KR20120096091A - Copper foil for lithium-ion battery collector body - Google Patents

Abstract

The copper foil for lithium ion battery collectors with high plate | board thickness precision is provided. The average Ra _avg of the surface roughness Ra in the rolling parallel direction is 0.01? 0.15 μm, ΔRa = Ra _max -Ra _min It is 0.025 micrometer or less, Copper foil for lithium ion battery collectors characterized by the above-mentioned.

Description

Copper foil for lithium ion battery collector {COPPER FOIL FOR LITHIUM-ION BATTERY COLLECTOR BODY}

The present invention relates to a copper foil for a lithium ion battery current collector, and more particularly to a copper foil for a lithium ion secondary battery negative electrode current collector.

Lithium ion batteries have high energy density and relatively high voltage, and thus are widely used for small electronic devices such as laptops, video cameras, digital cameras, and mobile phones. In the future, it is also promising to be used as a power source for large devices such as electric vehicles and distributed home type power supplies in general households.

The electrode body of a lithium ion battery generally has a stack structure in which a positive electrode, a separator, and a negative electrode are wound several times or stacked. Generally, the positive electrode is composed of a positive electrode current collector formed of aluminum foil and a positive electrode active material made of a lithium composite oxide such as LiCoO ₂ , LiNiO _2, and LiMn ₂ O ₄ formed on the surface thereof, and the negative electrode is a negative electrode collector formed of copper foil. It consists of the negative electrode active material which uses the whole etc. and carbon apply | coated to the surface.

As an important problem of copper foil used as a negative electrode current collector, there is adhesiveness with a negative electrode active material, and conventionally, research and development of the copper foil for electrical power collectors was made centering around improving this adhesiveness. As a general method for improving adhesiveness with an active material layer, the surface treatment which forms an unevenness | corrugation on the copper foil surface called a roughening process previously is mentioned. As the roughening treatment method, methods such as blasting, rolling with rough rolls, mechanical polishing, electropolishing, chemical polishing, and plating of electrodeposited grains are known. It is used a lot. This technique uses a copper sulfate acid plating bath to electrodeposit a large amount of copper on a copper foil surface in a resinous or globular shape to form fine irregularities, and aims to improve adhesion according to the anchoring effect. In order to prevent cracking due to concentration of stress in the recesses of the active material layer during expansion of the active material having a large volume change and concentration of stress at the current collector interface (for example, Japanese Patent Publication No. 3733067).

In Japanese Patent Publication No. 3733065, preferred surface properties are specifically specified by parameters of roughness, and the adhesion between the current collector and the active material is improved by using copper foil having a large value of surface roughness (Ra) as the current collector. It is described (paragraph 0209). The surface roughness Ra of the current collector is preferably 0.01 µm or more, more preferably 0.01? 1 µm, more preferably 0.05? 0.5 μm (paragraph 0021, etc.). It is described that it is preferable that the surface roughness Ra of an electrical power collector and the average spacing S of a local calculation have a relationship of 100 Ra≥S (paragraph 0022 etc.). It is described that the shape of the convex part of the unevenness | corrugation on the surface of an electrical power collector is preferably conical shape (paragraph 0023 etc.).

And such a surface form is obtained by depositing copper on the surface of electrolytic copper foil (paragraph 0044) and the rolled copper foil by electrolytic method, roughening the surface (paragraph 0045), and polishing with an emery paper (paragraph 0205). It is described.

: Japanese Patent Publication No. 3733067 : Japanese Patent Publication No. 3733065

Since the battery capacity of a lithium ion battery changes with the application amount of a negative electrode active material, control and management of the application amount of a negative electrode active material become important in order to stabilize | save battery characteristics, but management of the application amount in the application | coating process of a negative electrode active material, It is the present situation that it is performed by the weight which contained the copper foil after application | coating. Therefore, if the thickness of copper foil which is an electrical power collector is not fixed, the quantity of the negative electrode active material to apply | coat can not be managed suitably. Since the specific gravity of copper foil is about 8.92 g / cm <3>, and the specific gravity of carbon used as a negative electrode active material is about 0.5 g / cm <3>, the thickness of carbon corresponding to 0.1 micrometer of thickness of copper foil is 1.78 micrometers, for example. Therefore, when only 10 micrometers (1.00%) of thickness generate | occur | produce when a copper foil is manufactured and aimed at 10 micrometers in thickness, when it aims at 1.78 micrometers (thickness 40 micrometers), it corresponds to 4.45%. ) Or an error occurs. This corresponds to a variation of 4.45% in an active material having a thickness of 40 μm. That is, the slight variation in the thickness of the copper foil results in a great influence on the thickness of the active material. Therefore, the copper foil excellent in plate | board thickness precision is calculated | required.

However, in the past development direction of the copper foil for electrical power collectors, surface property control in the micro point which aimed at improving adhesiveness with a negative electrode active material was overwhelming. Therefore, the problem of improving the plate | board thickness precision of copper foil at a macro viewpoint, and aiming at the capacity stability of a lithium ion battery is an unsolved state.

Then, one object of this invention is to provide the copper foil for lithium ion battery collectors with high plate | board thickness precision. Moreover, this invention makes it one of the other subjects to provide the manufacturing method of such copper foil.

Copper foil is roughly divided into rolled copper foil and electrolytic copper foil. In rolled copper foil, plate | board thickness precision often arises from the function (ability) of a rolling mill, but in a rolling mill of the present situation, plate | board thickness precision is a limit of +/- 1.6% in 10 micrometers of target plate thickness. As a fundamental countermeasure, modification and development of a rolling mill are also desired, but since it requires a large amount of research and development costs, it is difficult to carry out immediately.

MEANS TO SOLVE THE PROBLEM In this situation, as a result of repeating research in order to solve the said subject, in the manufacturing process of a rolled copper foil, since most of rolling controls plate | board thickness by feedforward, about the plate thickness precision of a product, Note that the variation of the surface roughness before the final pass of the final cold rolling is one of the factors influencing the plate thickness control. It was found that the thickness precision was improved. Specifically, by using a work roll having a small surface roughness with respect to the rolling before the final pass, and using a work roll having a desired surface roughness in the final pass, a copper foil having a good plate thickness precision and a desired surface roughness is finally obtained. It could be obtained. The copper foil for the current collector requires a constant surface roughness because of its relation to adhesiveness with the active material, and the surface roughness is made as small as possible before the final pass of the final cold rolling, so that the desired surface roughness can be increased while increasing the plate thickness precision. You can have it.

In one aspect of the present invention, completed on the basis of the above findings, the average Ra _avg of the surface roughness Ra in the rolling parallel direction is 0.01? 0.15 μm, ΔRa = Ra _{m ax} -Ra _min It is 0.025 micrometer or less, It is copper foil for lithium ion battery collectors characterized by the above-mentioned.

In one Embodiment of the copper foil for lithium ion battery collectors which concerns on this invention, the plate | board thickness of copper foil is 5? 20 μm.

In another embodiment of the copper foil for lithium ion battery collectors which concerns on this invention, the difference of the maximum value t _max of the plate | board thickness of copper foil, the average value t _avg of plate | board thickness, or the minimum value (t _min ) and plate | board thickness the value of the larger one of the difference between the average value (t _avg) of a ratio of the average value of panap (t _avg) 1.3% or less.

In one embodiment of the lithium ion battery current collector copper foil according to the present invention, the ratio of RSm ΔRSm = _max -RSm _min on average _(avg RSm) of the surface roughness (RSm) in the rolling parallel direction (ΔRSm / RSm _avg ) is 0.5 or less.

In another embodiment of the copper foil for lithium ion battery collectors which concerns on this invention, copper foil is for lithium ion secondary battery negative electrode collectors.

This invention is another one side. WHEREIN: It is the lithium ion battery provided with the copper foil which concerns on this invention as an electrical power collector.

In another aspect of the present invention, in the final cold rolling step, the surface roughness Ra of the work roll used in the final pass is 0.03 µm or more, and the surface of the work roll used in one pass immediately before the final pass. Roughness (Ra) is less than 0.03 micrometer, It is the manufacturing method of the copper foil for lithium ion battery collectors characterized by the above-mentioned.

Since the copper foil which concerns on this invention is excellent in plate | board thickness precision, since the error of the application amount of a negative electrode active material can be suppressed, the battery capacity of the mass-produced lithium ion battery can be stabilized.

The copper foil base material used in this invention is a rolled copper foil. &Quot; Copper foil &quot; includes a copper alloy foil. There is no restriction | limiting in particular as a material of copper foil, What is necessary is just to select suitably according to a use and a required characteristic. For example, although not limited thereto, Cu-Ni- which has added high-purity copper (copper-free copper, tough pitch copper, etc.), copper alloys containing Sn, Ag, Fe, In, Te, etc., Ni, Si, etc. Copper alloys, such as the Cu-Zr system and Cu-Cr-Zr system copper alloy which added Si type copper alloy, Cr, Zr, etc. are mentioned. A rolled copper foil is excellent in the point which is high in strength, can respond to the environment which a vibration generate | occur | produces, and is high in bending resistance.

The thickness of the copper foil is not particularly limited and may be appropriately selected depending on the required characteristics. Generally 1? Although it is 100 micrometers, when using it as an electrical power collector of a lithium ion secondary battery negative electrode, thinning a copper foil can obtain a battery with a higher capacity. In that respect, typically 2? 50 μm, more typically 5? It is about 20 micrometers.

Copper foil according to the present invention, the rolling average _(avg Ra) of the surface roughness (Ra) in the parallel direction and ΔRa Ra = _{max min} -Ra Prescribed by Ra is a value obtained by dividing the roughness curve from the center line, dividing the area obtained by the roughness curve and the center line by the reference length L, and is measured according to JIS B0601: 2001. In the present invention, the mean (Ra _avg ) of the surface roughness (Ra) is an average of any ten points, and in the present invention, ΔRa is Ra _max which is the maximum value among the measured ten points of Ra. And the minimum value of Ra _min . However, arbitrary ten points here does not mean ten points in the vicinity of each measurement point, but, for example, in the case of a coil shape, at least 150 mm intervals in the rolling direction, preferably depending on the obtained length. Preferably 10 points at 400 mm intervals, more preferably at least 1 m intervals. Ra in each measuring point is given by the average value which measured the vicinity of the measuring point 3 times. In addition, each measuring point shall be Ra of the width direction center. Moreover, when disassembling a battery, even if it is a sheet | seat of the multiple copper foil for negative electrodes superimposed, if the measurement interval of 150 mm or more can be ensured, the surface roughness can be measured with respect to the sheet.

The copper foil which concerns on this invention is 0.01? With respect to the average Ra _avg of the surface roughness Ra in the rolling parallel direction. It is characterized by satisfy | filling 0.15 micrometer. The condition of 0.01 μm ≦ Ra ≦ 0.15 μm is that if Ra is less than 0.01 μm, the surface is smooth and sufficient adhesion with the negative electrode active material is not obtained, while if it exceeds 0.15 μm, the degree of roughness is reduced by rolling before the final pass. This is because the variation occurs due to the rolling of the final pass, even if it is made small and the variation of the surface roughness is small. However, when it considers from the viewpoint that the appearance quality with few surface defects, such as surface scratches, can be made stable, Ra 0.03 micrometer or more is preferable, and 0.03 micrometer <= Ra <= 0.1 micrometer is the more preferable range.

ΔRa = Ra _max -Ra _min It is also characterized by satisfy | filling this 0.025 micrometer or less. ΔRa = Ra _max -Ra _min This condition of 0.025 micrometer or less is because when ΔRa of copper foil after final rolling which is a product is 0.025 micrometer or less, it can mean that ΔRa before the final pass of final rolling is 0.025 micrometer or less. When ΔRa before the final pass of the final rolling is 0.025 μm or less, the influence on the plate thickness control due to the variation (variation) of the surface roughness during the final pass of the final rolling is small, and thus, the plate thickness precision of the product. Is improved. When ΔRa exceeds 0.025 μm, ΔRa before the final pass of the final rolling often exceeds 0.25 μm, and in that case, the roughness of the point where the surface roughness is large and where the surface roughness is small is less than that of the final rolling. The influence on the sheet thickness control of the final pass is different, and as a result, the variation of the final rolled sheet thickness in the strip becomes large. ΔRa is preferably 0.025 μm or less, and more preferably 0.020 μm or less.

On the other hand, in the rolled copper foil, in addition to the surface roughness determined by the roll mark, there exist a large number of depressions on the surface of the rolled copper foil called oil pits. The oil pit is a recess formed by the rolled oil being pushed into the rolled material, and the density of the oil pit on the surface varies according to the thickness of the oil film of the rolled oil. If the density of the oil pits on the surface is different, it also affects the sheet thickness of the copper foil obtained by the gravimetric method and becomes a factor of the variation. Therefore, it is preferable that the oil pit is uniformly distributed on the copper foil surface.

The amount of oil pits generated may have the surface roughness RSm in the rolling parallel direction as an index. When RSm is large, the oil pit on the surface is small and when RSm is small, the amount of oil pit is large. It is the ratio of ΔRSm = RSm _max -RSm _min to the mean (RSm _avg ) of the surface roughness (RSm) in the rolling parallel direction because it is the variation of the distribution of the oil pits that affects the plate thickness precision. ΔRSm / RSm _avg ) was used as an index. ΔRSm / RSm _avg The smaller is, the more uniformly distributed the oil pit is on the copper foil surface. The reason for dividing by RSm _avg is that the variation is not necessarily large because ΔRSm is large. That is, even if the same ΔRSm, RSm _avg If is large, the effect of the distribution is small because it is not large. RSm _avg If is small, the effect is large because of the large size of the distribution.

By increasing the rolling speed rapidly, increasing the viscosity of the rolled oil, or decreasing the rolling reduction per pass, the amount of oil pits generated increases and RSm tends to be smaller. On the contrary, by slowing the rolling speed, lowering the viscosity of the rolling oil, or increasing the reduction ratio per one pass, the amount of oil pits is reduced, and RSm tends to be large.

RSm is the average value of the interval of the mountain valley-period calculated | required from the intersection which a roughness curve cross | intersects an average line, and is measured based on JISB0601: 2001. In the present invention, the average roughness (RSm _avg ) of the surface roughness (RSm) is an average of any ten points, and ΔRSm is the maximum RSm _max among the measured ten points of Ra. And the minimum RSm _min . However, arbitrary ten points here does not mean ten points in the vicinity of each measurement point, but, for example, in the case of a coil shape, at least 150 mm intervals in the rolling direction, preferably depending on the obtained length. Preferably 10 points at 400 mm intervals, more preferably at least 1 m intervals. RSm in each measuring point is given by the average value which measured the vicinity of the measuring point 3 times. Further, each measurement point is set as RSm at the center in the width direction. Moreover, when disassembling a battery, even if it is a sheet | seat of the multiple copper foil for negative electrodes superimposed, if the measurement interval of 150 mm or more can be ensured, the surface roughness can be measured with respect to the sheet.

In one preferable embodiment of the copper foil which concerns on this invention, (DELTA) RSm / RSm _avg is 0.5 or less.

In one preferred embodiment of the copper foil according to the present invention, the difference between the maximum value t _max of the plate thickness and the average value t _avg of the plate thickness, or the minimum value t _min and the average value t _avg of the plate thickness. The ratio with respect to the average value t _{avg of} plate | board pressure of any one of the difference of the can be made into 1.3% or less. Preferably this ratio may be 1.2% or less, More preferably, it may be 1.1% or less.

Next, a method of manufacturing a copper foil according to the present invention will be described. Control of surface roughness Ra can be performed by adjustment of the surface roughness of a work roll, for example, when Ra uses a large work roll, Ra of the rolled copper foil obtained will become large, On the contrary, Ra is a small work piece. When a roll is used, Ra of the rolled copper foil obtained also becomes small. On the other hand, in general, the larger the average value of the deviation value itself is. Similarly, the larger the average value of the surface roughness Ra is, the larger the value of the deviation is. Therefore, in order to reduce the value of the variation of the surface roughness Ra, the surface roughness is reduced. What is necessary is just to reduce the average value of FIG.

However, in each product, since there is a request for the surface roughness required from the viewpoint of adhesion to the negative electrode active material and the like, it is necessary to finally make it a required value. Moreover, in cold rolling, it is more preferable that the surface roughness is rough to some extent from the viewpoint of the rolling efficiency that a rolling rate can be set high.

So, for example, using a work roll with a small surface roughness only for one pass immediately before the final pass of the final cold rolling, a copper foil having a low surface roughness, that is, a smooth surface is produced, and the surface roughness at the final pass Large work rolls are used to produce the desired surface roughness (Ra).

Thereby, copper foil with favorable adhesiveness with an active material can be obtained, having desired surface roughness, obtaining high thickness precision. In other words, the roll having rough surface roughness Ra may be sufficient until two passes of the final pass, and only one pass immediately before the final pass uses a roll having a roughness smaller than that of the previous pass and the last pass.

A work roll with a small surface roughness may be used for not only one pass immediately before the final pass but also a pass before the final pass. However, a roll having a small surface roughness cannot increase the rolling speed, which is not preferable in terms of productivity. Therefore, only the work roll used for the pass just before a last pass makes surface roughness small. However, disregarding the productivity point of view, a roll having a smaller surface roughness also has a higher effect of reducing the variation in surface roughness than the one pass immediately before the final pass. For example, even if it is a roll with small surface roughness only in 2 passes immediately before a final pass, it is effective.

In the final pass, the average Ra _avg in the rolling parallel direction of the copper foil was 0.01? Since the work roll uses the surface roughness Ra exceeding 0.01 micrometer so that it may become 0.15 micrometer, in order to make the value of the deviation of surface roughness small, The surface roughness Ra should be smaller than the work roll used for the final pass. Therefore, the surface roughness Ra of the work roll used in one pass immediately before the final pass is preferably 0.01 μm or less.

However, stably producing a roll having a surface roughness Ra of 0.01 µm or less and having no appearance problems such as surface scratches requires high technology and becomes relatively expensive in terms of cost.

Therefore, as for the more preferable range, it is preferable that the surface roughness Ra of the work roll used in a last pass is 0.03 micrometer or more, Therefore, the surface roughness Ra of the work roll used for 1 pass immediately before a final pass is It is preferable to make it less than 0.03 micrometer.

In order to reduce the variation of the surface roughness RSm, it is important to make the distribution of oil pits uniform. To even out the distribution of oil pits. Among several factors, it is important to keep the viscosity of the rolled oil constant during rolling. The viscosity of the rolled oil is basically determined depending on the type of the rolled oil, but the viscosity decreases as the rolled oil gradually rises due to the heat of processing during rolling. As the viscosity of the rolled oil changes, the degree to which the rolled oil is pushed onto the surface of the copper foil changes, which leads to variations in the oil pit distribution.

For example, when the rolling oil is maintained at around 25 ° C. in the temperature adjustment before rolling, when the rolling oil is sprayed onto the work roll during rolling, heat from the work roll raised by the processing heat is transferred, and the rolling oil is 40 ° C. Rises to a degree. If it can hold | maintain in this state, the dispersion | variation in the distribution of an oil pit is small and there is no problem in copper foil shape. However, when temperature control of a rolling oil is not enough, and a rolling oil temperature exceeds 40 degreeC and a deviation arises, not only the surface property of copper foil is easy to produce a deviation, but also affects plate shape. Therefore, in order to adjust the temperature of the rolling oil in rolling about 40 degreeC, it is necessary to comprehensively adjust the rolling oil temperature, rolling speed, workability, etc. before roll injection.

A lithium ion battery can be produced by usual means using the negative electrode comprised by the electrical power collector which uses the rolled copper foil which concerns on this invention as a material, and the active material layer formed on it. Lithium ion batteries include lithium ion primary batteries and lithium ion secondary batteries in which lithium ions in the electrolyte are responsible for electric conduction. Examples of the negative electrode active material include, but are not limited to, tin oxide and indium tin in which carbon, silicon, tin, germanium, lead, antimony, aluminum, indium, lithium, tin oxide, lithium titanate, lithium nitride, and indium are dissolved Alloys, lithium-aluminum alloys, lithium-indium alloys, and the like.

Example

Examples of the present invention are shown below, which are provided to better understand the present invention and are not intended to limit the present invention.

<Example 1 (Influence of Variation of Surface Roughness Ra)>

[Production of rolled copper foil]

After hot-rolling a tough pitch copper ingot, the annealing and cold rolling were repeated, and finally cold rolling was performed to obtain a rolled copper foil (No. 1 to 6) having a rolling direction length of 10 m or more and a set thickness of 10 μm. . In final cold rolling, Table 1 shows the surface roughness of the work roll used in only one pass immediately before the final pass and the surface roughness of the work roll used in the final pass. The viscosity of the rolled oil used was 7.0 cSt (40 degreeC), and the temperature of the rolled oil in final cold rolling was controlled about 40 degreeC. The surface roughness of the work roll was measured by a contact surface roughness measuring instrument according to JIS B0601: 2001.

The obtained rolled copper foil was mounted on a glass plate and fixed, and Ra _avg , (DELTA) Ra, RSm _{avg, and (} DELTA) RSm were computed based on the measuring method mentioned above using Confocal Microscope HD100D by Lasertec. The results are shown in Table 1.

[Plate thickness precision evaluation]

The plate thickness of the rolled copper foil was measured based on the gravimetric method (IPC-TM-650). The rolling direction length of arbitrary 10 m was selected from the obtained copper foil, and about this, 10 points of plate | board thicknesses were measured by 1 m space. The plate thickness T of each measuring point took the average value measured 3 times. The average value of T at 10 points was made T _avg , the maximum value of T at 10 points was T _max , and the minimum value of T at 10 points was T _min . In Table 1, the larger (T _avg -T _min ) / T _avg and (T _max -T _avg ) / T _avg was described as "plate thickness deviation (%)".

No.1? No. 4 was an invention example, and the variation in plate thickness could be suppressed to 1.3% or less.

Since No. 5 had a large surface roughness of one pass immediately before the final pass, ΔRa could not be sufficiently controlled. Instead of increasing the surface roughness of the work roll of one pass immediately before the last pass, No. 6 reduced the surface roughness of the work roll of the last pass, but still could not sufficiently control ΔRa.

&Lt; Example 2 (Influence of oil pit distribution) &gt;

[Production of rolled copper foil]

After hot rolling a tough pitch copper ingot, the annealing and cold rolling were repeated, and finally cold rolling was performed to obtain a rolled copper foil (No. 7 to 12) having a rolling direction length of 10 m or more and a set thickness of 10 μm. . In final cold rolling, the surface roughness (Ra) of the work roll used before the final pass was 0.010 micrometer and the work roll surface roughness (Ra) used for the last pass was 0.050 micrometer. The viscosity of the rolled oil used was 7.0 cSt (40 degreeC), and the invention example adjusted the temperature of the rolled oil in final cold rolling so that it might be around 40 degreeC. Various properties were evaluated in the same manner as in Example 1. The test results are shown in Table 2.

Invention Example No. 7? Since the temperature control of the rolling oil of the last rolling mill was controlled at 40 degreeC, distribution of the oil pits became uniform, the variation was small, and the variation of the plate | board thickness was small as less than 1.2%.

Invention Example No. 10? 12 is invention example No. 7? Other than temperature control of the rolling oil in a final cold rolling mill. It carried out under the same conditions as 9. Since temperature control of the rolled oil in the last cold rolling mill could not fully be performed here, it rose to about 45 degreeC exceeding 40 degreeC. Although it cannot confirm by a measurement, it is assumed that there existed a part exceeding 50 degreeC locally. As a result, the distribution of the oil pits could not be made uniform, and the variation in sheet thickness exceeded 1.2%.

Claims (7)

The average Ra _avg of the surface roughness Ra in the rolling parallel direction is 0.01? 0.15 μm, ΔRa = Ra _max -Ra _min It is 0.025 micrometer or less, Copper foil for lithium ion battery collectors characterized by the above-mentioned. The method of claim 1,
The thickness of the copper foil is 5? It is 20 micrometers, Copper foil for lithium ion battery collectors. The method according to claim 1 or 2,
The difference between the maximum value (t _max ) and the average value (t _avg ) of the plate thickness of the copper foil, or the difference between the minimum value (t _min ) and the average value (t _avg ) of the plate thickness. The ratio with respect to average value t _avg is 1.3% or less, Copper foil for lithium ion battery collectors characterized by the above-mentioned. The method according to any one of claims 1 to 3,
The ratio (ΔRSm / RSm _avg ) of ΔRSm = RSm _max- RSm _min to the average (RSm _avg ) of the surface roughness (RSm) in the rolling parallel direction is 0.5 or less, characterized in that the copper foil for a lithium ion battery current collector. The method according to any one of claims 1 to 4,
Copper foil for lithium ion battery collectors for lithium ion secondary battery negative electrode collectors. The lithium ion battery provided with the copper foil in any one of Claims 1-5 as an electrical power collector. In the final cold rolling step, the surface roughness Ra of the work roll used for the final pass is 0.03 µm or more, and the surface roughness Ra of the work roll used in one pass immediately before the final pass is less than 0.03 µm. The manufacturing method of the copper foil for lithium ion battery collectors characterized by the above-mentioned.