Energy storage module
By integrating an organic lubricant into the PET-based heat-shrinkable material and employing partial separator contact, the energy storage module maintains electrical insulation integrity in high-temperature and high-humidity environments, addressing the issue of hole formation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- PRIME PLANET ENERGY & SOLUTIONS INC
- Filing Date
- 2024-11-07
- Publication Date
- 2026-05-19
AI Technical Summary
In high-temperature and high-humidity environments, aluminum and polyethylene terephthalate (PET) in the insulating protective heat-shrinkable material of electricity storage modules form hydrogen bonds, leading to hole formation and compromised electrical insulation.
Incorporating an organic lubricant, such as a fatty acid-based lubricant, into the PET-based heat-shrinkable insulating material, along with partial contact of the separator with the side surface, to prevent adhesion and reduce stress concentration, thereby minimizing hole formation.
The solution provides long-term electrical insulation protection by preventing holes in the insulating material, even under harsh conditions, ensuring effective insulation performance.
Smart Images
Figure 2026082211000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to an electricity storage module.
Background Art
[0002] Patent Document 1 proposes a heat-shrinkable aromatic polyester tube as an electrical insulating material for a lithium ion battery.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] When an electricity storage module composed of an electricity storage cell covered with an insulating protective heat-shrinkable material containing polyethylene terephthalate (PET) and a separator is used in a high-temperature and high-humidity environment, aluminum and PET may form a hydrogen bond, and holes may be formed in the insulating protective heat-shrinkable material due to the tensile load caused by the post-shrinkage of PET. As a result, it becomes difficult to obtain electrical insulation protection in the electricity storage module.
[0005] An object of the present disclosure is to provide an electricity storage module in which holes are less likely to form in the insulating protective heat-shrinkable material even when used in a high-temperature and high-humidity environment.
Means for Solving the Problems
[0006] [1] An electricity storage module including an electricity storage cell and a separator, where the electricity storage cell includes an outer can and an insulating protective heat-shrinkable material, the outer can is made of aluminum, and the insulating protective heat-shrinkable material contains polyethylene terephthalate and an organic lubricant. [2] The energy storage cell has a top surface, a bottom surface, and a side surface located between the top surface and the bottom surface, The energy storage module according to [1], wherein the outer casing is covered with the insulating heat-shrinkable material on the side surface, or on both the bottom surface and the side surface. [3] The separator is positioned in partial contact with the side surface, The energy storage module according to [2], wherein two or more fixing portions are formed in which the insulating protective heat shrink material is fixed to the outer casing by the separator. [4] The energy storage module according to any one of the items [1] to [3], wherein the heat shrink material for insulating protection is not fully shrunk. [5] The energy storage module according to any one of [1] to [4], wherein the content of the organic lubricant in the heat shrink material for insulating protection is 0.5% by mass or more and 10% by mass or less. [6] The energy storage module according to any one of [1] to [5], wherein the organic lubricant comprises a fatty acid-based lubricant. [7] The energy storage module according to [6], wherein a film containing a fatty acid-based lubricant is formed on the energy storage cell side surface of the heat shrinkable insulating material. [Effects of the Invention]
[0007] According to this disclosure, it is possible to provide an energy storage module in which holes are less likely to form in the heat-shrinkable insulating protective material even when used in a high-temperature, high-humidity environment. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 shows an example of the basic configuration of an energy storage module. [Figure 2] Figure 2 shows a battery pack containing energy storage cells. [Figure 3] Figure 3 is a schematic cross-sectional view of the energy storage modules as seen from a direction perpendicular to the arrangement direction and height direction. [Figure 4] Figure 4 is a schematic cross-sectional view illustrating the area near the hydrogen bonding region of the energy storage cell. [Figure 5]Figure 5 is a schematic cross-sectional view of the area near the hydrogen bond in Figure 4, magnified. [Figure 6] Figure 6 shows another basic configuration example of an energy storage module. [Figure 7] Figure 7 is a schematic diagram illustrating a method for evaluating the presence or absence of holes in the heat-shrinkable insulating material used for energy storage cells. [Modes for carrying out the invention]
[0009] The energy storage module of this disclosure comprises an energy storage cell and a separator. The energy storage cell comprises an outer casing and a heat-shrinkable insulating protective material. The outer casing is made of aluminum. The heat-shrinkable insulating protective material comprises PET and an organic lubricant.
[0010] Figure 1 is a perspective view of an energy storage module. The energy storage module 100 shown in Figure 1 comprises energy storage cells 10 and separators 20. The energy storage cells 10 and separators 20 are arranged alternately along the arrangement direction (Y-axis direction).
[0011] The energy storage cells 10 are rectangular battery cells, and multiple cells are arranged along the direction of arrangement. The energy storage cells 10 may be, for example, lithium-ion batteries, nickel-metal hydride batteries, etc. Multiple energy storage cells 10 are electrically connected to each other via busbars (not shown).
[0012] The separator 20 is installed between multiple energy storage cells 10. The separator 20 prevents unintended electrical conduction between adjacent energy storage cells 10. The separator 20 ensures electrical isolation between adjacent energy storage cells 10.
[0013] As shown in Figure 2, the energy storage cell 10 is formed in a flat, rectangular parallelepiped shape. The energy storage cell 10 comprises an outer casing 11 and an insulating, heat-shrinkable material 12. The outer casing 11 is made of aluminum. The outer casing 11 contains electrodes and an electrolyte (not shown).
[0014] The storage battery cell 10 can have a top surface 10A, a bottom surface 10C, and a side surface 10B located between the top surface 10A and the bottom surface 10C. The side surface 10B may be composed of a long side surface 10D and a short side surface 10E. The long side surface 10D can be a side surface perpendicular to the arrangement direction (Y-axis direction). The storage battery cell 10 has a terminal portion. Positive electrode terminal 13 and negative electrode terminal 14 may be formed on the top surface 10A of the storage battery cell 10.
[0015] From the viewpoint of achieving electrical insulation protection, the outer can 11 is covered with a heat-shrinkable material 12 for insulation protection. The outer can 11 is covered with the heat-shrinkable material for insulation protection on both the bottom surface 10C and the side surface 10B, or is covered with the heat-shrinkable material for insulation protection on the side surface 10B. The bottom surface 10C may not be covered with the heat-shrinkable material for insulation protection. That is, the five surfaces of the outer can 11 other than the top surface 10A (terminal portion) may be covered with the heat-shrinkable material for insulation protection, or only the four side surfaces 10B may be covered with the heat-shrinkable material for insulation protection. By covering the outer can 11 with the heat-shrinkable material for insulation protection, electrical insulation protection is ensured. The top surface 10A (terminal portion) is usually not covered with the heat-shrinkable material for insulation protection.
[0016] The heat-shrinkable material 12 for insulation protection may be, for example, in the form of a tape, a film, a tube, or the like. The shape of the heat-shrinkable material 12 for insulation protection before covering the outer can 11 is not particularly limited as long as it can cover the outer can 11. The heat-shrinkable material 12 for insulation protection can cover the outer can 11, for example, by shrinking due to heat sealing. The heat-shrinkable material 12 for insulation protection may be manufactured by a conventionally known method.
[0017] The insulating heat-shrinkable material 12 contains PET from the viewpoint of heat shrinkability. The insulating heat-shrinkable material 12 further contains an organic lubricant. When an aluminum outer casing is covered with an insulating heat-shrinkable material made of PET that does not contain an organic lubricant, when used in a high-temperature, high-humidity environment, multiple energy storage cells and multiple separators are arranged in close contact, causing hydrogen bonding between the aluminum and PET. This can lead to tensile loads due to post-expansion and contraction of the insulating heat-shrinkable material, which may cause holes to form in the insulating heat-shrinkable material. In the energy storage module of this disclosure, by including an organic lubricant in the insulating heat-shrinkable material made of PET, adhesion between the outer casing and the insulating heat-shrinkable material is prevented, and stress concentration due to post-expansion and contraction of the insulating heat-shrinkable material is less likely to occur. As a result, holes are less likely to form in the insulating heat-shrinkable material in a high-temperature, high-humidity environment, and electrical insulation protection tends to be obtained more easily over a long period of time.
[0018] Under high temperature and high humidity conditions, it is presumed that aluminum and PET will form hydrogen bonds in the following steps (1) to (3): (1) First, condensation water generates aluminum hydroxide (-OH group) on the surface of the outer can. (2) High temperature drying causes some of the condensation water to evaporate. (3) Under high temperature conditions, the movement of PET molecules becomes more active, causing hydrogen bonding between the hydroxyl group (-OH group) and the oxygen atom (O) of the PET molecule, promoting adhesion. On the other hand, under high temperature and high humidity conditions, the organic lubricant is more likely to bleed out onto the surface of the insulating heat shrink material due to the activation of PET molecules. As a result, a film containing the organic lubricant is more easily formed between the surface of the outer can and the insulating heat shrink material. This makes it easier to suppress adhesion between the insulating heat shrink material and the outer can, making it less likely for holes to form in the insulating heat shrink material under high temperature and high humidity conditions, and as a result, it is presumed that electrical insulation protection can be obtained for a longer period of time.
[0019] Examples of organic lubricants include fatty acid-based lubricants. When the organic lubricant is a fatty acid-based lubricant, a film containing the fatty acid-based lubricant may be formed on the energy storage cell 10 side surface of the insulating protective heat shrink material 12. From the viewpoint of bleed-out, stearic acid is preferred as the fatty acid-based lubricant.
[0020] The content of the organic lubricant in the insulating heat-shrinkable material 12 may be, for example, 0.5% by mass or more. When the content of the organic lubricant is within the above range, adhesion between the outer can and the insulating heat-shrinkable material tends to be easily prevented. From the viewpoint of adhesion between the outer can and the insulating heat-shrinkable material, electrical insulation, and heat shrinkage, the content of the organic lubricant in the insulating heat-shrinkable material 12 is preferably 0.5% by mass or more and 10% by mass or less.
[0021] Figure 3 is an example of a schematic cross-sectional view of the energy storage module 100 as seen from a direction X perpendicular to the arrangement direction Y and height direction Z. As shown in Figure 3, the separator 20 is positioned in contact with the side surface 10B. The separator 20 may be positioned in partial contact with the side surface 10B. By positioning the separator 20 in partial contact with the side surface 10B, it is easier to suppress the accumulation of condensation water between the energy storage cell 10 and the separator 20, which can cause electrical leakage when the energy storage module 100 is used in a high-temperature, high-humidity environment. In addition, by positioning the separator 20 in partial contact with the side surface 10B, cooling air for cooling the heated cell 10 can be passed through the gap between the side surface 10B and the separator 20.
[0022] As shown in Figure 3, the separator 20 may be positioned so as to be partially in contact with the side surface 10B when viewed from a direction perpendicular to the arrangement direction (Y-axis direction) and the height direction (Z-axis direction) (X-axis direction). The separator 20 may have grooves, recesses, openings, protrusions, or combinations thereof formed on the side that is in contact with the side surface 10B. By forming grooves, recesses, openings, protrusions, or combinations thereof on the side of the separator 20 that is in contact with the side surface 10B, the separator 20 can be positioned so as to be partially in contact with the side surface 10B. The shape of the separator 20 when viewed from the X-axis direction may be a rectangular wave shape, as shown in Figure 3.
[0023] The energy storage cell 10 may have two or more fixing portions 15 formed in which an insulating protective heat shrink material 12 is fixed to the outer casing 11 by a separator 20. As shown in Figure 4, the fixing portions 15 can be formed by the three-dimensional shape (e.g., grooves, recesses, openings, protrusions, and combinations thereof) of the side of the separator 20 that is in contact with the side 10B of the separator 20, so that the separator 20 is positioned in partial contact with the side 10B. In a high temperature and high humidity environment, when hydrogen bonding portions 16 formed between aluminum and PET occur between two fixing portions 15, the insulating protective heat shrink material 12 tends to develop very small holes. The initial hydrogen bonding between aluminum and PET is at only a few points, and the strength of the bond is weak. As shown in Figure 5, if a hydrogen bond 16 is formed between two fixed parts 15, it is presumed that in a high-temperature, high-humidity environment, the insulating heat-shrinkable material 12, which is not fixed by the separator 20, will shrink, and a tensile load F will be applied to the hydrogen bond, causing the hydrogen bond to easily break and creating tiny holes in the insulating heat-shrinkable material 12. However, according to this disclosure, since the insulating heat-shrinkable material contains an organic lubricant, adhesion between the outer can and the insulating heat-shrinkable material is prevented, making it less likely for hydrogen bonds to form, and even when two or more fixed parts 15 are formed, it is less likely for holes to form in the insulating heat-shrinkable material.
[0024] The heat-shrinkable insulating material 12 may be fully shrunk or not. According to this disclosure, because the heat-shrinkable insulating material contains an organic lubricant, adhesion between the outer can and the heat-shrinkable insulating material is prevented, and even if the heat-shrinkable insulating material shrinks in a high-temperature, high-humidity environment, holes are less likely to form.
[0025] The material constituting the separator 20 may include, for example, a thermoplastic resin. Examples of thermoplastic resins include polypropylene resins, polyethylene resins, polybutylene resins, polyamide resins, polyolefin resins, acrylic resins, urethane resins, and the like.
[0026] Figure 6 shows another example of the energy storage module of the present disclosure. The energy storage module 200 shown in Figure 6 has energy storage cells 10 and separators 20 stacked alternately. The energy storage cells 10 and separators 20 may be sandwiched and fixed between a pair of end plates 30. Multiple energy storage cells 10 sandwiched between two end plates are pressed by the end plates 30 and constrained between the two end plates 30.
[0027] The end plates 30 are positioned at both ends of the energy storage module 200 in the arrangement direction (Y direction). The end plates 30 are fixed to a base such as a case that houses the energy storage module 200. Stepped portions 41 are formed at both ends of the end plates 30 in the X direction.
[0028] The fastening portion 50 includes a restraining member 51 that connects the two end plates 30 to each other, and a cover member 52 provided at the corners of the end plates 30. The restraining member 51 is attached to the stepped portion 41 formed on each of the two end plates 30. In the example shown in Figure 6, the restraining member 51 has a substantially L-shaped cross-section, and the restraining member 51 is positioned at the corner of the energy storage cell 10.
[0029] When a compressive force in the direction of arrow Y is applied to the stack of multiple energy storage cells 10, separators 20, and end plates 30, the restraining member 51 is engaged with the stepped portion 41, and then the compressive force is released, causing a tensile force to act on the restraining member 51 connecting the two end plates 30. In reaction to this, the restraining member 51 presses the two end plates 30 closer together.
[0030] The end plate 30 is made of, for example, die-cast aluminum, extruded aluminum, or cast iron. The restraining member 51 is made of, for example, general materials such as SPFH590 and stainless steel.
[0031] While embodiments of the present disclosure have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present disclosure is defined by the claims and is intended to include all modifications in the sense and scope equivalent to the claims.
[0032] The present invention will be described in more detail below with reference to examples. [Examples]
[0033] <Example 1> A power storage module 100 consisting of a power storage cell 10 and a separator 20, as shown in Figure 3, was prepared. As shown in Figure 3, the separator 20 of the power storage module 100 is partially in contact with the power storage cell 10 when viewed from a direction perpendicular to the arrangement direction (Y-axis direction) and height direction (Z-axis direction) (X-axis direction). This creates two or more fixing points where the insulating protective heat shrink material 12 is fixed to the outer casing 11. The outer casing 11 constituting the power storage cell 10 is made of aluminum, and its sides are covered with a tubular insulating protective heat shrink material 12 containing PET and a fatty acid-based lubricant. After the power storage module 100 was subjected to condensation (water absorption) and drying repeated two or more times in a high-temperature, high-humidity environment, the power storage cell 10 was removed from the power storage module 100. The presence or absence of holes in the insulating protective heat shrink material 12 was evaluated according to the following procedure.
[0034] As shown in Figure 7, the energy storage cell 10 was immersed in water 300, and a voltage of 500V was applied to measure the insulation resistance between the energy storage cell and the water using an insulation resistance meter 400. If there is a hole in the heat shrink material 12 for insulation protection, the insulation resistance decreases when water is interposed in the hole. This makes it possible to confirm the presence or absence of holes in the heat shrink material 12 for insulation protection, even if there are minute holes in the heat shrink material 12 that cannot be seen with the naked eye.
[0035] Based on the above evaluation, no decrease in insulation resistance was observed. Therefore, it is determined that there are no holes in the heat-shrinkable insulating material 12. According to this disclosure, it is possible to obtain an energy storage module that provides long-term electrical insulation protection. [Explanation of Symbols]
[0036] 10 Energy storage cell, 10A Top surface, 10B Side surface, 10C Bottom surface, 10D Long side surface, 10E Short side surface, 11 Outer casing, 12 Heat shrink material for insulation protection, 13 Positive terminal, 14 Negative terminal, 15 Fixing part, 16 Hydrogen bonding part, 20 Separator, 30 End plate, 41 Stepped part, 50 Fastening part, 51 Restraining member, 52 Cover member, 100, 200 Energy storage module, 300 Water, 400 Insulation resistance meter, F Tensile load.
Claims
1. A storage module comprising a storage cell and a separator, The aforementioned energy storage cell comprises an outer casing and a heat-shrinkable material for insulating protection. The outer can is made of aluminum. The aforementioned heat-shrinkable insulating material comprises polyethylene terephthalate and an organic lubricant, in an energy storage module.
2. The energy storage cell has a top surface, a bottom surface, and a side surface located between the top surface and the bottom surface. The energy storage module according to claim 1, wherein the outer casing is covered with the insulating protective heat shrink material on the side surface, or on both the bottom surface and the side surface.
3. The separator is positioned in partial contact with the side surface, The energy storage module according to claim 2, wherein two or more fixing portions are formed in which the heat-shrinkable insulating protective material is fixed to the outer casing by the separator.
4. The energy storage module according to claim 1, wherein the heat-shrinkable insulating protective material is not completely shrunk.
5. The energy storage module according to claim 1, wherein the content of the organic lubricant in the heat-shrinkable insulating material is 0.5% by mass or more and 10% by mass or less.
6. The energy storage module according to claim 1, wherein the organic lubricant includes a fatty acid-based lubricant.
7. The energy storage module according to claim 6, wherein a coating containing a fatty acid-based lubricant is formed on the energy storage cell side surface of the heat shrinkable insulating protective material.