Battery monomer, battery pack and power utilization device

Abstract

The utility model provides a battery monomer, a battery pack and a power utilization device, the battery monomer comprises a battery cell assembly and a heat exchange piece, the battery cell assembly comprises at least one lithium iron phosphate battery cell and at least one ternary lithium battery cell, and the lithium iron phosphate battery cells and the ternary lithium battery cells are sequentially and alternately connected in series; and the heat exchange piece is arranged on at least one large surface side of the battery cell assembly along the first direction and covers the large surface sides of all the lithium iron phosphate battery cells and the ternary lithium battery cells. Furthermore, the battery monomer is designed into a battery monomer structure in which the lithium iron phosphate battery cells and the ternary lithium battery cells are sequentially and alternately connected in series and matched, and the charging performance and the energy density of the whole battery monomer are improved by utilizing the advantage that the ternary lithium battery cells are better in charging performance at a low temperature; the temperature difference between the lithium iron phosphate battery cell and the ternary lithium battery cell is balanced by using the heat exchange piece, so that the thermal stability and safety of the whole battery monomer are improved, and the whole battery monomer has better thermal stability, higher energy density and higher charging power.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery cell, a battery pack, and an electrical device. Background Technology

[0002] With the increasing application of batteries in new energy vehicles and small-scale grid energy storage, the requirements for battery energy density, cycle performance, and rate performance are also rising. Currently, the two most commonly used battery types are lithium iron phosphate (LFP) batteries and ternary lithium batteries. LFP batteries use lithium iron phosphate as the cathode material, while ternary lithium batteries use lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide as the cathode material. However, compared to LFP batteries, ternary lithium batteries have higher energy density, stronger charge / discharge performance, and more accurate SOC (State of Charge) display, but they also have disadvantages such as higher cost and poorer thermal stability. While LFP batteries have lower energy density, poorer low-temperature performance, and a longer plateau voltage compared to ternary lithium batteries, making it difficult for battery management systems to use voltage as a control standard and requiring frequent full charges to calibrate the SOC display, LFP batteries have lower cost, higher thermal stability, and longer lifespan. Utility Model Content

[0003] The purpose of this application is to provide a battery cell, a battery pack, and an electrical device to solve the technical problem that existing batteries cannot simultaneously achieve better thermal stability, higher energy density, and charging power.

[0004] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0005] In a first aspect, this application provides a battery cell, comprising: a cell assembly and a heat exchanger, wherein the cell assembly includes at least one lithium iron phosphate cell and at least one ternary lithium cell, and the lithium iron phosphate cell and the ternary lithium cell are connected in series alternately; the heat exchanger is disposed along a first direction on at least one large surface side of the cell assembly and covers the large surface side of all lithium iron phosphate cells and ternary lithium cells.

[0006] In one or more embodiments of this application, at least one lithium iron phosphate cell and at least one ternary lithium cell are arranged alternately in series along a second direction and / or a third direction, with the large facet of all lithium iron phosphate cells and ternary lithium cells facing the heat exchanger; the first direction, the second direction and the third direction are perpendicular to each other.

[0007] In one or more embodiments of this application, the battery cell assembly includes two lithium iron phosphate cells and one ternary lithium battery cell. The two lithium iron phosphate cells are arranged side by side along a second direction, and the ternary lithium battery cell is arranged below the two lithium iron phosphate cells along a third direction and is connected in series with the two lithium iron phosphate cells alternately.

[0008] In one or more embodiments of this application, the lithium iron phosphate battery cell includes a first positive tab and a first negative tab, and the ternary lithium battery cell includes a second positive tab and a second negative tab. The first negative tab of the lithium iron phosphate battery cell and the second positive tab of the ternary lithium battery cell are connected in series via a busbar, or the first positive tab of the lithium iron phosphate battery cell and the second negative tab of the ternary lithium battery cell are connected in series via a busbar.

[0009] In one or more embodiments of this application, the heat exchanger is a plate heat pipe, and the heat exchanger is provided with a flow channel that allows the phase change medium to flow, so that the phase change medium can exchange heat with the large surface side of the lithium iron phosphate battery cell and the ternary lithium battery cell respectively.

[0010] In one or more embodiments of this application, it further includes:

[0011] The positive terminal is connected to the first positive terminal of one of the lithium iron phosphate cells, or to the second positive terminal of one of the ternary lithium cells;

[0012] The negative terminal is connected to the first negative terminal of one of the lithium iron phosphate cells, or to the second negative terminal of one of the ternary lithium cells.

[0013] In one or more embodiments of this application, it further includes:

[0014] An insulating film is used to cover the outside of the battery cell assembly.

[0015] In one or more embodiments of this application, it also includes

[0016] The housing has a receiving cavity, the battery cell assembly is disposed in the receiving cavity, and the heat exchanger is disposed between the insulating film and the cavity wall.

[0017] Secondly, this application provides a battery pack, comprising:

[0018] Box, and

[0019] The battery cells described in any one of the first aspects are arranged sequentially in the housing along a first direction.

[0020] Thirdly, this application provides an electrical device including the battery pack described in the second aspect.

[0021] Based on the above technical solutions, the battery cell, battery pack, and power device provided in this application have at least the following beneficial technical effects:

[0022] The battery cell provided in this application includes a cell assembly and a heat exchanger. The cell assembly includes at least one lithium iron phosphate cell and at least one ternary lithium cell, which are connected in series alternately. The heat exchanger is disposed along a first direction on at least one large surface side of the cell assembly and covers the large surface side of all lithium iron phosphate and ternary lithium cells. This allows the battery cell to be designed with a structure of alternating series connection of lithium iron phosphate and ternary lithium cells. Utilizing the advantage of better charging performance of ternary lithium cells at low temperatures, the overall charging performance and energy density of the battery cell are improved. By covering the large surface side of all lithium iron phosphate and ternary lithium cells with the heat exchanger, the temperature difference between the lithium iron phosphate and ternary lithium cells can be balanced, improving the thermal stability and safety of the entire battery cell. This also reduces production costs, resulting in a battery cell with better thermal stability, higher energy density, and higher charging power. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a three-dimensional structural diagram of a battery cell provided in one or more embodiments of this application.

[0025] Figure 2 This is a schematic diagram of the structure of a battery cell assembly provided in one or more embodiments of this application.

[0026] Figure 3 This is a schematic diagram of the structure of a battery cell assembly provided in one or more embodiments of this application.

[0027] Figure 4 This is a schematic diagram of the structure of a battery cell assembly provided in one or more embodiments of this application.

[0028] Figure 5 This is a schematic diagram of the structure of a battery cell provided in one or more embodiments of this application.

[0029] Figure 6 yes Figure 5 The AA cross-section diagram is shown.

[0030] Figure 7 This is an exploded structural diagram of a battery cell provided in one or more embodiments of this application.

[0031] Figure 8This is a three-dimensional structural diagram of a battery cell assembly provided in one or more embodiments of this application.

[0032] Figure 9 This is a three-dimensional structural schematic diagram of a heat exchanger provided in one or more embodiments of this application.

[0033] Figure 10 This is a schematic diagram of the flow channel in a heat exchanger provided in one or more embodiments of this application.

[0034] Figure 11 This is a three-dimensional structural diagram of a battery pack provided in one or more embodiments of this application.

[0035] Figure 12 This is a graph showing the relationship between open-circuit voltage (OCV) and state of charge (SOC) in lithium iron phosphate cells and ternary lithium cells.

[0036] Figure 13 This is a graph showing the relationship between the open-circuit voltage (OCV) and the state of charge (SOC) of a single battery cell according to one or more embodiments of this application.

[0037] In the diagram: 1-cell battery; 2-casing; 100-positive terminal; 200-negative terminal; 201-flow channel; 101-lithium iron phosphate cell; 102-ternary lithium cell; 103-busbar; 1011-first positive tab; 1012-first negative tab; 1021-second positive tab; 1022-second negative tab; 10-cell assembly; 20-heat exchanger; 30-insulating film; 40-casing; 401-receiving cavity. Detailed Implementation

[0038] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0039] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0040] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0042] In related technologies, the batteries used in new energy vehicles are chemical batteries. Common chemical batteries include five types of power batteries: lead-acid, lithium titanate, lithium cobalt oxide, lithium iron phosphate, nickel-cobalt-lithium, and nickel-cobalt-aluminum. Among them, lithium iron phosphate (LFP) batteries and ternary lithium batteries (NCM) are currently the most commonly used batteries in the battery market due to their higher energy density and more stable performance. However, both ternary lithium batteries and lithium iron phosphate batteries have their own advantages and disadvantages. For example, ternary lithium batteries have the following advantages: 1. Higher low-temperature energy efficiency than lithium iron phosphate batteries. Lithium iron phosphate batteries have particularly low charging power below zero degrees Celsius, requiring the system to heat up to slowly restore charging capacity, while ternary lithium batteries can also have a large charging power at low temperatures. 2. Battery management systems (BMS) can more accurately display the remaining power. Because lithium iron phosphate has a long plateau voltage (the voltage plateau is very flat from 30% to 95% SOC), it is difficult for the BMS to use voltage as a control standard, requiring frequent full charges to calibrate the SOC display. Ternary lithium batteries have a steep voltage curve, making it easier to use voltage as the standard for State of Charge (SOC) display; 3. Ternary lithium batteries have higher energy density, allowing more energy to be stored in the same volume, resulting in longer driving range. However, ternary lithium batteries are weaker in terms of safety performance. Lithium iron phosphate batteries, on the other hand, have a cost advantage due to the use of fewer rare metals. However, poor low-temperature stability and inaccurate SOC estimation, along with issues such as low-temperature driving range, energy estimation, and battery weight, are common problems with lithium iron phosphate batteries, severely hindering their commercialization in the new energy vehicle sector.

[0043] Based on the above considerations, in order to solve the technical problem that existing batteries cannot simultaneously achieve better thermal stability, higher energy density, and charging power, this application provides a battery cell, including a cell assembly and a heat exchanger. The cell assembly includes at least one lithium iron phosphate cell and at least one ternary lithium cell, and the lithium iron phosphate cell and the ternary lithium cell are connected in series alternately. The heat exchanger is disposed along a first direction on at least one large surface side of the cell assembly and covers the large surface side of all lithium iron phosphate cells and ternary lithium cells.

[0044] In the technical solution of this application embodiment, the battery cell is designed as a battery cell structure in which lithium iron phosphate cells and ternary lithium cells are alternately connected in series. Taking advantage of the better charging performance of ternary lithium cells at low temperatures, the charging performance and energy density of the overall battery cell are improved. By covering the large side of all lithium iron phosphate cells and ternary lithium cells with heat exchange components, the temperature difference between lithium iron phosphate cells and ternary lithium cells can be balanced, thereby improving the thermal stability and safety of the entire battery cell. At the same time, the production cost is reduced, so that the entire battery cell has better thermal stability, higher energy density and charging power.

[0045] The battery cell provided in this application can be applied to various battery-powered devices, including but not limited to mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0046] The technical solutions of the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0047] Please refer to Figure 1 and Figure 7 This application provides a battery cell, including: a cell assembly 10 and a heat exchanger 20. The cell assembly 10 includes at least one lithium iron phosphate cell 101 and at least one ternary lithium cell 102, and the lithium iron phosphate cell 101 and the ternary lithium cell 102 are connected in series alternately. The heat exchanger 20 is disposed along a first direction X on at least one large surface side of the cell assembly 10 and covers the large surface side of all lithium iron phosphate cells 101 and ternary lithium cells 102.

[0048] It is understandable that the alternating series connection of lithium iron phosphate cells 101 and ternary lithium cells 102 can be an electrical connection where the arrangement of the lithium iron phosphate cells 101 and ternary lithium cells 102 is not limited, so as to form a current path inside the battery cell. The first direction X can be the thickness direction of the battery cell. The heat exchanger 20 can be disposed on one large surface side of the cell assembly 10, or on both large surface sides of the cell assembly 10. The fact that the heat exchanger 20 covers all large surface sides of the lithium iron phosphate cells 101 and ternary lithium cells 102 can be understood as the heat exchange surface of the heat exchanger 20 being able to cover all large surface sides of the lithium iron phosphate cells 101 and ternary lithium cells 102, so as to equalize the temperature difference of all lithium iron phosphate cells 101 and ternary lithium cells 102.

[0049] In the technical solution of this application embodiment, the battery cell 1 is designed as a battery cell structure in which lithium iron phosphate cells 101 and ternary lithium cells 102 are connected in series alternately. Taking advantage of the better charging performance of ternary lithium cells 102 at low temperatures, the overall charging performance and energy density of the battery cell are improved. A heat exchanger covers the large-area side of all lithium iron phosphate cells 101 and ternary lithium cells 102 to balance the temperature difference between them, improving the thermal stability and safety of the entire battery cell while reducing production costs. This results in a battery cell with better thermal stability, higher energy density, and higher charging power. Furthermore, since the ternary lithium cells 102 can better control the state of charge (SOC), the accuracy and measurement precision of the overall battery cell's SOC can be improved.

[0050] Please refer to Figure 12 and Figure 13 , Figure 12 This is a graph showing the relationship between open-circuit voltage (OCV) and state of charge (SOC) in lithium iron phosphate (LFP) and ternary lithium battery cells. Open-circuit voltage (OCV) refers to the voltage in the open-circuit state, i.e., when the circuit is open; state of charge (SOC) is the ratio of remaining capacity to the capacity in a fully charged state, with a value of 0 indicating complete discharge and 1 indicating a full charge. Figure 12 It can be seen that in lithium iron phosphate cells, the SOC voltage plateau is very flat from 30% to 95%, while in ternary lithium cells, the SOC curve is steep with a larger slope. The SOC and voltage OCV have an approximately linear relationship, which allows voltage to be used as a better control standard and facilitates calibration. Figure 13 This is a graph showing the voltage versus SOC relationship of a single battery cell in this application. Figure 13 It can be seen that the SOC-OCV curve of the battery cell prepared by the cell assembly of this application is relatively steep and approximately linear, which can better control the SOC and improve the accuracy of the SOC.

[0051] In some embodiments, please refer to Figure 2 , Figure 3 and Figure 4 At least one lithium iron phosphate cell 101 and at least one ternary lithium cell 102 are arranged alternately in series along the second direction Y and / or the third direction Z, with the large side of all lithium iron phosphate cells 101 and ternary lithium cells 102 facing the heat exchanger 20; the first direction X, the second direction Y and the third direction Z are perpendicular to each other.

[0052] It is understood that the second direction Y can be the length direction of the battery cell 1. The third direction Z can be the height direction of the battery cell 1. The arrangement of at least one lithium iron phosphate cell 101 and at least one ternary lithium cell 102 alternately connected in series along the second direction Y and / or the third direction Z can be either an alternating series connection along the second direction Y, or an alternating series connection along the third direction Z, or a simultaneous alternating series connection along the second direction Y and the third direction Z.

[0053] For example, such as Figure 2 As shown, a lithium iron phosphate cell 101 and a ternary lithium battery cell 102 are arranged side by side along the second direction Y. The first negative electrode 1012 of the lithium iron phosphate cell 101 and the second positive electrode 1021 of the ternary lithium battery cell 102 are connected in series through a busbar 103. The first positive electrode 1011 of the lithium iron phosphate cell 101 is electrically connected to the positive terminal 100, and the second negative electrode 1022 of the ternary lithium battery cell 102 is electrically connected to the negative terminal 200.

[0054] Or such as Figure 3 As shown, two rows of lithium iron phosphate cells 101 and ternary lithium cells 101 are alternately arranged along the third direction Z, for example, as shown in the diagram. Figure 3 As shown, to achieve the sequential series connection of lithium iron phosphate cell 101 and ternary lithium cell 102, a ternary lithium cell 102 with a length covering two lithium iron phosphate cells 101 is set at the bottom of the third direction Z. At this time, starting from the left, the first negative electrode 1012 of lithium iron phosphate cell 101 and the second positive electrode 1021 of ternary lithium cell 102 are connected in series through busbar 103. The second negative electrode 1022 of ternary lithium cell 102 is connected to the first positive electrode 1011 of another lithium iron phosphate cell 101, and so on. The first positive electrode 1011 of the top lithium iron phosphate cell 101 is connected to the positive terminal 100, and the first negative electrode 1012 of the other lithium iron phosphate cell 101 is connected to the negative terminal 200.

[0055] Or such as Figure 4As shown, two lithium iron phosphate (LFP) cells 101 are arranged above a ternary lithium battery cell 102 along the third direction Z, and the two LFP cells 101 are arranged side by side along the second direction Y. The first positive tab 1011 of one LFP cell 101 is electrically connected to the positive terminal 100. The first negative tab 1012 of this LFP cell 101 is connected to the second positive tab 1021 of the ternary lithium battery cell 102 via a busbar 103. The second negative tab 1022 of the ternary lithium battery cell 1021 is connected to the first positive tab 1011 of the other LFP cell 101 via a busbar 103. The first negative tab 1012 of this LFP cell 101 is connected to the negative terminal 200. It is understood that the arrangement method of this application is not limited to this; as long as the LFP cells 101 and the ternary lithium battery cells 102 are arranged alternately and connected in series, it is acceptable.

[0056] In the technical solution of this application embodiment, the charging performance and energy density of the overall battery cell are improved by the above settings. The heat exchanger 20 can balance the temperature difference between the lithium iron phosphate cell 101 and the ternary lithium cell 102, making it less likely for the ternary lithium cell 102 to experience thermal runaway, thereby improving the thermal stability and safety of the battery cell and enabling the entire battery cell to have higher charging performance, energy density and safety.

[0057] In some embodiments, please refer to Figure 3 The battery cell assembly 10 includes two rows of lithium iron phosphate cells 101 and ternary lithium cells 102 arranged alternately along the third direction Z. Adjacent lithium iron phosphate cells 101 and ternary lithium cells 102 are connected in series. A ternary lithium cell 102 is disposed at the bottom along the third direction Z, and all lithium iron phosphate cells 101 and ternary lithium cells 102 inside the entire battery cell assembly 10 are connected in series. Or as... Figure 4 The battery cell assembly 10 includes two lithium iron phosphate cells 101 and one ternary lithium battery cell 102. The two lithium iron phosphate cells 101 are arranged side by side along the second direction Y, and the ternary lithium battery cell 102 is arranged below the two lithium iron phosphate cells 101 along the third direction Z, and is connected in series with the two lithium iron phosphate cells 101 alternately. It can be understood that along the second direction Y, the length of the ternary lithium battery cell 102 is the same as the length of the two lithium iron phosphate cells 101.

[0058] In the technical solution of this application embodiment, through the above-described arrangement, because the ternary lithium battery cell 102 has better charging performance and heats up faster, the heat exchange medium in the heat exchanger 20 absorbs heat at the bottom and undergoes a phase change to become gaseous, flowing upward inside the heat exchanger 20. Meanwhile, the lithium iron phosphate battery cell 101, located at the top, has a relatively lower temperature, and the heat exchange medium, upon cooling, transforms into a liquid state and returns to the bottom under its own gravity. The heat exchange medium circulates repeatedly within the heat exchanger 20 to balance the temperature difference between the battery cells, improving the thermal stability and safety of the battery cells. This reduces the likelihood of thermal runaway in the ternary lithium battery cell 102. Furthermore, at low temperatures, the heating characteristics of the ternary lithium battery cell 102 can be utilized to quickly raise the temperature of the lithium iron phosphate battery cell 101, improving its low-temperature stability.

[0059] In some embodiments, please refer to Figure 8 , Figure 9 and Figure 10 The heat exchanger 20 is a plate heat pipe, and the heat exchanger 20 has a flow channel 201 inside that allows the phase change medium to flow, so that the phase change medium can exchange heat with the large surface side of the lithium iron phosphate battery cell 101 and the ternary lithium battery cell 102 respectively. In some embodiments, the plate heat pipe can transfer heat through the vapor-liquid phase change of the internal phase change medium, with low thermal resistance and high thermal conductivity.

[0060] It is understandable that a plate heat pipe is a type of heat exchanger plate, an independently sealed component. A liquid phase change medium with negative pressure is injected inside the plate heat pipe. Its working mode is as follows: the internal medium is heated and evaporates, absorbing heat and turning into a gaseous state. It then cools at the location of the lithium iron phosphate cell 101, turning back into a liquid state. It moves downwards under gravity, is heated again, and this process is repeated continuously to achieve temperature uniformity.

[0061] In some embodiments, such as Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the lithium iron phosphate battery cell 101 includes a first positive tab 1011 and a first negative tab 1012, and the ternary lithium battery cell 102 includes a second positive tab 1021 and a second negative tab 1022. The first negative tab 1012 of the lithium iron phosphate battery cell 101 and the second positive tab 1021 of the ternary lithium battery cell 102 are connected in series through a busbar 103, or the first positive tab 1011 of the lithium iron phosphate battery cell 101 and the second negative tab 1022 of the ternary lithium battery cell 102 are connected in series through a busbar 103.

[0062] In the technical solution of this application embodiment, the above settings enable the series electrical connection between adjacent lithium iron phosphate cells 101 and ternary lithium cells 102.

[0063] In some embodiments, please refer to Figure 1 and Figure 6 The battery cell also includes a positive electrode post 100 and a negative electrode post 200. The positive electrode post 100 is connected to the first positive tab 1011 of one of the lithium iron phosphate cells 101 or to the second positive tab 1021 of one of the ternary lithium cells 102. The negative electrode post 200 is connected to the first negative tab 1012 of one of the lithium iron phosphate cells 101 or to the second negative tab 1022 of one of the ternary lithium cells 102.

[0064] In the technical solution of this application embodiment, the above settings are used to realize the electrical connection between the cell assembly 10 composed of lithium iron phosphate cell 101 and ternary lithium cell 102 and the positive terminal 100 and negative terminal 200 on the end cap.

[0065] In some embodiments, please refer to Figure 7 The battery cell also includes an insulating film 30, which covers the outside of the cell assembly 10.

[0066] In the technical solution of this application embodiment, by covering the outside of the cell assembly 10 with the insulating film 30, the cell assembly 10 is insulated from the casing, thereby improving the safety of the battery cell.

[0067] In some embodiments, please refer to Figure 7 The battery cell also includes a housing 40 with a receiving cavity 401, the cell assembly 10 is disposed in the receiving cavity 401, and the heat exchanger 20 is disposed between the insulating film 30 and the cavity wall of the receiving cavity 401.

[0068] On the other hand, this application also provides a battery pack, such as Figure 11 As shown, the device includes a housing 2 and multiple battery cells 1, which are arranged sequentially within the housing 2 along a first direction X. These battery cells 1 are then assembled into a battery pack. The battery pack employs a battery cell structure that alternates between lithium iron phosphate cells and ternary lithium cells connected in series, resulting in better thermal stability, higher energy density, and higher charging power. The first direction X can be the thickness direction of the battery cell 1.

[0069] On the other hand, this application also provides an electrical device including the battery pack described in the second aspect.

[0070] Electrical devices can include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: A battery cell assembly (10) includes at least one lithium iron phosphate battery cell (101) and at least one ternary lithium battery cell (102), wherein the lithium iron phosphate battery cell (101) and the ternary lithium battery cell (102) are connected in series alternately in sequence. A heat exchanger (20) is disposed along a first direction (X) on at least one large surface side of the cell assembly (10) and covers the large surface side of all the lithium iron phosphate cells (101) and the ternary lithium cells (102).

2. The battery cell according to claim 1, characterized in that, At least one lithium iron phosphate cell (101) and at least one ternary lithium cell (102) are arranged alternately in series along a second direction (Y) and / or a third direction (Z), with the large facet of all the lithium iron phosphate cells (101) and the ternary lithium cells (102) facing the heat exchanger (20); the first direction (X), the second direction (Y) and the third direction (Z) are perpendicular to each other.

3. The battery cell according to claim 2, characterized in that, The battery cell assembly (10) includes two lithium iron phosphate cells (101) and one ternary lithium battery cell (102). The two lithium iron phosphate cells (101) are arranged side by side along the second direction (Y). The ternary lithium battery cell (102) is arranged below the two lithium iron phosphate cells (101) along the third direction (Z) and is connected in series with the two lithium iron phosphate cells (101) alternately.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The lithium iron phosphate battery cell (101) includes a first positive electrode (1011) and a first negative electrode (1012), and the ternary lithium battery cell (102) includes a second positive electrode (1021) and a second negative electrode (1022). The first negative electrode (1012) of the lithium iron phosphate battery cell (101) and the second positive electrode (1021) of the ternary lithium battery cell (102) are connected in series through a busbar (103), or the first positive electrode (1011) of the lithium iron phosphate battery cell (101) and the second negative electrode (1022) of the ternary lithium battery cell (102) are connected in series through a busbar (103).

5. The battery cell according to claim 1, characterized in that, The heat exchanger (20) is a plate heat pipe. The heat exchanger (20) has a flow channel (201) inside that allows the phase change medium to flow, so that the phase change medium can exchange heat with the large surface side of the lithium iron phosphate battery cell (101) and the ternary lithium battery cell (102).

6. The battery cell according to claim 4, characterized in that, Also includes: The positive electrode post (100) is connected to the first positive electrode tab (1011) of one of the lithium iron phosphate cells, or to the second positive electrode tab (1021) of one of the ternary lithium cells (102); The negative electrode post (200) is connected to the first negative electrode tab (1012) of one of the lithium iron phosphate cells, or to the second negative electrode tab (1022) of one of the ternary lithium cells (102).

7. The battery cell according to claim 1, characterized in that, Also includes: An insulating film (30) is wrapped around the outside of the battery cell assembly (10).

8. The battery cell according to claim 7, characterized in that, Also includes The housing (40) has a receiving cavity (401), the battery cell assembly (10) is disposed in the receiving cavity (401), and the heat exchanger (20) is disposed between the insulating film (30) and the cavity wall of the receiving cavity (401).

9. A battery pack, characterized in that, include: Box (2), and The battery cell (1) according to any one of claims 1 to 8, wherein the battery cells (1) are arranged sequentially in the housing (2) along a first direction (X).

10. An electrical device, characterized in that, Includes the battery pack as described in claim 9.

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