Electrochemical device and electronic device
By designing the current collector structure and optimizing the tab groove, the problem of electrochemical performance degradation caused by the increase in energy density in the existing technology has been solved, and an electrochemical device with high energy density, long cycle life and low self-discharge has been realized.
Patent Information
- Application Number
- CN202511774119.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-06
AI Technical Summary
Existing technologies, when improving the energy density of electrochemical devices, tend to lead to deterioration of electrochemical performance, as well as poor cycle life and self-discharge rate.
The current collector structure design includes a first conductive layer, an insulating layer and a second conductive layer arranged in sequence. Through holes are opened on the conductive layer, and the insulating layer provides ion transport pores. The tab groove design avoids short circuits and lithium plating. The cell is formed by bow-shaped winding.
It improves the energy density and cycle life of electrochemical devices, reduces the self-discharge rate, enhances the lithium-ion transport rate and space utilization, and avoids lithium plating.
Smart Images
Figure CN121484080A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of energy storage technology, specifically to electrochemical devices and electronic devices. Background Technology
[0002] Electrochemical devices (especially lithium-ion batteries) are widely used in digital products, new energy vehicles, power tools, drones and other fields.
[0003] Energy density has always been a research focus in the battery industry, and improving energy density is a continuous pursuit of the industry. However, constantly adjusting the material system to improve energy density can easily lead to the deterioration of electrochemical performance. For example, existing technologies improve the energy density of electrochemical devices by increasing the positive electrode voltage, increasing the compaction density of positive and negative electrode materials, or mechanical means. However, the improvement is small and usually leads to the deterioration of electrochemical performance.
[0004] Therefore, this application is submitted. Summary of the Invention
[0005] The purpose of this application is to overcome the shortcomings of the existing technology and provide an electrochemical device and an electronic device, wherein the electrochemical device has excellent energy density, cycle life and self-discharge rate.
[0006] To achieve the above objectives, a first aspect of this application provides an electrochemical device, including a battery cell, the battery cell including a current collector, the current collector including a first conductive layer, an insulating layer and a second conductive layer disposed sequentially, the surface of the first conductive layer away from the insulating layer having a positive electrode active material layer, and the surface of the second conductive layer away from the insulating layer having a negative electrode active material layer. The first conductive layer has a plurality of first through holes, the second conductive layer has a plurality of second through holes, and the insulating layer has pores for ion transport. The positive electrode active material layer has a positive electrode tab groove and a negative electrode tab alignment groove that penetrate the positive electrode active material layer. The negative electrode active material layer has a negative electrode tab groove that penetrates the negative electrode active material layer. The negative electrode tab groove corresponds to the negative electrode tab alignment groove, and the projection of the negative electrode tab alignment groove in the thickness direction of the positive electrode active material layer covers the projection of the negative electrode tab groove in the thickness direction of the negative electrode active material layer.
[0007] In some embodiments, along the length direction of the current collector, the length of the negative electrode tab alignment groove is greater than the length of the negative electrode tab groove; and / or Along the width direction of the current collector, the width of the negative electrode tab alignment groove is greater than the width of the negative electrode plate groove.
[0008] In some embodiments, the length of the negative electrode tab alignment groove is ≥7mm.
[0009] In some embodiments, the width of the negative electrode tab alignment groove is 5.5~40mm.
[0010] In some embodiments, the length of the negative electrode tab groove is ≥6mm.
[0011] In some embodiments, the width of the negative electrode tab groove is 5~35mm.
[0012] In some embodiments, the positive electrode active material layer includes a positive electrode active material, and the electrochemical device satisfies: h1≥0.5 D1×(1-sin5°). h1 μm is the thickness of the first conductive layer; D1 μm is the Dv10 particle size of the positive electrode active material.
[0013] In some embodiments, the negative electrode active material layer comprises a negative electrode active material, and the electrochemical device satisfies: h2≥0.5 D2×(1-sin5°). h2 μm is the thickness of the second conductive layer; D2 μm is the Dv10 particle size of the negative electrode active material.
[0014] In some implementations, at least one of the following (I) to (IV) is satisfied: (I) 1≤h1≤6; (II) 1.5≤D1≤8; (III) 1≤h2≤5; (Ⅳ) 1.5≤D2≤10.5.
[0015] In some embodiments, the positive electrode active material layer includes a positive electrode active material, and the electrochemical device satisfies: 1.5×d1<d2<0.5×D3; d1 μm is the average pore size of the insulating layer; d2 μm is the average pore diameter of the first through hole; D3 μm is the Dv50 particle size of the positive electrode active material.
[0016] In some embodiments, the negative electrode active material layer comprises a negative electrode active material, and the electrochemical device satisfies: 1.5×d1<d3<0.5×D4; d1 μm is the average pore size of the insulating layer; d3 μm is the average pore diameter of the second through hole; D4 μm is the Dv50 particle size of the negative electrode active material.
[0017] In some implementations, at least one of the following (V) to (IX) is satisfied: (V) 0.02≤d1≤0.3; (VI) 0.03≤d2≤5; (VII) 3.5 ≤ D3 ≤ 19.5; (VIII) 0.03 ≤ d3 ≤ 5; (IX) 5≤D4≤18.
[0018] In some embodiments, the spacing between adjacent first through holes is 0.2~3.5 mm; and / or The spacing between adjacent second through holes is 0.2~3.5mm.
[0019] In some embodiments, the first conductive layer comprises at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy; and / or The second conductive layer comprises at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
[0020] In some embodiments, a positive electrode tab and a negative electrode tab are further included, with at least a portion of the positive electrode tab being accommodated in the positive electrode tab groove and connected to the first conductive layer, and at least a portion of the negative electrode tab being accommodated in the negative electrode tab groove and connected to the second conductive layer. In some embodiments, a first insulating adhesive layer and a second insulating adhesive layer are further included, with at least a portion of the first insulating adhesive layer covering the positive electrode tab and at least a portion of the second insulating adhesive layer covering the negative electrode tab.
[0021] In some embodiments, the current collector, the positive electrode active material layer, and the negative electrode active material layer are wound in an arc shape to form the battery cell.
[0022] A second aspect of this application provides an electronic device including the electrochemical device described above.
[0023] The beneficial effects of this application are as follows: The electrochemical device described in this application includes a current collector, which comprises a first conductive layer, an insulating layer, and a second conductive layer arranged sequentially. A positive electrode active material layer is disposed on the surface of the first conductive layer, and a negative electrode active material layer is disposed on the surface of the second conductive layer. A first through-hole and a second through-hole are respectively formed on the first and second conductive layers. Thus, the first and second conductive layers can respectively function as a positive electrode current collector and a negative electrode current collector. The insulating layer has pores for electrolyte entry. After the electrode is immersed in the electrolyte, the insulating layer can isolate electrons while conducting ions, thereby forming ions between the positive electrode active coating and the negative electrode active coating. The sub-channel, by isolating electrons, can avoid short circuits caused by contact between the first and second conductive layers, effectively improving the lithium-ion transport rate. Lithium-ion exchange can be achieved without the need for a separator, effectively improving the space utilization of the cell and the energy density of the electrochemical device. At the same time, the projection of the negative electrode tab alignment groove in the thickness direction is controlled to cover the projection of the negative electrode tab groove in the thickness direction. There is no active material at the negative electrode tab groove, avoiding lithium deposition of lithium ions extracted from the positive electrode in the negative electrode tab groove, effectively alleviating lithium deposition in the electrochemical device, effectively improving the cycle life of the electrochemical device, and improving the self-discharge rate of the electrochemical device. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of the cell of the electrochemical device in one embodiment of this application.
[0025] Figure 2 This is a schematic diagram of the structure of the cell of the electrochemical device in another embodiment of this application.
[0026] Figure 3 This is a schematic diagram of the cell winding structure of the electrochemical device of this application.
[0027] The markings in the diagram are: 1. Insulating layer; 2. First conductive layer; 3. Second conductive layer; 4. Positive electrode active material layer; 41. Positive electrode tab groove; 42. Negative electrode tab alignment groove; 5. Negative electrode active material layer; 51. Negative electrode tab groove; 6. Positive electrode tab; 7. Negative electrode tab; 8. First insulating adhesive layer; 9. Second insulating adhesive layer; 10. Finishing adhesive tape. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0029] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.
[0030] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0031] In this application, there are no particular restrictions on the specific dispersion and mixing methods.
[0032] Unless otherwise specified, all components, raw materials, or instruments used in the embodiments and comparative examples of this application are commercially available, and the components and raw materials used in each parallel experiment are the same.
[0033] In the following description, all figures disclosed herein are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values with a lower limit RL and an upper limit RU is disclosed, any values falling within that range are specifically disclosed. Specifically, the following values within this range are specifically disclosed: R = RL + k × (RU - RL), where k is a variable ranging from 1% to 100% with a 1% increment, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values defined by the two R values as defined above are also specifically disclosed.
[0034] I. Electrochemical Device like Figure 1 As shown, this application provides an electrochemical device including a battery cell. The battery cell includes a current collector, which includes a first conductive layer 2, an insulating layer 1, and a second conductive layer 3 arranged sequentially. A positive electrode active material layer 4 is provided on the surface of the first conductive layer 2 away from the insulating layer 1, and a negative electrode active material layer 5 is provided on the surface of the second conductive layer 3 away from the insulating layer 1. The first conductive layer 2 has a plurality of first through holes 21, the second conductive layer 3 has a plurality of second through holes 32, and the insulating layer has pores for ion transport. The positive electrode active material layer 4 has a positive electrode tab groove 41 and a negative electrode tab alignment groove 42 that penetrate the positive electrode active material layer 4. The negative electrode active material layer 5 has a negative electrode tab groove 51 that penetrates the negative electrode active material layer 5. The negative electrode tab groove 51 corresponds to the negative electrode tab alignment groove 42, and the projection of the negative electrode tab alignment groove 42 in the thickness direction of the positive electrode active material layer covers the projection of the negative electrode tab groove 51 in the thickness direction of the negative electrode active material layer 5.
[0035] The electrochemical device described in this application includes a current collector, which comprises a first conductive layer 2, an insulating layer 1, and a second conductive layer 3 arranged sequentially. A positive electrode active material layer 4 is disposed on the surface of the first conductive layer 2, and a negative electrode active material layer 5 is disposed on the surface of the second conductive layer 3. A first through-hole 21 and a second through-hole 22 are respectively formed on the first conductive layer 2 and the second conductive layer 3. Thus, the first conductive layer 2 and the second conductive layer 3 can respectively function as a positive electrode current collector and a negative electrode current collector. The insulating layer 1 has pores for electrolyte entry. After the electrode is immersed in the electrolyte, the insulating layer can isolate electrons while conducting ions, thereby forming a current collector between the positive electrode active material layer 4 and the negative electrode active material layer 5. The ion-forming pathway and the isolation of electrons prevent short circuits caused by contact between the first conductive layer 2 and the second metal layer 3, effectively improving the lithium-ion transport rate. Lithium-ion exchange can be achieved without the need for a separator, effectively improving the space utilization of the battery cell and the energy density of the electrochemical device. At the same time, the projection of the negative electrode tab alignment groove in the thickness direction is controlled to cover the projection of the negative electrode tab groove in the thickness direction. There is no active material at the negative electrode tab groove 51, which avoids lithium ions extracted from the positive electrode from the negative electrode from undergoing lithium deposition in the negative electrode tab groove 51, effectively alleviating lithium deposition in the electrochemical device, effectively improving the cycle life of the electrochemical device, and improving the self-discharge rate of the electrochemical device.
[0036] In some embodiments, along the length direction of the current collector, the length of the negative electrode tab alignment groove 42 is greater than the length of the negative electrode tab groove 51; and / or Along the width direction of the current collector, the width of the negative electrode tab alignment groove 42 is greater than the width of the negative electrode plate groove.
[0037] In particular, when the length of the negative electrode tab alignment groove 42 is greater than the length of the negative electrode tab groove 51 and the width of the negative electrode tab alignment groove 42 is greater than the width of the negative electrode plate groove, the lithium deposition phenomenon at the negative electrode tab groove 51 can be better alleviated, the lithium deposition of the electrochemical device can be effectively alleviated, and the cycle life of the electrochemical device can be effectively improved.
[0038] In some embodiments, the length of the negative electrode tab alignment groove 42 is ≥7mm.
[0039] In some embodiments, the width of the negative electrode tab alignment groove 42 is 5.5~40mm.
[0040] In some embodiments, the length of the negative electrode tab groove 51 is ≥6mm.
[0041] In some embodiments, the width of the negative electrode tab groove 51 is 5~35mm.
[0042] In some embodiments, the length of the negative electrode tab alignment groove 42 is 19~23mm.
[0043] In some embodiments, the width of the negative electrode tab alignment groove 42 is 9~13mm.
[0044] In some embodiments, the length of the negative electrode tab groove 51 is 18~22mm.
[0045] In some embodiments, the width of the negative electrode tab groove 51 is 8~12mm.
[0046] In some embodiments, the positive electrode active material layer 4 includes a positive electrode active material, and the electrochemical device satisfies: h1≥0.5 D1×(1-sin5°). h1 μm is the thickness of the first conductive layer 2; D1μm is the Dv10 particle size of the positive electrode active material.
[0047] The inventors of this application have discovered that the Dv10 particle size of the positive electrode active material and the thickness of the first conductive layer 2 have a significant impact on the electrochemical performance of the electrochemical device. By controlling h1≥0.5D1×(1-sin5°), the structural stability of the battery cell can be effectively improved, preventing the positive electrode active material from being embedded in the first through-hole 21 on the first conductive layer 2 and the insulating layer 1, preventing the positive electrode active material from being squeezed and punctured, effectively improving the lithium ion insertion / extraction rate, and effectively improving the compaction density of the positive electrode active material layer 4, thereby effectively improving the energy density and cycle life of the electrochemical device.
[0048] In some embodiments, the negative electrode active material layer 5 includes a negative electrode active material, and the electrochemical device satisfies: h2≥0.5 D2×(1-sin5°). h2 μm is the thickness of the second conductive layer 3; D2 μm is the Dv10 particle size of the negative electrode active material.
[0049] The inventors of this application have discovered that the Dv10 particle size of the negative electrode active material and the thickness of the second conductive layer 3 have a significant impact on the electrochemical performance of the electrochemical device. By controlling h2≥0.5D2×(1-sin5°), the structural stability of the battery cell can be effectively improved, preventing the negative electrode active material from embedding into the second through hole 32 on the second conductive layer 3 and the insulating layer 1, effectively alleviating the volume expansion of the negative electrode active material, improving the wetting effect of the electrolyte on the negative electrode active material layer 5, and effectively improving the energy density and cycle life of the electrochemical device.
[0050] In some implementations, 1≤h1≤6, for example, it can be a range consisting of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 or any two of these values.
[0051] In some implementations, 1.5 ≤ D1 ≤ 8, for example, it can be a range consisting of 1.5, 2, 3, 4, 5, 6, 7, 8 or any two of these values; In some implementations, 1 ≤ h2 ≤ 5, for example, it can be a range consisting of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any two of these values.
[0052] In some implementations, 1.5 ≤ D2 ≤ 10.5, for example, it can be a range consisting of 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10.5 or any two of these values.
[0053] In some embodiments, the positive electrode active material layer 4 includes a positive electrode active material, and the electrochemical device satisfies: 1.5×d1<d2<0.5×D3; d1 μm is the average pore size of the insulating layer 1; d2 μm is the average aperture of the first through hole 21; D3 μm is the Dv50 particle size of the positive electrode active material.
[0054] By controlling 1.5×d1<d2<0.5×D3, the lithium-ion transport efficiency can be significantly improved, and the amount of positive electrode active material entering the first through hole 21 and the insulating layer 1 can be reduced, thus avoiding the phenomenon of hole blockage. This effectively improves the space utilization rate of the active material and effectively improves the cycle life of the electrochemical device.
[0055] In some embodiments, the negative electrode active material layer 5 includes a negative electrode active material, and the electrochemical device satisfies: 1.5×d1<d3<0.5×D4; d1 μm is the average pore size of the insulating layer 1; d3 μm is the average pore diameter of the second through hole 32; D4 μm is the Dv50 particle size of the negative electrode active material.
[0056] By controlling 1.5×d1<d3<0.5×D4, the lithium-ion transport efficiency can be significantly improved, and the entry of negative electrode active material into the first through hole 21 and insulating layer 1 can be reduced. This effectively improves the lithium deposition phenomenon on the surface of negative electrode active material layer 5 and negative electrode tab groove 51, effectively improves the space utilization of negative electrode active material, effectively improves the energy density of electrochemical device, and effectively improves the cycle life of electrochemical device.
[0057] In some implementations, 0.02≤d1≤0.3, for example, can be 0.02, 0.03, 0.05, 0.06, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3 or a range of any two of these values.
[0058] In some implementations, 0.03 ≤ d2 ≤ 5, for example, it can be 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 1.2, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any two of these values.
[0059] In some implementations, 3.5 ≤ D3 ≤ 19.5, for example, it can be a range consisting of 3.5, 4, 5, 6, 8, 10, 12, 15, 16, 18, 19, 19.5 or any two of these values.
[0060] In some implementations, 0.03 ≤ d3 ≤ 5, for example, it can be 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 1.2, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any two of these values.
[0061] In some implementations, 5 ≤ D4 ≤ 18, for example, it can be a range consisting of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or any two of these values.
[0062] In some embodiments, the spacing between adjacent first through holes 21 is 0.2 to 3.5 mm, for example, it can be 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 3.5 mm or any two of these values.
[0063] The spacing between adjacent second through holes 32 is 0.2mm to 3.5mm, for example, it can be 0.2mm, 0.5mm, 1mm, 2mm, 3mm, 3.5mm or any two of these values.
[0064] By controlling the spacing between the first through hole 21 and the second through hole 32 within this range, the lithium-ion transport efficiency can be improved, promoting the rapid insertion and extraction of lithium ions, and effectively improving the rate performance and cycle life of the electrochemical device.
[0065] In some embodiments, the first conductive layer 2 includes at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
[0066] In some embodiments, the first conductive layer 2 comprises at least one of aluminum and aluminum alloy.
[0067] In some embodiments, the aluminum content in the aluminum alloy is not less than 5 wt%.
[0068] In some embodiments, the aluminum content in the aluminum alloy is ≥80wt%.
[0069] In some embodiments, the second conductive layer 3 includes at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
[0070] In some embodiments, the second conductive layer 3 comprises at least one of copper and copper alloys.
[0071] In some embodiments, the copper content in the copper alloy is not less than 5 wt%.
[0072] In some embodiments, the copper content in the copper alloy is ≥80wt%.
[0073] like Figure 2 As shown, in some embodiments, a positive electrode tab 6 and a negative electrode tab 7 are also included, with at least a portion of the positive electrode tab 6 being accommodated in the positive electrode tab groove 41 and at least a portion of the negative electrode tab 7 being accommodated in the negative electrode tab groove 51.
[0074] In some embodiments, a first insulating adhesive layer 8 and a second insulating adhesive layer 9 are also included, with at least a portion of the first insulating adhesive layer 8 covering the positive electrode tab 6 and at least a portion of the second insulating adhesive layer 9 covering the negative electrode tab 7.
[0075] In some embodiments, the positive electrode tab 6 is connected to the groove wall of the positive electrode tab groove 41, and the connection between the positive electrode tab 6 and the groove wall of the positive electrode tab groove 41 has a welded part (also known as a solder mark). The first insulating adhesive layer 8 covers the solder mark to prevent the solder mark burrs from affecting the active material.
[0076] In some embodiments, the negative electrode tab 7 is connected to the groove wall of the negative electrode tab groove 51, and the connection between the negative electrode tab 7 and the groove wall of the negative electrode tab groove 51 has a welded part (also known as a solder mark). The second insulating adhesive layer 9 covers the solder mark to prevent the solder mark burrs from affecting the active material.
[0077] In some embodiments, the thickness of the insulating layer 1 is 2 to 15 μm, for example, it can be 2 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm or any two of these values.
[0078] In some embodiments, the porosity of the insulating layer 1 is 35% to 65%, for example, it can be 35%, 38%, 40%, 42%, 45%, 50%, 52%, 55%, 58%, 60%, 62%, 65% or any two of these values.
[0079] In some embodiments, the insulating layer 1 includes, but is not limited to, at least one of polyolefin, polyester, polyacetal, polyamide, polyethylene terephthalate, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene ether, polyphenylene sulfide, polyacrylonitrile, polyvinylidene fluoride, polyoxymethylene, polyoxymethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polytetrafluoroethylene, polysulfone, and polymethyl methacrylate.
[0080] In some embodiments, the insulating layer 1 is a polyolefin, which includes at least one of polyethylene (PE), ultra-high molecular weight polyethylene (UHMWPE), high-density polyethylene (HDPE), polypropylene (PP), polyethylene-polypropylene copolymer (PE-PP), and polyethylene-polypropylene-polyethylene copolymer.
[0081] In some embodiments, the positive electrode active material includes lithium cobalt oxide, LiNiO2, and LiNi x Mn y O2, Li 1+ z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al zThe group consisting of O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4, LiMnPO4 and combinations thereof, wherein each x is independently 0.2 to 0.9; each y is independently 0.1 to 0.45; and each z is independently 0 to 0.2.
[0082] In some embodiments, the positive electrode active material includes lithium cobalt oxide.
[0083] In some embodiments, the positive electrode active material layer 4 further includes a positive electrode binder and a positive electrode conductive agent.
[0084] In some embodiments, the positive electrode binder includes at least one selected from polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer. This application is not limited to the above materials and also includes other materials that can be used as battery positive electrode binders.
[0085] In some embodiments, the positive electrode conductive agent includes at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon tubes, carbon nanotubes, activated carbon, and mesoporous carbon. This application is not limited to the above materials, but also includes other materials that can be used as positive electrode conductive agents in batteries.
[0086] In some embodiments, the negative electrode active material includes natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesophase carbon microspheres (MCMB), Sn, SnO2, SnO, and Li4Ti5O. 12 The material is selected from at least one of the following: LTO, Si material, silicon-carbon (Si-C) composite material, silicon-nitrogen (Si-N) composite material, and silicon-oxygen (Si-O) composite material. This application is not limited to the above-mentioned materials, but also includes other materials that can be used as negative electrode active materials in batteries.
[0087] In some embodiments, the negative electrode active material includes at least one of natural graphite particles and synthetic graphite particles.
[0088] In some embodiments, the negative electrode active material layer 5 further includes a negative electrode binder and a negative electrode conductive agent.
[0089] In some embodiments, the negative electrode binder includes at least one of the following: polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, polyacrylamide, styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylic acid-acrylonitrile-acrylamide copolymer, acrylic acid-acrylonitrile-acrylate copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acryloyl rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyvinyl alcohol, polyvinyl acetate, polyepoxychloropropane, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, carboxymethyl chitosan, polyester, polyamide, polyether, polyimide, polycarboxylic acid ester, polycarboxylic acid, polyurethane, alginate, fluorinated polymer, chlorinated polymer, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropylene. This application is not limited to the above materials and also includes other materials that can be used as battery negative electrode binders.
[0090] In some embodiments, the negative electrode conductive agent includes at least one of carbon, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon tubes, carbon nanotubes, activated carbon, and mesoporous carbon. This application is not limited to the above materials, but also includes other materials that can be used as negative electrode conductive agents in batteries.
[0091] like Figure 3 As shown, in some embodiments, the current collector, the positive electrode active material layer 4, and the negative electrode active material layer 5 are wound in an arc shape to form the battery cell. The present application uses an arc-shaped winding to form the battery cell, which can avoid direct contact between the negative electrode active material layer 5 and the positive electrode active material layer 4, thus avoiding short circuits.
[0092] In some embodiments, the length of the first insulating adhesive layer 8 is equal to the length of the positive electrode tab groove ± 3.5 mm, and the thickness is 10~18 μm.
[0093] In some embodiments, the length of the second insulating adhesive layer 9 is equal to the length of the negative electrode tab groove 51 ± 3.5 mm, and the thickness is 10~18 μm.
[0094] In some embodiments, the electrochemical device further includes a finishing adhesive 10 for securing the battery cell.
[0095] The electrochemical device of this application also includes an electrolyte.
[0096] In some embodiments, the electrolyte includes at least one of a gel electrolyte, a solid electrolyte, and a liquid electrolyte.
[0097] In some embodiments, the liquid electrolyte includes a non-aqueous solvent and a lithium salt.
[0098] In some embodiments, the lithium salt includes at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB, and lithium difluoroborate.
[0099] In some embodiments, the non-aqueous solvent may be at least one of carbonate compounds, carboxylic acid ester compounds, and ether compounds.
[0100] In some embodiments, the carbonate compound includes at least one of chain carbonate compounds, cyclic carbonate compounds, and fluorocarbonate compounds.
[0101] In some embodiments, the chain carbonate compound includes diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), and combinations thereof. Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), vinyl ethylene carbonate (VEC), and combinations thereof. Examples of fluorinated carbonate compounds are at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, and trifluoromethylethylene carbonate.
[0102] In some embodiments, the carboxylic acid ester compound may be selected from at least one of methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanoic acid lactone, valerate lactone, mevalonate lactone, caprolactone, and methyl formate.
[0103] In some embodiments, the ether compound may be selected from at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
[0104] In some embodiments, the non-aqueous solvent includes at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters.
[0105] II. Electronic Devices This application also provides an electronic device, including the electrochemical device described in this application.
[0106] The application of the electrochemical device in this application is not particularly limited, and it can be used in any electronic device known in the prior art. In some embodiments, the electrochemical device includes, but is not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, android robots, etc.
[0107] III. Testing Methods In this application, the Dv10 and Dv50 particle sizes refer to the particle sizes corresponding to a cumulative volume distribution percentage of 10% and 50% for the material, respectively, which can be obtained by testing with a laser particle size analyzer.
[0108] The following uses a lithium-ion battery as an example and combines specific embodiments to illustrate the preparation of a lithium-ion battery. Those skilled in the art will understand that the preparation methods described in this application are only some examples, and any other suitable preparation methods are within the scope of this application.
[0109] Example 1 A method for preparing a lithium-ion battery includes the following steps: (1) Preparation of current collector: A PE film with an average pore size of 0.1 μm (porosity of 42%) was used as the insulating layer. An aluminum layer with a thickness of 4 μm was formed on one surface of the insulating layer by magnetron sputtering. Circular holes (1 μm in diameter and 1 mm in spacing) were drilled on the aluminum layer at equal intervals by laser drilling. A copper layer with a thickness of 3 μm was formed on the other surface of the insulating layer by magnetron sputtering. Circular holes (1 μm in diameter and 1 mm in spacing) were drilled on the copper layer at equal intervals by laser drilling to obtain the current collector.
[0110] (2) Preparation of positive electrode slurry: The active material (lithium cobalt oxide LiCoO2), conductive agent (conductive carbon black SP), conductive agent (carbon nanotubes, CNTs), and binder (polyvinylidene fluoride, PVDF) are added to NMP (N-methylpyrrolidone) solvent in a mass ratio of 96:1:1:2 and stirred thoroughly to form a positive electrode slurry with a solid content of 58%.
[0111] Preparation of negative electrode slurry: The active material (graphite), conductive agent (conductive carbon black Super P), thickener (carboxymethyl cellulose, CMC), and binder (styrene-butadiene rubber SBR) are added to deionized water solvent in a mass ratio of 96.2:0.3:0.6:2.9 and stirred thoroughly to form a negative electrode slurry with a solid content of 53%.
[0112] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed evenly in a volume ratio of 3:5:2. Then, lithium hexafluorophosphate (LiPF6) is added and stirred evenly. Then, vinylene carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propane sulfonate lactone (PS), and vinylene sulfate (DTD) are added and stirred evenly to obtain the electrolyte.
[0113] The electrolyte contains lithium hexafluorophosphate (LiPF6) at a concentration of 1 mol / L, VC at a concentration of 1 wt%, FEC at a concentration of 1 wt%, PS at a concentration of 2 wt%, and DTD at a concentration of 0.5 wt%.
[0114] (4) Preparation of lithium-ion batteries: The above-mentioned positive electrode slurry is coated on the aluminum layer side of the current collector. The positive electrode tab groove and the negative electrode tab alignment groove are created by pre-reserving the positive electrode coating or by laser cleaning after coating. After coating, pre-rolling is performed. The above-mentioned negative electrode slurry is coated on the copper layer side of the current collector after pre-rolling. The negative electrode tab groove is created by pre-reserving the negative electrode coating or by laser cleaning after coating. The electrode sheets coated with the positive and negative electrode slurries are rolled and cut. The positive and negative electrode tabs are welded into the positive electrode tab groove and the negative electrode tab groove. The electrode tab welding method is laser welding. Insulating tape is covered and attached to the surface of the positive and negative electrode tabs. The tape completely covers the electrode metal strip in the tab groove so that the burrs and solder points of the electrode metal strip will not rub against the alignment material after winding, so as to prevent the powder from falling off. The electrode sheets with the tabs welded are wound in an "arch" shape. Since the adjacent layers in the winding structure are of the same polarity, no separator is needed for physical isolation. The end of the winding core is fixed with adhesive tape. The winding core undergoes hot pressing, casing, encapsulation, baking, electrolyte injection, settling, and formation processes to produce a lithium-ion battery.
[0115] The parameters are shown in Table 1 and Table 2.
[0116] Example 2, Comparative Example 2 Example 2 and Comparative Example 2 differ from Example 1 in that the dimensions of the negative electrode tab groove and the negative electrode tab alignment groove are changed, as shown in Table 1.
[0117] Examples 3-8 The difference between Examples 3-8 and Example 1 is that h1 and D1 are changed, as shown in Table 2.
[0118] Examples 9-11 The difference between Examples 9-11 and Example 1 is that h2 and D2 are changed, as shown in Table 2.
[0119] Examples 12-17 Examples 12-17 differ from Example 1 in that d1, d2, D3, and D4 are changed, as shown in Table 2.
[0120] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not have a negative electrode tab alignment groove.
[0121] Comparative Example 3 A method for preparing a lithium-ion battery includes the following steps: (1) Preparation of positive electrode sheet: The active material (lithium cobalt oxide LiCoO2), conductive agent (conductive carbon black SP), conductive agent (carbon nanotubes, CNTs), and binder (polyvinylidene fluoride, PVDF) were added to NMP (N-methylpyrrolidone) solvent in a mass ratio of 96:1:1:2 and stirred thoroughly to form a positive electrode slurry with a solid content of 58%. The positive electrode slurry was coated on a 4μm thick aluminum foil, and the positive electrode sheet was prepared by vacuum drying and pressing. (2) Preparation of negative electrode sheet: Active material (graphite), conductive agent (conductive carbon black Super P), thickener (carboxymethyl cellulose, CMC), binder (styrene-butadiene rubber SBR) are added to deionized water solvent in a mass ratio of 96.2:0.3:0.6:2.9 and stirred thoroughly to form a negative electrode slurry with a solid content of 53%. The negative electrode slurry is coated on a 4μm thick copper foil, and the positive electrode sheet is prepared by vacuum drying and pressing. (3) Separator: A PE membrane with an average pore size of 0.1 μm is used as the separator; (4) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed evenly in a volume ratio of 3:5:2. Then, lithium hexafluorophosphate (LiPF6) is added and stirred evenly. Then, vinylene carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propane sulfonate lactone (PS), and vinylene sulfate (DTD) are added and stirred evenly to obtain the electrolyte.
[0122] The electrolyte contains lithium hexafluorophosphate (LiPF6) at a concentration of 1 mol / L, VC at a concentration of 1 wt%, FEC at a concentration of 1 wt%, PS at a concentration of 2 wt%, and DTD at a concentration of 0.5 wt%.
[0123] (5) Assembly (winding) of lithium-ion battery: The positive electrode, separator and negative electrode are stacked in sequence, so that the separator is between the positive and negative electrode to play a role in isolation. After being wound into a bare cell, it is put into the outer packaging, then baked to remove water, injected with the corresponding electrolyte, sealed, and after standing, hot and cold pressing, formation and capacity testing, the lithium-ion battery is obtained.
[0124] Table 1 Table 2 Table 3 Performance testing Cycle life: 2C constant current and constant voltage charging to 4.53V, 0.02C cutoff; 1C discharge to 3.0V; 1000 cycles above, record the cycle capacity retention rate, where cycle capacity retention rate = 100% × (C1000 / C0), C0 is the capacity of the first cycle, and C1000 is the capacity of 1000 cycles.
[0125] Energy density: (cell capacity × average voltage) / (cell length × cell width × cell thickness).
[0126] Self-discharge: After the battery cell is adjusted to a certain 30% SOC state, it is left to stand at room temperature for a period of time, and the voltage before and after storage is tested. Self-discharge = (voltage before storage - voltage after storage) / storage time.
[0127] Table 4 As can be seen from Table 4, the current collector of this application includes a first conductive layer, an insulating layer and a second conductive layer arranged sequentially. The surface of the first conductive layer is provided with a positive electrode active material layer, and the surface of the second conductive layer is provided with a negative electrode active material layer. The first conductive layer and the second conductive layer are respectively provided with a first through hole and a second through hole. This controls the projection of the negative electrode tab alignment groove in the thickness direction to cover the projection of the negative electrode tab groove in the thickness direction. There is no active material at the negative electrode tab groove, which avoids lithium ions extracted from the positive electrode from the negative electrode from undergoing lithium plating in the negative electrode tab groove. This effectively alleviates lithium plating in the electrochemical device, effectively improves the cycle life of the electrochemical device, and improves the self-discharge rate of the electrochemical device.
[0128] As can be seen from Examples 1 to 6, by controlling h1≥0.5 D1×(1-sin5°), the cycle life of the electrochemical device is further improved, and the self-discharge rate of the electrochemical device is also improved.
[0129] Comparing Example 1 with Examples 7-8, it can be seen that, under the condition that h1≥0.5 D1×(1-sin5°), by controlling 1≤h1≤6 and 1.5≤D1≤8, the cycle life of the electrochemical device is further improved and the self-discharge rate of the electrochemical device is improved.
[0130] Comparing Example 1 and Example 11, it can be seen that by controlling h2≥0.5 D2×(1-sin5°), the cycle life of the electrochemical device is further improved, and the self-discharge rate of the electrochemical device is also improved.
[0131] Comparing Examples 1 and 12-14 with Examples 15-17, it can be seen that by controlling 1.5×d1<d2<0.5×D3 and 1.5×d1<d3<0.5×D4, the cycle life of the electrochemical device is further improved, and the self-discharge rate of the electrochemical device is also improved.
[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.
Claims
1. An electrochemical device, characterized in that, The device includes a battery cell, which includes a current collector. The current collector includes a first conductive layer, an insulating layer, and a second conductive layer disposed sequentially. A positive electrode active material layer is disposed on the surface of the first conductive layer away from the insulating layer, and a negative electrode active material layer is disposed on the surface of the second conductive layer away from the insulating layer. The first conductive layer has a plurality of first through holes, the second conductive layer has a plurality of second through holes, and the insulating layer has pores for ion transport. The positive electrode active material layer has a positive electrode tab groove and a negative electrode tab alignment groove that penetrate the positive electrode active material layer. The negative electrode active material layer has a negative electrode tab groove that penetrates the negative electrode active material layer. The negative electrode tab groove corresponds to the negative electrode tab alignment groove, and the projection of the negative electrode tab alignment groove in the thickness direction of the positive electrode active material layer covers the projection of the negative electrode tab groove in the thickness direction of the negative electrode active material layer.
2. The electrochemical device according to claim 1, characterized in that, The positive electrode active material layer includes a positive electrode active material, and the electrochemical device satisfies: h1≥0.5D1×(1-sin5°). h1 μm is the thickness of the first conductive layer; D1 μm is the Dv10 particle size of the positive electrode active material; And / or, the negative electrode active material layer includes a negative electrode active material, and the electrochemical device satisfies: h2≥0.5D2×(1-sin5°). h2 μm is the thickness of the second conductive layer; D2 μm is the Dv10 particle size of the negative electrode active material.
3. The electrochemical device according to claim 2, characterized in that, Satisfy at least one of the following conditions (I) to (IV): （Ⅰ）1≤h1≤6； （Ⅱ）1.5≤D1≤8； （Ⅲ）1≤h2≤5； （Ⅳ）1.5≤D2≤10.5。 4. The electrochemical device according to claim 1, characterized in that, The positive electrode active material layer includes a positive electrode active material, and the electrochemical device satisfies: 1.5×d1<d2<0.5×D3; d1 μm is the average pore size of the insulating layer; d2 μm is the average pore diameter of the first through hole; D3 μm is the Dv50 particle size of the positive electrode active material; And / or, the negative electrode active material layer includes a negative electrode active material, and the electrochemical device satisfies: 1.5×d1<d3<0.5×D4; d1 μm is the average pore size of the insulating layer; d3 μm is the average pore diameter of the second through hole; D4μm is the Dv50 particle size of the negative electrode active material.
5. The electrochemical device according to claim 4, characterized in that, Satisfy at least one of the following conditions (V) to (IX): （Ⅴ）0.02≤d1≤0.3； （Ⅵ）0.03≤d2≤5； （Ⅶ）3.5≤D3≤19.5； （Ⅷ）0.03≤d3≤5； （Ⅸ）5≤D4≤18。 6. The electrochemical device according to claim 1, characterized in that, Satisfy the following (X)~(XVII): (X) The spacing between adjacent first through holes is 0.2~3.5mm; (XI) The spacing between adjacent second through holes is 0.2~3.5mm; (XII) The first conductive layer comprises at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy; (XIII) The second conductive layer comprises at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy.
7. The electrochemical device according to claim 1, characterized in that, It also includes a positive electrode tab and a negative electrode tab, at least a portion of the positive electrode tab is contained in the positive electrode tab groove and connected to the first conductive layer, and at least a portion of the negative electrode tab is contained in the negative electrode tab groove and connected to the second conductive layer.
8. The electrochemical device according to claim 7, characterized in that, It also includes a first insulating adhesive layer and a second insulating adhesive layer, wherein at least a portion of the first insulating adhesive layer covers the positive electrode tab and at least a portion of the second insulating adhesive layer covers the negative electrode tab.
9. The electrochemical device according to claim 1, characterized in that, The current collector, the positive electrode active material layer, and the negative electrode active material layer are wound in an arc shape to form the battery cell.
10. An electronic device, characterized in that, Includes the electrochemical device according to any one of claims 1 to 9.