Patent Description:
Generally, a rechargeable battery is a battery that can be repeatedly charged and discharged.

In recent years, as a demand for wearable devices, such as headphones, earphones, smartwatches, and body-attached medical devices using wireless communication such as Bluetooth increases, a need for ultra-small rechargeable batteries installed in the wearable devices is increasing.

An electrode terminal disposed on an outer surface of the ultra-small rechargeable battery is in contact with a contact terminal of the wearable device to supply power to the wearable device.

However, since an oxide film may be naturally formed on the surface of the electrode terminal of the ultra-small rechargeable battery, there is a problem that contact resistance between the electrode terminal of the ultra-small rechargeable battery and the contact terminal of the wearable device is increased. There is a need to provide an ultra-small rechargeable battery to solve the problem.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

<CIT> discloses a rechargeable battery including a can, a lid and an electrode terminal having layers.

According to an aspect of one or more embodiments, a rechargeable battery is provided to suppress an increase of the contact resistance between the electrode terminal of the rechargeable battery and the contact terminal of the device.

A rechargeable battery according to one or more embodiments of the present invention includes: an electrode assembly including a first electrode, a second electrode, and a separator between the first electrode and the second electrode; a case connected to the first electrode and accommodating the electrode assembly, the case including an opening to receive the electrode assembly; a cap plate bonded to the case to cover an outer region of the opening and including a through-hole to expose a center region of the opening; a terminal plate bonded to and insulated from the cap plate, covering the through-hole, and connected to the second electrode; and a terminal plating layer coated on an upper surface of the terminal plate, and a thickness of a center portion of the terminal plating layer overlapping the through-hole is thicker than a thickness of an outer portion of the terminal plating layer overlapping the upper surface of the terminal plate.

A surface roughness of the center portion of the terminal plating layer may be less than a surface roughness of the outer portion of the terminal plating layer.

The terminal plating layer may have a ductility less than that of the terminal plate.

The center portion of the terminal plating layer may be protruded in an upper direction from the outer portion of the terminal plating layer.

The terminal plate may include aluminum, and the terminal plating layer may include nickel.

The case and the cap plate may include stainless steel.

The terminal plate may include: a terminal part on the cap plate; and a protruded part penetrating through the through-hole from the terminal part to be connected to the second electrode.

The terminal plating layer may be on an upper surface of the terminal part.

The center portion of the terminal plating layer may be protruded in an opposite direction to the protruded part.

The case and the cap plate may have a same polarity as the first electrode, and the terminal plate and the terminal plating layer may have a same polarity as the second electrode.

The rechargeable battery may further include a thermal-fusion layer between the cap plate and the terminal plate to insulate and bond the cap plate and the terminal plate.

The electrode assembly may further include: a first electrode tab extending from the first electrode to be bonded to the case; and a second electrode tab extending from the second electrode to be bonded to the terminal plate.

The center portion of the terminal plating layer may be a second electrode terminal of the rechargeable battery.

The second terminal of the rechargeable battery may be contactable to a terminal of an external device.

According to an aspect of one or more embodiments, a rechargeable battery is provided in which an increase of the contact resistance between the electrode terminal of the rechargeable battery and the contact terminal of a device is suppressed.

The present invention will be described more fully herein with reference to the accompanying drawings, in which some example embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

In addition, unless explicitly described to the contrary, it is to be understood that terms such as "comprises," "includes," or "have" used in the present specification specify the presence of stated features, numerals, steps, operations, components, parts, or a combination thereof, but do not preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or a combination thereof.

Also, in this specification, it is to be understood that when one component is referred to as being "connected" or "coupled" to another component, it may be connected or coupled directly to the other component or connected or coupled to another component with one or more other components intervening therebetween.

Singular forms are to include plural forms unless the context clearly indicates otherwise.

It is to be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. For example, a first element could be termed a "second" element, and, similarly, a second element could be termed a "first" element, without departing from the scope of example embodiments of the inventive concept. The terms of a singular form may include plural forms unless the context clearly indicates otherwise.

In addition, terms such as "below," "lower," "above," "upper," and the like are used to describe the relationship of the configurations shown in the drawings. However, the terms are used as a relative concept and are described with reference to the direction indicated in the drawings.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concept pertains. It is also to be understood that terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings in the context of the related art, and are expressly defined herein unless they are interpreted in an ideal or overly formal sense.

Next, a rechargeable battery according to an embodiment is described with reference to <FIG>.

The rechargeable battery according to an embodiment is an ultra-small rechargeable battery and may be a coin-type cell or a button-type cell, but is not limited thereto, and may be a cylindrical or pin-type cell.

Here, the coin-type cell or the button-type cell is a thin coin-type or button-shape cell and may refer to a cell having a ratio of a height to a diameter of <NUM> or less, however, it is not limited thereto. The coin cell or the button cell may be cylindrical, and a horizontal cross-section may be circular, but the present invention is not limited thereto, and a horizontal cross-section may be oval or polygonal. In this case, the diameter may refer to the maximum distance based on the horizontal direction of the battery, and the height may refer to the maximum distance (a distance from a flat bottom surface to a flat uppermost surface) based on the vertical direction of the battery.

<FIG> is a perspective view showing a rechargeable battery according to an embodiment; and <FIG> is a cross-sectional view taken along the line II-II of <FIG>.

Referring to <FIG> and <FIG>, a rechargeable battery <NUM> according to an embodiment includes an electrode assembly <NUM>, a case <NUM>, a cap plate <NUM>, a terminal plate <NUM>, a thermal-fusion layer <NUM>, and a terminal plating layer <NUM>.

The electrode assembly <NUM> is accommodated in the case <NUM>. A lower part of the electrode assembly <NUM> faces a lower part of the case <NUM>, and an upper part of the electrode assembly <NUM> faces the cap plate <NUM> and the terminal plate <NUM> covering an opening <NUM> of the case <NUM>. In an embodiment, the upper and lower parts of the electrode assembly <NUM> may have a planar shape parallel to each other, but are not limited thereto.

The electrode assembly <NUM> includes a first electrode <NUM>, a second electrode <NUM>, a separator <NUM>, a first electrode tab <NUM>, and a second electrode tab <NUM>.

The first electrode <NUM> and the second electrode <NUM> are separated from each other, and the separator <NUM> including an insulating material is disposed between the first electrode <NUM> and the second electrode <NUM>. In an embodiment, the first electrode <NUM> may be a cathode, and the second electrode <NUM> may be an anode, but the present invention is not limited thereto, and, in another embodiment, the first electrode <NUM> may be an anode and the second electrode <NUM> may be a cathode.

In an embodiment, the first electrode <NUM> has a band shape extending in a direction, and includes a cathode coated region that is an area where a cathode active material layer is coated to a current collector of a metal foil (for example, a Cu foil), and a cathode uncoated region that is an area where the active material is not coated. The cathode uncoated region may be disposed at an end in the extension direction of the first electrode <NUM>.

In an embodiment, the second electrode <NUM> has a band shape that is spaced apart from the first electrode <NUM> with the separator <NUM> interposed therebetween, and extends in a direction and includes an anode coated region that is an area where an anode active material layer is applied to the current collector of a metal foil (for example, an Al foil), and an anode uncoated region that is an area where the active material is not applied. The anode uncoated region may be disposed at an end in the extending direction of the second electrode <NUM>.

The separator <NUM> extends in a direction between the first electrode <NUM> and the second electrode <NUM> to prevent or substantially prevent a short circuit between the first electrode <NUM> and the second electrode <NUM>.

In an embodiment, the first electrode <NUM>, the separator <NUM>, and the second electrode <NUM> are sequentially stacked and wound in a jelly roll shape, but are not limited thereto, and may be formed in any of various known shapes. Each of the first electrode <NUM>, the second electrode <NUM>, and the separator <NUM> may include any of various known materials.

The first electrode tab <NUM> extends from the first electrode <NUM> of the electrode assembly <NUM> to the case <NUM>. In an embodiment, the first electrode tab <NUM> is combined with a lower part of the case <NUM> to connect the first electrode <NUM> and the case <NUM>. The first electrode tab <NUM> is in contact with the first electrode <NUM> and the case <NUM>. By the first electrode tab <NUM>, the case <NUM> has a same polarity (for example, a cathode polarity) as the first electrode <NUM>.

The second electrode tab <NUM> extends from the second electrode <NUM> of the electrode assembly <NUM> to the terminal plate <NUM>. In an embodiment, the second electrode tab <NUM> is combined with a protruded part <NUM> of the terminal plate <NUM> to connect the second electrode <NUM> and the terminal plate <NUM>. The second electrode tab <NUM> is in contact with the second electrode <NUM> and the terminal plate <NUM>. By the second electrode tab <NUM>, the terminal plate <NUM> has a same polarity as the second electrode <NUM> (for example, an anode polarity).

In an embodiment, a center pin penetrating the center of the electrode assembly <NUM> in a vertical direction is disposed in a center portion of the electrode assembly <NUM>, and the center pin may support the first electrode tab <NUM> and the second electrode tab <NUM>, but is not limited thereto.

The case <NUM> is connected to the first electrode <NUM> of the electrode assembly <NUM> and houses the electrode assembly <NUM>. The case <NUM> includes an opening <NUM> that exposes the top of the electrode assembly <NUM>. The lower part of the case <NUM> is connected to the first electrode <NUM> of the electrode assembly <NUM> by the first electrode tab <NUM>, and has the same polarity (for example, the cathode polarity) as the first electrode <NUM>. In an embodiment, the case <NUM> has a cylinder shape for accommodating the electrode assembly <NUM> in the form of the jelly roll, but is not limited thereto, and may have any of various known shapes. The case <NUM> can accommodate any of various known electrolyte solutions along with the electrode assembly <NUM>. The outer surface of the case <NUM> may be a cathode terminal of the rechargeable battery <NUM>. In this case, the outer surface of the terminal plate <NUM> coated with the terminal plating layer <NUM> may be an anode terminal of the rechargeable battery <NUM>. In an embodiment, a plating layer may be coated on the outer surface of the case <NUM>, but is not limited thereto, and any of various known coating layers may be coated on the outer surface of the case <NUM>.

The opening <NUM> of the case <NUM> is covered by the cap plate <NUM> and the terminal plate <NUM>.

The cap plate <NUM> is combined with the case <NUM> to cover an outer area of the opening <NUM>. The cap plate <NUM> includes a through-hole <NUM> that exposes a central area of the opening <NUM>. In an embodiment, the cap plate <NUM> is directly coupled to a side wall of the case <NUM> by a welding process to cover the outer area of the opening <NUM>. Here, the outer area of the opening <NUM> is defined in the vicinity of the side wall of the case <NUM>, which surrounds. the center area of the opening <NUM>. In an embodiment, the cap plate <NUM> has a ring shape by the through-hole <NUM> formed in the center, but is not limited thereto. The cap plate <NUM> is combined with the case <NUM>, and has the same polarity (for example, the cathode polarity) as first electrode <NUM>. In an embodiment, the cap plate <NUM> includes stainless steel, but is not limited thereto, and may include any of metals, such as aluminum, nickel, and copper.

In an embodiment, a plating layer may be coated on the outer surface of the cap plate <NUM>, but the present invention is not limited thereto, and any of various known coating layers may be coated on the outer surface of the cap plate <NUM>.

The terminal plate <NUM> is insulated and combined to the cap plate <NUM> to cover the through-hole <NUM> of the cap plate <NUM>. The terminal plate <NUM> is disposed on the cap plate <NUM>. The terminal plate <NUM> covers the central area of the opening <NUM> of the case <NUM> exposed by the through-hole <NUM> of the cap plate <NUM>. Since the terminal plate <NUM> covers the central area of the opening <NUM> and the cap plate <NUM> covers the outer area of the opening <NUM>, the opening <NUM> of the case <NUM> is completely covered by the terminal plate <NUM> and the cap plate <NUM>. The terminal plate <NUM> is connected to the second electrode tab <NUM> of the electrode assembly <NUM> to be connected to the second electrode <NUM> of the electrode assembly <NUM>. The terminal plate <NUM> has the same polarity (for example, the anode polarity) as the second electrode <NUM>.

The terminal plate <NUM> includes a terminal part <NUM> and the protruded part <NUM>.

The terminal part <NUM> is disposed on the cap plate <NUM> and overlaps the cap plate <NUM>. The terminal part <NUM> has a wider area than the protruded part <NUM>. For example, the terminal part <NUM> may have a larger diameter than the protruded part <NUM>. A lower surface of the terminal part <NUM> is in contact with the thermal-fusion layer <NUM>, and the terminal part <NUM> is insulated and combined to the cap plate <NUM> by the thermal-fusion layer <NUM>.

The protruded part <NUM> is protruded from the terminal part <NUM> corresponding to the through-hole <NUM> of the cap plate <NUM>, and penetrates the through-hole <NUM>. A lower surface of the protruded part <NUM> is in contact with the second electrode tab <NUM>. As the protruded part <NUM> is combined with the second electrode tab <NUM>, the terminal plate <NUM> has the same polarity as the second electrode <NUM>.

In an embodiment, the terminal plate <NUM> includes aluminum, but is not limited thereto, and may include any of metals, such as stainless steel, nickel, and copper.

The thermal-fusion layer <NUM> is disposed between the cap plate <NUM> and the terminal part <NUM> of the terminal plate <NUM>, and insulates and bonds between the cap plate <NUM> and the terminal plate <NUM>. The thermal-fusion layer <NUM> includes an insulating material, and insulates between the cap plate <NUM> and the terminal plate <NUM>. In an embodiment, the thermal-fusion layer <NUM> is thermally fused between the cap plate <NUM> and the terminal part <NUM> of the terminal plate <NUM> by using heat or a laser beam. The thermal-fusion layer <NUM> may include any of various known materials for insulating and bonding between the cap plate <NUM> and the terminal plate <NUM>. By bonding the thermal-fusion layer <NUM> between the cap plate <NUM> and the terminal plate <NUM>, the opening <NUM> of the case <NUM> in which the electrode assembly <NUM> is accommodated is completely sealed by the cap plate <NUM>, the terminal plate <NUM>, and the thermal-fusion layer <NUM>.

The terminal plating layer <NUM> is coated on an upper surface of the terminal plate <NUM>. In an embodiment, the terminal plating layer <NUM> is coated only on the upper surface of the terminal part <NUM> of the terminal plate <NUM>, but is not limited thereto, and, in another embodiment, may be coated on the entire surface of the terminal plate <NUM>.

The terminal plate <NUM> coated with the terminal plating layer <NUM> forms an anode terminal having the same polarity as the second electrode <NUM> of the electrode assembly <NUM> of the rechargeable battery <NUM>, but is not limited thereto.

The terminal plating layer <NUM> includes a center portion <NUM> and an outer portion <NUM>, and the center portion <NUM> of the terminal plating layer <NUM> is protruded upward from the outer portion <NUM>. In an embodiment, the terminal plating layer <NUM> may be plated on the upper surface of the terminal plate <NUM> in the form of a plate and formed in a form including a center portion <NUM> and an outer portion <NUM> by a forging process, but is not limited thereto.

For example, the terminal plating layer <NUM> is plated on the upper surface of the plate-shaped terminal plate <NUM> in the plate form, and the outer portion of the plate-shaped terminal plate <NUM> plated with the plate-shaped terminal plating layer <NUM> is forging-processed, thereby the terminal plate <NUM> including the terminal part <NUM> and the protruded part <NUM> and the terminal plating layer <NUM> including the center portion <NUM> and the outer portion <NUM> may be concurrently (e.g., simultaneously) formed.

<FIG> is a cross-sectional view showing a region "A" of <FIG>.

Referring to <FIG>, the center portion <NUM> of the terminal plating layer <NUM> overlaps a portion corresponding to the through-hole <NUM> of the cap plate <NUM> in a direction perpendicular to the through-hole <NUM>, and the outer portion <NUM> of the terminal plating layer <NUM> overlaps a portion corresponding to a surface of the cap plate <NUM> in the direction perpendicular to the surface of the cap plate <NUM>.

In an embodiment, a first thickness T1 of the center portion <NUM> of the terminal plating layer <NUM> is thicker than a second thickness T2 of the outer portion <NUM>. The center portion <NUM> of the terminal plating layer <NUM> is protruded upward from the surface of the terminal plate <NUM> from the outer portion <NUM>. The center portion <NUM> of the terminal plating layer <NUM> is protruded in an opposite direction to the protruded part <NUM> of the terminal plate <NUM>.

The first thickness T1 of the center portion <NUM> of the terminal plating layer <NUM> is thicker than the second thickness T2 of the outer portion <NUM> and the center portion <NUM> is protruded upward from the surface of the terminal plate <NUM> from the outer portion <NUM>. Here, the center portion <NUM> of the terminal plating layer <NUM> is the electrode terminal of the rechargeable battery <NUM>.

The rechargeable battery <NUM> may suppress an increase of the contact resistance between the center portion <NUM> of the terminal plating layer <NUM> and a contact terminal of a device. The electrode terminal of the rechargeable battery <NUM> may be in contact with a contact terminal of a device by a stronger pressure than the outer portion <NUM>. Then, the contact area between the center portion <NUM> of the terminal plating layer <NUM> and the contact terminal of the device is increased, so that an increase of the contact resistance between the center portion <NUM> of the terminal plating layer <NUM> that is an electrode terminal of the rechargeable battery <NUM> and the contact terminal of the device may be suppressed.

In an embodiment, a surface roughness of the center portion <NUM> of the terminal plating layer <NUM> is less than a surface roughness of the outer portion <NUM>. In an embodiment, the surface of the center portion <NUM> of the terminal plating layer <NUM> is flatter than the surface of the outer portion <NUM>.

As the surface roughness of the center portion <NUM> of the terminal plating layer <NUM> is less than the surface roughness of the outer portion <NUM>, the center portion <NUM> of the terminal plating layer <NUM> that is the electrode terminal of the rechargeable battery <NUM> may be in contact with a contact terminal of a device with a greater area than the outer portion <NUM> such that the contact area between the center portion <NUM> of the terminal plating layer <NUM> and the contact terminal of the device is increased, and thereby an increase of the contact resistance between the center portion <NUM> of the terminal plating layer <NUM> that is an electrode terminal of the rechargeable battery <NUM> and the contact terminal of the device may be suppressed.

In an embodiment, the terminal plating layer <NUM> has less ductility than the terminal plate <NUM>. In an embodiment, the terminal plating layer <NUM> is more rigid than the terminal plate <NUM>.

As the terminal plating layer <NUM> has less ductility than the terminal plate <NUM>, the rechargeable battery <NUM> may suppress an increase of the contact resistance between the center portion <NUM> of the terminal plating layer <NUM> and a contact terminal of a device.

The terminal plating layer <NUM> that is the electrode terminal of the rechargeable battery <NUM> may be suppressed from being deformed by pressure due to the contact with a contact terminal of a device such that a reduction of the contact area between the terminal plating layer <NUM> and the contact terminal of a e device due to deformation of the terminal plating layer <NUM> may be suppressed. Thus, the rechargeable battery <NUM> may suppress an increase of the contact resistance between the terminal plating layer <NUM> that is the electrode terminal of the rechargeable battery <NUM> and the contact terminal of the device.

In an embodiment, the terminal plating layer <NUM> includes nickel (Ni), and the terminal plate <NUM> includes aluminum (Al).

In an embodiment, as the terminal plating layer <NUM> includes nickel, which has higher corrosion resistance compared to aluminum contained in the terminal plate <NUM>, since the formation of an oxide layer on the surface of the terminal plating layer <NUM> that is in contact with a contact terminal of a device may be suppressed, an increase in the contact resistance between the terminal plating layer <NUM>, which is an electrode terminal of the rechargeable battery <NUM> and the contact terminal of the device, may be suppressed.

As described above, in the rechargeable battery <NUM> according to an embodiment, the first thickness T1 of the center portion <NUM> of the terminal plating layer <NUM> is thicker than the second thickness T2 of the outer portion <NUM>, the surface roughness of the center portion <NUM> is less than the surface roughness of the outer portion <NUM>, and the terminal plating layer <NUM> contains nickel (Ni) while having less ductility than the terminal plate <NUM>. The rechargeable battery <NUM> may suppress an increase of the contact resistance between the center portion <NUM> of the terminal plating layer <NUM> and a contact terminal of a device.

, The center portion <NUM> of the terminal plating layer <NUM> as the electrode terminal of the rechargeable battery <NUM> may be in contact with a contact terminal of a device in a large area with a strong pressure, and an increase of the contact area between the terminal plating layer <NUM> and the contact terminal of the device and concurrently (e.g., simultaneously) deformation of the terminal plating layer <NUM> by pressure due to the contact with the contact terminal of the device may be suppressed and the formation of an oxide layer on the surface of the terminal plating layer <NUM> may be suppressed, and thereby an increase of the contact resistance between the terminal plating layer <NUM> as an electrode terminal of the rechargeable battery <NUM> and the contact terminal of the device may be suppressed.

That is, the rechargeable battery <NUM>, in which the contact resistance between the electrode terminal of the rechargeable battery <NUM> and the contact terminal of the device is suppressed, is provided.

Claim 1:
A rechargeable battery comprising:
an electrode assembly (<NUM>) comprising a first electrode (<NUM>), a second electrode (<NUM>), and a separator (<NUM>) between the first electrode (<NUM>) and the second electrode (<NUM>);
a case (<NUM>) connected to the first electrode (<NUM>) and accommodating the electrode assembly, the case comprising an opening (<NUM>) to receive the electrode assembly;
a cap plate (<NUM>) bonded to the case (<NUM>) to cover an outer region of the opening (<NUM>) and comprising a through-hole (<NUM>) to expose a center region of the opening (<NUM>);
a terminal plate (<NUM>) bonded to and insulated from the cap plate (<NUM>), covering the through-hole (<NUM>), and connected to the second electrode (<NUM>); and
a terminal plating layer (<NUM>) coated on an upper surface of the terminal plate (<NUM>),
wherein a thickness of a center portion (<NUM>) of the terminal plating layer (<NUM>) overlapping the through-hole (<NUM>) is thicker than a thickness of an outer portion of the terminal plating layer (<NUM>) overlapping the upper surface of the terminal plate (<NUM>).