JP2023050693A - Tab lead and nonaqueous electrolyte device - Google Patents

Abstract

To increase the durability of a lead material to achieve the long life and high reliability of a tab lead.SOLUTION: Provided is a tab lead that is provided in a laminated nonaqueous electrolyte device in which at least an electrode and an electrolytic solution or a solid electrolyte are sealed inside a laminate material. The tab lead includes: a lead material which is formed of a metallic material and has both ends provided as an electrode connection to be connected to the electrode and a terminal connection to be connected external equipment, respectively; nickel plating covering a surface of the lead material; a coat covering a surface of the nickel plating; and a pair of seal portions brought into close contact with the coat from both sides. The nickel plating has an arithmetic average roughness measured by an atomic force microscope of 5.0 nm or more, and a half band width measured by an X-ray diffraction method of 0.5 degree or less.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a technical field of a tab lead having a lead material connected to an electrode and an external device, and a non-aqueous electrolyte device having the same.

Non-aqueous electrolyte devices include, for example, lithium ion batteries and lithium ion capacitors. Lithium-ion batteries have the function of charging and discharging by moving lithium ions between the positive and negative electrodes, and lithium-ion capacitors use an electric double-layer positive electrode and a carbon-based material that can adsorb lithium ions. It has a function of performing charging and discharging in a structure in which a negative electrode is provided.

Such a non-aqueous electrolyte device includes, for example, a laminated type used as a vehicle battery or storage battery, in which an electrode and an electrolytic solution or a solid electrolyte are sealed inside a bag-shaped laminated material. In a laminated non-aqueous electrolyte device, power is taken out by tab leads.

The tab lead has a metal lead material that functions as a terminal member for extracting power. One end of the lead material is connected to an electrode arranged inside the laminate material, and the other end is exposed outside the laminate material and connected to a bus bar or the like, which is a connection terminal of an external device.

In such a tab lead, the surface of the lead material is nickel-plated and a film (surface treatment layer) is applied to the nickel-plated surface to protect the lead material and prevent oxidation of the lead material. Etching by an electrolytic solution or the like is prevented (see, for example, Patent Documents 1 and 2).

JP 2014-186914 A JP 2014-220129 A

By the way, in the tab lead, as described above, the nickel plating protects the lead material, but depending on the amount of impurities contained in the nickel plating, the corrosion resistance of the nickel plating to the electrolytic solution is lowered, and the nickel plating is not compatible with the electrolytic solution. The lead material is etched by hydrofluoric acid generated by the reaction of moisture, and the lead material is oxidized and etched, resulting in insufficient protection of the lead material.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to improve the durability of the lead material and to extend the life and reliability of the tab lead.

A tab lead according to the present invention is a tab lead provided in a laminate type non-aqueous electrolyte device in which at least an electrode and an electrolytic solution or a solid electrolyte are sealed inside a laminate material, the tab lead being formed of a metal material and having both ends as described above. A lead material provided as an electrode connection part connected to an electrode and a terminal connection part connected to an external device, nickel plating covering the surface of the lead material, a coating covering the surface of the nickel plating, and the coating and a pair of sealing portions that are closely attached from both sides, and the nickel plating has an arithmetic mean roughness of 5.0 nm or more measured by an atomic force microscope and a half width of 0.5 degrees measured by an X-ray diffraction method. It has been done below.

This reduces the amount of impurities contained in the nickel plating and increases the corrosion resistance of the nickel plating to the electrolyte.

A non-aqueous electrolyte device according to the present invention is a laminate-type non-aqueous electrolyte device in which at least an electrode and an electrolytic solution or a solid electrolyte are sealed inside a laminate material and a tab lead is provided, wherein the tab lead is made of a metal material. A lead material provided as an electrode connection part formed and having both ends connected to the electrodes and a terminal connection part connected to an external device, a nickel plating covering the surface of the lead material, and a surface of the nickel plating. A covering coating and a pair of sealing portions that are in close contact with the coating from both sides are provided, and the nickel plating has an arithmetic average roughness of 5.0 nm or more as measured by an atomic force microscope and is measured by an X-ray diffraction method. The half width is set to 0.5 degrees or less.

As a result, in the tab lead, the amount of impurities contained in the nickel plating is reduced, and the corrosion resistance of the nickel plating to the electrolytic solution is enhanced.

According to the tab lead and the non-aqueous electrolyte device of the present invention, the amount of impurities contained in the nickel plating is reduced and the corrosion resistance of the nickel plating to the electrolytic solution is increased, so that oxidation of the lead material can be prevented and electrolysis can be performed. Etching by hydrofluoric acid generated by the reaction between liquid and water can be prevented, the durability of the lead material can be improved, and the life and reliability of the tab lead can be increased.

The embodiment of the present invention is shown together with FIGS. 2 to 6, and this figure is a front view of a non-aqueous electrolyte device. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1; FIG. 4 is a perspective view of a tab lead; FIG. 3 is a cross-sectional view showing a layer structure of a terminal portion; It is a graph showing the measurement result about a terminal part. It is a graph chart showing another measurement result about a terminal area.

EMBODIMENT OF THE INVENTION Below, the form for implementing the tab lead and nonaqueous electrolyte device of this invention is demonstrated with reference to an accompanying drawing.

<Schematic configuration of non-aqueous electrolyte device>
First, as an example of a laminate-type nonaqueous electrolyte device, a schematic configuration of a lithium ion battery will be described (see FIGS. 1 and 2). The scope of application of the nonaqueous electrolyte device of the present invention is not limited to lithium ion batteries, and the present invention can also be applied to other nonaqueous electrolyte devices such as laminated lithium ion capacitors.

A non-aqueous electrolyte device has a laminate material in which an electrolyte or the like is enclosed and a tab lead partially protruding from the laminate material. shall be referred to as the upper direction, and the front, back, up, down, left, and right directions shall be indicated. However, the front, rear, up, down, left, and right directions shown below are for convenience of explanation, and the implementation of the present invention is not limited to these directions.

The non-aqueous electrolyte device 100 has a bag-shaped laminate material 101, various parts sealed inside the laminate material 101, and tab leads 1, 1 partially protruding from the laminate material 101 (see FIG. 1). ).

The laminate material 101 has a bag shape with an upper end formed as a sealing portion 102 . The laminate material 101 has, for example, a three-layer structure, in which an outer layer 101a and an inner layer 101b each made of a resin material are laminated on both sides of a metal layer 101c (see FIG. 2). For example, polyethylene terephthalate is used as the outer layer 101a, polypropylene or polyethylene is used as the inner layer 101b, and aluminum or stainless steel is used as the metal layer 101c.

Inside the laminate material 101, an electrolytic solution 103 is enclosed, and a positive electrode 104, a negative electrode 105, and a separator 106 are arranged. The positive electrode 104 and the negative electrode 105 are immersed in the electrolytic solution 103 , and the space in which the positive electrode 104 is arranged and the space in which the negative electrode 105 is arranged are separated by the separator 106 . Aluminum, for example, is used for the positive electrode 104, and nickel, copper, or an alloy thereof is used for the negative electrode 105, for example. A solid electrolyte may be used instead of the electrolytic solution 103 .

<Structure of Tab Lead>
Next, the configuration of the tab lead 1 will be described (see FIGS. 2 to 4). One pair of tab leads 1 connected to the positive electrode 104 functions as a positive electrode in the non-aqueous electrolyte device 100, and the other tab lead 1 connected to the negative electrode 105 functions as the positive electrode in the non-aqueous electrolyte device 100. It functions as a negative electrode.

The tab lead 1 has a thin plate-like terminal portion 2 and a pair of sealing portions 3, 3 which are in close contact with the terminal portion 2 from both sides (see FIGS. 2 and 3). A portion of the outer peripheral surface of the tab lead 1 is brought into close contact with the sealing portion 102 , and the upper end portion of the tab lead 1 protrudes upward from the laminate material 101 .

The terminal portion 2 is formed in a thin plate shape with a thickness of, for example, 50 μm to 3000 μm. A lower end portion of the terminal portion 2 is provided as an electrode connection portion 2a, and is connected to the positive electrode 104 or the negative electrode 105 by welding or the like, for example. An upper end portion of the terminal portion 2 is provided as a terminal connection portion 2b exposed to the outside from the laminate material 101, and is connected to a connection terminal (bus bar) (not shown) of an external device by welding or the like.

The seal portions 3, 3 are in close contact with the terminal portion 2 from both sides and also in close contact with the inner surface of the sealing portion 102 of the laminate material 101 to seal the laminate material 101, and the electrolytic solution enclosed inside the laminate material 101. It has a function of preventing liquid leakage such as 103 . Moreover, the seal portions 3, 3 are interposed between the terminal portion 2 and the laminate material 101, and also have a function of ensuring insulation between the terminal portion 2 and the laminate material 101. FIG.

The seal portions 3, 3 are formed in a shape extending in a direction orthogonal to the longitudinal direction of the terminal portion 2, and are in close contact with both sides of the terminal portion 2 in the thickness direction. The seal portion 3 has a thickness of, for example, 75 μm to 300 μm, and the central portion in the longitudinal direction is in close contact with the terminal portion 2 . The seal portion 3 may be made of a single layer or may be made of multiple layers. The sealing portion 3 is adhered to the terminal portion 2 and the sealing portion 102 of the laminate material 101 by, for example, thermocompression bonding.

The terminal portion 2 is composed of a lead material 4 provided as a base material, a nickel plating 5 covering the surface of the lead material 4, and a coating 6 covering the surface of the nickel plating 5 (see FIG. 4).

The lead material 4 is made of a metal material such as aluminum or copper. The lead material 4 is thin and formed in a rectangular shape, for example.

The nickel plating 5 has excellent corrosion resistance to the electrolytic solution 103, has a function of protecting the lead material 4, and has a thickness of, for example, 1 μm or more. By protecting the lead material 4, the nickel plating 5 has the function of preventing the lead material 4 from being oxidized and also preventing the lead material 4 from being etched by hydrofluoric acid generated by the reaction between the electrolytic solution 103 and moisture. As the nickel plating 5, a matte type or a semi-bright type is used.

By using a non-glossy type or a semi-glossy type as the nickel plating 5, the content of impurities in the nickel plating 5 is reduced, and high corrosion resistance to the electrolytic solution 103 is ensured. Therefore, it is desirable that the nickel plating 5 be made of matte or near-matte material containing as few impurities as possible.

In this way, the nickel plating 5 is formed as a matte or semi-gloss type with a low impurity content, and has an arithmetic mean roughness of 5 as measured by an atomic force microscope (AFM). 0 nm or more, and the half-value width measured by the X-ray diffraction method is 0.5 degrees or less. The degree of unevenness of the surface of the nickel plating 5 is defined by the arithmetic mean roughness, and the crystallinity of the nickel plating 5 is defined by the half width.

An atomic force microscope is a type of scanning probe microscope, and is a microscope that obtains an image by detecting forces acting between atoms on the surface of a sample and a probe tip. For example, a 2 μm square range is set as the measurement range of the arithmetic mean roughness by the atomic force microscope. The smaller the value of the arithmetic mean roughness, the higher the degree of gloss.

The X-ray diffraction method (θ/2θ) is a method of examining the crystal structure of a substance by utilizing the diffraction of X-rays in a crystal lattice. It is possible to measure the content of impurities in the nickel plating 5 by examining the crystal structure of the nickel plating 5 by the X-ray diffraction method, and the smaller the half-value width, the higher the content of impurities in the nickel plating 5. few.

The film 6 is formed by filling the irregularities of the nickel plating 5 with a material having high corrosion resistance to the electrolytic solution 103, such as a chromium salt or a zirconium salt. The coating 6 has a thickness of 20 nm or more, for example.

<Results of measurements on terminals>
Measurement results regarding the terminal portion will be described below (see FIGS. 5 and 6).

FIG. 5 shows the results of measuring the residual rate of nickel plating for three types of terminal portions with different degrees of gloss. In addition, the terminal portions (samples) used in the measurement shown in FIG. 5 are all nickel-plated on the surface of the lead material, but are not coated.

Data A is the measurement result of the terminal portion with matte nickel plating, Data B is the terminal portion with semi-bright nickel plating, and Data C is the terminal portion with bright nickel plating. The etching rate, arithmetic mean roughness and half width of data A, data B and data C are shown in the table. Each value of data A, data B, and data C is a value measured for each predetermined surface of 2 μm square.

The horizontal axis indicates the time during which the terminal portion was immersed in the electrolytic solution. The vertical axis indicates the residual rate of nickel plating, and the residual rate of nickel plating is 100% when the terminal portion is immersed in the electrolytic solution for 0 hours. Water is added to the electrolytic solution, and as the amount of water added to the electrolytic solution increases, the amount of hydrofluoric acid generated increases and the nickel plating is easily etched. The amount of water added to the electrolytic solution is 10000 ppm. The amount of water added to the electrolytic solution in this measurement is an example, and the amount of water added to the electrolytic solution may be, for example, 1000 ppm. In this case, the maximum test time is 720 ppm. Timed.

In this measurement, the terminals formed with matte nickel plating and the terminals formed with semi-bright nickel plating had a higher residual rate of nickel plating than the terminals formed with bright nickel plating. In particular, it was found that the terminals formed with matte nickel plating had a much higher rate of residual nickel plating than the terminals formed with bright nickel plating.

Therefore, when the nickel plating is matte or semi-gloss, the nickel plating has high corrosion resistance to the electrolytic solution, and it is possible to prevent the lead material from being oxidized. It can be seen that etching by hydrofluoric acid can be prevented. In particular, when the nickel plating is made matte, the nickel plating has an extremely high corrosion resistance to the electrolytic solution, which prevents oxidation of the lead material and hydrofluoric acid generated by the reaction between the electrolytic solution of the lead material and moisture. It can be seen that the effect of preventing the etching by is further enhanced.

FIG. 6 shows the results of measuring the remaining thickness of the nickel plating with respect to the matte terminal portions with and without coating. In addition, the terminal portions (samples) used in the measurement shown in FIG. 6 all have nickel plating on the surface of the lead material.

Data D, Data E, and Data F are the measurement results for the terminals on which matte nickel plating is formed. Data F is the measurement result of the terminal portion having the zirconium salt film formed thereon.

The horizontal axis indicates the time during which the terminal portion was immersed in the electrolytic solution. The vertical axis indicates the remaining thickness of the nickel plating, and the thickness of the nickel plating of each terminal portion is 2.0 μm before the terminal portion is immersed in the electrolytic solution. Water is added to the electrolytic solution, and as the amount of water added to the electrolytic solution increases, the amount of hydrofluoric acid generated increases and the nickel plating is easily etched. The amount of water added to the electrolytic solution is 10000 ppm. The amount of water added to the electrolytic solution in this measurement is an example, and the amount of water added to the electrolytic solution may be, for example, 1000 ppm. In this case, the maximum test time is 720 ppm. Timed.

In this measurement, the terminals with the film formed have a thicker remaining nickel plating than the terminals without the film. A result was obtained that the thickness of the remaining nickel plating was extremely thick with respect to the terminal portion where the nickel plating was not applied.

Therefore, the formation of the film makes it difficult for the nickel plating to be etched by hydrofluoric acid generated by the reaction between the electrolyte and water, thereby preventing oxidation of the nickel plating and the lead material. It can be seen that etching by generated hydrofluoric acid can be prevented. In particular, the zirconium salt film has a high effect of preventing etching by hydrofluoric acid generated by the reaction between the electrolytic solution of nickel plating and moisture. It can be seen that the effect of preventing etching due to the hydrofluoric acid generated by is further enhanced.

<Summary>
As described above, in the tab lead 1 and the non-aqueous electrolyte device 100 having the same, the lead material 4 having both ends as the electrode connection part 2a and the terminal connection part 2b, respectively, and the surface of the lead material 4 A nickel plating 5 covering the surface of the nickel plating 5, a coating 6 covering the surface of the nickel plating 5, and a pair of seal portions 3 that are in close contact with the coating 6 from both sides, and the nickel plating 5 has an arithmetic mean roughness measured by an atomic force microscope. is set to 5.0 nm or more, and the half width measured by the X-ray diffraction method is set to 0.5 degrees or less.

Therefore, the amount of impurities contained in the nickel plating 5 is reduced and the corrosion resistance of the nickel plating 5 to the electrolytic solution 103 is increased, so that the lead material 4 can be prevented from being oxidized and etched by the electrolytic solution 103. As a result, the durability of the lead material 4 can be increased, and the life and reliability of the tab lead 1 can be increased.

In addition, since oxidation of the lead material 4 is prevented and an oxide film is less likely to be formed on the surface of the lead material 4, the welding strength is reduced when the terminal portion 2 is connected (fixed) to an electrode or a connection terminal of an external device by welding. It is possible to improve the fixing strength between the terminal portion 2 and the electrodes and the connection terminals without causing deterioration or the like.

Furthermore, since the lead material 4 is made of aluminum or copper, the lead material 4 is made of a metal material having high conductivity and high strength. It is possible to ensure a good conduction state and to ensure high durability.

Furthermore, since the coating 6 is formed of a chromium salt or a zirconium salt, the coating 6 protects the nickel plating 5 from the electrolytic solution 103, so that the coating 6 is free from hydrofluoric acid generated by the reaction between the electrolytic solution 103 and moisture. The high durability of the lead material 4 can be ensured because the lead material 4 is difficult to be etched.

In addition, since the thickness of the coating 6 is set to 20 nm or more, a sufficient thickness of the coating 6 for protecting the nickel plating 5 is secured, and the nickel plating 5 is generated by the reaction between the electrolytic solution 103 and moisture. Etching by hydrofluoric acid is made more difficult, and higher durability of the lead material 4 can be ensured.

In addition, since the nickel plating 5 has a thickness of 1 μm or more, it is difficult for holes to be formed in the nickel plating 5 when the nickel plating 5 is produced as electrolytic plating. The lead material 4 is hardly etched by hydrofluoric acid generated by the reaction of (1), so that a higher durability can be secured for the lead material 4 .

<Others>
The above example shows an example in which the tab leads 1, 1 connected to the positive electrode 104 or the negative electrode 105 both protrude in the same direction (upward) from the laminate material 101. Tab leads 1, 1 connected to the negative electrode 105 may protrude from the laminate material 101 in opposite directions.

100 Non-aqueous electrolyte device 101 Laminate material 2 Terminal part 2a Electrode connection part 2b Terminal connection part 4 Lead material 5 Nickel plating 6 Coating

Claims (6)

A tab lead provided in a laminate type non-aqueous electrolyte device in which at least an electrode and an electrolytic solution or a solid electrolyte are sealed inside a laminate material,
a lead material provided as an electrode connection portion formed of a metal material and having both ends connected to the electrodes and a terminal connection portion connected to an external device;
Nickel plating covering the surface of the lead material;
a coating covering the surface of the nickel plating;
A pair of seal portions that are in close contact with the coating from both sides,
The nickel plating has an arithmetic average roughness of 5.0 nm or more as measured by an atomic force microscope and a half width of 0.5 degrees or less as measured by an X-ray diffraction method. The tab lead according to claim 1, wherein the lead material is made of aluminum or copper. 3. Tab lead according to claim 1 or 2, wherein the coating is formed by a chromium salt or a zirconium salt. 4. The tab lead according to claim 1, 2 or 3, wherein the coating has a thickness of 20 nm or more. 5. The tab lead according to claim 1, 2, 3 or 4, wherein the nickel plating has a thickness of 1 [mu]m or more. A laminate type non-aqueous electrolyte device in which at least an electrode and an electrolytic solution or a solid electrolyte are sealed inside a laminate material and tab leads are provided,
The tab lead is
a lead material provided as an electrode connection portion formed of a metal material and having both ends connected to the electrodes and a terminal connection portion connected to an external device;
Nickel plating covering the surface of the lead material;
a coating covering the surface of the nickel plating;
A pair of seal portions that are in close contact with the coating from both sides,
The nickel plating has an arithmetic average roughness of 5.0 nm or more as measured by an atomic force microscope and a half width of 0.5 degrees or less as measured by an X-ray diffraction method.

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