Solid-state polymer electrolyte and preparation method and application thereof
By introducing NH2-Zr/MOFs and Zr/MOFs porous materials into solid polymer electrolytes, electrode interface defects are dynamically repaired, solving the problems of poor contact and interfacial impedance in traditional solid polymer electrolytes, and improving the cycle life and ionic conductivity of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING ELECTRIC VEHICLE
- Filing Date
- 2026-05-19
- Publication Date
- 2026-07-31
AI Technical Summary
Traditional solid polymer electrolytes suffer from poor initial contact at the electrode-to-electrode interface, microcracks caused by electrode volume expansion and contraction, increased interfacial impedance, and a contradiction between ionic conductivity and mechanical strength, resulting in insufficient cycle life. Existing self-healing systems have stringent repair conditions and struggle to balance ionic conductivity and self-healing performance.
By introducing NH2-Zr/MOFs into the polymer electrolyte, the covalent and hydrogen bonds of the polymer segments are dynamically rearranged to self-heal electrode interface defects. Zr/MOFs porous materials are added to reduce ion conduction impedance. A stable solid-solid interface contact is formed by combining polyether-urethane-based polymer materials with zirconium-based porous organic framework materials.
It significantly reduces the ion conduction impedance at the electrode interface, improves battery cycle life, enhances electrode interface stability and ion conductivity, and extends battery cycle life.
Smart Images
Figure CN122494790A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery technology, and more specifically, relates to a solid polymer electrolyte, its preparation method, and its application. Background Technology
[0002] Solid polymer electrolytes are a core component of next-generation high-safety lithium batteries, but their practical applications face numerous bottlenecks that hinder commercialization. Traditional solid polymer electrolytes suffer from poor initial contact in their solid-solid contact with electrodes. During charging and discharging, the expansion and contraction of the electrode volume leads to microcracks and delamination in the electrolyte layer, resulting in increased interfacial impedance. Furthermore, there is a seesaw effect between ionic conductivity and mechanical strength, and the cycle life is far from meeting commercial requirements.
[0003] To address these issues, the academic community has proposed various solutions, such as applying external pressure to improve interfacial contact, coating the electrode surface with a coating to modify the interface, introducing inorganic fillers for composite reinforcement, in-situ polymerization to form an electrolyte layer, and adding plasticizers to improve conductivity. However, these solutions all have limitations. They cannot dynamically repair interfacial defects generated during cycling and may also increase structural complexity, increase manufacturing costs, or sacrifice battery safety.
[0004] Dynamic polymer electrolytes with self-healing capabilities have emerged as a promising area of innovation. Through dynamic covalent and non-covalent interactions, they can spontaneously repair electrolyte defects, buffer electrode volume change stress, and improve battery cycle stability. However, existing self-healing systems still suffer from drawbacks such as stringent repair conditions and the difficulty in simultaneously achieving ionic conductivity and self-healing performance. Summary of the Invention
[0005] The purpose of this invention is to provide a solid polymer electrolyte, its preparation method, and its applications. In this solid polymer electrolyte, the covalent bonds of the polymer segments and the hydrogen / chemical bonds between the polyurethane groups can dynamically rearrange, spontaneously repairing interface defects that occur during charge-discharge cycles, ensuring stable solid-solid interface contact, and improving battery cycle life. Furthermore, by adding NH2-Zr / MOFs, the solid polymer electrolyte of this invention can reduce the ion conductivity impedance at the solid-solid interface of the electrode.
[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a solid polymer electrolyte, the method comprising: (1) Dissolve zirconium chloride and 2,4-dihydroxybenzoic acid in a first solvent, then add tris(2-chloropropyl) phosphate and water, stir until homogeneous, and obtain a solution; finally, subject the solution to a hydrothermal reaction to obtain Zr / MOFs; (2) The Zr / MOFs, 4-aminobenzoic acid and the second solvent are stirred and mixed evenly, and then the reaction is carried out to obtain NH2-Zr / MOFs; (3) In the presence of a protective gas, polyethylene glycol, disulfide organic monomers, hexamethylene diisocyanate and the NH2-Zr / MOFs are dissolved in a third solvent, and then dibutyltin dilaurate is added to obtain a mixed solution; finally, the mixed solution is stirred for the first time, and the second solvent is added periodically during the first stirring. After the first stirring is completed, a second stirring is performed to obtain Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product (abbreviated as PEG-PU(SS)-Zr / MOFs); (4) The Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product, lithium bis(fluorosulfonyl)imide and the second solvent are mixed evenly, then cast into a mold and dried to obtain the solid polymer electrolyte.
[0007] According to the present invention, preferably, in step (1), The amounts of zirconium chloride, 2,4-dihydroxybenzoic acid, tris(2-chloropropyl) phosphate, and water added relative to 7-33 ml of the first solvent are 100-370 mg, 0.5-5 g, 20-155 mg, and 2-200 ml, respectively. The hydrothermal reaction is carried out at a temperature of 100~180℃ for 12~40 hours. The first solvent is N,N-dimethylformamide.
[0008] According to the present invention, preferably, in step (2), the amounts of Zr / MOFs and 4-aminobenzoic acid added are 3-50 mg and 1-7 g, respectively, relative to 20-85 ml of the second solvent; The reaction is carried out at a temperature of 100~220℃ for 18~48 hours. The second solvent is N,N-dimethylacetamide.
[0009] According to the present invention, preferably, in step (3), the disulfide organic monomer is at least one of bis(2-hydroxyethyl) disulfide (DTBO), 2,2'-diaminodiphenyl disulfide (DTDA), and cystamine (CYST); The weight-average molecular weight (Mw) of the polyethylene glycol is 3 × 10⁻⁶. 3 <Mw<6×10 6 ; The protective gas is nitrogen and / or argon; The third solvent is dichloromethane.
[0010] According to the present invention, preferably, in step (3), the amounts of polyethylene glycol, disulfide organic monomers, hexamethylene diisocyanate, NH2-Zr / MOFs and dibutyltin dilaurate added relative to 2-29 ml of the third solvent are 0.5-9 g, 0.5-30 mg, 230-980 μl, 2-10 mg and 2-5 μl, respectively; The temperature of the first stirring is 25~90℃, and the time is 2~12 hours; During the first stirring period, the second solvent is added once every 1 to 3 hours, with each addition being 1 to 10 ml. The second stirring temperature is 25~90℃, and the time is 6~15 hours.
[0011] According to the present invention, preferably, in step (4), the mass ratio of the Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product to lithium bis(fluorosulfonyl)imide salt is (1-5):1; The mixing time is 3 to 24 hours.
[0012] In this invention, preferably, in step (4), the amount of the second solvent added is 50ml~100ml.
[0013] As a preferred embodiment, the preparation method of the present invention includes the following steps: Step 1: First, dissolve ZrCl4 (zirconium chloride) and DHBA (2,4-dihydroxybenzoic acid) in DMF (N,N-dimethylformamide). Then add TCPP (tris(2-chloropropyl) phosphate) and deionized water (H2O), and stir thoroughly. Transfer the solution to a hydrothermal reactor for heating. After the reaction is complete, allow it to cool naturally, and centrifuge the product to obtain Zr / MOF.
[0014] Step 2: The Zr / MOFs, PABA (4-aminobenzoic acid), and DMAC (N,N-dimethylacetamide) were thoroughly stirred until homogeneous. The solution was transferred to a hydrothermal reactor and heated. After the reaction was completed, the mixture was allowed to cool naturally. The product was centrifuged and washed several times with DMAC to obtain modified NH2-Zr / MOFs.
[0015] Step 3: Under a nitrogen atmosphere, PEG (polyethylene glycol, molecular weight), disulfide organic monomers, HMDI (hexamethylene diisocyanate), and Zr / MOFs are dissolved in CH2Cl2 (dichloromethane). After thorough mixing, DBTDL (dibutyltin dilaurate) is added dropwise. The mixture is then subjected to a first stirring, with the second solvent added periodically during this first stirring. After the first stirring is complete, a second stirring is performed to obtain the Zr / MOFs-modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product (abbreviated as PEG-PU(SS)-Zr / MOFs). Step 4: PEG-PU(SS)-Zr / MOFs and LiFSI (lithium bisfluorosulfonylimide salt) are stirred and mixed evenly in DMAC. The resulting solution is cast into a polytetrafluoroethylene mold and dried in a vacuum oven at 70°C for 48 hours to remove air bubbles and volatile impurities, finally obtaining the polymer electrolyte (SPE).
[0016] A second aspect of the present invention provides a solid polymer electrolyte prepared by the above-described preparation method.
[0017] A third aspect of the present invention provides the application of the above-described solid polymer electrolyte as a separator between the positive and negative electrodes in a battery cell.
[0018] According to the present invention, preferably, when the battery cell includes a plurality of positive electrode plates and negative electrode plates, a separator of the solid polymer electrolyte is provided between each positive electrode plate and each negative electrode plate.
[0019] According to the present invention, preferably, the battery cell is manufactured by a method comprising the following steps: assembling a positive electrode, a negative electrode, and the solid polymer electrolyte into a stacked core in a "Z" shaped stacking manner, and then performing a hot pressing treatment to obtain the battery cell.
[0020] The technical solution of the present invention has the following beneficial effects: The polymer electrolyte of this invention has a molecular chain segment with abundant functional groups and chemical bonding sites, which can effectively anchor it to the surface / interface of the positive / negative electrode active material layer. Simultaneously, it can act as a non-conductive separator to firmly bond the electrode sheets. The hydrogen bonds and chemical bonds between the covalent sulfide bonds and polyurethane groups in the internal framework can dynamically rearrange and self-repair, significantly reducing the ion conduction impedance at the electrode "solid-solid" interface.
[0021] The Zr / MOF porous polymer electrolyte of this invention, when used as an aggregate filler in polymer materials, provides long-term support for flexible polymer chains, preventing damage to the interconnected pores of the polymer material due to expansion / contraction stress during cycling. Furthermore, its unique morphology provides a high specific surface area, which can enhance the reaction rate of the lithium salt desolvation process, thus extending the charge / discharge cycle life of the electrode. Simultaneously, the amine-modified MOFs exhibit better interfacial compatibility, reducing the ion conduction impedance at the electrode solid-solid interface.
[0022] The zirconium-based porous organic framework material contained in the polymer electrolyte of this invention, after amine-NH2 grafting modification (hereinafter abbreviated as NH2-Zr / MOFs), can crosslink with the disulfide / carbamate bonds of polymer segments and become a hydrogen bond donor / acceptor. This strong interfacial bonding helps stress transfer and suppresses lithium dendrites caused by interfacial defects. Moreover, the surface potential of MOFs changes after amine modification, and the electrostatic interaction between MOFs and polymer segments improves the dispersion uniformity of Zr / MOFs in the polymer matrix, prevents nanoparticle aggregation, achieves a more efficient ion conduction pathway, and reduces electrode interfacial polarization.
[0023] This invention involves preparing a polymer electrolyte comprising a polyether-urethane-based polymer and a zirconium-based porous organic framework, which is then bonded to the surface of the positive or negative electrode to replace a traditional separator. Through stacking and hot-pressing processes, the polymer electrolyte forms a stable solid-solid interface with the positive / negative electrode active material layers, improving the cycle life of semi-solid-state batteries.
[0024] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0025] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.
[0026] Figure 1 A schematic structural diagram of a stacked core according to an embodiment or comparative example of the present invention is shown.
[0027] Figure 2 An AC impedance curve of an assembled battery according to a test example of the present invention is shown.
[0028] Figure 3 A comparison graph of the cycle performance of an assembled battery according to a test example of the present invention is shown, where Capacity Retention is the capacity retention rate and Cycles is the number of cycles.
[0029] Explanation of reference numerals in the attached figures: 1. Negative electrode 2. Solid polymer electrolyte 3. Positive electrode Detailed Implementation
[0030] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
[0031] The present invention is further illustrated by the following examples: In the following examples and comparative examples: the PVDF adhesive used is Solef5130 from Shanghai Youqia, and the SBR adhesive used is TRD104A from Shanghai Huiping.
[0032] Example 1
[0033] Preparation of polymer electrolytes: (1) Dissolve 100 mg ZrCl4 (zirconium chloride) and 2.5 g DHBA (2,4-dihydroxybenzoic acid) in 20 ml DMF (N,N-dimethylformamide) and stir magnetically. Then, add 100 mg TCPP (tris(2-chloropropyl) phosphate) and 90 ml deionized water and stir for 30 minutes to obtain a solution. Then transfer the solution to a hydrothermal reactor and heat at 120 °C for 24 hours. Centrifuge to obtain Zr / MOFs. Then, mix 4 mg Zr / MOFs, 5.0 g PABA (4-aminobenzoic acid) and 50 ml DMAC (N,N-dimethylacetamide) evenly, then transfer to a hydrothermal reactor and heat at 180 °C for 24 hours. Finally, centrifuge and wash several times with DMAC to obtain NH2-Zr / MOFs.
[0034] (2) Under a N2 atmosphere, 3.0 g of PEG (polyethylene glycol, molecular weight Mw is 5×10) was added. 47.7 mg DTBO (di(2-hydroxyethyl) disulfide), 780 μl HMDI (hexamethylene diisocyanate), and 5.0 mg NH2-Zr / MOFs were dissolved in 5 ml CH2Cl2 (dichloromethane). After complete dissolution, 3 μl DBTDL (dibutyltin dilaurate) was added dropwise to the above solution. After the addition was complete, a mixed solution was obtained. The mixed solution was stirred at 45 °C for 6 hours. Every 2 hours, 3.5 ml DMAC was added to the reaction mixture. After stirring for 6 hours, stirring was continued at 45 °C for 12 hours. After the reaction was completed, Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product (abbreviated as PEG-PU(SS)-Zr / MOFs) was obtained. PEG-PU(SS)-Zr / MOFs and LiFSI were mixed in 80 ml DMAC at a mass ratio of 2:1 and stirred for 6 hours to ensure uniform mixing of all components. Finally, the uniformly stirred viscous liquid was cast into a polytetrafluoroethylene mold and dried in a vacuum oven at 70°C for 48 hours to remove air bubbles and volatile impurities from the liquid, ultimately obtaining a polymer electrolyte (SPE) with a thickness of 30 μm.
[0035] Comparative Example 1
[0036] Under a nitrogen atmosphere, 3.0 g of PEG (polyethylene glycol, molecular weight Mw is 5 × 10⁻⁶) was added. 4 7.7 mg DTBO (di(2-hydroxyethyl) disulfide) and 780 μl HMDI (hexamethylene diisocyanate) were dissolved in 5 ml CH2Cl2 (dichloromethane). After complete dissolution, 3 μl DBTDL (dibutyltin dilaurate) was added dropwise to the above solution. After the addition was complete, a mixed solution was obtained. The mixed solution was stirred at 45 °C for 6 hours. Every 2 hours, 3.5 ml DMAC was added to the reaction mixture. After stirring for 6 hours, stirring was continued at 45 °C for 12 hours. After the reaction was completed, a poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product (abbreviated as PEG-PU(SS)) was obtained. PEG-PU (SS) and LiFSI were mixed in 80 ml of DMAC at a mass ratio of 2:1 and stirred for 6 hours to ensure that the components were mixed evenly. Finally, the well-stirred viscous liquid was poured into a polytetrafluoroethylene mold and dried in a vacuum oven at 70°C for 48 hours to remove air bubbles and volatile impurities from the liquid, and finally a polymer electrolyte (SPE) with a thickness of 30 μm was obtained.
[0037] Comparative Example 2
[0038] The polymer electrolyte was prepared according to the method of Example 1, except that in step (1), the step of preparing NH2-Zr / MOFs was removed; and in step (2), NH2-Zr / MOFs was replaced with Zr / MOFs.
[0039] Comparative Example 3
[0040] The solid polymer electrolyte used in this comparative example is a commercially available PP / PE / PP membrane (Celgard 2325).
[0041] Test case
[0042] Batteries were prepared using the solid polymer electrolytes prepared in the above embodiments and comparative examples, respectively. The specific preparation methods are as follows: (1) Preparation of positive electrode sheet: The positive electrode active material LiNi 0.8 Mn 0.1 Co 0.1 O2 (S8303, Ronbay Technology) was dispersed and mixed with conductive carbon black SP, conductive carbon nanotubes (CNTs) (LB122, Jiangsu Tiannai), and binder PVDF at a mass ratio of 97:1.2:0.5:1.3. The mixture was then stirred at high speed with organic solvent NMP added, and the viscosity was adjusted to 5000 mPa·s and the solid content to 75%. After high-speed stirring, vacuum defoaming was performed in a mixing tank to obtain a uniformly dispersed positive electrode slurry. The positive electrode slurry was coated onto both sides of a 13 μm aluminum foil using a coating machine. After drying, rolling, slitting, and die-cutting, positive electrode sheets of the required dimensions were produced. The areal density of the positive electrode layer coated on each side was 190 g / m². 2 The compacted density is 3.55 g / cm³. 3 .
[0043] (2) Preparation of negative electrode sheet: The negative electrode active material graphite, conductive carbon black SP, binder SBR and thickener CMC are dispersed and mixed in a mass ratio of 96.5:1.2:1.5:0.8. Deionized water is added and the mixture is stirred at high speed and the viscosity is adjusted to 4000 mPa. With a solids content of 53%, the mixture was vacuum defoamed in a mixing tank after high-speed stirring to obtain a uniformly dispersed negative electrode slurry. The negative electrode slurry was then coated onto both sides of a 6μm copper foil using a coating machine. After drying, rolling, slitting, and die-cutting, it was produced into negative electrode sheets of the required dimensions. The areal density of the negative electrode layer coated on each side was 140 g / m². 2 The compacted density is 1.6 g / cm³. 3 .
[0044] (3) Battery fabrication: The positive electrode 3, the negative electrode 1, and the solid polymer electrolyte 2 are assembled into a stack in a "Z" shaped stacking manner (e.g., ...). Figure 1As shown, the stacked cores are hot-pressed at 90℃ and then ultrasonically welded to the tabs. The welded stacked cores are then placed in an aluminum-plastic film for top / side sealing, with injection ports and gas bags pre-installed. Electrolyte is injected at an injection rate of 1.8 g / Ah (based on the total weight of the electrolyte, the electrolyte includes: lithium salt LiPF6 13wt%, additives VC 1wt%, FEC 3wt%, DTD 2wt%, with the remainder being solvent; the solvents are EC, EMC, and DEC, EC:EMC:DEC = 1:2:1 (v / v)). After sealing, impregnation, formation, and a second sealing process involving evacuation, the battery is finally obtained.
[0045] Battery testing: Three charge / discharge cycles were performed at a 0.33C rate, followed by full charge to 50% SoC, and then EIS AC impedance testing was conducted. Cyclic testing was performed at 25℃ using a 0.5C charge (constant current-constant voltage) / 1C discharge (constant current) cycle.
[0046] according to Figure 2 The evaluation results of Example 1 and Comparative Examples 1, 2, and 3 show that Example 1 exhibits lower interfacial transport impedance and higher ionic reactivity.
[0047] according to Figure 3 The evaluation results of Example 1 and Comparative Examples 1, 2, and 3 show that Example 1 demonstrates good performance in terms of cycle capacity retention and stability.
[0048] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.
Claims
1. A method for preparing a solid polymer electrolyte, characterized in that, The preparation method includes: (1) Dissolve zirconium chloride and 2,4-dihydroxybenzoic acid in a first solvent, then add tris(2-chloropropyl) phosphate and water, stir until homogeneous, and obtain a solution; finally, subject the solution to a hydrothermal reaction to obtain Zr / MOFs; (2) The Zr / MOFs, 4-aminobenzoic acid and the second solvent are stirred and mixed evenly, and then the reaction is carried out to obtain NH2-Zr / MOFs; (3) In the presence of a protective gas, polyethylene glycol, disulfide organic monomers, hexamethylene diisocyanate and the NH2-Zr / MOFs are dissolved in a third solvent, and then dibutyltin dilaurate is added to obtain a mixed solution; finally, the mixed solution is stirred for the first time, and the second solvent is added periodically during the first stirring. After the first stirring is completed, a second stirring is performed to obtain a Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product; (4) The Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product, lithium bis(fluorosulfonyl)imide and the second solvent are mixed evenly, then cast into a mold and dried to obtain the solid polymer electrolyte.
2. The preparation method according to claim 1, wherein, In step (1), The amounts of zirconium chloride, 2,4-dihydroxybenzoic acid, tris(2-chloropropyl) phosphate, and water added relative to 7-33 ml of the first solvent are 100-370 mg, 0.5-5 g, 20-155 mg, and 2-200 ml, respectively. The hydrothermal reaction is carried out at a temperature of 100~180℃ for a duration of 12~40 hours. The first solvent is N,N-dimethylformamide.
3. The preparation method according to claim 1, wherein, In step (2), the amounts of Zr / MOFs and 4-aminobenzoic acid added are 3-50 mg and 1-7 g, respectively, relative to 20-85 ml of the second solvent; The reaction is carried out at a temperature of 100~220℃ for 18~48 hours. The second solvent is N,N-dimethylacetamide.
4. The preparation method according to claim 1, wherein, In step (3), the disulfide organic monomer is at least one of bis(2-hydroxyethyl) disulfide, 2,2'-diaminodiphenyl disulfide and cystamine; The weight-average molecular weight (Mw) of the polyethylene glycol is 3 × 10⁻⁶. 3 <Mw<6×10 6 ; The protective gas is nitrogen and / or argon; The third solvent is dichloromethane.
5. The preparation method according to claim 1, wherein, In step (3), relative to 2-29 ml of the third solvent, the amounts of polyethylene glycol, disulfide organic monomers, hexamethylene diisocyanate, NH2-Zr / MOFs and dibutyltin dilaurate added are 0.5-9 g, 0.5-30 mg, 230-980 μl, 2-10 mg and 2-5 μl, respectively; The temperature of the first stirring is 25~90℃, and the time is 2~12 hours; During the first stirring period, the second solvent is added once every 1 to 3 hours, with each addition being 1 to 10 ml. The second stirring temperature is 25~90℃, and the time is 6~15 hours.
6. The preparation method according to claim 1, wherein, In step (4), the mass ratio of the Zr / MOFs modified poly(ethylene glycol cobis(2-hydroxyethyl) disulfide cohexamethylene diisocyanate) composite product to lithium bis(fluorosulfonyl)imide salt is (1-5):1; The mixing time is 3 to 24 hours.
7. A solid polymer electrolyte prepared by the preparation method according to any one of claims 1-6.
8. The application of the solid polymer electrolyte of claim 7 as a separator between the positive and negative electrodes in a battery cell.
9. The application according to claim 8, wherein, When the battery cell includes multiple positive and negative electrode plates, a membrane of the solid polymer electrolyte is provided between each positive and negative electrode plate.
10. The application according to claim 8, wherein, The battery cell is manufactured by a method comprising the following steps: assembling a positive electrode, a negative electrode, and the solid polymer electrolyte into a stacked core in a "Z" shaped stacking manner, and then performing a hot pressing treatment to obtain the battery cell.