CH713315A2 - Battery, in particular button cell, and its manufacturing process. - Google Patents

Abstract

The present invention relates to a method of manufacturing a battery, in particular a button cell, comprising two parts (3, 4) respectively defining the two poles of the battery. It is characterized in that two respective surfaces of the two parts (3, 4), arranged facing one another, are assembled with a layer of insulating adhesive (2) having a thickness controlled by means of a spacer (1A) made of insulating material. This spacer is formed for example of ceramic particles. It can also be formed of a lattice incorporated in the insulating glue. In another embodiment, the spacer may be formed by studs deposited, prior to bonding, on one of the two surfaces to be bonded.

Description

Description

OBJECT OF THE INVENTION

The present invention relates to a battery manufacturing process and in particular button cells. It also relates to the battery resulting from the aforementioned manufacturing process.

TECHNOLOGICAL BACKGROUND

The button cells generally comprise a housing provided with a container and a lid respectively forming the positive and negative poles of the battery. Conventionally, the two parts are assembled via a preformed polymer gasket ensuring the tightness of the battery and ensuring the function of galvanic isolation between the two poles. Such a construction is shown, for example, in GB 1,566,061.

This joint assembly has the disadvantage of occupying a non-negligible space that will restrict the active volume of the battery containing the electrolyte. In addition, it requires a step of folding the upper part of the container against the lid to compress the polymer seal and ensure the closure and sealing of the button cell.

To overcome these disadvantages, one solution is to assemble the container and the lid by bonding without adding a preformed seal. However, in the particular case of an application for batteries, the method of assembly of the battery case must meet several criteria that can be listed as follows: - Guarantee a minimum thickness of the adhesive layer that is sufficient to ensure the non-contact of the poles and thus a good galvanic isolation; - Guarantee a uniform thickness of the adhesive layer to ensure a constant strength of the bonding; - Guarantee this minimum and homogeneous thickness of the adhesive layer regardless of its consistency, whether rather viscous or fluid; - Ensure the reproducibility of the process to ensure the dimensions of the final assembly from one pile to another.

To date, it is difficult to implement a battery manufacturing process with a glue of controlled thickness which is simple, consistent with a high rate and mass production and therefore ultimately inexpensive.

SUMMARY OF THE INVENTION

The present invention provides a novel method of manufacturing a battery for controlling the thickness of a glue joint connecting the two poles to ensure the functions of galvanic isolation, resistance and sealing between the two parts respectively forming the two poles. The invention also relates to a battery, in particular a button cell resulting from the manufacturing process.

For this purpose, a manufacturing method and a battery according to the appended claims are proposed.

BRIEF DESCRIPTION OF THE FIGURES

The features and advantages of the present invention will appear on reading the detailed description below with reference to the following figures:

Figs. 1a, 1b show schematically the steps implemented during the assembly of the two parts of the battery case according to a first variant of the invention.

Figs. 2a, 2b, 2c show schematically the steps implemented during assembly according to a second variant of the invention.

Fig. 3 is a half-sectional view of an arrangement of the contiguous area between the container and the battery case lid after assembly in accordance with the present invention.

Fig. 3a is an enlargement of the contiguous zone.

Figs. 4 and 4a show a variant of the arrangement according to FIGS. 3 and 3a. Key [0009] (1) Spacer (2) Adhesive layer (3) First part of the housing, in particular cover, defining a pole (4) Second part of the housing, in particular container, defining the other pole (5) Joint bonded (6) Housing (7) Polymer seal

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method of manufacturing a battery comprising a housing conventionally provided with two parts defining its poles. It may be a button cell but the present invention is applicable to other types of batteries such as bag batteries, thin film batteries, and more generally all types of batteries assembled in the prior art. by crimping compressing a preformed polymeric seal. The present invention also relates to the battery resulting from this manufacturing process.

According to the invention, the junction between two surfaces of these parts is provided by an insulating adhesive layer comprising a spacer for maintaining the bonded surfaces at a given distance substantially constant. Here spacer means both a set of elements distributed in the junction, such as particles, a continuous structure such as a lattice incorporated in the adhesive layer.

According to the invention, this spacer has a series of characteristics that makes it suitable for use in a battery without altering the resistance of the junction, the sealing of the housing or the galvanic isolation of the battery.

Thus, the spacer is made of an electrically insulating material, chemically stable and compatible with the chosen type of glue. Advantage will also be taken of compatibility with the electrolyte present in the cell. Preferably, the material also has a density close to that of the adhesive in order to avoid a phenomenon of sedimentation or flotation in the case of a spacer in the form of particles. The material must also be resistant to compression to allow strong bonding, i.e. under pressure, substantially without deformation of the spacer. As a result, the material of the spacer is preferably chosen from among glasses, ceramics (carbides, nitrides, oxides) and diamond, but also from polymers and composites with an organic matrix. More particularly, mention may be made of alumina as a ceramic choice and Teflon, PEEK, PET and nylon as the choice of polymers. To improve the wettability of the spacer in the adhesive, it is furthermore possible to perform a surface treatment of this spacer.

The spacer may take different forms. It may be in the form of particles, in particular beads, in the form of a structure of the fabric or mesh type, or in the form of pads deposited on one of the surfaces to be bonded. The size of the spacer is chosen according to the thickness of the desired adhesive layer after polymerization. To ensure the non-contact between the assembled poles to obtain a galvanic isolation, the adhesive layer must have a thickness of at least 30 μm, preferably substantially 50 μm. Preferably, it does not exceed 200 μm in order to produce a seal of limited thickness. In the case of deposited pads, their thickness is therefore at least 30 pm as in the case of particles. The latter preferentially have an average diameter d 50 of between 30 μm and 200 μm with a variation around this average size, preferably between 10% and 25%.

Always preferentially, the particles are not perfectly spherical beads but have angular edges and surface which are as many attachment sites during bonding. In addition, a certain surface roughness is advantageous. These angular shapes also prevent relative movement of the parts to be assembled by rolling balls or particles during the application of pressure during the polymerization phase.

The density of particles forming the spacer and their distribution are determined to obtain a substantially constant thickness along the length of the junction. In the case of a set of elements such as balls or pads, they are advantageously distributed over the length of the bonded joint with a density of between 1 and 20 per mm 2 and, preferably, between 5 and 10 per mm 2. In the case of a fabric type continuous structure, it extends substantially over the entire length of the junction and advantageously over most of its width. In the latter case, we will choose a fabric that is well wetted by the glue to form an impermeable interface with the glue. In particular, it will be ensured that the fibers do not form fibrils that can act as wicks and therefore path for the electrolyte.

As regards the adhesive, it is preferably an epoxy glue or an acrylate glue. Other types of glue can be envisaged, for example silicone or polyurethane glues.

According to the invention, there are several ways to incorporate the spacer in the adhesive layer forming the insulating junction during assembly of the two parts of the housing to be bonded. The type of spacer will be chosen accordingly.

According to a variant schematically represented in FIGS. 1a and 1b, the spacer 1 is integrated in the glue 2 before removal. In this configuration, the spacer may be in the form of dispersed particles within the glue. For example, it is possible to use dispersed glass beads in a glue film or a more liquid adhesive, and this is well known to those skilled in the art. The spacer may also be in the form of a fibrous structure pre-impregnated with glue (not shown). When the glue creeps, under the effects of gluing pressure

Claims (16)

or the polymerization temperature, the spacer serves as a mounting stop between the two parts 3 and 4 as shown sequentially in FIGS. 1a and 1b. This ensures the accuracy and repeatability of the assembly. According to another variant shown in FIGS. 2a, 2b and 2c, the steps of removing the glue and the spacer are distinct. The spacer 1 is deposited on one of the two surfaces to be bonded (FIG 2a) or on both surfaces. In this configuration, the spacer may be in the form of pads deposited by a printing process, in particular by screen printing, by spray or by pad printing. Then, the adhesive layer 2 is deposited on the surface of one of the parts 3 or 4 (FIG 2b). The pads deposited allow, after solidification, to achieve a stop when assembling the two parts 3, 4 of the stack (Figure 2c). The spacer may also be in the form of a structure or particles deposited on one of the surfaces possibly already covered with a film of glue. It is also conceivable to sandwich the structure or the particles between two glue films. The structure is deposited or the particles are sprinkled on a first glue film before depositing a second glue film allowing a perfect coating of the spacer. The insulating junction between the two parts of the battery can be made at different locations of this housing. As non-limiting examples, FIGS. 3, 3a and 4, 4a show different arrangements of the junction glued between the two parts. In fig. 3, the junction 5 bonded between the lid 3 and the container 4 is positioned on the cylindrical periphery of the housing 6 with the base of the lid 3 a polymer gasket 7 insulating the lid of the container. In a preferred variant shown in FIG. 4, the bonded junction 5 between the lid 3 and the container 4 is positioned in a frustoconical zone of the housing 6 located in its upper part. The battery case thus produced has the advantage of having an optimized active volume, compared to a conventional housing having a preformed polymer seal, while being waterproof and having good galvanic isolation. claims A method of manufacturing a battery, in particular a button cell, comprising two parts (3, 4) respectively defining the poles of the battery, these two parts being assembled by means of a layer of adhesive (2) arranged between two respective surfaces of the two parts arranged one opposite the other, this manufacturing method being characterized in that said layer of glue has a controlled thickness by means of a spacer (1) of electrically insulating material, this layer of glue forming after polymerization an electrically insulating joint between the two parts. 2. Method according to claim 1, characterized in that the spacer (1) is integrated with the glue before assembly of the two parts. 3. Method according to claim 1, characterized in that the spacer (1) and the adhesive layer (2) are deposited separately during assembly. 4. Method according to any one of the preceding claims, characterized in that the spacer (1) is in the form of particles. 5. Method according to any one of claims 1 to 3, characterized in that the spacer (1) is formed by a structure such as a lattice or a fabric. 6. Method according to any one of the preceding claims, characterized in that the spacer (1) is, during assembly, sandwiched between two adhesive films forming after polymerization said adhesive layer (2). 7. Method according to claim 1 or 3, characterized in that the spacer (1) is in the form of pads. 8. The method of claim 7, wherein the pads are deposited, before assembly of the two parts, on one or both surfaces to be bonded by a printing process, including pad printing, screen printing or spray. 9. Method according to one of claims 4, 7 and 8, characterized in that the density of the pads or particles is between 1 and 20 particles / pads per mm 2 and preferably between 5 and 10 particles / pads per mm 2 surfaces to assemble. 10. Process according to any one of the preceding claims, characterized in that the spacer (1) has a thickness or a mean diameter (d50) of at least 30 μm. 11. Method according to any one of the preceding claims, wherein the spacer (1) is made of a material selected from glasses, ceramics, diamond and polymer matrix composites. 12. Battery, in particular a button cell, comprising a housing (6) consisting of at least two parts (3, 4) respectively defining the poles of the battery, characterized in that the housing (6) comprises a contiguous zone (5). ) between the two parts (3, 4) defining an insulating joint, this contiguous area being formed of a layer of glue (2) in which is incorporated a spacer (1). 13. The battery of claim 12, wherein the two parts (3,4) respectively form a lid and a container of the housing (6). 14. The cell of claim 12 or 13, wherein the contiguous zone (5) is located in a cylindrical portion of the housing (6). 15. Battery according to claim 12 or 13, characterized in that the contiguous zone (5) is located in a frustoconical portion forming an upper portion of the housing (6). Battery according to any one of claims 12 to 15, characterized in that said adhesive layer (2) comprising the spacer (1) has a substantially constant thickness of between 30 μm and 200 μm, preferably between 50 μm. and 200 pm.