Pole piece assembly, battery monomer and battery pack
By setting a partially covered safety coating on the positive electrode of the lithium-ion battery and setting it in a staggered manner, the problem of capacity and rate performance degradation caused by the safety coating is solved, and the safety and stability of the battery are enhanced.
Patent Information
- Application Number
- CN202422799699.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2034-11-15
AI Technical Summary
In the prior art, a safety coating is fully applied between the active material layer and the current collector of the positive electrode of a lithium-ion battery, resulting in reduced battery capacity and rate performance, and a risk of thermal runaway during mechanical abuse.
A first coating area and a second coating area are set on the positive electrode sheet. The safety coating only covers part of the current collector, with a projected area of 50% to 100% of the active material area. They are staggered to increase the film resistance of the electrode and reduce the risk of short-circuit current and thermal runaway.
The battery's safety performance is improved and the risk of thermal runaway during mechanical abuse is reduced, while maintaining the battery's capacity and rate performance.
Smart Images
Figure CN223487068U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery technology, and more specifically, to an electrode assembly, a battery cell, and a battery pack. Background Technology
[0002] As the primary power source for new energy vehicles and many electronic devices, the energy density of secondary batteries is a crucial indicator of battery performance. Higher energy density means a higher energy storage capacity per unit weight, resulting in longer battery life or driving range. In recent years, with the increasing energy density of secondary batteries, battery safety has become a growing concern. Mechanical abuse (especially punctures and impacts from heavy objects) can cause internal short circuits in secondary batteries, generating significant current and heat, leading to thermal runaway, and ultimately, fire and explosion, causing personal injury and property damage. Utility Model Content
[0003] Currently, the common practice in the field is to improve battery safety performance by applying a safety coating. For example, a safety coating is typically applied to the entire surface between the active material layer and the current collector of the positive electrode in a lithium-ion battery. While this improves battery safety, it not only reduces battery capacity but also negatively impacts the rate performance of the lithium-ion battery. The main objective of this invention is to provide an electrode assembly, a battery cell, and a battery pack to solve the problem of reduced battery capacity and rate performance caused by applying a safety coating to the entire surface between the active material layer and the current collector of the positive electrode in existing lithium-ion batteries.
[0004] To achieve the above objectives, this utility model provides an electrode assembly, a battery cell, and a battery pack. The electrode assembly includes multiple positive electrode sheets and multiple negative electrode sheets, which are alternately arranged along the thickness direction of the positive electrode sheets. Each positive electrode sheet includes: a current collector, on which an active material region is disposed, the active material region including at least one first coating region and at least one second coating region; the first coating region contains only an active material layer; the second coating region contains an active material layer and a safety coating, the safety coating being disposed between the active material layer and the current collector; wherein, in the electrode assembly, the sum of the projected areas of each safety coating on its respective current collector is 50% to 100% of the area of the active material region of any positive electrode sheet.
[0005] In some embodiments, the safety coatings on adjacent positive electrode sheets are staggered along the thickness direction of the positive electrode sheet.
[0006] In some embodiments, a single positive electrode includes a second coating region; or, a single positive electrode includes multiple second coating regions arranged at intervals along the length or width of the current collector.
[0007] In some embodiments, the safety coating is a solid electrolyte coating and / or a ceramic coating.
[0008] In some embodiments, the thickness of the safety coating is from 0.5 μm to 10 μm.
[0009] In some embodiments, the safety coating is composed of particulate matter with a particle size D50 of 80 nm to 500 nm.
[0010] In some embodiments, the thickness of the coating in the first coating area is equal to the thickness of the coating in the second coating area. According to another aspect of the present invention, a battery cell is provided. The battery cell includes a housing and the aforementioned electrode assembly located within the housing.
[0011] According to another aspect of the present invention, a battery pack is provided, including the aforementioned battery cells.
[0012] By applying the technical solution of this utility model, a first coating area and a second coating area are provided on each positive electrode sheet. The safety coating of the second coating area can contact a portion of the current collector surface, while the active material layer of the first coating area contacts the remaining current collector surface. The projected area of the safety coating of each positive electrode sheet on the current collector is relatively small. Thus, when multiple positive electrode sheets are stacked in the thickness direction, the total projected area of the safety coatings of the multiple positive electrode sheets on the current collector is 50% to 100% of the projected area of the active material layer of one positive electrode sheet on the current collector. Compared with the prior art where a safety coating is fully applied between the active material layer and the current collector of the positive electrode sheet in a lithium-ion battery, in this embodiment, by coating a portion of the current collector of each positive electrode sheet with an insulating safety coating, the overall electrode film resistance of the positive electrode sheet is increased, the current generated when the battery is subjected to puncture or internal short circuit is reduced, and the risk of thermal runaway is lowered. At the same time, since the safety coating is located between the current collector and the active material layer and does not completely cover the current collector, the adverse effects of the safety coating on the battery capacity and rate performance are effectively reduced. Attached Figure Description
[0013] The accompanying drawings are provided to further illustrate the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.
[0014] Figure 1 A schematic diagram of the structure of an embodiment of the electrode assembly of this utility model is shown;
[0015] Figure 2 A schematic diagram of the structure of the positive electrode in an embodiment of the electrode assembly is shown;
[0016] Figure 3A schematic diagram of the structure of the positive electrode in the electrode assembly according to Embodiment 2 is shown;
[0017] Figure 4 This diagram illustrates a fabrication process of the positive electrode in an electrode assembly.
[0018] Figure 5 Show Figure 4 Schematic diagrams of the structures of two positive electrodes during the preparation of electrode components;
[0019] Figure 6 Show Figure 5 Front view of two positive electrodes in the electrode assembly.
[0020] The above figures include the following reference numerals:
[0021] 10. Positive electrode; 20. Negative electrode; 11. Current collector; 12. Active material layer; 13. Safety coating; 14. Second coating area; 15. First coating area; 16. Separator. Detailed Implementation
[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0023] It should be noted that the thickness direction and length direction are as follows: Figure 1 As shown, the width direction is as follows Figure 4 As shown.
[0024] like Figures 1 to 3 As shown, an embodiment of this utility model provides an electrode assembly. The electrode assembly includes multiple positive electrode sheets 10 and multiple negative electrode sheets 20, which are alternately arranged along the thickness direction of the positive electrode sheets 10. Each positive electrode sheet 10 includes: a current collector 11, on which an active material region is disposed, the active material region including at least one first coating region 15 and at least one second coating region 14; the first coating region 15 is provided with only an active material layer 12; the second coating region 14 is provided with an active material layer 12 and a safety coating 13, the safety coating 13 being disposed between the active material layer 12 and the current collector 11; wherein, in the electrode assembly, the sum of the projected areas of each safety coating 13 on its respective current collector 11 is 50% to 100% of the area of the active material region of any positive electrode sheet 10. In some embodiments, the sum of the projected areas of each safety coating 13 on its respective current collector 11 is 60%-90% or 65%-80% of the active material area of any positive electrode 10.
[0025] In the above technical solution, by providing a first coating area 15 and a second coating area 14 on each positive electrode 10, the safety coating 13 of the second coating area 14 can contact a portion of the surface of the current collector 11, while the active material layer 12 of the first coating area 15 contacts the remaining surface of the current collector 11. The projected area of the safety coating 13 of each positive electrode 10 on the current collector 11 is relatively small. Thus, when multiple positive electrode 10s are stacked in the thickness direction, the total projected area of the safety coating 13 of the multiple positive electrode 10s on the current collector 11 is 50% of the area of the active material region of one positive electrode 10. From 100% to 100%, compared to the prior art where a safety coating is fully applied between the active material layer 12 and the current collector 11 of the positive electrode 10 of a lithium-ion battery, in this embodiment, by coating a portion of the current collector 11 of each positive electrode 10 with an insulating safety coating 13, the overall electrode film resistance of the positive electrode 10 is increased, the current generated when the battery is subjected to puncture or internal short circuit is reduced, and the risk of thermal runaway is reduced; at the same time, since the safety coating is disposed between the current collector and the active material layer and does not completely cover the current collector, the adverse effects of the safety coating on the battery capacity and rate performance are effectively reduced.
[0026] like Figures 1 to 3 As shown in the embodiment of this utility model, the safety coating 13 on adjacent positive electrode sheets 10 is staggered in the thickness direction.
[0027] With the above settings, the projection portions of the safety coatings 13 on adjacent positive electrode plates 10 in the thickness direction can overlap or not overlap, thereby increasing the projection area of the safety coatings 13 on the current collector 11 of multiple positive electrode plates 10.
[0028] like Figures 1 to 3 As shown, in the embodiments of this utility model, the safety coating 13 is a solid electrolyte coating and / or a ceramic coating.
[0029] Through the above-mentioned settings, the safety coating 13 can reduce the risk of thermal runaway in the event of overheating or mechanical damage to the battery, thereby improving the safety performance of the battery.
[0030] Specifically, in the embodiments of this utility model, the solid electrolyte coating includes an oxide solid electrolyte coating and a sulfide solid electrolyte coating. The oxide solid electrolyte coating includes a NASCION type solid electrolyte coating, a LISCION type solid electrolyte coating, a garnet type solid electrolyte coating, and a perovskite type solid electrolyte coating. Specifically, the oxide solid electrolyte coating includes an LLZO (lithium lanthanum zirconium oxide) coating, an LATP (lithium aluminum titanium phosphate) coating, and a LAG (lithium aluminum titanium phosphate) coating. The ceramic coating includes an Al2O3 coating, a SiO2 coating, a ZrO2 coating, a TiO2 coating, a γ-AlOOH coating, a BaTiO3 coating, and a Mg(OH)2 coating.
[0031] like Figures 1 to 3 As shown, in the embodiments of this utility model, the thickness of the safety coating 13 is 0.5 μm to 10 μm.
[0032] By adopting the above settings, it is possible to avoid the effect of increasing the internal resistance of the electrode and reducing the short-circuit current due to the excessive thickness of the safety coating 13, and also to avoid the reduction of the proportion of the active material layer 12 in the positive electrode 10 and the decrease of energy density due to the excessive thickness of the safety coating 13.
[0033] In some embodiments, the thickness of the safety coating 13 is 1 μm to 9 μm, or 2 μm to 8 μm, or 3 μm to 7 μm, or 4 μm to 6 μm.
[0034] like Figures 1 to 3 As shown in the embodiment of this utility model, the safety coating 13 is composed of particulate matter with a particle size D50 of 80nm to 500nm.
[0035] In some embodiments, the particle size D50 of the particulate matter is 100 nm to 450 nm, or 120 nm to 400 nm, or 150 nm to 350 nm, or 200 nm to 300 nm.
[0036] It should be noted that in the embodiments of this utility model, particle size D50 refers to the particle size of the particulate matter.
[0037] like Figures 1 to 3 As shown, in an embodiment of this utility model, the thickness of the inner coating of the first coating area 15 is equal to the thickness of the inner coating of the second coating area 14.
[0038] With the above arrangement, the surfaces of the first coating area 15 and the second coating area 14 facing away from the current collector 11 can be made flush, thereby making the upper and lower surfaces of the positive electrode 10 flat. In this way, the diaphragm 16 between the positive electrode 10 and the negative electrode 20 can be avoided from being punctured or worn.
[0039] Specifically, if Figure 1 As shown in the embodiment of this utility model, the negative electrode sheet 20 includes a negative electrode current collector, and along the thickness direction, a negative electrode active material layer is coated on both sides of the negative electrode current collector.
[0040] Specifically, in the embodiments of this utility model, a separator 16 is provided between the positive electrode 10 and the negative electrode 20, and the positive electrode 10, the negative electrode 20 and the separator 16 are stacked in a Z-shape.
[0041] Example 1
[0042] like Figure 2 As shown, a single positive electrode 10 includes a second coating region 14.
[0043] With the above settings, the safety coating 13 of the second coating area 14 can be continuously and centrally distributed on the surface of the current collector 11, making the coating simple and easy to operate.
[0044] Specifically, in Embodiment 1 of this utility model, the safety coating 13 is a regular shape, such as a rectangle or a square; the safety coating 13 can also be an irregular shape, as long as the sum of the projected areas of the safety coating 13 of each positive electrode 10 on its current collector 11 is 50% to 100% of the area of the active material region of any positive electrode 10.
[0045] Example 2
[0046] The difference between Embodiment 2 and Embodiment 1 is that a single positive electrode 10 includes multiple second coating regions 14. Specifically, as shown... Figure 3 As shown, a single positive electrode 10 includes a plurality of second coating regions 14, which are spaced apart in the length or width direction of the current collector 11.
[0047] With the above settings, the safety coating 13 of the second coating area 14 can be dispersed on the surface of the current collector 11, reducing the adverse effects on the rate performance of the electrode assembly.
[0048] It should be noted that in Embodiment 2 of this utility model, a first coating area 15 is provided between two adjacent second coating areas 14.
[0049] Specifically, the sum of the projected areas of the safety coating 13 on its current collector 11 is 50% to 100% of the active material area of any positive electrode 10.
[0050] A method for preparing the positive electrode 10 in Embodiment 2 of this utility model is as follows: Figure 4 As shown, the current collector 11 has tab regions at both ends in the width direction. Between the two tab regions are multiple first coating regions 15 and multiple second coating regions 14. Along the width direction, the first coating regions 15 and second coating regions 14 are adjacent and alternately arranged. The tab region at one end of the current collector 11 is connected to the first coating region 15, and the tab region at the other end is connected to the second coating region 14. A safety coating 13 is applied to the second coating region 14 of the current collector 11. After the safety coating 13 dries, an active material layer 12 is applied to the current collector 11. Then, the current collector 11 is cut to obtain two types of positive electrode sheets 10 (e.g., ...). Figure 5 As shown, Figure 5 This is a perspective view, showing the safety coating on the current collector surface through the active material layer on the electrode surface. Assembling the two positive electrodes into an electrode assembly results in a structure where the safety coating 13 is misaligned in the thickness direction (e.g., ...). Figure 6 (As shown).
[0051] It should be noted that, in the embodiments of this utility model, such as Figure 1 As shown, the electrode assembly includes three positive electrode sheets 10 arranged sequentially along the thickness direction of the positive electrode sheet 10. For ease of explanation, the three positive electrode sheets 10 are referred to as positive electrode sheet N1, positive electrode sheet N2, and positive electrode sheet N3, respectively. The active material layer 12 can be double-sided coated on the current collector 11 of the positive electrode sheet 10, and the safety coating 13 can also be double-sided coated on the current collector 11 of the positive electrode sheet 10, for example... Figure 1 The safety coating 13 can also be applied to only one side of the current collector 11 of the positive electrode 10, for example, the first positive electrode N1 and the second positive electrode N2. Figure 1 The third positive electrode N3. If both sides of the current collector 11 are provided with active material layers 12, the projections of the safety coating 13 on the current collector 11 on the current collector 11 can completely overlap, for example, the first positive electrode N1; the active material layers 12 on both sides of the current collector 11 can also be arranged with staggered projections, for example, the second positive electrode N2.
[0052] This invention provides a battery cell. The battery cell includes a housing and the aforementioned electrode assembly located within the housing. Specifically, in embodiments of this invention, the battery cell can be one of a liquid battery, a semi-solid battery, and a solid battery.
[0053] Specifically, in the embodiments of this utility model, the preparation process of the electrode assembly and the battery cell (containing electrolyte) is as follows:
[0054] S1, Preparation of safety coating: Take 330 g of LATP (lithium aluminum titanium phosphate) with a particle size of 300 nm and 110 g of PVDF (polyvinylidene fluoride), disperse them in 1200 g of NMP (N-methylpyrrolidone) solution, and after complete dispersion, apply the coating in an intermittent stripe pattern. The coating thickness is 3 micrometers, and then dry it.
[0055] S2, Preparation of the active coating: Weigh 3000g of ternary 811 material, 28.7g of SP (conductive carbon black), 16g of PVDF (polyvinylidene fluoride), and 790g of carbon nanotube conductive agent, add them to a mixing tank and mix thoroughly to obtain an active material slurry. Coat the active material slurry evenly and continuously onto the striped safety coating to a thickness of 200 micrometers. After baking, rolling, and cutting, obtain 10 positive electrode sheets.
[0056] S3, Preparation of negative electrode 20: Weigh 3000g of graphite, 31.5g of SP, 47.3g of CMC (sodium carboxymethyl cellulose), and 181.2g of SBR (styrene-butadiene rubber), add them to a mixing tank and mix evenly to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on the upper and lower surfaces of the copper foil, and obtain the negative electrode 20 by baking, rolling and cutting.
[0057] S4, Prepare the electrode assembly: Stack the positive electrode 10, the separator 16 and the negative electrode 20 in a Z-shape to obtain the electrode assembly.
[0058] Furthermore, the prepared battery cell assembly is packaged in an aluminum-plastic bag, placed in a vacuum drying oven, and vacuum-baked at 80°C for 12 hours. Then, electrolyte is injected, and the battery is allowed to stand and soak at room temperature for 48 hours before formation, molding, and capacity testing are performed to obtain a single battery cell.
[0059] The aforementioned battery cells possess all the advantages of the aforementioned electrode assemblies, which will not be elaborated upon here.
[0060] An embodiment of this utility model provides a battery pack including the aforementioned battery cells. The battery pack possesses all the advantages of the aforementioned battery cells, which will not be elaborated further here.
[0061] From the above description, it can be seen that the above embodiments of this utility model achieve the following technical effects: By setting a first coating area and a second coating area on each positive electrode sheet, the safety coating of the second coating area can contact the surface of part of the current collector, and the active material layer of the first coating area contacts the surface of the remaining current collector. The projected area of the safety coating on the current collector of each positive electrode sheet is small. Thus, when multiple positive electrode sheets are stacked in the thickness direction, the total projected area of the safety coating on the current collector is 50% to 100% of the area of the active material region of one positive electrode sheet. Compared with the prior art of fully coating the active material layer and the current collector of the positive electrode sheet of the lithium-ion battery, in this embodiment, by coating a safety coating with insulating function on part of the current collector of each positive electrode sheet, the overall electrode film resistance of the positive electrode sheet is increased, the current generated when the battery is subjected to puncture or internal short circuit is reduced, and the risk of thermal runaway is reduced. At the same time, since the safety coating is set between the current collector and the active material layer and does not completely cover the current collector, the adverse effects of the safety coating on the battery capacity and rate performance are effectively reduced.
[0062] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. An electrode assembly, characterized in that, It includes multiple positive electrode plates (10) and multiple negative electrode plates (20), the positive electrode plates (10) and the negative electrode plates (20) being alternately arranged along the thickness direction of the positive electrode plates (10), each of the positive electrode plates (10) comprising: A current collector (11) is provided with an active material region, the active material region including at least one first coating region (15) and at least one second coating region (14); Only an active material layer (12) is provided in the first coating area (15); The second coating area (14) is provided with the active material layer (12) and the safety coating (13), and the safety coating (13) is disposed between the active material layer (12) and the current collector (11); In the electrode assembly, the sum of the projected areas of each of the safety coatings (13) on the current collector (11) is 50% to 100% of the active material area of any of the positive electrode (10).
2. The electrode assembly according to claim 1, characterized in that, Along the thickness direction of the positive electrode (10), the safety coating (13) on adjacent positive electrode (10) is staggered.
3. The electrode assembly according to claim 1, characterized in that, Each of the positive electrode sheets (10) includes a second coating region (14); Alternatively, a single positive electrode (10) may include a plurality of second coating areas (14) arranged at intervals along the length or width of the current collector (11).
4. The electrode assembly according to claim 1, characterized in that, The safety coating (13) is a solid electrolyte coating and / or a ceramic coating.
5. The electrode assembly according to claim 1, characterized in that, The thickness of the safety coating (13) is 0.5 μm to 10 μm.
6. The electrode assembly according to claim 1, characterized in that, The safety coating (13) is composed of particulate matter with a particle size D50 of 80 nm to 500 nm.
7. The electrode assembly according to claim 1, characterized in that, The thickness of the coating in the first coating area (15) is equal to the thickness of the coating in the second coating area (14).
8. A single battery cell, characterized in that, It includes a housing and an electrode assembly as described in any one of claims 1 to 7 located within the housing.
9. A battery pack, characterized in that, Includes the battery cell as described in claim 8.