A multi-cell battery module based on negative poisson's ratio structure

Abstract

The application discloses a multi-cell battery module based on a negative Poisson's ratio structure, which comprises a battery shell (10), a plurality of battery monomers stacked in the battery shell (10), and an electric connection structure (4) arranged between adjacent battery monomers, and each battery monomer is sleeved with a negative Poisson's ratio mechanical metamaterial supporting unit (3); the negative Poisson's ratio mechanical metamaterial supporting unit (3) is formed by a plurality of negative Poisson's ratio mechanical metamaterial cells (32) connected in sequence in the circumferential direction. The multi-cell battery module based on the negative Poisson's ratio structure has high impact resistance.

Description

Technical Field

[0001] This invention relates to the field of micro battery technology, specifically to a multi-cell battery module based on a negative Poisson's ratio structure with strong impact resistance. Background Technology

[0002] When micro battery modules are used in aerospace, special equipment, high overload electronic equipment, and micro electronic systems operating in shock environments, they need to achieve high voltage output within a limited space while withstanding large transient shock loads.

[0003] To improve the overall impact resistance of micro batteries under high overload impact environments, Chinese invention patent application (application number: 202610509377.2, application date: April 17, 2026) proposes a micro lithium-ion battery, including a negative electrode shell at one end and a positive electrode shell at the opposite end. At least one battery sub-cell is disposed between the negative and positive electrode shells. The battery also includes an impact-resistant support ring of the same height as the sub-cell. The impact-resistant support ring is fitted outside the battery sub-cell and placed within the cavity formed by the negative and positive electrode shells. The number of battery sub-cells is 2 to 4, stacked and connected in series. This battery employs an impact-resistant battery structure with a ring-shaped constrained bending beam mechanical metamaterial support structure. By setting a ring-shaped constrained bending beam support ring around the battery cell, the bending beam undergoes dominant bending deformation under axial impact load, converting part of the impact energy into structural deformation energy. This reduces the direct transmission of impact load to the internal components of the battery and improves the voltage output stability of the battery during impact.

[0004] However, as the number of battery cells increases from two to four, five, six, seven, or eight cells, the axial stacking height of the battery module increases, and its impact response characteristics change. During high overload impacts, the inertial response of each battery cell and the relative motion between layers become more pronounced, resulting in cumulative displacement between multiple battery cells. This disturbs the electrode sheets, foam metal, current collectors, and the conductive interfaces between adjacent battery cells. For the aforementioned multi-layer stacked structure, relying solely on the impact energy dissipation effect of the bending beam is insufficient to adequately limit the lateral deformation of the battery cells and the relative displacement between layers.

[0005] Therefore, the problem with the existing technology is that the interlayer relative displacement and overall stability of multi-cell battery modules are insufficient when multiple cells are stacked, resulting in insufficient impact resistance. Summary of the Invention

[0006] The purpose of this invention is to address the problems of insufficient interlayer relative displacement and overall stability in existing ring-constrained bending beam mechanical metamaterial impact-resistant battery structures under multi-cell stacking conditions, and to provide a multi-cell battery module based on a negative Poisson's ratio structure with strong impact resistance.

[0007] The technical solution to achieve the purpose of this invention is as follows: A multi-cell battery module based on a negative Poisson's ratio structure includes a battery housing, multiple battery cells stacked within the battery housing, and an electrical connection structure disposed between adjacent battery cells. Each battery cell is externally fitted with a negative Poisson's ratio mechanical metamaterial support unit.

[0008] Preferably, the negative Poisson's ratio mechanical metamaterial support unit is formed by connecting multiple negative Poisson's ratio mechanical metamaterial cells sequentially along the circumference.

[0009] Compared with the prior art, the significant advantages of this invention are: 1. Improved Impact Resistance: This invention addresses the issue of increased interlayer relative displacement in existing ring-constrained bending beam mechanical metamaterial impact-resistant structures under multi-unit stacking conditions. The mechanical metamaterial cells are further designed with a negative Poisson's ratio effect. Under axial impact loads, the negative Poisson's ratio mechanical metamaterial not only absorbs and dissipates impact energy through bending and rotation of the beam, but also generates radial inward contraction deformation, thus forming radial constraints on the internal battery cells and achieving better impact resistance. This structure is particularly suitable for multi-layer stacked batteries with four or more cells, effectively reducing the relative displacement between individual cells during impact and improving overall structural stability. In a five-cell stacked battery example, under a 20,000 g impact load, the battery using the negative Poisson's ratio mechanical metamaterial support structure of this invention exhibits a transient voltage drop controlled within 58 mV. Compared to a battery using a ring-constrained bending beam mechanical metamaterial support structure, the transient voltage fluctuation amplitude is further reduced by approximately 34.83% under the same impact conditions, indicating that the negative Poisson's ratio structure has superior impact response control capability under multi-unit stacking conditions.

[0010] 2. Effectively reduces interlayer relative displacement in multi-cell batteries: Compared to mechanical metamaterial structures that primarily rely on the bending deformation of curved beams for impact energy dissipation, this invention further utilizes the geometric deformation characteristics of negative Poisson's ratio cells. When the supporting structure is subjected to axial impact, the cells contract radially inward, thereby forming lateral constraints on the internal battery cells and reducing lateral displacement and interlayer misalignment of multi-cell batteries during impact. Therefore, this invention is particularly suitable for axially stacked battery modules with four, five, or more cells.

[0011] 3. Designable mechanical properties: The structure and geometric parameters of the mechanical metamaterial unit can be designed according to the target mechanical properties, and the mechanical response of the battery module can be controlled through curved beam bending, cell rotation, negative Poisson's ratio deformation or other structural deformation mechanisms.

[0012] 4. Facilitates modular stacking: Using a mechanical metamaterial unit and its internal electrochemical components as a basic battery unit, the number of basic battery units can be increased or decreased according to actual output voltage and capacity requirements to achieve modular battery module construction. The open circuit voltage of the 7-layer single cell is 21.56V. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall external structure of a multi-cell battery module based on a negative Poisson's ratio structure according to the present invention.

[0014] Figure 2 for Figure 1 The diagram shows the exploded structure of the battery module.

[0015] Figure 3 for Figure 1 The diagram shows a cross-sectional view of the battery module.

[0016] Figure 4 for Figure 2 A schematic diagram of the exploded structure of a single battery cell.

[0017] Figure 5 for Figure 4 A schematic diagram of a medium-negative Poisson's ratio mechanical metamaterial support unit.

[0018] Figure 6 for Figure 5 A schematic diagram of the cell structure of a medium-negative Poisson's ratio mechanical metamaterial.

[0019] In the diagram: 10 Battery casing, 11 Positive electrode casing, 12 Negative electrode casing, 21 First battery cell, 211 First electrode sheet, 212 First separator, 213 First negative electrode metal sheet, 214 First foam metal, 215 First current collector, 22 Second battery cell, 23 Third battery cell, 24 Fourth battery cell, 25 Fifth battery cell, 3 Negative Poisson's ratio mechanical metamaterial support unit, 31 Negative Poisson's ratio mechanical metamaterial internal cavity, 32 Negative Poisson's ratio mechanical metamaterial cell, 321 First support part, 322 Second support part, 323 Annular connecting rib, 324 Inclined beam structure, 3241 First inclined beam, 3242 Second inclined beam, 4 Electrical connection structure, 41 Conductive adhesive layer. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] It should be understood that the described embodiments are used to illustrate the technical concept of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the concept of the present invention, those skilled in the art can adjust the geometry, structural dimensions, number of battery cells, electrochemical system, and electrical connection method of the negative Poisson's ratio mechanical metamaterial cell according to actual application needs, and all such adjustments should fall within the technical scope of the present invention.

[0022] like Figures 1-3 As shown, the present invention is a multi-cell battery module based on a negative Poisson's ratio structure, which includes a battery housing 10, multiple battery cells stacked within the battery housing 10, multiple negative Poisson's ratio mechanical metamaterial support units 3 fitted on the outside of each battery cell, and an electrical connection structure 4 disposed between adjacent battery cells.

[0023] The battery casing 10 includes a positive electrode shell 11 and a negative electrode shell 12 that are interlocked. The positive electrode shell 11 and the negative electrode shell 12 together form an internal space for accommodating multiple battery cells and a negative Poisson's ratio mechanical metamaterial support unit 3. Multiple battery cells are stacked sequentially along the axial direction of the battery casing 1, and electrical connections between adjacent battery cells are achieved through an electrical connection structure 4.

[0024] In this embodiment, the battery module includes a first battery cell 21, a second battery cell 22, a third battery cell 23, a fourth battery cell 24, and a fifth battery cell 25 stacked sequentially along the axial direction. Adjacent battery cells are connected in series via an electrical connection structure 4. The other end of the first battery cell 21 is electrically connected to the positive electrode shell 11, and the other end of the fifth battery cell 25 is electrically connected to the negative electrode shell 12, thereby achieving a higher overall output voltage.

[0025] The number of battery cells is not limited to five in this embodiment. It can be set to two, three, four, five, or more, depending on the target output voltage, battery module size, and actual application requirements. As the number of battery cells increases, the stacking height of the battery module along the axial direction increases. Under axial impact loads, the relative motion of each battery cell due to inertia becomes more pronounced, thus placing higher demands on the overall stability and interlayer constraint capability of the supporting structure.

[0026] like Figure 4 As shown, the internal structure of the battery cell is explained using the first battery cell 21 as an example.

[0027] The first battery cell 21 includes a first electrode sheet 211, a first separator 212, a first negative electrode metal sheet 213, a first foam metal 214, and a first current collector 215.

[0028] The first electrode sheet 211, the first separator 212, the first negative electrode metal sheet 213, the first foam metal 214, and the first current collector 215 are arranged sequentially along the axial direction of the battery cell. The first electrode sheet 211 is used to provide an electrochemical reaction interface and can be a fluorinated carbon electrode, a manganese dioxide electrode, a carbon-based electrode, or other positive electrode materials, depending on the actual battery system. The first negative electrode metal sheet 213 can be made of lithium metal or lithium alloy. The first foam metal 214 can be made of nickel foam and is used to provide electrode support and improve current transmission. The first current collector 215 is used to collect current and make electrical connections between adjacent battery cells.

[0029] Each battery cell has the same structure. The second battery cell 22, the third battery cell 23, the fourth battery cell 24, and the fifth battery cell 25 may adopt the same or corresponding layered structure as the first battery cell 21.

[0030] The main improvement of this invention is that negative Poisson's ratio mechanical metamaterial support units 3 are respectively set on the outer periphery of each battery cell, so as to utilize the radial inward contraction characteristics of the negative Poisson's ratio structure during axial compression to control the impact load and constrain the displacement of the multi-cell stacked battery module.

[0031] like Figure 5 As shown, the negative Poisson's ratio mechanical metamaterial support unit 3 has a ring structure, with its central region forming a negative Poisson's ratio mechanical metamaterial internal chamber 31. The negative Poisson's ratio mechanical metamaterial internal chamber 31 is used to accommodate the corresponding battery cell.

[0032] The negative Poisson's ratio mechanical metamaterial support unit 3 is sleeved on the outer periphery of the corresponding battery cell and located in the internal accommodating space formed by the positive electrode shell 11 and the negative electrode shell 12.

[0033] There is a tiny gap between the inner side of the negative Poisson's ratio mechanical metamaterial support unit 3 and the outer periphery of the battery cell. The size of this gap is such that the battery cell is not affected by the deformation of the negative Poisson's ratio mechanical metamaterial support unit 3 under force, and at the same time, it is constrained by the inner cavity 31 formed by the sequential connection of multiple negative Poisson's ratio mechanical metamaterial cells 32 in the circumferential direction, so that it does not shake.

[0034] The negative Poisson's ratio mechanical metamaterial support unit 3 is set separately from the corresponding battery cell. The support unit 3 mainly bears and regulates external impact loads through its own structural deformation, without needing to form an integral structure with the battery module.

[0035] The internal chamber 31 of the negative Poisson's ratio mechanical metamaterial support unit 3 is designed according to the external dimensions of the corresponding battery cell to ensure that the battery cell can be installed in the internal chamber 31; the external dimensions of the support unit 3 are designed according to the internal space of the battery housing 10 so that multiple support units 3 can be assembled with the corresponding battery cells inside the battery housing 10.

[0036] like Figure 6 As shown, each negative Poisson's ratio mechanical metamaterial support unit 3 is formed by connecting multiple negative Poisson's ratio mechanical metamaterial cells 32 sequentially along the circumference.

[0037] The negative Poisson's ratio mechanical metamaterial cell 32 includes a first support portion 321 and a second support portion 322 arranged in parallel with each other, and also includes an inclined beam structure 324 with one end fixedly connected to the first support portion 321 and the other end fixedly connected to the second support portion 322.

[0038] The inclined beam structure 324 includes a first inclined beam 3241 and a second inclined beam 3242 arranged symmetrically on an axis. One end of the first inclined beam 3241 is fixedly connected to one end of the first bearing part 321, and the other end of the first inclined beam 3241 is fixedly connected to one end of the second bearing part 322. One end of the second inclined beam 3242 is fixedly connected to the other end of the first bearing part 321, and the other end of the second inclined beam 3242 is fixedly connected to the other end of the second bearing part 322.

[0039] As a preferred option, The first inclined beam 3241 and the second inclined beam 3242 are bent plate-like structures, and their creases are parallel to the first bearing part 321.

[0040] As a preferred option, The folds of the first inclined beam 3241 and the second inclined beam 3242 are close to each other.

[0041] Multiple mechanical metamaterial cells 32 are arranged circumferentially along the negative Poisson's ratio mechanical metamaterial support unit 3 and are interconnected by annular connecting ribs 323, thereby forming a closed annular mechanical metamaterial support structure.

[0042] The first bearing part 321 and the second bearing part 322 are used to bear and transmit external loads in the axial direction, and the inclined beam structure is used to bend and rotate under axial compressive load.

[0043] When the negative Poisson's ratio mechanical metamaterial support unit 3 is subjected to an axial impact load, the first bearing part 321 and the second bearing part 322 move closer together, driving the inclined beam inside the cell 32 to bend and rotate. Since the cell 32 adopts a negative Poisson's ratio configuration, the negative Poisson's ratio mechanical metamaterial support unit 3 undergoes radial inward contraction while being axially compressed.

[0044] The radial inward contraction direction is toward the internal cavity 31 of the negative Poisson's ratio mechanical metamaterial, thus enabling radial constraint on the battery cells located in the internal cavity 31 while the supporting structure undergoes axial compression deformation.

[0045] During the impact load process, the inclined beam 323 first generates controlled deformation through bending and rotation, converting part of the impact energy into the deformation energy of the mechanical structure, thereby reducing the peak value of the transient load directly transmitted to the battery cell and prolonging the impact load action time.

[0046] At the same time, the radial inward contraction generated by the negative Poisson's ratio cell 32 restricts the lateral displacement of the battery cell during the impact process, so that the support unit 3 has both the functions of impact energy dissipation and battery cell displacement constraint.

[0047] For battery modules consisting of two or a few battery cells, a single-layer support structure can provide a certain impact buffering capacity. However, for multi-cell battery modules formed by stacking four or more battery cells along the axial direction, the relative displacement between different layers of battery cells becomes more pronounced during impact as the stacking height increases. In this case, the radial inward contraction generated by the negative Poisson's ratio mechanical metamaterial support unit 3 can constrain each layer of battery cells, thereby reducing the relative movement between multiple layers of battery cells and improving the overall structural stability of the battery module.

[0048] The annular connecting rib 323 is used to connect multiple circumferentially arranged mechanical metamaterial cells 32, so that each cell can participate in bearing the load together and coordinate the deformation between adjacent cells, thereby reducing the possibility of excessive deformation and local instability of local cells.

[0049] Material selection for negative Poisson's ratio mechanical metamaterials: In this embodiment, the negative Poisson's ratio mechanical metamaterial support unit 3 is made of thermoplastic polyurethane elastomer (TPU) material and is fabricated using micro-nano 3D printing technology.

[0050] Compared to the aforementioned ring-shaped constrained bending beam mechanical metamaterial support structure made of high-temperature resistant resin, TPU material exhibits better flexibility and deformation capacity. When the negative Poisson's ratio cell structure is subjected to axial impact load, TPU material allows the inclined beams within the cell to undergo more complete bending and rotational deformation, thereby achieving a greater effective deformation stroke.

[0051] Therefore, the use of TPU material in this embodiment is not a simple material replacement, but rather a combination with a negative Poisson's ratio cell configuration, which allows the support unit to more fully utilize the deformation characteristics of the negative Poisson's ratio structure, forming a more obvious axial buffer and radial inward contraction during the impact process.

[0052] In multi-cell stacked battery modules, this flexible material can adapt to large impact deformations while avoiding the direct transfer of large transient loads to individual battery cells due to excessive rigidity of the support structure, thereby improving the impact buffering capacity of the support structure.

[0053] Design of structural parameters for negative Poisson's ratio mechanical metamaterials: To obtain a negative Poisson's ratio mechanical metamaterial support unit 3 suitable for multi-cell battery modules, this embodiment parametrically designs the negative Poisson's ratio mechanical metamaterial cell 32 based on the size of the battery cell 21, the internal space of the battery casing 10, the target impact resistance, and the TPU micro-nano 3D printing requirements, and uses Abaqus finite element parameter scanning to determine the preferred structural parameters.

[0054] Step 1: Parametric Design. Based on the battery module dimensions and the internal space of the battery casing 10, the overall dimensions of the negative Poisson's ratio mechanical metamaterial support unit 3 are determined. In this embodiment, the support unit 3 has an outer diameter of 18.5 mm, an inner diameter of 16.5 mm, and an axial height of 1.25 mm. Based on this, the cell beam length L, the inclined beam length Ls, the inclined beam inclination angle θ, and the beam thickness t are used as the main design parameters.

[0055] Step 2: Finite Element Parameter Scanning. A model of a TPU negative Poisson's ratio mechanical metamaterial support element 3 was established using Abaqus finite element software. While maintaining consistency in material, boundary conditions, and loading conditions, the parameters were scanned in combination. Specifically, the scanning range for the cell beam length L was 0.8–1.2 mm, and the scanning range for the inclined beam length L... s The beam thickness is 0.5–0.9 mm, the inclination angle θ is 60°–80°, and the beam thickness t is 0.10–0.20 mm. Finite element analysis was used to compare the axial load response, axial deformation, radial contraction of the internal chamber 31, and impact energy absorption characteristics of support unit 3 under different parameter combinations.

[0056] Step 3: Comprehensive screening and determination of optimal parameters. Based on the finite element parameter scanning results, and combined with the battery module installation space, structural load-bearing capacity, radial constraint capacity, and TPU micro-nano 3D printing manufacturing requirements, different parameter combinations were comprehensively screened. The optimal parameters for this embodiment were ultimately determined as follows: cell beam length L = 1.0 mm, inclined beam length L... s =0.6 mm, inclined beam angle θ=70°, beam thickness t=0.15 mm.

[0057] The above parameter combination enables the negative Poisson's ratio mechanical metamaterial support unit 3 to undergo controlled deformation during axial impact, accompanied by radial inward contraction of the internal cavity 31, thereby taking into account both impact energy dissipation and radial constraint of the internal battery cells, and is suitable for the impact-resistant structural design of multi-cell battery modules.

[0058] Impact response of TPU negative Poisson's ratio mechanical metamaterial Under axial impact load, the TPU negative Poisson's ratio mechanical metamaterial support unit 3 first undergoes overall compression deformation, and the inclined beam in cell 32 undergoes bending and rotation.

[0059] Because TPU material has good deformation capacity, the inclined beam can generate sufficient structural deformation under impact load, so that the impact energy is dissipated inside the supporting structure and the impact load is reduced from being directly transmitted to the battery cells.

[0060] As the degree of axial compression increases, the negative Poisson's ratio cell 32 undergoes radial inward contraction, which reduces the circumferential dimension of the support unit 3 and causes it to contract towards the internal cavity 31.

[0061] This structural response enables the support unit 3 to form a radial constraint on the internal battery cells when subjected to axial impact, thus limiting the lateral displacement of the battery cells.

[0062] When multiple battery cells are stacked along the axial direction, a corresponding negative Poisson's ratio mechanical metamaterial support unit 3 is set around the periphery of each layer of battery cells. Each layer of support unit constrains the corresponding battery cell, thereby reducing the interlayer relative displacement when the entire stacked battery module is subjected to impact.

[0063] Therefore, the negative Poisson's ratio mechanical metamaterial support unit 3 in this embodiment has both impact energy dissipation function and multi-layer battery cell displacement constraint function, and is particularly suitable for high overload impact protection of multi-cell stacked battery modules.

[0064] Electrical connection between battery cells like Figure 3 As shown, an electrical connection structure 4 is provided between adjacent battery cells. The electrical connection structure 4 includes a conductive adhesive layer 41 and a corresponding current collector structure.

[0065] A conductive adhesive layer 41 is disposed at the electrical connection interface of adjacent battery cells to achieve conductive connection between adjacent battery cells. The conductive adhesive layer 41 can be made of a suitable conductive carbon-based adhesive material depending on the battery system.

[0066] In this embodiment, the conductive adhesive layer 41 is used to connect the current collector and electrode assembly between adjacent battery cells, so that multiple battery cells form a stable series electrical connection along the axial direction.

[0067] It should be noted that the conductive adhesive layer 41 is a conventional connection structure used in battery modules to achieve interlayer conductive connection. Its main function is to form a stable current transmission path, and it is not the main improvement of the impact-resistant mechanical structure of this invention.

[0068] Battery module assembly In this embodiment, TPU negative Poisson's ratio mechanical metamaterial support unit 3 is first prepared according to the design dimensions, and the printed support unit is then cleaned, post-processed, and its dimensions are measured.

[0069] Subsequently, multiple battery cells were prepared and each battery cell was placed in the internal cavity 31 of the corresponding negative Poisson's ratio mechanical metamaterial support unit 3.

[0070] After the assembly of the single-layer battery cell and support unit 3 is completed, multiple battery cells are stacked sequentially along the axial direction, and an electrical connection structure 4 is set between adjacent battery cells.

[0071] After stacking and electrical connection are completed, the overall structure is installed into the battery housing 10, so that the positive electrode housing 11 and the negative electrode housing 12 are located at the two ends of the battery module, and the housing is snapped in and encapsulated.

[0072] After assembly, multiple negative Poisson's ratio mechanical metamaterial support units 3 are located on the outer periphery of the corresponding battery cell, and each support unit 3 forms a support system corresponding to the multilayer battery cell in the axial direction.

[0073] Electrical performance and impact resistance of this embodiment In this embodiment, five battery cells are connected in series along the axial direction to form a battery module. Test results show that the open-circuit voltage of the five-cell battery module reaches 15.56 V.

[0074] In the high overload impact test, an axial impact load was applied to the battery module. Under an impact load of 20,000 g, the transient voltage drop of the battery module using TPU negative Poisson's ratio mechanical metamaterial support unit 3 was controlled within 58 mV.

[0075] Compared with battery modules using a ring-constrained bending beam mechanical metamaterial support structure, the transient voltage fluctuation amplitude of this embodiment is further reduced by approximately 34.83% under the same impact conditions.

[0076] The above results show that the TPU negative Poisson's ratio mechanical metamaterial support unit 3 used in this embodiment can dissipate impact energy through cell bending and rotation when the multi-cell stacked battery module is subjected to high overload impact. At the same time, the radial inward contraction generated by the negative Poisson's ratio structure restricts the relative displacement of the battery cells, thereby improving the overall impact resistance of the multi-cell battery module and the electrical connection stability during the impact process.

[0077] This invention does not change the separate arrangement between the mechanical metamaterial support structure and the battery assembly. Instead, it changes the cell configuration of the mechanical metamaterial based on the original ring-shaped constrained bending beam structure, so that the support ring, which mainly relies on bending deformation to absorb impact energy, further has the characteristic of lateral inward contraction during axial compression.

[0078] When subjected to axial compressive loads, the negative Poisson's ratio mechanical metamaterial structure not only dissipates impact energy through the bending and rotation of its cell beams, but also exhibits lateral inward contraction deformation, unlike conventional materials. Therefore, when multiple battery cells are stacked axially and subjected to impact loads, the mechanical metamaterial support unit can simultaneously achieve axial impact load control and radial displacement constraint, thereby reducing the relative displacement between adjacent battery cells and improving the overall stability of the multi-cell battery module.

[0079] Especially for multi-layer stacked battery modules composed of four or more battery cells, this invention utilizes the radial contraction characteristics of negative Poisson's ratio mechanical metamaterials during axial compression to constrain the lateral displacement of the battery cells, thereby reducing the relative movement between battery cells in each layer during impact and reducing the degree of transient mechanical disturbance to the interlayer electrical connection structure, thus improving the structural integrity and voltage output stability of multi-cell battery modules under high overload impact conditions.

[0080] In summary, this invention, based on the existing ring-constrained bending beam mechanical metamaterial impact-resistant battery structure, addresses the issues of increased interlayer relative displacement and reduced overall stability in multi-cell stacking by improving the cell configuration of the mechanical metamaterial and using TPU material with good deformability to fabricate negative Poisson's ratio mechanical metamaterial support units. The cell structure parameters are determined using Abaqus finite element parameter scanning, enabling the support units to not only dissipate impact energy through structural deformation during axial impact but also to utilize the negative Poisson's ratio effect to generate radial inward contraction, constraining the internal battery cells. This improves the structural stability and voltage output stability of the multi-cell stacked battery module under high overload impact conditions.

Claims

1. A multi-cell battery module based on a negative Poisson's ratio structure, comprising a battery housing (10), a plurality of battery cells stacked within the battery housing (10), and an electrical connection structure (4) disposed between adjacent battery cells, characterized in that: Each of the battery cells is fitted with a negative Poisson's ratio mechanical metamaterial support unit (3).

2. The multi-cell battery module according to claim 1, characterized in that: The negative Poisson's ratio mechanical metamaterial support unit (3) is formed by connecting multiple negative Poisson's ratio mechanical metamaterial cells (32) sequentially along the circumference.

3. The multi-cell battery module according to claim 2, characterized in that: There is a tiny gap between the inner side of the negative Poisson's ratio mechanical metamaterial support unit (3) and the outer periphery of the battery cell. The size of this gap is such that the battery cell is not affected by the deformation of the negative Poisson's ratio mechanical metamaterial support unit (3) under force, and is constrained by the inner cavity (31) formed by the sequential connection of multiple negative Poisson's ratio mechanical metamaterial cells (32) in the circumferential direction, so that it does not shake.

4. The multi-cell battery module according to claim 3, characterized in that: The negative Poisson's ratio mechanical metamaterial cell (32) includes a first support part (321) and a second support part (322) arranged in parallel with each other, and also includes a sloping beam structure (324) with one end fixedly connected to the first support part (321) and the other end fixedly connected to the second support part (322).

5. The multi-cell battery module according to claim 4, characterized in that: The inclined beam structure (324) includes a first inclined beam (3241) and a second inclined beam (3242) arranged in an axisymmetric manner. One end of the first inclined beam (3241) is fixedly connected to one end of the first bearing part (321), and the other end of the first inclined beam (3241) is fixedly connected to one end of the second bearing part (322); One end of the second inclined beam (3242) is fixedly connected to the other end of the first bearing part (321), and the other end of the second inclined beam (3242) is fixedly connected to the other end of the second bearing part (322).

6. The multi-cell battery module according to claim 5, characterized in that: The first inclined beam (3241) and the second inclined beam (3242) are bent plate-like structures with their creases parallel to the first bearing part (321).

7. The multi-cell battery module according to claim 6, characterized in that: The creases of the first inclined beam (3241) and the second inclined beam (3242) are close to each other.

8. The multi-cell battery module according to any one of claims 1 to 7, characterized in that: The number of battery cells shall not be less than two.

9. The multi-cell battery module according to any one of claims 1 to 7, characterized in that: The negative Poisson's ratio mechanical metamaterial support unit (3) is made of thermoplastic polyurethane elastomer (TPU) material.

10. The multi-cell battery module according to claim 9, characterized in that: The negative Poisson's ratio mechanical metamaterial support unit (3) is formed by micro-nano 3D printing.

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