Patent Description:
The present disclosure relates to an electrode assembly.

<CIT> discloses a so-called laminated electrode assembly in which a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated with a separator interposed therebetween. <CIT> and <CIT> disclose background art.

In the electrode assembly described in <CIT>, it is concerned that a positional displacement of the electrode with respect to the separator may occur when the electrode assembly is transported or when the electrode assembly is inserted into the cell case.

An object of the present disclosure is to provide an electrode assembly capable of preventing a positional displacement of an electrode with respect to a separator.

According to an aspect of the present disclosure, there is provided an electrode assembly as defined in the claims.

Embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding members are denoted by the same reference numerals.

<FIG> is a perspective view schematically illustrating a power storage cell <NUM> according to an embodiment of the present disclosure. <FIG> is a cross-sectional view of the power storage cell <NUM> illustrated in <FIG>.

As illustrated in <FIG> and <FIG>, the power storage cell <NUM> includes an electrode assembly <NUM>, a cell case <NUM>, an electrolytic solution (not illustrated), a pair of external terminals <NUM>, a pair of connecting members <NUM>, and an insulating member <NUM>.

<FIG> is a cross-sectional view of the electrode assembly <NUM>. As illustrated in <FIG>, the electrode assembly <NUM> includes a plurality of electrodes <NUM> and <NUM>, a separator <NUM>, and an insulating film <NUM> (see <FIG>).

As illustrated in <FIG>, the plurality of electrodes <NUM> and <NUM> are arranged side by side in one direction (the lateral direction in <FIG>). The plurality of electrodes <NUM> and <NUM> include a plurality of positive electrodes <NUM> and a plurality of negative electrodes <NUM>.

Each positive electrode <NUM> is formed in a rectangular shape elongated in a width direction (a direction orthogonal to both the one direction and the vertical direction). Each positive electrode <NUM> includes a positive electrode collector foil <NUM> and a positive electrode active material layer <NUM> provided on both surfaces of the positive electrode collector foil <NUM>. As illustrated in <FIG> and <FIG>, the positive electrode collector foil <NUM> includes a positive electrode tab 112p on which the positive electrode active material layer <NUM> is not provided. The positive electrode tab 112p protrudes toward one side of the width direction (a direction orthogonal to the paper surface of <FIG>).

Each negative electrode <NUM> is formed in a rectangular shape elongated in the width direction. Each negative electrode <NUM> includes a negative electrode collector foil <NUM> and a negative electrode active material layer <NUM> provided on both surfaces of the negative electrode collector foil <NUM>. As illustrated in <FIG> and <FIG>, the negative electrode collector foil <NUM> includes a negative electrode tab 122n on which the negative electrode active material layer <NUM> is not provided. The negative electrode tab 122n protrudes toward the other side of the width direction.

The separator <NUM> insulates the positive electrode <NUM> and the negative electrode <NUM> from each other. The separator <NUM> is made of an insulating material, and has minute voids that allow ions to pass through. As illustrated in <FIG>, the separator <NUM> is formed in a zigzag shape.

<FIG> is a plan view of the separator before being formed in a zigzag shape. As illustrated in <FIG>, the separator <NUM> has a rectangular shape before being formed in a zigzag shape. The separator <NUM> is formed in a zigzag shape and is arranged between the electrodes <NUM> and <NUM>. The separator <NUM> includes a plurality of intervening portions 132a, a plurality of upper folded portions 132b, a plurality of lower folded portions 132c, and an outermost covering portion 132d.

Each intervening portion 132a is interposed between a pair of electrodes <NUM> and <NUM> adjacent to each other in the one direction. In other words, each intervening portion 132a functions to insulate the positive electrode <NUM> and the negative electrode <NUM> from each other. Each intervening portion 132a is formed in a rectangular shape.

Each upper folded portion 132b connects an upper end of one intervening portion 132a of the plurality of intervening portions 132a and an upper end of another intervening portion 132a of the plurality of intervening portions 132a which is adjacent to the one intervening portion 132a on one side of the one direction. In the present embodiment, the upper folded portion 132b is disposed above the positive electrode <NUM>.

Each lower folded portion 132c connects a lower end of one intervening portion 132a of the plurality of intervening portions 132a and a lower end of another intervening portion 132a of the plurality of intervening portions 132a which is adjacent to the one intervening portion 132a on the other side of the one direction. In the present embodiment, the lower folded portion 132c is disposed below the negative electrode <NUM>. In other words, the negative electrode <NUM> is disposed above the lower folded portion 132c.

Each of the lower folded portions 132c is connected to a lower end of the negative electrode <NUM>, more specifically, a lower end of the negative electrode collector foil <NUM>. Specifically, as indicated by arrows in <FIG>, heat is applied from the outside of the lower folded portion 132c to the lower folded portion 132c by laser irradiation or the like. Thereby, the lower folded portion 132c is connected (welded) to the lower end of the negative electrode collector foil <NUM>.

The outermost covering portion 132d collectively covers each upper folded portion 132b and each lower folded portion 132c. More specifically, the outermost covering portion 132d collectively covers all of the electrodes <NUM> and <NUM>, all of the intervening portions 132a, all of the upper folded portions 132b and all of the lower folded portions 132c while being wound around a central axis parallel to the width direction. A terminal end 132e (see <FIG> and <FIG>) of the outermost covering portion 132d is configured not to overlap with the positive electrode active material layer <NUM> and the negative electrode active material layer <NUM> in the one direction. In the present embodiment, the terminal end 132e of the outermost covering portion 132d is provided below each of the electrodes <NUM> and <NUM>.

As illustrated in <FIG>, the outermost covering portion 132d is connected to each lower folded portion 132c. Specifically, as indicated by an arrow in <FIG>, heat is applied to a portion of the outermost covering portion 132d overlapping with each lower folded portion 132c from the outside of this portion by laser irradiation or the like. Thereby, the outermost covering portion 132d is connected (welded) to each lower folded portion 132c. At this time, each lower folded portion 132c is connected (welded) to the lower end of the negative electrode collector foil <NUM>.

The outermost covering portion 132d is connected to each upper folded portion 132b. Specifically, as indicated by arrows in <FIG>, heat is applied to a portion of the outermost covering portion 132d overlapping with each upper folded portion 132b from the outside of this portion by laser irradiation or the like. Thereby, the outermost covering portion 132d is connected (welded) to each upper folded portion 132b.

As illustrated in <FIG>, the plurality of negative electrodes <NUM> include an outermost negative electrode 120E disposed outermost in one direction. A lower end of the outermost negative electrode 120E is connected to the outermost covering portion 132d. An upper end of the outermost negative electrode 120E is connected to the outermost covering portion 132d. The lower end and the upper end of the outermost negative electrode 120E are connected to the outermost covering portion 132d by laser irradiation or the like in the same manner as described above.

The upper end of the positive electrode <NUM>, more specifically, the upper end of the positive electrode collector foil <NUM> may be connected to the upper folded portion 132b. Similarly, the lower end of the positive electrode collector foil <NUM> may be connected to the outermost covering portion 132d.

The insulating film <NUM> collectively covers the peripheral surface and bottom surface of the plurality of electrodes <NUM> and <NUM> and the separator <NUM>. In <FIG>, the insulating film <NUM> is indicated by dots.

The cell case <NUM> houses the electrode assembly <NUM>. The cell case <NUM> contains an electrolytic solution (not illustrated). The cell case <NUM> is sealed. The cell case <NUM> includes a case body <NUM> and a lid <NUM>.

The case body <NUM> has an opening that opens upward. The case body <NUM> is made of a metal such as aluminum. As illustrated in <FIG>, the case body <NUM> includes a bottom wall <NUM> and a peripheral wall <NUM>. The bottom wall <NUM> is formed in a rectangular flat plate shape. The peripheral wall <NUM> rises from the bottom wall <NUM>. The peripheral wall <NUM> is formed in a quadrangular cylindrical shape. The length of the peripheral wall <NUM> in the width direction is longer than the length of the peripheral wall <NUM> in the thickness direction. The length of the peripheral wall <NUM> in the height direction is longer than the length of the peripheral wall <NUM> in the thickness direction.

The lid <NUM> closes the opening of the case body <NUM>. The lid <NUM> is connected to the opening by welding or the like. The lid <NUM> is formed in a flat plate shape. The lid <NUM> is made of a metal such as aluminum. The lid <NUM> includes a pressure release valve <NUM> and a sealing member <NUM>.

The pressure release valve <NUM> is formed at a central portion of the lid <NUM>. The pressure release valve <NUM> is configured to break when the internal pressure of the cell case <NUM> becomes equal to or higher than a predetermined pressure. When the pressure release valve <NUM> is broken, the gas in the cell case <NUM> is released to the outside of the cell case <NUM> through the pressure release valve <NUM>, which reduces the internal pressure of the cell case <NUM>.

The sealing member <NUM> seals a liquid injection port h formed on the lid <NUM>. The liquid injection port h is a through hole for injecting an electrolytic solution into the cell case <NUM> in the manufacturing process of the power storage cell <NUM>. After the electrolytic solution is injected into the case body <NUM> through the liquid injection port h, the liquid injection port h is sealed by the sealing member <NUM>.

The pair of external terminals <NUM> is fixed to the cell case <NUM>. One of the pair of external terminals <NUM> is a positive external terminal, and the other is a negative external terminal. Each external terminal <NUM> is fixed to an upper surface of the lid <NUM> via an upper insulating portion <NUM> which will be described later. Each external terminal <NUM> is made of a metal such as aluminum. Each external terminal <NUM> is formed, for example, in a rectangular parallelepiped shape. A bus bar (not illustrated) is connected to each external terminal <NUM> by welding or the like.

The pair of connecting members <NUM> (see <FIG>) connects a plurality of electrode tabs 112p and a plurality of electrode tabs 122n to the pair of external terminals <NUM>, respectively. More specifically, one of the pair of connecting members <NUM> connects the plurality of positive electrode tabs 112p to the positive external terminal <NUM>, and the other connecting member <NUM> connects the plurality of negative electrode tabs 122n to the negative external terminal <NUM>. Since the pair of connecting members <NUM> have substantially the same structure, only one connecting member <NUM> will be described below.

The connecting member <NUM> includes a collector tab <NUM>, a subtab <NUM>, and a connecting pin <NUM>.

The collector tab <NUM> has a side portion <NUM> and an upper portion <NUM>. The side portion <NUM> is arranged on a side surface of the electrode assembly <NUM> in the width direction. The upper portion <NUM> is arranged on an upper surface of the electrode assembly <NUM>. The upper portion <NUM> extends inward in the width direction from an upper end of the side portion <NUM>.

The subtab <NUM> connects the plurality of positive electrode tabs 112p to the collector tab <NUM>. One end <NUM> of the subtab <NUM> is connected to the plurality of positive electrode tabs 112p by welding or the like, and the other end <NUM> of the subtab <NUM> is connected to the side portion <NUM> of the collector tab <NUM> by welding or the like.

The connecting pin <NUM> connects the collector tab <NUM> to the external terminal <NUM>. The connecting pin <NUM> connects the upper portion <NUM> to the external terminal <NUM>. Specifically, the lower end of the connecting pin <NUM> is inserted into a through hole provided on the upper portion <NUM> and is connected to the upper portion <NUM> by welding or the like, and the upper end of the connecting pin <NUM> is inserted into a through hole provided on the external terminal <NUM> and is connected to the external terminal <NUM> by welding, caulking or the like.

The insulating member <NUM> insulates the cell case <NUM> and the connecting member <NUM> from each other. The insulating member <NUM> includes an upper insulating portion <NUM>, a lower insulating portion <NUM>, an insulator <NUM>, and an insulating plate <NUM>.

The upper insulating portion <NUM> is fixed to the upper surface of the lid <NUM>. The upper insulating portion <NUM> is disposed between the lid <NUM> and the external terminal <NUM>. The upper insulating portion <NUM> is provided with an insertion hole through which the connecting pin <NUM> is inserted.

The lower insulating portion <NUM> is fixed to the lower surface of the lid <NUM>. The lower insulating portion <NUM> is disposed between the lid <NUM>, and the upper portion <NUM> and a lower portion of the connecting pin <NUM>. The lower insulating portion <NUM> is provided with an insertion hole through which the connecting pin <NUM> is inserted.

The insulator <NUM> is disposed between the connecting pin <NUM> and the lid <NUM>. The insulator <NUM> is formed in a cylindrical shape, and is configured to surround the connecting pin <NUM>.

The insulating plate <NUM> is fixed to the lower surface of the upper portion <NUM>. The insulating plate <NUM> is disposed on the electrode assembly <NUM>. A through hole is formed in a portion of the insulating plate <NUM> located below the pressure release valve <NUM> and a portion of the insulating plate <NUM> located below the liquid injection port h.

Next, a process of manufacturing the power storage cell <NUM> will be described with reference to <FIG>.

First, while the separator <NUM> is being formed in a zigzag shape, each electrode <NUM> and each electrode <NUM> are alternately disposed between a pair of intervening portions 132a. After winding the outermost covering portion 132d of the separator <NUM>, by irradiating a laser beam from the outside of the outermost covering portion 132d, for example, each lower folded portion 132c is connected (welded) to the outermost covering portion 132d, the lower end of each negative electrode collector foils <NUM> is connected (welded) to each lower folded portion 132c, each upper folded portion 132b is connected (welded) to the outermost covering portion 132d, and the lower end and the upper end of each outermost negative electrode 120E are connected (welded) to the outermost covering portion 132d.

Next, as illustrated in <FIG>, one end <NUM> of the subtab <NUM> is connected to the plurality of electrode tabs 112p and 122n by welding or the like. Then, as indicated by arrows in <FIG>, one end <NUM> and the plurality of electrode tabs 112p and 122n are bent in such a manner that the end <NUM> of the subtab <NUM> is in contact with the side portion <NUM> of the collector tab <NUM>.

Subsequently, as illustrated in <FIG>, after the peripheral surface and bottom surface of the plurality of electrodes <NUM>, <NUM> and the separator <NUM> are collectively covered with the insulating film <NUM>, the electrode assembly <NUM> is inserted into the case body <NUM>. Then, the lid <NUM> is welded to the case body <NUM> to close the opening.

Thereafter, the electrolytic solution is supplied into the cell case <NUM> through the liquid injection port h, and the liquid injection port h is sealed with the sealing member <NUM>.

As described above, in the electrode assembly <NUM> according to the present embodiment, since the separator <NUM> is formed in a zigzag shape and each lower folded portion 132c is connected to the negative electrode <NUM>, at least the positional displacement of the negative electrode <NUM> with respect to the separator <NUM> is prevented.

Further, since each lower folded portion 132c is connected to the outermost covering portion 132d, the relative displacement between the lower folded portions 132c is prevented. In addition, since the positive electrode <NUM> is disposed in a space surrounded by a pair of the lower folded portion 132c and the upper folded portion 132b adjacent to each other, the positional displacement of the positive electrode <NUM> with respect to the separator <NUM> is further prevented.

In the above embodiment, the negative electrode <NUM> is disposed above the lower folded portion 132c and the lower folded portion 132c is connected to the lower end of the negative electrode <NUM>, but the positive electrode <NUM> may be disposed above the lower folded portion 132c and the lower folded portion 132c may be connected to the lower end of the positive electrode <NUM>.

Claim 1:
An electrode assembly (<NUM>) comprising:
a plurality of electrodes (<NUM>, <NUM>) arranged side by side in one direction; and
a separator (<NUM>) formed in a zigzag shape and configured to insulate the plurality of electrodes from each other,
wherein
each of the plurality of electrodes (<NUM>, <NUM>) includes:
an electrode collector foil (<NUM>,<NUM>), and
an electrode active material layer (<NUM>,<NUM>) provided on both surfaces of the electrode collector foil,
the separator includes:
a plurality of intervening portions (132a), each of which is interposed between a pair of electrodes adjacent to each other in the one direction;
an upper folded portion (132b) which connects an upper end of one intervening portion of the plurality of intervening portions and an upper end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on one side of the one direction;
a lower folded portion (132c) which connects a lower end of the one intervening portion of the plurality of intervening portions and a lower end of another intervening portion of the plurality of intervening portions which is adjacent to the one intervening portion on the other side of the one direction; and
an outermost covering portion (132d) which collectively covers the upper folded portion and the lower folded portion,
at least one of the upper folded portion and the lower folded portion is welded to the electrode collector foil of the electrode, and
the lower folded portion and the upper folded portion are welded to the outermost covering portion.