KR20140023955A - Lithium ion secondary cell, current collector constituting negative electrode of secondary cell, and electrolytic copper foil constituting negative-electrode current collector - Google Patents

Abstract

The electrolytic copper foil having the same coating properties of the active material slurry, high battery capacity, little battery capacity deterioration even after repeated charge / discharge cycles, and the active material coating layer is not peeled from the copper foil serving as the negative electrode current collector. It is providing, the lithium ion secondary battery which made the said electrolytic copper foil an electrical power collector, made the negative electrode which deposited the active material on the said electrical power collector, and put the said negative electrode.
It is an electrolytic copper foil which comprises the negative electrode collector of a lithium ion secondary battery, Both surfaces of the said electrolytic copper foil are formed by electrolytic precipitation, and the said electrolytic precipitation surface is electrolytic copper foil which is a crystal structure of a grain shape crystal | crystallization. Moreover, in the electrical power collector which consists of an electrolytic copper foil which comprises the negative electrode of a lithium ion secondary battery, both surfaces of the said electrolytic copper foil are formed by electrolytic precipitation, and the said electrolytic precipitation surface is comprised by the crystal structure of a grain shape crystal | crystallization.

Description

Lithium ion secondary battery, a current collector constituting the negative electrode of the secondary battery, and an electrolytic copper foil constituting the negative electrode current collector NEGATIVE-ELECTRODE CURRENT COLLECTOR}

The present invention provides a lithium ion secondary battery having a positive electrode, a negative electrode having a negative electrode active material layer formed on a surface of the negative electrode current collector, and a nonaqueous electrolyte, a current collector constituting the negative electrode of the secondary battery, and the negative electrode current collector It relates to the electrolytic copper foil to comprise.

Lithium ion secondary batteries comprising a negative electrode and a nonaqueous electrolytic solution which are coated with carbon particles as a negative electrode active material layer on a surface of a negative electrode current collector made of a positive electrode and an electrolytic copper foil having smooth surfaces on both sides, and dried, and which have a nonaqueous electrolyte are presently used in mobile phones. It is used for notebook type PC. As the negative electrode current collector of this lithium ion secondary battery, one which has been subjected to rust prevention treatment on so-called "untreated copper foil" produced by electrolysis is used.

As disclosed in Patent Literature 1, the copper foil as the negative electrode current collector for a lithium ion secondary battery uses an electrolytic copper foil that has smoothed the rough surface and further reduced the difference in the surface roughness between the glossy surface and the rough surface (both sides of the copper foil). It is possible to suppress the decrease in the charge and discharge efficiency of the battery.

The electrolytic copper foil which smoothed the rough surface mentioned above and made the difference of the surface roughness between a gloss surface and a rough surface, suitably contains various water-soluble high molecular substance, various surfactant, various organic sulfur type compounds, chloride ion etc. in copper sulfate-sulfuric acid electrolyte solution. It manufactures by electrolytically depositing copper to a rotating titanium drum negative electrode using the electrolyte solution selected and added, and peeling and winding this when it becomes predetermined thickness.

For example, a technique for producing an electrolytic copper foil has been proposed by adding a compound having a mercapto group, a chloride ion, and a low molecular weight glue and a high molecular weight polysaccharide having a molecular weight of 10,000 or less to a copper sulfate-sulfuric acid electrolyte solution (see Patent Document 1).

This electrolytic copper foil is 300-350 N / mm <^2> in tensile strength, and when using it as an electrical power collector (copper foil) for negative electrodes which used the said carbon particle as an active material, it is a suitable material with suitable elongation.

Furthermore, an electrolytic copper foil having a rough roughness of the rough surface has been proposed, and for lithium ion secondary batteries using a carbon-based active material which is the mainstream, the roughness of this type is smooth, and the difference in the surface roughness between the polished surface and the roughness is Small copper foil is mainly used (refer patent document 2, patent document 3).

However, in recent years, for the purpose of increasing the capacity of a lithium ion secondary battery, a lithium ion secondary battery using an alloy active material electrochemically alloyed with lithium during charging, for example, aluminum, silicon, tin, or the like as a negative electrode active material It is proposed (refer patent document 4).

A negative electrode for a lithium ion secondary battery for the purpose of high capacity is formed by depositing silicon as an amorphous silicon thin film or a microcrystalline silicon thin film on a current collector such as copper foil by CVD or sputtering. Since the thin film layer of the active material produced by such a method is in close contact with the current collector, it has been found to exhibit good charge and discharge cycle characteristics (see Patent Document 5).

Moreover, in recent years, the formation method which apply | coats a powder silicon or a silicone compound to the copper foil in the shape of a slurry with an imide-type binder with an organic solvent, and is dried and pressed is also developed. (Refer patent document 6)

Even if the type of the negative electrode active material is carbon or alloy type, there is a demand for a copper foil having high battery capacity, little battery capacity deterioration even after repeated charge and discharge cycles, and the active material thin film layer is not peeled from the copper foil serving as the negative electrode current collector. .

Patent Document 1: Japanese Patent No. 3742144 Patent Document 2: Japanese Unexamined Patent Publication No. 2004-263289 Patent Document 3: Japanese Unexamined Patent Publication No. 2004-162144 Patent Document 4: Japanese Patent Application Laid-Open No. 10-255768 Patent Document 5: Japanese Unexamined Patent Publication No. 2002-083594 Patent Document 6: Japanese Unexamined Patent Publication No. 2007-227328

The present invention has excellent applicability of the active material slurry, high battery capacity, little deterioration of battery capacity even after repeated charge and discharge cycles, and electrolysis of the same degree on both sides in which the active material coating layer is not peeled from copper foil which is a negative electrode current collector. It is a subject to provide a lithium ion secondary battery which provides a copper foil, uses the said electrolytic copper foil as an electrical power collector, makes it the negative electrode which deposited the active material on the said electrical power collector, and put the said negative electrode.

The lithium ion secondary battery of this invention is a lithium ion secondary battery provided with a positive electrode, the negative electrode by which an electrode structure active material layer is formed on the surface of an electrical power collector, and a nonaqueous electrolyte solution, and comprises the negative electrode of the said lithium ion secondary battery. The said collector consists of electrolytic copper foil, both surfaces of the said electrolytic copper foil are formed by electrolytic precipitation, and the said electrolytic precipitation surface is crystal structure of a grain shape crystal | crystallization.

The current collector for lithium ion secondary batteries of the present invention is a current collector constituting the positive electrode, the negative electrode formed with an electrode constituent active material layer on the surface of the current collector, and the negative electrode of a lithium ion secondary battery having a nonaqueous electrolyte solution, The said electrical power collector consists of an electrolytic copper foil, the both surfaces of the said electrolytic copper foil are formed by electrolytic precipitation, and the said electrolytic precipitation surface is crystal structure of a grain shape crystal | crystallization.

The electrolytic copper foil for lithium ion secondary battery negative electrode collector of this invention is the electrolytic copper foil which comprises the said negative electrode collector of the lithium ion secondary battery provided with a positive electrode, a negative electrode, and a nonaqueous electrolyte solution, and both surfaces of the said electrolytic copper foil are electrolytic precipitation furnaces. The electrolytic precipitation surface is formed, and the crystal structure of the grain shape crystal is formed.

The lithium ion secondary battery of the present invention is a lithium ion secondary battery having a negative electrode having an electrode constituent active material layer formed on a surface of a positive electrode and a current collector, and a nonaqueous electrolyte, and the current collector constituting the negative electrode is made of copper. It is an electrolytic copper foil formed by electrolytic precipitation, The 1st surface of the said electrolytic copper foil is a surface formed with the coin crystal of the crystal structure of grain shape on the drum surface, The 2nd surface on the opposite side to the said 1st surface is a 1st surface It is the surface formed after the film forming by the coin stone of the crystal structure of a grain shape on the back side of a 1st surface.

The negative electrode current collector for a lithium ion secondary battery of the present invention comprises a positive electrode, a negative electrode formed with an electrode constituent active material layer on the surface of the current collector, and a negative electrode constituting the secondary battery of a lithium ion secondary battery having a nonaqueous electrolyte. It is an electrical power collector, The said negative electrode electrical power collector is an electrolytic copper foil formed by electrolytically depositing copper, The 1st surface of the said electrolytic copper foil is the surface formed by the coin crystal of the crystal structure of grain shape on the drum surface, The said 1st surface The second surface on the opposite side is a surface formed of coin crystals of crystalline structure of grain shape on the back side of the first surface after the first surface film formation.

The electrolytic copper foil for lithium ion secondary battery negative electrode collectors of this invention is the electrolytic copper foil for negative electrode collectors which comprise the said secondary battery of the lithium ion secondary battery provided with a positive electrode, a negative electrode, and a nonaqueous electrolyte solution, The said electrolytic copper foil is copper It is an electrolytic copper foil which electrolytically precipitates and forms, The 1st surface of the said electrolytic copper foil is a surface formed with the coin stone of the crystal structure of grain shape on the drum surface, The 2nd surface on the opposite side to the said 1st surface is a 1st surface It is the surface formed after the film formation by the coin stone of the crystal structure of a grain shape on the back side of a 1st surface.

The present invention has excellent applicability of the active material slurry, high battery capacity, little deterioration of battery capacity even after repeated charge / discharge cycles, and electrolysis of the same level on both sides where the active material coating layer is not peeled from the copper foil serving as the negative electrode current collector. Copper foil can be provided.

Moreover, this invention uses the said electrolytic copper foil as an electrical power collector, and accumulates an active material in the said electrical power collector, making it a negative electrode, and setting it as the lithium ion secondary battery which inserted the said negative electrode. A current collector that does not peel off can be provided, and by constructing the negative electrode with the current collector, a lithium ion secondary battery having a high battery capacity and low deterioration of the battery capacity can be provided even if the charge / discharge cycle is repeated. .

1: is explanatory drawing which shows one Example of the process of manufacturing the electrolytic copper foil with the shape of both surfaces,
2 is an explanatory diagram of a device for manufacturing a conventional electrolytic copper foil,
3 shows a first embodiment of the electrolytic copper foil of the present invention, A1 is a micrograph (SEM) showing an electrolytic precipitation surface first formed, A2 is an electrolytic precipitation surface formed next,
4 shows a second embodiment of the electrolytic copper foil of the present invention, A1 is a micrograph (SEM) showing an electrolytic precipitation surface first formed, and A2 is an electrolytic precipitation surface formed next,
5 shows a third example of the electrolytic copper foil of the present invention, A1 is a micrograph (SEM) showing an electrolytic precipitation surface formed first, and A2 is an electrolytic deposition surface formed next,
6 shows a fourth embodiment of the electrolytic copper foil of the present invention, A1 is a micrograph (SEM) showing an electrolytic precipitation surface formed first, and A2 is an electrolytic precipitation surface formed next,
7 is a micrograph (SEM) of a conventional electrolytic copper foil, where X1 represents a drum surface and Y1 represents a drum surface.

In this specification, the surface which contacted the electrolyte solution of electrolytic copper foil is described with "electrolytic precipitation surface."

Electrolytic copper foil of this invention is "electrolytic precipitation surface of both surfaces of the 1st surface and the 2nd surface on the opposite side to a 1st surface". Both surfaces of the copper foil are composed of the surfaces that were in contact with the electrolytic solution so that both surfaces of the copper foil can be pulverized by, for example, the pulverizing apparatus shown in FIG. 1 described later.

The electrolytic copper foil is generally arranged with a rotating titanium drum 21 and an insoluble anode (22, hereinafter referred to as DSA), as shown in Fig. 2, and the titanium drum 21 and the DSA ( The copper foil 24 is manufactured by flowing the electrolyte solution of copper sulfate-sulfuric acid between 22), making a titanium drum 21 into a cathode, and passing a current between titanium drum-DSA as a DSA 22 as an anode.

When a current flows between the titanium drum 21 and the DSA 22, copper is electrolytically deposited on the titanium drum 21. When this thickness reaches a predetermined thickness, the electrolytic copper foil 24 is manufactured by continuously pulling off and winding. Usually, foil of this state is called "untreated copper foil."

The electrolytic copper foil 24 manufactured by the manufacturing method shown in FIG. 2 differs in shape from the surface 241 in contact with the electrolyte solution 23 and the surface 242 in contact with the titanium drum 21.

The surface 241 which contacted the electrolyte solution 23 normally is called "rough surface", and the surface 242 which contacted the titanium drum 21 is called "glossy surface."

However, in the case of the electrolytic copper foil for the negative electrode collector of a lithium ion secondary battery, as shown to the said patent documents 1-3, the surface which contact | connected electrolyte solution produced rather smooth electrolytic copper foil rather than the surface which contacted the titanium drum. As it is possible, in the copper foil industry for lithium ion secondary batteries, the surface 241 which contacted the electrolyte solution was called "electrolytic precipitation surface" or "electric stone surface", and the surface 242 which contacted the titanium drum is called "drum surface." have. In this specification, the "electrolytic precipitation surface" and the "drum surface" which are common in the copper foil industry for lithium ion secondary batteries are employ | adopted, and the surface which contacted the electrolyte solution of the electrolytic copper foil is expressed as "electrolytic precipitation surface" as mentioned above. .

The “drum face” that is in contact with the titanium drum is glossy in the eye and appears to be a smooth surface at first glance, but when observed with SEM, it is stripe-shaped in the MD direction (vertical direction) of the foil, as shown in Fig. 7 (Y1). There is irregularities.

On the other hand, in the "electrolytic precipitation surface" shown in FIGS. 3-6, a stripe-shaped unevenness | corrugation is not seen but is a surface smoother than a "drum surface."

This is because "drum surface" is the surface which contacted the titanium drum. After the surface of the titanium drum is polished, the titanium drum is set in an electrolytic cell 26 as shown in FIG. 2 to manufacture copper foil.

At this time, in order to use the electrolytic solution of copper sulfate-sulfuric acid at a relatively high temperature around 50 ° C, the surface of the titanium drum 21 gradually becomes rough while the production of the copper foil 24 becomes difficult to peel off. In order to avoid this, after producing copper foil for a certain period of time, the titanium drum surface is polished regularly, and the production is continued again.

Usually, the surface of a titanium drum is performed by the cylindrical abrasive buffing which carried out uniform adhesion impregnation of abrasive grains, such as aluminum oxide and a silicon carbide, on a nylon nonwoven fabric.

The "drum surface" becomes a replica of the "grinding string" of the titanium drum which surface-polished by the buffing mentioned above.

Therefore, in the usual manufacturing method, it is inevitable that the stripe-shaped irregularities as shown in Fig. 7 (Y1) exist in the MD direction (vertical direction) of the "drum surface".

The copper foil shown in FIG. 7 has been used as a negative electrode current collector of a lithium ion secondary battery for consumer use such as a notebook PC, a mobile phone, etc., but the difference in the shape of the "drum surface" and the "electrolytic precipitation surface" is now No problem occurred until now.

For example, the difference in the coating property at the time of active material application | coating or the charge / discharge efficiency after becoming a battery did not have a problem in particular.

However, when an electrolytic copper foil is adopted for the negative electrode current collector of a lithium ion secondary battery for automobiles such as HEV, EV, and PHEV, a lithium ion secondary battery is used in the "drum surface" and the "electrolytic precipitation surface" of the electrolytic copper foil. The difference of the charge / discharge efficiency after it became a problem became a problem.

The cause of the problem is that when manufacturing a negative electrode of a lithium ion secondary battery, the negative electrode is manufactured by continuously running a current collector (copper foil), applying a slurry-like active material, and drying and winding, but speed of running the copper foil. It is considered that the case of the battery manufacturing for automobiles is much faster than the case of manufacturing the battery for public use.

In addition, for the charging and discharging efficiency, a certain level of efficiency is required even after the reduction of the charging and discharging efficiency has been used for about 10 years in the case of automobiles. As such, a much more stringent level of performance is required.

As mentioned above, when the charge / discharge efficiency after battery manufacture is compared with the `` drum surface '' and the `` electrolytic precipitation surface '' of the electrolytic copper foil by the strict evaluation criteria required for a lithium ion secondary battery for automobiles, the `` drum surface '' becomes `` Tends to be greater (faster) than in electrolytic precipitation surface ".

This phenomenon can be seen in the same manner as in a lithium ion secondary battery using an alloy-based active material, for example, aluminum, silicon, tin, or the like, as an anode active material, which is electrochemically alloyed with lithium during charging for the purpose of high capacity. .

The decrease in the charge / discharge efficiency of a lithium ion secondary battery using aluminum, silicon, tin, or the like as a negative electrode active material is remarkably less cycles than when using a carbon-based active material, for example, about 50 to 100 cycles.

Also in this case, when the "drum surface" and the "electrolytic precipitation surface" of an electrolytic copper foil are compared, it can be seen that the "drum surface" has a larger deterioration in charge and discharge efficiency than the "electrolytic precipitation surface" in terms of charge and discharge efficiency. .

Furthermore, the present inventors analyzed this phenomenon in detail, and discovered that the difference of the surface shape of a "drum surface" and an "electrolytic precipitation surface" is a big factor.

That is, it turned out that the stripe-shaped unevenness | corrugation of a "drum surface" is easy to cause deterioration by the point of charge / discharge efficiency. Although it is not clear about this cause, it is estimated that the contact area of a negative electrode active material and an electrolytic copper foil is because a contact area is larger in an "electrolytic precipitation surface" than a "drum surface."

In order to match the surface shape of a "drum surface" and an "electrolytic precipitation surface", this inventor etc. use the same electrolyte solution at the time of electrolytic copper foil manufacture as the "drum surface" of the copper foil after manufacture, and the stripe-shaped unevenness | corrugation of a "drum surface" The copper plating of the thickness which erases and performed the "drum surface" was also made into the same shape as the "electrolytic precipitation surface", and examined to set it as the negative electrode collector for lithium ion secondary batteries.

In addition, as another embodiment, in order to remove the striped irregularities of the "drum surface", if it is possible to obtain the same shape as the "electrolytic precipitation surface", it is also considered effective to use an electrolyte solution having a composition different from that of the electrolytic copper foil. It was.

The surface of the electrolytic copper foil for lithium ion secondary battery negative electrode collectors is suitable for the smooth and glossy surface. This is as showing in patent examples 1-3. In order to make the surface smooth and glossy suitable as a collector for such a lithium ion secondary battery, it is effective to make a copper crystal structure into grain shape crystal | crystallization.

The improved electrolytic copper foil for lithium ion secondary battery negative electrode collector which prevents deterioration of the charge / discharge efficiency of the present invention is formed by the above-mentioned pulverization process. The "drum surface (second surface)" side is the following process, and the granules of the granular crystal copper of the thickness which removes the stripe-shaped unevenness | corrugation formed in the previous process are performed, and both surfaces have the same particle shape crystal as the "electrolytic precipitation surface". As a surface shape which consists of these, it can finish with copper foil which is smooth and gloss.

An example of the specific manufacturing method of the said electrolytic copper foil is shown in FIG.

The copper foil 1 of the crystal structure of grain shape crystal | crystallization is manufactured in the 1st drum 11, and it is pulled off, and the particle shape crystal | grain of the drum surface 101 side of the copper foil 1 is pulled out with the 2nd drum 12. Coin stone of the crystal structure is buried, the polishing string of the titanium drum 11 is buried, and the drum surface 101 is used as the electrolytic precipitation surface 103, and the surface shape of both surfaces is the same as the electrolytic precipitation surface 102. do.

In this case, it is better to make the electrolyte solutions 13 and 18 of the first electrolytic cell 16 and the second electrolytic cell 17 the same electrolytic solution. However, in the first electrolytic cell 16 and the second electrolytic cell 17, the liquid is good. Even if electrolyte compositions with different compositions are used, the surface shapes of both surfaces can be made the same.

The coin drum of the crystal structure of the grain-shaped crystal is performed with the first drum 11, and the coin stone of the grain-shaped crystal is formed in the second drum 12 even if a coin solution different in composition from the first electrolytic cell 16 is used. By carrying out, it is possible to make the shape of both surfaces the same.

Moreover, in order to obtain the foil of the same shape on both surfaces, the manufacturing method is easy for the method which makes the thickness of the copper foil formed in the 1st drum and the thickness of the copper coating formed in the 2nd drum the same. However, it is also possible to make the thickness of the copper foil formed in the 1st drum thicker, and to make the thickness of the copper coating formed in the 2nd drum thin.

The former method is suitable for producing a thick foil of about 35 μm, while the latter is suitable for producing a thin foil of about 6 μm.

For example, it is substantially difficult to produce 3 μm copper foil in the first drum and to perform 3 μm copper cladding in the second drum. It is difficult to manufacture 3 micrometers copper foil in a 1st drum, and to carry out 3 micrometers of copper coatings in a 2nd drum, because foil is easy to be broken in a 1st drum.

On the other hand, by the latter method, for example, 5.0 μm of copper foil can be produced in the first drum, and 1.0 μm of copper foil can be coated in the second drum as long as the tensile strength of the copper foil produced in the first drum is sufficiently high. Do.

In addition, it is thought that 6-35 micrometers is suitable as thickness of the said manufacturing method.

Thus, when the active material slurry is apply | coated by obtaining foil of the same shape on both surfaces, the same wettability can be obtained, the conditions setting of an active material application process becomes easy, the coating film structure of both surfaces becomes the same, and charge / discharge of the same grade A characteristic can be acquired and it is thought that it exhibits extremely stable performance as a battery.

As described above, the present invention is a lithium ion secondary battery having a positive electrode and a negative electrode in which the electrode constituent active material layer is formed on the surface of the current collector, wherein the negative electrode current collector electrolytically precipitates copper having a grain-shaped crystal structure. The electrolytic copper foil which has a drum surface and an electrolytic precipitation surface is formed for the first time.

Subsequently, a coin stone of crystal structure of granular crystal is formed in the thickness which removes the stripe-shaped unevenness | corrugation formed in the drum surface in the previous process, and the copper layer used as an electrolytic precipitation surface is provided on the said electrolytic copper foil. The electrolytic copper foil thus produced is used as a negative electrode current collector, an active material is deposited on the negative electrode current collector to form a negative electrode, and the negative electrode is inserted into a lithium ion secondary battery.

In addition, the present invention is a lithium ion secondary battery having a positive electrode and a negative electrode in which an electrode constituent active material layer is formed on the surface of a planar current collector, wherein the negative electrode current collector electrolytically precipitates copper having a grain-shaped crystal structure. It forms the electrolytic copper foil which has "drum surface" and "electrolytic precipitation surface" for the first time.

Next, the copper foil which performed the coin stone of the crystal structure of a grain shape as described above on the "drum surface" of the said electrolytic copper foil is created. The negative electrode current collector was applied to at least one surface of the electrodeposited copper foil thus prepared by applying a surface treatment to improve adhesion to the electrode constituent active material layer, and the active material was deposited on the negative electrode current collector to form a negative electrode. It is set as a lithium ion secondary battery.

The foil is classified as "untreated foil" because no surface treatment is performed at all after milling. "Untreated foil" is an intermediate product without any surface treatment. To use this as a battery foil, some surface treatment must be applied.

Usually, surface treatment is performed for the purpose of improving adhesiveness with an electrode component active material layer with a rust prevention function.

The antirust treatment is an inorganic antirust treatment or an organic antirust treatment. As an inorganic antirust process, chromate treatment etc. are performed. Examples of the organic rust-preventing treatment include benzotriazole treatment, silane capping agent treatment, and the like.

For chromate treatment, an aqueous solution containing dichromate ions is used, and either acidic or alkaline may be used, and immersion treatment or cathodic electrolytic treatment is performed. In addition, in this chromate treatment, the adhesion form to copper foil is an oxide or hydroxide of trivalent chromium reduced from hexavalent chromium.

As a typical chemical agent, chromium trioxide, potassium dichromate, sodium dichromate and the like are used.

Benzotriazoles as organic rust-preventing treatments include benzotriazole, methylbenzotriazole, aminobenzotriazole, carboxy benzotriazole and the like, and are carried out by immersion treatment or spray treatment as an aqueous solution.

There are many kinds of the silane capping agent, such as those having an epoxy group, an amino group, a mercapto group, and a vinyl group. However, those having excellent adhesion to the electrode constituent active material layer may be used, and may be immersed or sprayed using an aqueous solution or solvent. Conduct.

By the above process, the copper foil for lithium ion secondary battery negative electrode collectors is completed.

(Example)

Although an Example demonstrates this invention further in detail below, these do not limit this invention.

&Lt; Example 1 &gt;

The electrolytic copper foil was milled by the apparatus shown in FIG. That is, copper sulfate having the following composition between the titanium drum 11 and the DSA 14 by the first electrolytic cell 16 having the rotating titanium drum 11 as a cathode and having the DSA 14 disposed thereunder. -An electrolytic copper foil 1 having a thickness of 6 μm was produced by flowing an electrolyte solution 13 of sulfuric acid and a current flowing between the titanium drum and DSA.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Hydroxyethyl cellulose = 1-30 ppm

Low molecular weight gelatin (molecular weight 3,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

Roughness of the electrolytically deposited surface 102 of this copper foil 1 was Rz = 1.3 micrometer, Ra = 0.3 micrometer, and the roughness of the drum surface 101 was Rz = 1.6 micrometer, Ra = 0.4 micrometer.

The copper foil 1 was guided to the second drum 12, and a 6 µm coin was performed on the drum surface side using the same electrolyte solution 18 as the first electrolyte solution, thereby obtaining 12 µm foil (2). The roughness of the surface of the drum 101 on the surface of the coin 101 was Rz = 1.3 µm and Ra = 0.3 µm, and both surfaces of the copper foil 2 having the shape of "electrolytic precipitation surface" were obtained. This copper foil had a tensile strength of 310 MPa and an elongation of 8.0%.

In addition, Rz is a 10-point average roughness of JISBB0601-1994, and Ra is an arithmetic mean roughness of JISBB0601-1994.

Next, this copper foil was subjected to negative electrode electrolysis for 0.3 A / dm ² for 10 seconds in a 5 g / L solution of chromium trioxide, washed with water and dried to obtain an electrolytic copper foil for batteries.

Moreover, the electron microscope photograph of this electrolytic copper foil was taken, and the electrolytic precipitation surface by a 1st drum was shown in FIG. 3 (A1), and the copper was electrolytically precipitated by the 2nd drum on the drum surface of a 1st drum in FIG. 3 (A2). Side is shown.

It turns out that both surfaces of copper foil have the shape of an "electrolytic precipitation surface."

In addition, the silicon type particle | grains of average particle diameter were used for the active material.

To 74% of the active material, 16% of acetylene black powder (AB), 5% of styrene butadiene copolymer (SBR) and 5% of carboxymethyl cellulose sodium (CMCNa) were mixed with water as a solvent to prepare a slurry. Then, the slurry is applied to the electrolytic copper foil, the coating film is made into an almost uniform sheet, dried, compressed with a press, and the active material layer is closely bonded to the current collector, and further reduced pressure is dried to test electrode (cathode). Was produced. After that, a hole was punched out to 20 phi to form a cathode.

1.3 mol of LiPF ₆ / ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + dimethyl carbonate (DMC) (EC: EMC: DMC = 2: 5: 3 (volume ratio)) A tripolar cell was produced as an electrolyte solution.

Evaluation of the negative electrode in this test cell was performed at the temperature of 25 degreeC by the following method.

Charging / discharging test method;

Crate output

The C rate was calculated as follows based on the amount of active material in the test electrode.

Si ： 1C = 4,000mAh / g

First condition

Charging: After carrying out constant current charging with 0.1C equivalency electric current, reaching 0.02V (large Li / Li +), it was charged with an electric potential, and was complete | finished when the charging current fell to 0.05C equivalent.

Discharge: The constant current was discharged at a current equivalent to 0.1 C, and was terminated when it reached 1.5V.

Charge / discharge cycle condition

After the first charge and discharge test, charge and discharge were repeated up to 100 cycles with the same 0.1C equivalent current.

Table 1 shows discharge capacity retention rates after 10 cycles, 50 cycles, and 100 cycles of charge and discharge for the electrode using this electrolytic copper foil as the negative electrode current collector material.

In addition, the discharge capacity maintenance support ratio after a cycle is shown by following Formula.

(% Discharge capacity retention holding ratio after each cycle) = [(discharge capacity after each cycle) / (maximum discharge capacity)] × 100

House Active material coated surface
Active material coating surface roughness  Charging / discharging efficiency (%) Ra (μm) Rz (μm) After 10 cycles After 50 cycles After 100 cycles Example 1 A1 Electrolytic precipitation surface 0.3 1.3 84 48 39 A2 Noodles deposited on the drum surface 0.3 1.3 84 48 39 Example 2 B1 Electrolytic precipitation surface 0.3 1.2 85 48 40 B2 Noodles deposited on the drum surface 0.3 1.5 84 46 38 Example 3 C1 Electrolytic precipitation surface 0.3 1.2 85 48 40 C2 Noodles deposited on the drum surface 0.2 1.1 85 48 40 Example 4 D1 Electrolytic precipitation surface 0.3 1.2 86 49 41 D2 Noodles deposited on the drum surface 0.2 1.5 83 46 38 Comparative Example 1 X1 Drum face 0.4 1.6 76 36 23 Comparative Example 2 Y1 Drum face 0.4 1.8 72 33 20

&Lt; Example 2 &gt;

An 11-micrometer-thick electrolytic copper foil was produced by the first drum under the same conditions as in Example 1. This copper foil was guide | induced to the 2nd drum, 1 micrometer coin was performed on the drum surface side using the same electrolyte solution as a 1st drum, and 12 micrometers foil was obtained.

The roughness of the electrolytically deposited surface roughness of this copper foil was Rz = 1.2 µm, Ra = 0.3 µm, and the surface of the coin surface on the drum was Rz = 1.5 µm and Ra = 0.3 µm. Tensile strength of this copper foil is 310 MPa, and elongation is 9.0%.

Moreover, the electron microscope photograph of this electrolytic copper foil was taken, electrolytic precipitation of the electrolytic precipitation surface by a 1st drum in FIG. 4 (A1), and copper by the 2nd drum on the drum surface of a 1st drum in FIG. 4 (A2). The surface was shown.

Next, after wash | cleaning this copper foil in water, it carried out similarly to Example 1, cathodic electrolysis was performed both sides in the chromium trioxide solution, washed with water, and it dried and it was set as the electrolytic copper foil for battery collectors.

The active material similar to Example 1 was apply | coated to this electrolytic copper foil, and preparation and evaluation of the test cell were performed by the same method. The results are written together in Table 1.

&Lt; Example 3 &gt;

A rotating titanium drum is used as the cathode, and the first drum having the DSA disposed thereunder is used to flow an electrolyte solution of copper sulfate-sulfuric acid having the following composition between the titanium drum and the DSA, and a current flows between the titanium drum and the DSA, and is 11 μm thick. The electrolytic copper foil of was manufactured.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Hydroxyethyl cellulose = 1-30 ppm

Low molecular weight gelatin (average molecular weight 3,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

The electrolytic precipitation surface roughness of this copper foil was Rz = 1.2 µm, Ra = 0.3 µm, and the drum surface roughness was Rz = 1.4 µm and Ra = 0.4 µm.

This copper foil was guide | induced to the 2nd drum, 1 micrometer coin coin was performed to the drum surface side using the electrolyte solution different from a 1st drum as follows, and 12 micrometers foil was obtained. The roughness of the surface of the coin surface on the drum surface was obtained with copper foil in the shape of "electrolytic precipitation surface" on both surfaces of the roughness of Rz = 1.1 µm and Ra = 0.2. Tensile strength of this copper foil is 310 MPa, and elongation is 8.0%.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Polyethylene glycol (average molecular weight 1,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

Moreover, the electron microscope photograph of this electrolytic copper foil was taken, electrolytic precipitation of the electrolytic precipitation surface by a 1st drum in FIG. 5 (A1), and copper by the 2nd drum on the drum surface of a 1st drum in FIG. 5 (A2). The surface was shown.

Next, after wash | cleaning this copper foil in water, it carried out similarly to Example 1, cathodic electrolysis was performed both sides in the chromium trioxide solution, washed with water, and it dried and it was set as the battery electrolytic copper foil.

The active material similar to Example 1 was apply | coated to this electrolytic copper foil, and the test cell was produced and evaluated by the same method. The results are written together in Table 1.

<Example 4>

A rotating titanium drum is used as the cathode, and the first drum having the DSA disposed thereunder is used to flow an electrolyte solution of copper sulfate-sulfuric acid having the following composition between the titanium drum and the DSA, and a current flows between the titanium drum and the DSA, and is 11 μm thick. The electrolytic copper foil of was manufactured.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Polyethylene glycol (average molecular weight 1,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

The electrolytic precipitation surface roughness of this copper foil was Rz = 1.2 µm, Ra = 0.3 µm, and the drum surface roughness was Rz = 1.8 µm and Ra = 0.4 µm.

This copper foil was guided to the second drum, and 1 µm coin stone was performed on the drum surface side using the following electrolytic solution different from the first drum to obtain 12 µm foil. The roughness of the surface of which the coin stone was performed on the drum surface was able to obtain the copper foil which made the shape of "electrolytic precipitation surface" on both surfaces of Rz = 1.5 micrometer and Ra = 0.2 roughness. Tensile strength of this copper foil is 310 MPa, and elongation is 8.0%.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Hydroxyethyl cellulose = 1-30 ppm

Low molecular weight gelatin (average molecular weight 3,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

Moreover, the electron microscope photograph of this electrolytic copper foil was taken, electrolytic precipitation of the electrolytic precipitation surface by a 1st drum in FIG. 6 (A1), and copper by the 2nd drum on the drum surface of a 1st drum in FIG. 6 (A2). The surface was shown.

Next, after wash | cleaning this copper foil in water, it carried out similarly to Example 1, cathodic electrolysis was performed both sides in the chromium trioxide solution, washed with water, and it dried and it was set as the battery electrolytic copper foil.

The active material similar to Example 1 was apply | coated to this electrolytic copper foil, and preparation and evaluation of the test cell were performed by the same method. The results are written together in Table 1.

&Lt; Comparative Example 1 &

A rotating titanium drum is used as a cathode, and a drum having a DSA disposed thereunder, an electrolyte of copper sulfate-sulfuric acid having the following composition is flowed between the titanium drum and the DSA, and an electric current is flowed between the titanium drum and the DSA so as to flow a 12 μm thickness. Copper foil was manufactured.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Hydroxyethyl cellulose = 1-30 ppm

Low molecular weight gelatin (molecular weight 3,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

The electrolytic precipitation surface roughness of this copper foil was Rz = 1.3 µm, Ra = 0.3 µm, and the drum surface roughness was Rz = 1.6 µm and Ra = 0.4 µm.

The electron microscope photograph of this electrolytic copper foil was taken, and the drum surface was shown to FIG. 7 (X1).

Next, after wash | cleaning this copper foil in water, it carried out similarly to Example 1, cathodic electrolysis was performed both sides in the chromium trioxide solution, washed with water, and it dried and it was set as the battery electrolytic copper foil.

The active material similar to Example 1 was apply | coated to this electrolytic copper foil, and the test cell was produced and evaluated by the same method. The result was written together in Table 1.

&Lt; Comparative Example 2 &

A rotating titanium drum is used as a cathode, and a drum having a DSA disposed thereunder, an electrolyte of copper sulfate-sulfuric acid having the following composition is flowed between the titanium drum and the DSA, and an electric current is flowed between the titanium drum and the DSA so as to flow a 12 μm thick electrode. Copper foil was manufactured.

Electrolyte composition and electrolytic conditions;

Cu = 50 ~ 150g / L

H ₂ SO ₄ = 20 ~ 200g / L

Chloride Ion = 1 ~ 60ppm

Sodium 3-mercapto-1-propane sulfonate = 0.5 to 10 ppm

Polyethylene glycol (average molecular weight 1,000) = 1-30 ppm

Temperature = 30 ~ 70 ℃

Current density: 30-100 A / dm ²

The electrolytic precipitation surface roughness of this copper foil was Rz = 1.3 µm, Ra = 0.3 µm, and the drum surface roughness was Rz = 1.8 µm and Ra = 0.4 µm.

The electron microscope photograph of this electrolytic copper foil was taken, and the drum surface was shown to FIG. 7 (Y1).

Next, after wash | cleaning this copper foil in water, it carried out similarly to Example 1, cathodic electrolysis was performed both sides in the chromium trioxide solution, washed with water, and it dried and it was set as the battery electrolytic copper foil.

The active material similar to Example 1 was apply | coated to this electrolytic copper foil, and preparation and evaluation of the test cell were performed by the same method. The result was written together in Table 1.

As shown in Table 1 and FIGS. 3 to 6, in the embodiment of the present invention, both surfaces of the copper foil have the same surface shape, the electrolytic copper foil is used as a current collector, a cathode electrode is produced, and HEV, EV, PHEV It was an excellent thing which satisfied the battery performance as a lithium ion secondary battery for automobiles.

On the other hand, in Comparative Examples 1 and 2, since the drum surface is in contact with the active material as it is, charging and discharging efficiency is not preferable, and the results are unsatisfactory as a lithium ion secondary battery for automobiles such as HEV, EV, and PHEV.

Furthermore, the present inventors analyzed this phenomenon in detail, and discovered that the difference of the surface shape of a "drum surface" and an "electrolytic precipitation surface" is a big factor.

That is, it turned out that the stripe-shaped unevenness | corrugation of a "drum surface" is easy to cause deterioration by the point of charge / discharge efficiency. Although it is not clear about this cause, it is estimated that the contact area of a negative electrode active material and an electrolytic copper foil is because a contact area is larger in an "electrolytic precipitation surface" than a "drum surface."

This copper foil is useful as copper foil for secondary batteries, especially for lithium ion secondary battery negative electrode collectors.

11, 12: titanium drum 14: DSA
16: first electrolytic cell 17: second electrolytic cell

Claims (6)

In the lithium ion secondary battery provided with the positive electrode, the negative electrode in which the electrode structure active material layer is formed on the surface of an electrical power collector, and a nonaqueous electrolyte, the said electrical power collector which comprises a negative electrode consists of an electrolytic copper foil, Both sides are formed by electrolytic precipitation, The said electrolytic precipitation surface is the crystal | crystallization structure of grain shape crystal | crystallization.
An electrical power collector which comprises the positive electrode, the negative electrode by which the electrode structure active material layer is formed on the surface of an electrical power collector, and the said negative electrode of the lithium ion secondary battery provided with a nonaqueous electrolyte solution, The said electrical power collector consists of an electrolytic copper foil, Both surfaces of an electrolytic copper foil are formed by electrolytic precipitation, The said electrolytic precipitation surface is the collector for lithium ion secondary batteries whose crystal structure of a grain shape crystal | crystallization.
It is an electrolytic copper foil which comprises the said negative electrode electrical power collector of a lithium ion secondary battery provided with a positive electrode, a negative electrode, and a nonaqueous electrolyte solution, Both surfaces of the said electrolytic copper foil are formed by electrolytic precipitation, and the said electrolytic precipitation surface is lithium which is crystal structure of a grain shape crystal | crystallization. Electrolytic copper foil for negative electrode collector of ion secondary batteries.
In the lithium ion secondary battery provided with the negative electrode by which an electrode structure active material layer is formed on the surface of a positive electrode and an electrical power collector, and a nonaqueous electrolyte, the said electrical power collector which comprises a negative electrode is an electrolytic copper foil which electrolytically precipitates copper, and forms it, The 1st surface of the said electrolytic copper foil is a surface formed with the coin crystal of the crystal structure of grain shape on the drum surface, and the 2nd surface on the opposite side to the said 1st surface is behind the 1st surface after 1st surface film-forming. The lithium ion secondary battery which is a surface formed from the coin shape of the crystal structure of grain shape crystal | crystallization.
A negative electrode current collector constituting the secondary battery of a lithium ion secondary battery having a positive electrode, a negative electrode having an electrode constituent active material layer formed on the surface of the current collector, and a nonaqueous electrolyte, and the negative electrode current collector is electrolytic copper It is an electrolytic copper foil which precipitates and forms, The 1st surface of the said electrolytic copper foil is a surface formed with the coin shape of the crystal structure of grain shape on the drum surface, The 2nd surface on the opposite side to the said 1st surface is a 1st surface film forming Later, the negative electrode collector for lithium ion secondary batteries which is a surface formed in the backside of a 1st surface by the coin shape of the crystal structure of grain shape crystal | crystallization.
It is an electrolytic copper foil for the negative electrode collector which comprises the said secondary battery of the lithium ion secondary battery provided with a positive electrode, a negative electrode, and a nonaqueous electrolyte solution, The said electrolytic copper foil is an electrolytic copper foil formed by electrolytically depositing copper, The first surface is a surface formed of coin crystals of grain-crystalline crystals on the drum surface, and the second surface opposite to the first surface is a grain-shaped crystal structure on the rear side of the first surface after the first surface film formation. The electrolytic copper foil for lithium ion secondary battery negative electrode collectors which is the surface formed from the coin-coin of.

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