JP7479199B2 - Battery Cell - Google Patents

Description

The present invention relates to a battery cell, in particular a battery cell sealed with an exterior body.

In recent years, the demand for high-capacity, high-output battery devices has been rapidly expanding due to the widespread use of various large and small electric and electronic devices such as automobiles, personal computers, and mobile phones. Examples of such battery devices include liquid battery cells that use an organic electrolyte between the positive and negative electrodes, and solid battery cells that use a flame-retardant solid electrolyte instead of an organic electrolyte.

Among such battery devices, laminate cell type battery cells are known, in which the battery is wrapped in a laminate film (exterior body) and sealed in a plate shape. For applications such as EVs and HEVs, a battery cell assembly is used in which multiple such laminate cell type battery cells are arranged and stored in a case. Wrapping the battery in an exterior body can prevent air from entering the battery (for example, Patent Document 1). In this specification, the term "battery" refers to a member composed of a laminate of battery elements consisting of positive and negative electrodes and an electrolyte, and a current collecting tab lead, and a battery wrapped in a laminate film (exterior body) and sealed is called a "battery cell."

Also, a battery cell has been disclosed that includes an exterior body in which a single film is folded over to accommodate a battery, with the aim of effectively improving the volumetric energy density of a battery module while maintaining the airtightness of the laminate film (exterior body) (Patent Document 2). According to Patent Document 2, this battery cell can effectively improve the volumetric energy density of a battery module while maintaining the airtightness of the exterior body.

JP 2012-169204 A WO2019/188825

In battery cells in which the battery is covered with an exterior body made of laminate film, the laminate film alone does not have sufficient strength to protect the battery from external forces. Therefore, the rigidity of the battery cell cannot be said to be sufficiently high, and problems such as the electrodes of the battery cell cracking, particularly at the corners, have occurred. It is therefore possible to arrange reinforcing materials at the corners of the battery cell, but in that case, problems such as an increase in weight due to the increase in parts, a decrease in energy density due to the increase in volume, and an increase in the number of processes required to arrange the reinforcing materials arise.

In view of the above problems with battery cells, the present invention aims to increase the rigidity of the corners of a battery cell in which the battery is covered with an exterior body made of a laminate film, without providing additional reinforcing members, and to prevent the electrodes from cracking.

In order to solve the above problems, the battery cell of the present invention is a battery cell comprising a battery formed by stacking battery elements and an exterior body that houses the battery, and is characterized in that a current collector tab lead extends from one end face of the battery, the exterior body is made of a single film, and a rib structure is provided in which multiple sheets of the film are stacked at the corner of the side of the battery that is perpendicular to the end face from which the current collector tab lead extends.

By providing a rib structure in which multiple sheets of the film are stacked at the corners of the sides of the battery that are perpendicular to the end face on which the tab leads are extended, the corners are protected from external forces by two sheets of film without the need for additional reinforcing members, reducing the occurrence of problems with electrodes cracking at the corners.

In this case, the present invention is characterized in that the battery is surrounded and wrapped with one sheet of film, leaving some space between them, and then the excess portion is gathered and folded over to form the package.

The battery is wrapped around the single sheet of film with a generous margin, and then the excess portion is gathered and folded to form the rib structure, making effective use of the excess portion of the film and increasing the efficiency of resource (film) utilization. In addition, because the battery is wrapped around the single sheet of film with a generous margin, the risk of damaging the battery during the battery packaging process can be reduced.

Furthermore, in this case, the present invention is characterized in that the rib structure formed by stacking two sheets of film is formed by surrounding and packaging the battery with one sheet of film, and then vacuuming in a state in which the excess portion of the film is gathered at the corners of the battery so that the air inside the battery cell can be efficiently removed when vacuuming is performed, and after degassing, the excess portion of the film is pressed by the atmosphere to form a gathered portion, which is utilized to form the rib structure.

After the battery is surrounded and wrapped with the single sheet of film, the excess portion of the film is brought to the corner so that the air inside the battery cell can be efficiently removed. The rib structure is then formed using the assembled film portion that is formed after drawing a vacuum. This makes it possible to effectively utilize the excess portion of the film, improving the efficiency of resource (film) utilization, and also allows the rib structure to be formed in a simple process, improving manufacturing efficiency.

In addition, in this case, the present invention is characterized in that the rib structure formed by stacking multiple sheets of the film is folded in the direction opposite to the electrode surface side, toward the surface on which the battery element is stacked, and is fixed by thermal welding.

The rib structure is bent and fixed by heat welding, which reduces the risk of the movement of the rib structure damaging the battery when an external force is applied to the rib structure. In addition, because it is bent in the direction opposite to the electrode surface, toward the surface on which the battery elements are stacked, there is no problem of distortion of the electrode due to steps caused by the rib structure.

In this case, the present invention is characterized in that the single film of the exterior body comprises a portion that contacts and covers the top, bottom and two side surfaces perpendicular to the end surface from which the current collecting tab lead of the battery is extended, a portion that covers the end surface from which the current collecting tab lead of the battery protrudes, and is folded from the short sides of both sides of the end surface to form triangular pyramid-shaped spaces on both sides and folded from the long sides of both sides of the end surface to encase the end surface, and a portion that extends further in the axial direction from the portion that encases the end surface and joins both upper and lower opposing surfaces to sandwich the current collecting tab lead.

This type of exterior body made of a single film corresponds to a battery including the current collecting tab lead and the end surface from which the current collecting tab lead protrudes, and can efficiently encase and seal the end surface from which the current collecting tab lead protrudes, and can also cover and clamp the current collecting tab lead from both the top and bottom, making it possible to efficiently package a battery with a protruding current collecting tab lead with a small number of steps.

In this case, the present invention is characterized in that the battery is an all-solid-state battery made of a laminate using a solid electrolyte.

All-solid-state battery cells are fragile and easily damaged, especially at corners and end faces. Therefore, the configuration of the present invention, in which a rib structure is provided by stacking multiple sheets of the film at the corners of the sides of the battery that are perpendicular to the end faces to which the tab leads extend, is particularly effective when applied to all-solid-state battery cells.

According to the present invention, by providing a rib structure in which multiple layers of the film are stacked at the corners of the sides of the battery perpendicular to the end faces on which the tab leads are extended, it is possible to solve the technical problem of electrodes cracking at corners, particularly in solid-state batteries, without providing new reinforcing members.

FIG. 2 is a perspective view of a battery within a battery cell of the present invention. FIG. 1 is a perspective view showing the appearance of a battery cell of the present invention. FIG. 2 is a development view of an exterior body of a battery cell according to the present invention. FIG. 11 is a cross-sectional view of a corner of a conventional battery cell. FIG. 2 is a cross-sectional view of a corner of an embodiment of a battery cell of the present invention. 11 is a cross-sectional view of a corner of a battery cell according to another embodiment of the present invention. FIG.

One embodiment of the present invention will be described in detail below with reference to the drawings.

In the embodiment, the battery 1 of the present invention is an all-solid-state battery, and has a rectangular parallelepiped shape as shown in FIG. 1, with six faces: a top face 11a, a bottom face 11b, side faces 12a, 12b, and end faces 13a, 13b. When a central axis 15 is imagined connecting the centers of the end faces 13a and 13b, current collecting tab leads 14a and 14b are extended from the end faces 13a and 13b in the direction of the central axis 15. All-solid-state batteries are brittle and easily damaged, particularly at the corners and surface portions (end faces), and therefore are more suitable for applying the configurations of the various embodiments of the present invention.

Figure 2 shows a battery cell 2 in which the battery 1 in Figure 1 is covered and packaged with an exterior body 3. Note that Figure 2 does not clearly show the rib structure of the present invention, which is provided by overlapping the excess film portion of the exterior body 3. In other words, Figure 2 shows a conventional battery cell 2 in which the battery 1 in Figure 1 is covered and packaged with an exterior body 3.

The battery cell 2 also has a top surface 21a, bottom surface 21b, and side surfaces 22a, 22b defined to correspond to the battery 1. The locations corresponding to the end surfaces 13a, 13b of the battery 1 are end surface folded parts 23a-1, 23a-2, 23b-1, 23b-2 where the exterior body 3 is folded together, and the outer surface has a triangular prism shape. In addition, the end surface folded parts 23a-1, 23a-2 and 23b-1, 23b-2 have triangular pyramid-shaped spaces 25a-1, 25a-2 and 25b-1, 25b-2, which are folded in from the side surfaces 22a, 22b, respectively, and two spaces are formed on each side. Current collecting tab lead housing portions 24a-1, 24a-2 and 24b-1, 24b-2 that sandwich and house the current collecting tab leads 14a, 14b from above and below extend from the end face folding portions 23a-1, 23a-2 and 23b-1, 23b-2 in the direction of the central axis 15.

Figure 3 shows an exploded view of the exterior body 3. The exterior body 3 has a top cover portion 31a and a bottom cover portion 31b that cover the top surface 11a and bottom surface 11b of the battery 1, respectively, a side cover portion 32a that covers the side surface 12a, and side cover portions 32b-1 and 32b-2 that cover the side surface 12b. The side cover portions 32b-1 and 32b-2 are adhesive portions that overlap and are adhered to each other when the exterior body 3 encases the battery 1. Therefore, the side surface 12b of the battery 1 is doubly covered by the side cover portions 32b-1 and 32b-2 of the exterior body 3.

The end faces 13a, 13b of the battery 1 are covered by end face covering portions 33a-1, 33a-2, 33b-1, 33b-2, which form end face folding portions 23a-1, 23a-2, 23b-1, 23b-2 in the shape of a triangular prism formed by folding the exterior body 3 in the battery cell 2. Current collecting tab lead clamping portions 34a-1, 34a-2, 34b-1, 34b-2, which clamp the current collecting tab leads 14a, 14b on both sides from above and below, are provided at the ends of the end face covering portions 33a-1, 33a-2, 33b-1, 33b-2 extended in the direction of the central axis 15. In addition, triangular pyramidal space forming portions 35a-1, 35a-21, 35a-22 and 35b-1, 35b-21, 35b-22 are formed, which are the portions that form the triangular pyramidal space portions 25a-1, 25a-2 and 25b-1, 25b-2, respectively, that are formed by folding in from the side surfaces 22a and 22b. The triangular pyramidal space forming portions 35a-21 and 35a-22, and 35b-21 and 35b-22, respectively, overlap with each other to form triangular pyramidal spaces.

Figure 4 shows a cross-sectional view taken along the line IV-IV in Figure 2. The figure shows a battery 1 formed by stacking battery elements, covered by an exterior body 3. However, in conventional battery packs, as shown in Figure 4, even at the corners of the battery 1, only one laminate film of the exterior body 3 covers the battery. This is not strong enough to protect the corners of fragile batteries, such as solid-state batteries, from external forces.

Figure 5 shows a conventional battery cell 2 in Figure 4, in which a rib structure 4 is formed by stacking two films of the exterior body 3 at the corners of the battery 1 of the present invention. The rib structure 4 is formed by stacking two films of the exterior body 3, and serves as a reinforcing part for the corners of the battery 1, protecting the battery 1 from external forces.

The rib structure 4 in Figure 5 can be formed by wrapping the battery 1 with a single sheet of film, leaving a generous margin, and then gathering up the excess. This allows the excess portion of the film of the exterior body 3 to be used effectively, improving the efficiency of resource (film) usage, and also reduces the risk of damaging the battery 1 during the wrapping process, since the battery 1 is wrapped with a single sheet of film, leaving a generous margin.

The rib structure 4 in Fig. 5 can be formed by surrounding and packaging the battery 1 with a single sheet of film, then drawing a vacuum by bringing the excess film into contact with the corners of the battery 1, allowing the air inside the battery cell to be efficiently removed. This allows the excess film of the exterior body 3 to be used effectively, improving the efficiency of resource (film) utilization, while also allowing the rib structure 4 to be formed in a simple process, improving manufacturing efficiency.

More preferably, the rib structure 4 shown in FIG. 5 is further folded in the direction opposite to the electrode surface side, toward the surface on which the battery elements are stacked, and fixed by heat welding, as shown in FIG. 6. By folding the rib structure 4 and fixing it by heat welding, the rib structure 4 maintains its structure even when an external force is applied to the rib structure 4, and the risk of damaging the battery due to the displacement or slippage of the exterior film within the rib structure 4 can be reduced. Note that, when the rib structure 4 is folded toward the electrode surface side, a step is created in the exterior body 3 above the electrode surface due to the part where the rib structure 4 is present and the part where it is not present, and this step may apply an external force to the electrode, causing damage, which is not preferable.

The above describes the manner in which the present invention can be implemented using examples, but the present invention is not limited to these examples, and it goes without saying that the present invention can be implemented in various ways without departing from the spirit of the invention.

LIST OF SYMBOLS 1 Battery 11a Top surface 11b Bottom surface 12a, 12b Side surface 13a, 13b End surface 14a, 14b Current collecting tab lead 15 Central axis 2 Battery cell 21a Top surface 21b Bottom surface 22a, 22b Side surface 23a-1, 23a-2, 23b-1, 23b-2 End surface folded portion 24a-1, 24a-2, 24b-1, 24b-2 Current collecting tab lead housing portion 25a-1, 25a-2, 25b-1, 25b-2 Triangular pyramid-shaped space portion 3 Exterior body 31a Top surface cover portion 31b Bottom surface cover portion 32a, 32b-1, 32b-2 Side surface cover portion 33a-1, 33a-2, 33b-1, 33b-2 End surface cover portion 34a-1, 34a-2, 34b-1, 34b-2 Current collector tab lead clamping portion
35a-1, 35a-21, 35a-22, 35b-1, 35b-21, 35b-22
Triangular pyramid-shaped space forming portion 4 Rib structure

Claims (5)

A battery cell including a battery formed by stacking battery elements and an exterior body that houses the battery,
A current collecting tab lead is extended from one end surface of the battery,
the exterior body is made of a single film, and a rib structure is provided at a corner of a side perpendicular to an end face to which the current collecting tab lead of the battery is extended, the rib structure being provided by stacking a plurality of the films;
The rib structure, which is formed by stacking multiple films, is formed by surrounding and packaging the battery with one sheet of film, and then gathering the excess portion of the film at the corner of the battery so that the air inside the battery cell can be efficiently removed when the vacuum is drawn, and after degassing, the excess portion of the film is pressed by the atmosphere to form a gathered portion, which is used to create the rib structure of the battery cell. The battery cell according to claim 1 , wherein the excess portions gathered at the corners are fixed by thermal welding. 3. The battery cell according to claim 1, wherein the excess portion gathered at the corner is folded in the direction opposite to the electrode surface side, that is, in the direction of the surface on which the battery elements are stacked, and fixed by thermal welding. 4. The battery cell according to claim 1, wherein the single film of the exterior body comprises: a portion that contacts and covers a top surface, a bottom surface, and two side surfaces perpendicular to the end surface from which the current collecting tab lead of the battery extends; a portion that covers the end surface from which the current collecting tab lead of the battery protrudes, and which is folded from short sides on both sides of the end surface to form triangular pyramid-shaped spaces on both sides and is folded from long sides on both sides of the end surface to encase the end surface; and a portion that extends further in the axial direction from the portion encasing the end surface to join both upper and lower opposing surfaces to sandwich the current collecting tab lead. 5. The battery cell according to claim 1 , wherein the battery is an all-solid-state battery made of a laminate using a solid electrolyte.

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