Composite tab structure, electrode unit, battery and battery module

Abstract

This application discloses a composite tab structure, an electrode unit, a battery, and a battery module. The composite tab structure includes: a laminated body formed by a first tab and a second tab stacked together; and a tab connecting piece connecting the laminated body; wherein the first tab is wetted with electrolyte, and the second tab has the same dimensions as the first tab. The composite tab structure disclosed in this application includes a dry tab stacked on top of the wetted tab, to avoid the risk of short circuit caused by the wet tab detaching, thereby improving the battery's manufacturing yield and long-term reliability.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a semi-solid battery and its preparation method, as well as a semi-solid battery module having the semi-solid battery. Background Technology

[0002] Semi-solid-state batteries, as a transitional technology between liquid lithium-ion batteries and all-solid-state batteries, combine the advantages of high energy density and safety, and have received widespread attention in the field of new energy vehicles in recent years. Compared with traditional liquid batteries, semi-solid-state batteries reduce the use of flammable electrolytes, thereby improving thermal stability and reducing the risk of thermal runaway. As a key connecting component between the battery's internal electrodes and external circuitry, the welding quality and mechanical stability of the tabs directly affect the battery's conductivity, cycle life, and safety. Therefore, ensuring the welding quality and mechanical stability of the tabs has become a critical point in the manufacturing of semi-solid-state batteries. Utility Model Content

[0003] To achieve the above objectives, this application discloses a composite tab structure, an electrode unit, a battery, and a battery module. The composite tab structure has a "dry-wet" composite structure, which can avoid the risk of battery short circuit caused by tab detachment.

[0004] This application provides a composite electrode structure, which may include: a laminate formed by a first electrode and a second electrode connected in layers; and an electrode connecting piece connecting the laminate; wherein the first electrode is wetted with electrolyte, and the second electrode has the same size as the first electrode.

[0005] According to some embodiments of this application, the first tab is used for fixed connection with the electrode plate; the first connecting edge of the first tab and the electrode plate and the second connecting edge of the first tab and the second tab are aligned.

[0006] According to some embodiments of this application, the first electrode and the second electrode are made of the same material.

[0007] According to some embodiments of this application, the laminated connection between the first electrode tab and the second electrode tab includes roll welding.

[0008] According to some embodiments of this application, the connection between the laminate and the tab connecting piece includes ultrasonic welding.

[0009] According to some embodiments of this application, the welding area of ​​the ultrasonic welding is covered by a sealing protective layer.

[0010] In another aspect, this application provides an electrode unit, which may include a stacked electrode layer and a current collector layer, and the electrode unit may also include a composite tab structure as described above connected to the current collector layer.

[0011] According to some embodiments of this application, the composite tab structure is connected to the edge of the current collector layer by roll welding.

[0012] This application also provides a battery that may include the electrode units as described above.

[0013] Another aspect of this application provides a battery module, which may include a plurality of semi-solid batteries arranged in sequence and electrically connected as described above.

[0014] In this application, a dry tab is superimposed and welded on top of the wet tab after it has been immersed in electrolyte, forming a "dry-wet" composite structure. The dry tab is then ultrasonically welded to the tab connecting piece. This avoids the risk of battery short circuit caused by tab detachment and the problem of weak welding strength of the tab connecting piece after ultrasonic welding, thereby improving the manufacturing yield and long-term reliability of the semi-solid-state battery.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0017] Figure 1 These are exemplary structural schematic diagrams of electrode units shown in some embodiments of this application;

[0018] Figure 2 This is another exemplary structural schematic diagram of the electrode unit shown in some embodiments of this application;

[0019] Figure 3 This is an exemplary structural schematic diagram of a composite electrode tab according to some embodiments of this application. Detailed Implementation

[0020] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application and in its specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The terms "comprising" or "including," as used in this application, mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms "and / or" or "and / or" as used in this application include any and all combinations of one or more of the associated listed items.

[0022] To achieve rapid lithium-ion migration and stable reaction during charging and discharging, a current battery fabrication method involves immersing welded electrodes and tabs in an electrolyte. The lithium salt in the electrolyte undergoes a eutectic reaction with the organic ligands in the electrodes to form a eutectic electrolyte in situ. This also promotes uniform electrolyte distribution in the transition zone between the tabs and electrodes, reducing inhomogeneity in the interface reaction after subsequent electrolyte injection. Pre-wetting makes the electrolyte distribution more uniform and reduces the risk of localized hot spots. However, residual organic solvents on the tab surface after electrolyte immersion may hinder direct contact between the subsequently welded metal tab connectors and cause interface defects due to high-temperature volatilization, increasing the risk of poor tab soldering or mechanical detachment. Simultaneously, residual electrolyte forms a liquid film on the tab surface, causing damped attenuation of ultrasonic vibration energy and hindering atomic diffusion bonding between metals.

[0023] Based on this, this application provides a composite tab structure, including a dry tab stacked on top of a wet tab after immersion, to avoid the risk of battery short circuit caused by tab detachment, and to improve the battery manufacturing yield and long-term reliability.

[0024] The following describes some preferred embodiments of this application. It should be noted that the following description is for illustrative purposes only and is not intended to limit the scope of protection of this application. The steps involved in this application may be performed precisely in sequence, or various steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0025] refer to Figures 1-3The paper provides an exemplary structural diagram of the composite tab structure and the electrode unit. Figure 1 A side view is shown after the electrode sheet is welded to the composite tab structure. Figure 2 A top view of an electrode unit consisting of electrode plates and a composite tab structure is shown. Figure 3 A schematic diagram of a composite electrode structure is shown. The composite electrode structure provided in this application may include a laminated body formed by stacked first and second electrodes, and an electrode connecting piece connecting the laminated body. Figure 1 As shown, the composite tab structure can be adapted to both the positive electrode P and the negative electrode N. The positive electrode P is slightly smaller than the negative electrode N, and is presented in... Figure 1 The first tab PT1 can be located at the center of the negative electrode N. The positive electrode P can include a positive current collector layer, such as aluminum foil. The first tab PT1 can be fixedly connected to the edge of the positive current collector layer. Exemplarily, this is achieved by roll welding. The first tab PT1 can be made of the same material as the positive current collector layer, for example, the first tab PT1 can also be aluminum foil. After welding, a roll weld area SW will be formed. After the positive electrode P and the first tab PT1 are immersed in electrolyte, the first tab PT1 and the weld area between the first tab PT1 and the positive electrode P will be penetrated by the electrolyte, weakening the connection strength, causing the electrode tab to fall off during subsequent assembly or use, and also affecting the connection between the subsequent electrode tab and the electrode connecting piece. Therefore, the composite tab structure provided in this application will include a second tab PT2 stacked on the first tab PT1. The second tab PT2 can be superimposed on the first tab PT1 by roll welding.

[0026] In some implementations, the second tab PT2 can have the same dimensions and be made of the same material as the first tab PT1. For example, both the first tab PT1 and the second tab PT2 are 0.5mm × 2mm aluminum foil. Before roll welding, the first tab PT1 can be cleaned. For example, it can be purged with an inert gas such as nitrogen, helium, or argon for 10-30 seconds to remove free electrolyte from its surface. Alternatively, it can be dried by using a liquid-absorbing material to absorb the electrolyte from the surface of the first tab PT1. The second tab PT2 can also be pretreated to improve welding activity. For example, the surface of the second tab PT2 can be plasma-treated, such as with 70W pure Ar plasma for 6 seconds.

[0027] Roll welding between the first tab PT1 and the second tab PT2 can be performed using a roll welding machine. The amplitude of the roll welding machine can be 16-20% of the thickness of either the first tab PT1 or the second tab PT2, for example, 16%, 17%, 18%, 19%, 20%, etc. Alternatively, the amplitude can be 18% of the tab thickness. The welding pressure can be 50-200 MPa, for example, 50 MPa, 100 MPa, 150 MPa, 200 MPa, etc. Alternatively, the welding pressure can be 100 MPa. The roll welding temperature can be set to 25-35℃, for example, 25℃, 27℃, 29℃, 31℃, 33℃, 35℃, etc. The roller speed can be set to 5-10 m / min, for example, 5 m / min, 6 m / min, 7 m / min, 8 m / min, 9 m / min, 10 m / min, etc., or the roller speed can be set to 8 m / min. The solder joint depth can be 0.1-0.2 mm, for example, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, etc., or the solder joint depth can be 0.15 mm. After the roll welding is completed, a laminate with a dry second electrode PT2 superimposed on top of the wet first electrode PT1 will be obtained.

[0028] In some implementations, the welding edges of the second tab PT2 and the first tab PT1 are aligned with the welding edges of the first tab PT1 and the positive current collector layer. That is, after one end of the first tab PT1 is welded to the current collector layer, the second tab PT2 is still welded to that end of the first tab PT1.

[0029] Correspondingly, the other end of the second tab PT2 can be connected to the tab connecting piece PC. This tab connecting piece PC can be, but is not limited to, nickel-plated copper, aluminum, stainless steel, titanium, or composite metals (such as aluminum-copper). The above connection can be achieved through ultrasonic welding. For example, when the laminate formed by the first tab PT1 and the second tab PT2 is ultrasonically connected to the tab connecting piece, the amplitude can be 50 μm, the pressure 45 PSI, the energy 450 J, the time 0.93 s, and the power 2088 W. After welding, an ultrasonic welding zone UW can be formed between the two.

[0030] The ultrasonic welding area (UW) can also be covered with a sealing protective layer. For example, a resin with properties such as heat resistance, oxygen resistance, moisture resistance, and chemical resistance can be coated onto the ultrasonic welding area (UW) and cured to form the sealing protective layer. Methods such as thermosetting, photocuring, and free radical curing can all be used and are not limited thereto. The electrode unit is then obtained. In some implementations, the sealing protective layer can be formed using epoxy-modified silicone, or one or more of polyurethane (PU)-based protective adhesives, acrylic adhesives, silicone resins, fluororubber (FKM) coatings, and parylene vapor deposition coatings. The final composite tab structure is then obtained.

[0031] Similarly, for the negative electrode N, a negative current collector layer, such as copper foil, may also be included. (Continue to reference...) Figure 1 The corresponding first tab NT1 can be fixedly connected to the edge of the negative electrode current collector layer, for example, by roll welding. The first tab NT1 can also be made of the same material as the negative electrode current collector layer, such as copper foil. After welding, a roll welding area SW will be formed. Then, the second electrode NT2 is laminated and welded onto the first tab NT1, which has been wetted with electrolyte. For example, it is laminated and welded onto the first tab NT1 by roll welding. For the negative electrode, the first tab NT1 and the second tab NT2 also have the same size and are made of the same material. For example, both are 0.5mm × 2mm copper foil. After pretreatment (e.g., 90W Ar / O2 plasma treatment for 12 seconds), the second tab NT2 will be roll welded to the cleaned first tab NT1 (e.g., the first tab NT1 is purged with an inert gas such as nitrogen, helium, or argon for 10-30 seconds to remove surface free electrolyte). After aligning the welding edges, the above roll welding is performed using a roll welding machine. Relevant process parameters can be found in the relevant content of the positive electrode P. After roll welding, a laminate with a dry second electrode NT2 superimposed on top of a moist first electrode NT1 will be obtained. The connection between this laminate and the electrode connecting piece NC (e.g., nickel sheet, nickel-plated copper, aluminum sheet, stainless steel, titanium sheet, composite metal (e.g., aluminum-copper)) can be performed using ultrasonic welding. For example, the amplitude can be set to 50 μm, the pressure to 50 PSI, the energy to 481 J, the time to 0.5 s, and the power to 2050 W. After welding, an ultrasonically welded region UW can be formed between the two. This ultrasonically welded region UW can also be covered with a sealing protective layer. The formation method and related material selection can be found above. After completion, the final composite electrode structure will be obtained.

[0032] The first tab PT1 and the second tab PT2 mentioned above can be, but are not limited to, aluminum foil, nickel-plated aluminum, titanium foil, stainless steel, etc. The first tab NT1 and the second tab NT2 can be, but are not limited to, nickel-plated copper, stainless steel, titanium foil, graphene-copper composite foil, etc.

[0033] The composite tab structure provided in this application involves superimposing and welding a dry tab on top of a wet tab after it has been immersed in electrolyte, forming a "dry-wet" composite structure. The dry tab is then ultrasonically welded to the tab connecting piece. This avoids the risk of battery short circuits caused by tab detachment and the problem of weak welding strength of the subsequent ultrasonically welded tab connecting piece, thereby improving the manufacturing yield and long-term reliability of the semi-solid-state battery.

[0034] This application also discloses an electrode unit. The electrode unit may include stacked electrode layers and current collector layers. The electrode unit may also include a composite tab structure connected to the current collector layer. The composite tab structure may be the composite tab structure described above.

[0035] The electrode unit may include a positive electrode unit and / or a negative electrode unit. Correspondingly, the electrode layer may include a positive electrode layer or a negative electrode layer, and the current collector layer may include a positive electrode current collector layer or a negative electrode current collector layer. The positive electrode layer may include a positive electrode active material, a solid electrolyte, a first conductive agent, a first binder, and a first organic ligand; the negative electrode layer may include a negative electrode active material, a second conductive agent, a second binder, and a second organic ligand. When the first electrode tab is wetted with an electrolyte (or a first electrolyte solution, including a first lithium salt, a first organic solvent, and a first additive), the first lithium salt and the first organic ligand / second organic ligand undergo a eutectic reaction to form a eutectic electrolyte in situ on the surfaces of the positive and negative electrode layers. The first electrode tab is then permeated to form a wet electrode tab. Subsequently, it is superimposed and welded with a second electrode tab to form a laminate, and after being connected with electrode tab connecting pieces, the final electrode unit is obtained.

[0036] This application also discloses a battery, which may include the above-mentioned electrode units and a separator. Exemplarily, a dry cell is formed by sequentially stacking a positive electrode unit, a separator, and a negative electrode unit, and then injecting a second electrolyte. After standing and capacity testing, the battery is obtained. The separator includes, but is not limited to, polyolefin separators or glass fiber separators. The second electrolyte may include a second lithium salt, a second organic solvent, and a second additive.

[0037] The above-mentioned positive electrode active materials include, but are not limited to, layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium nickel cobalt manganese oxide (LiNiO2). x Co x Mn 1-2x O2, NCM), lithium nickel cobalt aluminum oxide (LiNi 0.8 Co 0.15Al 0.05 O2, NCA, etc., or compounds substituted by one or more transition metals; lithium manganese oxides such as Li 1+x Mn 2-x O4 (x is 0~0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxides such as Li2CuO2; vanadium compounds such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; with the molecular formula LiNi 1-x M x Lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, including at least one of the above elements, and x is 0.01~0.3); LiMn 2-x M x Lithium-manganese composite oxides represented by O2 (where M is Co, Ni, Fe, Cr, Zn, or Ta and x is 0.01~0.1) or the molecular formula Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiNi x Mn 2-x Spinel-type lithium-manganese composite oxides represented by O4; the Li portion in the formula LiMn2O4 is replaced by alkaline earth metal ions; LiNi x Co y Mn (1-x-y) O2 (where x=0.8, y=0.1); disulfide compounds; Fe2(MoO4)3; lithium cobalt oxide; lithium iron phosphate; elemental sulfur (S8); Li2Sn (n=1), organic sulfur compounds or carbon-sulfur polymers (C2S x ) n (x is 2.5~50, n is 2); may include sulfur-based compounds, etc.

[0038] The solid electrolytes include, but are not limited to, sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes.

[0039] The negative electrode active material includes, but is not limited to, carbonaceous materials such as graphite, hard carbon, and soft carbon, silicon, silicon-carbon mixtures, and lithium titanate (Li4Ti5O). 12 Transition metals such as Sn, metal oxides or metal sulfides such as TiO2, FeS, SnO2, etc., and lithium-indium (Li-In), etc.

[0040] The conductive agent (including the first conductive agent and the second conductive agent) may include, but is not limited to, natural graphite, artificial graphite and other graphite, conductive carbon black (Super P), acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black and other carbon black, carbon fiber such as VGCF, metal fiber and other conductive fibers, fluorinated carbon, aluminum powder, nickel powder and other metal powders, zinc oxide, potassium titanate and other conductive whiskers, titanium oxide and other conductive metal oxides, polyaniline, polypyrrole, polythiophene, polyphenylene derivatives and other conductive polymers, and one or a mixture of two or more of these.

[0041] The adhesive (including the first adhesive and the second adhesive) can be any known adhesive, including but not limited to polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aromatic polyamide resin, polyamide, polyimide, polyamide-imide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, polyhexafluoropropylene, styrene-butadiene rubber, carboxymethyl cellulose, etc., or any combination thereof, which can be used in this application. Copolymers can also be used as adhesives, exemplary of which can be copolymers of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, trifluorochloroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene, etc.

[0042] The organic ligands (including the first organic ligand and the second organic ligand) include, but are not limited to, sulfones, urea, amides, nitriles, alcohols, imidazoles and their derivatives, and crown ethers. Preferably, they include n-methylacetamide (MAc), acetamide (Ace), succinate (SN), urea, dimethyl sulfoxide (DMSO), methanol, ethylene glycol (EG), etc.

[0043] The lithium salts (including the first lithium salt and the second lithium salt) include, but are not limited to, lithium hexafluorophosphate (6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalateborate (LiDFOB), lithium perchlorate (LiClO4), lithium nitrate (LiNO3), lithium bis(oxalateborate)borate (LiBOB), lithium hexafluoroarsenate (LiAsF6), lithium difluorophosphate (LiPO2F2), lithium tetrafluoroborate (LiBF4), lithium chloride (LiCl), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), etc.

[0044] The organic solvents (including the first organic solvent and the second organic solvent) include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethyl acetate (EA), ethyl propionate (EP), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), sulfone butyrate (BDS), sulfolane cyclobutane (TMS), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), etc.

[0045] The additives (including the first additive and the second additive) include, but are not limited to, fluorocarbonate (FEC), vinylene carbonate (VC), vinyl sulfate (DTD), 1,3-propanesulfonate lactone (PS), methylene disulfonate (MMDS), trimethyl phosphate (TMP), ethyl hexafluorophosphate (FEP), tris(2,2,2-trifluoroethyl) phosphite (TFEP), lithium bis(oxalato)borate (LiBOB), citrate anhydride (CA), terephthalonitrile (PTMN), dimethylbenzoic acid (DMTB), biphenyl, cyclohexylbenzene, etc.

[0046] This application also discloses a battery module, which is formed by folding, stacking or combining multiple batteries and electrically connecting them to each other.

[0047] This application has described the basic concepts. Obviously, for those skilled in the art, the above detailed disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0048] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this application do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0049] Similarly, it should be noted that, in order to simplify the description of this application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of this application sometimes combines multiple features into one embodiment or its description. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned in the claims. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0050] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other modifications may also fall within the scope of this application. Therefore, alternative configurations of the embodiments of this application are considered as examples and not limitations, and are regarded as consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly described and illustrated in this application.

Claims

1. A composite tab structure, characterized by, The composite electrode structure includes: The laminated body formed by the first and second electrode tabs connected in a stacked manner; and A tab connecting the laminated body; wherein... The first tab is wetted with electrolyte, and the second tab has the same size as the first tab.

2. The composite tab structure of claim 1, wherein, The first tab is used for fixed connection with the electrode plate; the first connecting edge of the first tab and the electrode plate and the second connecting edge of the first tab and the second tab are aligned.

3. The composite tab structure of claim 1, wherein, The first electrode and the second electrode are made of the same material.

4. The composite tab structure of claim 1, wherein, The laminated connection between the first electrode tab and the second electrode tab includes roll welding.

5. The composite tab structure of claim 1, wherein, The connection between the laminate and the tab connector includes ultrasonic welding.

6. The composite tab structure of claim 5, wherein, The welding area of ​​the ultrasonic welding is covered by a sealing protective layer.

7. An electrode unit comprising an electrode layer and a current collector layer arranged in a stack, characterized in that The electrode unit further includes a composite tab structure as described in any one of claims 1-6, connected to the current collector layer.

8. The electrode unit of claim 7, wherein, The composite tab structure is connected to the edge of the current collector layer by roll welding.

9. A battery characterized by The battery includes the electrode unit as described in claim 7 or claim 8.

10. A battery module, characterized by The battery module includes a plurality of batteries arranged in sequence and electrically connected as described in claim 9.

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