Round-core square-shell lithium battery and battery module

Abstract

The utility model provides a kind of round core square shell lithium battery and battery module, it is related to battery technical field, round core square shell lithium battery includes square shell and roll core, roll core is cylindrical, it is set in square shell, the outer diameter of roll core and the diameter of incircle of square shell are adapted, roll core and the corner of square shell form the accommodation space for accommodating electrolyte.Through the composite structure design of "cylindrical roll core+square shell", two technical problems of traditional cylindrical battery are solved simultaneously.On the one hand, square shell improves the space utilization when battery is grouped, overcomes the defect that cylindrical battery module energy density is low;On the other hand, the accommodation space formed at corner increases electrolyte reserve, improves electrode wetting effect, improves the cycle life of battery.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a round-core square-shell lithium battery and battery module. Background Technology

[0002] Currently, lithium batteries, as important energy storage devices, are widely used in consumer electronics, electric vehicles, and energy storage systems. Among them, cylindrical batteries, which are encapsulated in a metal casing and have an internal wound electrode structure, have advantages such as mature manufacturing processes and good consistency, and are one of the mainstream battery types.

[0003] However, cylindrical batteries still have certain drawbacks in practical applications. Due to their extremely high internal space utilization, there is insufficient free electrolyte, which can easily affect battery performance during long-term cycling due to uneven electrolyte distribution, resulting in relatively poor cycle life. Existing technologies, such as the patent with publication number CN214957096U, disclose a cylindrical battery with secondary electrolyte replenishment, which solves the problem of insufficient electrolyte through secondary replenishment. However, this requires a completely new structural design for the cylindrical battery, resulting in a complex structure and a large overall volume, which not only increases manufacturing costs but also affects the flexibility of battery layout within a limited space. Furthermore, when cylindrical batteries are assembled into packs, the gaps between individual cells are relatively large, resulting in a lower overall energy density of the battery pack, making it difficult to meet the requirements of high-energy-density applications. Utility Model Content

[0004] In view of this, this utility model proposes a round-core square-shell lithium battery and battery module, which solves the problems of insufficient electrolyte and low energy density of traditional cylindrical battery structures.

[0005] The technical solution of this utility model is implemented as follows:

[0006] In a first aspect, this utility model provides a round-core, square-shell lithium battery, comprising:

[0007] Square shell;

[0008] The core, which is cylindrical, is housed within a square housing. The outer diameter of the core matches the inner diameter of the square housing, and the corners of the core and the square housing form a space for containing the electrolyte.

[0009] Based on the above technical solution, preferably, the core includes a cylindrical core body and an annular constraint member sleeved on the outer periphery of the core body, wherein the outer diameter of the annular constraint member is adapted to the inner circle diameter of the square shell.

[0010] Based on the above technical solution, preferably, the annular constraint member is centrally located along the axial direction of the core package body, and its height is greater than the electrode height of the core package body but less than the diaphragm height.

[0011] Based on the above technical solution, preferably, the annular constraint is made of metal.

[0012] Based on the above technical solution, preferably, the annular constraint member and the core body are in an interference fit.

[0013] Based on the above technical solution, preferably, it also includes a cover plate assembly. One end of the square housing is open. The cover plate assembly includes a top cover, a pole post, a first current collector, and an adapter plate. The pole post and the top cover are insulated and fixedly connected. The two ends of the adapter plate are electrically fixedly connected to the pole post and the first current collector, respectively. The first current collector is welded to the tab at one end of the core package body. The top cover and the open end of the square housing are sealed and fixedly connected.

[0014] Based on the above technical solution, preferably, the top cover is also provided with an explosion-proof valve and a liquid injection hole, the liquid injection hole is located at the corner of the top cover, and the first collection plate is provided with a guide hole.

[0015] Based on the above technical solution, preferably, a second current collector is provided at the end of the core package body away from the first current collector, one side of the second current collector is welded to the tab at that end of the core package body, and the other side of the second current collector is welded to the bottom surface of the square shell.

[0016] Secondly, this utility model provides a battery module comprising a plurality of round-core square-shell lithium batteries as described in the first aspect, wherein the plurality of round-core square-shell lithium batteries are arranged in an array and adjacent round-core square-shell lithium batteries are in contact with each other.

[0017] Based on the above technical solution, preferably, it also includes a liquid cooling plate, which is disposed between two adjacent rows or two adjacent columns of round-core square-shell lithium batteries, and the two large surfaces of the liquid cooling plate are respectively in contact with the square shells of the batteries on both sides.

[0018] The present invention has the following advantages over the prior art:

[0019] (1) By using a composite structure design of "cylindrical core + square shell", two major technical challenges of traditional cylindrical batteries are solved simultaneously. On the one hand, the square shell improves the space utilization rate when assembling batteries, overcoming the low energy density of cylindrical battery modules; on the other hand, the space formed at the corners increases the electrolyte storage capacity and improves the electrode wetting effect, thereby improving the cycle life of the battery. This design combines the process advantages of cylindrical batteries and the assembly advantages of square batteries without significantly increasing the complexity of the process, achieving a synergistic improvement in battery performance and energy density.

[0020] (2) A dual-protection structure was constructed by adding an annular constraint to the outer periphery of the core package. This design retains the electrochemical performance advantages of the cylindrical core while solving the electrode expansion problem through mechanical constraint. The precise dimensional matching between the constraint and the shell ensures efficient utilization of the battery's internal space while maintaining the electrolyte storage capacity. This innovative structure significantly improves the battery's cycle stability and safety performance without increasing process complexity.

[0021] (3) The annular constraint is centered along the axial direction of the core package body, which can ensure that the constraint force is evenly distributed in the effective working area of ​​the core package body and avoid local stress concentration caused by offset. The height of the annular constraint is greater than the height of the electrode of the core package body but less than the height of the diaphragm. With this setting, the extension of the diaphragm acts as a safety buffer. This height difference allows the diaphragm to form a protective extension at both ends of the constraint, which not only ensures the smooth transmission of electrolyte but also prevents the electrode from directly contacting the shell through the annular constraint.

[0022] (4) Achieving close arrangement through the geometric characteristics of the square shell. Array arrangement (such as rectangular or square matrix) makes full use of the planar contact advantage of the square shell, which significantly reduces the ineffective gaps between batteries compared with the honeycomb arrangement of traditional cylindrical batteries. As a result, the overall space utilization of the module can be improved, the energy density of the battery pack can be increased by 15%-20%, and the module structure design can be simplified.

[0023] (5) By seamlessly stacking and integrating the liquid cooling plate with the sidewall of the square cylindrical battery cell, the synergistic optimization of structural strength and heat dissipation performance is achieved. This design enables the liquid cooling plate and the battery cell to form a three-dimensional heat dissipation channel with full surface contact, which significantly improves the heat transfer efficiency. At the same time, it constructs a stable module frame with a honeycomb structure, which not only enhances the overall impact resistance but also maintains a compact spatial layout, effectively solving the heat dissipation challenges and mechanical strength requirements of high energy density battery modules during rapid charging and discharging. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a plan view of the assembly structure of the core and square shell disclosed in this utility model;

[0026] Figure 2 This is a three-dimensional structural diagram of the core disclosed in this utility model;

[0027] Figure 3 This is a schematic diagram of the internal structure of the round-core square-shell lithium battery disclosed in this utility model.

[0028] Figure 4 This is an exploded view of the cover plate assembly and the core disclosed in this utility model;

[0029] Figure 5 This is a three-dimensional structural diagram of the cover plate assembly disclosed in this utility model;

[0030] Figure 6 This is a schematic diagram of the overall structure of the round-core square-shell lithium battery disclosed in this utility model;

[0031] Figure 7 This is a three-dimensional structural diagram of the battery module disclosed in this utility model.

[0032] Figure 8 This is a three-dimensional structural diagram of a battery module with a liquid cooling plate disclosed in this utility model.

[0033] Figure label:

[0034] 1. Round core square shell lithium battery; 11. Square shell; 110. Accommodation space; 12. Core; 121. Core body; 122. Annular restraint; 13. Cover plate assembly; 131. Top cover; 132. Terminal post; 133. First current collector; 134. Adapter piece; 1311. Explosion-proof valve; 1312. Liquid injection hole; 1331. Flow guide hole; 14. Second current collector; 2. Liquid cooling plate. Detailed Implementation

[0035] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0036] like Figure 1 As shown, combined with Figure 2-6 This utility model discloses a round core square shell lithium battery 1, which includes a square shell 11 and a core 12.

[0037] The square casing 11, serving as the external encapsulation structure of the battery, adopts a regular cubic shape. The rigid metal shell provides physical protection and structural support for the internal components. Compared to a cylindrical casing, the planar structure of the square casing 11 is more conducive to the close arrangement of battery modules, reducing gaps between individual cells, improving space utilization during battery pack assembly, and significantly increasing the overall energy density of the battery pack.

[0038] The cylindrical core 12 is the core energy storage component of the battery, formed into a cylindrical structure by winding positive and negative electrode sheets and a separator. Its working principle is to maintain the winding method of traditional cylindrical batteries, inheriting the mature manufacturing process and good consistency of cylindrical batteries. The cylindrical structure allows the electrode materials to expand and contract uniformly during charging and discharging, avoiding the stress concentration problem at the corners of the square core 12.

[0039] The design, where the outer diameter of the core 12 matches the inscribed circle diameter of the square shell 11, ensures that the cylindrical core 12 can fill the internal space of the square shell 11 to the maximum extent. Precise dimensional matching ensures a stable contact between the outer surface of the core 12 and the inner wall of the shell. This design retains the structural advantages of the cylindrical core 12 while fully utilizing the internal space of the square shell 11. It optimizes space utilization and creates conditions for forming uniform accommodating spaces 110 at the corners.

[0040] The accommodating spaces 110 formed at the corners of the core 12 and the square casing 11, specifically, utilize the geometric differences between the cylinder and the square shape to create naturally formed gaps at the four corners as electrolyte storage areas. These spaces increase the capacity for free electrolyte, allowing the electrolyte to more evenly wet the electrode materials. This design significantly improves electrolyte distribution, alleviates the problem of insufficient electrolyte in traditional cylindrical batteries, and thus enhances the battery's cycle life and high-temperature performance.

[0041] The composite structure design of "cylindrical core 12 + square casing 11" simultaneously solves two major technical challenges of traditional cylindrical batteries. On the one hand, the square casing 11 improves the space utilization during battery assembly, overcoming the low energy density of cylindrical battery modules. On the other hand, the accommodating spaces 110 formed at the corners increase the electrolyte storage capacity and improve electrode wetting. This design combines the process advantages of cylindrical batteries and the assembly advantages of square batteries without significantly increasing process complexity, achieving a synergistic improvement in battery performance and energy density.

[0042] In this embodiment, refer to the appendix Figure 1 and 2 As shown, the core 12 includes a cylindrical core package body 121, which is made of positive and negative electrode sheets and a separator through a precision winding process. By maintaining the cylindrical structure, it is ensured that the electrode material can expand and contract uniformly during charging and discharging, thus avoiding stress concentration.

[0043] Since the core package body 121 is placed separately inside the square housing 11, the contact area between the core package body 121 and the square housing 11 is limited. During the charging and discharging process, the core package body 121 expands and contracts, which on the one hand causes the square housing 11 to bulge, and on the other hand causes the electrode sheets in the core package body 121 to loosen.

[0044] Therefore, the core 12 in this embodiment also includes an annular constraint member 122 sleeved on the outer periphery of the core package body 121. By applying radial constraint force to the core package body 121, the expansion and deformation of the electrode material during cycling is restricted, thereby preventing the square shell 11 from bulging. At the same time, the tight fit between the annular constraint member 122 and the core package body 121 can prevent the electrode from loosening or shifting, avoid performance degradation caused by expansion, and improve the structural stability and safety of the battery.

[0045] The outer diameter of the annular constraint 122 is matched with the inner circle diameter of the square housing 11. Through precise dimensional control, the annular constraint 122 can effectively fix the core pack body 121 and form an optimal fit with the square housing 11. This design ensures that the annular constraint 122 restricts the expansion of the core pack body 121 without affecting the internal spatial layout of the square housing 11. This optimizes the internal space utilization of the battery, ensuring structural strength while maintaining electrolyte storage space.

[0046] A dual-protection structure is constructed by adding an annular constraint 122 to the outer periphery of the core package body 121. This design retains the electrochemical performance advantages of the cylindrical core 12 while solving the electrode expansion problem through mechanical constraint. The precise dimensional matching between the constraint and the casing ensures efficient utilization of the battery's internal space while maintaining electrolyte storage capacity. This innovative structure significantly improves the battery's cycle stability and safety performance without increasing process complexity.

[0047] In some implementations, the annular constraint member 122 is centrally positioned along the axial direction of the core package body 121. This central positioning ensures that the constraint force is evenly distributed within the effective working area of ​​the core package body 121, avoiding localized stress concentration caused by offset. The height of the annular constraint member 122 is greater than the height of the electrode in the core package body 121 but less than the height of the separator. This arrangement allows the extended portion of the separator to act as a safety buffer. This height difference enables the separator to form a protective extension at both ends of the constraint member, ensuring smooth electrolyte transport while preventing the electrode from directly contacting the casing through the annular constraint member 122. This structural arrangement optimizes the internal spatial layout of the battery, balancing the dual requirements of structural constraint and electrolyte transport, thereby improving the battery's safety performance and lifespan.

[0048] It is worth noting that in this embodiment, the free electrolyte in the accommodating space 110 will flow at both ends in the axial direction of the core 12, thereby achieving the wetting of the electrode sheets in the core package body 121.

[0049] In some implementations, the annular constraint 122 is made of metal, which enhances the structural strength and durability of the constraint. The metal constraint effectively suppresses electrode expansion and improves the battery's thermal management performance, thereby enhancing the overall reliability and cycle life of the battery.

[0050] In this embodiment, the annular constraint 122 is a steel shell or an aluminum shell.

[0051] In some implementations, the annular constraint 122 and the core pack body 121 are interference-fitted. This interference fit design ensures a tight connection between the annular constraint 122 and the core pack body 121, effectively suppressing the expansion and deformation of the electrode material. This design improves the structural stability of the battery, ensures good contact at the electrode interface during long-term cycling, thereby optimizing battery performance and safety.

[0052] The round-core square-shell lithium battery 1 disclosed in this embodiment also includes a cover plate assembly 13, which serves as a battery sealing and electrical connection structure, as shown in the attached drawing. Figure 3-5 As shown, the cover plate assembly 13 includes a top cover 131, a pole post 132, a first collector plate 133, and an adapter plate 134.

[0053] The square shell 11 has an opening at one end, and the top cover 131 is sealed and fixedly connected to the opening end of the square shell 11. The connection can be achieved by welding to form an airtight and liquid-tight barrier.

[0054] The pole post 132 and the top cover 131 are insulated and fixedly connected to prevent short circuits between the pole post 132 and the metal top cover 131. The insulated and fixed connection between the pole post 132 and the top cover 131 is existing technology and will not be described in detail here.

[0055] The two ends of the adapter piece 134 are electrically fixedly connected to the terminal post 132 and the first current collector 133, respectively. The first current collector 133 is welded to the tab at one end of the core package body 121. The adapter piece 134 acts as a current transmission bridge, transmitting the current generated by the reaction of the core package body 121 through the tab to the first current collector 133, then through the adapter piece 134 to the terminal post 132, and finally to the external circuit. The adapter piece can be bent when the cover plate assembly 13 is inserted into the housing.

[0056] In this embodiment, the tabs on the end face of the core package body 121 are full tabs, which are welded to the first collector plate 133 using a flattening process.

[0057] In this embodiment, the top cover 131 is also provided with an explosion-proof valve 1311 and a liquid injection hole 1312. The liquid injection hole 1312 is located at the corner of the top cover 131, and the first collection plate 133 is provided with a guide hole 1331.

[0058] The explosion-proof valve 1311 is used to release pressure by rupturing through a pre-designed weak area when the internal pressure of the battery rises abnormally (such as thermal runaway or overcharging), which is existing technology. The electrolyte injection hole 1312 is located at the corner of the top cover 131, optimizing the electrolyte injection path and using the corner space as an injection channel. The corner position design avoids interference with components such as the terminal post 132 and the explosion-proof valve 1311, improving injection efficiency, ensuring that the electrolyte fully wets the core pack body 121, and reducing air bubble residue, thereby improving battery consistency and cycle performance.

[0059] The first collector plate 133 is provided with a guide hole 1331 to provide a flow channel for the electrolyte and promote the uniform distribution of the electrolyte inside the core body 121.

[0060] In some implementations, a second current collector 14 is provided at the end of the core pack body 121 away from the first current collector 133, forming a bipolar current collection structure to achieve efficient current transmission from the core pack body 121 to the battery casing. One side of the second current collector 14 is welded to the tab at that end of the core pack body 121, and the other side of the second current collector 14 is welded to the bottom surface of the square casing 11. This constitutes a low-impedance path, optimizes the current distribution path, reduces internal resistance, and enhances the battery's heat dissipation capacity, making it particularly suitable for high-rate charge and discharge scenarios.

[0061] The second current collector 14 is welded to the bottom surface of the square casing 11, using the casing as a conductive component to form a stable current output path. This design eliminates the need for an additional terminal post 132 structure, simplifies the internal layout of the battery, reduces production costs, and improves the battery's thermal management performance through the high thermal conductivity of the metal casing.

[0062] This utility model embodiment also discloses a battery module, as shown in the attached drawing. Figure 7 As shown, it includes multiple round-core square-shell lithium batteries 1, which are arranged in an array and adjacent round-core square-shell lithium batteries 1 are in contact with each other.

[0063] The square housing 11 enables a close arrangement. The array-like arrangement (such as a rectangular or square matrix) fully utilizes the planar contact advantage of the square housing 11, significantly reducing ineffective gaps between cells compared to the honeycomb arrangement of traditional cylindrical batteries. This improves the overall space utilization of the module, increasing the battery pack energy density by 15%-20%, while simplifying the module's structural design.

[0064] It is worth noting that an insulating layer is provided between the round core and square shell lithium battery 1 to avoid short circuits between the square shells 11.

[0065] As some implementation methods, refer to the appendix. Figure 8As shown, the battery module also includes a liquid cooling plate 2, which is disposed between two adjacent rows or two adjacent columns of round-core square-shell lithium batteries 1. The two large surfaces of the liquid cooling plate 2 are respectively in contact with the square shells 11 of the batteries on both sides.

[0066] By seamlessly stacking and integrating the liquid cooling plate 2 with the sidewall of the square cylindrical battery cell, a synergistic optimization of structural strength and heat dissipation performance is achieved. This design creates a three-dimensional heat dissipation channel with full surface contact between the liquid cooling plate 2 and the battery cell, significantly improving heat transfer efficiency. Simultaneously, it constructs a stable module frame with a honeycomb-like structure, enhancing overall impact resistance while maintaining a compact spatial layout. This innovative structure effectively addresses the heat dissipation challenges and mechanical strength requirements of high-energy-density battery modules during rapid charging and discharging, providing an optimized solution for power battery systems that combines high rigidity, efficient heat dissipation, and high integration.

[0067] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A round-core, square-shell lithium battery, characterized in that, include: Square shell (11); The core (12) is cylindrical and is disposed inside the square shell (11). The outer diameter of the core (12) is matched with the inner circle diameter of the square shell (11). The core (12) and the corner of the square shell (11) form a accommodating space (110) for containing electrolyte.

2. The round-core square-shell lithium battery as described in claim 1, characterized in that: The core (12) includes a cylindrical core body (121) and an annular constraint member (122) sleeved on the outer periphery of the core body (121). The outer diameter of the annular constraint member (122) is adapted to the inner circle diameter of the square shell (11).

3. The round-core square-shell lithium battery as described in claim 2, characterized in that: The annular constraint member (122) is centrally located along the axial direction of the core package body (121), and its height is greater than the electrode height of the core package body (121) but less than the diaphragm height.

4. The round-core square-shell lithium battery as described in claim 2, characterized in that: The annular constraint (122) is made of metal.

5. The round-core square-shell lithium battery as described in claim 2, characterized in that: The annular constraint member (122) and the core body (121) are interference fit.

6. The round-core square-shell lithium battery as described in claim 2, characterized in that: It also includes a cover plate assembly (13), one end of the square housing (11) is open, the cover plate assembly (13) includes a top cover (131), a pole post (132), a first current collector (133) and an adapter plate (134), the pole post (132) and the top cover (131) are insulated and fixedly connected, the two ends of the adapter plate (134) are electrically fixedly connected to the pole post (132) and the first current collector (133) respectively, the first current collector (133) is welded to the tab at one end of the core package body (121), and the top cover (131) and the open end of the square housing (11) are sealed and fixedly connected.

7. The round-core, square-shell lithium battery as described in claim 6, characterized in that: The top cover (131) is also provided with an explosion-proof valve (1311) and a liquid injection hole (1312). The liquid injection hole (1312) is located at the corner of the top cover (131), and a guide hole (1331) is provided on the first collection plate (133).

8. The round-core square-shell lithium battery as described in claim 6, characterized in that: The core package body (121) is provided with a second current collector (14) at one end away from the first current collector (133). One side of the second current collector (14) is welded to the tab at that end of the core package body (121), and the other side of the second current collector (14) is welded to the bottom surface of the square shell (11).

9. A battery module comprising a plurality of round-core prismatic-shell lithium batteries (1) as described in any one of claims 1 to 8, characterized in that: Multiple round-core square-shell lithium batteries (1) are arranged in an array, with adjacent round-core square-shell lithium batteries (1) in contact with each other.

10. The battery module as described in claim 9, characterized in that: It also includes a liquid cooling plate (2), which is disposed between two adjacent rows or two adjacent columns of round core square shell lithium batteries (1), and the two large surfaces of the liquid cooling plate (2) are respectively in contact with the square shells (11) of the batteries on both sides.

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