A thermal equalization cell

Abstract

This invention provides a thermally balanced battery cell, comprising a housing and a wound battery cell. The wound battery cell is disposed within the housing and includes a first wound battery cell and a second wound battery cell arranged coaxially. A heat-conducting wall is disposed between the first and second wound battery cells, and a heat-conducting column is coaxially disposed within the first wound battery cell. By coaxially arranging the first and second wound battery cells within the housing and providing a circumferentially connected, annularly closed heat-conducting wall extending axially between them, this invention creates a stable radial heat-conducting channel within the wound battery cell. The coaxially arranged heat-conducting column can quickly dissipate heat from the central area with the worst heat dissipation conditions in a traditional wound battery cell and forms a synergistic heat-conducting structure with the annular heat-conducting wall, thereby further reducing the temperature gradient inside the battery cell and achieving a balanced distribution of overall heat.

Description

Technical Field

[0001] This invention relates to the technical field of lithium-ion battery cells, and particularly to a thermally balanced aluminum-cased wound battery cell. Background Technology

[0002] With the rapid development of new energy storage systems, electric vehicles, and high-power electrical equipment, aluminum-cased wound lithium-ion cells have been widely used in these fields due to their outstanding advantages such as high structural strength, excellent space utilization, and adaptability to modular integration. The existing structure of aluminum-cased wound lithium-ion cells typically involves winding the electrode sheets, inserting them into a metal casing, and then encapsulating them. During normal operation, the electrochemical reactions and internal resistance losses within the cell continuously generate heat. However, due to the inherent characteristics of the wound structure, the electrode layers are unevenly distributed, resulting in a long heat conduction path. Furthermore, the heat conduction through the metal casing exhibits significant directional differences. These factors combined lead to significant differences in the temperature rise rate and steady-state temperature across different regions within the cell, making it easy for heat to accumulate in localized areas and hindering the achievement of balanced heat control across the entire cell.

[0003] The aforementioned technical defects related to uneven heat distribution are particularly pronounced under conditions of high-rate charging and discharging or long-term continuous operation of the battery cell. Localized overheating not only accelerates the aging of electrode active materials, electrolyte decomposition, and separator performance degradation, but can also lead to a series of problems such as abnormally increased internal resistance and inconsistent capacity decay, ultimately resulting in a shortened cycle life and decreased consistency of the battery cell. In extreme cases, excessive accumulation of localized heat can even induce thermal runaway, significantly reducing the safety margin of the battery system and thus hindering the further promotion and application of aluminum-cased wound lithium-ion cells in high-energy-density and high-power-density applications. Therefore, developing a technical solution that can effectively disperse and evenly control internal heat within aluminum-cased wound lithium-ion cells, considering their structural characteristics, has become a crucial technical challenge that urgently needs to be addressed in this field. Solving this technical challenge has significant engineering application value and practical significance for improving the safety, reliability, and lifespan of aluminum-cased wound lithium-ion cells. Summary of the Invention

[0004] To address some of the aforementioned problems, this invention provides a thermally balanced battery cell, comprising a housing and a wound battery cell. The wound battery cell is disposed within the housing and includes a first wound battery cell and a second wound battery cell coaxially arranged. The inner diameter of the first wound battery cell is larger than the outer diameter of the second wound battery cell. A heat-conducting wall is disposed between the first and second wound battery cells. The heat-conducting wall is a circumferentially connected annular closed structure, extending axially along the wound battery cell and contacting the bottom of the thermally balanced battery cell. The heat-conducting wall is insulated from the top of the thermally balanced battery cell; the inner diameter of the heat-conducting wall is more than 1% larger than the outer diameter of the second wound battery cell, and the outer diameter of the heat-conducting wall is more than 1% smaller than the inner diameter of the first wound battery cell; a heat-conducting pillar is coaxially arranged at the center of the first wound battery cell, and the outer diameter of the heat-conducting pillar is more than 1% smaller than the inner diameter of the second wound battery cell; the top is insulated with positive and negative electrodes, and the two ends of the heat-conducting pillar are in contact with the bottom and / or the top; or, the top is insulated from the outer casing, and the heat-conducting pillar is insulated from the top. Insulation can be achieved by leaving a gap between the two components or by using insulating material between the two components.

[0005] The thermally balanced battery cell of the present invention coaxially arranges a first wound battery cell and a second wound battery cell within a housing, and sets a circumferentially connected, annularly closed heat-conducting wall extending axially between the two, thereby forming a stable radial heat-conducting channel inside the wound battery cell. Because the heat-conducting wall is a continuous closed structure, it can uniformly collect the heat generated by the second wound battery cell in the circumferential direction and guide the heat axially to the bottom of the battery cell, thus avoiding localized heat accumulation inside the wound battery cell and effectively improving the problem of uneven temperature distribution in the radial and circumferential directions of the battery cell.

[0006] Furthermore, by setting the inner diameter of the heat-conducting wall to be 1% greater than the outer diameter of the second wound cell and setting the outer diameter of the heat-conducting wall to be less than 1% greater than the inner diameter of the first wound cell, a radial gap with a clear threshold significance is formed between the heat-conducting wall and the wound cell. The inventors found that when the radial gap is less than 1%, the gap is easily offset or even disappears under the superposition of assembly tolerance, cell thermal expansion and cyclic deformation, resulting in close contact between the heat-conducting wall and the wound cell, which leads to unstable thermo-mechanical coupling effect and difficulty in continuously playing a decoupling role; while when the radial gap reaches 1% or more, the gap can exist stably under long-term charge-discharge cycles and temperature change conditions, providing reliable release space for the radial "breathing expansion" of the wound cell, and avoiding the heat-conducting wall from forming a continuous mechanical constraint on the wound cell, thereby achieving no interference between the thermal conduction function and the structural mechanical behavior, which is conducive to maintaining the consistency of thermal management effect and structural reliability of the cell during long-term operation.

[0007] Furthermore, a heat-conducting pillar is coaxially positioned at the center of the first wound cell, with both ends of the pillar contacting the bottom and / or top of the cell, providing a direct axial heat-conducting path to the central region of the wound cell. This structure enables rapid heat dissipation from the central region, where heat dissipation conditions are worst in traditional wound cells, and forms a synergistic heat-conducting structure with the annular heat-conducting wall, thereby further reducing the temperature gradient inside the cell and achieving a balanced distribution of overall heat.

[0008] By combining a coaxial double-wound battery cell, a circumferentially enclosed heat-conducting wall, and a central heat-conducting column, this invention constructs a multi-channel heat-conducting structure that combines radial and axial heat conduction within a single battery cell. This allows the heat generated by the battery cell under high-rate or long-term operating conditions to be evenly distributed and promptly dissipated, thereby effectively reducing the risk of local overheating and improving the safety, cycle life, and consistency of the battery cell when used in groups.

[0009] In one embodiment of the present invention, the heat-conducting wall includes a heat-conducting inner wall and a heat-conducting outer wall, a heat-conducting channel is provided between the heat-conducting inner wall and the heat-conducting outer wall, an axially extending heat-conducting sheet is provided in the heat-conducting channel, adjacent heat-conducting sheets are connected to form a triangular heat-conducting beam, the radial edges of the heat-conducting beam contact the heat-conducting inner wall and the heat-conducting outer wall respectively, multiple triangular heat-conducting beams are continuously distributed in the heat-conducting channel, and the included angle between adjacent heat-conducting sheets is selected from 30° to 170°.

[0010] Within the heat-conducting channel, heat-conducting sheets extend axially, and the angle between adjacent heat-conducting sheets is limited to the range of 30° to 170°. This allows the triangular heat-conducting beams formed by the connection of the heat-conducting sheets to constitute a directionally adjustable heat-conducting structure within the heat-conducting wall. When the angle between adjacent heat-conducting sheets is small, the triangular heat-conducting beams form continuous heat-conducting support in the axial direction, which helps to stably guide the heat generated inside the wound cell to the bottom of the cell. When the angle is large, the heat-conducting beams are more dispersed in the circumferential direction, enhancing the circumferential diffusion of heat within the heat-conducting wall and thus suppressing axial local heat concentration. By setting heat-conducting sheets within the aforementioned angle range, the heat-conducting wall achieves a synergistic effect between axial heat guidance and circumferential heat dispersion, thereby enabling adaptive redistribution of heat flow in the axial and circumferential directions under different operating conditions. Compared to using a single rib or a linear heat-conducting structure, this is more beneficial for improving the uniformity of the overall temperature field of the cell.

[0011] In one embodiment of the present invention, the heat-conducting wall includes a heat-conducting inner wall and a heat-conducting outer wall, a heat-conducting channel is provided between the heat-conducting inner wall and the heat-conducting outer wall, and an axially extending corrugated heat-conducting sheet is provided in the heat-conducting channel, the heat-conducting sheets being circumferentially connected.

[0012] Because the heat-conducting fins within the heat-conducting channel are a continuously distributed, circumferentially wave-shaped structure, they exhibit a periodic undulating shape while extending axially. When temperature changes cause thermal expansion and contraction of the inner and outer heat-conducting walls, the wave-shaped fins can absorb and buffer these dimensional changes through minute elastic deformations, thus preventing rigid tension or constraint between the inner and outer heat-conducting walls. Consequently, under repeated thermal cycling conditions, the stress concentration within the heat-conducting structure is reduced, the geometry of the heat-conducting channel remains relatively stable, and fluctuations in thermal conductivity caused by structural deformation are minimized, thereby improving the thermal stability and reliability of the heat-conducting wall during long-term operation.

[0013] In one embodiment of the present invention, the heat-conducting wall includes a heat-conducting inner wall and a heat-conducting outer wall, with a heat-conducting channel provided between the inner and outer walls. Axially extending heat-conducting sheets are arranged within the heat-conducting channel, and these sheets are arranged radially relative to the heat-conducting pillar. By arranging the heat-conducting sheets radially around the heat-conducting pillar within the heat-conducting channel, the heat conducted axially by the pillar can directly correspond to multiple heat-conducting sheets, thus structurally transforming the heat-conducting pillar from a single axial heat-conducting component into a node where heat is collected and distributed circumferentially. Through this radial arrangement, the heat generated in the central region of the wound cell, after being axially transferred through the heat-conducting pillar, can be instantly received by adjacent heat-conducting sheets and synchronously diffused radially and circumferentially, avoiding localized heat accumulation near the heat-conducting pillar due to gradual conduction through limited contact areas. This allows the axial heat-conducting path and the radial diffusion path to be connected and coordinated within the same structural level, reducing temperature concentration in the central region and improving the uniformity of heat distribution circumferentially within the cell.

[0014] In one embodiment of the present invention, the heat-conducting channel is filled with a phase-change refrigerant. When the heat-conducting channel is filled with the phase-change refrigerant, when heat is transferred from the inner heat-conducting wall, the outer heat-conducting wall, and the heat-conducting sheet into the heat-conducting channel, it no longer relies solely on the sensible heat conduction of the solid material, but is first absorbed by the phase-change refrigerant through a phase-change process. Because the phase-change refrigerant can absorb a large amount of heat in a near-constant temperature range within the phase-change temperature zone, the heat peak that appears on the heat-conducting wall in a short time is "retained" within the heat-conducting channel, which is beneficial for the uniform heat distribution of the battery cell winding itself.

[0015] In one embodiment of the present invention, a plurality of axially extending heat-conducting sheets are disposed inside the heat-conducting column, the two ends of the heat-conducting sheets being in contact with the bottom and / or top of the heat-uniform battery cell, and the central axis of the heat-conducting sheets coinciding with the central axis of the heat-conducting column.

[0016] By placing several axially extending heat-conducting plates inside the heat-conducting pillar, and ensuring that the axial ends of these plates contact the bottom and / or top of the thermally balanced battery cell, multiple parallel axial heat-conducting paths are formed inside the heat-conducting pillar. Heat, upon entering the pillar, is no longer transferred along a single path within the pillar itself, but rather simultaneously conducted axially via multiple heat-conducting plates, thereby reducing the overall axial thermal resistance of the heat-conducting pillar. Simultaneously, since the heat-conducting plates are directly disposed inside the pillar, the heat generated in the central region of the wound battery cell is dispersed within the pillar and transferred along the heat-conducting plates after entering. This prevents heat from concentrating and diffusing in the central region of the pillar before being conducted outwards, structurally weakening the temperature peak in the central region, reducing the likelihood of central hot spots, and improving the efficiency of heat dissipation from the central region to the battery cell ends.

[0017] In one embodiment of the present invention, the outer shell is selected from either cylindrical or rectangular.

[0018] In one embodiment of the present invention, the outer shell is cylindrical, the heat-conducting wall has a circular cross-section with radius r, the outer shell has radius R, and the height is H, where R, r, and H are all in mm, and 0.6 ≥ 2(R + r) / (R 2 -r 2 )+2 / H≥0.06.

[0019] This further limits the specific surface area and effective heat volume of the heat-conducting wall and the outer shell to a reasonable range, maximizing the heat exchange efficiency of the battery cell while ensuring the overall strength of the battery cell is maintained and the energy density loss is small.

[0020] In one embodiment of the present invention, the outer shell is a square column, and the cross-section of the heat-conducting wall is racetrack-shaped. The arc diameter of the heat-conducting wall on this cross-section is c, and its length is d. The length of the outer shell is a, its width is b, and its height is H, where a, b, c, d, and H are all in mm, and satisfy the following condition: 0.6 ≥ 4(2a + 2b + 2d + πc) / (4ab - πc). 2 -4cd)+2 / H≥0.06.

[0021] The heat-conducting wall has a racetrack-shaped cross-section. Compared to circular or rectangular heat exchange channels, this design avoids dead corners, has lower flow resistance, and allows for a higher degree of contact between the straight section and the cell winding, resulting in a larger heat exchange surface area. This design keeps the specific surface area and effective heat volume of the heat-conducting wall and the outer shell within a reasonable range. If this ratio is too small, the heat exchange capacity will be insufficient, reducing the beneficial effect of localized overheating of the cell. If this ratio is too large, it will increase the opening area of ​​the heat-conducting wall, occupying too much space in the cell winding and affecting the energy density and overall strength of the cell.

[0022] In one embodiment of the present invention, the outer shell is a square column, the heat-conducting wall has a circular cross-section with radius r, the side length of the outer shell is a, and the height is H, where r, a, and H are all in mm, and 0.6 ≥ 2(2a + πr) / (a 2 -πr 2 )+2 / H≥0.06.

[0023] This design ensures that the specific surface area and effective heat volume of the heat-conducting wall and the outer shell are within a reasonable range. If this ratio is too small, the heat exchange capacity will be insufficient, reducing the beneficial effect of localized overheating of the battery cell. If this ratio is too large, it will increase the cross-sectional area of ​​the heat-conducting wall, occupying too much space in the battery cell winding and affecting the energy density and overall strength of the battery cell. Furthermore, the circular cross-section of the heat-conducting wall has the smallest perimeter per unit area, which reduces the pressure of the cooling fluid, thereby reducing the flow resistance of the cooling fluid and improving the heat exchange efficiency. In addition, the circular cross-section of the heat-conducting wall has a radially symmetrical structure, which makes the distribution of cooling fluid more uniform.

[0024] In one embodiment of the present invention, the heat-conducting wall and the heat-conducting pillar are both insulated from the top, and the top is insulated from the outer shell; or, the heat-conducting pillar is in direct contact with the top, and a positive electrode and a negative electrode are provided on the top, and the positive electrode and the negative electrode are insulated from the top.

[0025] By configuring the connection relationships between the heat-conducting walls and pillars and the top with different optional structural forms, the thermal boundary conditions of the heat-conducting structure in the axial direction are configurable while keeping the main structure of the heat-conducting walls and pillars unchanged. When both the heat-conducting walls and pillars are insulated from the top, the heat-conducting structure forms a closed thermal boundary with the main body of the cell as the boundary, which is suitable for applications with high requirements for thermal stability and consistency. When the heat-conducting pillars are in direct contact with the top while the electrode posts are insulated from the top, the heat-conducting pillars provide a direct axial heat conduction path to the central area of ​​the cell, which is suitable for high-power conditions where the central heat generation is relatively concentrated. Thus, the same thermally balanced cell structure can achieve differentiated thermal management strategies through different top configurations without structural adjustments to the heat-conducting walls or pillars, improving the versatility and engineering adaptability of the solution under different application conditions. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0027] Figure 1This is a three-dimensional schematic diagram of a thermally balanced battery cell described in this invention;

[0028] Figure 2 This is a longitudinal cross-sectional schematic diagram of a thermally balanced battery cell described in this invention;

[0029] Figure 3 This is a schematic diagram of the transverse cross-section of a thermally balanced battery cell as described in this invention;

[0030] Figure 4 This is a longitudinal cross-sectional schematic diagram of another thermally balanced battery cell described in this invention.

[0031] Figure 5 This is a schematic diagram of the transverse cross-section of another thermally balanced battery cell described in this invention.

[0032] Figure 6 This is a longitudinal cross-sectional schematic diagram of another thermally balanced battery cell described in this invention.

[0033] Figure 7 This is a longitudinal cross-sectional schematic diagram of another thermally balanced battery cell described in this invention.

[0034] Figure 8 This is a three-dimensional schematic diagram of another thermally balanced battery cell described in this invention;

[0035] Figure 9 This is a longitudinal cross-sectional schematic diagram of another thermally balanced battery cell described in this invention.

[0036] Figure 10 This is a schematic diagram of the transverse cross-section of another thermally balanced battery cell described in this invention.

[0037] Among them, 1. outer shell, 2. wound cell, 21. first wound cell, 22. second wound cell, 3. heat-conducting wall, 4. heat-conducting pillar, 5. heat-conducting sheet. Implementation

[0038] Example 1

[0039] like Figures 1 to 3 As shown, this embodiment provides a thermally balanced battery cell, including a housing 1 and a wound battery cell 2. The wound battery cell 2 is disposed inside the housing 1. The wound battery cell 2 includes a first wound battery cell 21 and a second wound battery cell 22 arranged coaxially. The inner diameter of the first wound battery cell 21 is larger than the outer diameter of the second wound battery cell 22. A heat-conducting wall 3 is provided between the two. The heat-conducting wall 3 is a circumferentially connected annular closed structure that extends along the axial direction of the wound battery cell 2 and contacts the bottom of the thermally balanced battery cell, while being insulated from the top. The inner diameter of the heat-conducting wall 3 is 2% larger than the outer diameter of the second wound battery cell 22 and 2% smaller than the inner diameter of the first wound battery cell 21. This structure allows the heat-conducting wall 3 to be stably assembled between the two wound battery cells 2, while avoiding electrical connection with the top of the battery cell that would affect the insulation performance.

[0040] The first wound cell 21 has a heat-conducting column 4 coaxially arranged at its center. The two ends of the heat-conducting column 4 are in contact with the bottom and / or top of the heat-uniformed cell. Its outer diameter is 2% smaller than the inner diameter of the second wound cell 22. The heat-conducting column 4 can work with the heat-conducting wall 3 to form a two-way heat conduction path, further widening the heat conduction range inside the cell, effectively making up for the defect of long heat conduction path between the layers of the winding structure, and promoting heat exchange between the central area and the outer area of ​​the cell.

[0041] Furthermore, the top of the thermally balanced battery cell is the positive electrode, and the bottom is the negative electrode. The top is insulated from the battery cell body, and the heat-conducting pillar 4 is insulated from the top.

[0042] In this embodiment, the outer shell 1 is cylindrical, the heat-conducting wall 3 has a circular cross-section with a radius of r, the outer shell 1 has a radius of R and a height of H (R, r, and H are all in mm), and satisfies the relationship 2(R+r) / (R²-r²)+2 / H=0.1. This parameter design can accurately match the cell structure size and heat conduction requirements, ensure the structural compatibility between the heat-conducting wall 3 and the outer shell 1, and optimize the heat conduction efficiency, avoiding problems such as poor heat conduction or structural instability caused by size mismatch.

[0043] Example 2

[0044] like Figures 4 to 5 As shown, the difference from Embodiment 1 is that in this embodiment, the outer shell 1 is a square column, and the cross-section of the heat-conducting wall 3 is racetrack-shaped. The arc diameter of the heat-conducting wall 3 on this cross-section is c, the length is d, the length of the outer shell 1 is a, the width is b, and the height is H. a, b, c, d, and H are all in mm, and satisfy the following condition: 4(2a+2b+2d+πc) / (4ab-πc) 2 -4cd) + 2 / H = 0.1.

[0045] Furthermore, both the positive and negative terminals are insulated and positioned at the top of the battery cell, and the heat-conducting post 4 is in contact with both the top and bottom of the battery cell.

[0046] The heat-conducting wall 3 has a racetrack-shaped cross-section. Compared to circular or rectangular heat exchange channels, this design avoids dead corners, has lower flow resistance, and achieves a higher degree of contact between the straight section and the cell winding body, resulting in a larger heat exchange surface area. This design keeps the specific surface area and effective heat volume of the heat-conducting wall 3 and the outer shell 1 within a reasonable range. If this ratio is too small, the heat exchange capacity will be insufficient, reducing the beneficial effect of local overheating of the cell. If this ratio is too large, it will increase the opening area of ​​the heat-conducting wall 3, occupying too much space in the cell winding body and affecting the energy density and overall strength of the cell.

[0047] Example 3

[0048] like Figure 6As shown, the difference from Embodiment 1 is that in this embodiment, the outer shell 1 is a square column, the heat-conducting wall 3 has a circular cross-section with radius r, the side length of the outer shell 1 is a, and the height is H, and the units of r, a, and H are all mm. 2(2a+πr) / (a 2 -πr 2 ) + 2 / H = 0.06.

[0049] Furthermore, both the positive and negative terminals are insulated and positioned at the top of the battery cell, and the heat-conducting post 4 is in contact with both the top and bottom of the battery cell.

[0050] like Figure 7 As shown, in other embodiments, the top of the thermally balanced cell is the positive electrode and the bottom is the negative electrode. The top is insulated from the cell body, and the heat-conducting pillar 4 is insulated from the top.

[0051] Example 4

[0052] like Figures 8 to 10 As shown, the difference from Embodiment 1 is that in this embodiment, the heat-conducting wall 3 includes a heat-conducting inner wall and a heat-conducting outer wall. A heat-conducting channel is provided between the heat-conducting inner wall and the heat-conducting outer wall. A heat-conducting sheet 5 extending axially is provided in the heat-conducting channel. Adjacent heat-conducting sheets 5 are connected to form a triangular heat-conducting beam. The radial edges of the heat-conducting beam contact the heat-conducting inner wall and the heat-conducting outer wall respectively. Multiple triangular heat-conducting beams are continuously distributed in the heat-conducting channel. The included angle between adjacent heat-conducting sheets 5 is 125°.

[0053] Meanwhile, the positive and negative terminals of the battery cell are located at the top, and the positive and negative terminals are insulated from the top of the battery cell.

[0054] Within the heat conduction channel, heat conduction plates 5 extend axially, with adjacent heat conduction plates 5 forming an angle of 125°. This creates a triangular heat conduction beam formed by the connection of the heat conduction plates 5, constituting a directionally adjustable heat conduction structure within the heat conduction wall 3. This results in a more dispersed distribution of the heat conduction beams in the circumferential direction, enhancing the circumferential diffusion of heat within the heat conduction wall 3 and thus suppressing axial localized heat concentration.

[0055] Furthermore, in this embodiment, several axially extending heat-conducting plates 5 are disposed inside the heat-conducting pillar 4. The two ends of the heat-conducting plates 5 are in contact with the bottom and top of the thermally balanced battery cell, and the central axis of the heat-conducting plates 5 coincides with the central axis of the heat-conducting pillar 4. The heat-conducting channel is filled with a phase change refrigerant.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A thermally balanced battery cell, comprising a casing and a wound battery cell, characterized in that, The wound battery cell is disposed within the housing. The wound battery cell includes a first wound battery cell and a second wound battery cell arranged coaxially. The inner diameter of the first wound battery cell is larger than the outer diameter of the second wound battery cell. A heat-conducting wall is disposed between the first and second wound battery cells. The heat-conducting wall is a circumferentially connected annular closed structure. The heat-conducting wall extends axially along the wound battery cell and contacts the bottom of the heat-uniformed battery cell. The heat-conducting wall is insulated from the top of the heat-uniformed battery cell. The inner diameter of the heat-conducting wall is more than 1% larger than the outer diameter of the second wound battery cell, and the outer diameter of the heat-conducting wall is more than 1% smaller than the inner diameter of the first wound battery cell. A heat-conducting pillar is coaxially disposed at the center of the first wound battery cell. The two ends of the heat-conducting pillar contact the bottom and / or top of the heat-uniformed battery cell. The outer diameter of the heat-conducting pillar is more than 1% smaller than the inner diameter of the second wound battery cell.

2. The thermally balanced battery cell as described in claim 1, characterized in that, The heat-conducting wall includes a heat-conducting inner wall and a heat-conducting outer wall. A heat-conducting channel is provided between the heat-conducting inner wall and the heat-conducting outer wall. An axially extending heat-conducting plate is provided in the heat-conducting channel. Adjacent heat-conducting plates are connected to form a triangular heat-conducting beam. The radial edges of the heat-conducting beam contact the heat-conducting inner wall and the heat-conducting outer wall, respectively. Multiple triangular heat-conducting beams are continuously distributed in the heat-conducting channel. The included angle between adjacent heat-conducting plates is selected from 30° to 170°.

3. The thermally balanced battery cell as described in claim 1, characterized in that, The heat-conducting wall includes a heat-conducting inner wall and a heat-conducting outer wall. A heat-conducting channel is provided between the heat-conducting inner wall and the heat-conducting outer wall. An axially extending corrugated heat-conducting sheet is provided in the heat-conducting channel, and the heat-conducting sheets are circumferentially connected.

4. The thermally balanced battery cell as described in claim 1, characterized in that, The heat-conducting wall includes a heat-conducting inner wall and a heat-conducting outer wall. A heat-conducting channel is provided between the heat-conducting inner wall and the heat-conducting outer wall. An axially extending heat-conducting plate is provided in the heat-conducting channel. The heat-conducting plate is arranged radially relative to the heat-conducting column.

5. The thermally balanced battery cell as described in any one of claims 2-4, characterized in that, The heat conduction channel is filled with phase change refrigerant.

6. The thermally balanced battery cell as described in claim 1, characterized in that, The heat-conducting column is provided with several axially extending heat-conducting plates. The two ends of the heat-conducting plates are in contact with the bottom and / or top of the heat-uniform battery cell. The central axis of the heat-conducting plates coincides with the central axis of the heat-conducting column.

7. The thermally balanced battery cell as described in claim 1, characterized in that, The outer shell is selected from either cylindrical or rectangular.

8. The thermally balanced battery cell as described in claim 7, characterized in that, The outer shell is cylindrical, the heat-conducting wall has a circular cross-section with radius r, the outer shell has radius R, and the height is H, where R, r, and H are all in mm, and 0.6 ≥ 2(R + r) / (R 2 -r 2 )+2 / H≥0.

06.

9. The thermally balanced battery cell as described in claim 7, characterized in that, The outer shell is rectangular, and the heat-conducting wall has a racetrack-shaped cross-section. The diameter of the arc of the heat-conducting wall on this cross-section is c, and its length is d. The length of the outer shell is a, its width is b, and its height is H, where a, b, c, d, and H are all in mm. Furthermore, the following condition must be satisfied: 0.6 ≥ 4(2a + 2b + 2d + πc) / (4ab - πc). 2 -4cd)+2 / H≥0.

06.

10. The thermally balanced battery cell as described in claim 7, characterized in that, The outer shell is rectangular, the heat-conducting wall has a circular cross-section with radius r, the side length of the outer shell is a, and the height is H, where r, a, and H are all in mm. 0.6 ≥ 2(2a + πr) / (a 2 -πr 2 )+2 / H≥0.06.

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