Quasi-solid-state battery and manufacturing method thereof

Abstract

The invention provides a quasi-solid-state battery and a manufacturing method thereof. The manufacturing method comprises the following steps: preparing at least one of a positive plate and a negative plate based on an ultraviolet in-situ curing method; and assembling the positive plate, the diaphragm and the negative plate to obtain the dry battery cell. And injecting a fluorine-containing ionic liquid electrolyte into the dry cell, and infiltrating the dry cell with the fluorine-containing ionic liquid to form an organic-inorganic composite interfacial film. According to the manufacturing method, the electrode precursor can be rapidly cured to obtain the electrode plate without baking, and the manufacturing efficiency is improved. Moreover, the volume change in the battery cell circulation process can be relieved, and the safety performance of the battery cell is improved. The quasi-solid-state battery has high safety performance and is suitable for large-scale production.

Description

Technical Field

[0001] This application belongs to the technical field of lithium-ion batteries and relates to a quasi-solid-state battery and a method for manufacturing the same. Background Art

[0002] Currently, mainstream lithium batteries rely on liquid electrolytes (e.g., LiPF6 / carbonate system), which are technologically mature, inexpensive, and have high ionic conductivity. However, their organic solvents have high volatility and flammability. When there is an internal short circuit, overcharge, high temperature, or mechanical damage in the battery, it is easy to cause electrolyte leakage, trigger thermal runaway, and lead to fire or even explosion (such as accidents of electric vehicle power battery packs), with very serious consequences.

[0003] To address the safety hazards of liquid batteries, a technical solution using solid electrolytes (such as oxide LLZO, sulfide LGPS, or polymer PEO) to replace the liquid electrolyte system has been proposed. Solid-state batteries have advantages such as high safety and high energy density potential due to the use of solid electrolytes, but they have multiple technical obstacles. For example, the ionic conductivity of solid electrolytes is relatively low, and the fast charging ability and power density are limited; the solid-solid interface contact is insufficient, and a high-impedance layer is easily formed between the electrode and the electrolyte, resulting in cyclic capacity attenuation; moreover, it is difficult to form a film for solid electrolytes, the raw materials and the integrated cost of the electrode-electrolyte are high, and the volume expansion of the electrode during charge and discharge causes interface peeling, affecting the structural stability, etc. As a result, solid-state batteries are still in the research and development stage and have not yet achieved large-scale mass production. Quasi-solid-state batteries are between liquid batteries and solid-state batteries, that is, they have the high safety advantages of solid-state batteries and at the same time use liquid electrolytes or gel electrolytes to improve ionic conductivity and reduce interface resistance, which is a potential transitional technical solution.

[0004] Therefore, how to provide a quasi-solid-state battery and a method for manufacturing the same to meet the market demand for lithium batteries with high safety performance has become an important technical problem that needs to be solved urgently by those skilled in the art.

[0005] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solutions of this application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of this application. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the purpose of this application is to provide a quasi-solid-state battery and a method for manufacturing the same, aiming to solve the problem of meeting the market demand for lithium batteries with high safety performance.

[0007] To achieve the above object and other related objects, in a first aspect, the present application provides a method for manufacturing a quasi-solid-state battery, comprising the following steps:

[0008] Preparing at least one of a positive electrode sheet and a negative electrode sheet based on an ultraviolet in-situ curing method;

[0009] Assembling the positive electrode sheet, the separator, and the negative electrode sheet to obtain a dry battery cell;

[0010] Injecting a fluorine-containing ionic liquid electrolyte into the dry battery cell, and the fluorine-containing ionic liquid infiltrates the dry battery cell and forms an organic-inorganic composite interface film.

[0011] In an optional embodiment, the ultraviolet in-situ curing method includes:

[0012] Obtaining an active material, a polymer monomer, and a polymer initiator and mixing them to obtain an electrode material;

[0013] Pressing and laminating the electrode material to obtain an electrode precursor;

[0014] Performing ultraviolet in-situ curing on the electrode precursor to obtain the positive electrode sheet and / or the negative electrode sheet, and the polymer monomer forms a polymer component after the ultraviolet in-situ curing.

[0015] In an optional embodiment, preparing a positive electrode sheet based on an ultraviolet in-situ curing method includes the steps of obtaining a positive electrode active material, a positive electrode polymer monomer, and a positive electrode polymer initiator; wherein,

[0016] The positive electrode active material includes at least one of lithium iron phosphate, nickel cobalt manganese ternary material, lithium manganese iron phosphate, and lithium manganate; and / or,

[0017] The positive electrode polymer monomer includes at least one of dipropylene glycol diacrylate and trimethylolpropane triacrylate; and / or,

[0018] The positive electrode polymer initiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and thioxanthone initiators.

[0019] In an optional embodiment, preparing a negative electrode sheet based on an ultraviolet in-situ curing method includes the steps of obtaining a negative electrode active material, a negative electrode polymer monomer, and a negative electrode polymer initiator; wherein,

[0020] The negative electrode active material includes at least one of graphite materials, silicon-based materials, and tin-based materials; and / or,

[0021] The negative electrode polymer monomer includes at least one of 1,6-hexanediol diacrylate and ethoxylated bisphenol A diacrylate; and / or,

[0022] The negative electrode polymer initiator includes at least one of 2-hydroxy-2-methylpropiophenone and 1-hydroxycyclohexyl phenyl ketone.

[0023] In an alternative embodiment, the electrode precursor is subjected to ultraviolet in-situ curing by ultraviolet light irradiation under preset conditions, and the preset conditions include at least one of the following conditions:

[0024] The wavelength range of the ultraviolet light is 10 nm - 400 nm;

[0025] The intensity range of the ultraviolet light is 200 mW / cm 2 - 700 mW / cm 2 ;

[0026] The irradiation time range of the ultraviolet light is 10 s - 180 s.

[0027] In an alternative embodiment, by mass percentage, in the electrode material:

[0028] The proportion range of the active material is 70% - 98%; and / or,

[0029] The proportion range of the polymer monomer is 1% - 5%; and / or,

[0030] The proportion range of the polymer initiator is 0.1% - 3%.

[0031] In an alternative embodiment, the electrode material further includes at least one of a conductive agent and a binder; wherein,

[0032] The conductive agent includes at least one of carbon nanotubes, graphene, and conductive carbon black; and / or,

[0033] The proportion of the conductive agent is 0.01% - 5%; and / or,

[0034] The binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, and carboxymethyl cellulose; and / or,

[0035] The proportion of the binder is 0.1% - 5%.

[0036] In an alternative embodiment, the fluorine-containing ionic liquid electrolyte includes a fluorine-containing ionic liquid and a lithium salt, the fluorine-containing ionic liquid includes 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide salt, and the lithium salt includes lithium bis(trifluoromethanesulfonyl)imide.

[0037] In an alternative embodiment, the injection volume coefficient range of injecting the fluorine-containing ionic liquid electrolyte into the dry battery cell is 0.1 g / Ah - 1.5 g / Ah; the concentration range of the lithium salt is 0.1 mol / L - 5 mol / L.

[0038] In a second aspect, the present application also provides a quasi-solid-state battery, which includes a dry battery cell and a fluorine-containing ionic liquid electrolyte. The dry battery cell includes a positive electrode sheet, a separator, and a negative electrode sheet. Among them, at least one of the positive electrode sheet and the negative electrode sheet is prepared based on an ultraviolet in-situ curing method, and the fluorine-containing ionic liquid is configured to infiltrate the dry battery cell and form an organic-inorganic composite interface film.

[0039] As described above, in the manufacturing method of the quasi-solid-state battery of the present application, the positive electrode sheet / negative electrode sheet is formed based on the ultraviolet in-situ curing method, which can realize the low-temperature and rapid curing of the electrode sheet without baking, and improve the manufacturing efficiency of the electrode sheet and the battery. Moreover, based on the synergistic effect of the polymer components generated in the ultraviolet in-situ curing method and the fluorine-containing ionic liquid in the fluorine-containing ionic liquid electrolyte, an organic-inorganic composite interface film with high ionic conductivity, mechanical strength, and flexibility is formed to relieve the volume change during the cycling of the battery cell while ensuring the basic performance of the battery (such as capacity and cycle life), and improve the overall safety performance of the battery cell. In addition, a customized polymer monomer / polymer initiator combination and ratio are designed for the positive electrode sheet and the negative electrode sheet to match the electrochemical environment characteristics of the positive electrode sheet and the negative electrode sheet, further improving the working performance and safety performance of the battery while ensuring the mechanical strength and reliability of the electrode sheet. The quasi-solid-state battery of the present application has high safety performance, and its overall structure is simple and easy to implement, suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It shows a flowchart of the steps of the manufacturing method of the quasi-solid-state battery provided by the embodiment of the present application.

[0041] Figure 2 It shows a graph of the change data of the swelling force of the battery cell with the number of cycles in Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following specifically illustrates the embodiments of the present application through specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0043] Please refer to Figures 1 to 2 . It should be noted that the drawings provided in this embodiment only illustrate the basic concept of the present application in a schematic manner. Therefore, only the components related to the present application are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0044] An embodiment of the present application provides a method for manufacturing a quasi-solid-state battery. Please refer to Figure 1 , Figure 1 which shows a flowchart of the steps of this manufacturing method. The manufacturing method includes the following steps:

[0045] S1: Prepare at least one of the positive electrode sheet and the negative electrode sheet based on the ultraviolet in-situ curing method;

[0046] S2: Assemble the positive electrode sheet, the separator, and the negative electrode sheet to obtain a dry battery cell;

[0047] S3: Inject a fluorine-containing ionic liquid electrolyte into the dry battery cell. The fluorine-containing ionic liquid infiltrates the dry battery cell and forms an organic-inorganic composite interface film.

[0048] First, perform step S1 to prepare at least one of the positive electrode sheet and the negative electrode sheet based on the ultraviolet in-situ curing method.

[0049] In some embodiments, the ultraviolet in-situ curing method includes: obtaining an active material, a polymer monomer, and a polymer initiator and mixing them to obtain an electrode material; pressing and laminating the electrode material to obtain an electrode precursor; performing ultraviolet in-situ curing on the electrode precursor to obtain the positive electrode sheet and / or the negative electrode sheet. The polymer monomer forms a polymer component after the ultraviolet in-situ curing. To avoid ambiguity, "at least one" as described in this article means "one or more", and "at least one kind" means "one kind or more kinds".

[0050] In the embodiment of the present application, preparing at least one of the positive electrode sheet and the negative electrode sheet based on the ultraviolet in-situ curing method includes the following three situations: preparing the positive electrode sheet based on the ultraviolet in-situ curing method and preparing the negative electrode sheet based on a traditional method (for example, the wet coating and baking method); or, preparing the positive electrode sheet based on a traditional method and preparing the negative electrode sheet based on the ultraviolet in-situ curing method; or, preparing the positive electrode sheet based on the ultraviolet in-situ curing method and preparing the negative electrode sheet based on the ultraviolet in-situ curing method.

[0051] In some embodiments, the electrode precursor is subjected to ultraviolet in-situ curing by ultraviolet light irradiation under preset conditions. The preset conditions include at least one of the following conditions: the wavelength range of the ultraviolet light is 10 nm - 400 nm. For example, the wavelength range of the ultraviolet light can be 10 nm, 100 nm, 250 nm, 300 nm, 350 nm, or 400 nm. The intensity range of the ultraviolet light is 200 mW / cm 2 -700 mW / cm 2 , for example, the intensity of the ultraviolet light can be 200 mW / cm 2 , 300 mW / cm 2 , 400 mW / cm 2, 500 mW / cm 2 , 600 mW / cm 2 or 700 mW / cm 2 . The irradiation time range of the ultraviolet light is 10 s - 180 s. For example, the irradiation time of the ultraviolet light can be 10 s, 30 s, 60 s, 90 s, 120 s, 150 s or 180 s. The preset conditions are designed after comprehensive consideration in terms of the structural parameters of the electrode sheet, the material types of the polymer monomers and polymer initiators included in the electrode sheet, the performance parameters of the electrode sheet, etc.

[0052] In the embodiments of the present application, by means of ultraviolet in-situ curing of the electrode sheet (positive electrode sheet and / or negative electrode sheet), combined with the process conditions of in-situ curing, the electrode sheet can be prepared under the condition of no baking, and after assembling the dry battery cell, the electrolyte can be directly injected without baking. On the one hand, during the ultraviolet in-situ curing process, the polymer initiator in the electrode precursor absorbs ultraviolet light energy and decomposes to generate active substances (for example, free radicals). The generation of active substances triggers the rapid polymerization reaction of polymer monomers to form a three-dimensional network structure, so as to ensure the structural integrity of the electrode, and it can avoid the traditional electrode sheet that needs to go through a baking process to volatilize and remove the solvent, relying on a high-temperature environment and taking too much time (for example, 12 - 24 h). And, by controlling the process conditions of ultraviolet in-situ curing (for example, precise regulation of the wavelength), synchronous curing from the surface layer to the inside of the electrode precursor can be achieved, and stress cracking or interface delamination caused by uneven curing can be avoided. Especially for thick electrode sheets, multi-band ultraviolet light sources can be designed for staged curing to meet the requirements of uniform and sufficient curing of thick electrode sheets. On the other hand, the cross-linked network structure of the polymer components formed after the reaction of polymer monomers is dense, and the hygroscopicity is significantly reduced. After assembling into a dry battery cell, there is no need for vacuum baking to remove moisture, and the electrolyte can be directly injected. In a specific example, the ultraviolet in-situ curing is carried out in an inert atmosphere to avoid the adverse effects of oxygen in the air on free radicals, thereby improving the curing efficiency. For example, the inert atmosphere can be an N2 atmosphere.

[0053] In some embodiments, the ratio range between the proportion of the polymer initiator and the proportion of the polymer monomer is 0.02:1 to 3:1 by mass percentage. For example, the ratio between the proportion of the polymer initiator and the proportion of the polymer monomer can be 0.02:1, 0.1:1, 0.5:1, 1:1, 2:1, or 3:1. Among them, there is a direct synergistic effect between the proportion of the polymer monomer and the proportion of the polymer initiator. If the proportion of the polymer initiator is too small (for example, less than 2% of the proportion of the polymer monomer), insufficient active substances can be generated under ultraviolet light irradiation to trigger the polymerization reaction of the polymer monomer, resulting in incomplete reaction of the polymer monomer and remaining in the electrode sheet. In addition to affecting the curing effect and causing insufficient mechanical strength of the electrode sheet, leading to the shedding of active materials and cracking of the electrode sheet, it will also affect the performance and reliability of the battery. For example, the remaining unreacted polymer monomer will decompose during the charge and discharge process of the battery to produce decomposition products, affecting the charge and discharge performance of the battery. If the proportion of the polymer initiator is too large (for example, more than 3 times the proportion of the polymer monomer), some unnecessary side reactions may occur due to the presence of unreacted polymer initiator. For example, it may consume and waste some polymer monomers, or react with other components in the battery, or cause the polymer monomer to form an overly dense network structure after polymerization, affecting ion conduction.

[0054] In some embodiments, by mass percentage, in the electrode material: the proportion of the active material ranges from 70% to 98%. For example, the proportion of the active material can be 70%, 75%, 80%, 85%, 90% or 98%. And / or, the proportion of the polymer monomer ranges from 1% to 5%. For example, the proportion of the polymer monomer ranges from 1%, 1.5%, 2%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% or 5%. And / or, the proportion of the polymer initiator ranges from 0.1% to 3%. For example, the proportion of the polymer initiator ranges from 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5% or 3%. Among them, if the proportion of the polymer monomer is too high, it may lead to a decrease in the proportion of the active material, directly affecting the battery capacity. Moreover, the polymer layer formed subsequently is relatively thick, which may affect the infiltration degree of the electrolyte and hinder the migration of lithium ions, thus affecting the performance of the battery such as the rate performance. In addition, if the proportion of the polymer monomer is too high and not fully reacted, the unreacted polymer monomer may undergo thermal decomposition during subsequent use, exacerbating the risk of thermal runaway. If the proportion of the polymer monomer is relatively small, it may lead to a relatively loose cross-linked network structure, reducing the binding degree of the active material, making the active material prone to falling off during charge and discharge, thus shortening the cycle life of the battery. At the same time, it will also cause insufficient mechanical strength of the electrode sheet, leading to potential safety hazards. Among them, "proportion" refers to the ratio of the mass of this material to the sum of the masses of all materials in the entire electrode precursor. Therefore, the proportion of the active material, the proportion of the polymer monomer and the proportion of the polymer initiator are designed based on the actual needs of the battery.

[0055] In some embodiments, the electrode material further includes at least one of a conductive agent and a binder. Among them, the proportion of the conductive agent is 0.01% - 5%. For example, the proportion of the conductive agent can be 0.01%, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0% or 5%. The proportion of the binder is 0.1% - 5%. For example, the proportion of the binder can be 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0% or 5%. For example, the positive electrode precursor includes a positive electrode conductive agent and / or a positive electrode binder, and the negative electrode precursor includes a negative electrode conductive agent and / or a negative electrode binder. The positive electrode conductive agent in the positive electrode material and the negative electrode conductive agent in the negative electrode material can be the same or different. Similarly, the positive electrode binder in the positive electrode material and the negative electrode binder in the negative electrode material can be the same or different.

[0056] In some embodiments, the conductive agent includes at least one of carbon nanotubes, graphene, and conductive carbon black, and the binder includes at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC). For example, the positive electrode conductive agent in the positive electrode material and the negative electrode conductive agent in the negative electrode material may be the same or different. For example, the positive electrode conductive agent may be carbon nanotubes, and the negative electrode conductive agent may be conductive carbon black. Further, for example, the positive electrode binder may be polyvinylidene fluoride, and the negative electrode binder may be a mixed binder of styrene-butadiene rubber and carboxymethyl cellulose.

[0057] In some embodiments, preparing a positive electrode sheet based on an ultraviolet in-situ curing method includes the steps of obtaining a positive electrode active material, a positive electrode polymer monomer, and a positive electrode polymer initiator. Further, the following steps are also included: mixing the obtained positive electrode active material, positive electrode polymer monomer, and positive electrode polymer initiator to obtain a positive electrode material; pressing and laminating the positive electrode material to obtain a positive electrode precursor; and subjecting the positive electrode precursor to ultraviolet in-situ curing to obtain the positive electrode sheet.

[0058] Further, the positive electrode active material includes at least one of lithium iron phosphate, nickel cobalt manganese ternary material, lithium manganese iron phosphate, and lithium manganate. And / or, the positive electrode polymer monomer includes at least one of dipropylene glycol diacrylate (TPGDA) and trimethylolpropane triacrylate (TMPTA); and / or, the positive electrode polymer initiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) and thioxanthone initiator (Omnipol TX).

[0059] In a specific example, obtaining a positive electrode active material, a positive electrode polymer monomer, and a positive electrode polymer initiator and mixing them to obtain a positive electrode material includes the following steps: obtaining a positive electrode active material, a positive electrode polymer monomer, a positive electrode polymer initiator, a positive electrode conductive agent, and a positive electrode binder based on a first preset ratio. Stir the positive electrode active material, positive electrode polymer monomer, positive electrode polymer initiator, and positive electrode conductive agent, and mix them evenly to obtain a positive electrode premix. Add the positive electrode binder to the positive electrode premix and perform shear mixing to obtain the positive electrode material.

[0060] In a specific example, pressing and laminating the positive electrode material to obtain a positive electrode precursor includes the following steps: providing a positive electrode current collector (for example, aluminum foil). Transferring the positive electrode material onto the positive electrode current collector. Pressing the positive electrode current collector with the transferred positive electrode material, so that the positive electrode materials are closely arranged and laminated on the positive electrode current collector to obtain a positive electrode precursor, which includes a current collector and a positive electrode material film covering the current collector. For example, the pressing method can be multi-roll transfer pressing. In another specific example, the positive electrode material can be pressed into a positive electrode material film first, and then the positive electrode material film is transferred onto the positive electrode current collector, and the positive electrode material film is closely laminated with the positive electrode current collector.

[0061] In some embodiments, preparing a negative electrode sheet based on the ultraviolet in-situ curing method includes the steps of obtaining a negative electrode active material, a negative electrode polymer monomer, and a negative electrode polymer initiator. Further, the following steps are also included: mixing the obtained negative electrode active material, negative electrode polymer monomer, and negative electrode polymer initiator to obtain a negative electrode material; pressing and laminating the negative electrode material to obtain a negative electrode precursor; and subjecting the negative electrode precursor to ultraviolet in-situ curing to obtain the negative electrode sheet.

[0062] Further, the negative electrode active material includes at least one of a graphite material, a silicon-based material, and a tin-based material. And / or, the negative electrode polymer monomer includes at least one of 1,6-hexanediol diacrylate (HDDA) and ethoxylated bisphenol A diacrylate (EO-BPADA). And / or, the negative electrode polymer initiator includes at least one of 2-hydroxy-2-methylpropiophenone and 1-hydroxycyclohexyl phenyl ketone.

[0063] In a specific example, obtaining a negative electrode active material, a negative electrode polymer monomer, and a negative electrode polymer initiator and mixing them to obtain a negative electrode material includes the following steps: obtaining a negative electrode active material, a negative electrode polymer monomer, a negative electrode polymer initiator, a negative electrode conductive agent, and a negative electrode binder based on a second preset ratio. Stirring the negative electrode active material, negative electrode polymer monomer, negative electrode polymer initiator, and negative electrode conductive agent, and mixing them evenly to obtain a negative electrode premix. Adding the negative electrode binder to the negative electrode premix and performing shear mixing to obtain the negative electrode material. The second preset ratio and the foregoing first preset ratio are both set based on the actual performance requirements of the battery.

[0064] In a specific example, pressing and laminating the negative electrode material to obtain a negative electrode precursor includes the following steps: providing a negative electrode current collector (e.g., a copper foil). Transferring the negative electrode material onto the negative electrode current collector. Pressing the negative electrode current collector with the transferred negative electrode material thereon such that the negative electrode material is closely arranged and laminated on the negative electrode current collector to obtain a negative electrode precursor, which includes a negative electrode current collector and a negative electrode material film covering the negative electrode current collector. For example, the pressing method can be multi-roll transfer pressing. In another specific example, the negative electrode material can be pressed into a negative electrode material film first, and then the negative electrode material film is transferred onto the negative electrode current collector and the negative electrode material film is closely laminated with the negative electrode current collector.

[0065] In some embodiments, the thickness range of the positive electrode sheet is 50 μm to 500 μm. For example, the thickness of the positive electrode sheet can be 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, or 500 μm. The thickness range of the negative electrode sheet is 50 μm to 400 μm. For example, the thickness of the positive electrode sheet can be 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, or 400 μm.

[0066] Since the positive electrode sheet is in an oxidizing environment inside the battery, the positive electrode polymer monomer and the positive electrode polymer initiator provided in the embodiments of the present application are adapted to each other to ensure that the individuals (positive electrode polymer monomer, positive electrode polymer initiator) and the generated polymer components have high antioxidant properties to prevent the initiator, polymer, and polymer from decomposing at high potentials, thereby maintaining the working performance and reliability of the battery. At the same time, the thickness selection of the positive electrode sheet also needs to be considered to avoid the situation where the inside of the positive electrode sheet is not fully cured when the positive electrode sheet is relatively thick, thereby avoiding the adverse effects caused by the residue of unreacted positive electrode polymer monomers. For example, trimethylbenzoyl-diphenylphosphine oxide responds to long-wavelength ultraviolet light (e.g., 380 nm), and the long-wavelength ultraviolet light has strong penetrability, which can ensure the deep curing of the positive electrode sheet. The polymer component obtained after the above positive electrode polymer monomer undergoes a polymerization reaction has a high crosslinking density and can form a rigid network to avoid the situation where stress concentration is easily generated during charge and discharge and particle shedding occurs when the hardness of the positive electrode active material is relatively high. Moreover, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide has certain chemical inertness, a relatively stable structure, and is not likely to undergo catalytic side reactions with transition metals (e.g., Ni, Co) that the positive electrode active material may include (transition metals may catalyze the decomposition of the polymer initiator or undergo a coordination reaction with the polymer monomer).

[0067] Since the negative electrode sheet is in a reducing environment inside the battery, the negative electrode polymer monomer and the negative electrode polymer initiator provided in the embodiments of the present application are adapted to each other. On the premise of ensuring that the individual (negative electrode polymer monomer, negative electrode polymer initiator) and the generated polymer components have anti-reducibility, they also have good flexibility. In addition to avoiding subsequent reactions, they also need to withstand the expansion effect of the negative electrode material during lithium insertion / extraction.

[0068] Then, step S2 is executed to assemble the positive electrode sheet, the separator and the negative electrode sheet to obtain a dry battery cell.

[0069] In some embodiments, the method of assembling the positive electrode sheet, the separator and the negative electrode sheet to obtain a dry battery cell includes at least one of winding and laminating. Among them, the separator is located between adjacent positive electrode sheets and negative electrode sheets, and the separator can be a PE-based film.

[0070] After that, step S3 is executed to inject a fluorine-containing ionic liquid electrolyte into the dry battery cell, and the fluorine-containing ionic liquid infiltrates the dry battery cell and forms an organic-inorganic composite interface film.

[0071] In the embodiments of the present application, after the fluorine-containing ionic liquid electrolyte is injected into the dry battery cell, the fluorine-containing ionic liquid infiltrates the dry battery cell and acts on the polymer components in the dry battery cell to form an organic-inorganic composite interface film with ionic conductivity. Among them, when both the positive electrode sheet and the negative electrode sheet are prepared by ultraviolet in-situ curing method, the organic-inorganic composite interface film formed between the fluorine-containing ionic liquid and the interface of the negative electrode sheet is a composite SEI film, and the organic-inorganic composite interface film formed between the fluorine-containing ionic liquid and the interface of the positive electrode sheet is a composite passivation film. The formation of the organic-inorganic composite interface film helps to optimize the interface and improve the cycle performance and safety performance of the battery.

[0072] In some embodiments, the fluorine-containing ionic liquid electrolyte includes a fluorine-containing ionic liquid and a lithium salt. The fluorine-containing ionic liquid includes 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI), and the lithium salt includes lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0073] In the embodiments of the present application, after forming the electrode sheet (positive electrode sheet and / or negative electrode sheet) by ultraviolet in-situ curing method, a fluorine-containing ionic liquid is injected into the dry battery cell. Among them, the TFSI of the fluorine-containing ionic liquid -The F element in (bis(trifluoromethylsulfonyl)imide ion) forms a weak bond with the ester group in acrylate in the polymer monomer, promoting their co-deposition at the interface, thereby forming a composite interface film composed of an inorganic layer rich in LiF and an organic layer containing acrylate derivatives. Specifically, the fluorine atom of bis(trifluoromethylsulfonyl)imide ion forms a weak bond with the ester group (C=O) of acrylate through dipole-dipole interaction or hydrogen bond. The formation of the weak bond promotes the co-deposition of the ionic liquid and the resin at the electrode interface. After their co-deposition at the interface, bis(trifluoromethylsulfonyl)imide ion decomposes during the electrochemical process (for example, the formation process), releasing fluorine element, and the fluorine element combines with lithium ions to generate LiF, thereby obtaining an inorganic layer rich in LiF and an organic layer containing acrylate derivatives. Among them, the inorganic layer rich in LiF has high ionic conductivity and high mechanical strength, which can promote the migration of lithium ions and enhance the rigidity of the interface film at the same time. The organic layer endows flexibility, and the interaction between the ester group of acrylate and the F atom of TFSI- can strengthen the interface bonding between the organic and inorganic layers and improve the overall stability of the composite interface film.

[0074] In some embodiments, the injection volume coefficient range of the fluorine-containing ionic liquid electrolyte injected into the dry battery cell is 0.1 g / Ah - 1.5 g / Ah. For example, the injection volume coefficient of the fluorine-containing ionic liquid can be 0.1 g / Ah, 0.4 g / Ah, 0.8 g / Ah, 1.0 g / Ah, 1.2 g / Ah or 1.5 g / Ah. The concentration range of the lithium salt is 0.1 mol / L - 5 mol / L. For example, the concentration range of the lithium salt can be 0.1 mol / L, 0.8 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L or 5 mol / L.

[0075] In the embodiments of the present application, the injection volume coefficient of the fluorine-containing ionic liquid electrolyte is significantly lower than that of the electrolyte in traditional batteries (for example, the injection volume coefficient of ternary system batteries is 3 g / Ah - 3.5 g / Ah, and the injection volume coefficient of LFP system is 5 g / Ah). On the premise of fully wetting the internal structure of the dry battery cell (including the positive electrode sheet, negative electrode sheet and separator), the fluorine element in the fluorine-containing ionic liquid can interact with the polymer group in the dry battery cell to form a stable interface film, enhancing the interface stability, reducing the demand for the injection volume of the electrolyte, and at the same time, side reactions (such as electrolyte decomposition) caused by insufficient injection volume of the electrolyte will not occur. At the same time, the fluorine-containing ionic liquid has a wider electrochemical window and stronger antioxidant property, which can reduce the oxidation decomposition loss of the electrolyte under high voltage and can effectively maintain the battery performance at a lower injection volume.

[0076] The manufacturing method of the quasi-solid-state battery according to the embodiments of the present application forms the positive electrode sheet / negative electrode sheet based on the ultraviolet in-situ curing method, which can achieve low-temperature and rapid curing of the electrode sheet without baking, and improve the manufacturing efficiency of the electrode sheet and the battery. Moreover, based on the synergistic effect of the polymer components generated in the ultraviolet in-situ curing method and the fluorine-containing ionic liquid in the fluorine-containing ionic liquid electrolyte, an organic-inorganic composite interface film with high ionic conductivity, mechanical strength and flexibility is formed to alleviate the volume change during the cycling of the battery cell while ensuring the basic performance of the battery (such as capacity, cycle life), and improve the overall safety performance of the battery cell. In addition, a customized polymer monomer / polymer initiator combination and proportion are designed for the positive electrode sheet and the negative electrode sheet to match the electrochemical environment characteristics of the positive electrode sheet and the negative electrode sheet, further improving the working performance and safety performance of the battery while ensuring the mechanical strength and reliability of the electrode sheet.

[0077] The embodiments of the present application also provide a quasi-solid-state battery. The quasi-solid-state battery can be manufactured based on the above-mentioned manufacturing method of the quasi-solid-state battery. The quasi-solid-state battery includes a dry battery cell and a fluorine-containing ionic liquid electrolyte. The dry battery cell includes a positive electrode sheet, a separator and a negative electrode sheet (the separator is used to separate the positive electrode sheet and the negative electrode sheet). Among them, at least one of the positive electrode sheet and the negative electrode sheet is prepared by the ultraviolet in-situ curing method. The fluorine-containing ionic liquid is configured to infiltrate the dry battery cell and form an organic-inorganic composite interface film.

[0078] The quasi-solid-state battery according to the embodiments of the present application has high safety performance, and the overall structure is simple and easy to implement, suitable for large-scale production.

[0079] The following further describes the present invention in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present invention.

[0080] Embodiment 1

[0081] First, the preparation of the positive electrode sheet and the preparation of the negative electrode sheet are carried out.

[0082] The steps for preparing the positive electrode sheet are as follows:

[0083] Mix 4.75 kg of lithium iron phosphate, 100 g of conductive carbon black, 50 g of tripropylene glycol diacrylate (TPGDA) and 50 g of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) and stir evenly;

[0084] Then add 50 g of polytetrafluoroethylene and obtain the positive electrode material through shear mixing;

[0085] Then press the positive electrode material into a 200-μm positive electrode precursor through multi-roll transfer;

[0086] Finally, irradiate the positive electrode precursor with ultraviolet light at 400 nm and 600 mW / cm2 Irradiate for 100 s under a UV device with a certain intensity (e.g., a UV lamp) to obtain the positive electrode sheet required for assembling the battery.

[0087] The preparation steps of the negative electrode sheet are as follows:

[0088] Mix 4.8 kg of artificial graphite, 50 g of conductive carbon black, 50 g of 1,6 - hexanediol diacrylate (HDDA), and 50 g of 2 - hydroxy - 2 - methylpropiophenone and stir evenly;

[0089] Then add 50 g of polytetrafluoroethylene and obtain the negative electrode material through shear mixing;

[0090] Further, press the negative electrode material into a negative electrode precursor with a thickness of 100 μm through multi - roll transfer;

[0091] Finally, irradiate the negative electrode precursor under a UV device with a wavelength of 200 nm and a power density of 500 mW / cm 2 for 80 s to obtain the negative electrode sheet required for assembling the battery. That is, the positive / negative electrode sheets obtained through the above steps can be directly applied to the assembly of dry battery cells without going through heating and baking.

[0092] Secondly, prepare a quasi - solid - state battery. The preparation steps of the quasi - solid - state battery are as follows:

[0093] Assemble the positive electrode sheet, negative electrode sheet, and separator prepared above into a dry battery cell in a stacking manner. Among them, a PE - based membrane with a thickness of 9 μm is selected as the separator;

[0094] Inject electrolyte into the assembled dry battery cell to obtain a battery cell (that is, directly inject electrolyte into the dry battery cell assembled based on the positive / negative electrode sheets obtained through the above steps without going through baking and drying). Among them, a fluorine - containing ionic liquid electrolyte with a lithium salt concentration of 1 mol / L is selected as the electrolyte, and the injection volume coefficient is 0.8 g / Ah.

[0095] Example 2

[0096] The difference from Example 1 is that in this example, the injection volume coefficient of the battery cell is 1.0 g / Ah.

[0097] Example 3

[0098] The difference from Example 1 is that in this example, the injection volume coefficient of the battery cell is 1.5 g / Ah.

[0099] Example 4

[0100] In this example, the ratio of the positive / negative electrode materials is different from that in Example 1. Among them,

[0101] The positive electrode material includes: 4.485 kg of lithium iron phosphate, 10 g of conductive carbon black, 250 g of dipropylene glycol diacrylate, 250 g of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 5 g of polytetrafluoroethylene.

[0102] The negative electrode material includes: 4.690 kg of artificial graphite, 5 g of conductive carbon black, 150 g of 1,6-hexanediol diacrylate and 150 g of 2-hydroxy-2-methylpropiophenone are mixed and stirred evenly, and 5 g of polytetrafluoroethylene.

[0103] Example Five

[0104] The positive electrode polymer and the positive electrode polymer initiator in this example are different from those in Example One, where

[0105] The positive electrode polymer monomer is trimethylolpropane triacrylate, and the positive electrode polymer initiator is a thioxanthone initiator.

[0106] Example Six

[0107] The negative electrode polymer and the negative electrode polymer initiator in this example are different from those in Example One, where

[0108] The negative electrode polymer is ethoxylated bisphenol A diacrylate, and the negative electrode polymer initiator is 1-hydroxycyclohexyl phenyl ketone.

[0109] Example Seven

[0110] The positive electrode polymer monomer and the negative electrode polymer initiator in this example are different from those in Example One, where

[0111] The positive electrode polymer monomer is trimethylolpropane triacrylate, and the negative electrode polymer initiator is 1-hydroxycyclohexyl phenyl ketone.

[0112] Example Eight

[0113] The parameters for ultraviolet curing of the positive / negative electrode precursors in this example are different from those in Example One, where

[0114] The positive electrode precursor is irradiated under a UV device (e.g., UV lamp) with a wavelength of 50 nm and an intensity of 700 mW / cm 2 for 150 s to obtain the positive electrode sheet required for assembling the battery.

[0115] The negative electrode precursor is irradiated under a UV device with a wavelength of 80 nm and an intensity of 400 mW / cm 2 for 180 s to obtain the negative electrode sheet required for assembling the battery.

[0116] Example Nine

[0117] In this embodiment, the parameters for ultraviolet curing of the positive / negative electrode precursors are different from those in Embodiment 1. Among them,

[0118] The positive electrode precursor is irradiated under a UV device (e.g., UV lamp) with a wavelength of 380 nm and an intensity of 200 mW / cm 2 for 30 s to obtain the positive electrode sheet required for assembling the battery.

[0119] The negative electrode precursor is irradiated under a UV device with a wavelength of 380 nm and an intensity of 200 mW / cm 2 for 30 s to obtain the negative electrode sheet required for assembling the battery.

[0120] Embodiment 10

[0121] In this embodiment, the parameters for ultraviolet curing of the positive / negative electrode precursors are different from those in Embodiment 1. Among them,

[0122] The positive electrode precursor is irradiated under a UV device (e.g., UV lamp) with a wavelength of 250 nm and an intensity of 350 mW / cm 2 for 80 s to obtain the positive electrode sheet required for assembling the battery.

[0123] The negative electrode precursor is irradiated under a UV device with a wavelength of 250 nm and an intensity of 350 mW / cm 2 for 80 s to obtain the negative electrode sheet required for assembling the battery.

[0124] Comparative Example 1

[0125] Preparation of the positive electrode sheet: 4.75 kg of lithium iron phosphate, 100 g of conductive carbon black, 50 g of PVDF, and 2 kg of NMP are mixed and stirred evenly, and then coated, rolled, and die-cut to obtain the required positive electrode sheet;

[0126] Preparation of the negative electrode sheet: 4.75 kg of artificial graphite, 50 g of conductive carbon black, 50 g of CMC, and 3 kg of deionized water are mixed and stirred evenly, and then coated, rolled, and die-cut to obtain the required negative electrode sheet;

[0127] The above positive and negative electrode sheets are assembled into a liquid battery. The separator is a PE-based film with a thickness of 99 μm. The electrolyte salt is 1 mol / L LiPF6, and the solvent is EC / EMC / DEC = 1:1:1.

[0128] Comparative Example 2

[0129] The difference from Embodiment 1 is that in this comparative example, a conventional electrolyte is used. The lithium salt is 1 mol / L LiPF6, the solvent is EC:DMC = 3:7, and the injection coefficient is 1.6 g / Ah.

[0130] Comparative Example 3

[0131] The difference from Comparative Example 1 is that in this comparative example, the electrolyte uses a fluoride ion-containing ionic liquid electrolyte with a lithium salt concentration of 1 mol / L, and the injection volume is 0.8 g / Ah.

[0132] Please refer to Figure 2 , Figure 2 shows the change effect diagram of the swelling force of the battery cells in Example 1 and Comparative Example 1 with the number of cycles. As the cycling continues, the swelling forces of the battery cells in Example 1 and Comparative Example 1 both increase with the increase in the number of cycles. Among them, after 200 cycles, the swelling force of the battery cell in Example 1 reaches about 1.37 kN, and after 200 cycles, the swelling force of the battery cell in Comparative Example 1 is close to 3.92 kN.

[0133] Although the battery cell can still achieve a capacity retention rate of more than 80% after 200 cycles under the charge-discharge regime of 0.5C charge / 1C discharge, the battery cell cannot pass the 5-mm steel needle test and the 150°C / 1h hot box test.

[0134] Please refer to Table 1. Table 1 shows a partial test data comparison table of the cycling of the battery cells in Examples 1 to 10 and Comparative Examples 1 to 3. The experimental data of each group of battery cells is the average value of the experimental data of this group of battery cells, and the number of battery cells in each group is 10.

[0135] Table 1

[0136] Retention rate at 200 cycles 5mm steel needle test 150℃ / 1h hot box test Example 1 87％ Passed Passed Example 2 88％ Passed Passed Example 3 84％ Passed Passed Example 4 81％ Passed Passed Example 5 86％ Passed Passed Example 6 85％ Passed Passed Example 7 86％ Passed Passed Example 8 85％ Passed Passed Example 9 85％ Passed Passed Example 10 83％ Passed Passed Control Example 1 89％ Failed Failed Control Example 2 53％ Failed Failed Control Example 3 38％ Passed Passed

[0137] As shown in Table 1, after 200 cycles, the battery cells provided in Examples 1 to 10 can all achieve a capacity retention rate of more than 80%, and the attenuation is not obvious. However, after 200 cycles, the capacity retention rates of Comparative Example 2 and Comparative Example 3 are lower than 55%, and the cycling performance is poor. Moreover, the battery cells provided in Examples 1 to 10 can all pass the 5-mm steel needle test and the 150°C / 1h hot box test, and no swelling phenomenon occurs in the battery cells during the hot box test. However, the battery cells provided in Comparative Example 1 and Comparative Example 2 do not pass the 5-mm steel needle test and the 150°C / 1h hot box test.

[0138] The above embodiments merely illustrate the principles and effects of the present application and are not used to limit the present application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present application should still be covered by the claims of the present application.

Claims

1. A method for manufacturing a quasi-solid-state battery, characterized in that: The following steps are involved: Prepare at least one of the positive electrode sheet and the negative electrode sheet based on an ultraviolet in-situ curing method; Assembling the positive electrode sheet, the separator and the negative electrode sheet to obtain a dry battery cell; A fluorine-containing ionic liquid electrolyte is injected into the dry battery core, and the fluorine-containing ionic liquid infiltrates the dry battery core and forms an organic-inorganic composite interface film.

2. The method for manufacturing a quasi-solid-state battery according to claim 1, characterized in that: The UV in-situ curing method comprises: Obtaining active materials, polymer monomers and polymer initiators and mixing them to obtain electrode materials; Pressing and laminating the electrode materials to obtain an electrode precursor; The electrode precursor is subjected to UV in-situ curing to obtain the positive electrode sheet and / or the negative electrode sheet, and the polymer monomer forms a polymer component after the UV in-situ curing.

3. The method for manufacturing a quasi-solid-state battery according to claim 2, characterized in that: The positive electrode sheet is prepared based on the ultraviolet in-situ curing method, including the steps of obtaining positive electrode active materials, positive electrode polymer monomers and positive electrode polymer initiators; wherein, The positive electrode active material includes at least one of lithium iron phosphate, nickel-cobalt-manganese ternary material, lithium manganese iron phosphate and lithium manganate; and / or, The positive electrode polymer monomer includes at least one of tripropylene glycol diacrylate and trimethylolpropane triacrylate; and / or, The positive electrode polymer initiator includes at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and thioxanthone initiators.

4. The method for manufacturing a quasi-solid-state battery according to claim 2, characterized in that: The negative electrode sheet is prepared based on the ultraviolet in-situ curing method, including the steps of obtaining negative electrode active materials, negative electrode polymer monomers and negative electrode polymer initiators; wherein, The negative electrode active material includes at least one of a graphite material, a silicon-based material and a tin-based material; and / or, The negative electrode polymer monomer includes at least one of 1,6-hexanediol diacrylate and ethoxylated bisphenol A diacrylate; and / or, The negative electrode polymer initiator includes at least one of 2-hydroxy-2-methylpropiophenone and 1-hydroxycyclohexyl benzophenone.

5. The method for manufacturing a quasi-solid-state battery according to claim 2, characterized in that: The electrode precursor is UV-cured in situ by UV irradiation under preset conditions, wherein the preset conditions include at least one of the following conditions: The wavelength range of the ultraviolet light is 10nm-400nm; The intensity range of the ultraviolet light is 200mW / cm 2 -700 mW / cm 2 ; The irradiation time of the ultraviolet light ranges from 10s to 180s.

6. The method for manufacturing a quasi-solid-state battery according to claim 2, characterized in that: In terms of mass percentage, the electrode material comprises: The active material accounts for 70% to 98%; and / or, The polymer monomer accounts for 1%-5%; and / or, The proportion of the polymer initiator is in the range of 0.1%-3%.

7. The method for manufacturing a quasi-solid-state battery according to claim 2, characterized in that: The electrode material also includes at least one of a conductive agent and a binder; wherein, The conductive agent includes at least one of carbon nanotubes, graphene and conductive carbon black; and / or, The proportion of the conductive agent is 0.01%-5%; and / or, The binder comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber and carboxymethyl cellulose; and / or, The binder accounts for 0.1%-5%.

8. The method for manufacturing a quasi-solid-state battery according to any one of claims 1 to 7, characterized in that: The fluorine-containing ionic liquid electrolyte comprises a fluorine-containing ionic liquid and a lithium salt. The fluorine-containing ionic liquid comprises 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, and the lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide.

9. The method for manufacturing a quasi-solid-state battery according to claim 8, characterized in that: The injection volume coefficient of the fluorine-containing ion liquid electrolyte injected into the dry battery cell is in the range of 0.1 g / Ah-1.5 g / Ah; the concentration range of the lithium salt is in the range of 0.1 mol / L-5 mol / L.

10. A quasi-solid-state battery, characterized in that: The quasi-solid-state battery includes a dry cell and a fluorine-containing ionic liquid electrolyte, wherein the dry cell includes a positive electrode sheet, a separator and a negative electrode sheet, wherein at least one of the positive electrode sheet and the negative electrode sheet is prepared based on an ultraviolet in-situ curing method, and the fluorine-containing ionic liquid is configured to infiltrate the dry cell and form an organic-inorganic composite interface film.

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