Batteries and electrical devices

Abstract

This application relates to the technical field of batteries, and more particularly to a battery and an electrical device. The battery includes multiple battery cells arranged sequentially in the same direction. Each battery cell includes a first battery cell and a second battery cell. The full-charge expansion force of the first battery cell is greater than that of the second battery cell, and the first and second battery cells are configured such that, when the battery has been cycled 500 times or more, the difference in full-charge expansion force between the first and second battery cells is greater than or equal to 400N. In the battery of this application embodiment, the second battery cell with a smaller full-charge expansion force can absorb the expansion amount of the first battery cell with a larger full-charge expansion force, reducing the overall expansion force of the multiple battery cells and preventing components adjacent to or connected to the multiple battery cells from being squeezed, broken, or torn, thereby improving the reliability and safety of the battery.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and more particularly to a battery and an electrical device. Background Technology

[0002] During battery cycling, individual cells expand, resulting in an expansion force. This expansion force gradually increases with the number of battery cycles. Different battery cells exhibit varying expansion forces, and this difference in expansion force increases with the number of battery cycles.

[0003] As batteries become more widely used, in some cases, in order to enable batteries to have greater power to drive large devices, multiple battery cells are often combined to form a battery. When a battery contains a large number of battery cells, the overall expansion force generated when multiple battery cells expand at the same time is also greater. The components adjacent to or connected to multiple battery cells are squeezed or torn, and the reliability and safety of the battery are reduced accordingly. Summary of the Invention

[0004] In view of the above problems, embodiments of this application provide a battery and an electrical device that can reduce the degree and force of outward expansion of the overall size of multiple battery cells, thereby improving the reliability and safety of the battery.

[0005] According to one aspect of the embodiments of this application, a battery is provided, the battery including a plurality of battery cells arranged sequentially in the same direction, the battery cells including a first battery cell and a second battery cell; the full charge expansion force of the first battery cell is greater than that of the second battery cell, and the first battery cell and the second battery cell are configured such that when the number of battery electrical cycles is greater than or equal to 500, the difference in full charge expansion force between the first battery cell and the second battery cell is greater than or equal to 400N.

[0006] By adopting the above scheme, as the number of battery cycles increases, the difference in full-charge expansion force between the first battery cell and the second battery cell increases. In this case, the first battery cell with a larger full-charge expansion force expands outward to a greater extent. Furthermore, the expansion force acts on the second battery cell with a smaller expansion force, causing it to undergo inward deformation. That is, the second battery cell with a smaller full-charge expansion force can absorb the expansion amount of the first battery cell with a larger full-charge expansion force, reducing the overall outward expansion force of multiple battery cells. This prevents components adjacent to or connected to multiple battery cells from being squeezed, broken, or torn, thereby improving the reliability and safety of the battery.

[0007] In some embodiments, the first battery cell and the second battery cell are configured such that the difference in full-charge expansion force between the first battery cell and the second battery cell is less than or equal to 4000N when the number of battery electrical cycles is greater than or equal to 500.

[0008] By adopting the above scheme, when the difference in full-charge expansion force between the first and second battery cells is too large, at least two situations exist. The first is that the full-charge expansion force of the first battery cell is too large, which may lead to risks such as casing cracking or electrode breakage, reducing battery safety. The second is that the full-charge expansion force of the second battery cell is too small, which may lead to severe deformation of the second battery cell, rendering it unusable. Alternatively, there may be a large gap between the electrode assembly and the casing, resulting in a lower energy density of the second battery cell, and consequently a lower overall energy density of the battery. Therefore, by controlling the difference in full-charge expansion force between the first and second battery cells to be less than or equal to 4000N, the battery can achieve both safety and reliability while also possessing a high energy density.

[0009] In some embodiments, the first battery cell includes a first negative electrode sheet, the second battery cell includes a second negative electrode sheet, the first negative electrode sheet includes a first negative electrode active material layer, the second negative electrode sheet includes a second negative electrode active material layer, and the full charge compaction density of the first negative electrode active material layer is greater than the full charge compaction density of the second negative electrode active material layer.

[0010] By adopting the above scheme, after the negative electrode active material is wetted by the electrolyte, the ion embedding in the negative electrode active material layer during charging causes a change in the lattice spacing, forming microscopic internal stress that causes the electrode sheet to expand. The first negative electrode active material has a larger full-charge compaction density, and after being wetted by the electrolyte, the volume expansion per unit volume of the first negative electrode active material layer due to the change in lattice spacing is larger, resulting in a larger dimensional expansion of the first negative electrode sheet. Conversely, the second negative electrode active material layer has a smaller full-charge compaction density, and after being wetted by the electrolyte, the volume expansion per unit volume of the second negative electrode active material layer due to the change in lattice spacing is smaller. This achieves the effect that the full-charge expansion force of the first battery cell is greater than that of the second battery cell.

[0011] In some embodiments, the first battery cell and the second battery cell are configured such that, when the number of battery electrical cycles is greater than or equal to 500, the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer is greater than or equal to 0.3 g / cm³. 3 .

[0012] By adopting the above scheme, by setting the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer, the difference between the full-charge expansion of the first battery cell and the second battery cell can be increased, thereby increasing the difference between the full-charge expansion force of the first battery cell and the second battery cell, so that the first battery cell and the second battery cell can be used together to reduce the change in the overall size of the group of multiple battery cells due to the expansion of the battery cells.

[0013] In some embodiments, the first battery cell and the second battery cell are configured such that, when the number of battery electrical cycles is greater than or equal to 500, the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer is less than or equal to 1 g / cm³. 3 .

[0014] By adopting the above scheme, the problems of ion intercalation difficulty and excessive expansion force of the first battery cell caused by excessive full-charge compaction density can be prevented, and the energy density of the second battery cell can be reduced due to excessively low full-charge compaction density.

[0015] In some embodiments, the first battery cell includes a first negative electrode, the second battery cell includes a second negative electrode, the first negative electrode is made of graphite, and the second negative electrode is made of hard carbon or an alloy material.

[0016] By adopting the above scheme, since the hardness, liquid absorption and compressibility of graphite are greater than those of hard carbon and alloy materials, the full-charge expansion force of the first negative electrode sheet under the same conditions is greater than that of the second negative electrode sheet. The second battery cell composed of the second negative electrode sheet absorbs part of the full-charge expansion generated by the first battery cell composed of the first negative electrode sheet, so that the full-charge expansion force of the multiple battery cells is greatly reduced.

[0017] In some embodiments, the first battery cell is a lithium-ion battery cell, and the second battery cell is a sodium-ion battery cell.

[0018] By adopting the above scheme, under the same structure and usage environment, lithium-ion battery cells are more likely to generate greater expansion force, while sodium-ion battery cells generate less expansion force than lithium-ion battery cells. Therefore, it is possible to control the expansion force of the first and second battery cells by controlling the difference in the positive electrode materials of the first and second battery cells.

[0019] In some embodiments, the battery includes M first battery cells and N second battery cells, wherein 0.1 ≤ N / (M+N) ≤ 0.6.

[0020] By adopting the above scheme, when the number of the second battery cell accounts for less than 0.1% of all battery cells, the large number of first battery cells results in a larger total outward expansion size, while the total inward space formed by the second battery cell during its interaction with the first battery cell is smaller. This leads to a greater overall outward expansion and thus a larger outward expansion force when the first and second battery cells are used together. When the number of the second battery cell accounts for more than 0.6% of all battery cells, the total inward space formed by the second battery cell during its interaction with the first battery cell is larger. During repeated electrical cycles causing deformation of the second battery cell, the contact between multiple battery cells is loose, and the battery cells cannot form a good positioning. When the battery vibrates during use, the battery cells are prone to shaking, leading to unstable electrical connections. The above-defined range increases the reliability and safety of the battery while also considering the stability of the battery structure and electrical connections, thus improving the overall quality and lifespan of the battery.

[0021] In some embodiments, the first battery cell and the second battery cell are arranged adjacent to each other.

[0022] By adopting the above scheme, each first battery cell can directly squeeze the adjacent second battery cell after it expands, causing the second battery cell to deform. The second battery cell absorbs the expansion amount of the first battery cell through concave deformation, thereby reducing the overall expansion force generated by multiple battery cells.

[0023] In some embodiments, the battery further includes two end plates perpendicular to the arrangement direction of the plurality of battery cells, each end plate being disposed at one end of the plurality of battery cells and disposed adjacent to the first battery cell.

[0024] By adopting the above scheme, the end plate is used to resist the expansion force of multiple battery cells during charging and discharging, and to confine the multiple battery cells within a certain range, making the battery structure more stable. During the assembly process, there is often an installation gap between the end plate and the battery cells. This gap can be used to accommodate a portion of the deformation of the battery cells. By setting the end plate and the first battery cell to be adjacent, the gap will decrease or disappear after the first battery cell expands, thereby reducing the outward deformation of the end plate and thus reducing the degree of outward deformation of the overall size after the battery cells are assembled.

[0025] In some embodiments, the battery further includes an elastic element disposed between two adjacent first battery cells.

[0026] By adopting the above scheme, when two first battery cells are adjacent, the expansion force generated between the two first battery cells is greater than the expansion force between the first battery cells and the second battery cells, and much smaller than the expansion force between two adjacent second battery cells. Therefore, setting the elastic element between two adjacent first battery cells can leave a gap between the two first battery cells so that the expansion amount generated by the two first battery cells can be released in the gap, thereby reducing the overall expansion force of multiple battery cells.

[0027] According to another aspect of the embodiments of this application, an electrical device is provided, including a battery of any of the above-described embodiments, the battery being used to provide electrical energy.

[0028] By adopting the above solution, the safety of electrical appliances is enhanced.

[0029] This application embodiment uses two battery cells with significantly different full-charge expansion forces as components of the battery. In the fully charged state, the second battery cell with a smaller full-charge expansion force absorbs the expansion of the first battery cell with a larger full-charge expansion force, thereby reducing the overall expansion force of multiple battery cells and preventing components adjacent to or connected to multiple battery cells from being squeezed, broken, or torn, thus improving the reliability and safety of the battery.

[0030] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of an electrical device in one embodiment of this application.

[0033] Figure 2 This is a partially exploded structural diagram of a battery according to one embodiment of this application.

[0034] Figure 3 This is a schematic diagram of the arrangement of multiple battery cells in one embodiment of this application.

[0035] Figure 4 This is a schematic diagram showing the positional relationship between the end plate and multiple battery cells in one embodiment of this application.

[0036] Figure 5 This is a schematic diagram showing the installation position and structure of the elastic element in one embodiment of this application.

[0037] Figure 6 This is a schematic diagram of an elastic element in another embodiment of this application.

[0038] Explanation of reference numerals in the attached drawings: 2, automobile; 200, battery; 210, controller; 220, motor; 301, upper housing; 302, lower housing; 400, battery cell; 401, first battery cell; 402, second battery cell; 500, end plate; 600, elastic element. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and drawings of this application are intended to cover without excluding other meanings. The words "a" or "an" do not exclude the presence of multiples.

[0042] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0043] In this article, the term "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 article generally indicates that the preceding and following related objects have an "or" relationship.

[0044] The directional terms appearing in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the battery or electrical device of this application. For example, in the description of this application, terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] Furthermore, the descriptions of directions such as the X, Y, and Z directions used to explain the operation and construction of the components of the battery or electrical device in this embodiment are not absolute but relative. Although these directions are appropriate when the components of the battery pack are in the positions shown in the figure, they should be interpreted differently when these positions change to correspond to the changes.

[0046] Furthermore, the terms "first," "second," etc., in the specification and claims of this application or in the aforementioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.

[0047] In the description of this application, unless otherwise stated, "multiple" means two or more (including two), and similarly, "multiple groups" means two or more (including two groups).

[0048] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, "connection" or "linkage" in mechanical structures can refer to a physical connection, such as a fixed connection, for example, a connection fixed by fasteners, such as a connection fixed by screws, bolts, or other fasteners; a physical connection can also be a detachable connection, such as a snap-fit ​​or interlocking connection; a physical connection can also be an integral connection, such as a connection formed by welding, bonding, or integral molding. In circuit structures, "connection" or "linkage" can refer not only to a physical connection but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate component, as long as the circuit is connected; it can also refer to the internal connection of two components. Signal connection can refer not only to signal connection through a circuit but also to signal connection through a media, such as radio waves. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0049] The battery includes a housing and individual battery cells. The housing has a receiving cavity in which multiple individual battery cells are placed.

[0050] A battery cell includes a casing, electrode assembly, and electrolyte. The electrode assembly consists of a positive electrode, a negative electrode, and a separator. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode plates. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated current collector protrudes beyond the coated current collector, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the positive current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated current collector protrudes beyond the coated current collector, serving as the negative electrode tab. The negative current collector can be made of copper, and the negative active material can be carbon or silicon, etc. To ensure that a large current can be carried without melting, multiple positive electrode tabs are stacked together, and multiple negative electrode tabs are stacked together. The insulating material can be PP or PE, etc. Furthermore, the electrode assembly can be a wound structure or a stacked structure; the embodiments of this application are not limited to these.

[0051] During battery cycling, the electrode assembly expands, pressing outward against the casing and causing it to bulge. When multiple battery cells bulge outward simultaneously, it can lead to insufficient space within the casing. Excessive pressure on the casing walls or other components within the battery may cause them to break. Furthermore, the components used to connect the multiple battery cells may be torn, resulting in unstable battery output and reduced battery reliability and safety.

[0052] In view of the above problems, this application provides a battery that uses two battery cells with significantly different full-charge expansion forces as components of the battery. In the fully charged state, the second battery cell with a smaller full-charge expansion force absorbs the expansion of the first battery cell with a larger full-charge expansion force, thereby reducing the overall expansion force of multiple battery cells. This reduces the expansion force that the end plate needs to withstand, prevents the end plate from breaking due to excessive force, and improves the reliability and safety of the battery.

[0053] The battery provided in this application embodiment can be applied to various battery-using devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, electric vehicles, ships, and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft, but are not limited thereto.

[0054] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of an electrical device according to an embodiment of this application. Taking a car 2 as an example, the car 2 can be a gasoline car, a natural gas car, or a new energy vehicle. A new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. The car 2 includes a battery 200, a controller 210, and a motor 220. The battery 200 supplies power to the controller 210 and the motor 220, serving as the operating power and drive power for the car 2. For example, the battery 200 meets the power requirements for starting, navigation, and operation of the car 2. For instance, the battery 200 supplies power to the controller 210, which controls the battery 200 to supply power to the motor 220. The motor 220 receives and uses the power from the battery 200 as the drive power for the car 2, replacing or partially replacing gasoline or natural gas to provide driving power for the car 2.

[0055] like Figure 2As shown, to enable the battery 200 to achieve higher functionality to meet usage requirements, the battery 200 may include an upper housing 301 and a lower housing 302 that are interlocked. A space is formed between the upper housing 301 and the lower housing 302 to accommodate multiple battery cells 400. The multiple battery cells 400 are located within this space and are electrically connected to each other. The multiple battery cells 400 can be electrically connected in series, parallel, or a combination thereof to achieve higher current or voltage. A combination thereof refers to a combination of series and parallel connections. Furthermore, the multiple battery cells 400 can be arranged according to a predetermined rule, such as... Figure 2 As shown, the battery cell 400 can be placed upright. The height of the battery cell 400 is aligned with the Z direction, the length of multiple battery cells 400 is aligned with the X direction, and the width of multiple battery cells 400 is aligned with the Y direction.

[0056] In this embodiment, the height, length, and width directions of the battery cell 400 are mutually perpendicular. The height direction of the battery cell 400 can refer to the direction in which the electrode terminals are led out. The width dimension of the battery cell 400 is less than or equal to the length dimension. During use, the battery cell 400 expands along both the length and width directions, and generally the expansion along the width direction is greater than the expansion along the length direction. Therefore, the full-charge expansion force of the battery cell 400 in the width direction is greater than the full-charge expansion force of the battery cell 400 in the length direction.

[0057] like Figure 2 and Figure 3 As shown, in some embodiments, the battery 200 includes a plurality of battery cells 400 arranged sequentially in the same direction. Each battery cell 400 includes a first battery cell 401 and a second battery cell 402. The full-charge expansion force of the first battery cell 401 is greater than that of the second battery cell 402. The first battery cell 401 and the second battery cell 402 are configured such that when the number of electrical cycles of the battery 200 is greater than or equal to 500, the difference in full-charge expansion force between the first battery cell 401 and the second battery cell 402 is greater than or equal to 400N.

[0058] In the above embodiments, the arrangement direction of the plurality of battery cells 400 can be the same as the length direction of the battery cell 400, that is... Figure 2 In the X direction, or the arrangement direction of multiple battery cells 400, can be the same as the width direction of the battery cell 400, that is... Figure 2The Y direction in the middle. Considering that the full charge expansion force of a typical battery cell 400 in the width direction is greater than that in the length direction, the arrangement direction of the multiple battery cells 400 in this embodiment is the same as the width direction of the battery cell 400. Of course, in other embodiments of this application, the arrangement direction of the multiple battery cells 400 can also be set to the length direction of the battery cell 400.

[0059] One electrical cycle of battery 200 refers to one process of charging battery 200 to a fully charged state and then discharging it to a fully discharged state. A fully charged state refers to a state where the battery 200's state of charge is greater than 97%, and a fully discharged state refers to a state where the battery 200's state of charge is less than 3%.

[0060] The difference in full-charge expansion force of battery 200 can be obtained by measuring the full-charge expansion force of the first battery cell 401 and the second battery cell 402, and then subtracting the full-charge expansion force of the first battery cell 401 and the second battery cell 402. Here, full-charge expansion force refers to the expansion force of battery cell 400 in a fully charged state.

[0061] In this application embodiment, the number of first battery cells 401 and the number of second battery cells 402 are not limited. As long as any one battery cell 400 and the other battery cell 400 meet the above-mentioned limitations in this application embodiment, the two battery cells 400 can be considered to meet the conditions of the first battery cell 401 and the second battery cell 402.

[0062] Different battery cells 400 have varying full-charge expansion forces, and the difference in full-charge expansion forces between different battery cells 400 gradually increases as the number of electrical cycles of the battery 200 increases. Therefore, in this embodiment, the difference in full-charge expansion forces between the first battery cell 401 and the second battery cell 402 is measured when the number of electrical cycles of the battery 200 is greater than or equal to 500, so that this difference can be amplified to increase the accuracy of the full-charge expansion force difference.

[0063] In the use of the battery 200 of this application embodiment, because the first battery cell 401 has a large expansion force when fully charged, the first battery cell 401 expands and protrudes a large amount when fully charged, while the second battery cell 402 expands and protrudes a small amount or does not expand and protrude at all when fully charged. Alternatively, when the first battery cell 401 protrudes and squeezes the second battery cell 402, the shell of the second battery cell 402 can be concave to accommodate part of the dimensional expansion of the first battery cell 401, thereby reducing the overall outward expansion force of the multiple battery cells 400 in the arrangement direction, preventing the components adjacent to or connected to the multiple battery cells 400 from breaking due to excessive force, and improving the reliability and safety of the battery 200.

[0064] In some embodiments, the first battery cell 401 and the second battery cell 402 are configured such that when the number of electrical cycles of the battery 200 is greater than or equal to 500, the difference in the full-charge expansion force between the first battery cell 401 and the second battery cell 402 is less than or equal to 4000N.

[0065] If the difference in full-charge expansion force between the first battery cell 401 and the second battery cell 402 is too large, at least two situations arise. First, the excessive full-charge expansion force of the first battery cell 401 may lead to risks such as casing rupture or electrode breakage, reducing the safety of the battery 200. Second, the insufficient full-charge expansion force of the second battery cell 402 results in a lower energy density for the second battery cell 402, consequently lower overall energy density of the battery 200. Therefore, this embodiment of the application controls the difference in full-charge expansion force between the first battery cell 401 and the second battery cell 402 to be less than or equal to 4000N, thereby enabling the battery 200 to possess both safety and reliability while also achieving a higher energy density.

[0066] In some embodiments, the first battery cell 401 includes a first negative electrode sheet, the second battery cell 402 includes a second negative electrode sheet, the first negative electrode sheet includes a first negative electrode active material layer, the second negative electrode sheet includes a second negative electrode active material layer, and the full charge compaction density of the first negative electrode active material layer is greater than the full charge compaction density of the second negative electrode active material layer.

[0067] The first negative electrode sheet includes a first negative electrode current collector and a first negative electrode active material layer. The first negative electrode current collector may be copper, and the first negative electrode active material layer may include one or more of carbon-based negative electrode materials, tin-based negative electrode materials, alloy-based negative electrode materials, and silicon-based negative electrode materials.

[0068] Similarly, the second negative electrode sheet has the same or similar structure as the first negative electrode sheet. The materials of the second negative electrode active material layer and the first negative electrode active material layer can be the same or different, as long as the full-charge compaction density of the first negative electrode active material layer is greater than that of the second negative electrode active material layer.

[0069] The full-charge compaction density of the first negative electrode active material layer refers to the ratio of the weight of the first negative electrode active material layer per unit area to the volume of the first negative electrode sheet per unit area when the battery is fully charged to 200%. Similarly, the definition of the full-charge compaction density of the second negative electrode active material layer is basically the same as that of the first negative electrode active material layer, and will not be repeated in the embodiments of this application.

[0070] After being wetted by the electrolyte, the negative electrode active material undergoes ion embedding during charging, causing a change in the lattice spacing and creating microscopic internal stress that leads to electrode expansion. Because the first negative electrode active material layer has a higher full-charge compaction density, the volume expansion per unit volume due to the lattice spacing change after electrolyte wetting is greater, resulting in a larger dimensional expansion of the first negative electrode sheet. Conversely, the second negative electrode active material layer has a lower full-charge compaction density, resulting in a smaller volume expansion per unit volume due to the lattice spacing change after electrolyte wetting, resulting in a smaller dimensional expansion of the second negative electrode sheet. Therefore, it is possible to achieve a full-charge expansion force greater for the first battery cell 401 than for the second battery cell 402.

[0071] In some embodiments, the first battery cell 401 and the second battery cell 402 are configured such that, when the number of electrical cycles of the battery 200 is greater than or equal to 500, the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer is greater than or equal to 0.3 g / cm³. 3 .

[0072] By adopting the above scheme, by limiting the lower limit of the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer, the lower limit of the difference between the full-charge expansion force of the first battery cell 401 and the second battery cell 402 is limited, so that the first battery cell 401 and the second battery cell 402 can be used together to reduce the change in the overall size of the group of multiple battery cells 400 due to the expansion of the battery cells 400.

[0073] In some embodiments, the first battery cell 401 and the second battery cell 402 are configured such that, when the number of electrical cycles of the battery 200 is greater than or equal to 500, the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer is less than or equal to 1 g / cm³.3 .

[0074] When the difference between the full-charge compaction density of the first negative electrode active material layer and the full-charge compaction density of the second negative electrode active material layer is too large, it may indicate that the full-charge compaction density of the first battery cell 401 is too high. This situation can easily lead to difficulties in ion intercalation, or it may cause severe outward deformation of the first battery cell 401 or even shell cracking, shortening the service life of the first battery cell 401. Alternatively, it may indicate that the full-charge compaction density of the second battery cell 402 is too low. This situation can easily lead to a lower energy density of the second battery cell 402, affecting the overall capacity of the battery 200.

[0075] Therefore, in this embodiment, the difference between the full-fill compaction density of the first negative electrode active material layer and the full-fill compaction density of the second negative electrode active material layer is controlled to be less than or equal to 1 g / cm³. 3 This prevents the difference between the full-fill compaction density of the first negative electrode active material layer and the full-fill compaction density of the second negative electrode active material layer from becoming too large, thereby preventing and to some extent avoiding the occurrence of the two possible situations mentioned above.

[0076] In some embodiments, the first battery cell 401 includes a first negative electrode, the second battery cell 402 includes a second negative electrode, the material of the first negative electrode includes graphite, and the material of the second negative electrode includes hard carbon or an alloy material.

[0077] By adopting the above scheme, since the hardness, liquid absorption and compressibility of graphite are greater than those of hard carbon and alloy materials, the full-charge expansion force of the first battery cell 401 containing the first negative electrode sheet is greater than that of the second battery cell 402 containing the second negative electrode sheet under the same conditions. The first battery cell 400 absorbs part of the full-charge expansion of the first battery cell 401, so that the expansion force exhibited by the multiple battery cells 400 is greatly reduced.

[0078] In some embodiments, the first battery cell 401 is a lithium-ion battery cell, and the second battery cell 402 is a sodium-ion battery cell.

[0079] By adopting the above scheme, under the same structure and usage environment, lithium-ion battery cells are more likely to generate larger expansion forces, while sodium-ion battery cells generate smaller expansion forces than lithium-ion battery cells. Therefore, it is possible to control the expansion forces of the first battery cell 401 and the second battery cell 402 by controlling the difference in the positive electrode materials of the first battery cell 401 and the second battery cell 402.

[0080] The above embodiments define various possible configurations for the first battery cell 401 and the second battery cell 402. However, for the entire battery 200, the overall expansion force exhibited by the multiple battery cells 400 depends on the number of first battery cells 401 and the number of second battery cells 402. When the proportion of the second battery cells 402 among all battery cells 400 is small, the expansion of a larger number of first battery cells 401 results in a larger total outward expansion of the entire group of battery cells 400, while the total inward concave space formed by the second battery cells 402 during their interaction with the first battery cells 401 is smaller. When the first battery cells 401 and the second battery cells 402 are used together, this situation tends to lead to a larger degree of outward expansion of the entire group of battery cells 400, resulting in a larger overall outward expansion force after the battery cells 400 are grouped together.

[0081] When the number of second battery cells 402 accounts for a large proportion of all battery cells 400, on the one hand, the total amount of concave space that the second battery cells 402 can form during their interaction with the first battery cells 401 is large, but the total amount of outward expansion space of the first battery cells 401 is small. This can easily lead to low space utilization and low energy density of the second battery cells 402, affecting the overall energy density of the battery 200. On the other hand, during repeated electrical cycles that cause deformation of the second battery cells 402, the second battery cells 402 are prone to deformation, which can easily lead to loose contact between multiple battery cells 400. The battery cells 400 cannot form good positioning, and when the battery 200 vibrates during use, the battery cells 400 are prone to shaking, making the electrical connection of the battery 200 unstable.

[0082] To verify the impact of the number of first battery cells 401 and second battery cells 402 on the performance of battery 200, and to determine the optimal ratio of the number of first battery cells 401 and second battery cells 402 contained in battery 200, this application conducted the following experiments. Eight different types of batteries 200 were selected in the experiments. The difference between each type of battery 200 lies in the number of first battery cells 401 and second battery cells 402 contained. Expansion force test, vibration test and cycle life test were performed on each type of battery 200, and the experimental values ​​obtained are recorded in the table below.

[0083]

[0084]

[0085] The data recorded in the table shows that as the proportion of the second battery cell 402 increases, the expansion force of the battery 200 decreases, the cycle life of the battery 200 increases when its capacity drops to 80%, and the vibration test pass rate of the battery 200 decreases after the proportion of the second battery 200 exceeds 60%.

[0086] Therefore, in order to enable the battery 200 to have lower expansion force, longer cycle life and better stability under vibration, in some embodiments, the battery 200 includes M first battery cells 401 and N second battery cells 402, wherein 0.1≤N / (M+N)≤0.6.

[0087] When the number of the first battery cell 401 and the number of the second battery cell 402 are within the range defined in this embodiment, the reliability and safety of the battery 200 are increased while the stability of the battery 200 structure and the stability of the battery 200 electrical connection are taken into account, thereby improving the overall performance and lifespan of the battery 200.

[0088] like Figure 3 As shown, in some embodiments, the first battery cell 401 and the second battery cell 402 are arranged adjacent to each other.

[0089] The first battery cell 401 may be adjacent to the second battery cell 402 on one side or on both sides. Similarly, the second battery cell 402 may be adjacent to the first battery cell 401 on one side or on both sides.

[0090] By adopting the above scheme, each first battery cell 401 can directly squeeze the adjacent second battery cell 402 after it expands, causing the second battery cell 402 to deform. The second battery cell 402 absorbs the expansion amount of the first battery cell 401 through concave deformation, thereby reducing the expansion force generated by the multiple battery cells 400 as a whole.

[0091] like Figure 4 As shown, in some embodiments, the battery 200 further includes two end plates 500 arranged perpendicular to the battery arrangement direction. Each end plate 500 is disposed at one end of a plurality of battery cells 400 and is disposed adjacent to the first battery cell 401.

[0092] The end plate 500 can be made of a metallic material, such as aluminum or aluminum alloy. A metallic end plate 500 can withstand the expansion forces of multiple battery cells 400 during charging and discharging. The end plate 500 can also be made of a non-metallic material, such as polycarbonate-ABS resin composite (PC-ABS), polypropylene (PP), or fusible polytetrafluoroethylene (FPA). A non-metallic end plate 500 can prevent short circuits between the end plate 500 itself and the battery cells 400. The end plate 500 can also be a composite of metallic and non-metallic materials; for example, a non-metallic material can be laminated onto a metallic outer layer.

[0093] The two end plates 500 are used to resist the expansion force of multiple battery cells 400 during the charging and discharging process and to confine the multiple battery cells 400 within a certain range, making the battery 200 structure more stable.

[0094] The end plate 500 is a component used to resist the dimensional expansion of multiple battery cells 400 along their width direction during charge and discharge cycles. The end plate 500 and the side plate are used together to limit the multiple battery cells 400, thereby making the overall structure of the battery 200 more stable. During the assembly of the battery 200, there may be an installation gap between the end plate 500 and the multiple battery cells 400. This gap can be used to accommodate a portion of the expansion deformation of the battery cells 400. By setting the end plate 500 adjacent to the first battery cell 401, the gap will decrease or disappear after the first battery cell 401 expands, thereby reducing the outward deformation of the end plate 500 and thus reducing the degree of outward deformation and expansion of the overall size of the multiple battery cells 400 after assembly.

[0095] Since each first battery cell 401 expands after being fully charged, the battery cells 400 at both ends of the battery cell arrangement direction can bulge to both sides after expansion, while the expansion space of the battery cell 400 located in the middle of the battery cell arrangement direction is limited by the battery cells 400 located at both ends, making its expansion space limited. Therefore, in order to prevent the battery cell 400 located in the middle of the arrangement of multiple battery cells 400 from being over-compressed, in some embodiments, the second battery cell 402 is located in the middle position of the arrangement of multiple battery cells 400.

[0096] The middle position of the arrangement of multiple battery cells 400 can be any position located in the middle 1 / 3 of the battery cells 400. For example, if 30 battery cells 400 are arranged in the order of 1, 2, 3...28, 29, 30, then the middle position of the arrangement of multiple battery cells 400 can be any position in the interval where the 21st to 30th battery cells 400 are located.

[0097] It should be noted that the second battery cell 402 being located in the middle of the arrangement of multiple battery cells 400 does not mean that the second battery cell 402 is the only one in the middle of the arrangement of multiple battery cells 400, nor does it mean that the second battery cell 402 is not present in other positions in the arrangement of multiple battery cells 400. Rather, the second battery cell 402 is present in the middle of the arrangement of multiple battery cells 400.

[0098] like Figure 5 As shown, in some embodiments, the battery 200 further includes an elastic element 600 disposed between two adjacent first battery cells 401.

[0099] The elastic element 600 can possess high-temperature resistance and corrosion resistance properties, thus adapting to the environment of the battery 200. The elastic element 600 has a certain degree of elasticity, and its material can be non-metallic materials such as plastics, rubber, polymer resins, etc., with a hardness lower than that of the battery cell 400's casing, to prevent damage to the battery cell 400's casing under expansion force. The elastic element 600 can be configured as a strip, sheet, column, or other shapes.

[0100] When two first battery cells 401 are adjacent, the expansion force generated between the two first battery cells 401 is greater than the expansion force between the first battery cell 401 and the second battery cell 402, and much smaller than the expansion force between two adjacent second battery cells 402. Therefore, setting the elastic member 600 between two adjacent first battery cells 401 can leave a gap between the two first battery cells 401 so that the expansion generated by the two first battery cells 401 can be released in the gap, thereby reducing the overall expansion force of the multiple battery cells 400.

[0101] like Figure 5 As shown, in some embodiments, the elastic element 600 is strip-shaped and is disposed near the two opposite sides of the first battery cell 401.

[0102] The location where the battery cell 400 expands the most is in the middle region of the adjacent surfaces of the battery cell 400. Therefore, the elastic member 600 provided in this embodiment will not occupy the expansion space in the middle of the adjacent surfaces of the adjacent battery cells 400, so that the two adjacent first battery cells 401 have enough space to release their expansion force.

[0103] like Figure 6 As shown, in some embodiments, the elastic element 600 is L-shaped and is respectively disposed at the corners of the first battery cell 401.

[0104] The expansion amount of the first battery cell 401 is small at the corner. Placing the elastic element 600 at this location helps to reserve more expansion space for two adjacent first battery cells 401.

[0105] According to another aspect of the embodiments of this application, an electrical device is provided, including a battery 200 of any of the above-described embodiments, the battery 200 being used to provide electrical energy.

[0106] By adopting the above solution, the electrical device is safer and has a lower failure rate due to the high reliability and safety of battery 200.

[0107] This embodiment of the application uses two battery cells 400 with significantly different full-charge expansion forces as components of the battery 200. In the fully charged state, the second battery cell 402 with a smaller full-charge expansion force absorbs the expansion of the first battery cell 401 with a larger full-charge expansion force, thereby reducing the overall expansion force of the multiple battery cells 400. This reduces the expansion force that the end plate 500 needs to withstand, preventing the end plate 500 from breaking due to excessive force, and improving the reliability and safety of the battery 200.

[0108] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0109] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A battery, characterized by include: Multiple battery cells arranged sequentially along the same direction, wherein the battery cells include a first battery cell and a second battery cell; The full-charge expansion force of the first battery cell is greater than that of the second battery cell, and the first battery cell and the second battery cell are configured such that the difference in full-charge expansion force between the first battery cell and the second battery cell is greater than or equal to 400N when the number of electrical cycles of the battery is greater than or equal to 500. The first battery cell and the second battery cell are configured such that when the number of electrical cycles of the battery is greater than or equal to 500, the difference in the full-charge expansion force between the first battery cell and the second battery cell is less than or equal to 4000N.

2. The battery according to claim 1, characterized in that, The first battery cell includes a first negative electrode sheet, and the second battery cell includes a second negative electrode sheet. The first negative electrode sheet includes a first negative electrode active material layer, and the second negative electrode sheet includes a second negative electrode active material layer. The full charge compaction density of the first negative electrode active material layer is greater than that of the second negative electrode active material layer.

3. The battery according to claim 2, characterized in that, The first battery cell and the second battery cell are configured such that a difference between a full charge density of the first negative electrode active material layer and a full charge density of the second negative electrode active material layer is greater than or equal to 0.3 g / cm3 when a number of electrical cycles of the battery is greater than or equal to 500. 3 .

4. The battery according to claim 3, characterized in that, The first battery cell and the second battery cell are configured such that a difference between a full charge density of the first negative electrode active material layer and a full charge density of the second negative electrode active material layer is less than or equal to 1 g / cm3 when a number of electrical cycles of the battery is greater than or equal to 500. 3 .

5. The battery according to claim 1, characterized in that, The first battery cell includes a first negative electrode, and the second battery cell includes a second negative electrode. The material of the first negative electrode includes graphite, and the material of the second negative electrode includes hard carbon or an alloy material.

6. The battery according to claim 1, characterized in that, The first battery cell is a lithium-ion battery cell, and the second battery cell is a sodium-ion battery cell.

7. The battery according to any one of claims 1-6, characterized in that, The battery comprises M first battery cells and N second battery cells, wherein 0.1 ≤ N / (M+N) ≤ 0.

6.

8. The battery according to any one of claims 1-6, characterized in that, The first battery cell and the second battery cell are arranged adjacent to each other.

9. The battery according to any one of claims 1-6, characterized in that, The battery also includes two end plates perpendicular to the arrangement direction of the plurality of battery cells. Each end plate is disposed at one end of the plurality of battery cells and is disposed adjacent to the first battery cell.

10. The battery according to any one of claims 1-6, characterized in that, The battery also includes an elastic element disposed between two adjacent first battery cells.

11. An electrical appliance, characterized in that, The battery includes any one of claims 1 to 10, the battery being used to provide electrical energy.

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