Patent Description:
In recent years, in the automobile industry, advanced electronics industry, and the like, the demand for automobile batteries and batteries for electronic devices is increasing, and there are demands particularly for a reduction in size and thickness, higher capacities, and the like. Of the above, nonaqueous electrolyte secondary batteries, which have higher energy densities compared to other batteries, are attracting attention.

The manufacturing steps of such nonaqueous electrolyte secondary batteries include a step to form a roll electrode by winding an electrode around the outer circumference of a core that has a substantially circular outer circumference into a roll shape. A roll electrode is subjected to heat treatment to remove moisture and the like contained therein, and then cut into the required length (for example, Patent Document <NUM>).

Patent Document <NUM> discloses a method of fixing an original printing plate at the start of winding to a hollow core using tape, in the field of roll-shaped original printing plates with a long original printing plate wound around a hollow core. It also discloses that the thickness of this tape is equal to or less than <NUM>-<NUM>% of the thickness of the original printing plate. According to this roll-shaped original printing plate, it is possible to carry out winding without the stepped shape at the start of winding, which occurs near the hollow core, being transferred, and winding up can be carried out in a good state without generating loosening in the winding or tightening of the winding, to thereby improve the quality.

<CIT> and <CIT> each discloses a roll electrode comprising: a core extending in an axial direction and having a substantially circular outer circumference; an electrode having an expansion coefficient that is lower than an expansion coefficient of the core and being wound into a roll shape on the outer circumference of the core; and a fixing part fixing an end portion from which the electrode starts being wound around the core.

Here, there are cases in which a roll electrode, such as that disclosed in Patent Document <NUM>, is transported to the place where cutting is carried out after being subjected to heat treatment. The present inventors found a problem in that a phenomenon occurs in which, when transporting the roll electrode after carrying out the heat treatment described above, the electrode that is wound into a roll shape is shifted in the axial direction with respect to the core (so-called winding deviation). Furthermore, according to evaluations made by the present inventors, this problem occurs particularly when the expansion coefficient of the core that configures the roll electrode is higher than the expansion coefficient of the electrode. The cause of the problem was found to be that, when the heat treatment is applied, the electrode receives a compressive force from the core and a gap is generated after the heat treatment between the core and the electrode as well as between electrodes. Furthermore, it was found that generation of a winding deviation cannot be prevented, even if the end portion from which the electrode starts being wound around the core is fixed, as in the technique disclosed in Patent Document <NUM> described above.

The present invention was done to solve the problem described above, and an object thereof is to provide a means capable of suppressing the generation of winding deviation in a roll electrode in which the expansion coefficient of a core is higher than that of an electrode.

The roll electrode according to the present invention that achieves the object described above comprises a core that extends in the axial direction and has a substantially circular outer circumference, and an electrode that has an expansion coefficient that is lower than the expansion coefficient of the core and that is wound into a roll shape on the outer circumference of the core. Additionally, the roll electrode comprises a fixing part for fixing an end portion from which the electrode starts being wound around the core, and a tape member that fixes an intermediate portion between the winding start end portion and a winding finish end portion of the electrode to the core, so as to regulate the axial movement of the electrode wound into the roll shape with respect to the core.

In addition, in the method for manufacturing a roll electrode according to the present invention that achieves the object described above, a winding-start end portion of an electrode that has an expansion coefficient that is lower than the expansion coefficient of a core is fixed to the core, which extends in the axial direction and has a substantially circular outer circumference. Then, the electrode is wound into a roll shape around the outer circumference of the core up to an intermediate portion between the winding-start end portion and the winding-finish end portion of the electrode. Then, the intermediate portion is fixed to the core using tape, and the electrode is wound into a roll shape around the outer circumference of the core up to the winding-finish end portion.

In addition, the roll electrode according to the present invention that achieves the object described above comprises a core that extends in the axial direction and has a substantially circular outer circumference, and an electrode that has an expansion coefficient that is lower than the expansion coefficient of the core and that is wound into a roll shape on the outer circumference of the core. Additionally, the roll electrode comprises a fixing part for fixing an end portion from which the electrode starts being wound around the core, and a pair of ring plates that is disposed on both sides in the axial direction of the electrode wound into the roll shape, and that is fixed to the outer circumference of the core, so as to regulate the axial movement of the electrode wound into the roll shape with respect to the core. Outer circumference of the ring plates are configured to be on the inner circumferential side of the central portion between the outermost perimeter and the innermost perimeter of the electrode, which is arranged in the roll shape, as viewed from the axial direction.

In addition, in the method for manufacturing a roll electrode according to the present invention that achieves the object described above, a winding-start end portion of an electrode that has an expansion coefficient that is lower than the expansion coefficient of a core is fixed to the core, which extends in the axial direction and has a substantially circular outer circumference. Then, the electrode is wound into a roll shape around the outer circumference of the core up to the winding-finish end portion of the electrode. Then a pair of ring plates, outer circumferences of which are configured to be on the inner circumferential side of the central portion between the outermost perimeter and the innermost perimeter of the electrode, which is arranged in the roll shape, as viewed from the axial direction, is disposed and fixed on both sides in the axial direction of the electrode that is wound into the roll shape on the outer circumference of the core.

In addition, in the method for manufacturing a roll electrode according to the present invention that achieves the object described above, a pair of ring plates, the outer circumferences of which are configured to be on the inner circumferential side of the central portion between the outermost perimeter and the innermost perimeter of the electrode, which is arranged in a roll shape, as viewed from the axial direction, are disposed and fixed on the outer circumference of a core that extends in the axial direction and has a substantially circular outer circumference, at a predetermined distance from each other in the axial direction. Then, a winding-start end portion of an electrode that has an expansion coefficient that is lower than the expansion coefficient of a core is fixed to the core between the pair of ring plates. Then, the electrode is wound into the roll shape around the outer circumference of the core up to the winding-finish end portion of the electrode.

The roll electrode configured as described above comprises a regulating part for regulating the axial movement of the electrode wound into a roll shape with respect to the core. Accordingly, it is possible to prevent a winding deviation, which occurs due to a gap being generated between the core and the electrode as well as between electrodes after the heat treatment, in a roll electrode in which the expansion coefficient of the core is higher than the expansion coefficient of the electrode.

Additionally, according to the method for manufacturing a roll electrode configured as described above, an intermediate portion between the winding-start end portion and the winding-finish end portion of an electrode is fixed to the core using tape. Accordingly, the fixing force of the electrode to the core is enhanced. Therefore, it is possible to suppress the generation of winding deviation in a roll electrode in which the expansion coefficient of a core is higher than the expansion coefficient of an electrode.

Furthermore, according to the method for manufacturing a roll electrode configured as described above, ring plates are disposed on both sides in the axial direction of the electrode that is wound into a roll shape. Accordingly, it is possible to suppress the generation of winding deviation in a roll electrode in which the expansion coefficient of a core is higher than the expansion coefficient of an electrode using the ring plates.

The first embodiment according to the present invention will be described below, with reference to the appended drawings. In the explanations of the drawings, the same elements are given the same reference symbols, and overlapping explanations are omitted. The dimensional ratios in the drawings are exaggerated for convenience of explanation, and are different from the actual ratios.

<FIG> is a perspective view illustrating a roll electrode according to the first embodiment. <FIG> is a perspective view illustrating a state in which a winding-start end portion of an electrode is fixed to a core using a first tape member. <FIG> is a perspective view illustrating a state in which an electrode has been wound around the core once. <FIG> is a perspective view illustrating a state in which an intermediate portion of an electrode is fixed to a core using a second tape member.

The roll electrode <NUM> according to the first embodiment comprises a cylindrical core <NUM> that extends in the axial direction (left/right direction in <FIG>), and an electrode <NUM> that is wound into a roll shape on the outer circumference of the core <NUM>, as illustrated in <FIG>. The roll electrode <NUM> further comprises a first tape member (corresponding to the fixing part) <NUM> that fixes a winding-start end portion <NUM> of the electrode <NUM> to the core <NUM>, and a second tape member (corresponding to the regulating part) <NUM> that fixes an intermediate portion <NUM> of the electrode <NUM> to the core <NUM>.

The core <NUM> has a through-hole <NUM> that extends therethrough in the axial direction, as illustrated in <FIG>. A rotatable winding shaft (not shown) is inserted in the through-hole <NUM> when winding the electrode <NUM> around the core <NUM>. The core <NUM> is not limited as long as the outer circumference is substantially circular, and may have a columnar shape or the like.

The material that constitutes the core <NUM> is, for example, aluminum. However, the material is not limited thereto, and may be another metal material as long as the metal has a higher thermal expansion coefficient than the thermal expansion coefficient of the electrode <NUM>.

The electrode <NUM> comprises a current collector and an active material layer. An example of a method for layering an active material layer on the current collector is a method to coat, and dry, an electrode slurry on the current collector, but no limitation is imposed thereby. The electrode <NUM> may be configured such that an active material layer is layered on both sides of the current collector, or such that an active material layer is layered on one side of the current collector.

The electrode <NUM> comprises a negative electrode and a positive electrode.

A member that is conventionally used as a battery current collector may be appropriately employed as the material constituting the negative electrode current collector. Examples include aluminum, nickel, iron, stainless steel (SUS), titanium, and copper. Of the above, copper is preferable as a negative electrode current collector from the point of view of electron conductivity and battery operating potential. The thickness of the negative electrode current collector is not particularly limited, and is set giving consideration to the intended use of the battery.

The negative electrode active material layer is, for example, hard carbon (non-graphitizable carbon material). However, no limitation is imposed thereby, and it is also possible to use a graphite carbon material or a lithium-transition metal composite oxide. In particular, a negative electrode active material comprising carbon and lithium-transition metal composite oxide is favorable from the point of view of capacity and output characteristics.

The same material constituting the negative electrode current collector may be used as the material constituting the positive electrode current collector. Of the above, aluminum is preferable as a positive electrode current collector from the point of view of electron conductivity and battery operating potential. However, no limitation is imposed thereby, and it is also possible to use an aluminum foil, a clad material of nickel and aluminum, a clad material of copper and aluminum, or plating material of a combination of these metals. The thickness of the positive electrode current collector is not particularly limited, and is set giving consideration to the intended use of the battery.

An example of a material constituting the positive electrode active material layer is LiMn<NUM>O<NUM>. However, no particular limitation is imposed thereby. It is preferable to apply lithium-transition metal composite oxide, from the point of view of capacity and output characteristics.

In the present invention, it is necessary for the combination of the current collector and the active material layer of the electrode <NUM> to be a combination in which a gap is generated between the core <NUM> and the electrode <NUM> after heat treatment, as described later. That is, it is necessary for the combination to have, as the electrode <NUM> as a whole, a lower thermal expansion coefficient than the thermal expansion coefficient of the core <NUM>.

The first tape member <NUM> fixes the winding-start end portion <NUM> of the electrode <NUM> to the core <NUM>, as illustrated in <FIG>. The first tape member <NUM> is attached across the entire region in the axial direction of the winding-start end portion <NUM> of the electrode <NUM>. The winding -start end portion <NUM> is the position from which the electrode <NUM> starts being wound around the core <NUM>.

The first tape member <NUM> has adhesiveness on the lower surface side in <FIG>.

For example, a tape that uses an acrylic adhesive may be used as the first tape member <NUM>, but no limitation is imposed thereby, and any tape member that is capable of fixing the winding-start end portion <NUM> of the electrode <NUM> to the core <NUM> may be used.

The second tape member <NUM> fixes an intermediate portion <NUM> between the winding-start end portion <NUM> and the winding-finish end portion <NUM> of the electrode <NUM> to the core <NUM>, as illustrated in <FIG>. The winding-finish end portion <NUM> is the position where the electrode <NUM> is finished being wound around the core <NUM> (refer to <FIG>).

The second tape member <NUM> has adhesiveness on the lower surface side in <FIG>.

In the present embodiment, the intermediate portion <NUM> is located in a winding region of the electrode <NUM> that is wound around the core <NUM> during the second turn, as illustrated in <FIG>. That is, the second tape member <NUM> is attached to the outer circumference of the winding region of the electrode <NUM> that is wound around the core <NUM> during the second turn, and fixes the intermediate portion <NUM> to the core <NUM>.

Meanwhile, due to thermal expansion of the core <NUM> and the electrode <NUM> using a heat treatment for removing moisture, and the like, the core <NUM> presses the electrode <NUM> radially outward. Consequently, the surface roughness of the winding region of the electrode <NUM> that is wound around the core <NUM> during the first turn is particularly reduced. If the second tape member <NUM> is attached to the winding region of the first turn, where the surface roughness has been reduced, the adhesive force of the second tape member <NUM> with respect to the winding region of the electrode <NUM> that is wound around the core <NUM> during the first turn is reduced, and the effect to suppress winding deviation is decreased. Therefore, it is preferable for the second tape member <NUM> to avoid the winding region of the electrode <NUM> that is wound around the core <NUM> during the first turn, and to be attached to the winding region that is wound around during the second turn or later. However, the present invention includes a mode in which the second tape member <NUM> is attached to the winding region of the electrode <NUM> that is wound around the core <NUM> during the first turn.

The second tape member <NUM> is attached to the intermediate portion <NUM> of the electrode <NUM> across the entire region in the axial direction, as illustrated in <FIG>.

The second tape member <NUM> is disposed in a different position in the circumferential direction with respect to the first tape member <NUM> when viewed from the axial direction, as illustrated in <FIG>. By disposing the second tape member <NUM> in this manner, compared to when being disposed in the same position in the circumferential direction, the height of the step that is generated radially outward, caused by the thicknesses of the first tape member <NUM> and the second tape member <NUM>, can be reduced. Therefore, it is possible to suppress the occurrence of loosening in the winding or tightening of the winding, when winding the electrode <NUM> around the core <NUM>. The second tape member <NUM> may be disposed in the same position in the circumferential direction, with respect to the first tape member <NUM>.

The same material that constitutes the first tape member <NUM> may be used as the material constituting the second tape member <NUM>.

Next, the method for manufacturing a roll electrode <NUM> according to the first embodiment will be described.

First, the winding-start end portion <NUM> of the electrode <NUM> is fixed to the core <NUM> by the first tape member <NUM>, as illustrated in <FIG>.

Next, the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM>, up to the intermediate portion <NUM> between the winding-start end portion <NUM> and the winding-finish end portion <NUM>.

Next, the intermediate portion <NUM> is fixed to the core <NUM> by the second tape member <NUM>, as illustrated in <FIG>.

Then, the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM> up to the winding-finish end portion <NUM> (refer to <FIG>).

Next, the effect of the roll electrode <NUM> according to the first embodiment will be described, with reference to <FIG> are views for explaining the mechanism by which a winding deviation occurs. Specifically, <FIG> is a view illustrating a roll electrode <NUM> before heat treatment; <FIG> is a side surface view, and <FIG> is a schematic cross-sectional view taken along section line 5B-5B in <FIG>. <FIG> is a view illustrating a roll electrode <NUM> immediately after heat treatment; <FIG> is a side surface view, and <FIG> is a schematic cross-sectional view taken along section line 6B-6B in <FIG>. <FIG> is a view illustrating a roll electrode <NUM> when the temperature has returned to the atmospheric temperature after heat treatment; <FIG> is a side surface view, and <FIG> is a schematic cross-sectional view taken along section line 7B-7B in <FIG>. <FIG> is a schematic view illustrating the state of a winding deviation. <FIG> is a view for explaining the effect of the roll electrode <NUM> according to the present embodiment. In <FIG>, the first tape member <NUM> is omitted for ease of understanding. In addition, the hatching is omitted in <FIG>, <FIG>, and <FIG>. Furthermore, a side surface view is as viewed from the axial direction.

First, the mechanism by which a winding deviation occurs will be described, with reference to <FIG>.

Heat treatment is carried out for the purpose of removing moisture, and the like, present inside the roll electrode, with respect to a roll electrode in which an electrode <NUM> is wound around a core <NUM>, as illustrated in <FIG>. Heat treatment entails, for example, vacuum drying carried out for <NUM> hours at <NUM>.

As a result, the core <NUM> and the electrode <NUM> are thermally expanded, as illustrated in <FIG>. More specifically, the core <NUM> expands so as to spread radially inward and radially outward. In addition, the electrode <NUM> expands so as to spread radially outward. Since the core <NUM> and the electrode <NUM> are thermally expanded in this manner, the electrode <NUM> receives a compressive force from the core <NUM> in the vicinity of the winding-start end portion <NUM> of the electrode <NUM> (refer to the arrow in <FIG>). As a result, the current collector of the electrode <NUM> is plastically deformed in the vicinity of the winding-start end portion <NUM>, and the minute gap between the electrodes <NUM> that is generated when winding the electrode <NUM> around the core <NUM> is filled. Therefore, the thickness W of the electrode <NUM> decreases toward the inner circumferential side where the winding-start end portion <NUM> is located, as illustrated in <FIG>.

Then, when the temperature returns to atmospheric temperature after the heat treatment, the core <NUM> returns to the shape before the heat treatment, as illustrated in <FIG>. In contrast, the current collector of the electrode <NUM> is plastically deformed at the time of the heat treatment, as described above, and the minute gap between the electrodes <NUM> that is generated when winding the electrode <NUM> around the core <NUM> is filled; therefore, the shape of the electrode does not return to the shape before the heat treatment, and becomes the shape illustrated in <FIG>. Specifically, a gap S1 is formed between the core <NUM> and the electrode <NUM>, and a gap S2 is also formed between the electrodes <NUM> in the vicinity of the winding-start end portion <NUM>. The gap S2 is formed smaller than the gap S1, and is formed to become smaller from the inner circumferential side to the outer circumferential side of the core <NUM>.

When a roll electrode, in which gaps S1 and S2 are formed in this manner, is transported, in the event a second tape member <NUM> is not provided as a comparative example, a winding deviation occurs, in which the electrode <NUM> moves in the axial direction with respect to the core <NUM>, as illustrated in <FIG> (refer to the arrow in <FIG>). The winding deviation occurs particularly on the inner circumferential side of the electrode <NUM> where the winding-start end portion <NUM> is located, as illustrated in <FIG>.

In contrast, by fixing the intermediate portion <NUM> to the core <NUM> using the second tape member <NUM> as illustrated in <FIG>, the fixing force of the electrode <NUM> to the core <NUM> is enhanced. Accordingly, it is possible to suppress an occurrence of winding deviation. As described above, since a winding deviation tends to occur on the inner circumferential side of the electrode <NUM>, it is preferable for the second tape member <NUM> to be attached on the inner circumferential side of the electrode <NUM>, which is wound into a roll shape.

As described above, the roll electrode <NUM> according to the first embodiment comprises a cylindrical core <NUM> that extends in the axial direction and an electrode <NUM> that has an thermal expansion coefficient that is lower than the thermal expansion coefficient of the core <NUM> and that is wound into a roll shape on the outer circumference of the core <NUM>. The roll electrode <NUM> further comprises a first tape member <NUM> for fixing the winding-start end portion <NUM> of the electrode <NUM> to the core <NUM> and a second tape member <NUM> for regulating the axial movement of the electrode <NUM> wound into a roll shape with respect to the core <NUM>. Accordingly, it is possible to suppress the generation of winding deviation in a roll electrode <NUM> in which the thermal expansion coefficient of the core <NUM> is higher than the thermal expansion coefficient of the electrode <NUM> by the second tape member <NUM>.

In addition, the second tape member <NUM> is a tape member that fixes the intermediate portion <NUM> between the winding-start end portion <NUM> and the winding-finish end portion <NUM> of the electrode <NUM> to the core <NUM>. Accordingly, the fixing force of the electrode <NUM> to the core <NUM> is enhanced by the second tape member <NUM>. Therefore, it is possible to suppress an occurrence of winding deviation using an easy method to attach the second tape member <NUM> to the core <NUM> and the intermediate portion <NUM>.

Therefore, the second tape member <NUM> fixes the intermediate portion <NUM> located in the winding region of the electrode <NUM> that is wound around the core <NUM> during the second turn to the core <NUM>. Accordingly, the inner circumferential side of the electrode <NUM>, where winding deviation particularly occurs, is fixed to the core <NUM> using the second tape member <NUM>. Therefore, it is possible to favorably suppress an occurrence of winding deviation. Furthermore, since the second tape member <NUM> is attached while avoiding the winding region of the electrode during the first turn, where the surface roughness is reduced by the heat treatment, as described above, it is possible to more favorably suppress an occurrence of winding deviation.

In addition, the first tape member <NUM> and the second tape member <NUM> are disposed in different positions from each other in the circumferential direction when viewed from the axial direction. Accordingly, compared to when the first tape member <NUM> and the second tape member <NUM> are disposed in the same position in the circumferential direction, the height of the step that is generated radially outward, due to the thicknesses of the first tape member <NUM> and the second tape member <NUM>, can be reduced. Therefore, it is possible to suppress the occurrence of loosening in the winding or tightening of the winding, when winding the electrode <NUM> around the core <NUM>.

In addition, as described above, in the method for manufacturing a roll electrode <NUM> according to the first embodiment, the winding-start end portion <NUM> of the electrode <NUM>, having a lower thermal expansion coefficient than the thermal expansion coefficient of the core <NUM>, is fixed to the cylindrical core <NUM> that extends in the axial direction. Then, the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM>, up to the intermediate portion <NUM> between the winding-start end portion <NUM> and the winding-finish end portion <NUM>. Then, the intermediate portion <NUM> is fixed to the core <NUM> using the second tape member <NUM>, and the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM> up to the winding-finish end portion <NUM>. According to this manufacturing method, the intermediate portion <NUM> between the winding-start end portion <NUM> and the winding-finish end portion <NUM> is fixed to the core <NUM> using the second tape member <NUM>. Accordingly, the fixing force of the electrode <NUM> to the core <NUM> is enhanced. Therefore, it is possible to suppress the generation of winding deviation in the roll electrode <NUM> in which the thermal expansion coefficient of the core <NUM> is higher than the thermal expansion coefficient of the electrode <NUM>.

Next, modified examples of the roll electrode <NUM> according to the first embodiment will be described.

<FIG> is a perspective view illustrating a roll electrode <NUM> according to the modified example <NUM>. In the first embodiment described above, the second tape member <NUM> is attached to the intermediate portion <NUM> of the electrode <NUM> across the entire region in the axial direction. However, the second tape member <NUM> may be provided shorter than the width W1 of the electrode <NUM> along the axial direction, and at least an edge <NUM> of the electrode <NUM> along a direction intersecting the axial direction may be fixed to the core <NUM>, as illustrated in <FIG>. According to this configuration, it is possible to reduce the amount of the second tape member <NUM> that is used compared to the first embodiment; therefore, the roll electrode <NUM> can be manufactured at a low cost.

Furthermore, in the case of the second tape member <NUM> described above, the electrode <NUM> in the winding region of the third turn comes in contact with an exposed portion <NUM> where the electrode <NUM> is exposed, located between the second tape members <NUM>. Accordingly, if the surface roughness of the electrode <NUM> is greater than that of the second tape member <NUM>, the frictional force between the winding region of the second turn and the winding region of the third turn of the electrode <NUM> is increased, compared to a configuration in which the second tape member <NUM> is attached to the intermediate portion <NUM> across the entire region in the axial direction. Therefore, it is possible to more favorably suppress an occurrence of winding deviation.

<FIG> is a perspective view illustrating a roll electrode <NUM> according to the modified example <NUM>. In the above-described first embodiment, the second tape member <NUM> fixes the intermediate portion <NUM> located in the winding region of the electrode <NUM> that is wound around the core <NUM> during the second turn to the core <NUM>. However, the intermediate portion <NUM>, which is fixed to the core <NUM>, may be positioned on the inner circumferential side of the central portion 20C of the outermost perimeter 20A and the innermost perimeter 20B of the electrode <NUM>, which is arranged in a roll shape, as viewed from the axial direction, as illustrated in <FIG>. By fixing the intermediate portion <NUM>, positioned on the inner circumferential side of the central portion 20C, to the core <NUM> using the second tape member <NUM>, it is possible to fix the inner circumferential side of the electrode <NUM> where a winding deviation particularly occurs. An intermediate portion <NUM> that is fixed to the core <NUM> may be positioned on the outer circumferential side of the central portion 20C, as illustrated in <FIG>.

In the first embodiment described above, a single-sided tape having adhesiveness on one side was used for the first tape member <NUM> and the second tape member <NUM>. However, the first tape member <NUM> and the second tape member <NUM> may be a double-sided tape having adhesiveness on both sides.

In the first embodiment described above, the core <NUM> is configured from a metal material having a higher thermal expansion coefficient than the core <NUM>, such as aluminum. However, the core may be a paper tube. A paper tube expands and contracts due to absorption of moisture. Therefore, since winding deviation occurs with transportation even if the core is a paper tube, it is possible to suppress an occurrence of winding deviation by fixing the intermediate portion <NUM> of the electrode <NUM> to the core using the second tape member <NUM>. Therefore, in the present invention, the concept of the expansion coefficient includes the concepts of both a thermal expansion coefficient due to heat treatment and an expansion coefficient due to absorption of moisture.

The first embodiment of the present invention is explained in further detail below with examples, but the present invention is not limited only to these examples.

First, the method of forming the electrode <NUM> is described. Here, particularly the negative electrode of the electrode <NUM> will be described as an example. First, a negative electrode slurry was prepared by dispersing massive artificial graphite (MAGD manufactured by Hitachi Chemical Co. ): PVdF (polyvinylidene fluoride, binder) in NMP (N-methylpyrrolidone) at a composition ratio of <NUM>:<NUM>. Thereafter, the negative electrode slurry was coated onto the surface of a Cu foil having a thickness of <NUM> using a die coater, and a negative electrode was prepared by float drying at <NUM>. Thereafter, pressing was carried out to pack the negative electrode to a density of <NUM>/cc. The thickness of the electrode <NUM> was <NUM>.

Next, the electrode <NUM> was wound around the core <NUM> to produce a roll electrode <NUM>. The winding length per one electrode was set to <NUM>. The outer diameter of the core was <NUM>.

Examples <NUM>-<NUM> and comparative examples <NUM>-<NUM> will be described below.

Aluminum was used as the material of the core. In addition, the fixing method illustrated in <FIG> and described in the first embodiment was used as the fixing method. The second tape member <NUM> was fixed in a position separated from the first tape member <NUM> by <NUM>.

Aluminum was used as the material of the core. In addition, the fixing method illustrated in <FIG> and described in Modified Example <NUM> was used as the fixing method. The second tape member <NUM> was fixed in a position separated from the first fixing portion by <NUM>.

A paper tube was used as the material of the core. In addition, the fixing method illustrated in <FIG> and described in the first embodiment was used as the fixing method.

Aluminum was used as the material of the core. In addition, only the first tape member <NUM> was used and a second tape member <NUM> was not used as the fixing method.

A paper tube was used as the material of the core. In addition, only the first tape member <NUM> was used and a second tape member <NUM> was not used as the fixing method.

Next, the roll electrodes according to Examples <NUM>-<NUM> and Comparative Examples <NUM>-<NUM> were subjected to a thermohygrostat bath test or a heat treatment test. Each of the test methods will be described below.

The thermohygrostat bath test will be described. Specifically, roll electrodes were placed in a thermohygrostat bath to carry out a heat cycle test. The conditions were as follows.

Twenty sets of the cycle (i)-(iv) above were carried out.

The heat treatment test will be described. Specifically, roll electrodes were placed in a vacuum drying furnace to carry out vacuum drying for <NUM> hours at a temperature of <NUM>.

Next, a load test was carried out on the roll electrode subjected to the thermohygrostat bath test or the heat treatment test. Specifically, roll electrodes were placed in a transport case, and a stop/go test was carried out using a forklift. The conditions were as follows. Speed: <NUM>/h, number of stop/go: three, load direction: axial direction.

Next, the method of evaluating the winding deviation amount will be described.

A score line L was drawn, and the winding deviation amount D after the above-described load test was measured, as illustrated in <FIG>.

The evaluation results of the winding deviation amount of Examples <NUM>-<NUM> and Comparative Examples <NUM>-<NUM> are shown together in Table <NUM>.

From the results of Examples <NUM>, <NUM> and Comparative Example <NUM>, it was confirmed that generation of winding deviation that occurs when transporting a roll electrode could be suppressed using the first embodiment and modified example <NUM> of the present invention.

In addition, by comparing Example <NUM> according to the first embodiment and Example <NUM> according to Modified Example <NUM>, it can be seen that generation of winding deviation can be more favorably suppressed using Example <NUM> according to Modified Example <NUM>. This is because, as described above, if the surface roughness of the electrode <NUM> is greater than that of the second tape member <NUM>, the frictional force between the winding region of the second turn and the winding region of the third turn of the electrode <NUM> is increased, by an exposed portion <NUM> where the electrode <NUM> is exposed being provided between the second tape members <NUM>.

In addition, from the results of comparative example <NUM> and Example <NUM>, it was confirmed that generation of winding deviation can be suppressed even if a paper tube is used as the core material instead of aluminum. This is because a paper tube expands and contracts by absorbing moisture, and demonstrates that the present invention is effective not only with respect to thermal expansion, but is effective in cases where there is a difference between the expansion/contraction ratios of the core and the electrode due to any physical factor, such as moisture and heat.

Next, the second embodiment of the present invention will be described. Descriptions of portions shared with the first embodiment will be omitted, and portions characteristic only to the second embodiment will be described. The roll electrode <NUM> according to the second embodiment is different from the roll electrode <NUM> according to the first embodiment in the means for suppressing generation of winding deviation.

<FIG> is a perspective view illustrating a roll electrode <NUM> according to the second embodiment. <FIG> is a cross-sectional view taken along the <NUM>-<NUM> line of <FIG>.

The roll electrode <NUM> according to the second embodiment comprises a core <NUM>, an electrode <NUM>, a first tape member <NUM>, and a ring plate (corresponding to the regulating part) <NUM>, as illustrated in <FIG>. The configurations of the electrode <NUM> and the first tape member <NUM> are the same as the configuration of the roll electrode <NUM> according to the first embodiment, and thus descriptions thereof are omitted.

The core <NUM> comprises a through-hole <NUM> extending in the axial direction and two groove portions 113A, 113B provided to the outer perimeter portion <NUM>, as illustrated in <FIG>.

The two groove portions 113A, 113B are provided on both sides of the electrode <NUM> in the axial direction, as illustrated in <FIG>. Protrusions <NUM> of the ring plate <NUM>, described later, are fitted to the two groove portions 113A, 113B.

The ring plate <NUM> regulates the axial movement of the electrode <NUM> wound into a roll shape with respect to the core <NUM>. Two ring plates <NUM> are disposed on both sides of the electrode <NUM> wound into a roll shape in the axial direction.

The ring plate <NUM> comprises a main body portion <NUM>, a recess <NUM> provided on the inner circumferential side of the main body portion <NUM>, an elastic member <NUM> disposed in the recess <NUM>, and a protrusion <NUM> to which a radially inward biasing force is applied by the elastic member <NUM>, as illustrated in <FIG>.

The outer circumference of the main body portion <NUM> is configured to be on the inner circumferential side of the central portion 20C between the outermost perimeter 20A and the innermost perimeter 20B of the electrode <NUM>, which is arranged in a roll shape, as viewed from the axial direction. The outer circumference of the main body portion <NUM> may be configured to exceed the central portion 20C to be on the outer circumferential side.

The elastic member <NUM> is fixed to the recess <NUM>. The protrusion <NUM> is fixed to the elastic member <NUM>. The respective fixing means are not particularly limited.

The protrusion <NUM> is imparted with a radially inward biasing force by the elastic member <NUM> and is fitted to the two groove portions 113A, 113B of the core <NUM>. The ring plate <NUM> is thereby fixed to the outer circumference of the core <NUM>.

According to a roll electrode <NUM> configured in this manner, ring plates <NUM> are disposed on both sides in the axial direction of the electrode <NUM> that is wound into a roll shape. Accordingly, it is possible to suppress the generation of winding deviation in the roll electrode <NUM> in which the expansion coefficient of the core <NUM> is higher than the expansion coefficient of the electrode <NUM> by the ring plates <NUM>.

Next, the method for manufacturing a roll electrode <NUM> according to the second embodiment will be described.

First, the winding-start end portion <NUM> of the electrode <NUM> is fixed to the core <NUM> using the first tape member <NUM>.

Then, the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM> up to the winding-finish end portion <NUM> of the electrode <NUM>.

Then, ring plates <NUM> are disposed and fixed on both sides in the axial direction of the electrode <NUM> that is wound into a roll shape, on the outer circumference of the core <NUM>. At this time, the protrusion <NUM> of the ring plate <NUM> is imparted with a radially inward biasing force by the elastic member <NUM> and is fitted to the two groove portions 113A, 113B of the core <NUM>.

The manufacturing method is not limited to the manufacturing method described above and may be a manufacturing method in which the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM>, after the ring plates <NUM> are disposed and fixed on the outer circumference of the core <NUM>.

As described above, the ring plates <NUM> of the roll electrode <NUM> according to the second embodiment are fixably disposed on the outer circumference of the core <NUM>, on both sides in the axial direction of the electrode <NUM>, which is wound into a roll shape. Accordingly, it is possible to suppress the generation of winding deviation in the roll electrode <NUM> in which the thermal expansion coefficient of the core <NUM> is higher than the thermal expansion coefficient of the electrode <NUM> by the ring plates <NUM>.

Additionally, the outer circumference of the ring plate <NUM> is configured to be on the inner circumferential side of the central portion 20C between the outermost perimeter 20A and the innermost perimeter 20B of the electrode <NUM>, which is arranged in a roll shape, as viewed from the axial direction. Accordingly, it is possible to regulate the movement on the inner circumferential side, where winding deviation particularly occurs.

In addition, as described above, in the method for manufacturing a roll electrode <NUM> according to the second embodiment, the winding-start end portion <NUM> of the electrode <NUM>, having a lower thermal expansion coefficient than the thermal expansion coefficient of the core <NUM>, is fixed to the cylindrical core <NUM> that extends in the axial direction. Then, the electrode <NUM> is wound into a roll shape around the outer circumference of the core <NUM> up to the winding-finish end portion <NUM> of the electrode <NUM>, and plates <NUM> are disposed and fixed on both sides in the axial direction of the electrode <NUM> that is wound into a roll shape, on the outer circumference of the core <NUM>. Accordingly, it is possible to suppress the generation of winding deviation in the roll electrode <NUM> in which the thermal expansion coefficient of the core <NUM> is higher than the thermal expansion coefficient of the electrode <NUM> by the ring plates <NUM>.

Claim 1:
A roll electrode (<NUM>, <NUM>, <NUM>) comprising:
a core (<NUM>) extending in an axial direction and having a substantially circular outer circumference;
an electrode (<NUM>) having an expansion coefficient that is lower than an expansion coefficient of the core and being wound into a roll shape on the outer circumference of the core; and
a fixing part (<NUM>) fixing an end portion from which the electrode starts being wound around the core,
characterized by
a tape member (<NUM>, <NUM>) that fixes an intermediate portion (<NUM>) between a winding-start end portion (<NUM>) and a winding-finish end portion (<NUM>) of the electrode to the core, so as to regulate the axial movement of the electrode wound into the roll shape with respect to the core.