Thermally balanced prismatic cells

Abstract

The utility model provides a kind of hot equalization square shell electric core, including shell, cover and bare electric core, the positive, negative pole lug of bare electric core is connected with the positive, negative pole post of cover, the maximum surface area of bare electric core stack setting makes the face parallel to each other, heat conduction plate is set between the adjacent bare electric core, the heat conduction plate is sheet structure, first heat conduction channel and second heat conduction channel are set in the heat conduction plate, the first heat conduction channel both ends opening, the second heat conduction channel both ends are closed, the first heat conduction channel and second heat conduction channel are all along the height direction of square shell electric core extension, the width of heat conduction plate is less than the width of aluminum shell, can significantly reduce the thermal resistance of bare electric core chip interlayer, improve the temperature distribution in electric core, reduce the temperature difference of center and edge, upper and lower end, form fast heat conduction and heat release composite effect, to realize more uniform heat field.

Description

Technical Field

[0001] This utility model relates to a square-shell battery cell, and more particularly to a square-shell battery cell that can achieve thermal equilibrium during operation. Background Technology

[0002] With the expanding application scenarios of lithium-ion power batteries, the demand for their energy density and power density is also increasing. To balance high capacity and high heat dissipation performance, stacked or wound prismatic cells are widely used due to their dense electrode arrangement, short internal current path, and high volume utilization. In existing technologies, multiple bare cells are typically stacked and packaged in a prismatic casing, with the positive and negative electrodes led out through a cover plate structure. However, as the number of bare cells in a single prismatic casing increases and the operating current rises, the thermal coupling effect between the bare cells becomes more pronounced. Uneven heat dissipation can lead to excessively high local temperatures, resulting in accelerated capacity decay, reduced cycle life, and even safety risks.

[0003] To improve thermal management performance, some existing technologies incorporate metal heat-conducting plates or liquid cooling plates on the exterior of the prismatic battery casing to enhance overall thermal conductivity. However, externally mounted heat-conducting plates offer only a single heat conduction path, making it difficult to simultaneously manage the lateral and vertical heat flow of the bare cells within the casing. Furthermore, they cannot adapt heat dissipation to different heat-generating areas within the bare cells. Therefore, designing heat-conducting components that combine high thermal efficiency with a compact structure for prismatic battery cells with multiple bare cells remains a key technical challenge in the field of prismatic battery cell thermal management. Utility Model Content

[0004] This utility model addresses at least one of the problems of existing square-shell battery cells by providing a thermally balanced square-shell battery cell, comprising a shell, a cover plate, and bare cells. The positive and negative tabs of the bare cells are connected to the positive and negative terminals of the cover plate. The bare cells are stacked cells, and the number is at least two. The bare cells are stacked such that the surfaces with the largest surface area are parallel to each other. A heat-conducting plate is disposed between adjacent bare cells. The heat-conducting plate has a sheet-like structure and contains a first heat-conducting channel and a second heat-conducting channel. The first heat-conducting channel is open at both ends, and the second heat-conducting channel is closed at both ends. Both the first and second heat-conducting channels extend along the height direction of the square-shell battery cell. The width of the heat-conducting plate is smaller than the width of the shell, and the shell can be made of aluminum as the base material.

[0005] The first thermal conduction channel forms a continuous heat conduction path along the height of the prismatic cell, enabling rapid transfer of localized heat to the cover plate or bottom. The partially enclosed cavity of the second thermal conduction channel acts as a thermal buffer and peak clipping mechanism during charging, discharging, or fast charging. In terms of thermal management, this solution utilizes a heat-conducting plate with both the first and second thermal conduction channels, significantly reducing the thermal resistance between bare cell layers and improving the internal temperature distribution of the cell. This reduces the temperature difference between the center and edges, and between the top and bottom, creating a combined effect of rapid heat conduction and release, resulting in a more uniform thermal field. A uniform thermal field helps improve reaction consistency, reduces localized polarization and lithium deposition, thereby extending cycle life and improving capacity retention.

[0006] Meanwhile, the heat-conducting plate, acting as an interlayer skeleton, can evenly distribute the expansion and contraction stress of the bare cells, reducing the risk of casing bulging and localized stress concentration. The width of the heat-conducting plate is smaller than the width of the aluminum shell, with a buffer gap at the edge. This not only prevents heat from being directly transferred to the shell sidewalls and causing localized overheating, but also preserves channels for electrolyte wetting and gas escape, improving assembly and formation consistency.

[0007] Preferably, a phase change material is disposed inside the second heat conduction channel, and an axially extending strip-shaped heat dissipation protrusion is disposed inside the second heat conduction channel. An inclined heat dissipation fin extending radially is disposed on the strip-shaped heat dissipation protrusion, and through holes are uniformly distributed on the heat dissipation fin.

[0008] The strip-shaped heat dissipation ridges inside the heat-conducting plate extend along the height of the battery cell, forming a continuous high thermal conductivity skeleton. This not only expands the heat conduction path and effective heat transfer area, but also forms a longitudinal heat conduction link between layers. In addition, the inclined heat dissipation fins cause airflow disturbance in the channel, continuously disrupting the thermal boundary layer, thereby improving the convective heat transfer coefficient and enhancing heat dissipation efficiency.

[0009] Meanwhile, when phase change materials are used alone in a closed channel, their internal thermal conductivity is low, which can easily lead to local melting and thermal hysteresis. The uniform distribution of through holes on the heat dissipation fins allows the phase change material to begin melting and undergoing phase change when the prismatic cell releases heat. Some gas or low-viscosity liquid phases can generate natural convection within the through holes, thereby introducing an auxiliary convection heat transfer mechanism into the closed phase change cavity and further improving the overall heat dissipation capacity.

[0010] Preferably, the outer surface of the heat-conducting plate includes a ceramic dielectric coating.

[0011] Ceramic dielectric coatings have good breakdown resistance and thermal conductivity, which can effectively isolate the potential difference between the heat-conducting plate and the adjacent bare cell electrode or metal shell, prevent short circuits, creepage or electrochemical corrosion caused by the conductivity of the heat-conducting plate, thereby improving the insulation safety level of the cell system and maintaining good thermal diffusion capability, avoiding the increase in thermal resistance caused by traditional organic insulating paint or coatings.

[0012] Preferably, the heat-conducting plate includes a ceramic dielectric coating area and a blank area. The ceramic dielectric coating area is disposed on the outer and upper surfaces of the heat-conducting plate near the tab, and the blank area is disposed on the outer surface of the heat-conducting plate away from the tab.

[0013] The tab area is typically the region with the highest current density and fastest temperature rise within the battery cell, and it is also the area most prone to electric field concentration and electrochemical corrosion. Placing the ceramic dielectric coating area on the outer and upper surfaces of the heat-conducting plate near the tab effectively isolates the high-potential region at the tab, preventing leakage or short circuit risks caused by metal conduction in the heat-conducting plate. The blank area minimizes interfacial thermal resistance and enhances heat dissipation, achieving a balance between insulation, leakage prevention, and heat dissipation performance in the heat-conducting plate.

[0014] Preferably, the heat-conducting plate includes a protective area, which is a region less than 2 cm from the tab and with a width of 2 to 4 cm. The ratio of the thickness of the ceramic dielectric coating area of ​​the protective area to the thickness of the ceramic dielectric coating area of ​​other areas is selected from 2:1 to 4:1.

[0015] The protective zone is defined as an area less than 2 cm from the tab and 2–4 cm wide, precisely covering the part of the cell with the highest potential and most concentrated heat load. By designing the ceramic dielectric coating thickness of the protective zone to be 2–4 times that of other areas, its dielectric strength and insulation withstand voltage can be significantly improved. The thick coating in the protective zone and the thin coating in the non-protected zone form a thermal gradient, allowing heat to smoothly transition from the tab area to the surrounding heat dissipation area along the heat-conducting plate, achieving directional heat conduction and slow temperature difference release.

[0016] Preferably, the heat-conducting plate has a first heat-conducting channel and / or a second heat-conducting channel at both ends near the tabs, and a solid structure near the center of the heat-conducting plate, with the solid structure spaced apart from the first or second heat-conducting channel.

[0017] The tab area of ​​a battery cell is typically where current is most concentrated and heat generation is most significant. Placing heat conduction channels close to the tabs can significantly shorten the heat transfer path from the heat source to the heat conduction channels, allowing localized heat to be conducted more quickly, thereby effectively reducing the temperature rise of the tabs and the busbar area. The central part of the heat conduction plate is designed as a solid structure, which can establish a stable heat transfer path between the heat conduction channels, ensuring overall temperature uniformity.

[0018] Preferably, copper foam is disposed within the heat conduction channel, and the copper foam is distributed along the strip-shaped heat dissipation protrusions and heat dissipation fins.

[0019] Copper foam has a high thermal conductivity and a high specific surface area. Its porous network structure can significantly increase the effective heat conduction path density inside the heat conduction channel without significantly increasing the weight. Combined with strip-shaped heat dissipation ridges and heat dissipation fins, it further enhances the convective heat transfer inside the channel, ultimately strengthening the overall heat uniformity distribution and heat dissipation capacity of the prismatic battery cell. Attached Figure Description

[0020] Figure 1 This is a three-dimensional schematic diagram of a thermally balanced square-shell battery cell disclosed in this utility model;

[0021] Figure 2 This is a perspective schematic diagram of a thermally balanced square-shell battery cell disclosed in this utility model.

[0022] Figure 3 This is a schematic diagram of the structure of a heat-conducting plate disclosed in this utility model;

[0023] Figure 4 This is a partial cross-sectional view of another heat-conducting plate disclosed in this utility model;

[0024] Figure 5 This is a schematic diagram of another heat-conducting plate disclosed in this utility model;

[0025] Figure 6 This is a schematic diagram of another heat-conducting plate disclosed in this utility model;

[0026] Among them, 1. shell, 2. cover plate, 3. bare cell assembly, 31. bare cell, 4. heat conduction plate, 41. first heat conduction channel, 42. second heat conduction channel, 43. strip heat dissipation protrusion, 44. heat dissipation fin, 45. ceramic dielectric coating, 46. solid structure. Detailed Implementation

[0027] 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.

[0028] Example 1

[0029] like Figures 1-3As shown, this embodiment provides a prismatic battery cell with uniform heat generation, including a housing 1, a cover plate 2, and a bare cell assembly 31 disposed inside the housing 1. The bare cell assembly 31 includes two bare cells 31, which can be stacked or wound. Each bare cell 31 includes a positive electrode, a negative electrode, and a separator, with the positive and negative electrodes extending to form positive and negative tabs, respectively. The two bare cells 31 are stacked parallel to each other, with their surfaces having the largest surface areas corresponding to each other, and a heat-conducting plate 4 is disposed between them. The positive and negative tabs of the bare cells 31 are electrically connected to the positive and negative terminals on the cover plate 2, respectively. The cover plate 2 and the housing 1 are sealed together to form a closed cavity for the prismatic battery cell.

[0030] A heat-conducting plate 4 is positioned between two bare battery cells 31 to achieve heat conduction and temperature equalization during battery cell operation. The heat-conducting plate 4 has a sheet-like structure and is made of a high thermal conductivity metal (such as aluminum, copper, or their alloys) to ensure high in-plane thermal conductivity. The heat-conducting plate 4 contains two independent heat-conducting channels: a first heat-conducting channel 41 and a second heat-conducting channel 42. The first heat-conducting channel 41 extends along the height of the battery cell, with open ends, allowing direct connection to the heat dissipation cavity of the cover plate 2 or the bottom heat dissipation structure. The second heat-conducting channel 42 is a closed structure, sealed at both ends, and not connected to the outside. The first heat-conducting channel 41 and the second heat-conducting channel 42 are arranged laterally, both extending along the thickness centerline of the battery cell, thus forming a heat-conducting and heat-equalizing composite structure within the heat-conducting plate 4.

[0031] In operation, the first heat conduction channel 41 forms a continuous heat conduction path along the height of the cell, quickly transferring localized heat generated inside the bare cell 31 to the cover plate 2 or the bottom, thereby improving longitudinal heat dissipation efficiency. The closed cavity formed by the first heat conduction channel 41 and the second heat conduction channel 42 acts as a thermal buffer and peak-shaving mechanism under high heat load conditions such as charging, discharging, and fast charging, effectively balancing the temperature rise rate and temperature distribution. The heat conduction plate 4 not only conducts heat but also serves as an interlayer skeleton structure, evenly distributing the expansion and contraction stress of the bare cell 31 during cycling, reducing the risk of bulging of the casing 1 and localized stress concentration. The buffer gaps at the edges prevent direct heat conduction to the sidewalls of the casing 1, avoiding localized overheating, and provide channels for sufficient electrolyte wetting and gas escape, thereby improving the assembly consistency and formation stability of the cell, achieving a uniform heating, stable structure, and efficient heat dissipation.

[0032] Example 2

[0033] like Figure 4As shown, the difference between this embodiment and Embodiment 1 is that the second heat conduction channel 42 is filled with a phase change material to regulate temperature fluctuations during cell operation by absorbing and releasing latent heat; a strip-shaped heat dissipation ridge 43 extending along the height of the cell is provided inside the second heat conduction channel, and radially extending inclined heat dissipation fins 44 are arranged on the ridge, with through holes evenly distributed on the surface of the heat dissipation fins 44 (not shown in the attached figure). This composite structure plays a role in heat absorption buffering and rapid heat conduction within a limited space.

[0034] The strip-shaped heat dissipation ridges 43 inside the heat-conducting plate 4 run through the height direction, forming a continuous high thermal conductivity path. This allows the heat generated during the operation of the battery cell to be quickly transferred from the local high-temperature area to the entire heat-conducting plate 4. Furthermore, the inclined heat dissipation fins 44 on the ridges further improve the convective heat transfer efficiency. The inclined arrangement allows the cooling medium to flow within the channel, creating a highly efficient heat exchange zone within the channel, thereby significantly improving heat dissipation capacity and temperature uniformity.

[0035] Example 3

[0036] like Figure 5 As shown, the difference between this embodiment and Embodiment 1 is that the outer surface of the heat-conducting plate 4 includes a ceramic dielectric coating 45. The ceramic dielectric coating 45 has excellent breakdown resistance and high thermal conductivity, which can effectively isolate the potential difference between the heat-conducting plate 4 and the adjacent bare battery cell 31 electrode or metal shell 1, preventing short circuits, creepage, or electrochemical corrosion caused by the conductivity of the heat-conducting plate 4. At the same time, the thermal conductivity of the ceramic dielectric coating 45 is far superior to that of traditional organic insulating varnish or resin coating, which can alleviate heat accumulation and local overheating.

[0037] In this embodiment, the surface of the heat-conducting plate 4 adopts a regional design, specifically including a ceramic dielectric coating area 45 and a blank area. The ceramic dielectric coating area 45 is located on the outer and upper surfaces of the heat-conducting plate 4 near the electrode, while the blank area is located on the outer surface of the heat-conducting plate 4 away from the electrode. The electrode area is the part with the highest current density inside the battery cell, and this area also has a high risk of electrochemical corrosion. By setting the ceramic dielectric coating area 45 near the electrode, the risk of leakage, creepage, or breakdown caused by metal conduction in the heat-conducting plate 4 can be effectively prevented, thereby ensuring the safe operation of the battery cell under high voltage and high temperature environments.

[0038] Example 4

[0039] The difference between this embodiment and embodiment 3 is that the heat-conducting plate 4 includes a protective area (not shown in the figure). The protective area is a region that is less than 2 cm away from the tab and has a width of 2 to 4 cm. The ratio of the thickness of the ceramic dielectric coating 45 in the protective area to the thickness of the ceramic dielectric coating 45 in other areas is selected from 2:1 to 4:1.

[0040] The protected area is defined as a region less than 2 cm from the tab and 2–4 cm wide, precisely covering the part of the cell with the highest potential and most concentrated heat load. By designing the thickness of the ceramic dielectric coating 45 in the protected area to be 2–4 times that of other areas, its dielectric strength and insulation withstand voltage can be significantly improved. The thick coating in the protected area and the thin coating in the non-protected area form a thermal gradient, allowing heat to smoothly transition from the tab position to the surrounding heat dissipation area along the heat-conducting plate 4, achieving directional heat conduction and slow release of temperature difference.

[0041] Example 5

[0042] like Figure 6 As shown, the difference between this embodiment and Embodiment 1 is that a first heat conduction channel and a second heat conduction channel are provided at both ends of the heat conduction plate 4 near the tabs, and a solid structure 46 is provided near the center of the heat conduction plate 4. The solid structure 46 is spaced apart from the first or second heat conduction channel. Furthermore, copper foam (not shown in the attached figure) is provided in the heat conduction channel, and the copper foam is distributed along the strip-shaped heat dissipation protrusions 43 and the heat dissipation fins 44.

[0043] The heat conduction channels are arranged near the electrode tabs, which can significantly shorten the heat transfer path from the heat source to the heat conduction channels, allowing local heat to be conducted more quickly, thereby effectively reducing the temperature rise of the electrode tabs and the junction area. Furthermore, the solid structure 46 can establish stable heat transfer between each heat conduction channel. The copper foam combined with the strip heat dissipation protrusions 43 and heat dissipation fins 44 further enhances the convective heat transfer within the channels.

[0044] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the initial concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A thermally balanced square-shell battery cell, comprising a shell, a cover plate, and a bare battery cell, wherein the positive and negative tabs of the bare battery cell are connected to the positive and negative terminals of the cover plate, characterized in that, The bare cells are stacked cells, and the number is at least two. The bare cells are stacked such that the surfaces with the largest surface area are parallel to each other. A heat-conducting plate is provided between adjacent bare cells. The heat-conducting plate is a sheet structure. A first heat-conducting channel and a second heat-conducting channel are provided in the heat-conducting plate. The first heat-conducting channel is open at both ends, and the second heat-conducting channel is closed at both ends. Both the first heat-conducting channel and the second heat-conducting channel extend along the height direction of the square-shell cell. The width of the heat-conducting plate is smaller than the width of the shell.

2. The thermally balanced prismatic battery cell according to claim 1, characterized in that, The second heat conduction channel is provided with a phase change material, and an axially extending strip-shaped heat dissipation ridge is provided inside the second heat conduction channel. The strip-shaped heat dissipation ridge is provided with radially extending inclined heat dissipation fins, and the heat dissipation fins are uniformly distributed with through holes.

3. The thermally balanced prismatic battery cell according to claim 1, characterized in that, The outer surface of the heat-conducting plate includes a ceramic dielectric coating.

4. The thermally balanced prismatic battery cell according to claim 3, characterized in that, The heat-conducting plate includes a ceramic dielectric coating area and a blank area. The ceramic dielectric coating area is disposed on the outer and upper surfaces of the heat-conducting plate near the electrode, and the blank area is disposed on the outer surface of the heat-conducting plate away from the electrode.

5. The thermally balanced prismatic battery cell according to claim 3 or 4, characterized in that, The heat-conducting plate includes a protective area, which is a region less than 2 cm from the tab and with a width of 2 to 4 cm. The ratio of the thickness of the ceramic dielectric coating area of ​​the protective area to the thickness of the ceramic dielectric coating area of ​​other areas is selected from 2:1 to 4:

1.

6. The thermally balanced prismatic battery cell according to claim 1 or 2, characterized in that, The heat-conducting plate has a first heat-conducting channel and / or a second heat-conducting channel at both ends near the tabs, and a solid structure near the center of the heat-conducting plate. The solid structure is spaced apart from the first heat-conducting channel or the second heat-conducting channel.

7. The thermally balanced prismatic battery cell according to claim 6, characterized in that, Copper foam is disposed in the first and second heat conduction channels, and the copper foam is distributed along the strip-shaped heat dissipation protrusions and heat dissipation fins.

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