Glue solution for battery, electrode plate, diaphragm combination body, battery and preparation method thereof

Abstract

The invention provides a glue solution for a battery, an electrode plate, a diaphragm combination body, the battery and a preparation method of the battery, and relates to the field of all-solid-state batteries. The glue solution for the battery comprises a first binder, a second binder and a first solvent, the density of the first binder is smaller than that of the second binder, and the solubility of the first binder in the first solvent is larger than that of the second binder in the first solvent. The glue solution can be used in a battery positive plate and a battery negative plate, the glue solution comprises the first binder and the second binder which are different in density and solubility, and in the process of preparing the positive plate and the negative plate, the second binder can be settled and accumulated on one side close to a current collector, so that the current collector is prevented from being damaged. The first binder accumulates on the side away from the current collector with the volatilization of the first solvent. The first binder and the second binder are located on the two opposite sides of the active layer respectively and are similar to a sandwich shape, and the mechanical performance and the cycling stability of the electrode are improved.

Description

Technical Field

[0001] The present application relates to the field of all-solid-state batteries, and in particular to a glue, an electrode plate, a membrane assembly, a battery and a preparation method thereof for a battery. Background Art

[0002] At present, the energy density of liquid lithium-ion batteries is difficult to further increase due to the limited use of positive and negative electrode materials. In addition, the safety of liquid electrolytes has always been the focus of attention in the industry. Therefore, all-solid-state batteries with both high energy density and safety have become a research hotspot in scientific research and industry.

[0003] The main difficulty of existing all-solid-state batteries lies in the solid-solid interface contact problem. Compared with liquid electrolytes, the solid-solid contact between solid electrolytes and electrodes is difficult to maintain a long-term stable interface. The physical and mechanical stability between the electrodes and electrolytes of all-solid-state batteries is also a major challenge. Since the negative electrode undergoes a large volume change during the charge and discharge process, the interface contact position is uneven, which in turn increases the internal resistance of the battery. The positive electrode material also undergoes lattice expansion and contraction during the charge and discharge process, generating internal stress, resulting in a reduction in contact area and increased polarization. These instabilities in mechanical properties will seriously affect the cycle stability of the battery. Summary of the invention

[0004] The purpose of the present application is to provide a glue, an electrode plate, a membrane assembly, a battery and a preparation method thereof for a battery to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] A glue for a battery includes: a first binder, a second binder and a first solvent, wherein the density of the first binder is less than that of the second binder, and the solubility of the first binder in the first solvent is greater than the solubility of the second binder in the first solvent.

[0007] According to an embodiment of the present application, the first binder comprises an alkenyl group;

[0008] And / or, the density of the first binder is 0.5-1.5 g / cm 3 The density of the second binder is 1.6-2.5 g / cm 3 ;

[0009] And / or, the glue solution further includes a catalyst. The introduction of the catalyst promotes the addition reaction between the first binder and the third binder in the electrolyte layer, ensuring that the reaction can be fully carried out.

[0010] According to an embodiment of the present application, the first binder includes at least one of butadiene-acrylonitrile rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene block copolymer, ethylene methyl acrylate, and polystyrene-butadiene copolymer;

[0011] And / or, the second binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene copolymer, and polytetrafluoroethylene-chlorotrifluoroethylene copolymer;

[0012] and / or, the first solvent comprises any one of an ester solvent, a ketone solvent, an aromatic solvent and a saturated alkane solvent, wherein the number of carbon atoms in the first solvent is less than 9;

[0013] Preferably, the ester solvent includes at least one of ethyl acetate and ethyl formate, the ketone solvent includes benzophenone; the aromatic solvent includes any one of xylene, p-xylene and m-xylene, and the saturated alkane solvent includes any one of n-heptane and n-hexane;

[0014] And / or, the catalyst includes at least one of AIBN, ABVN, and BPO.

[0015] According to an embodiment of the present application, the solid content of the glue solution is 1-5wt%;

[0016] And / or, based on the sum of the weights of the first binder and the second binder, the first binder accounts for 1-50wt% and the second binder accounts for 50-99wt%;

[0017] And / or, the catalyst accounts for 0.1-0.5 wt % of the first binder.

[0018] The present application also provides an electrode plate, the material forming the electrode plate includes the aforementioned glue for battery, and the electrode plate includes at least one of a positive electrode plate and a negative electrode plate.

[0019] According to an embodiment of the present application, the material forming the electrode plate further includes an active material, a solid electrolyte, and a conductive agent;

[0020] The solid electrolyte includes at least one of a sulfide electrolyte, an oxide electrolyte and a polymer electrolyte. As an example, the sulfide electrolyte includes but is not limited to Li 6 PS 5 Cl, Li 3 PS 4 , Li 2 SP 2 S 5 ;

[0021] Exemplarily, the conductive agent includes at least one of VGCF, CNTs, and Super P;

[0022] Exemplarily, the active material includes a positive electrode active material or a negative electrode active material;

[0023] Exemplarily, the positive electrode active material includes a ternary positive electrode active material, LiFePO 4 、LiCoO 2 At least one of;

[0024] Exemplarily, the negative electrode active material includes at least one of Si, silicon-carbon composite material, graphite, and lithium titanate;

[0025] Preferably, the mass ratio of the positive electrode active material to the solid electrolyte, the conductive agent, the first binder and the second binder in the glue is (65-90): (5-20): (1-5): (1-5);

[0026] Preferably, the mass ratio of the negative electrode active material to the solid electrolyte, the conductive agent, the first binder and the second binder in the glue is (60-70): (10-20): (5-10): (1-5);

[0027] And / or, the electrode plate is prepared by the following method: active material, solid electrolyte, conductive agent, glue are mixed to prepare electrode slurry, the electrode slurry is coated on the current collector, and the electrode slurry is allowed to stand for 1-3 hours, and then dried at a temperature of 130° C.-180° C. for 1-3 minutes, and then dried at 40-60° C. for 12 hours-24 hours to obtain the electrode plate;

[0028] Preferably, the electrode slurry includes one of a positive electrode slurry and a negative electrode slurry; when a positive electrode active material is used to prepare the electrode slurry, the obtained electrode slurry is a positive electrode slurry, and when a negative electrode active material is used to prepare the electrode slurry, the obtained electrode slurry is a negative electrode slurry;

[0029] The solid content of the positive electrode slurry is 54wt%;

[0030] The solid content of the negative electrode slurry is 47 wt %.

[0031] The present application also provides a membrane assembly, comprising the electrode sheet and the electrolyte layer as described above, wherein the electrode sheet is bonded to the electrolyte layer.

[0032] According to an embodiment of the present application, the raw material for forming the electrolyte layer includes a third binder, and the third binder includes a thiol group;

[0033] Preferably, the third binder comprises at least one of a mixture of a thiol-containing substance and the second binder and a thiol-containing binder;

[0034] The mercapto-containing substance includes at least one of mercapto silicone oil, 3-mercaptopropyl methacrylate, 2-mercaptoethyl acrylate, 4-mercaptobutyl acrylate, γ-mercaptopropyl trimethoxysilane, trimethylolpropane tris(3-mercaptopropionate) type polyurethane, bis(3-mercaptopropionic acid) glycol diacrylate, and JLY-121 polysulfide rubber;

[0035] Preferably, the mercapto-containing substance accounts for 10-20wt% of the mass of the second binder;

[0036] The mercapto group-containing adhesive comprises at least one of a polysulfide rubber adhesive, a mercaptosilane adhesive, a mercapto group-containing acrylate adhesive, and a mercapto group-containing polyurethane adhesive.

[0037] The present application also provides a battery, including the aforementioned glue for battery or the aforementioned electrode plate or the aforementioned membrane combination.

[0038] The present application also provides a method for preparing the battery as described above, the method comprising: assembling the membrane assembly of the battery with a positive electrode sheet or a negative electrode sheet, so that the electrolyte layer is located between the positive electrode sheet and the negative electrode sheet, to obtain a battery;

[0039] Preferably, the electrolyte layer is prepared by: mixing a solid electrolyte, a third binder, and a second solvent to obtain an electrolyte slurry, coating the electrolyte slurry on a substrate, and drying to obtain an electrolyte layer;

[0040] Preferably, the mass ratio of the solid electrolyte to the third binder is (90-99):(1-10);

[0041] and / or, the solid content of the electrolyte slurry is 50-65wt%;

[0042] and / or, the second solvent comprises at least one of toluene, xylene, p-xylene, m-xylene, and butyl butyrate;

[0043] And / or, the drying temperature is 40-60°C, and the drying time is 12-24h;

[0044] And / or, the thickness of the electrolyte layer is 50-80 μm;

[0045] Preferably, after the membrane combination of the battery is assembled with the positive electrode sheet or the negative electrode sheet, the method further comprises: pressing and molding the positive electrode sheet-electrolyte layer-negative electrode sheet structure to obtain a battery; the pressing and molding temperature is 80°C-100°C, the pressing and molding pressure is 500-1000MPa, and the pressing and molding time is 0.5-3h.

[0046] Compared with the prior art, the beneficial effects of this application include:

[0047] The glue of the present application can be used in the positive electrode sheet and the negative electrode sheet of the battery. The glue of the present application includes a first binder and a second binder with different densities and solubilities. The solubility of the first binder in the first solvent is greater than the solubility of the second binder in the first solvent. In the process of preparing the positive electrode sheet and the negative electrode sheet, the second binder with lower solubility and higher density will settle and accumulate on the side close to the current collector. The adhesive with higher density has better adhesion than the binder with lower density, thereby ensuring that the active material layer adheres tightly to the current collector. In the process of preparing the positive electrode sheet and the negative electrode sheet, it is necessary to dry quickly at a higher temperature, and the first binder dissolved in the first solvent will accumulate on the side away from the current collector as the first solvent evaporates. Therefore, the first binder and the second binder are respectively located on opposite sides of the active layer, similar to a "sandwich" shape, which is beneficial to improving the mechanical properties and cycle stability of the electrode.

[0048] The raw materials for preparing the electrode plate of the present application include glue, which can make the first binder and the second binder in the glue be located on opposite sides of the active layer, thereby improving the interface contact between the solid electrolyte and the positive and negative electrodes, and can effectively improve the mechanical properties and cycle stability of the electrode plate.

[0049] The all-solid-state battery of the present application and the all-solid-state battery prepared by the method of the present application can have excellent mechanical properties and cycle stability at the same time due to the above-mentioned electrode plates.

[0050] In some embodiments of the present application, the third binder in the electrolyte layer contains a thiol group, the side of the positive electrode sheet away from the current collector and the side of the negative electrode sheet away from the current collector are in contact with the electrolyte layer, the side of the positive electrode sheet away from the current collector and the side of the negative electrode sheet away from the current collector are enriched with the first binder, and the first binder contains an olefin group. In the process of pressing the positive electrode sheet, the electrolyte layer, and the negative electrode sheet, the olefin group will open the double bond and react with the thiol group to form an anchor at the interface between the positive electrode sheet and the electrolyte layer, and the interface between the negative electrode sheet and the electrolyte layer is anchored, thereby forming a strong binding force at the interface between the positive electrode sheet and the electrolyte layer and the interface between the negative electrode sheet and the electrolyte layer, achieving good performance without external piezoelectric performance, and solving the problem that the original compression molding causes the rebound to easily generate cracks at the two interfaces and requires high-voltage operation to ensure the efficient and smooth transportation of lithium ions. The all-solid-state battery of the present application can be operated without external pressure, breaking through the barriers of the prior art, and opening up a new path for the development of large-size, high-capacity sulfide all-solid-state soft-pack batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0052] Figure 1 This is a photo of the positive electrode sheet in Example 1;

[0053] Figure 2 This is a photo of the negative electrode sheet in Example 1;

[0054] Figure 3 is a photograph of the electrolyte layer in Example 1;

[0055] Figure 4 This is a SEM image of the cross section of the all-solid-state battery in Example 1. DETAILED DESCRIPTION

[0056] As used herein:

[0057] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0058] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0059] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0060] In these examples, parts and percentages are by mass unless otherwise indicated.

[0061] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0062] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0063] In order to better explain the technical solution provided by this application, before the embodiments, the technical solution is first described as a whole, as follows:

[0064] Existing all-solid-state batteries have problems with poor mechanical properties and cycle stability of electrodes.

[0065] In order to improve the above technical problems, the present application provides a glue for batteries, comprising: a first binder, a second binder and a first solvent, wherein the density of the first binder is less than the density of the second binder, and the solubility of the first binder in the first solvent is greater than the solubility of the second binder in the first solvent.

[0066] According to an embodiment of the present application, the first binder comprises an alkenyl group;

[0067] And / or, the density of the first binder is 0.5-1.5 g / cm 3 The density of the second binder is 1.6-2.5 g / cm 3 ;

[0068] According to some embodiments of the present application, the density of the first binder can be 0.5 g / cm 3 , 1g / cm 3 、g / cm 3 , 1.5g / cm 3 Or 0.5-1.5g / cm 3 The density of the second binder can be 1.6 g / cm 3 , 2.0g / cm 3 , 2.5g / cm 3 or 1.6-2.5g / cm 3 Any value in between.

[0069] And / or, the glue solution further includes a catalyst.

[0070] According to an embodiment of the present application, the first binder includes at least one of butadiene-acrylonitrile rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene block copolymer, ethylene methyl acrylate, and polystyrene-butadiene copolymer;

[0071] And / or, the second binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene copolymer, and polytetrafluoroethylene-chlorotrifluoroethylene copolymer;

[0072] And / or, the first solvent includes any one of an ester solvent, a ketone solvent, an aromatic solvent and a saturated alkane solvent, wherein the number of carbon atoms in the first solvent is less than 9; the first binder is completely dissolved in the first solvent, and the second binder is partially dissolved in the first solvent.

[0073] Preferably, the ester solvent includes at least one of ethyl acetate and ethyl formate, the ketone solvent includes benzophenone; the aromatic solvent includes any one of xylene, p-xylene and m-xylene, and the saturated alkane solvent includes any one of n-heptane and n-hexane;

[0074] And / or, the catalyst includes at least one of AIBN, ABVN, and BPO.

[0075] According to an embodiment of the present application, the solid content of the glue solution is 1-5wt%;

[0076] For example, the solid content of the glue solution can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or any value between 1-5wt%;

[0077] And / or, based on the sum of the weights of the first binder and the second binder, the first binder accounts for 1-50wt% and the second binder accounts for 50-99wt%;

[0078] For example, the proportion of the first binder can be 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt% or any value between 1-50wt%, and the proportion of the second binder can be 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 99wt% or any value between 50-99wt%.

[0079] And / or, the catalyst accounts for 0.1-0.5 wt % of the first binder.

[0080] For example, the catalyst accounts for 0.1 wt %, 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.5 wt % or any value between 0.1-0.5 wt % of the first binder.

[0081] The present application also provides an electrode plate, the material forming the electrode plate includes the aforementioned glue for battery, and the electrode plate includes at least one of a positive electrode plate and a negative electrode plate.

[0082] According to an embodiment of the present application, the material forming the electrode plate further includes an active material, a solid electrolyte, and a conductive agent;

[0083] The solid electrolyte includes at least one of a sulfide electrolyte, an oxide electrolyte and a polymer electrolyte, and the sulfide electrolyte includes Li 6 PS 5 Cl, Li 3PS 4 , Li 2 SP 2 S 5 At least one of;

[0084] The conductive agent includes at least one of VGCF, CNTs, and Super P;

[0085] The active material includes a positive electrode active material or a negative electrode active material;

[0086] The positive electrode active material includes a ternary positive electrode active material, LiFePO 4 、LiCoO 2 At least one of; the ternary positive electrode active materials include but are not limited to NCM 811, NCM 523, NCM622.

[0087] The negative electrode active material includes at least one of Si, silicon-carbon composite material, graphite, and lithium titanate; the silicon-carbon composite material includes but is not limited to Si / C450, that is, a silicon-carbon composite material with a theoretical capacity of 450 mAh / g.

[0088] Preferably, the mass ratio of the positive electrode active material to the solid electrolyte, the conductive agent, the first binder and the second binder in the glue is (65-90): (5-20): (1-5): (1-5);

[0089] For example, the mass ratio of the positive electrode active material to the total content of the solid electrolyte, the conductive agent, the first binder and the second binder in the glue solution can be 65:5:1:1, 70:20:5:5, 90:20:5:5 or any value between (65-90):(5-20):(1-5):(1-5).

[0090] Preferably, the mass ratio of the negative electrode active material to the solid electrolyte, the conductive agent, the first binder and the second binder in the glue is (60-70): (10-20): (5-10): (1-5);

[0091] For example, the mass ratio of the negative electrode active material to the total content of the solid electrolyte, the conductive agent, the first binder and the second binder in the glue solution can be 60:10:5:1, 65:15:7.5:3, 68:18:9:5, 70:20:10:5 or any value between (60-70):(10-20):(5-10):(1-5).

[0092] And / or, the electrode plate is prepared by the following method: mixing an active material, a solid electrolyte, a conductive agent, and a glue to prepare an electrode slurry, coating the electrode slurry on a current collector, standing for 1-3 hours, drying at a temperature of 130°C-180°C (for example, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C or any value between 130°C-180°C) for 1-3 minutes (for example, 1 minute, 2 minutes, 3 minutes or any value between 1-3 minutes), and then drying at 40-60°C (for example, 40°C, 50°C, 60°C or any value between 40-60°C) for 12 hours-24 hours (for example, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours, 24 hours or any value between 12 hours and 24 hours) to obtain an electrode plate;

[0093] According to some embodiments of the present application, the current collector includes a positive electrode current collector and a negative electrode current collector. The positive electrode current collector includes but is not limited to aluminum foil, and the negative electrode current collector includes but is not limited to stainless steel foil and carbon-coated copper foil.

[0094] Preferably, the electrode slurry includes one of a positive electrode slurry and a negative electrode slurry;

[0095] The solid content of the positive electrode slurry is 44-64wt%, for example, it can be 44wt%, 45wt%, 50wt%, 54wt%, 55wt%, 60wt%, 64wt% or any value between 44-64wt%;

[0096] The solid content of the negative electrode slurry is 37-57wt%, for example, 37wt%, 40wt%, 47wt%, 50wt%, 57wt% or any value between 37-57wt%.

[0097] The present application also provides a membrane assembly, comprising the electrode sheet and the electrolyte layer as described above, wherein the electrode sheet is bonded to the electrolyte layer.

[0098] All-solid-state batteries are mainly divided into three mainstream technical routes: oxide all-solid-state batteries, polymer all-solid-state batteries, and sulfide all-solid-state batteries. Although various research institutions, universities, and enterprises have their own focuses according to their own business layout, the sulfide system has become the first choice for many researchers due to its excellent ionic conductivity and relatively soft material properties. In China, some companies have successfully developed sulfide all-solid-state soft-pack batteries, but these products are mainly limited to small-size, low-capacity (<2Ah) application scenarios. For large-size, large-capacity (>20Ah) sulfide all-solid-state soft-pack batteries, the market is almost blank. In-depth analysis of the reasons, all-solid-state batteries use a solid-solid contact mechanism. In order to ensure the efficient and smooth transmission of lithium ions during battery operation, it is usually necessary to apply an operating pressure of up to MPa. As the size of the soft pack increases, the required operating pressure also increases, which is difficult to achieve under current technical conditions. Therefore, the operating conditions of the soft pack have become a key factor restricting the large-size preparation of sulfide all-solid-state soft pack batteries.

[0099] In order to improve the problem of harsh operating conditions of all-solid-state soft-pack batteries, in some embodiments of the present application, the raw material for forming the electrolyte layer includes a third binder, and the third binder includes a thiol group;

[0100] Preferably, the third binder comprises at least one of a mixture of a thiol-containing substance and the second binder and a thiol-containing binder;

[0101] The mercapto-containing substance includes at least one of mercapto silicone oil, 3-mercaptopropyl methacrylate, 2-mercaptoethyl acrylate, 4-mercaptobutyl acrylate, γ-mercaptopropyl trimethoxysilane, trimethylolpropane tris(3-mercaptopropionate) type polyurethane, bis(3-mercaptopropionic acid) glycol diacrylate, and JLY-121 polysulfide rubber;

[0102] Preferably, the mercapto-containing substance accounts for 10-20wt% of the mass of the second binder; the mercapto groups in the mercapto-containing substance and the unsaturated bonds in the second binder undergo cross-linking reactions to form a mesh structure, and the formation of an appropriate amount of mesh structure is beneficial to enhancing the mechanical properties of the electrolyte membrane. Excessive mesh structures will seriously affect the ionic conductivity of the electrolyte membrane, and too much mesh structure will cause the electrolyte membrane to become hard and less flexible, affecting the contact with the positive and negative electrode sheets.

[0103] For example, the mercapto-containing substance accounts for 10 wt %, 15 wt %, 20 wt % or any value between 10-20 wt % of the mass of the second binder.

[0104] The mercapto group-containing adhesive comprises at least one of a polysulfide rubber adhesive, a mercaptosilane adhesive, a mercapto group-containing acrylate adhesive, and a mercapto group-containing polyurethane adhesive.

[0105] The present application also provides a battery, which includes the glue solution for battery described above, or includes the electrode tab described above, or includes the membrane combination described above.

[0106] The present application also provides a preparation method of the battery as described above. The preparation method includes: assembling the membrane combination of the battery with the positive electrode tab or the negative electrode tab, so that the electrolyte layer is located between the positive electrode tab and the negative electrode tab to obtain a battery;

[0107] Preferably, the electrolyte layer is prepared by the following method: mixing a solid electrolyte, a third binder, and a second solvent to obtain an electrolyte slurry, coating the electrolyte slurry on a substrate, and drying to obtain the electrolyte layer;

[0108] Preferably, the mass ratio of the solid electrolyte to the third binder is (90 - 99):(1 - 10);

[0109] For example, the mass ratio of the solid electrolyte to the third binder can be 90:10, 95:5, 99:1, or any value between (90 - 99):(1 - 10).

[0110] And / or, the solid content of the electrolyte slurry is 50 - 65 wt%;

[0111] For example, the solid content of the electrolyte slurry can be 50 wt%, 55 wt%, 60 wt%, 65 wt%, or any value between 50 - 65 wt%.

[0112] And / or, the second solvent includes at least one of toluene, xylene, p-xylene, m-xylene, and butyl butyrate;

[0113] And / or, the drying temperature is 40 - 60 °C, and the drying time is 12 - 24 h;

[0114] For example, the drying temperature can be 40 °C, 50 °C, 60 °C, or any value between 40 - 60 °C, and the drying time can be 12 h, 15 h, 18 h, 20 h, 22 h, 24 h, or any value between 12 - 24 h.

[0115] And / or, the thickness of the electrolyte layer is 50 - 80 μm;

[0116] For example, the thickness of the electrolyte layer can be 50 μm, 60 μm, 70 μm, 80 μm, or any value between 50 - 80 μm.

[0117] Preferably, after the membrane assembly of the battery is assembled with the positive electrode or the negative electrode, the method further comprises: pressing and molding the positive electrode-electrolyte layer-negative electrode structure to obtain a battery; the pressing and molding temperature is 80°C-100°C, the pressing and molding pressure is 500-1000MPa, and the pressing and molding time is 0.5-3h. Under this condition, it is conducive to the addition reaction between the first binder and the third binder to be fully carried out. Specifically, under the above pressure conditions, good contact between the positive electrode and the electrolyte layer, and the negative electrode and the electrolyte layer can be guaranteed. At a temperature of 80°C-100°C, an addition reaction can be induced to form an adhesion surface at the two interfaces of the positive electrode and the electrolyte layer, and the negative electrode and the electrolyte layer. In this way, after the pressing and molding is completed, the strong interaction between the binders at the two interfaces can ensure good contact between the two interfaces, and achieve good performance without external piezoelectric performance, thereby solving the problem that the two large interfaces are prone to cracks due to the rebound after pressure relief, and high-pressure operation is required to ensure efficient and smooth transportation of lithium ions.

[0118] For example, the temperature of the press molding may be 80°C, 85°C, 90°C, 95°C, 100°C, or any value between 80°C and 100°C.

[0119] The pressure of the press molding can be 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, 1000MPa or any value between 500-1000MPa, and the time of the press molding can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or any value between 0.5-3h.

[0120] According to some embodiments of the present application, the compression molding of the positive electrode sheet-electrolyte layer-negative electrode sheet structure includes any one of the following situations:

[0121] (1) firstly pressing the electrolyte layer and the positive electrode sheet to obtain a positive electrode sheet-electrolyte layer composite structure, and then pressing the positive electrode sheet-electrolyte layer composite structure with the negative electrode sheet to obtain a battery;

[0122] (2) First, the electrolyte layer and the negative electrode sheet are pressed together to obtain a negative electrode sheet-electrolyte layer composite structure, and then the negative electrode sheet-electrolyte layer composite structure is pressed together with the positive electrode sheet to obtain a battery.

[0123] According to some embodiments of the present application, when the battery is prepared using the above-mentioned situation (1), the temperature for pressing the electrolyte layer and the positive electrode sheet can be 25°C, the pressure for pressing the electrolyte layer and the positive electrode sheet can be 50MPa, and the time for pressing the electrolyte layer and the positive electrode sheet can be 5min.

[0124] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0125] 1. Preparation of all-solid-state batteries

[0126] Example 1

[0127] Embodiment 1 provides an all-solid-state battery, and the preparation method thereof comprises:

[0128] (1) Preparation of glue:

[0129] The first binder styrene-butadiene-styrene block copolymer and the second binder polyvinylidene fluoride were weighed in a mass ratio of 45:55, and then dispersed in xylene by stirring, with a solid content of 5%.

[0130] (2) Preparation of positive electrode sheet:

[0131] According to the mass ratio of the positive electrode active material, sulfide solid electrolyte, conductive agent and the total content of the first binder and the second binder in the glue solution of 70:20:5:5, the solid content is 54wt%, and NCM811, Li 6 PS 5 Cl, CNTs, glue, solvent (xylene), of which NCM811 has a mass of 10g, and the rest are weighed according to the mass ratio, and then mixed on a swing ball mill, and coated on aluminum foil using a SQZ four-sided preparation device in a glove box, and then allowed to stand for 1h and then quickly dried at 130℃ for 2min, and then slowly dried at 60℃ for 12h to obtain a positive electrode sheet, such as Figure 1 shown.

[0132] (3) Preparation of negative electrode sheet:

[0133] According to the mass ratio of the negative electrode active material, the sulfide solid electrolyte, the conductive agent and the total content of the first binder and the second binder in the glue solution of 68:18:9:5, the solid content is 47wt%, and the graphite, Li 6 PS 5 Cl, CNTs, glue and solvent (xylene), of which the mass of graphite is 8g, and the rest are weighed according to the mass ratio, and then mixed on a swing ball mill, and coated on the carbon-coated copper foil using a SQZ four-sided preparation device in a glove box, and then allowed to stand for 1 hour and then quickly dried at 130°C for 2 minutes, and then slowly dried at 60°C for 12 hours to obtain a negative electrode sheet, such as Figure 2 shown.

[0134] (4) Preparation of the electrolyte layer:

[0135] Mix the sulfide electrolyte, the third binder, and butyl butyrate to obtain an electrolyte slurry. Among them, the sulfide electrolyte is Li 6 PS 5 Cl. The third binder includes mercapto silicone oil and polyvinylidene fluoride. Weigh each raw material according to the mass ratio of the sulfide electrolyte to the third binder of 95:5 and the solid content of the electrolyte slurry of 58 wt%. Among them, the mass of Li 6 PS 5 Cl is 9.5 g, the mass of mercapto silicone oil is 0.05 g, and the mass of polyvinylidene fluoride is 0.45 g. The remaining raw materials are weighed according to the mass ratio. Then mix the slurry in a high-speed homogenizer at a speed of 1000 rpm for 30 min. Then use a coating device to coat the electrolyte slurry on the substrate and dry it in an environment of 50 °C for 24 h. The dry thickness of the coating is 80 μm. The photo of the prepared electrolyte layer is as shown in Figure 3 shown.

[0136] (5) Assembly of the soft package:

[0137] Cut the above-mentioned positive electrode sheet and negative electrode sheet into 15 cm * 15 cm, and cut the electrolyte membrane into 15.2 cm * 15.2 cm. Then transfer the electrolyte membrane to the positive electrode sheet through a warm isostatic press and press it under the conditions of 25 °C and 50 MPa for 5 min. Then add the negative electrode sheet to press the positive electrode sheet, the electrolyte layer, and the negative electrode sheet into shape. Specifically, it is pressed into shape through a warm isostatic press. The pressing conditions are 80 °C and 600 MPa for 2 h. Finally, a all-solid-state battery is obtained. The SEM image of the cross-section of the all-solid-state battery is as shown in Figure 4 shown. It can be seen from Figure 4 that the contact between the positive electrode sheet, the negative electrode sheet, and the electrolyte layer is very tight.

[0138] Example 2

[0139] Refer to the method of Example 1 to prepare an all-solid-state battery. Other steps are the same as those in Example 1, except that: the first binder in Example 2 is styrene-isoprene block copolymer.

[0140] Example 3

[0141] Refer to the method of Example 1 to prepare an all-solid-state battery. Other steps are the same as those in Example 1, except that: in the preparation of the electrolyte layer in step (4) of Example 3, the mass of mercapto silicone oil is 0.0833 g, and the mass of polyvinylidene fluoride is 0.417 g.

[0142] Example 4

[0143] The all-solid-state battery was prepared by referring to the method of Example 1. The other steps were the same as those of Example 1, except that: in step (2), the rapid drying temperature of the positive electrode sheet was 140° C. and the time was 1 min. In step (3), the rapid drying temperature of the negative electrode sheet was 140° C. and the time was 1 min.

[0144] Example 5

[0145] An all-solid-state battery was prepared according to the method of Example 1. The other steps were the same as those of Example 1, except that in step (5), the temperature for pressing the positive electrode sheet, the electrolyte layer and the negative electrode sheet was 100°C.

[0146] Comparative Example 1

[0147] An all-solid-state battery is prepared according to the method of Example 1. The other steps are the same as those of Example 1, except that the standing and rapid drying process after coating the positive electrode sheet in step (2) is omitted, and the standing and rapid drying process after coating the negative electrode sheet in step (3) is omitted.

[0148] Comparative Example 2

[0149] An all-solid-state battery was prepared according to the method of Example 1. The other steps were the same as those of Example 1, except that in step (5), the temperature for pressing the positive electrode sheet, the electrolyte layer and the negative electrode sheet was 25°C.

[0150] Comparative Example 3

[0151] Compared with Example 1, other steps are the same as those of Example 1, except that in step (1), only the first binder styrene-butadiene-styrene block copolymer is added.

[0152] Comparative Example 4

[0153] Compared with Example 1, other steps are the same as those of Example 1, except that in step (1), only the second binder polyvinylidene fluoride is added.

[0154] 2. Performance Test

[0155] The performance tests were performed on the all-solid-state batteries prepared in the embodiment and the comparative example respectively.

[0156] At 25°C, a multimeter was used to test the ohmic internal resistance of the all-solid-state battery.

[0157] At 45°C, without external pressure, at 2.5-4.3V, the activation cycle was performed at 0.05C and the cycle was performed at 0.5C.

[0158] The test results of the embodiments and comparative examples are shown in Table 1 and Table 2.

[0159] Table 1 Comparison of ohmic internal resistance of all-solid-state batteries of embodiments and comparative examples

[0160]

[0161]

[0162] By comparing the examples and comparative examples in Table 1, it can be seen that the internal resistance of examples 1-5 is significantly lower than that of comparative examples 1-4. This is because the positive and negative electrode sheets are subjected to a static and rapid drying process after coating, and the temperature during soft package pressing can trigger an addition reaction between the alkenyl functional group and the thiol group to form a strong interaction, so that the interface between the positive electrode sheet and the electrolyte layer, and the interface between the negative electrode sheet and the electrolyte layer has good contact, and finally presents a lower internal resistance.

[0163] Table 2 Comparison of the first efficiency and cycle performance of all-solid-state batteries of the embodiments and comparative examples

[0164] sample First effect 0.05C discharge capacity (Ah) 0.5C cycle 100 cycles retention rate Example 1 86.6％ 1.823 81.2％ Example 2 85.5％ 1.814 82.9％ Example 3 83.7％ 1.800 85.6％ Example 4 87.0％ 1.836 82.4％ Example 5 87.3％ 1.845 83.2％ Comparative Example 1 55.2％ 1.303 20.1％ Comparative Example 2 43.0％ 1.170 13.5％ Comparative Example 3 33.1％ 0.898 10.2％ Comparative Example 4 23.7％ 0.765 9.3％

[0165] By comparing the examples and comparative examples in Table 2, it can be seen that the first effect, 0.05C discharge capacity, and 0.5C cycle retention rate of Examples 1-5 are significantly better than those of Comparative Examples 1-4. This is mainly due to the good contact between the interfaces of the positive electrode sheet and the electrolyte layer, and the negative electrode sheet and the electrolyte layer in the examples, and the rapid and efficient transport of lithium ions can be guaranteed even without external pressure during the electrical performance test, so that the positive and negative electrodes can exert the capacity and first effect of the soft pack design. The cycle performance of Examples 1-5 is significantly better than that of Comparative Examples 1-4, which shows that the soft pack of the examples maintains a more complete battery structure during the cycle, confirming that the positive electrode sheet and the electrolyte layer, as well as the negative electrode sheet and the electrolyte layer, have strong interactions, and even without external pressure, the interfaces of the positive electrode sheet and the electrolyte layer, as well as the negative electrode sheet and the electrolyte layer can be guaranteed to be in good contact during the cycle.

[0166] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0167] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A glue for battery, characterized in that: include: A first binder, a second binder, and a first solvent, wherein the density of the first binder is lower than that of the second binder, and the solubility of the first binder in the first solvent is higher than that of the second binder in the first solvent.

2. The adhesive for battery according to claim 1, characterized in that: The first binder comprises an alkenyl group; And / or, the density of the first binder is 0.5-1.5 g / cm 3 The density of the second binder is 1.6-2.5 g / cm 3 ; And / or, the glue solution also includes a catalyst.

3. The adhesive for battery according to claim 2, characterized in that: The first binder includes at least one of butadiene-acrylonitrile rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene block copolymer, ethylene methyl acrylate, and polystyrene-butadiene copolymer; And / or, the second binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene copolymer, and polytetrafluoroethylene-chlorotrifluoroethylene copolymer; and / or, the first solvent comprises any one of an ester solvent, a ketone solvent, an aromatic solvent and a saturated alkane solvent, wherein the number of carbon atoms in the first solvent is less than 9; Preferably, the ester solvent includes at least one of ethyl acetate and ethyl formate, the ketone solvent includes benzophenone; the aromatic solvent includes any one of xylene, p-xylene and m-xylene, and the saturated alkane solvent includes any one of n-heptane and n-hexane; And / or, the catalyst includes at least one of AIBN, ABVN, and BPO.

4. The adhesive for battery according to claim 2 or 3, characterized in that: The solid content of the glue is 1-5wt%; And / or, based on the sum of the weights of the first binder and the second binder, the first binder accounts for 1-50wt% and the second binder accounts for 50-99wt%; And / or, the catalyst accounts for 0.1-0.5 wt % of the first binder.

5. An electrode plate, characterized in that: The material forming the electrode plate includes the glue for battery according to any one of claims 1 to 4, and the electrode plate includes at least one of a positive electrode plate and a negative electrode plate.

6. The electrode plate according to claim 5, characterized in that: The material forming the electrode plate further includes an active material, a solid electrolyte, and a conductive agent, wherein the active material includes a positive electrode active material or a negative electrode active material; Preferably, the mass ratio of the positive electrode active material to the solid electrolyte, the conductive agent, the first binder and the second binder in the glue is (65-90): (5-20): (1-5): (1-5); Preferably, the mass ratio of the negative electrode active material to the solid electrolyte, the conductive agent, the first binder and the second binder in the glue is (60-70): (10-20): (5-10): (1-5); And / or, the electrode plate is prepared by the following method: mixing active materials, solid electrolytes, conductive agents, and glue to prepare electrode slurry, coating the electrode slurry on a current collector, standing for 1-3 hours, drying at a temperature of 130° C.-180° C. for 1-3 minutes, and then drying at 40-60° C. for 12 hours-24 hours to obtain an electrode plate; Preferably, the electrode slurry includes one of a positive electrode slurry and a negative electrode slurry.

7. A membrane assembly, characterized in that: It comprises the electrode plate and electrolyte layer as described in claim 5 or 6, wherein the electrode plate is bonded to the electrolyte layer.

8. The membrane assembly according to claim 7, characterized in that: The raw material for forming the electrolyte layer includes a third binder, and the third binder includes a mercapto group; Preferably, the third binder comprises at least one of a mixture of a thiol-containing substance and the second binder and a thiol-containing binder; The mercapto-containing substance includes at least one of mercapto silicone oil, 3-mercaptopropyl methacrylate, 2-mercaptoethyl acrylate, 4-mercaptobutyl acrylate, γ-mercaptopropyl trimethoxysilane, trimethylolpropane tris(3-mercaptopropionate) type polyurethane, bis(3-mercaptopropionic acid) glycol diacrylate, and JLY-121 polysulfide rubber; Preferably, the mercapto-containing substance accounts for 10-20wt% of the mass of the second binder; The mercapto group-containing adhesive comprises at least one of a polysulfide rubber adhesive, a mercaptosilane adhesive, a mercapto group-containing acrylate adhesive, and a mercapto group-containing polyurethane adhesive.

9. A battery, characterized in that: The invention comprises the glue for battery as described in any one of claims 1 to 4, or comprises the electrode plate as described in claim 5 or 6, or comprises the membrane combination as described in claim 7 or 8.

10. A method for preparing a battery as claimed in claim 9, characterized in that: The preparation method comprises: assembling the membrane assembly of the battery with a positive electrode sheet or a negative electrode sheet, so that the electrolyte layer is located between the positive electrode sheet and the negative electrode sheet, to obtain a battery; Preferably, the electrolyte layer is prepared by: mixing a solid electrolyte, a third binder, and a second solvent to obtain an electrolyte slurry, coating the electrolyte slurry on a substrate, and drying to obtain an electrolyte layer; Preferably, the mass ratio of the solid electrolyte to the third binder is (90-99):(1-10); and / or, the solid content of the electrolyte slurry is 50-65wt%; and / or, the second solvent comprises at least one of toluene, xylene, p-xylene, m-xylene, and butyl butyrate; And / or, the drying temperature is 40-60°C, and the drying time is 12-24h; And / or, the thickness of the electrolyte layer is 50-80 μm; Preferably, after the membrane combination of the battery is assembled with the positive electrode sheet or the negative electrode sheet, the method further comprises: pressing and molding the positive electrode sheet-electrolyte layer-negative electrode sheet structure to obtain a battery; the pressing and molding temperature is 80°C-100°C, the pressing and molding pressure is 500-1000MPa, and the pressing and molding time is 0.5-3h.

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