Consumable elastic splint and metal lithium battery module

Abstract

The present invention relates to a consumable elastic splint and a lithium metal battery module. The consumable elastic splint comprises an outer elastic splint, a middle foam consumable layer, and an inner rigid splint, which are bonded together in sequence. The module comprises a battery array, a binding wire, and the consumable elastic splint. A consumable elastic splint is provided at each end of the battery array, and the binding wire is wound around the battery array and consumable elastic splint assembly, so that the two consumable elastic splints clamp the battery array in the direction of expansion. The present invention solves the problem of significant thickness shrinkage and deformation of lithium metal secondary batteries during use, as well as the problems of excessive pressure causing the battery array diaphragm to rupture, splint delamination and fracture, irreversible expansion of the battery module, pressure mismatch, and deformation, fire, and explosion of the battery body. This ensures the stability and reliability of the module's external dimensions and the high cycle life and safety of the module.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a consumable elastic splint and a metal lithium battery module. Background Art

[0002] As lithium metal secondary battery technology matures, it can now achieve charge and discharge cycles within a certain range, with specific energies exceeding 530 Wh / kg, making it extremely valuable for applications in high-energy-density applications. However, compared to traditional graphite anode materials, lithium metal secondary batteries lack the space for lithium ion insertion, resulting in significant volume expansion during charging. This is particularly true for prismatic, flexible-package lithium metal batteries, where the thickness expansion can typically exceed 8%. This expansion can cause significant deformation of the module's structural components, generating significant external compressive forces and potentially damaging the electrical equipment. Using rubber cushioning significantly increases the weight of the battery module, negating the advantage of high specific energy. Without compressive control of the thickness of lithium metal secondary batteries, the negative electrode lithium metal material within the battery will pulverize within just a few weeks, deactivating a significant amount of the negative electrode active material and turning into dead lithium, making it unable to participate in charge and discharge, leading to rapid capacity decay. Lithium metal secondary batteries require a certain amount of pressure to compress and undergo significant dimensional changes, making lightweight lithium metal secondary battery module design difficult, and existing methods cannot achieve a low structural weight. In addition, when the surface of the metal lithium secondary battery electrode is rigidly connected, the negative electrode metal lithium will be severely deformed, resulting in an increase in internal current density and, in turn, an increase in internal resistance.

[0003] CN108054315A "Square lithium-ion battery pack for space use" and CN205810901U "Soft-pack power battery module" both use a pull rod tensioning method to reduce weight. The structure adopted cannot meet the high specific energy requirements of metal lithium secondary batteries. CN208646202U "A sandwich structure composite material battery box" uses a foam sandwich core to reduce the weight of the box, improve thermal insulation performance and impact resistance, but does not involve the application of foam elasticity. CN113991233A "A temperature-controlled composite splint for high-expansion lithium-ion battery pack" uses a structure in which a splint, a heat-conducting plate, a rigid foam board, a heating belt and a leveling plate are bonded in sequence. The splint is combined with the original text. Figure 2 The splint is hollow in shape, and does not involve elastic properties, multiple layers, or bonding areas, nor does it involve the feature that the width of the middle foam consumption layer is smaller than the width of the outer elastic splint. Summary of the Invention

[0004] The purpose of the present invention is to provide a consumable elastic splint and a metal lithium battery module to solve the technical problems of mismatched pressure applied to the volume expansion and contraction process of the metal lithium secondary battery during the charge and discharge cycle, excessive deformation amplitude that cannot be matched, and internal short circuit caused by deformation of the single cell due to clamping of the ordinary splint, which may cause fire and explosion.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a consumable elastic splint, comprising an outer elastic splint, a middle foam consumable layer and an inner rigid splint bonded in sequence, wherein the width of the middle foam consumable layer is smaller than that of the outer elastic splint.

[0006] The above-mentioned consumable elastic splint, wherein the material of the inner rigid splint is selected from one of carbon fiber, aluminum alloy, and magnesium alloy. The inner rigid splint can provide a flat extrusion plane for the end of the internal single battery to prevent the deformation of the splint from causing the deformation of the single battery, which causes the internal ear of the single battery to be repeatedly bent and rubbed, etc., resulting in failure of the diaphragm inside the end single battery and short circuit; the material of the middle foam consumable layer is selected from high-density foam material, especially high-density PMI material, and the density is selected from 0.1g / cm3 to 0.3g / cm3. At this time, the elastic modulus of the material is between 100Mpa and 300Mpa. The PMI material in this density range has a large compression modulus and can be compressed under high pressure. The middle foam consumable layer can be In order to achieve a lightweight support structure, on the other hand, it can provide additional space for the irreversible expansion of single cells during the charging and discharging process of metal lithium batteries, and at the same time, it can limit the maximum value of the clamping force of the splint within the designed range to achieve pressure protection for the single cells, and prevent the single cells from causing internal short circuits due to excessive pressure; the width of the middle foam consumption layer is smaller than the width of the outer elastic splint, and a suspended space is directly constructed between the outer elastic splint and the inner rigid plate, providing a reciprocating deformation space for the outer elastic splint, and preventing the inner rigid plate from being squeezed and deformed by the outer elastic splint; the material of the outer elastic splint is carbon fiber, and the outer elastic splint is a multi-layer structure, which can solve the problem of insufficient tension of a single-layer thin outer elastic splint or breakage of a single-layer thick outer elastic splint due to excessive deformation.

[0007] The above-mentioned consumable elastic splint, in which the outer elastic splint of the multi-layer structure has only the center position between each layer as the bonding and fixing area, and the remaining area is in a free state, in contact and allowed to slide, and the bonding and fixing area accounts for 10% to 50% of the total surface area, which can solve the problem that the middle part of the multi-layer elastic splint is prone to outward arching when it is not bonded or the elastic splint is prone to breakage due to bonding on both sides; between the outer elastic splint and the middle foam consumable layer, and between the middle foam consumable layer and the inner rigid splint, only the center position is the bonding and fixing area, and the remaining area is in a free state, in contact and allowed to slide, and the bonding and fixing area accounts for 10% to 50% of the total surface area, which can solve the problem that the foam consumable layer is pulled during the recovery process of the outer elastic splint, resulting in damage to the foam consumable layer.

[0008] The above-mentioned consumable elastic splint, wherein the number of layers and the thickness of a single layer are adjusted to change the maximum deformation amplitude of the outer elastic splint and the magnitude of the elastic force generated by the deformation.

[0009] The working process of the consumable elastic splint matches the charging and discharging process of the metal lithium battery module. The consumable elastic splint is installed in the discharged state of the metal lithium battery module and provides a certain initial pressure; after the metal lithium battery module is fully charged, the outer elastic splint of the consumable elastic splint bends, and after the outer elastic splint bends, the two sides of the foam consumable layer are compressed and deformed; the metal lithium battery module is then discharged to the discharged state, and the two sides of the foam consumable layer remain in the compressed and deformed state without recovering; in the subsequent cycle process, the foam consumable layer basically maintains its previous state. As the number of cycles of the metal lithium battery module increases, the irreversible expansion of the metal lithium battery becomes more and more obvious, and the consumable elastic splint is gradually compressed as a whole to offset the irreversible expansion volume of the metal lithium battery; during the entire process, the internal splint basically does not deform, and the inner and outer splints are not squeezed at any time.

[0010] Another technical solution provided by the present invention is a metal lithium battery module, comprising a battery combination array, a binding wire and the above-mentioned consumable elastic splint; a consumable elastic splint is provided at each end of the battery combination array, and the binding wire is wrapped around the combination of the battery combination array and the consumable elastic splint, so that the two consumable elastic splints clamp the battery combination array in the expansion direction.

[0011] In the above-mentioned metal lithium battery module, the battery combination array is formed by arranging a number of battery cells, and the arrangement direction is the thickness direction of the battery cells.

[0012] The above-mentioned metal lithium battery module, wherein the battery combination array is formed by alternating a number of battery cells and a number of elastic foam pads, the arrangement direction is the thickness direction of the battery cells, and the outermost ends are both elastic foam pads. The elastic foam pads mainly play a role in the early stage of the charge and discharge cycle of the metal lithium battery module, and the expansion and contraction in the later stage of charge and discharge are realized by consumable elastic splints.

[0013] In the above-mentioned lithium metal battery module, the elastic foam pad is a closed-cell foam plastic, and the material is selected from polyethylene foam or polypropylene foam; when the lithium metal secondary battery is in a discharging state, the compression pressure of the elastic foam pad is 0.05Mpa to 0.12Mpa; when the lithium metal secondary battery is in a charging state, the compression pressure of the elastic foam pad is between 0.15Mpa and 0.4Mpa.

[0014] In the above-mentioned metal lithium battery module, the material of the binding wire is aramid fiber material; the cross-section of the binding wire is circular, with a diameter of 0.3mm to 0.4mm.

[0015] In the above-mentioned metal lithium battery module, a single binding wire is evenly and densely wound around the combination of the battery combination array and the consumable elastic clamping plate, and is wound in two layers.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are:

[0017] The present invention adopts a consumable elastic splint. The inner rigid splint of the consumable elastic splint is not affected by the deformation of the outer elastic splint, which can achieve uniform pressure on the battery combination array and avoid the problem of internal short circuit, fire and explosion caused by deformation of the internal single battery due to deformation of the splint.

[0018] The outer elastic splint of the present invention can provide an extrusion pressure far greater than that of the elastic foam. The increase in extrusion pressure is beneficial to the improvement of the charge and discharge cycle life of the metal lithium battery.

[0019] The foam middle consumption layer of the elastic splint of the present invention can collapse stably when subjected to a load exceeding its ultimate strength, further providing elastic space for the metal lithium battery, preventing the internal diaphragm of the metal lithium battery from short-circuiting due to abnormally high pressure, thereby protecting the diaphragm of the single battery.

[0020] The middle foam consumable layer of the consumable elastic splint of the present invention will be compressed as a whole under extremely high pressure, providing additional space for the battery combination array. It can also effectively prevent the outer elastic splint from breaking due to excessive pressure, and ensure the stability of the module structure during operation.

[0021] The consumable elastic splint of the present invention uses a multi-layer carbon fiber board as the outer layer, which has the advantages of light weight, high elasticity, large deformation, and adjustable elastic force compared to conventional rigid materials. The middle foam consumable layer uses high-density PMI material, which is not easy to break, has strong compressive resistance, and has a significantly improved compression modulus compared to conventional elastic foam materials, which can solve the problem of irreversible expansion of metal lithium batteries.

[0022] The present invention uses a wire binding method to tighten and fix the module array, which can achieve significant weight reduction of the structure compared to conventional pull rods, pull plates, etc., and the weight reduction effect achieved by using aramid fiber materials is particularly obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The consumable elastic splint and the metal lithium battery module of the present invention are described in the following embodiments and drawings.

[0024] Figure 1 Schematic diagram of the consumable elastic splint in Example 1 of the present invention.

[0025] Figure 2 Schematic diagram comparing the widths of the foam consumption layer and the outer elastic splint in Example 1 of the present invention.

[0026] Figure 3 This is a working principle diagram of the consumable elastic splint in Example 1 of the present invention.

[0027] Figure 4 Schematic diagram of a metal lithium battery module according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined Figures 1 to 4 The consumable elastic splint and the metal lithium battery module of the present invention are further described in detail.

[0029] Example 1:

[0030] The metal lithium battery module of this embodiment includes a battery combination array, a consumable elastic splint and a binding wire; a consumable elastic splint is provided at each end of the battery combination array, and the binding wire is wrapped around the combination of the battery combination array and the consumable elastic splint, so that the two consumable elastic splints clamp the battery combination array in the expansion direction.

[0031] In this embodiment, the battery combination array is formed by arranging a plurality of battery cells, and the arrangement direction is the thickness direction of the battery cells (ie, the direction in which the battery cells expand during the charging process).

[0032] Figure 1 Shown is a schematic diagram of a consumable elastic splint in embodiment 1 of the present invention.

[0033] See also Figure 1The consumable elastic splint of this embodiment includes an outer elastic splint 201, an intermediate foam consumable layer 202 and an inner rigid splint 203 bonded in sequence; the inner rigid splint 203 is adhered to the battery combination array.

[0034] In this embodiment, the material of the inner rigid plate 203 is selected from one of carbon fiber, aluminum alloy, and magnesium alloy; the inner rigid plate 203 is mainly used to shape the battery module and apply uniform pressure to the battery assembly array;

[0035] The width of the contact surface between the middle foam consumption layer 202 and the outer elastic splint 201 is smaller than the width of the outer elastic splint 201 and forms an elastic swing space for the outer elastic splint 201, such as Figure 2 The figure shows the relationship between two typical intermediate foam consumption layers 202 and the outer elastic splint 201. The hollow structure of the intermediate foam consumption layer 202 forms an elastic swing space for the outer elastic splint 201, thereby ensuring that the deformation of the outer elastic splint 201 does not affect the inner rigid splint 203.

[0036] The middle foam consumption layer 202 is made of high-density PMI material. The middle foam consumption layer 202 can withstand high pressure with only slight deformation. It will be compressed as a whole only under extremely strong pressure, thereby providing a space margin for the battery combination array and maintaining uniform and continuous pressure on the battery combination array. On the one hand, it prevents the outer elastic splint from excessive deformation and fracture. On the other hand, it can prevent excessive pressure on both sides of each single battery from causing each battery diaphragm to rupture, resulting in a short circuit in the battery and fire and explosion.

[0037] The material of the outer elastic splint 201 is carbon fiber, which is a multi-layer structure. The number of layers and the thickness of a single layer can be adjusted to change the maximum deformation amplitude of the outer elastic splint 201 and the elastic force generated by the deformation; the outer elastic splint with a smaller thickness has stronger elasticity and can undergo a larger deformation and rebound; the outer elastic splint with a larger thickness has poorer elasticity and can maintain the shape of the outer elastic splint to prevent excessive deformation; the outer elastic splint with a multi-layer structure adjusts the degree of elastic deformation by combining multiple elastic splints with different thicknesses to adapt to the tensile force of the binding wire driven by the expansion and contraction deformation of various battery combinations, and can share larger deformation variables through the multi-layer combination, reduce the deformation amplitude of a single layer, and prevent delamination or breakage due to excessive deformation.

[0038] Preferably, in the outer elastic splint 201 of the multi-layer structure, only the center position between each layer is the bonding and fixing area, and the remaining area is in a free state, in contact and allowed to slide, and the bonding and fixing area accounts for 10% to 50% of the total surface area; between the outer elastic splint 201 and the middle foam consumption layer 202, and between the middle foam consumption layer 202 and the inner rigid splint 203, only the center position is the bonding and fixing area, and the remaining area is in a free state, in contact and allowed to slide, and the bonding and fixing area accounts for 10% to 50% of the total surface area; the inner rigid splint 203 is connected to the battery combination array.

[0039] In this embodiment, the cross section of the inner rigid clamping plate 203 is a trapezoidal structure, and the larger surface of the inner rigid clamping plate 203 is bonded to the battery assembly array.

[0040] The binding wire is preferably made of aramid fiber material, which has very good tensile strength and can minimize the amount of binding wire used, thereby reducing weight; the cross-section of the binding wire is circular, and the diameter is preferably 0.3mm to 0.4mm; a single binding wire is evenly and densely wound on the combination of the battery combination array and the consumable elastic splint. This embodiment wraps two layers to achieve uniform force distribution of the binding wire, while avoiding hooking and pulling forces between the binding wires, so that the tensile force is only applied along the extension direction of the binding wire, greatly enhancing the safety and stability of the binding wire.

[0041] Figure 3 This is the deformation process of the consumable elastic splint as the metal lithium battery module charges and discharges. Figure 3 (A) The consumable elastic clamp is installed in the discharge state of the metal lithium battery module and provides a certain initial pressure; see Figure 3 (B) After the metal lithium battery module is fully charged, the outer elastic splint of the consumable elastic splint bends. After the outer elastic splint bends, both sides of the foam consumable layer are compressed and deformed; see Figure 3 (C) The lithium metal battery module is then discharged to a discharged state, and both sides of the foam consumable layer remain in a compressed and deformed state without recovering. In the subsequent cycles, the foam consumable layer basically maintains its previous state. As the number of cycles of the lithium metal battery module increases, the irreversible expansion of the lithium metal battery becomes more and more obvious, and the consumable elastic splint is gradually compressed as a whole to offset the irreversible expansion volume of the lithium metal battery. At this time, the deformation process of the elastic splint is shown in FIG. Figure 3 (D) and 3(E).

[0042] Example 2:

[0043] The difference between Example 2 and Example 1 is that the battery combination array of Example 2 is formed by alternatingly arranging a plurality of battery cells and a plurality of elastic foam pads, that is, an elastic foam pad is provided between two adjacent battery cells.

[0044] Figure 4 Shown is a schematic diagram of a metal lithium battery module according to a second embodiment of the present invention.

[0045] See also Figure 4 The metal lithium battery module of this embodiment includes a battery combination array 1, a consumable elastic clamp 2 and a pull wire 3.

[0046] See also Figure 2 and Figure 3 The battery combination array includes battery cells and elastic foam pads, which are arranged alternately in the direction of the battery cell thickness. The outermost ends are both elastic foam pads, and there is an elastic foam pad between two adjacent battery cells.

[0047] A consumable elastic splint 2 is provided at each end of the battery combination array 1. The consumable elastic splint 2 is bonded to the elastic foam pad at the outermost end; the binding wire 3 is wound around the combination of the battery combination array and the consumable elastic splint.

[0048] The consumable elastic splint 2 of Example 2 is identical to the consumable elastic splint of Example 1 and will not be described in detail.

[0049] The elastic foam pad is a closed-cell foam plastic, made of polyethylene or polypropylene. When the lithium metal secondary battery is in a discharged state, the elastic foam pad has a compression pressure of 0.05 MPa to 0.12 MPa; when the lithium metal secondary battery is in a charged state, the elastic foam pad has a compression pressure of 0.15 MPa to 0.4 MPa.

Claims

1. A metal lithium battery module, characterized in that: The battery assembly array comprises a battery assembly array, a binding wire, and a consumable elastic clamp; a consumable elastic clamp is provided at each end of the battery assembly array, and the binding wire is wound around the battery assembly array and the consumable elastic clamp, so that the two consumable elastic clamps clamp the battery assembly array in the expansion direction; The consumable elastic splint comprises an outer elastic splint, an intermediate foam consumable layer, and an inner rigid splint bonded in sequence. The width of the intermediate foam consumable layer is smaller than that of the outer elastic splint. A suspended space is directly constructed between the outer elastic splint and the inner rigid plate to provide a reciprocating deformation space for the outer elastic splint. The battery combination array is formed by arranging a number of battery cells in the direction of the thickness of the battery cells; the inner rigid clamping plate provides a flat extrusion surface for the ends of the internal single cells; The material of the middle foam consumption layer is a high-density foam material with a density of 0.1 g / cm 3 ~0.3g / cm 3 , the elastic modulus is between 100Mpa and 300Mpa.

2. The metal lithium battery module according to claim 1, characterized in that: The material of the inner rigid splint is selected from one of carbon fiber composite plate, aluminum alloy and magnesium alloy; the material of the outer elastic splint is selected from carbon fiber composite plate, which is a multi-layer structure.

3. The metal lithium battery module according to claim 2, characterized in that: The outer elastic splint of the multi-layer structure has only the center position between each layer as the bonding and fixing area, and the remaining area is in a free state, in contact and allowed to slide, and the bonding and fixing area accounts for 10% to 50% of the total surface area; between the outer elastic splint and the middle foam consumable layer, and between the middle foam consumable layer and the inner rigid splint, only the center position is the bonding and fixing area, and the remaining area is in a free state, in contact and allowed to slide, and the bonding and fixing area accounts for 10% to 50% of the total surface area.

4. The metal lithium battery module according to claim 1, wherein: The number of layers and the thickness of a single layer are adjusted to change the maximum deformation amplitude of the outer elastic splint and the magnitude of the elastic force generated by the deformation.

5. The metal lithium battery module according to claim 1, wherein: The material of the middle foam consumption layer is selected from high-density PMI material.

6. The metal lithium battery module according to claim 1, wherein: The battery combination array further comprises a plurality of elastic foam pads, the battery cells and the elastic foam pads are arranged alternately, and the outermost ends are both elastic foam pads.

7. The metal lithium battery module according to claim 6, characterized in that: The elastic foam pad is a closed-cell foam plastic, and the material is polyethylene foam or polypropylene foam; when the metal lithium secondary battery is in a discharging state, the compression pressure of the elastic foam pad is 0.05Mpa to 0.12Mpa; when the metal lithium secondary battery is in a charging state, the compression pressure of the elastic foam pad is between 0.15Mpa and 0.4Mpa.

8. The metal lithium battery module according to claim 1, wherein: The material of the binding wire is aramid fiber material; the cross section of the binding wire is circular, with a diameter of 0.3mm to 0.4mm; a single binding wire is evenly and densely wound around the combination of the battery combination array and the consumable elastic splint, with two layers of winding.

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