A detection device and a method for detecting lithium plating using the device.

Abstract

This application relates to a detection device comprising an electrode assembly including a negative electrode, a positive electrode, and a separator; an output terminal disposed substantially horizontally opposite the end face of the negative electrode; insulating portions disposed on both sides of the output terminal for fixing the output terminal; and a detection component connected to the output terminal and the negative electrode for acquiring the resistance value between the output terminal and the negative electrode. This application also relates to a method for detecting lithium plating in lithium-ion batteries using the aforementioned detection device, and the application of the detection device for detecting lithium plating in lithium-ion batteries.

Description

Technical Field

[0001] This application relates to a detection device comprising an electrode assembly arranged in a specific configuration and a detection component connected thereto. This application also relates to a method for detecting lithium plating in lithium-ion batteries using the aforementioned detection device, and the use of the aforementioned detection device for detecting lithium plating in lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries have become the most popular energy storage system due to their low cost, long lifespan, and high safety, and are now widely used in pure electric vehicles, hybrid electric vehicles, and smart grids. However, lithium-ion batteries pose a risk of lithium deposition during charging. Especially during high-current fast charging or low-temperature charging, the rate at which lithium ions embed into the anode is slower than the rate at which they conduct to the anode active material, leading to the deposition of metallic lithium on the surface of the negative electrode. This deposition typically forms dendritic lithium crystals, or lithium dendrites. Lithium dendrites readily react with the electrolyte in various ways, generating large amounts of gas and heat. Furthermore, lithium dendrites can puncture the separator, causing short circuits or even combustion and explosion in the lithium battery. Current technologies primarily aim to minimize lithium deposition by modifying the negative electrode to improve its mechanical properties or by adding additives to the electrolyte. However, lithium dendrite deposition is almost unavoidable during the lifespan of commercial lithium-ion batteries. Therefore, there is a widespread need to suppress lithium dendrite growth and improve battery safety.

[0003] Current research on lithium dendrites is insufficient, especially regarding the monitoring and real-time detection of lithium dendrite precipitation and growth during charging. Without effective detection methods, efforts to suppress lithium dendrites will be even more difficult.

[0004] Therefore, there is a need in the art for a device and method that can monitor, especially detect in real time, lithium ion deposition during the charging process of lithium-ion batteries, which can significantly improve the research on suppressing lithium deposition in the field. Summary of the Invention

[0005] This application is made in view of the above-mentioned problems, and its purpose is to provide a detection device that can provide an effective means of monitoring and detecting lithium deposition in real time in the field of lithium-ion batteries, thereby solving the technical problem of the lack of effective means to effectively detect lithium deposition during the charging process of lithium-ion batteries in the prior art.

[0006] To achieve the above objectives, the first aspect of this application provides a detection device, including an electrode assembly comprising a negative electrode, a positive electrode, and a separator; an output terminal disposed substantially horizontally opposite to the end face of the negative electrode; and insulating portions disposed on both sides of the output terminal for fixing the output terminal.

[0007] The detection component is connected to the output terminal and the negative electrode plate, and is used to collect the resistance value between the output terminal and the negative electrode plate.

[0008] By measuring the resistance between the output terminal and the negative electrode using a detection component, the lithium-ion deposition on the end face of the negative electrode facing the output terminal can be reflected in real time, which is the process of lithium dendrite growth and passivation. This detection is highly accurate and intuitive, providing an effective analytical method for lithium-ion battery lithium deposition phenomena.

[0009] In any embodiment, the negative electrode is disposed between the two positive electrodes, and the positive electrode is 0.5-2.5 mm longer than the negative electrode on the side near the output terminal, optionally 0.8-1.5 mm. Setting the length of the positive electrode beyond the negative electrode within a specific range allows for better control of lithium deposition on the end face of the negative electrode.

[0010] In any embodiment, the thickness of the insulating portion is 100-500 μm, optionally 150-300 μm. This thickness of insulating portion can effectively fix the output terminal in a specific position and insulate it from other electrodes.

[0011] In any embodiment, the output terminal is provided with a first insulating element for isolating the positive electrode from the output terminal. In some embodiments, the thickness of the first insulating element is 5-50 μm, optionally 10-30 μm. In some embodiments, the first insulating element is selected from one or more of polyolefins, polyurethanes, polyacrylates, polyesters, polystyrene, polyvinyl chloride, natural rubber, neoprene rubber, epoxy resins, silicone resins, and compounds comprising them. The first insulating element ensures that lithium dendrites grow on the end face of the output terminal and not on the side face of the output terminal.

[0012] In any embodiment, the difference in width between the end face of the output terminal and the end face of the negative electrode is less than 5 μm, optionally less than 3 μm, and more optionally, the two widths are the same. In some embodiments, the distance between the end face of the output terminal and the end face of the negative electrode is 0.5-2.5 mm, optionally 0.5-2 mm, and more optionally 0.8-1.5 mm. This setting helps to regulate the growth of lithium dendrites and is beneficial for producing a stable resistance value.

[0013] In any embodiment, the positive electrode and the output terminal do not overlap longitudinally. This arrangement prevents interaction between the positive electrode and the output terminal, thus avoiding any impact on the resistance measurement.

[0014] In any implementation scheme, the detection mechanism is an internal resistance meter.

[0015] In any embodiment, the output terminal is made of copper foil.

[0016] In any embodiment, the detection device is used to monitor the lithium plating of the battery, wherein the lithium plating is the precipitation or growth of lithium dendrites.

[0017] A second aspect of this application provides a method for detecting lithium plating in a lithium-ion battery, comprising using a detection device selected from the first aspect of this application, wherein the detection device is charged and the resistance value between the output terminal and the negative electrode is acquired through the detection component. The method enables real-time detection of lithium dendrite deposition and growth, and provides means for qualitative and quantitative analysis.

[0018] A third aspect of this application provides a detection apparatus selected from the first aspect of this application for detecting lithium plating in lithium-ion batteries. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0020] Figure 1 This is a side view of an electrode assembly included in a detection device according to one embodiment of this application, wherein the detection component is not shown.

[0021] Figure 2 A schematic diagram of the detection component of the detection device in one embodiment of this application is shown.

[0022] Figure 3 This is a graph showing the change in resistance value measured by a detection device as the temperature rises from 25°C to 60°C and is left to stand for different periods of time, according to one embodiment of this application.

[0023] Explanation of reference numerals in the attached figures

[0024] 1 Output terminal

[0025] 2. Negative electrode plate

[0026] 3 Positive electrode sheet

[0027] 4. Separating membrane

[0028] 5. Insulation section

[0029] 6 First Insulator

[0030] 7. Detection components Detailed Implementation

[0031] For the sake of brevity, this application specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0032] After multiple charge-discharge cycles during use, lithium-ion batteries inevitably experience lithium plating. This is primarily because the rate of lithium ion insertion into the anode is less than the rate of lithium ion migration to the anode active material. This results in the remaining lithium ions, unable to insert into the anode, depositing as metallic lithium on the surface of the negative electrode. This metallic lithium typically manifests as dendritic crystals, known as lithium dendrites. Lithium dendrites have a high specific surface area, making them prone to various side reactions with the electrolyte, increasing gas production and reducing battery capacity. When lithium dendrites grow excessively, they can puncture the separator, leading to short circuits or even combustion and explosion. While some methods for suppressing lithium dendrite growth have been developed, there are no effective means to observe the deposition and growth of lithium dendrites, no intuitive studies on the changes in lithium dendrites with temperature and time, and no effective methods to evaluate the effectiveness of suppressing lithium dendrite deposition and growth.

[0033] Through research, the inventors discovered that by constructing an electrode assembly with a special three-electrode structure and connecting it to a detection component capable of measuring the resistance between the electrodes, a detection device capable of effectively detecting lithium dendrite precipitation and growth can be obtained.

[0034] Specifically, the first aspect of this application provides a detection device, comprising:

[0035] An electrode assembly includes a negative electrode, a positive electrode, and a separator; an output terminal disposed approximately horizontally opposite the end face of the negative electrode; and insulating portions disposed on both sides of the output terminal for fixing the output terminal.

[0036] The detection component is connected to the output terminal and the negative electrode plate, and is used to collect the resistance value between the output terminal and the negative electrode plate.

[0037] Unbound by any theory, the inventor believes that during the charging process of a lithium-ion battery, Figure 1Taking the structure shown as an example, since the positive electrode 3 is slightly longer than the negative electrode 2 on one side, lithium ions are relatively concentrated on the side of the negative electrode 2 that is shorter than the positive electrode 3 and opposite to the output terminal 1, and lithium dendrites are deposited during charging. As the charging process continues, the lithium dendrites continue to grow and extend from the side of the negative electrode 2 toward the end face of the output terminal 1, which is roughly horizontal and opposite to it. The output terminal 1 and the negative electrode 2 are connected by the detection component 7, and the resistance value between the output terminal 1 and the negative electrode 2 is continuously collected. During the continuous growth and extension of the lithium dendrites, as the tip of the lithium dendrites gets closer to the end face of the output terminal 1, the resistance value between the output terminal 1 and the negative electrode 2 collected by the detection component 7 will theoretically show a continuous decreasing trend. When the lithium dendrites finally extend to the end face of the output terminal 1 and overlap with it, a short circuit is formed between the output terminal 1 and the negative electrode 2. At this point, the resistance value between the output terminal 1 and the negative electrode 2, collected by the detection component 7, will show a sharp decrease, theoretically even approaching zero. However, during actual charging, lithium dendrites undergo various side reactions with the electrolyte, forming a passivation layer of a certain thickness on their surface. This passivation layer causes the resistance value between the output terminal 1 and the negative electrode 2, collected by the detection component 7, to be in a relatively low resistance range above zero. When left to stand at room temperature for an extended period under these conditions, the resistance value will eventually stabilize at a lower value.

[0038] By measuring the resistance between the output terminal 1 and the negative electrode 2 using the detection component 7, the deposition of lithium ions on the end face of the negative electrode 2 facing the output terminal 1 can be detected in real time, which is the process of lithium dendrite growth. The more the lithium dendrites grow, the closer their tips are to the end face of the output terminal 1 opposite to the negative electrode 2, and the resistance value between the output terminal 1 and the negative electrode 2 collected by the detection component 7 decreases. This detection is very accurate and intuitive, providing an effective means of analyzing lithium deposition in lithium-ion batteries. By plotting the resistance value between the output terminal 1 and the negative electrode 2 collected by the detection component 7 against the corresponding time, a functional relationship between the resistance value and time can be obtained, which reflects the state of lithium dendrite deposition and growth over time.

[0039] In some embodiments, the negative electrode 2 is disposed between the two positive electrode 3s, and the positive electrode 3 is 0.5-2.5 mm longer than the negative electrode 2 on the side near the output terminal 1, optionally 0.8-1.5 mm. Because the positive electrode 3 is longer than the negative electrode 2 on the side near the output terminal 1, lithium dendrites will inevitably precipitate and grow on the end face of the negative electrode 2 near the output terminal 1 when the lithium-ion battery is charged. By setting the length of the positive electrode 3 exceeding the negative electrode 2 within a specific range, the precipitation of lithium on the end face of the negative electrode 2 can be better controlled.

[0040] In some embodiments, the insulation portion 5 has a thickness of 100-500 μm, optionally 150-300 μm. This thickness of insulation portion 5 effectively secures the output terminal 1 in a specific position and insulates it from other electrodes. The insulation portion 5 can be one or more of polyolefins, polyurethanes, polyacrylates, polyesters, polystyrene, polyvinyl chloride, natural rubber, neoprene rubber, epoxy resins, silicone resins, and composites thereof, optionally polyolefins, polyurethanes, polyacrylates, and polyesters. In some embodiments, the insulation portion 5 is disposed horizontally opposite the positive electrode 3. In other embodiments, the insulation portion 5 and the positive electrode 3 have approximately the same thickness.

[0041] In some embodiments, the output terminal 1 is provided with a first insulating member 6, which isolates the positive electrode 3 from the output terminal 1. In some embodiments, the thickness of the first insulating member 6 is 5-50 μm, optionally 10-30 μm. In other embodiments, the first insulating member 6 is selected from one or more of polyolefins, polyurethanes, polyacrylates, polyesters, polystyrene, polyvinyl chloride, natural rubber, neoprene rubber, epoxy resins, silicone resins, and compounds containing the same. The first insulating member 6 may cover all sides of the output terminal 1 except for the end face, or even all surfaces of the output terminal 1 except for the end face opposite the negative electrode 2, leaving only the end face opposite the negative electrode 2 exposed to the outside. The first insulating member 6 ensures that lithium dendrites overlap on the end face of the output terminal 1 opposite the negative electrode 2 without interfering with other sides of the output terminal 1.

[0042] In some embodiments, the difference in width between the end face of the output terminal 1 and the end face of the negative electrode 2 is less than 5 μm, optionally less than 3 μm, and further optionally the two widths are the same. In some embodiments, the distance between the end face of the output terminal 1 and the end face of the negative electrode 2 is 0.5-2.5 mm, optionally 0.5-2 mm, and further optionally 0.8-1.5 mm. These settings help regulate the growth of lithium dendrites and facilitate the generation of stable resistance values.

[0043] In some implementations, the positive electrode 3 and the output terminal 1 do not overlap longitudinally. This arrangement avoids interaction between the positive electrode 3 and the output terminal 1, thus preventing any impact on the resistance measurement.

[0044] In some embodiments, the detection mechanism is an internal resistance meter. The detection mechanism can also be any other device capable of detecting internal resistance values. The internal resistance meter can be a situ-mounted internal resistance meter. In some embodiments, the output terminal 1 is made of copper foil. It is understood that the output terminal 1 can also be made of other suitable materials.

[0045] In some implementations, the detection device is used to monitor lithium plating in the battery, wherein the lithium plating is the precipitation or growth of lithium dendrites.

[0046] A second aspect of this application provides a method for detecting lithium plating in a lithium-ion battery, comprising using a detection device selected from those described above, wherein the detection device is charged and the resistance value between the output terminal 1 and the negative electrode 2 is acquired by the detection component 7. The method enables real-time detection of lithium dendrite deposition and growth, and provides means for qualitative and quantitative analysis.

[0047] A third aspect of this application provides a device selected from the detection apparatus described above for detecting lithium plating in lithium-ion batteries.

[0048] The electrode assembly of the detection device will be described in detail below.

[0049] Typically, a lithium-ion battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The separator, positioned between the positive and negative electrodes, serves as a barrier. The electrolyte, acting as a conductor between the positive and negative electrodes, facilitates ion exchange.

[0050] Electrolyte

[0051] The detection device according to this application includes an electrolyte. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The electrolyte includes an electrolyte salt and a solvent.

[0052] In this application, the electrolyte salt can be a commonly used electrolyte salt in lithium-ion batteries, such as a lithium salt, including lithium salts that can be used as high thermal stability salts, lithium salts that can be used as low impedance additives, or lithium salts that can inhibit aluminum foil corrosion. As an example, the electrolyte salt can be selected from one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiAsF6 (lithium hexafluoroarsenate), LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate borate), LiPO2F2 (lithium difluorophosphate), LiDFOP (lithium difluorodioxalate phosphate), LiSO3F (lithium fluorosulfonate), NDFOP (difluorodioxalate), Li2F(SO2N)2SO2F, KFSI, CsFSI, Ba(FSI)2, and LiFSO2NSO2CH2CH2CF3.

[0053] There are no particular restrictions on the type of solvent, which can be selected according to actual needs. In some embodiments, the solvent is a non-aqueous solvent. Optionally, the solvent may include one or more of chain carbonates, cyclic carbonates, and carboxylic acid esters. In some embodiments, the solvent may be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), tetrahydrofuran, sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0054] In some embodiments, the electrolyte may optionally include other additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, battery high-temperature performance, and battery low-temperature performance. As an example, the additives are selected from at least one of the following: cyclic carbonate compounds containing unsaturated bonds, halogen-substituted cyclic carbonate compounds, sulfate compounds, sulfite compounds, sulfonyl lactone compounds, disulfonic acid compounds, nitrile compounds, aromatic compounds, isocyanate compounds, phosphonitrile compounds, cyclic anhydride compounds, phosphite compounds, phosphate compounds, borate ester compounds, and carboxylic acid ester compounds.

[0055] [Positive electrode plate]

[0056] The positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, wherein the positive active material layer includes a positive active material and a conductive agent.

[0057] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0058] The positive electrode current collector can be a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (e.g., aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0059] The positive electrode active material layer disposed on the surface of the positive electrode current collector includes a positive electrode active material. The positive electrode active material used in this application can be any conventional positive electrode active material used in secondary batteries. In some embodiments, the positive electrode active material may contain one or more selected from lithium transition metal oxides, olivine-structured lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides include, but are not limited to, one or more selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of olivine-structured lithium-containing phosphates include, but are not limited to, one or more selected from lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their modified compounds. These materials are all commercially available. Carbon may be coated on the surface of the positive electrode active material.

[0060] The positive electrode active material layer may optionally include a conductive agent. However, there is no specific limitation on the type of conductive agent, and those skilled in the art can select it according to actual needs. As an example, the conductive agent used for the positive electrode material may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0061] The positive electrode active material layer may optionally include a binder. As an example, the binder may be one or more of styrene-butadiene rubber (SBR), waterborne acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0062] In this application, the positive electrode sheet 3 can be prepared according to methods known in the art. As an example, a carbon-coated positive electrode active material, a conductive agent, and a binder can be dispersed in a solvent (e.g., N-methylpyrrolidone (NMP)) to form a uniform positive electrode slurry; the positive electrode slurry is coated onto a positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained.

[0063] [Negative electrode plate]

[0064] The negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the negative electrode material layer including a negative electrode active material.

[0065] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0066] In the electrode assembly of this application, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (e.g., copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0067] In the electrode assembly of this application, the negative electrode material layer typically comprises a negative electrode active material and optional binders, optional conductive agents, and other optional additives, and is usually formed by coating and drying a negative electrode slurry. The negative electrode slurry coating is typically formed by dispersing the negative electrode active material, optional conductive agents, and binders in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water.

[0068] The specific type of negative electrode active material is not limited; any active material known in the art that can be used as the negative electrode of a lithium-ion secondary battery can be used. Those skilled in the art can select according to actual needs. As an example, the negative electrode active material can be selected from one or more of graphite, soft carbon, hard carbon, mesophase carbon microspheres, carbon fibers, carbon nanotubes, elemental silicon, silicon oxides, silicon-carbon composites, and lithium titanate.

[0069] As an example, the conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0070] As an example, the adhesive may be selected from one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0071] Other optional additives include thickeners (such as sodium carboxymethyl cellulose (CMC-Na)).

[0072] [Isolation membrane]

[0073] The electrode assembly using an electrolyte also includes a separator membrane. The separator membrane is disposed between the positive and negative electrode plates, serving as a separator. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. In some embodiments, the material of the separator membrane can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0074] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0075] In some embodiments, the electrode assembly may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and the electrolyte.

[0076] In some embodiments, the outer packaging of the electrode assembly can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the electrode assembly can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0077] This application does not impose any particular limitation on the shape of the electrode assembly of the detection device; it can be cylindrical, square, or any other arbitrary shape. Figure 1 This is a side view of the electrode assembly of the detection device according to this application, which includes a negative electrode 2, a positive electrode 3, an output terminal 1, a separating membrane 4, an insulating portion 5, and a first insulating member 6. Electrolyte fills the space between the negative electrode 2 and the positive electrode 3, unless otherwise specified. The detection component 7 is schematically shown in... Figure 2 In the middle, it connects the negative electrode plate 2 (specifically the negative electrode tab) to the output terminal 1.

[0078] Example

[0079] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0080] Preparation of the detection device:

[0081] LiNi, the positive electrode active material 0.8 Co 0.1 Mn0.1 O2, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 95.5:2.5:2. The mixture was then coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode 3. Artificial graphite (anode active material), conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were thoroughly mixed in a deionized water solvent system at a mass ratio of 96.5:1.5:1:1. The mixture was then coated onto copper foil, dried, and cold-pressed to obtain the negative electrode 2. A conventional 1 mol / L LiPF6 (ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + dimethyl carbonate (DMC) = 1:1:1 (V / V / V)) was used as the electrolyte. A copper foil electrode was used as the output terminal 1, with a thickness approximately the same as that of the negative electrode 2. A polypropylene film was used as the separator 4.

[0082] The manufacturing process of the detection device is carried out in a drying room. The non-end faces of the copper foil electrode are insulated with 20μm thick PET adhesive. A 200μm thick Mylar film is used as insulation 5 on both sides of the copper foil electrode to clamp it, fixing it in a position horizontally opposite to the negative electrode 2. The distance between the end face of the copper foil electrode and the end face of the negative electrode 2 is 1.2mm. The positive electrode 3 is 0.8mm longer than the negative electrode 2 on one side of the copper foil electrode. The positive electrode 3, the separator 4, the negative electrode 2, and the copper foil electrode are arranged in... Figure 1 The electrodes are arranged in the order shown and then wound to obtain the electrode assembly. The electrode assembly is placed in the battery casing, dried, and then injected with electrolyte. The copper foil electrode and the tab of the negative electrode 2 are connected through a HT3562 internal resistance meter installed in situ.

[0083] Example 1

[0084] Testing process:

[0085] The detection device prepared as described above was formed using a charging rate of 0.1C. After formation, it was charged at a constant current of 0.33C to 4.25V. After reaching the cutoff voltage, it was charged at a constant voltage while the device was at room temperature (25℃). After the internal resistance of the device stabilized, it was transferred to an oven at 45℃ and allowed to stand. The change in resistance between the copper foil electrode and the negative electrode 2 was observed by an internal resistance meter.

[0086] Examples 2-4 and Comparative Example 1 used the same detection device as Example 1. Except for the parameters in Table 1, the methods and detection procedures were the same as in Example 1. Specific experimental conditions are detailed in [link to specific experimental settings].

[0087] Table 1.

[0088] Group Standing temperature resting time Comparative Example 1 25℃ 0h Example 1 60℃ 12h Example 2 60℃ 24h Example 3 60℃ 36h Example 4 60℃ 48h

[0089] Short-circuit internal resistance tests were performed on the devices of Examples 1-4 and Comparative Example 1, and the test results are shown in Table 2. The same testing device was used for Comparative Example 1 and Examples 1-4. After the charging process described above, the device was kept at 25°C, and its stable internal resistance value was measured, which is the short-circuit internal resistance of Comparative Example 1. Then, the device was heated to 60°C and left to stand at this temperature for 12h, 24h, 36h, and 48h, respectively, and the internal resistance values ​​were measured, which are the short-circuit internal resistances of Examples 1, 2, 3, and 4, respectively. The internal resistance values ​​were measured in real time; that is, the temperature at the time of measurement was the same as the temperature at the time of standing. Table 2 below summarizes the short-circuit internal resistance test results of Examples 1-4 and Comparative Example 1.

[0090] Table 2. Short-circuit internal resistance test results of Examples 1-4 and Comparative Example 1

[0091]

[0092]

[0093] As shown in Table 2, the internal resistance values ​​between the negative electrode 2 and the copper foil electrode in the detection device, as measured by the internal resistance meter, exhibit significant differences at different temperatures, and also change over time when left to stand at the same temperature. Specifically, after standing for 12 hours at elevated temperatures, the detected internal resistance increases significantly; with increasing standing time, the internal resistance also increases by different factors. For example, when the detection device is in a stable state at 25°C, lithium dendrites continuously grow from the end face of the negative electrode 2 and overlap with the end face of the copper foil electrode, causing a short circuit between the negative electrode 2, the copper foil electrode, and the internal resistance meter. At this time, the resistance value approaches zero. Then, as the surface of the lithium dendrites gradually passivates, the resistance value recovers, exhibiting a stable resistance of 24Ω at 25°C (Comparative Example 1). Then, the device was heated to 60°C and left to stand. After standing for 12h, 24h, 36h and 48h, the resistance value was measured by an internal resistance meter. It was found that the resistance value increased to 400Ω, 650Ω, 720Ω and 780Ω, respectively. Figure 3 The diagram shows the change in internal resistance of the detection device over time after being heated from 25°C to 60°C. The change in internal resistance reflects the growth and passivation of lithium dendrites formed between the end face of the negative electrode 2 and the end face of the copper foil electrode.

[0094] The experimental data above demonstrates that the detection device of this invention can be used to detect lithium deposition in lithium-ion batteries, particularly the deposition, growth, and passivation of lithium dendrites between electrodes. This detection can be real-time, displaying the change in internal resistance over time, and the internal resistance value reflects the lithium dendrite growth process.

[0095] Although this application has been described with reference to embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A detection device for monitoring lithium plating in a battery, comprising: An electrode assembly includes a negative electrode, a positive electrode, and a separator; an output terminal disposed approximately horizontally opposite the end face of the negative electrode; insulating portions disposed on both sides of the output terminal for fixing the output terminal; the negative electrode is disposed between two positive electrodes, and the positive electrode is 0.5-2.5 mm longer than the negative electrode on the side closer to the output terminal; the distance between the end face of the output terminal and the end face of the negative electrode is 0.5-2.5 mm. A detection component, connected to the output terminal and the negative electrode, is used to collect the resistance value between the output terminal and the negative electrode. By measuring the resistance value between the output terminal and the negative electrode using the detection component, the deposition of lithium ions on the end face of the negative electrode facing the output terminal is detected.

2. The detection device according to claim 1, wherein the positive electrode is 0.8-1.5 mm longer than the negative electrode on the side near the output terminal.

3. The detection device according to claim 1, wherein the thickness of the insulating part is 100-500 μm.

4. The detection device according to claim 3, wherein the thickness of the insulating part is 150-300 μm.

5. The detection device according to claim 1, wherein the output terminal is provided with a first insulating member, the first insulating member being used to isolate the positive electrode from the output terminal.

6. The detection device according to claim 5, wherein the thickness of the first insulating element is 5-50 μm.

7. The detection device according to claim 6, wherein the thickness of the first insulating element is 10-30 μm.

8. The detection device according to claim 5, wherein the first insulating element is selected from one or more of polyolefins, polyurethanes, polyacrylates, polyesters, polystyrene, polyvinyl chloride, natural rubber, chloroprene rubber, epoxy resins, silicone resins, and composites containing the same.

9. The detection device according to claim 1, wherein the difference in width between the end face of the output terminal and the end face of the negative electrode is less than 5 μm.

10. The detection device according to claim 9, wherein the difference in width between the end face of the output terminal and the end face of the negative electrode is less than 3 μm.

11. The detection device according to claim 10, wherein the end face of the output terminal has the same width as the end face of the negative electrode plate.

12. The detection device according to claim 1, wherein the distance between the end face of the output terminal and the end face of the negative electrode is 0.5-2 mm.

13. The detection device according to claim 12, wherein the distance between the end face of the output terminal and the end face of the negative electrode is 0.8-1.5 mm.

14. The detection device according to any one of claims 1 to 13, wherein the positive electrode and the output terminal do not overlap in the longitudinal direction.

15. The detection device according to claim 1, wherein the detection component is an internal resistance meter.

16. The detection device according to claim 1, wherein the output terminal is made of copper foil.

17. The detection device according to claim 1, wherein the lithium deposition is the deposition or growth of lithium dendrites.

18. A method for detecting lithium plating in a lithium-ion battery, comprising using a detection device according to any one of claims 1 to 17, wherein the detection device is charged, and a resistance value between the output terminal and the negative electrode is acquired by the detection component, and the resistance value between the output terminal and the negative electrode is measured by using the detection component, and lithium ion plating is detected on the end face of the negative electrode facing the output terminal.

19. The detection apparatus according to any one of claims 1 to 17 is used for detecting lithium plating in lithium-ion batteries.

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