Battery cell, battery device, and vehicle
By designing elliptical cells and optimizing electrode structures, the contradiction between space utilization and weight energy density in cells has been resolved, achieving high energy density and optimized cell performance, suitable for battery devices and vehicles.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- BEIJING CHEHEJIA AUTOMOBILE TECH CO LTD
- Filing Date
- 2025-04-23
- Publication Date
- 2026-05-29
AI Technical Summary
Existing battery cells are insufficient in balancing the space utilization of cylindrical steel shells and the weight energy density of square aluminum shells, making it difficult to simultaneously improve both volumetric energy density and weight energy density.
An elliptical cylindrical battery cell is designed with the ratio of its major axis to its minor axis limited to 1 < d/e ≤ 1.5. The electrode thickness gradually varies along its length. The design of the current collector and active material layers is optimized to form segments with different radial thicknesses. The cell structure is optimized by combining variable compaction and die-cutting processes.
It significantly improves the weight energy density and volumetric energy density of the battery cell, enhances charge and discharge uniformity, optimizes mechanical stress distribution, extends battery cell life, and improves heat dissipation performance.
Smart Images
Figure CN224304699U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of batteries, and in particular to a battery cell, battery device, and vehicle. Background Technology
[0002] In terms of shape, the current battery cell packaging forms are mainly divided into two categories: cylindrical cells and square aluminum shells, covering the vast majority of battery cell application scenarios; that is, two types of battery cell structures: cylindrical steel shells with wound type JR and square aluminum shells with wound type JR or stacked type JR.
[0003] Cylindrical steel-cased cells, due to their isotropic circular shape and high steel casing strength, offer relatively high space utilization. However, because the casing diameter is typically 18mm, 21mm, or 46mm, the ratio of internal active material to casing is often less than ideal, resulting in a lower gravimetric energy density compared to prismatic aluminum-cased cells. Prismatic aluminum-cased cells, on the other hand, have lower casing strength, leading to a lower volumetric energy density compared to cylindrical cells. Furthermore, the internal space needs to accommodate expansion, further reducing space utilization.
[0004] Therefore, how to make the battery cell combine the space utilization of cylindrical steel-cased cells with the weight energy density of square aluminum-cased cells is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0005] The purpose of this application is to provide a battery cell with high gravimetric energy density and volumetric energy density. Another purpose of this application is to provide a battery device and vehicle including the above-mentioned battery cell.
[0006] This application provides a battery cell, including a casing and a bare battery cell. The bare battery cell includes at least electrode plates and is an elliptical cylinder. The casing has an inner cavity, and the bare battery cell is installed in the inner cavity of the casing. The relationship between the major axis and the minor axis of the elliptical cylinder satisfies the following condition:
[0007] 1 < d / e ≤ 1.5;
[0008] In the formula, d is the length of the major axis of the elliptical cylinder, and e is the length of the minor axis of the elliptical cylinder.
[0009] Compared to prismatic cells, the elliptical cells in this application can leverage the energy density advantages of cylindrical cells. For cells with the same capacity and active material, elliptical cells have thinner casings, are lighter, and have a better distribution ratio of active material among structural components, resulting in a significant energy density advantage. Furthermore, by limiting the ratio of the major axis to the minor axis of the elliptical cell to 1 < d / e ≤ 1.5, the proportion of active material within the cell casing can be maximized within a high margin of space design, thereby increasing the gravimetric energy density.
[0010] In one example, along the length direction of the electrode, the electrode includes at least one segment, each segment having a first end and a second end arranged along the length direction, and the radial thickness of the electrode gradually increases along the direction from the first end to the second end.
[0011] In one example, the radial thickness of the first end and the radial thickness of the second end in each segment satisfy the following formula:
[0012] 2a>b>a;
[0013] In the formula, a represents the radial thickness of the first end, and b represents the radial thickness of the second end.
[0014] In one example, the electrode includes a current collector and an active material layer, the active material layer being attached to a portion of the surface of the current collector, a portion of the current collector extending axially out of the active material layer to form an electrode tab, and the radial thickness of the active material layer in each segment gradually increasing along the direction from the first end to the second end.
[0015] In one example, the radial thickness of the current collector is the same in each segment along the direction from the first end to the second end.
[0016] In one example, the radial thickness of the current collector gradually increases in each segment along the direction from the first end to the second end.
[0017] In one example, along the length direction, the segment includes a plurality of spaced sub-units, each sub-unit including a main body and a tab extending axially outward from one side of the main body, wherein the sum of the resistance value of the main body and the resistance value of the tab in the sub-unit is within a preset value range.
[0018] In one example, the tabs in the sub-units protrude from the main body by the same size, and along the length direction, the longer the tabs in each segment are, the further away from the first end they are.
[0019] This application also provides a battery device, including:
[0020] The battery housing has a receiving cavity;
[0021] At least one of the above-mentioned battery cells, wherein the battery cell is located in the receiving cavity of the battery housing.
[0022] This application also provides a vehicle, including a vehicle body and the battery device described above, wherein the battery device is mounted on the vehicle body.
[0023] Both the battery device and the vehicle of this application include the aforementioned battery cell, and therefore both the vehicle and the battery device also have the aforementioned technical effects of the battery cell. Attached Figure Description
[0024] Figure 1 This is a schematic cross-sectional view of a battery cell in one embodiment of this application;
[0025] Figure 2 for Figure 1 A schematic diagram of the bare cell structure of the battery cell shown;
[0026] Figure 3 This is a schematic diagram of the structure of a segment in an electrode sheet in one embodiment of this application;
[0027] Figure 4 for Figure 3 A bottom view of the segment shown;
[0028] Figure 5 for Figure 3 A schematic diagram of a portion of the segment shown;
[0029] Figure 6 for Figure 5 Sectional view of AA.
[0030] in, Figures 1 to 6 The one-to-one correspondence between the reference numerals and component names in the attached drawings is as follows:
[0031] 1. Outer casing; 2. Bare cell; 21. Electrode; 21A. First terminal; 21B. Second terminal; 210. Tab; 2-1. First sub-unit; 2-1A. First main body; 210A. First tab; 2-2. Second sub-unit; 2-2A. First main body; 210B. Second tab; 2-3. Third sub-unit; 2-3A. Third main body; 210C. Third tab; 211. Current collector; 212. Active material layer. Detailed Implementation
[0032] Please refer to Figures 1 to 6 , Figure 1 This is a schematic cross-sectional view of a battery cell in one embodiment of this application; Figure 2 for Figure 1 A schematic diagram of the bare cell structure of the battery cell shown; Figure 3This is a schematic diagram of a segment structure of an electrode sheet in one embodiment of this application; Figure 4 for Figure 3 A bottom view of the segment shown; Figure 5 for Figure 3 A schematic diagram of a portion of the segment shown; Figure 6 for Figure 5 Sectional view AA, in which Figure 5 This is a schematic diagram of the sub-unit after cold pressing. Figure 6 This is a schematic diagram of the structure after the tabs are die-cut.
[0033] In this embodiment, the battery cell includes components such as a casing and a bare battery cell. In one example, the casing may include a housing with an opening and a top cover installed at the opening, with the housing and top cover forming an inner cavity. The casing can be made of aluminum or other metals, providing high strength. The bare battery cell includes electrodes and a separator, with the electrodes specifically divided into positive and negative electrodes, and the separator located between the positive and negative electrodes. When winding the bare battery cell, the negative electrode, separator, and positive electrode are stacked together in sequence and then wound to form the bare battery cell. Of course, the winding of the positive electrode, negative electrode, and separator usually requires the aid of tooling equipment.
[0034] In this embodiment, the bare battery cell 2 is installed inside the cavity of the outer casing 1 and is used to store electrical energy. At least one tab 210 is provided on both the positive and negative electrode plates, see [reference]. Figure 4 The number of tabs 210 can be determined according to the number of turns of the bare cell 2. The tab on the positive electrode is called the positive tab, and the tab on the negative electrode is called the negative tab. The positive tab is electrically connected to the positive terminal through the first connector, and the negative tab is electrically connected to the negative terminal through the second connector. Both the positive and negative terminals are partially located outside the outer casing 1. The portion of the positive terminal located outside the outer casing 1 forms the positive terminal of the cell, and the portion of the negative terminal located outside the outer casing 1 forms the negative terminal. Although the terminals, the first connector, the second connector, and other components are not shown in this document, this does not impede the understanding of those skilled in the art of the above description.
[0035] The positive and negative terminals can be located on the same side of the outer casing 1 or on different sides of the outer casing 1, for example, the positive and negative terminals can be located on opposite sides of the outer casing 1.
[0036] In this embodiment, the bare cell 2 is an elliptical cylinder. The axis around which the electrode 21 is wound is defined as the winding axis, and the cross-section of the bare cell 2 perpendicular to the winding axis is elliptical. The bare cell 2 is installed in the inner cavity of the outer casing 1, which is also an elliptical cylinder. For simplicity in molding, the outer contour of the outer casing 1 can also be an elliptical cylinder.
[0037] In this embodiment, the length of the major axis of the elliptical cylinder is d, and the length of the minor axis is e, where d / e > 1 and d / e ≤ 1.5. For example, the value of d / e can be 1.1, 1.2, 1.3, 1.4, or 1.5, etc. Of course, the value of d / e can be any value in the interval (1, 1.5), and is not limited to the specific values described above.
[0038] Compared to prismatic cells, the elliptical cells in this application can leverage the energy density advantages of cylindrical cells. For cells with the same capacity and active material, elliptical cells have thinner casings, are lighter, and have a better distribution ratio of active material among structural components, resulting in a significant energy density advantage. Furthermore, this application limits the ratio of the major axis to the minor axis of the elliptical cell to 1 < d / e ≤ 1.5, which maximizes the proportion of active material in the cell's inner casing within a high margin of space design, thereby increasing the gravimetric energy density.
[0039] Group margin refers to the percentage of space occupied by the bare cell 2 within the inner cavity of the casing 1.
[0040] Please combine Figure 1 and Figure 3 Understanding, among which Figure 3 In this embodiment, 'a' represents the radial thickness of the first end 21A, 'b' represents the radial thickness of the second end 21B, and 'c' represents the length of the electrode 21. In this embodiment, the electrode 21 includes at least one segment. The electrode 21 may include a segment, which can be a part of the electrode 21 or the entire electrode 21. The electrode 21 may also include two or more segments, arranged along its length. Adjacent segments can be directly connected, or indirectly connected through intermediate segments. Each segment includes a first end 21A and a second end 21B, arranged along its length. Along the direction from the first end 21A to the second end 21B, the radial thickness of the electrode 21 in each segment gradually increases. Please refer to... Figure 1 The so-called radial thickness refers to the thickness in the radial direction. Figure 1 The thickness of the battery cell shown is along the direction from the center O of the ellipse to the outer peripheral wall in the cross-section.
[0041] For example, the second end 21B of the segment can correspond to the minor axis of the elliptical body, and the first end 21A of the segment can correspond to the major axis of the elliptical body.
[0042] Both the positive and negative electrodes follow the variation pattern of electrode 21 described above, resulting in a radial thickness gradient along the length of the electrodes. This offers the following advantages: 1. Optimized weight and volume ratios in different regions of electrode 21 improve charge-discharge uniformity and enhance rate performance; 2. Optimized local heat dissipation; thinner regions reduce current density and heat generation, contributing to overall heat dissipation uniformity and extending lifespan; 3. Improved mechanical stress distribution across regions of varying thickness; reduced stress in thinner electrode areas mitigates electrode structure damage during charge-discharge processes.
[0043] In one example, the radial thickness of the first end 21A and the radial thickness of the second end 21B in each segment satisfy the following formula: 2a>b>a, which can balance the gravimetric energy density and volumetric energy density as much as possible. The elliptical shape of the cell is achieved by varying the thickness of the electrode 21 along its length.
[0044] Combination Figure 6 In one specific example, the electrode 21 includes a current collector 211 and an active material layer 212. The current collector 211 is a metal with good conductivity, such as aluminum, nickel, or nickel-plated copper. The active material layer 212 is attached to a portion of the surface of the current collector 211. The active material layer 212 can be an inorganic conductive reinforcing material, a nano-reinforcing material, or a rare element. The active material layer 212 can be bonded to the current collector 211 by coating or spraying. The active material layer 212 covers a portion of the current collector 211, and a localized portion of the current collector 211 extends axially from the active material layer 212 to form an electrode tab.
[0045] In this embodiment, along the direction from the first end 21A to the second end 21B, the radial thickness of the active material layer 212 in each segment gradually increases. That is, the active material layer 212 in each segment has a different radial thickness along the length of the electrode 21. By using a compaction process, different locations of the active material layer 212 achieve different compaction densities. In other words, by designing a variable compaction electrode, the radial thickness of the electrode 21 along its length is varied, resulting in an elliptical battery cell morphology. This molding process is relatively simple. For example, by controlling the thickness of the electrode 21, the compaction density range is limited to vary from 1.4 to 1.8.
[0046] In this embodiment, the radial thickness of the current collector 211 in each segment can also be different along the length of the electrode 21. For example, the radial thickness of the current collector 211 can gradually increase along the direction from the first end 21A to the second end 21B. In this way, by controlling the radial thickness of both the active material layer 212 and the current collector 211, the thickness variation can be achieved relatively easily.
[0047] Of course, the radial thickness of the current collector 211 in each segment can be the same along the direction from the first end 21A to the second end 21B. For example, the electrode 21 has a current collector 211 with the same radial thickness. The current collector 211 has a simple structure, which greatly reduces the forming process of the electrode 21.
[0048] In the above embodiments, each segment includes several spaced sub-units along its length. Each sub-unit includes a main body and a tab extending axially outward from one side of the main body. The sum of the resistance values of the main body and the tabs in the sub-unit is within a preset range. To better understand the above, this application combines... Figure 4 , Figure 5 and Figure 6 Please provide an explanation, in which Figure 4 In this context, f represents the dimension of electrode 21 in the height direction. Figure 4 and Figure 5 The viewing directions of electrode 21 are the same. Figure 5 and Figure 6 The diagram shows three sub-units on a segment: a first sub-unit 2-1, a second sub-unit 2-2, and a third sub-unit 2-3, arranged sequentially along the direction from the first end 21A to the second end 21B. The first sub-unit 2-1 includes a first main body 2-1A and a first tab 210A; the second sub-unit 2-2 includes a second main body 2-2A and a second tab 210B; and the third sub-unit 2-3 includes a third main body 2-3A and a third tab 210C. The resistance value of the first main body 2-1A is Re1, the resistance value of the first tab 210A is Rtab1, the resistance value of the second main body 2-2A is Re2, the resistance value of the second tab 210B is Rtab2, the resistance value of the third main body 2-3A is Re3, and the resistance value of the third tab 210C is Rtab3. In one example, Re1 + Rtab1 = Re2 + Rtab2 = Re3 + Rtab3. Of course, the three can also be approximately equal, as long as the difference falls within a predetermined range.
[0049] In this way, the current density distribution within the battery cell is matched to meet the most suitable charging conditions.
[0050] In the above embodiments, the dimensions of the tabs protruding from the main body in the sub-units are the same. Along the length direction, the farther away from the first end 21A in each segment, the longer the tab in the sub-unit. That is, the longer the tab is at the position with the greater thickness in the segment. As shown in the figure, the lengths L1 of the first tab 210A, L2 of the second tab 210B, and L3 of the third tab 210C are in the order L1 > L2 > L3. The heights of the first tab 210A, the second tab 210B, and the third tab 210C can all be H.
[0051] The tabs in the above embodiments can be achieved through a die-cutting process. Different die-cutting internal resistances of different sub-units are designed, and the active material layer is combined with the variable compaction design to jointly optimize the internal resistance distribution of the bare cell, so as to achieve the consistency of the internal resistance of the sub-units. That is, different die-cutting internal resistances are designed under different compaction sub-units to ensure the consistency of the internal resistance of the cell to the greatest extent, and to meet the consistency of the sum of the current collector and the electrode internal resistance in all sub-units. The current collector 211 structure is relatively simple.
[0052] The battery cells in this application embodiment can be used individually or multiple cells can be integrated to form a battery device. This battery device can be applied to vehicles or other electrical equipment, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, electric vehicles, ships, and spacecraft. For example, spacecraft include aircraft, rockets, space shuttles, and spacecraft. The battery device primarily provides electrical energy to vehicles and other electrical equipment. This application uses the application of a battery device in a vehicle as an example to further describe the technical solution and its effects.
[0053] In this embodiment, the vehicle can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The vehicle includes a body, and a battery device is mounted on the body. The battery device can be located at the bottom, front, or rear of the vehicle. The battery device can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. In some embodiments of this application, the battery device can not only serve as the vehicle's operating power source but also as its driving power source, replacing or partially replacing gasoline or natural gas to provide driving power for the vehicle.
[0054] The vehicle and battery device of this application both include the aforementioned battery cell, therefore the vehicle and battery device also have the aforementioned technical effects of the battery cell.
[0055] In the description of embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.
[0056] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0057] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.
Claims
1. A battery cell, characterized in that, The device includes a housing (1) and a bare battery cell (2). The bare battery cell (2) includes at least an electrode (21). The bare battery cell (2) is an elliptical cylinder. The housing (1) has an inner cavity. The bare battery cell (2) is installed in the inner cavity of the housing (1). The relationship between the major axis and the minor axis of the elliptical cylinder satisfies the following condition: 1 < d / e ≤ 1.5; In the formula, d is the length of the major axis of the elliptical cylinder, and e is the length of the minor axis of the elliptical cylinder.
2. The battery cell according to claim 1, characterized in that, Along the length direction of the electrode (21), the electrode (21) includes at least one segment, each segment having a first end (21A) and a second end (21B) arranged along the length direction, and the radial thickness of the electrode (21) gradually increases along the direction from the first end (21A) to the second end (21B).
3. The battery cell according to claim 2, characterized in that, The radial thickness of the first end (21A) and the radial thickness of the second end (21B) in each segment satisfy the following formula: 2a>b>a; In the formula, a is the radial thickness of the first end (21A) and b is the radial thickness of the second end (21B).
4. The battery cell according to claim 2, characterized in that, The electrode (21) includes a current collector (211) and an active material layer (212). The active material layer (212) is attached to a portion of the surface of the current collector (211). A portion of the current collector (211) extends the active material layer (212) along the axial direction of the elliptical cylinder to form an electrode tab (210). The radial thickness of the active material layer (212) in each segment gradually increases along the direction from the first end (21A) to the second end (21B).
5. The battery cell according to claim 4, characterized in that, Along the direction from the first end (21A) to the second end (21B), the radial thickness of the current collector (211) in each segment is the same.
6. The battery cell according to claim 4, characterized in that, Along the direction from the first end (21A) to the second end (21B), the radial thickness of the current collector (211) in each segment gradually increases.
7. The battery cell according to any one of claims 2 to 6, characterized in that, Along the length direction, the segment includes a plurality of spaced sub-units, each sub-unit including a main body and a tab (210) extending outward along the axial direction from one side of the main body. The sum of the resistance value of the main body and the resistance value of the tab (210) in the sub-unit is within a preset value range.
8. The battery cell according to claim 7, characterized in that, The tabs (210) in the subunit protrude from the main body by the same size. Along the length direction, the farther away from the first end (21A) in each segment, the longer the tabs (210) in the subunit.
9. A battery device, characterized in that, include: The battery housing has a receiving cavity; At least one battery cell according to any one of claims 1 to 8, wherein the battery cell is located in the receiving cavity of the battery housing.
10. A vehicle, characterized in that, It includes a vehicle body and the battery device as described in claim 9, wherein the battery device is mounted on the vehicle body.