Solid-state battery production method

Abstract

The application relates to a solid-state battery preparation method, and belongs to the technical field of batteries.The solid-state battery preparation method comprises an electrode assembly assembling step and an ultraviolet light irradiation polymerization step.The electrode assembly assembling step comprises the following steps: laminating or winding a positive electrode sheet, a separator and a negative electrode sheet to form an electrode assembly; placing the electrode assembly into a shell; and injecting a precursor solution into the shell to obtain an electrode.The ultraviolet light irradiation polymerization step comprises the following steps: irradiating the electrode with ultraviolet light to cause in-situ polymerization of polymerizable monomers to form a solid-state electrolyte film, thereby eliminating the independent preparation step of the solid-state electrolyte film, reducing the manufacturing cost and manufacturing time of the solid-state battery, and ensuring the interface contact between the electrode and the solid-state electrolyte film, reducing the interface impedance, reducing the point contact between the electrode and the solid-state electrolyte film, ensuring the smoothness of the ion transmission channel, and improving the cycle capacity retention rate and rate performance of the solid-state battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for preparing a solid-state battery. Background Technology

[0002] Current solid-state battery fabrication methods mostly adopt a "preparation-then-assembly" approach, where the positive electrode, negative electrode, and solid electrolyte membrane are prepared separately, and then the three are stacked and subjected to hot pressing and other treatments. This fabrication method results in complex processes, high manufacturing costs, and high interfacial impedance due to poor contact at the rigid solid-solid interface between the electrode and the solid electrolyte membrane. Summary of the Invention

[0003] In view of this, this application provides a method for preparing a solid-state battery that can reduce the cross-sectional impedance between the solid electrolyte membrane and the electrode.

[0004] This application provides a method for preparing a solid-state battery, characterized by comprising:

[0005] Cell assembly:

[0006] The positive electrode, separator and negative electrode are stacked or wound to form a cell assembly, and the cell assembly is placed in the housing;

[0007] The precursor solution is injected into the casing to obtain the battery cell. The precursor solution, by mass percentage, is a mixture of 60wt%–80wt% polymerizable monomers, 15wt%–25wt% lithium salt, 1wt%–3wt% photoinitiator, 0wt%–5wt% filler, and 0.5wt%–2wt% interface stabilizer, with the sum of all components being 100wt%.

[0008] Ultraviolet light aggregation:

[0009] The cell is irradiated with ultraviolet light, causing the polymerizable monomers to undergo in-situ polymerization to form a solid electrolyte membrane.

[0010] Optionally, the step of irradiating the battery cell with ultraviolet light includes: at 100mW / cm 2 ~150mW / cm 2 The battery cell is irradiated with ultraviolet light at a light intensity of 60s to 120s.

[0011] Optionally, the value is 100mW / cm 2 ~150mW / cm 2 Following the step of irradiating the battery cell with ultraviolet light at a light intensity of 10mW / cm², the method further includes: 2 ~30mW / cm 2 The battery cell is irradiated with ultraviolet light at a light intensity of 5 to 15 minutes.

[0012] Optionally, the polymerizable monomer is selected from one or more of methyl acrylate, ethyl acrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0013] Optionally, the polymerizable monomer is selected from any two of methyl acrylate, ethyl acrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate; the mass ratio of any two polymerizable monomers is 1:(1.5~4).

[0014] Optionally, the lithium salt is selected from one or more of lithium bisfluorosulfonylimide and lithium bistrifluoromethanesulfonylimide.

[0015] Optionally, the photoinitiator is selected from one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0016] Optionally, the filler is selected from one or more of alumina, lithium lanthanum zirconium oxide, lithium lanthanum titanate, lithium aluminum titanium phosphate, lithium nitride, and silicon dioxide.

[0017] Optionally, the interface stabilizer is selected from one or more of vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, 1,3-propane sulcolone, and lithium bis(oxalate)borate.

[0018] Optionally, in the step of injecting the precursor solution into the housing, after injection, the solution is maintained at a pressure of 0.3MPa~0.8MPa for 2h~6h to allow the precursor solution to wet the cell assembly.

[0019] Optionally, the wavelength of the ultraviolet light is 320nm~395nm.

[0020] Optionally, in the ultraviolet light polymerization step, the incident direction of the ultraviolet light is parallel to the thickness direction of the battery cell assembly; the housing has two surfaces that are arranged opposite to each other along the thickness direction of the battery cell assembly, and the ultraviolet light irradiates the two surfaces respectively.

[0021] Optionally, the value is 100mW / cm 2 ~150mW / cm 2In the step of irradiating the battery cell with ultraviolet light, the incident direction of the ultraviolet light is parallel to the thickness direction of the battery cell assembly. The ultraviolet light irradiates two surfaces of the housing that are arranged opposite to each other along the thickness direction of the battery cell assembly, and the incident direction of the ultraviolet light is perpendicular to the plane of the irradiated surface.

[0022] Optionally, the value is 10mW / cm 2 ~30mW / cm 2 In the step of irradiating the battery cell with ultraviolet light, the ultraviolet light irradiates two surfaces of the housing that are arranged opposite each other along the thickness direction of the battery cell assembly; the incident direction of the ultraviolet light is perpendicular to the plane of the irradiated surface, or the angle between the incident direction of the ultraviolet light and the plane of the irradiated surface is 15°~45°.

[0023] This application provides a method for preparing a solid-state battery. The method includes a cell assembly step and an ultraviolet (UV) irradiation polymerization step. The cell assembly step includes: stacking or winding a positive electrode, a separator, and a negative electrode to form a cell assembly; placing the cell assembly into a housing; and injecting a precursor solution into the housing to obtain a cell. The precursor solution is formed by mixing polymerizable monomers, lithium salts, photoinitiators, fillers, and interface stabilizers by mass percentage. The UV irradiation polymerization step includes: irradiating the cell with ultraviolet light, causing the polymerizable monomers to undergo in-situ polymerization to form a solid-state electrolytic cell. The precursor electrolyte membrane is injected after the battery cell assembly is completed. After injection, ultraviolet light polymerization is used to cause the polymerizable monomers in the precursor liquid to undergo in-situ polymerization to form a solid electrolyte membrane. This eliminates the need for a separate solid electrolyte membrane preparation step, reducing the manufacturing cost and time of solid-state batteries. Moreover, the solid electrolyte membrane is formed by ultraviolet light polymerization, which ensures interfacial contact between the electrode and the solid electrolyte membrane, reduces interfacial impedance, reduces point contact between the electrode and the solid electrolyte membrane, ensures the smoothness of ion transport channels, and improves the cycle capacity retention and rate performance of solid-state batteries. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the solid-state battery fabrication method provided in the embodiments of this application. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] In the description of this application, "a plurality of" means two or more, unless otherwise expressly specified. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more features.

[0027] In the description of this application, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from others, as long as the purpose of the process can be achieved. Furthermore, in this specification, the numerical range indicated by "~" represents a range where the values ​​before and after the "~" are respectively the minimum and maximum values. Additionally, in this specification, the term "layer," when viewed in a plan view, includes not only the shape formed on the entire surface but also the shape formed on a portion of the surface.

[0028] The following disclosure provides many different implementations or examples for carrying out different structures of this application. To simplify the disclosure of this application, the components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit this application.

[0029] In some embodiments of this application, a method for preparing a solid-state battery is provided, characterized by comprising:

[0030] S100, Cell Assembly:

[0031] S101. The positive electrode, separator and negative electrode are stacked or wound to form a cell assembly, and the cell assembly is placed in the housing;

[0032] S102. The precursor solution is injected into the casing to obtain the battery cell. By mass percentage, the precursor solution is formed by mixing 60wt%~80wt% of polymerizable monomers, 15wt%~25wt% of lithium salts, 1wt%~3wt% of photoinitiator, 0wt%~5wt% of filler, and 0.5wt%~2wt% of interface stabilizer, with the sum of all components being 100wt%.

[0033] S200, UV light aggregation:

[0034] S201. The battery cell is irradiated with ultraviolet light, causing the polymerizable monomers to undergo in-situ polymerization to form a solid electrolyte membrane.

[0035] Current solid-state battery fabrication methods mostly employ a "preparation-then-assembly" approach, where the positive electrode, negative electrode, and solid electrolyte membrane are prepared separately, then stacked and subjected to hot pressing and other treatments. This fabrication method has the following drawbacks:

[0036] Complex process: It requires a separate solid electrolyte membrane preparation step, which increases the manufacturing equipment and time costs of solid electrolyte membranes.

[0037] Poor interfacial contact: The preparation method of stacking the positive electrode, negative electrode and solid electrolyte membrane and then hot-pressing them results in poor microscopic contact between the electrode and the solid electrolyte membrane, regardless of the hot-pressing pressure. There are a lot of point contacts, which leads to poor ion transport channels and high interfacial impedance.

[0038] Mechanical stress: The rigid solid-solid interface between the electrode and the solid electrolyte membrane causes the electrode materials, such as the positive active material in the positive electrode and the negative active material in the negative electrode, to expand in volume during charging and discharging, compressing the solid electrolyte membrane. When the electrode contracts, the area that was originally in close contact due to expansion may shrink back, leaving tiny gaps. After multiple cycles, this repeated expansion and contraction causes the contact points to gradually loosen and detach, leading to separation from the solid electrolyte membrane and interface failure. This results in capacity decay and a shortened lifespan of the solid-state battery.

[0039] The solid-state battery preparation method provided in this application includes a cell assembly step and an ultraviolet light polymerization step. The cell assembly step includes: stacking or winding a positive electrode sheet, a separator, and a negative electrode sheet to form a cell assembly; placing the cell assembly into a housing; and injecting a precursor solution into the housing to obtain a cell. The precursor solution, by mass percentage, is formed by mixing polymerizable monomers, lithium salts, photoinitiators, fillers, and interface stabilizers. The ultraviolet light polymerization step includes: irradiating the cell with ultraviolet light, causing the polymerizable monomers to undergo an in-situ polymerization reaction to form a solid electrolyte membrane. After the battery cell is assembled, a precursor liquid is injected. After injection, ultraviolet light polymerization is used to cause the polymerizable monomers in the precursor liquid to undergo in-situ polymerization to form a solid electrolyte membrane. This eliminates the need for a separate solid electrolyte membrane preparation step, reducing the manufacturing cost and time of solid-state batteries. Moreover, the solid electrolyte membrane is formed by ultraviolet light polymerization, which ensures interfacial contact between the electrode and the solid electrolyte membrane, reduces interfacial impedance, reduces point contact between the electrode and the solid electrolyte membrane, ensures the smoothness of ion transport channels, and improves the cycle capacity retention and rate performance of solid-state batteries.

[0040] Specifically, under ultraviolet light irradiation, the photoinitiator in the precursor solution can ensure the speed at which polymerizable monomers undergo in-situ polymerization due to photoinitiation to form polymers, shorten the reaction time, and improve preparation efficiency.

[0041] The addition of interface stabilizers to the precursor solution can ensure the formation of a stable positive electrolyte interface film between the solid electrolyte membrane and the positive electrode, and a stable solid electrolyte interface film between the solid electrolyte membrane and the negative electrode. It can also actively maintain close contact and ion transport stability at the interface during cycling, transforming the fragile "point contact" between the solid electrolyte membrane and the electrode into a robust and durable "surface contact".

[0042] The preparation methods for solid-state batteries also include:

[0043] After S300 and ultraviolet irradiation polymerization are completed, the cells undergo standard processes such as hot pressing, formation, aging, and capacity testing to obtain solid-state batteries.

[0044] In some embodiments, the step of irradiating the battery cell with ultraviolet light includes:

[0045] S202, at 100mW / cm 2 ~150mW / cm 2 The battery cell is irradiated with ultraviolet light at an intensity of 100 mW / cm² for 60-120 seconds. Specifically, the irradiation intensity can be 100 mW / cm². 2 105mW / cm 2 110mW / cm 2 115mW / cm 2 120mW / cm 2 125mW / cm 2 130mW / cm 2 135mW / cm 2 140mW / cm 2 145mW / cm 2 150mW / cm 2 The irradiation duration can be any value from the range of 60s, 70s, 80s, 90s, 100s, 110s, and 120s, or any value from the range of any two values. At 100mW / cm² 2 ~150mW / cm 2 The method of irradiating the battery cell with ultraviolet light for 60s~120s allows the polymerizable monomers in the precursor solution injected into the shell to undergo in-situ polymerization reaction in a short time to form a polymer, thereby forming the skeleton of the solid electrolyte membrane and ensuring the stability of the solid electrolyte membrane.

[0046] In some embodiments, at 100mW / cm 2 ~150mW / cm 2 Following the step of irradiating the battery cell with ultraviolet light, the process also includes:

[0047] S203, at 10mW / cm 2 ~30mW / cm 2 The battery cell is irradiated with ultraviolet light at an intensity of 10 mW / cm² for 5 to 15 minutes. 2 15mW / cm 2 20mW / cm 2 25mW / cm 2 30mW / cm 2 The irradiation duration can be any value from the range of 5 min, 7 min, 9 min, 11 min, 13 min, and 15 min, or any value from the range of any two values.

[0048] At 100mW / cm 2 ~150mW / cm 2 After irradiating the battery cell with ultraviolet light, the light intensity was reduced to 10mW / cm². 2 ~30mW / cm 2 Extending the irradiation time to 5-15 minutes allows the interface regions with weak polymerization due to electrode shielding to fully complete polymerization, reducing internal stress and achieving interface integration.

[0049] Specifically, at 100mW / cm 2 ~150mW / cm 2 After irradiating the battery cell with ultraviolet light at a certain intensity, the polymerizable monomers in the precursor solution below the electrode framework or in the deep pores may not polymerize completely due to insufficient light. (At 10mW / cm²) 2 ~30mW / cm 2 Irradiating the battery cell with ultraviolet light for 5 to 15 minutes allows the ultraviolet light to penetrate or scatter into these areas, triggering in-situ polymerization of residual polymerizable monomers. This forms a continuous and dense polymer composite interface layer between the electrode and the solid electrolyte membrane. The thorough and uniform polymerization ensures even stress distribution, improving the overall toughness of the interface layer and its adhesion to the electrode.

[0050] In some embodiments, the polymerizable monomer is selected from one or more of methyl acrylate, ethyl acrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. The polymerizable monomer is selected from the multifunctional acrylate monomers described above, such that the polymerizable monomer contains multiple acrylate groups. Under ultraviolet light initiation, these acrylate groups can undergo in-situ polymerization in a short time to form a highly cross-linked three-dimensional network polymer with high mechanical strength and rigidity, effectively resisting the stress caused by volume changes due to electrode shrinkage and expansion, and preventing the interface layer from cracking.

[0051] In some embodiments, the polymerizable monomer is methyl acrylate.

[0052] In some embodiments, the polymerizable monomer is ethyl acrylate.

[0053] In some embodiments, the polymerizable monomer is tripropylene glycol diacrylate.

[0054] In some embodiments, the polymerizable monomer is 1,6-hexanediol diacrylate.

[0055] In some embodiments, the polymerizable monomer is trimethylolpropane triacrylate.

[0056] In some embodiments, the polymerizable monomer is pentaerythritol triacrylate.

[0057] In some embodiments, the polymerizable monomer is pentaerythritol tetraacrylate.

[0058] In some embodiments, the polymerizable monomer is dipentaerythritol pentaacrylate.

[0059] In some embodiments, the polymerizable monomer is dipentaerythritol hexaacrylate.

[0060] In some embodiments, the polymerizable monomers are selected from any two of methyl acrylate, ethyl acrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, and the mass ratio of any two polymerizable monomers is 1:(1.5~4). Specifically, the mass ratio of any two polymerizable monomers can be any ratio from 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or any ratio within the range of any two ratios. When two multifunctional acrylate monomers are selected as polymerizable monomers and the mass ratio of the two acrylate monomers is in the range of 1:(1.5~4), good fluidity and wettability can be obtained in the precursor solution, ensuring the initial interfacial contact between the precursor solution and the electrode. After solidification by in-situ polymerization reaction under ultraviolet light, a polymer matrix with both high rigidity and flexibility can be formed, which can resist shear stress and buffer stress through micro-deformation, thereby achieving long-term stable interfacial integration.

[0061] In some embodiments, the lithium salt includes one or more of lithium bisfluorosulfonylimide and lithium bistrifluoromethanesulfonylimide.

[0062] In some embodiments, the lithium salt is lithium bisfluorosulfonylimide.

[0063] In some embodiments, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide.

[0064] In some embodiments, the photoinitiator is selected from one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone. Using the photoinitiator described above enhances the penetration of ultraviolet light, enabling it to effectively penetrate the pores or microscopic obstructions of the electrode material. This ensures that the precursor, even when obscured by shadowed areas, can fully polymerize. Furthermore, it allows for compatibility with UV-LED light sources, with absorption peaks highly matching those of widely used industrial UV-LED light sources at 365nm, 385nm, 395nm, and 405nm. This makes the process easy to integrate into production lines, and LED light sources offer advantages such as low energy consumption, long lifespan, and low heat generation.

[0065] In some embodiments, the photoinitiator is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0066] In some embodiments, the photoinitiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

[0067] In some embodiments, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0068] In some embodiments, the photoinitiator comprises diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-1-propanone in a mass ratio of 1:(0.5~1.5).

[0069] The mass ratio of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide to 2-hydroxy-2-methyl-1-phenyl-1-propanone is 1:1.

[0070] In some embodiments, the filler is selected from one or more of alumina, lithium lanthanum zirconium oxide, lithium lanthanum titanate, lithium aluminum titanium phosphate, lithium nitride, and silicon dioxide. Using the nano-ceramic filler described above as a rigid support point can significantly improve the Young's modulus, hardness, and puncture resistance of the interface layer after UV curing, and effectively inhibit the growth of lithium dendrites.

[0071] In some embodiments, the filler is alumina.

[0072] In some embodiments, the filler is lithium lanthanum zirconium oxide.

[0073] In some embodiments, the filler is lithium lanthanum titanate.

[0074] In some embodiments, the filler is lithium aluminum titanium phosphate.

[0075] In some embodiments, the filler is lithium nitride.

[0076] In some embodiments, the filler is silicon dioxide.

[0077] In some embodiments, the interface stabilizer is selected from one or more of vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, 1,3-propane sulcolone, and lithium bis(oxalate)borate. Interface stabilizers selected from the above description can ensure the formation of a stable positive electrode electrolyte interface film between the solid electrolyte membrane and the positive electrode, and a stable solid electrolyte interface film between the solid electrolyte membrane and the negative electrode. Furthermore, they can actively maintain close contact and ion transport stability at the interface during cycling, transforming the fragile "point contact" between the solid electrolyte membrane and the electrode into a robust and durable "surface contact."

[0078] In some embodiments, the interface stabilizer is vinylene carbonate.

[0079] In some embodiments, the interface stabilizer is fluoroethylene carbonate.

[0080] In some embodiments, the interface stabilizer is ethylene carbonate.

[0081] In some embodiments, the interface stabilizer is 1,3-propanesulfonyl lactone.

[0082] In some embodiments, the interface stabilizer is lithium bis(oxalate)borate.

[0083] In some embodiments, during the step of injecting the precursor solution into the housing, after injection, the solution is maintained at a pressure of 0.3 MPa to 0.8 MPa for 2 to 6 hours to allow the precursor solution to wet the cell assembly. Specifically, the pressure can be any value from 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, and 0.8 MPa, or any value within a range of any two values. The maintenance time can be any value from 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours, or any value within a range of any two values. The precursor solution is formed by mixing polymerizable monomers, lithium salts, photoinitiators, fillers, and interface stabilizers. This results in a high viscosity of the precursor solution, which is difficult to completely and quickly fill the pores on the electrode surface by capillary action alone under normal pressure. It is very easy to leave pores and form initial defects. However, after the precursor solution is injected, it is kept at a pressure of 0.3MPa~0.8MPa for 2h~6h, which can significantly enhance the capillary force, drive the precursor solution into submicron or even nanoscale pores, and overcome the surface tension of the precursor solution and the gas resistance in the pores, expelling the gas. This allows the precursor solution to adhere tightly to the uneven surface of the electrode without damaging the internal structure of the cell. It also ensures that there is enough time for the liquid to be transferred to the innermost pores of the cell, achieving uniform wetting of the whole, rather than just surface wetting.

[0084] In some embodiments, the wavelength of ultraviolet light is 320nm to 395nm. Specifically, the wavelength of ultraviolet light can be any value from 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, and 395nm, or any value from a range of any two values.

[0085] In some embodiments, during the ultraviolet (UV) irradiation polymerization step, the incident direction of the UV light is parallel to the thickness direction of the cell assembly; the housing has two surfaces arranged opposite each other along the thickness direction of the cell assembly, and the UV light irradiates the two surfaces respectively. Specifically, when the positive electrode, separator, and negative electrode are stacked to form the cell assembly, the thickness direction of the cell assembly is the stacking direction of the positive electrode, separator, and negative electrode; when the positive electrode, separator, and negative electrode are wound to form the cell assembly, the cross-sectional shape of the cell assembly is elliptical, and the thickness direction of the cell assembly is the minor axis direction of the ellipse. Irradiating the two surfaces of the housing arranged opposite each other along the thickness direction of the cell assembly with UV light enables the energy of the UV light to be uniformly distributed throughout the entire thickness direction of the cell, thereby ensuring that the precursor solution in contact with the electrode-electrolyte interface receives sufficient light regardless of which side it is close to, thus simultaneously completing the polymerization reaction.

[0086] Furthermore, in-situ polymerization reactions are usually accompanied by volume shrinkage. Bilateral synchronous irradiation can make the in-situ polymerization reaction and shrinkage more synchronized and uniform throughout the thickness direction, thereby greatly reducing the overall internal stress and obtaining a smoother and stronger interface layer. Bilateral irradiation can significantly shorten the total illumination time required to achieve complete curing and ensure the uniformity of curing inside the cell.

[0087] In some embodiments, at 100mW / cm 2 ~150mW / cm 2 In the step of irradiating the battery cell with ultraviolet light, the incident direction of the ultraviolet light is parallel to the thickness direction of the battery cell assembly. The ultraviolet light irradiates two surfaces of the casing that are positioned opposite each other along the thickness direction of the battery cell assembly, and the incident direction of the ultraviolet light is perpendicular to the plane of the irradiated surface. This irradiation method, in which the incident direction of the ultraviolet light is perpendicular to the plane of the irradiated surface, ensures that the energy of the ultraviolet light is uniformly distributed along the entire thickness direction of the battery cell. This ensures that the precursor solution in contact with the electrode-electrolyte interface receives sufficient light regardless of which side it is close to, thereby simultaneously completing the polymerization reaction.

[0088] In some embodiments, at 10mW / cm 2 ~30mW / cm 2 In the step of irradiating the battery cell with ultraviolet light, ultraviolet light is irradiated on two surfaces of the casing that are positioned opposite each other along the thickness direction of the battery cell assembly. The incident direction of the ultraviolet light is perpendicular to the plane of the irradiated surface. This ensures that the energy of the ultraviolet light is uniformly distributed along the entire thickness direction of the battery cell, thereby ensuring that the precursor solution in contact with the electrode-electrolyte interface receives sufficient light regardless of which side it is near, thus completing the polymerization reaction simultaneously. Furthermore, it allows the interface regions where the polymerization degree is weak due to electrode obstruction during the in-situ polymerization reaction to fully complete polymerization, reducing internal stress and achieving interface integration.

[0089] In some embodiments, at 10mW / cm 2 ~30mW / cm 2 In the step of irradiating the battery cell with ultraviolet light, the ultraviolet light is irradiated on two surfaces of the casing that are positioned opposite each other along the thickness direction of the battery cell assembly. The angle between the incident direction of the ultraviolet light and the plane of the irradiated surface is 15° to 45°. This irradiation method, with an angle of 15° to 45° between the incident direction of the ultraviolet light and the plane of the irradiated surface, allows the ultraviolet light to irradiate the precursor solution in the area blocked by the electrodes. This enables the interfacial areas where the polymerization degree is weak due to electrode blocking to fully complete polymerization, reduce internal stress, and achieve interfacial integration.

[0090] The solid-state battery prepared by the method provided in this application is used to provide electrical energy required for the operation of electrical devices. These electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0091] The preparation method of the solid electrolyte provided in this application is described below with reference to specific embodiments:

[0092] Example 1

[0093] S100, cell assembly

[0094] S101. Stack the positive electrode sheet, polypropylene / polyethylene / polypropylene separator, and graphite negative electrode sheet to form a multilayer battery cell assembly. Place the battery cell assembly into an aluminum-plastic film housing and vacuum dry at 105°C for 24 hours. The positive electrode active material in the positive electrode sheet is LiNi. 0.8 Co 0.1 Mn 0.1 O2.

[0095] S102. In an argon glove box, mix 72g pentaerythritol tetraacrylate, 22g lithium difluorosulfonyl imide, 2g photoinitiator 819, 2g fluoroethylene carbonate and 2g alumina nanoparticles, and mechanically stir for 24 hours until completely dissolved and clear to obtain a precursor solution. Inject the precursor solution into the aluminum-plastic film shell. After injection, seal and place in a container with 0.5MPa argon pressure for 4 hours to allow the precursor solution to wet the battery cell assembly.

[0096] S200, UV light polymerization

[0097] The battery cell assembled in step S100 is placed in an ultraviolet light chamber, first at a wavelength of 365nm and a light intensity of 120mW / cm. 2 The light intensity was adjusted to irradiate two surfaces of the aluminum-plastic film casing that were positioned opposite each other along the thickness direction of the battery cell assembly. Each surface was irradiated for 80 seconds, and then the intensity was switched to 20mW / cm². 2 The light intensity is simultaneously irradiated on two surfaces, with each surface irradiated for 10 minutes, forming a solid electrolyte membrane in the aluminum-plastic film shell.

[0098] S300, Post-processing

[0099] The solid-state battery is obtained by hot pressing at 70℃ and 0.5MPa for 30 seconds, followed by standard processes such as formation, aging, and capacity testing.

[0100] Examples 2-13

[0101] The preparation methods of the solid-state batteries in Examples 2-13 are the same as those in Example 1. Please refer to Table 1 for the adjustments, which will not be described in detail here.

[0102] Comparative Example 1

[0103] The solid-state battery preparation method is the same as in Example 1, but in step S102, a traditional liquid electrolyte is used instead of the precursor solution. The liquid electrolyte includes 1M lithium hexafluorophosphate and ethylene carbonate / dimethyl carbonate. After the liquid electrolyte is injected, it is not placed in a container with an argon pressure of 0.5MPa, and ultraviolet light polymerization is not carried out.

[0104] Comparative Example 2

[0105] The solid-state battery was prepared according to Example 1, but in step S200, only 100 mW / cm² was used. 2 The light intensity is used to irradiate two surfaces of the aluminum-plastic film shell that are positioned opposite each other along the thickness direction of the battery cell assembly. Each surface is irradiated for 5 minutes to complete the ultraviolet irradiation.

[0106] Comparative Example 3

[0107] The solid-state battery is prepared according to Example 1, but in step S102, after injection, it is placed under normal pressure for 4 hours.

[0108] The initial interface impedance, capacity retention after 300 cycles at 0.5C, and 1C / 0.5C rate performance of the solid-state batteries prepared in Examples 1-13 and Comparative Examples 1-3 were tested respectively. The test results are shown in Table 2.

[0109] Methods for testing initial interface impedance:

[0110] The initial interfacial impedance was tested using the AC impedance method. After the solid-state batteries prepared in Examples 1-13 and Comparative Examples 1-3 were formed, they were placed in a constant temperature environment at 25±2℃ for 2 hours at 50% SOC. An electrochemical workstation was connected, with the amplitude set to 5mV~10mV and the frequency range to 100kHz~0.1Hz.

[0111] The ohmic impedance is calculated using the intercept of the semicircle in the high-frequency region of the Nyquist plot with the real axis; the interface impedance is calculated using the diameter of the semicircle. The result is the product of the interface impedance and the electrode area, in Ω*cm. 2 The initial interface impedance is obtained.

[0112] Test method for capacity retention after 300 cycles at 0.5C:

[0113] Step 1: Use constant current and constant voltage charge-discharge cycle test. At 25±2℃, charge at 1C constant current to 4.2V, then switch to 4.2V constant voltage charge until the current is ≤0.05C.

[0114] Step 2: Let it stand for 10 minutes.

[0115] Step 3: Discharge at a constant current of 0.5C to 2.8V and record the initial discharge capacity (C1).

[0116] Step 4: Repeat steps 1-3 for 300 cycles, and record the discharge capacity (C300) on the 300th cycle.

[0117] Capacity retention rate = (C300 / C1)*100%.

[0118] Test method for 1C / 0.5C rate performance:

[0119] The following steps were taken to test the capacity ratio using different discharge rates:

[0120] Standard discharge: At 25±2℃, discharge at a constant current of 0.5C to 2.8V, and record the capacitance (C). 0.5C ).

[0121] Rate discharge: After resting, discharge at a constant current of 1C to 2.8V, and record the capacity (C). 1C ).

[0122] Calculation result: 1C / 0.5C rate performance = (C 1C / C 0.5C ) *100%.

[0123] Table 1

[0124]

[0125]

[0126]

[0127] Table 2

[0128]

[0129] Referring to Examples 1-3, in the solid-state battery preparation methods provided in Examples 1 and 2, the polymerizable monomer in the precursor solution includes only one type. The initial interfacial impedance, capacity retention after 300 cycles at 0.5C, and 1C / 0.5C rate performance of the solid-state batteries prepared by these two methods are quite similar. Example 3 uses two polymerizable monomers (pentaerythritol tetraacrylate + trimethylolpropane triacrylate), and the mass ratio of pentaerythritol tetraacrylate to trimethylolpropane triacrylate is 2.3:1, which falls within the range of (1.5~4:1). This results in the solid-state battery prepared in Example 3 having a higher initial interfacial impedance than that of Examples 1 and 2, but its capacity retention after 300 cycles at 0.5C and 1C / 0.5C rate performance are relatively lower compared to the solid-state batteries prepared in Examples 1 and 2.

[0130] In contrast, Comparative Example 1 used a traditional liquid electrolyte. After the electrolyte was injected, no pressure wetting or ultraviolet irradiation was applied. As a result, the initial interfacial impedance of the solid-state battery prepared in Comparative Example 1 was significantly higher than that of the solid-state batteries prepared in Examples 1-3. The capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance were significantly lower than those of the solid-state batteries prepared in Examples 1-3.

[0131] In the preparation method provided in Example 4, lithium bisfluorosulfonylimide was selected as the lithium salt in the precursor solution, which made the initial interface impedance of the solid-state battery prepared in Example 4 higher than that in Examples 1-3. However, the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance were relatively lower than those of the solid-state batteries prepared in Examples 1-3.

[0132] In the preparation method provided in Example 5, the photoinitiator in the precursor solution is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, and the lithium salt is the same as that in Example 4, which makes the initial interface impedance of the solid-state battery prepared in Example 5 lower than that in Example 4, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are higher than those of the solid-state battery prepared in Example 4.

[0133] In the preparation method provided in Example 6, the filler in the precursor solution is lithium lanthanum zirconium oxide, the photoinitiator is the same as in Example 5 phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, and the lithium salt is the same as in Example 4 lithium bisfluorosulfonylimide. This makes the initial interfacial impedance of the solid-state battery prepared in Example 6 lower than that in Examples 4-5, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are higher than those of the solid-state batteries prepared in Examples 4-5.

[0134] In the preparation method provided in Example 7, the interfacial stabilizer in the precursor solution is vinylene carbonate, the filler is the same lithium lanthanum zirconium oxide as in Example 6, the photoinitiator is the same phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide as in Example 5, and the lithium salt is the same lithium bisfluorosulfonylimide as in Example 4. This results in the solid-state battery prepared in Example 7 having an initial interfacial impedance higher than that of Example 6 but lower than that of Examples 4-5. The capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are not significantly different from those of the solid-state batteries prepared in Examples 4-6.

[0135] In the preparation method provided in Example 8, after the precursor solution is injected, the wetting pressure in Example 8 is lower than that in Example 1, and the wetting time is longer than that in Example 1. As a result, the initial interface impedance of the solid-state battery prepared in Example 8 is higher than that in Example 1, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are lower than those in Example 1.

[0136] The wetting pressure in Example 9 was higher than that in Example 1, and the wetting time was shorter than that in Example 1. As a result, the initial interface impedance of the solid-state battery prepared in Example 9 was lower than that in Example 1, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance were higher than those in Example 1.

[0137] In contrast, in Comparative Example 3, the preparation method involved placing the solid-state battery under normal pressure for 4 hours after the precursor solution was injected, resulting in an initial interfacial impedance as high as 92.5 Ω·cm. 2 The performance was significantly higher than that of Example 1, but the capacity retention rate after 300 cycles at 0.5C and the rate performance at 1C / 0.5C were significantly lower than those of Example 1.

[0138] In the preparation method provided in Example 10, the light intensity of the first stage of ultraviolet irradiation is lower than that in Example 1, and the irradiation time is longer than that in Example 1. As a result, the initial interface impedance of the solid-state battery prepared in Example 10 is higher than that in Example 1, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are lower than those in Example 1.

[0139] In the preparation method provided in Example 11, the light intensity of the first stage of ultraviolet irradiation is higher than that in Example 1, and the irradiation time is shorter than that in Example 1. As a result, the initial interface impedance of the solid-state battery prepared in Example 11 is lower than that in Example 1, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are higher than those in Example 1.

[0140] In the preparation method provided in Example 12, the light intensity of the second stage of ultraviolet irradiation is lower than that in Example 1, and the irradiation time is longer than that in Example 1. As a result, the initial interface impedance of the solid-state battery prepared in Example 12 is lower than that in Example 1, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are higher than those in Example 1.

[0141] In the preparation method provided in Example 13, the light intensity of the second stage ultraviolet irradiation is higher than that in Example 1, and the irradiation time is shorter than that in Example 1. As a result, the initial interface impedance of the solid-state battery prepared in Example 13 is higher than that in Example 1, and the capacity retention rate after 300 cycles at 0.5C and the 1C / 0.5C rate performance are lower than those in Example 1.

[0142] In contrast, Comparative Example 2's preparation method only uses a light intensity of 100 mW / cm² in the first stage. 2 The UV irradiation polymerization step was terminated after 5 minutes of UV light irradiation of the casing, resulting in an initial interfacial impedance of 85.2 Ω·cm for the solid-state battery prepared in Comparative Example 2. 2 The performance was significantly higher than that of Example 1, but the capacity retention rate after 300 cycles at 0.5C and the rate performance at 1C / 0.5C were significantly lower than those of Example 1.

[0143] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of this application and do not limit the scope of protection of this patent application.

Claims

1. A method for preparing a solid-state battery, characterized in that, include: Cell assembly: The positive electrode, separator and negative electrode are stacked or wound to form a cell assembly, and the cell assembly is placed in the housing; The precursor solution is injected into the casing to obtain the battery cell. The precursor solution, by mass percentage, is a mixture of 60wt%–80wt% polymerizable monomers, 15wt%–25wt% lithium salt, 1wt%–3wt% photoinitiator, 0wt%–5wt% filler, and 0.5wt%–2wt% interface stabilizer, with the sum of all components being 100wt%. Ultraviolet light aggregation: The cell is irradiated with ultraviolet light, causing the polymerizable monomers to undergo in-situ polymerization to form a solid electrolyte membrane.

2. The solid-state battery preparation method according to claim 1, characterized in that, The step of irradiating the battery cell with ultraviolet light includes: at 100mW / cm 2 ~150mW / cm 2 The battery cell is irradiated with ultraviolet light at a light intensity of 60s to 120s.

3. The solid-state battery preparation method according to claim 2, characterized in that, The aforementioned 100mW / cm 2 ~150mW / cm 2 Following the step of irradiating the battery cell with ultraviolet light at a light intensity of 10mW / cm², the method further includes: 2 ~30mW / cm 2 The battery cell is irradiated with ultraviolet light at a light intensity of 5 to 15 minutes.

4. The solid-state battery preparation method according to claim 1, characterized in that, The polymerizable monomer is selected from one or more of methyl acrylate, ethyl acrylate, tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

5. The solid-state battery preparation method according to claim 4, characterized in that, The polymerizable monomer is selected from any two of the following: methyl acrylate, ethyl acrylate, tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. The mass ratio of any two polymerizable monomers is 1:(1.5~4).

6. The solid-state battery preparation method according to claim 1, characterized in that, The lithium salt is selected from one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide.

7. The solid-state battery preparation method according to claim 1, characterized in that, The photoinitiator is selected from one or more of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

8. The solid-state battery preparation method according to claim 1, characterized in that, The filler is selected from one or more of alumina, lithium lanthanum zirconium oxide, lithium lanthanum titanate, lithium aluminum titanium phosphate, lithium nitride, and silicon dioxide.

9. The solid-state battery preparation method according to claim 1, characterized in that, The interface stabilizer is selected from one or more of vinylene carbonate, fluoroethylene carbonate, ethylene ethylene carbonate, 1,3-propane sulcolone, and lithium bis(oxalate)borate.

10. The solid-state battery preparation method according to claim 1, characterized in that, In the step of injecting the precursor solution into the housing, after injection, the solution is maintained at a pressure of 0.3MPa to 0.8MPa for 2h to 6h to allow the precursor solution to wet the cell assembly.

11. The method for preparing a solid-state battery according to any one of claims 1 to 3, characterized in that, The wavelength of the ultraviolet light is 320nm~395nm.

12. The method for preparing a solid-state battery according to any one of claims 1 to 3, characterized in that, In the ultraviolet light polymerization step, the incident direction of the ultraviolet light is parallel to the thickness direction of the battery cell assembly; The housing has two surfaces that are arranged opposite each other along the thickness direction of the battery cell assembly, and the ultraviolet light irradiates the two surfaces respectively.

13. The solid-state battery preparation method according to claim 2, characterized in that, The aforementioned 100mW / cm 2 ~150mW / cm 2 In the step of irradiating the battery cell with ultraviolet light, the incident direction of the ultraviolet light is parallel to the thickness direction of the battery cell assembly. The ultraviolet light irradiates two surfaces of the housing that are arranged opposite to each other along the thickness direction of the battery cell assembly, and the incident direction of the ultraviolet light is perpendicular to the plane of the irradiated surface.

14. The solid-state battery preparation method according to claim 3, characterized in that, The aforementioned 10mW / cm 2 ~30mW / cm 2 In the step of irradiating the battery cell with ultraviolet light, the ultraviolet light irradiates two surfaces of the housing that are arranged opposite to each other along the thickness direction of the battery cell assembly. The incident direction of the ultraviolet light is perpendicular to the plane of the surface being irradiated, or the angle between the incident direction of the ultraviolet light and the plane of the surface being irradiated is 15° to 45°.

Images