrane I. After the stacking assembly is completed, the overall four-layer isostatic pressing is performed at 400MPa to obtain a battery cell. The battery cell test external pressure is 5MPa. The test process is to activate it at 0.1C for 2 cycles and then start 1C cycling for 100 cycles. After that, the capacity retention rate is calculated and the impedance is tested by the electrochemical workstation and the interface transfer impedance (Rct) is obtained by fitting.

[0094] In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples are provided:

[0095] Comparative Example 1

[0096] Layered nickel-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811, provided by Hefei Guoxuan High-tech) as active material and sulfide electrolyte Li 6 PS 5 Cl and binder styrene-butadiene-styrene block copolymer (SBS) were mixed in a mass ratio of 80:18:2, coated and dried to obtain a composite positive electrode sheet.

[0097] Pure micron silicon negative electrode (provided by Shenzhen Beite Rui) was used as the active material and mixed with binder polyvinylidene fluoride (PVDF) in a mass ratio of 99:1, and then the slurry was coated and dried to obtain a composite negative electrode sheet.

[0098] The crystalline sulfide electrolyte Li 6 PS 5 Cl and binder SBS were mixed in a mass ratio of 96:4 and adjusted to a solid content of 70% and coated on the surface of the composite silicon negative electrode. The coating thickness was controlled so that the thickness of the sulfide electrolyte membrane I was 80 μm (after drying), so that the sulfide electrolyte I and the composite negative electrode were combined.

[0099] The all-solid-state composite positive electrode plate is placed on the side of the sulfide electrolyte membrane I. After the stacking assembly is completed, the overall four-layer isostatic pressing is performed at 400MPa to obtain a battery cell. The battery cell test external pressure is 5MPa. The test process is to activate it at 0.1C for 2 cycles and then start 1C cycling for 100 cycles. After that, the capacity retention rate is calculated and the impedance is tested by the electrochemical workstation and the interface transfer impedance (Rct) is obtained by fitting.

[0100] Comparative Example 2

[0101] Layered nickel-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811, Hefei Guoxuan High-tech) as active material and sulfide electrolyte Li 6 PS 5 Cl and binder styrene-butadiene-styrene block copolymer (SBS) were mixed in a mass ratio of 80:18:2, coated and dried to obtain a composite positive electrode sheet.

[0102] Pure micron silicon negative electrode (Shenzhen BYD) was used as the active material and mixed with binder polyvinylidene fluoride (PVDF) in a mass ratio of 99:1, and then the mixture was coated and dried to obtain a composite negative electrode sheet.

[0103] The glassy sulfide electrolyte Li 3 PS 4 After being mixed with the binder SBS in a mass ratio of 96:4 and adjusted to a solid content of 70%, it is coated on the surface of the composite silicon negative electrode. The coating thickness is controlled so that the thickness of the sulfide electrolyte membrane II is 80 μm (after drying), so that the sulfide electrolyte membrane II and the composite negative electrode are combined.

[0104] The all-solid-state composite positive electrode plate is placed on the sulfide electrolyte membrane II side. After the stacking assembly is completed, the overall four-layer isostatic pressing is performed at 400MPa to obtain a battery cell. The battery cell test external pressure is 5MPa. The test process is to activate it at 0.1C for 2 cycles and then start 1C cycling for 100 cycles. After that, the capacity retention rate is calculated and the impedance is tested by the electrochemical workstation and the interface transfer impedance (Rct) is obtained by fitting.

[0105] Table 1. Test table of battery cells of embodiments and comparative examples

[0106]

[0107] It can be seen from Table 1 that in Comparative Example 1, there is only one type of battery cell electrolyte membrane, which is the crystalline sulfide electrolyte membrane I with high ionic conductivity. Due to its high ionic conductivity, the optimal discharge capacity at 0.1C in the first cycle is 200mAh / g. However, the crystalline sulfide electrolyte membrane I has a high Young's modulus and poor resistance to negative electrode deformation. After 100 cycles at 1C, the discharge capacity is 136mAh / g, and the capacity retention rate is 78%, both of which are the worst. The interface transfer impedance is 647Ω, which is also the highest. In Comparative Example 2, there is only one type of cell electrolyte membrane, which is a glassy sulfide electrolyte membrane II with low ionic conductivity. Due to its low ionic conductivity, the first cycle 0.1C discharge capacity is only 188mAh / g at the lowest. After 100 cycles of 1C, the discharge capacity is 128mAh / g, the capacity retention rate is 534%, and the interface transfer impedance is 534Ω. The Young's modulus of the glassy sulfide electrolyte membrane II is low and the negative electrode deformation resistance is good, but the electrolyte grain boundary impedance is large, so the cycle stability is not optimal. In Example 1, the cell electrolyte membrane is a double-layer membrane of a crystalline sulfide electrolyte membrane I with high ionic conductivity and a glassy sulfide electrolyte membrane II with low ionic conductivity. Due to the consideration of high ionic conductivity and low Young's modulus, the first cycle 0.1C discharge capacity is 198mAh / g, and the discharge capacity after 100 cycles of 1C is 156mAh / g, the capacity retention rate is 92%, the capacity retention rate is optimal, and the interface transfer impedance is 202Ω, which is also the minimum.

[0108] From Comparative Example 1 and Example 1, it can be seen that the battery capacity retention rate of using high Young's modulus crystalline sulfide electrolyte membrane I alone is poor and the interface impedance after cycling is high; from Comparative Example 2 and Example 1, it can be seen that the battery capacity of using low Young's modulus glassy sulfide electrolyte membrane II alone is low, because the electrolyte itself has a large grain boundary impedance, so the capacity retention rate is low and the interface impedance after cycling is high.

[0109] From Example 1, Example 2 and Example 3, the difference in thickness of the double-layer membranes of crystalline sulfide electrolyte membrane I and glassy sulfide electrolyte membrane II with low ionic conductivity affects the performance of the battery cell as follows: the optimal thicknesses of crystalline sulfide electrolyte membrane I and glassy sulfide electrolyte membrane II are 60 μm and 20 μm, respectively (Example 1), which can maximize the balance between ionic conductivity and low Young's modulus to inhibit the volume expansion and contraction of the silicon negative electrode; when the thickness of crystalline sulfide electrolyte membrane I is increased to 70 μm and the thickness of glassy sulfide electrolyte membrane II is reduced to 10 μm (Example 2), it can be clearly found that the excessively thin glassy sulfide electrolyte membrane II leads to an increase in the interface impedance caused by the volume change on the negative electrode side; when the thickness of crystalline sulfide electrolyte membrane I is reduced to 40 μm and the thickness of glassy sulfide electrolyte membrane II is increased to 40 μm (Example 3), it can be clearly found that the reduction in the content of high ionic conductivity crystalline sulfide electrolyte membrane I and the increase in low ionic conductivity glassy sulfide electrolyte membrane II also increase the interface impedance of the battery cell.

[0110] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. An all-solid-state battery, characterized in that: It includes an all-solid-state positive electrode and an all-solid-state negative electrode, and a first sulfide electrolyte membrane and a second sulfide electrolyte membrane located between the all-solid-state positive electrode and the all-solid-state negative electrode, wherein the first sulfide electrolyte membrane is located on a side of the second sulfide electrolyte membrane close to the all-solid-state positive electrode, the first sulfide electrolyte membrane is at least partially in contact with the all-solid-state positive electrode, and the second sulfide electrolyte membrane is at least partially in contact with the all-solid-state negative electrode, wherein the first sulfide electrolyte membrane includes a crystalline sulfide electrolyte, and the second sulfide electrolyte membrane includes an amorphous sulfide electrolyte.

2. The all-solid-state battery according to claim 1, characterized in that: The crystalline sulfide electrolyte includes at least one of a crystalline lithium germanium phosphorus sulfur electrolyte, a crystalline lithium silicon phosphorus sulfur chlorine electrolyte and a crystalline lithium boron sulfur electrolyte.

3. The all-solid-state battery according to claim 1, characterized in that: The particle size D50 of the crystalline sulfide electrolyte in the first sulfide electrolyte membrane is 0.1 μm to 6 μm; And / or, the first sulfide electrolyte membrane has a thickness of 15 μm to 100 μm.

4. The all-solid-state battery according to claim 1, characterized in that: The first sulfide electrolyte membrane further comprises a non-polar binder and a non-polar oil-based solvent, wherein: The non-polar binder includes at least one of styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene type block copolymer, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and ethylene-propylene rubber; And / or, the non-polar oil-based solvent includes at least one of an organic ester organic solvent, an aromatic hydrocarbon organic solvent, an ether organic solvent and a ketone organic solvent.

5. The all-solid-state battery according to claim 1, characterized in that: The amorphous sulfide electrolyte includes at least one of a glassy sulfide electrolyte and a glass-ceramic sulfide electrolyte, wherein: The glassy sulfide electrolyte includes an electrolyte composed of Li2S and P2S5 in different molar ratios and a glassy electrolyte of a halogen-doped lithium phosphorus-sulfur system; The glass-ceramic sulfide electrolyte includes an electrolyte composed of Li2S and P2S5 in different molar ratios obtained by sintering at a high temperature of 600°C to 800°C, a glass-ceramic electrolyte of a halogen-doped lithium phosphorus-sulfur system, and an argyrodite-type glass-ceramic electrolyte obtained by sintering at a low temperature of 150°C to 300°C.

6. The all-solid-state battery according to claim 1, characterized in that: The Young's modulus of the second sulfide electrolyte membrane is 5 GPa to 20 GPa; The particle size D50 of the amorphous sulfide electrolyte of the second sulfide electrolyte membrane is 0.1 μm to 6 μm; And / or, the second sulfide electrolyte membrane has a thickness of 10 μm to 100 μm.

7. The all-solid-state battery according to claim 1, characterized in that: The second sulfide electrolyte membrane further comprises a non-polar binder and a non-polar oil-based solvent, wherein: The non-polar binder includes at least one of styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene type block copolymer, styrene-butadiene rubber, nitrile rubber, chloroprene rubber and ethylene-propylene rubber; The non-polar oil-based solvent includes at least one of an organic ester organic solvent, an aromatic hydrocarbon organic solvent, an ether organic solvent and a ketone organic solvent.

8. The all-solid-state battery according to claim 1, characterized in that: The all-solid positive electrode comprises positive electrode active particles, and the all-solid negative electrode comprises negative electrode active materials, wherein: The positive electrode active particles include at least one of high nickel ternary, lithium iron phosphate, lithium iron manganese phosphate, lithium-rich manganese-based positive electrode and lithium-free positive electrode; The negative electrode active material includes at least one of silicon, silicon-carbon material, silicon-oxygen material, graphite material and lithium metal.

9. A method for manufacturing an all-solid-state battery, used for manufacturing the all-solid-state battery according to any one of claims 1 to 8, characterized in that: Includes steps: Making all-solid-state positive electrode; Making an all-solid-state negative electrode; Making a second sulfide electrolyte membrane comprising an amorphous sulfide electrolyte, and coating or transferring the second sulfide electrolyte membrane to the surface of the all-solid-state negative electrode, so that the second sulfide electrolyte membrane is combined with the all-solid-state negative electrode; A first sulfide electrolyte membrane comprising a crystalline sulfide electrolyte is prepared, and the first sulfide electrolyte membrane is coated or transferred onto the surface of the second sulfide electrolyte membrane to form a combined structure of a stacked first sulfide electrolyte membrane, a second sulfide electrolyte membrane and an all-solid-state negative electrode; The all-solid-state positive electrode is placed on a side of the first sulfide electrolyte membrane away from the second sulfide electrolyte membrane to complete stacking to form a battery cell of the all-solid-state battery.

10. A method for manufacturing an all-solid-state battery, used for manufacturing the all-solid-state battery according to any one of claims 1 to 8, characterized in that: Includes steps: Making all-solid-state positive electrode; Making an all-solid-state negative electrode; Making a second sulfide electrolyte membrane comprising an amorphous sulfide electrolyte, and coating or transferring the second sulfide electrolyte membrane to the surface of the all-solid-state negative electrode, so that the second sulfide electrolyte membrane is combined with the all-solid-state negative electrode; Making a first sulfide electrolyte membrane comprising a crystalline sulfide electrolyte, and coating or transferring the first sulfide electrolyte membrane to the surface of the all-solid-state positive electrode, so that the first sulfide electrolyte membrane is combined with the all-solid-state positive electrode; The first sulfide electrolyte membrane and the second sulfide electrolyte membrane are bonded together to complete stacking to form a battery cell of the all-solid-state battery.

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