Packaging method of all-solid-state battery cell and all-solid-state battery cell packaged thereby

Abstract

This invention provides a method for packaging an all-solid-state battery cell and the resulting all-solid-state battery cell, relating to the field of all-solid-state battery technology. The packaging method includes the following steps: (A) using a rigid, non-adhesive support to wrap or clamp the stacked battery cells, which can slide relative to or reversibly separate from the cell electrode interface under isostatic pressure; (B) performing isostatic pressure treatment after a first vacuum heat seal to densify the interface, wherein the elastic compression σ of the support satisfies σ=(P×d) / (E×1000) and is 20%–50% of the total thickness tolerance of the stacked cells; (C) removing the support during the elastic deformation recovery process of the battery cell, followed by welding the electrode tabs and a second vacuum heat seal. The above packaging method of this invention can effectively alleviate the "wavy edge" problem of existing aluminum-plastic films, while simultaneously achieving uniform pressure distribution and solid-solid interface stabilization, improving the cycle performance and packaging airtightness of the all-solid-state battery cell.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state battery technology, and in particular to a packaging method for an all-solid-state battery cell and the all-solid-state battery cell obtained by packaging. Background Technology

[0002] After the stacking process, all-solid-state pouch cells require isostatic pressing, a crucial step to ensure a tight, low-impedance interface between the solid electrolyte and the electrodes. Since the stacked cells need to remain intact during transfer and casing, temporary fixation is necessary. In existing technologies, adhesive bonding is a common method for fixation.

[0003] However, during isostatic pressing at ultra-high pressures (such as 500 MPa), the adhesive bonding method causes the fixing material to firmly bond with the cell surface, forming a composite stress-bearing body. Due to the differences in compression deformation and modulus of different materials, this bonding hinders the uniform transmission of pressure, leading to localized stress concentration. Macroscopically, this manifests as irreversible plastic wrinkles, or "wavy edges," on the aluminum-plastic film surface at the cell edges or where the fixing material is bonded. This defect not only affects the appearance but may also damage the aluminum-plastic film barrier layer, affecting the consistency of the internal interface of the cell.

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

[0005] The purpose of this invention is to provide a packaging method for all-solid-state battery cells. This packaging method can fundamentally eliminate the "wavy edge" pattern on the surface of the aluminum-plastic film, achieve uniform pressure distribution, and improve the cycle performance of the cell. At the same time, after isostatic pressing, the rigid non-adhesive support is removed during the elastic deformation recovery process of the stacked cell, and a secondary vacuum sealing is performed, which can improve the airtightness of the packaging. In addition, the rigid non-adhesive support of this invention can be removed without damage and can be reused after cleaning, thereby reducing the cost of process materials.

[0006] The second objective of this invention is to provide an all-solid-state battery cell.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The present invention provides a packaging method for an all-solid-state battery cell, comprising the following steps: (A) A rigid non-adhesive support is used to wrap or clamp the laminated battery cell to obtain a fixed laminated battery cell; wherein the interface between the rigid non-adhesive support and the laminated battery cell is a physical interface that allows relative sliding or reversible separation during isostatic pressing. (B) The fixed-layer cells are subjected to vacuum heat sealing and isostatic pressing in sequence; The elastic compressibility σ of the rigid non-cohesive support satisfies the following relationship: σ = (P × d) / (E × 1000), and the value of σ is 20% to 50% of the total thickness tolerance of the laminated cells; In the formula, σ is the elastic compression of the support in the pressure direction, in mm; d represents the thickness of the rigid, non-adhesive support, in mm; E is the elastic modulus, in GPa; P represents the isostatic pressure after isostatic pressing, in MPa. (C) After isostatic pressing, during the elastic deformation recovery process of the laminated cell, the rigid non-adhesive support is removed, and then the tabs are welded and vacuum heat-sealed a second time.

[0008] Furthermore, the rigid non-adhesive support is selected from one of polyethylene terephthalate (PET) film, polypropylene (PP) film, polyphenylene sulfide (PPS) film, and polyimide (PI) film.

[0009] Furthermore, the elastic modulus E of the rigid non-cohesive support and its thickness d satisfy the following: E×d=5×10 5 N / m ~ 2×10 6 N / m.

[0010] Furthermore, the thickness d of the rigid non-adhesive support is 0.05mm~1.0mm, preferably 0.1mm~0.5mm.

[0011] Furthermore, the (C) laminated cell being in the process of elastic deformation recovery refers to the period within 3 to 15 minutes after the laminated cell is removed following isostatic pressing.

[0012] Furthermore, the vacuum heat sealing in (B) includes: first vacuum drying, and then hot pressing sealing; Preferably, the vacuum drying temperature for the first vacuum heat sealing is 50~80℃, the time is 12~48 h, and the vacuum degree is -0.09~-0.1MPa; Preferably, the hot-press sealing pressure of the single vacuum heat sealing is 0.2~0.5MPa, and the time is 1~10s.

[0013] Furthermore, the vacuum drying temperature for the first vacuum heat sealing is 60°C, the vacuum drying time is 24 h, and the vacuum degree is -0.095 MPa. The heat sealing pressure for the first vacuum heat sealing is 0.3 MPa, and the heat sealing time is 1~10 s.

[0014] Furthermore, the isostatic pressing method (B) includes: applying a pressure of 200 to 800 MPa to the battery cell after primary encapsulation, holding the pressure for 10 to 30 minutes, and then releasing the pressure to complete the isostatic pressing process.

[0015] Furthermore, the secondary vacuum heat sealing in (C) includes: vacuum drying followed by heat sealing; Preferably, the vacuum drying temperature of the secondary vacuum heat sealing is 50~80℃, the time is 12~48 h, and the vacuum degree is -0.09~-0.1MPa; Preferably, the hot-press sealing pressure of the secondary vacuum heat sealing is 0.2~0.5MPa, and the time is 1~10s; The present invention provides an all-solid-state battery cell, which is mainly obtained by the above-mentioned packaging method.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a packaging method for an all-solid-state battery cell. The packaging method can fundamentally eliminate the "wavy edge" pattern on the surface of the aluminum-plastic film, achieve uniform pressure distribution, and improve the cycle performance of the cell. At the same time, after isostatic pressing, the rigid non-adhesive support is removed and a secondary vacuum seal is performed during the elastic deformation recovery process of the stacked cell, which can improve the airtightness of the seal. In addition, the rigid non-adhesive support of this invention can be removed without damage and can be reused after cleaning, thereby reducing the cost of process materials.

[0017] The all-solid-state battery cell provided by this invention is prepared by the above-described encapsulation method of this invention. Due to the advantages of the encapsulation method of this invention, the all-solid-state battery cell has an aluminum-plastic film surface without "wavy edge" defects, a uniform and dense solid-solid interface, good encapsulation hermeticity, and excellent cycle performance. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the soft-pack battery cell after isostatic pressing in Example 1 of the present invention, provided in Experimental Example 1 of the present invention; Figure 2 This is a schematic diagram of the soft-pack battery cell after isostatic pressing, which is provided in Comparative Example 1 of Experimental Example 1 of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] According to one aspect of the present invention, a method for packaging an all-solid-state battery cell includes the following steps: (A) A rigid non-adhesive support is used to wrap or clamp the laminated battery cell to obtain a fixed laminated battery cell; wherein the interface between the rigid non-adhesive support and the laminated battery cell is a physical interface that allows relative sliding or reversible separation during isostatic pressing. (B) The fixed-layer cells are subjected to vacuum heat sealing and isostatic pressing in sequence; The elastic compressibility σ of the rigid non-cohesive support satisfies the following relationship: σ = (P × d) / (E × 1000), and the value of σ is 20% to 50% of the total thickness tolerance of the laminated cells; In the formula, σ is the elastic compression of the support in the pressure direction, in mm; d represents the thickness of the rigid, non-adhesive support, in mm; E is the elastic modulus, in GPa; P represents the isostatic pressure after isostatic pressing, in MPa. (C) After isostatic pressing, during the elastic deformation recovery process of the laminated cell, the rigid non-adhesive support is removed, and then the tabs are welded and vacuum heat-sealed a second time.

[0022] This invention provides a packaging method for an all-solid-state battery cell. The packaging method can fundamentally eliminate the "wavy edge" pattern on the surface of the aluminum-plastic film, achieve uniform pressure distribution, and improve the cycle performance of the cell. At the same time, after isostatic pressing, the rigid non-adhesive support is removed and a secondary vacuum seal is performed during the elastic deformation recovery process of the stacked cell, which can improve the airtightness of the seal. In addition, the rigid non-adhesive support of this invention can be removed without damage and can be reused after cleaning, thereby reducing the cost of process materials.

[0023] It should be noted that the "total thickness tolerance of the laminated cells" mentioned above refers to the difference between the maximum and minimum thickness allowed by the design specifications (i.e., the total tolerance, for example, ±0.05 mm corresponds to a total tolerance of 0.1 mm). The elastic compression σ of the support body needs to fall within 20% to 50% of this tolerance value to effectively compensate for thickness fluctuations and achieve uniform pressure distribution.

[0024] The key mechanism of this invention lies in the fact that during isostatic pressing, the aluminum-plastic film adheres tightly to the outer surface of a rigid, non-adhesive support under pressure. Because the support itself has high flatness, and its elastic compression σ is configured to compensate for the microscopic unevenness of the laminated cell surface, the aluminum-plastic film actually contacts a macroscopically flat, rigid surface, rather than the uneven surface of the cell electrodes. This ensures that the aluminum-plastic film is subjected to uniform stress across its entire area, and no plastic wrinkles or "wavy edges" are generated after pressure is released.

[0025] Specifically, the effects of the technical solution of this invention can be summarized as follows: 1. This invention uses a rigid, non-adhesive support and a physical interface that allows relative sliding or reversible separation to eliminate the "wavy edge" defect on the surface of the aluminum-plastic film. 2. The support body of the present invention serves as a pressure equalization element, compensating for the thickness tolerance of the laminate, and ensuring that the isostatic pressure is uniformly transmitted in each layer of the cell, which is beneficial to improving cycle performance. 3. In this invention, after isostatic pressing, the support is removed and a secondary vacuum seal is performed during the elastic deformation recovery process of the battery cell. The negative pressure adsorption effect generated by the rebound is used to eliminate the micro gaps at the sealing interface in advance, which is beneficial to improving airtightness and long-term cycle retention. 4. The support can be removed without damage due to its non-adhesive design and can be reused after cleaning, thereby reducing the cost of process consumables.

[0026] Furthermore, during the isostatic pressing process of this invention, the elastic compression σ of the rigid non-adhesive support in the pressure direction satisfies the following relationship: σ = (P × d) / (E × 1000). This formula characterizes the support's ability to compensate for microscopic unevenness on the surface of the stacked cells. By configuring the parameters E, d, and P, σ is kept within 20% to 50% of the total thickness tolerance of the stacked cells to achieve uniform pressure distribution and interface stabilization. Experimental verification shows that when this parameter configuration relationship is not met, the support cannot effectively compensate for the thickness tolerance of the stacked cells, resulting in uneven transmission of isostatic pressure across the cell layers, which in turn causes "wavy edge" defects on the aluminum-plastic film surface.

[0027] Meanwhile, it should be noted that the present invention uses a removable rigid non-adhesive support to wrap or clamp the battery cell; the rigid non-adhesive support is not bonded to the surface of the battery cell electrode sheet by adhesive, and the interface between the two is designed as a sliding / separable physical interface; the support also serves as an isostatic pressure distribution control element, using its own high rigidity and flatness to apply physical constraints to the battery cell, compensating for the microscopic unevenness of the stacked surface caused by the accumulation of thickness tolerances of the positive and negative electrode sheets and electrolyte membrane, so that the isostatic pressure can be evenly transmitted to each unit layer of the battery cell through the support, thereby effectively avoiding pressure concentration in local protrusions.

[0028] In a preferred embodiment of the present invention, the rigid non-adhesive support is selected from one of polyethylene terephthalate (PET) film, polypropylene (PP) film, polyphenylene sulfide (PPS) film, and polyimide (PI) film.

[0029] In a preferred embodiment, the present invention uses polyethylene terephthalate (PET) film, polypropylene (PP) film, polyphenylene sulfide (PPS) film, and polyimide (PI) film as rigid non-adhesive supports, which can reliably fix the stacked battery cells and maintain a physical interface that allows relative sliding or reversible separation between the support and the battery cell electrodes during isostatic pressing. This helps to eliminate the "wavy edge" defect on the surface of the aluminum-plastic film, promote uniform pressure distribution, improve the airtightness of the packaging, and enhance the reusability of the support.

[0030] In a preferred embodiment of the present invention, the elastic modulus E of the rigid non-adhesive support and its thickness d satisfy: E×d=5×10 5 N / m ~ 2×10 6 N / m.

[0031] In a preferred embodiment of the present invention, the thickness d of the rigid non-adhesive support is 0.05 mm to 1.0 mm, for example, it can be 0.05 mm, 0.1 mm, 0.25 mm, 0.5 mm, 1.0 mm, or any value between 0.05 mm and 1.0 mm; preferably 0.1 mm to 0.5 mm.

[0032] In a preferred embodiment of the present invention, (B) the laminated cell is in the process of elastic deformation recovery, which means within 3 to 15 minutes after the laminated cell is removed after isostatic pressing.

[0033] In a preferred embodiment, the present invention defines the elastic deformation recovery process of the stacked cell as within 3 to 15 minutes after the stacked cell is removed after isostatic pressing. This is beneficial to generate an instantaneous negative pressure adsorption effect when the cell undergoes dimensional recovery, thereby eliminating micro gaps at the packaging interface in advance, improving the airtightness of the secondary vacuum packaging and the cell's long-term cycle retention capability.

[0034] It should be noted that "elastic deformation recovery" refers to the stage after the cell has undergone isostatic pressure release, during which the dimensional shrinkage process of the internal layers of material due to compression deformation has not yet fully completed (usually 3-15 minutes after removal, depending on the cell size, material, and isostatic pressure). Removing the cell at this stage allows the negative pressure generated by the rebound to assist in subsequent encapsulation. Under pressures of 200-800 MPa, the distance between the support and the electrode surface is compressed to the atomic scale. The instantaneously enhanced van der Waals force is sufficient to ensure the relative position is fixed. After pressure is released and the cell is removed, this force disappears as the distance recovers, achieving non-destructive removal.

[0035] In a preferred embodiment of the present invention, the vacuum heat sealing in step (B) includes: vacuum drying followed by heat sealing; Preferably, the vacuum drying temperature for the first vacuum heat sealing is 50~80℃, the time is 12~48 h, and the vacuum degree is -0.09~-0.1MPa; Preferably, the hot-press sealing pressure of the single vacuum heat sealing is 0.2~0.5MPa, and the time is 1~10s.

[0036] More preferably, the vacuum drying temperature of the first vacuum heat sealing is 60°C, the vacuum drying time is 24 h, and the vacuum degree is -0.095 MPa; More preferably, the hot-pressing sealing pressure of the first vacuum heat sealing is 0.3 MPa, and the hot-pressing sealing time is 8 s.

[0037] In a preferred embodiment of the present invention, the isostatic pressing method (B) includes: applying a pressure of 200 to 800 MPa to the battery cell after primary encapsulation, holding the pressure for 10 to 30 minutes, and then releasing the pressure to complete the isostatic pressing process.

[0038] In a preferred embodiment of the present invention, the secondary vacuum heat sealing in (C) includes: vacuum drying first, followed by heat sealing; Preferably, the parameters of the secondary vacuum heat seal are the same as those of the primary vacuum heat seal; The vacuum drying temperature for the secondary vacuum heat sealing is 50~80℃, the time is 12~48 h, the vacuum degree is -0.09~-0.1MPa, and the hot-press sealing pressure for the secondary vacuum heat sealing is 0.2~0.5MPa, and the time is 1~10s. Preferably, in the packaging process of the all-solid-state battery cell of the present invention, the positive electrode material includes a ternary material positive electrode or a lithium iron phosphate positive electrode; the negative electrode material includes silicon-carbon, silicon, or compounds thereof; the binder is selected from styrene-butadiene-styrene triblock copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), polyvinyl acetate (PVAC), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), and polyvinyl alcohol (PVA) or any combination thereof; the electrolyte is selected from Li6PS5X (X=Cl,Br,I), Li 10 MP2S 12 (M = Si, Ge, Sn), Li3PS4, or any combination thereof.

[0039] According to one aspect of the present invention, an all-solid-state battery cell is mainly obtained by the above-described encapsulation method.

[0040] The all-solid-state battery cell provided by this invention is prepared by the above-described encapsulation method of this invention. Due to the advantages of the encapsulation method of this invention, the all-solid-state battery cell has an aluminum-plastic film surface without "wavy edge" defects, a uniform and dense solid-solid interface, good encapsulation hermeticity, and excellent cycle performance.

[0041] The technical solution of the present invention will be further described below with reference to the embodiments.

[0042] Example 1 A method for packaging an all-solid-state battery cell, the packaging method comprising: (I) Preparation of electrode sheets and electrolyte layer: Preparation of the positive electrode: Weigh 80 wt.% LiNi 0.8 Co 0.1 Mn 0.1 O2 cathode material, 15 wt.% solid electrolyte, 2 wt.% VGCF conductive agent and 3 wt.% SEBS binder are added to a suitable butyl butyrate solvent, and then the components are evenly dispersed using a high-speed disperser to form a stable slurry, which is then evenly coated on an aluminum foil current collector. After baking, rolling, slitting and die-cutting processes, the cathode sheet is obtained. Preparation of electrolyte membrane: Weigh 98 wt.% LPSCl electrolyte material and 2 wt.% SEBS binder, add them to a suitable xylene solvent, and then use a high-speed disperser to uniformly disperse each component to form a stable slurry, which is then uniformly coated on an aluminum foil current collector and baked to obtain the electrolyte membrane. Preparation of negative electrode sheet: Weigh 62 wt.% silicon-carbon negative electrode material, 30 wt.% solid electrolyte, 4 wt.% VGCF conductive agent and 4 wt.% HNBR binder, add them to a suitable xylene solvent, and then use a high-speed disperser to uniformly disperse each component to form a stable slurry, which is then uniformly coated on a copper foil current collector and baked to obtain the negative electrode sheet; Negative electrode transfer process: The prepared negative electrode and electrolyte are rolled and transferred at 10MPa, and then die-cut to obtain the transferred negative electrode sheet.

[0043] (II) Fixing the stacked pieces to the support: In a dry room (dew point < -40℃), 13 units are stacked in the order of "positive electrode - negative electrode" to form a stacked cell with a size of 100 mm (L) × 80 mm (width) × 2.6 mm (initial stacking thickness) and a total thickness tolerance of ±0.05 mm (i.e., a total tolerance of 0.1 mm). Two flat PET films with a thickness of 0.25 mm are used as rigid, non-adhesive supports with an elastic modulus E = 3.5 GPa. The stacked battery cell is sandwiched between the two PET films to form a rigid sandwich structure for fixation, ensuring that there is no adhesive, coating, or any sticky substance in contact between the support and the surface of the battery cell, and that the interface is purely physical contact. (III) Primary Encapsulation and Isostatic Pressing: The fixed battery cell was placed into an aluminum-plastic film bag and vacuum-baked at 60°C for 24 hours before the first heat sealing. The vacuum degree of the first vacuum heat sealing was -0.095MPa, the heat sealing pressure of the first vacuum heat sealing was 0.3MPa, and the heat sealing time was 8s.

[0044] After initial encapsulation, the battery cells undergo cold isostatic pressing at 500 MPa for 10 minutes.

[0045] Under isostatic pressing conditions, the elastic compression σ of a rigid, non-cohesive support in the pressure direction satisfies the following relationship: σ = (P × d) / (E × 1000), where: σ: The equivalent elastic compression of the support in the direction of pressure, in mm; P: Isostatic pressure, unit MPa; E: Elastic modulus of the support, in GPa; d: Support thickness, in mm.

[0046] Substituting P = 500MPa, E = 3.5GPa, and d = 0.25mm, we get σ = 0.0357mm.

[0047] Meanwhile, in this embodiment, the compression amount is controlled at 35.7% of the total thickness tolerance of the cell stack, achieving a good balance between constraint and buffer.

[0048] (iv) Removal of support and secondary encapsulation: After the isostatic pressure equipment is depressurized, the cell is taken out of the hatch within 5 minutes (at which time the cell is still in an elastic rebound state), the aluminum-plastic film is removed, the PET support is completely removed, and the cell is observed to have a slight dimensional recovery after the support is removed. Then the tabs are welded and the final secondary vacuum encapsulation is performed to obtain the all-solid-state battery cell.

[0049] The secondary vacuum sealing includes: after vacuum baking at 60°C for 24 hours, a second heat sealing is performed. The vacuum degree of the secondary vacuum heat sealing is -0.095MPa, the heat sealing pressure of the secondary vacuum heat sealing is 0.3MPa, and the heat sealing time is 8s.

[0050] Example 2 This embodiment is identical to Example 1 except that the rigid non-adhesive support in Example 1 is replaced with a 0.25mm thick polypropylene (PP) film (E=1.5 GPa, calculated σ=0.05mm). Specifically, it is as follows: A method for encapsulating an all-solid-state battery cell, the encapsulation method comprising: (I) Preparation of electrode sheets and electrolyte layer: Preparation of the positive electrode sheet: Same as in Example 1; Preparation of electrolyte membrane: Same as in Example 1; Preparation of the negative electrode sheet: Same as in Example 1; Negative electrode transfer process: Same as in Example 1.

[0051] (II) Fixing the stacked pieces to the support: In a dry room (dew point < -40℃), 13 units are stacked in the order of "positive electrode - negative electrode" to form a stacked cell with a size of 100 mm (L) × 80 mm (width) × 2.6 mm (initial stacking thickness) and a total thickness tolerance of ±0.05 mm (i.e., a total tolerance of 0.1 mm). Two 0.25mm thick polypropylene (PP) films are used as rigid non-adhesive supports with an elastic modulus E=1.5 GPa. The stacked battery cells are sandwiched between the two PP films to form a rigid sandwich structure for fixation, ensuring that there is no adhesive, coating or any sticky substance in contact between the support and the surface of the battery cells, and the interface is purely physical contact. (III) Primary Encapsulation and Isostatic Pressing: The fixed battery cell is placed into an aluminum-plastic film bag and vacuum-baked at 60°C for 24 hours before the first heat sealing. The sealed battery cell is then subjected to cold isostatic pressing at 500 MPa for 10 minutes.

[0052] Under isostatic pressing conditions, the elastic compression σ of a rigid, non-cohesive support in the pressure direction satisfies the following relationship: σ = (P × d) / (E × 1000), where: σ: The equivalent elastic compression of the support in the direction of pressure, in mm; P: Isostatic pressure, unit MPa; E: Elastic modulus of the support, in GPa; d: Support thickness, in mm.

[0053] Substituting P = 500MPa, E = 1.5GPa, and d = 0.25mm, we get σ = 0.05mm.

[0054] Meanwhile, in this embodiment, the compression amount is controlled within 50% of the total thickness tolerance of the cell stack, falling within the 20%~50% boundary. After isostatic pressing, the appearance is flat and the performance is relatively good.

[0055] (iv) Same as Example 1.

[0056] Example 3 In this embodiment, the rigid non-adhesive support in Example 1 is replaced with a 0.15mm thick polyphenylene sulfide (PPS) film (E=4.0 GPa, calculated σ=0.0188mm), except that the rest is the same as in Example 1, as detailed below: A method for packaging an all-solid-state battery cell, the packaging method comprising: (I) Preparation of electrode sheets and electrolyte layer: Preparation of the positive electrode sheet: Same as in Example 1; Preparation of electrolyte membrane: Same as in Example 1; Preparation of the negative electrode sheet: Same as in Example 1; Negative electrode transfer process: Same as in Example 1.

[0057] (II) Fixing the stacked pieces to the support: In a dry room (dew point < -40℃), 13 units are stacked in the order of "positive electrode - negative electrode" to form a stacked cell with a size of 100 mm (L) × 80 mm (width) × 2.6 mm (initial stacking thickness) and a total thickness tolerance of ±0.05 mm (i.e., a total tolerance of 0.1 mm). Two 0.15mm thick polyphenylene sulfide (PPS) films are used as rigid non-adhesive supports with an elastic modulus E=4.0GPa. The stacked battery cells are sandwiched between the two PPS films to form a rigid sandwich structure for fixation, ensuring that there is no adhesive, coating or any sticky substance in contact between the support and the surface of the battery cells, and the interface is purely physical contact. (III) Primary Encapsulation and Isostatic Pressing: The fixed battery cell is placed into an aluminum-plastic film bag and vacuum-baked at 60°C for 24 hours before the first heat sealing. The sealed battery cell is then subjected to cold isostatic pressing at 500 MPa for 10 minutes.

[0058] Under isostatic pressing conditions, the elastic compression σ of a rigid, non-cohesive support in the pressure direction satisfies the following relationship: σ = (P × d) / (E × 1000), where: σ: The equivalent elastic compression of the support in the direction of pressure, in mm; P: Isostatic pressure, unit MPa; E: Elastic modulus of the support, in GPa; d: Support thickness, in mm.

[0059] Substituting P = 500MPa, E = 4.0GPa, and d = 0.15mm, we get σ = 0.0188mm.

[0060] Meanwhile, in this embodiment, the compression amount is controlled at 18.8% of the total thickness tolerance of the cell stack, slightly lower than the 20% lower limit. Experiments showed slight unevenness in appearance, but this was better than the adhesive fixing method (Comparative Example 1), indicating that this percentage should not be too low.

[0061] (iv) Same as Example 1.

[0062] Comparative Example 1 In this embodiment, the rigid non-adhesive support in Example 1 is replaced with commercially available 3M 5419 polyimide tape (total thickness 0.07mm, substrate elastic modulus approximately 3.0GPa), cut into 4 sections and pasted onto both sides of the stacked battery cell for fixation. Otherwise, the embodiments are the same as in Example 1.

[0063] According to the formula, σ = 0.0117 mm, which is only 11.7% of the total thickness tolerance of the laminated cell, far below the 20%~50% range required by this invention. Moreover, the tape and the cell surface are bonded together, and cracks occur at the interface due to uneven stress during the isostatic pressing process.

[0064] Comparative Example 2 In this embodiment, the rigid non-adhesive support in Example 1 is replaced with a layer of commercially available teas4848PV1 surface protective tape (the substrate is a polyethylene (PE) protective film with a thickness of 0.048 mm, an elastic modulus of approximately 0.5 GPa, and an acrylic adhesive with weak adhesion). Otherwise, it is the same as in Example 1.

[0065] Calculations showed that σ = 0.048 mm, which accounts for 48% of the total thickness tolerance of the laminated cell. Although this meets the requirements, the weakly tacky acrylic adhesive layer still adheres to the cell surface during the 500 MPa isostatic pressing process, resulting in partial cracking of the electrode sheet and making it impossible to conduct subsequent experiments.

[0066] Comparative Example 3 The division step (four) of this comparative example is as follows: “(iv) Removal of support and secondary packaging: After the isostatic pressure equipment is depressurized, the cell is taken out after the door is opened. The aluminum-plastic film is removed 20 minutes later, and the PET support is completely removed. The cell is observed to have a slight dimensional recovery after the support is removed. Then the tabs are welded and the final secondary vacuum packaging is performed to obtain the all-solid-state battery cell.” Except for the above, the rest is the same as in Example 1.

[0067] Comparative Example 4 The division step (four) of this comparative example is as follows: “(iv) Removal of support and secondary encapsulation: After the isostatic pressure equipment is depressurized, the aluminum-plastic film is removed 1 minute after the cell is taken out (at this time, the elastic rebound of the cell is not sufficient). The PET support is completely removed. The cell is observed to have a slight dimensional recovery after the support is removed. Then the tabs are welded and the final secondary vacuum encapsulation is performed to obtain the all-solid-state battery cell.” Except for the above, the rest is the same as in Example 1.

[0068] Comparative Example 5 A method for packaging an all-solid-state battery cell, the packaging method comprising: (I) Preparation of electrode sheets and electrolyte layer: Preparation of the positive electrode sheet: Same as in Example 1; Preparation of electrolyte membrane: Same as in Example 1; Preparation of the negative electrode sheet: Same as in Example 1; Negative electrode transfer process: Same as in Example 1.

[0069] (II) Fixing the stacked pieces to the support: In a dry room (dew point < -40℃), 13 units are stacked in the order of "positive electrode - negative electrode" to form a stacked cell with a size of 100 mm (L) × 80 mm (width) × 2.6 mm (initial stacking thickness) and a total thickness tolerance of ±0.05 mm (i.e., a total tolerance of 0.1 mm). Two flat PET films with a thickness of 0.1 mm are used as rigid, non-adhesive supports with an elastic modulus E = 3.5 GPa. The stacked battery cell is sandwiched between the two PET films to form a rigid sandwich structure for fixation, ensuring that there is no adhesive, coating, or any sticky substance in contact between the support and the surface of the battery cell, and that the interface is purely physical contact. (III) Primary Encapsulation and Isostatic Pressing: The fixed battery cell is placed into an aluminum-plastic film bag and vacuum-baked at 60°C for 24 hours before the first heat sealing. The sealed battery cell is then subjected to cold isostatic pressing at 500 MPa for 10 minutes.

[0070] Under isostatic pressing conditions, the elastic compression σ of a rigid, non-cohesive support in the pressure direction satisfies the following relationship: σ = (P × d) / (E × 1000), where: σ: The equivalent elastic compression of the support in the direction of pressure, in mm; P: Isostatic pressure, unit MPa; E: Elastic modulus of the support, in GPa; d: Support thickness, in mm.

[0071] Substituting P = 500MPa, E = 3.5GPa, and d = 0.1mm, we get σ = 0.0143mm.

[0072] Meanwhile, in this comparative example, the compression amount was controlled at 14.3% of the total thickness tolerance of the cell stack (less than 20%), resulting in partial cracking of the electrode sheet, making it impossible to conduct subsequent experiments.

[0073] Comparative Example 6 A method for packaging an all-solid-state battery cell, the packaging method comprising: (I) Preparation of electrode sheets and electrolyte layer: Preparation of the positive electrode sheet: Same as in Example 1; Preparation of electrolyte membrane: Same as in Example 1; Preparation of the negative electrode sheet: Same as in Example 1; Negative electrode transfer process: Same as in Example 1.

[0074] (II) Fixing the stacked pieces to the support: In a dry room (dew point < -40℃), 13 units are stacked in the order of "positive electrode - negative electrode" to form a stacked cell with a size of 100 mm (L) × 80 mm (width) × 2.6 mm (initial stacking thickness) and a total thickness tolerance of ±0.05 mm (i.e., a total tolerance of 0.1 mm). Two flat PET films with a thickness of 0.5 mm are used as rigid, non-adhesive supports with an elastic modulus E = 3.5 GPa. The stacked battery cell is sandwiched between the two PET films to form a rigid sandwich structure for fixation, ensuring that there is no adhesive, coating, or any sticky substance in contact between the support and the surface of the battery cell, and the interface is purely physical contact. (III) Primary Encapsulation and Isostatic Pressing: The fixed battery cell is placed into an aluminum-plastic film bag and vacuum-baked at 60°C for 24 hours before the first heat sealing. The sealed battery cell is then subjected to cold isostatic pressing at 500 MPa for 10 minutes.

[0075] Under isostatic pressing conditions, the elastic compression σ of a rigid, non-cohesive support in the pressure direction satisfies the following relationship: σ = (P × d) / (E × 1000), where: σ: The equivalent elastic compression of the support in the direction of pressure, in mm; P: Isostatic pressure, unit MPa; E: Elastic modulus of the support, in GPa; d: Support thickness, in mm.

[0076] Substituting P = 500MPa, E = 3.5GPa, and d = 0.5mm, we get σ = 0.0714mm.

[0077] Meanwhile, in this comparative example, the compression amount was controlled at 71.4% (greater than 50%) of the total thickness tolerance of the cell stack, and cracking of the electrode sheets was found. Subsequent testing was not possible.

[0078] Experimental Example 1 This experimental example is based on the battery cell samples prepared in Examples 1-3 and Comparative Examples 1-6 of the present invention. Systematic performance tests were conducted under unified conditions to objectively verify the technical effects of the present invention in eliminating "wavy edge" defects, improving interface consistency and long-term cycle reliability.

[0079] The specific testing methods are as follows: In an environment of 35℃, the soft-pack batteries were first formed at 0.1C using a Blue Electricity Tester, and then the cycle performance of each assembled all-solid-state soft-pack battery was tested at 0.5C and 1000 cycles. The energy density E (Wh / kg) was calculated by E=(C×V) / m, where C is the measured discharge capacity (Ah), V is the average voltage during discharge (V), and m is the mass of the finished battery (kg).

[0080] Please refer to the table below for specific test results.

[0081] Table 1:

[0082] Figure 1 A schematic diagram of the soft-pack battery cell after isostatic pressing in Example 1 provided for this experimental case.

[0083] Figure 2 This is a schematic diagram of the soft-pack battery cell after isostatic pressing, which is provided for Comparative Example 1 in this experiment.

[0084] As can be seen from Examples 1-3 and Comparative Examples 1, 5, and 6 in Table 1: when the σ value is within the range of 20% to 50% of the total thickness tolerance of the laminated cell, the old aluminum-plastic film is flat and wrinkle-free, the internal interface of the cell is dense, and the cycle performance is excellent; when the σ value is less than 20% (Comparative Examples 1 and 5), the old film has wavy edges or the electrode cracks; when the σ value is greater than 50% (Comparative Example 6), the electrode cracks.

[0085] In Comparative Example 3 (removal of the support too late, 20 min), although the old film was smooth and the interface was dense, the airtightness was poor and the cycle performance decreased after secondary encapsulation because the cell elastic recovery window was missed. In Comparative Example 4 (removal too early, 1 min), microcracks appeared at the interface because the cell structure was not stable.

[0086] Comparative Example 2 used a weakly tacky tape. Although the σ value was within the range, the stickiness caused the electrode to crack, indicating that non-stickiness is a necessary condition.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 invention.

Claims

1. A method for packaging an all-solid-state battery cell, characterized in that, Includes the following steps: (A) A rigid non-adhesive support is used to wrap or clamp the laminated battery cell to obtain a fixed laminated battery cell; wherein the interface between the rigid non-adhesive support and the laminated battery cell is a physical interface that allows relative sliding or reversible separation during isostatic pressing. (B) The fixed-layer cells are subjected to vacuum heat sealing and isostatic pressing in sequence; The elastic compressibility σ of the rigid non-cohesive support satisfies the following relationship: σ = (P × d) / (E × 1000), and the value of σ is 20% to 50% of the total thickness tolerance of the laminated cells; In the formula, σ is the elastic compression of the support in the pressure direction, in mm; d represents the thickness of the rigid, non-adhesive support, in mm; E is the elastic modulus, in GPa; P represents the isostatic pressure after isostatic pressing, in MPa. (C) After isostatic pressing, during the elastic deformation recovery process of the laminated cell, the rigid non-adhesive support is removed, and then the tabs are welded and vacuum heat-sealed a second time.

2. The packaging method for an all-solid-state battery cell according to claim 1, characterized in that, The rigid non-adhesive support is selected from one of polyethylene terephthalate (PET) film, polypropylene (PP) film, polyphenylene sulfide (PPS) film, and polyimide (PI) film.

3. The packaging method for an all-solid-state battery cell according to claim 2, characterized in that, The elastic modulus E of the rigid non-cohesive support and its thickness d satisfy the following: E×d=5×10 5 N / m ~ 2×10 6 N / m。 4. The packaging method for an all-solid-state battery cell according to claim 1, characterized in that, The thickness d of the rigid non-adhesive support is 0.05mm-1.0mm, preferably 0.1mm-0.5mm.

5. The packaging method for an all-solid-state battery cell according to claim 1, characterized in that, The term (C) "in the process of elastic deformation recovery of the laminated cell" refers to the period within 3 to 15 minutes after the laminated cell is removed following isostatic pressing.

6. The packaging method for an all-solid-state battery cell according to claim 1, characterized in that, The vacuum heat sealing in (B) includes: first vacuum drying, then hot pressing sealing; Preferably, the vacuum drying temperature for the first vacuum heat sealing is 50~80℃, the time is 12~48 h, and the vacuum degree is -0.09~-0.1MPa; Preferably, the hot-press sealing pressure of the single vacuum heat sealing is 0.2~0.5MPa, and the time is 1~10s.

7. The packaging method for an all-solid-state battery cell according to claim 6, characterized in that, The vacuum drying temperature for the first vacuum heat sealing is 60℃, the vacuum drying time is 24 h, and the vacuum degree is -0.095MPa. The heat sealing pressure for the first vacuum heat sealing is 0.3 MPa, and the heat sealing time is 8 seconds.

8. The packaging method for an all-solid-state battery cell according to claim 1, characterized in that, The isostatic pressing method described in (B) includes: Apply a pressure of 200 to 800 MPa to the battery cell after primary encapsulation, hold the pressure for 10 to 30 minutes, and then release the pressure to complete the isostatic pressing process.

9. The packaging method for an all-solid-state battery cell according to claim 1, characterized in that, The secondary vacuum heat sealing in (C) includes: first vacuum drying, and then hot pressing sealing; Preferably, the vacuum drying temperature of the secondary vacuum heat sealing is 50~80℃, the time is 12~48 h, and the vacuum degree is -0.09~-0.1MPa; Preferably, the hot-pressing pressure of the secondary vacuum heat sealing is 0.2~0.5MPa, and the time is 1~10s.

10. A solid-state battery cell, characterized in that, The all-solid-state battery cell is mainly obtained by the packaging method described in any one of claims 1 to 9.

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