Battery module, battery device and electric equipment

Abstract

The utility model discloses a battery module, a battery device and electric equipment, the battery module comprises a plurality of batteries which are sequentially arranged along a first direction, and each battery comprises a shell; the shell comprises a first shell body and a second shell body, the batteries located at the two ends of the outermost side in the first direction are provided with the first shell body, at least one battery located between the two ends of the outermost side in the first direction is provided with the second shell body, and the heat conduction capacity of the first shell body is smaller than that of the second shell body. The temperature distribution of the battery cells of the battery module is uniform.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and in particular to a battery module, a battery device and electrical equipment. Background Art

[0002] The shell material of the battery cells in the battery module is aluminum. In a low-temperature environment, the outermost battery of the battery module conducts heat to the external low-temperature environment first, and the temperature of the outermost battery of the battery module is lower than that of the other batteries. When the battery module is in use, the temperature of the batteries on the outside of the battery module is lower because the batteries on the outermost layer of the battery module have better heat dissipation. However, the temperature of the outermost battery of the battery module is still lower than that of the batteries in the middle area.

[0003] Uneven battery temperatures in various areas of a battery module may affect the overall performance of the battery device, reducing the service life and charging efficiency of the battery device. Utility Model Content

[0004] The utility model aims to provide a battery module, a battery device and an electric equipment to solve the problem of uneven temperature of battery cells in the battery module.

[0005] In order to achieve the purpose of the utility model, the utility model provides the following technical solutions:

[0006] In a first aspect, the utility model provides a battery module, the battery module comprising a plurality of batteries arranged in sequence along a first direction, each of the batteries comprising a housing;

[0007] The shell includes a first shell and a second shell, the batteries located at the two outermost ends in the first direction have the first shell, and at least one of the batteries located between the two outermost ends in the first direction has the second shell, and the thermal conductivity of the first shell is smaller than the thermal conductivity of the second shell.

[0008] In one implementation, the number of the batteries having the first shell on the outermost sides in the first direction is n, satisfying: 1≤n≤3, where n is a positive integer.

[0009] In one implementation, the thermal conductivity of the first shell is a1, and the thermal conductivity of the second shell is a2, satisfying: a1<a2.

[0010] In one implementation manner, the thermal conductivity a1 of the first shell and the thermal conductivity a2 of the second shell further satisfy: 4≤a2 / a1≤6.

[0011] In one implementation, the wall thickness of the first shell is d1, satisfying: 0.1 mm≤d1≤0.15 mm.

[0012] In one implementation, the wall thickness of the second shell is d2, satisfying: 0.2mm≤d2≤0.5mm.

[0013] In one embodiment, the first shell is a steel shell, and the second shell is an aluminum shell.

[0014] In a second aspect, the utility model provides a battery device, comprising a tray and a battery module according to any one of various embodiments of the first aspect, wherein the tray encloses a receiving space, and the battery module is received in the receiving space.

[0015] In one embodiment, the tray includes a frame and a connecting beam, the frame encloses the receiving space, the connecting beam is connected to the frame and divides the receiving space into a plurality of sub-spaces, and each sub-space corresponds to receiving one battery module.

[0016] In one implementation, the dimension of the battery device in the first direction is L1, which satisfies: 1m≤L1≤2.5m.

[0017] In one embodiment, the dimension of the battery device in the second direction is L2, which satisfies: 1m≤L2≤2.5m.

[0018] In a third aspect, the utility model provides an electrical device, comprising an electrical device and a battery device as described in any one of various embodiments of the second aspect, wherein the battery device supplies power to the electrical device.

[0019] The battery module of the utility model is provided with a plurality of batteries arranged in sequence in a first direction, and the battery shell includes a first shell and a second shell, wherein the thermal conductivity of the first shell is smaller than the thermal conductivity of the second shell, and the battery including the first shell is arranged at the outermost side of the plurality of batteries in the first direction. The battery including the first shell arranged at the outermost side can serve as a heat-insulating structural member of the battery module, thereby reducing the temperature difference between the batteries located in the edge area and the batteries located in the middle area of ​​the battery module, and improving the phenomenon of uneven temperature of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a top view of a battery device according to an embodiment;

[0022] Figure 2 is a cross-sectional view of a battery device according to an embodiment.

[0023] Description of reference numerals:

[0024] 100 -battery device, 10 -battery module, 11 -shell, 111 -first shell, 112 -second shell, 12 -battery cell, 20 -tray, 21 -frame, 211 -first plate, 212 -second plate, 22 -connecting beam, 221 -first beam, 222 -second beam, X -first direction, Y -second direction. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there can be a central component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there can be a central component at the same time.

[0027] Unless otherwise defined, all technical and scientific terms used in this utility model have the same meaning as those commonly understood by technicians in the technical field of this utility model. The terms used in the specification of this utility model are only for the purpose of describing specific embodiments and are not intended to limit this utility model. The term "and / or" used in this utility model includes any and all combinations of one or more related listed items.

[0028] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] For reference Figure 1 The utility model provides a battery module 10, which includes a plurality of batteries arranged in sequence along a first direction X, and each battery includes a shell 11. The shell 11 includes a first shell 111 and a second shell 112, the batteries located at the two outermost ends in the first direction X have the first shell 111, and at least one battery located between the two outermost ends in the first direction X has the second shell 112, and the thermal conductivity of the first shell 111 is smaller than that of the second shell 112.

[0030] The size of the battery in the first direction X is the thickness of the battery. The thickness of the battery is a1, which satisfies: 10 mm ≤ a1 ≤ 25 mm. Specifically, a1 can be 10 mm, 15 mm, 20 mm, 25 mm, etc., without limitation.

[0031] The dimension of the battery in the second direction Y is the length of the battery, and the length of the battery is a2, which satisfies: 500mm≤a2≤960mm. Specifically, a2 can be 500mm, 600mm, 700mm, 800mm, 900mm, 960mm, etc., without limitation.

[0032] The dimension of the battery in the third direction is the height of the battery. The height of the battery is a3, which satisfies: 90mm≤a3≤135mm. Specifically, a3 can be 90mm, 100mm, 110mm, 120mm, 130mm, 135mm, etc., without limitation.

[0033] The first direction X, the second direction Y and the third direction intersect each other.

[0034] The battery includes a shell 11 and a battery cell 12. The length, height and width of the batteries with different shells 11 are the same, which is convenient for assembling the battery module 10. The battery of the utility model can be a square battery, a round battery, a soft pack battery, etc. Optionally, the battery is a blade battery among square batteries. The blade battery has high packaging reliability, high volume utilization, and good heat dissipation performance, which effectively increases the space utilization of the battery device 100 and improves the energy density of the battery device 100. The battery includes a first battery and a second battery. The first battery is a battery whose shell 11 is a first shell 111, and the second battery is a battery whose shell 11 is a second shell 112.

[0035] In one embodiment, except for the first batteries at the two outermost ends in the first direction X, the remaining batteries of the battery module 10 are all second batteries.

[0036] In one embodiment, except for the first batteries at the two outermost ends in the first direction X, the first batteries and the second batteries in the battery module 10 are arranged alternately. Specifically, the first batteries and the second batteries are arranged in an array, or the first batteries and the second batteries are arranged randomly.

[0037] For reference Figure 2 The battery cell 12 includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet is usually made of materials such as lithium compounds and lithium cobalt oxide, while the negative electrode sheet is usually made of carbon materials such as graphite. During the charging and discharging process, lithium ions move back and forth between the two electrodes to complete the conversion and storage of electrical energy. Corresponding terminals are provided on the positive and negative electrodes of the battery cell 12 for connection. The positive and negative terminals of two adjacent battery cells 12 are electrically connected to realize the series connection of the batteries.

[0038] The electrical connection of the battery can be welding connection, screw connection, plug connection, etc., without limitation. Specifically, the positive and negative terminals of the battery are welded to the connecting piece or wire by spot welding equipment to form a reliable electrical connection. The welding method can be brazing, arc welding, laser welding, ultrasonic welding, etc.

[0039] Any two batteries are connected by a connector, which may be a connector sheet, a connector bar, a wire, etc., without limitation. Specifically, the connector bar may be a copper bar, an aluminum bar, etc., without limitation. The connector bar can realize electrical connection between batteries, thereby forming the required series and parallel relationship. The connection between the connector bar and the battery may be welding, bonding, etc. Specifically, welding is more secure and has a small connection resistance. The connector bar is arranged at the end of the battery in the second direction Y.

[0040] Optionally, the heat conductivity of the shell is related to the wall thickness of the shell and the thermal conductivity of the shell.

[0041] Specifically, when the wall thickness of the first shell 111 is the same as that of the second shell 112 , the thermal conductivity of the first shell 111 is smaller than that of the second shell 112 , and the thermal conductivity of the first shell 111 is smaller than that of the second shell 112 .

[0042] Specifically, when the thermal conductivity of the first shell 111 is the same as that of the second shell 112 , the wall thickness of the first shell 111 is greater than that of the second shell 112 , and the thermal conductivity of the first shell 111 is less than that of the second shell 112 .

[0043] When the wall thickness and thermal conductivity of the first shell 111 and the second shell 112 are different, they need to be adjusted according to actual conditions to achieve that the thermal conductivity of the first shell 111 is smaller than that of the second shell 112 .

[0044] The battery module 10 of the utility model is provided with a plurality of batteries arranged in sequence in a first direction X, and the battery shell 11 includes a first shell 111 and a second shell 112, the thermal conductivity of the first shell 111 is less than the thermal conductivity of the second shell 112, and the battery including the first shell 111 is arranged at the outermost side of the plurality of batteries in the first direction X, and the battery including the first shell 111 can serve as a heat preservation structural member of the battery module 10 at the outermost side, reduce the temperature difference between batteries in different areas of the battery module 10, and improve the temperature unevenness of the battery module 10. The first battery in the outermost layer serves as a heat preservation structural member of the battery module 10, which can reduce the cost of the corresponding structural members for heat preservation of the battery in the battery module 10, and can reduce the production cost of the battery module 10 while also achieving the lightweight of the battery module 10.

[0045] In addition, the thermal conductivity of the first shell 111 is poor. When the first battery in the battery module 10 has thermal runaway, the heat generated by it will be slowly transferred to the adjacent second battery, delaying the thermal diffusion time of the battery in the battery module 10; and when the second battery has thermal runaway, the time for the adjacent first battery to receive heat and cause thermal runaway will also be extended.

[0046] In one implementation, the number of batteries with the first shell 111 on the outermost side in the first direction X is n, satisfying: 1≤n≤3, where n is a positive integer.

[0047] Specifically, n can be 1, 2, or 3.

[0048] When n is less than 1, there is no battery with the first shell 111 on the outermost side. The thermal conductivity of the outermost battery and the battery in the middle is the same, but the outermost battery conducts or dissipates heat first to the outside, so that the temperature of the outermost battery is lower than that of the battery in the middle area, resulting in uneven temperature distribution of the batteries in the battery module 10. When n is greater than 3, there are too many batteries with the first shell 111 on the outermost side, resulting in poor overall heat dissipation performance of the battery module 10, uniform temperature distribution of the battery module 10 but high temperature of the battery module 10. The high temperature of the battery module 10 will reduce the life of the battery, and thermal runaway phenomena such as spontaneous combustion and explosion of the battery may also occur. When 1≤n≤3, the number of batteries with the first shell 111 on the outermost side of the battery module 10 is appropriate, which can not only make the temperature distribution of the battery module 10 uniform, but also ensure the heat dissipation performance of the battery module 10.

[0049] In one implementation, the thermal conductivity of the first shell 111 is a1, and the thermal conductivity of the second shell 112 is a2, satisfying: a1<a2.

[0050] In one implementation, the thermal conductivity a1 of the first shell 111 and the thermal conductivity a2 of the second shell 112 further satisfy: 4≤a2 / a1≤6.

[0051] a2 / a1 can be 4, 4.5, 5, 5.5, 6, etc. without limitation.

[0052] The first shell 111 may be a steel shell, a ceramic shell, polycarbonate (PC), etc., and the second shell 112 may be an aluminum shell or a copper shell.

[0053] When a2 / a1<4, the difference in thermal conductivity between the first shell 111 and the second shell 112 is small, the difference in heat dissipation performance between the first battery on both sides in the first direction X and the second battery in the remaining area is small, and the difference in heat dissipation performance between the first shell 111 and the second shell 112 cannot offset the temperature difference caused by the difference in battery position, and the temperature of the batteries on both sides in the first direction X may be lower than the temperature of the batteries in the remaining area; when a2 / a1>6, the difference in thermal conductivity between the first shell 111 and the second shell 112 is large, the difference in heat dissipation performance between the first battery on both sides and the second battery in the remaining area is large, and the difference in heat dissipation performance between the first shell 111 and the second shell 112 is greater than the temperature difference caused by the difference in battery position, showing that the temperature of the first battery on both sides in the first direction X is higher than the temperature of the batteries in the remaining area; when 4≤a2 / a1≤6, the difference in heat dissipation performance between the first shell 111 and the second shell 112 can offset the temperature difference caused by the difference in battery position, thereby improving the phenomenon of uneven temperature of the battery module 10.

[0054] In one implementation, the wall thickness of the first shell 111 is d1, which satisfies: 0.1 mm≤d1≤0.15 mm.

[0055] Specifically, when the thermal conductivity a1 of the first shell 111 is less than the thermal conductivity a2 of the second shell 112, that is, the materials of the first shell 111 and the second shell 112 are different, the first shell 111 is arranged outside the battery module 10, and it is necessary to ensure that the first shell 111 has a certain structural strength to protect the battery cell 12. On the other hand, in order to improve the capacity density of the battery, the wall thickness of the first shell 111 can be set to d1, 0.1mm≤d1≤0.15mm. d1 can be 0.1mm, 0.12mm, 0.14mm, 0.15mm, etc., without limitation.

[0056] It can be understood that when d1 is less than 0.1mm, the first shell 111 has a poor protective effect on the battery cell 12; when d1 is greater than 0.15mm, due to the low thermal conductivity of the first shell 111, if the wall thickness of the first shell 111 is too large, the heat dissipation performance of the first battery will be further weakened, increasing the risk of thermal runaway of the first battery. In addition, under the premise of ensuring the structural strength of the first shell 111, setting the wall thickness too large will reduce the energy density of the battery; when 0.1mm≤d1≤0.15mm, the first shell 111 can make the heat dissipation performance of the first battery good while having a good protective effect on the battery cell 12, and can also improve the energy density of the battery module 10.

[0057] In one implementation, the wall thickness of the second shell 112 is d2, satisfying: 0.2 mm ≤ d2 ≤ 0.5 mm.

[0058] Specifically, when the thermal conductivity a1 of the first shell 111 is less than the thermal conductivity a2 of the second shell 112, the materials of the first shell 111 and the second shell 112 are different. Usually, the second shell 112 is an aluminum shell or other materials with good thermal conductivity. In order to ensure the structural strength of the second shell 112, the manufacturing process of the aluminum shell also needs to be considered. The wall thickness of the second shell 112 can be set to d2, 0.2mm≤d2≤0.5mm. d2 can be 0.2mm, 0.3m, 0.4mm, 0.5mm, etc., without limitation.

[0059] It is understandable that when d2 is less than 0.2mm, the second shell 112 has a poor protective effect on the battery cell 12. Optionally, the aluminum shell usually has good thermal conductivity but a weak structure. When the thickness of the second shell 112 is set to be less than 0.2mm, it may cause the structural strength of the second shell 112 to be difficult to meet the supporting and protective effects on the battery cell 12. The manufacturing process of the aluminum shell also needs to be considered, so d2>0.2mm; when d2>0.5mm, the wall thickness of the second shell 112 is too large, which will affect the heat dissipation performance of the second battery, while reducing the space utilization of the battery module 10 and increasing the production cost of the second shell 112; when 0.2mm≤d2≤0.5mm, the second shell 112 can make the second battery have good heat dissipation performance while having a good protective effect on the battery cell 12. Taking into account the current common shells using aluminum shells, aluminum shell manufacturing process and other factors, preferably, d2 satisfies: 0.2mm≤d2≤0.5mm.

[0060] Specifically, under the premise of ensuring the structural strength of the first shell 111 and the second shell 112, when 4≤a2 / a1≤6, and the wall thickness d1 of the first shell 111 satisfies: 0.1mm≤d1≤0.15mm, and the wall thickness d2 of the second shell 112 satisfies: 0.2mm≤d2≤0.5mm, the thermal conductivity of the first shell 111 can be less than that of the second shell 112 when the wall thickness and thermal conductivity of the first shell 111 and the second shell 112 are different.

[0061] In one embodiment, the first shell 111 is a steel shell, and the second shell 112 is an aluminum shell.

[0062] Specifically, the thermal conductivity of the steel shell is the first thermal conductivity a1, a1 is 45W / mK, the thermal conductivity of the aluminum shell is the second thermal conductivity a2, a2 ​​is 235W / mK, and the ratio of a2 / a1 is 5.2, satisfying: 4≤a2 / a1≤6. The outermost battery in the first direction X is a steel shell battery, which acts as a thermal insulation layer of the battery module 10, reducing the temperature difference between batteries in different areas and reducing the cost of the corresponding structural parts for thermal insulation of the batteries in the battery module 10; and the thermal conductivity of the steel shell is poor, and the time for the heat generated by the thermal runaway of the steel shell battery to be transmitted to the adjacent aluminum shell battery will increase. Correspondingly, the time for the heat generated by the thermal runaway of the aluminum shell battery to be transmitted to the adjacent steel shell battery will also increase, delaying the diffusion time of the battery in the battery module 10 after thermal runaway. Although the wall thickness of the steel shell battery is smaller than that of the aluminum shell battery, the steel shell battery can still maintain good structural strength.

[0063] For reference Figure 1 and Figure 2 The utility model provides a battery device 100, including a tray 20 and the battery module 10 described in any of the above embodiments, the tray 20 encloses a receiving space, and the battery module 10 is received in the receiving space.

[0064] The tray 20 is used to support and fix the battery module 10. The tray 20 is usually made of metal or plastic materials, wherein metal materials such as aluminum alloy and stainless steel have high strength and corrosion resistance, and are suitable for battery systems under high load and harsh environment. Plastic materials such as nylon, polycarbonate, fiberglass, etc. have light weight and good insulation performance, and are suitable for some application scenarios with high requirements on weight and cost.

[0065] For reference Figure 1 and Figure 2 In one embodiment, the tray 20 includes a frame and a connecting beam 22 . The frame encloses the receiving space. The connecting beam 22 is connected to the frame and divides the receiving space into a plurality of sub-spaces. Each sub-space corresponds to receiving a battery module 10 .

[0066] Adjacent battery modules 10 are provided with connection bars, etc., to achieve series or parallel connection of the battery modules 10 .

[0067] The frame and the connecting beam 22 may be an integrated structure, that is, the frame and the connecting beam 22 are an integrated structure prepared by an integrated process, and the integrated process may be casting, stamping, etc., without limitation. The frame and the connecting beam 22 may be a split structure, that is, the connection method of the frame and the connecting beam 22 may be screw connection, welding, clamping, bonding, etc.

[0068] The connecting beam 22 includes a first beam 221 extending in the first direction X and a second beam 222 extending in the second direction Y, the frame includes a first plate 211 extending in the first direction X and a second plate 212 extending in the second direction Y, and the first shell 111 of the first battery on the outermost side of the battery module 10 in the first direction X is tightly attached to the second beam 222 or the second plate 212, thereby fixing the battery module 10, which is beneficial to the structural stability of the battery device 100.

[0069] The frame and the connecting beam 22 divide the receiving space into multiple subspaces, so that the battery device 100 can accommodate multiple battery modules 10, which is conducive to improving the modular design of the battery device 100 and facilitating the replacement, maintenance and upgrading of the battery module 10. At the same time, the modular structure also facilitates the heat dissipation design and thermal management of the battery device 100.

[0070] In one implementation, the dimension of the battery device 100 in the first direction X is L1, which satisfies: 1 m≤L1≤2.5 m.

[0071] L1 can be 1m, 1.2m, 1.5m, 2m, 2.5m, etc. without restriction.

[0072] When L1 is less than 1 m, the number of batteries arranged in the first direction X of the battery device 100 is small, and the energy density per unit volume of the battery device 100 is low; when L1 is greater than 2.5 m, the number of battery modules 10 arranged in the first direction X of the battery device 100 is too large, or the number of batteries in the battery module 10 in the first direction X is too large, and the battery device 100 is more likely to generate heat during charging and use. If the heat dissipation is poor, there may be a risk of overheating or even fire, and a large-sized battery device 100 may be more easily damaged when impacted or squeezed, resulting in internal short circuit or leakage of the battery; when 1 m ≤ L1 ≤ 2.5 m, the battery device 100 reduces the risk of thermal runaway while ensuring the energy density.

[0073] In one implementation, the dimension of the battery device 100 in the second direction Y is L2, which satisfies: 1 m≤L2≤2.5 m.

[0074] L2 can be 1m, 1.2m, 1.5m, 2m, 2.5m, etc. without restriction.

[0075] When L2 is less than 1m, the number of battery modules 10 arranged in the second direction Y of the battery device 100 is small, and the energy density per unit volume of the battery device 100 is low; when L2 is greater than 2.5m, the number of battery modules 10 arranged in the second direction Y of the battery device 100 is large, and the battery device 100 is more likely to generate heat during charging and use. If the heat dissipation is poor, there may be a risk of overheating or even fire, and a large-sized battery device 100 may be more easily damaged when impacted or squeezed, resulting in internal short circuit or leakage of the battery; when 1m≤L2≤2.5m, the battery device 100 reduces the risk of thermal runaway while ensuring the energy density.

[0076] The battery device 100 of the utility model is provided with at least one battery module 10, and the battery of the battery module 10 is provided with a first shell 111 and a second shell 112, and the battery of the first shell 111 with a relatively small thermal conductivity is arranged at the outermost side of the plurality of batteries in the first direction X, and the battery including the first shell 111 can serve as a heat preservation structural member of the battery module 10 at the outermost side, reduce the temperature difference between the battery located in the edge area and the battery located in the middle area of ​​the battery module 10, and improve the temperature unevenness of the battery module 10. The outermost first battery serves as a heat preservation structural member of the battery module 10, which can reduce the cost of the corresponding structural members for heat preservation of the battery in the battery device 100, and is conducive to the lightweighting of the battery device 100. And the poor thermal conductivity of the first shell 111 is conducive to delaying the heat diffusion time after the thermal runaway of the battery device 100 occurs.

[0077] The utility model provides an electric device, including an electric device and the battery device 100 described in any of the above embodiments, the battery device 100 supplies power to the electric device. The electric device can be a washing machine, a television, etc., and the electric device can be a transformer, a light bulb, etc., without limitation.

[0078] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientation or positional relationship described in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0079] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A battery module, characterized in that: It comprises a plurality of batteries arranged in sequence along a first direction, each of the batteries comprising a housing; The shell includes a first shell and a second shell, the batteries located at the two outermost ends in the first direction have the first shell, and at least one of the batteries located between the two outermost ends in the first direction has the second shell, and the thermal conductivity of the first shell is smaller than the thermal conductivity of the second shell.

2. The battery module according to claim 1, characterized in that: The number of the batteries with the first shell on the outermost sides in the first direction is n, satisfying: 1≤n≤3, where n is a positive integer.

3. The battery module according to claim 1, characterized in that: The thermal conductivity of the first shell is a1, and the thermal conductivity of the second shell is a2, which satisfies: a1<a2.

4. The battery module according to claim 3, characterized in that: The thermal conductivity a1 of the first shell and the thermal conductivity a2 of the second shell further satisfy: 4≤a2 / a1≤6.

5. The battery module according to claim 4, characterized in that: The wall thickness of the first shell is d1, which satisfies: 0.1 mm≤d1≤0.15 mm.

6. The battery module according to claim 5, characterized in that: The wall thickness of the second shell is d2, which satisfies: 0.2mm≤d2≤0.5mm.

7. The battery module according to claim 4, characterized in that: The first shell is a steel shell, and the second shell is an aluminum shell.

8. A battery device, characterized in that: It comprises a tray and the battery module according to any one of claims 1 to 7, wherein the tray encloses a receiving space, and the battery module is received in the receiving space.

9. The battery device according to claim 8, characterized in that: The tray includes a frame and a connecting beam. The frame encloses the receiving space. The connecting beam is connected to the frame and divides the receiving space into a plurality of subspaces. Each subspace receives one battery module.

10. The battery device according to claim 8, characterized in that: The dimension of the battery device in the first direction is L1, which satisfies: 1m≤L1≤2.5m.

11. The battery device according to claim 8, characterized in that: The dimension of the battery device in the second direction is L2, which satisfies: 1m≤L2≤2.5m.

12. An electrical device, characterized in that: The invention comprises an electric device and a battery device as claimed in any one of claims 8 to 11, wherein the battery device supplies power to the electric device.

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