JP3649373B2 - Method for producing negative electrode current collector for secondary battery - Google Patents
Method for producing negative electrode current collector for secondary battery Download PDFInfo
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- JP3649373B2 JP3649373B2 JP29877298A JP29877298A JP3649373B2 JP 3649373 B2 JP3649373 B2 JP 3649373B2 JP 29877298 A JP29877298 A JP 29877298A JP 29877298 A JP29877298 A JP 29877298A JP 3649373 B2 JP3649373 B2 JP 3649373B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Description
【０００１】
【発明の属する技術分野】
本発明は、リチウムイオン二次電池又はポリマー二次電池用負極集電体の製造方法に関するものである。
【０００２】
【従来の技術】
リチウムイオン二次電池又はポリマー二次電池は、基本的には、正極，負極，正極と負極とを絶縁するセパレーター，及び正極と負極との間でリチウムイオンの移動を可能にするための電解液又はゲル状ポリマー電解質で構成されている。リチウムイオン二次電池又はポリマー二次電池の負極は、金属箔からなる集電体の表面に、各種の活物質が塗布されてなる。この金属箔としては、導電率及びイオン化傾向の観点より、純銅系材料、例えばタフピッチ銅等を用いて得られる銅箔（厚み数μｍ〜数十μｍ程度）が、一般的に採用されている。また、活物質としては、カーボン又はグラファイトと、ポリビニリデンフルオライド（ＰＶＤＦ）等のバインダーとを混合したペースト状物が用いられている。
【０００３】
負極集電体として、上記したような銅箔が用いられるのは、以下の理由による。
（ｉ）電池内で負極集電体は卑な電位を維持しているので、負極集電体として銅箔を用いれば、銅の溶解が生じない。
（ii）銅箔は抗張力が比較的高く、活物質塗布時又は電池製造時、破断する恐れが少ない。
（iii ）二次電池を充電する際、銅箔中の銅は、電解液中のリチウムと電気化学的な合金化が生じにくい。
【０００４】
近年、二次電池の小型化が進むにしたがい、負極集電体である銅箔の薄肉化が求められている。銅箔を薄肉にすると、当然に、銅箔の抗張力が低下する。従って、銅箔の抗張力をより高くすることが求められている。また、二次電池製造工程の合理化乃至は高速化に伴い、活物質の塗布時や負極の巻回時に、負極集電体である銅箔に高張力が付加されることが多くなり、この観点からも、より高い抗張力が求められている。
【０００５】
銅箔により高い抗張力を与えるためには、一般的に、銅に他の元素を添加して、合金化を図ることが行われている。しかし、他の元素を添加すると、銅の利点である上記（iii ）が阻害され、好ましくないと言われていた。即ち、銅以外の他の元素は、リチウムと合金化しやすく、これによって、負極集電体が脆くなると考えられていたのである。これを具体的に述べると、以下のとおりである。リチウムイオン二次電池又はポリマー二次電池は、充電時にはリチウムが負極活物質であるカーボンにドープし、放電時にはリチウムがカーボンから脱ドープするという機構によって、二次電池の機能が与えられている。電気化学的には、負極集電体である銅箔もカーボンと同じ電極電位にさらされるため、負極集電体にリチウムと合金化しやすい元素が存在していると、充電時にはリチウムが負極集電体にドープし、放電時には負極集電体からリチウムが脱ドープするということになる。従って、充放電を何回も繰り返すと、負極集電体は徐々に脆化し、更には負極集電体にひび割れや破損が生じ、集電体としての機能は果たさなくなってしまうのである。以上のような理由で、負極集電体である銅箔に、他の元素を添加することは、なるべく回避しなければならないと考えられていたのである。なお、上記した（ｉ）の観点からは、多くの金属元素は、リチウムイオン二次電池又はポリマー二次電池中で溶解しにくいものであり、添加元素として使用するのに問題はない。
【０００６】
【発明が解決しようとする課題】
以上のような技術的背景の下で、本件発明者等は、銅に特定の他の元素を少量添加して、なるべく上記（iii ）で述べた銅の利点を損なわずに、銅箔の抗張力を高めることを提案した（特願平１０−１４２５７５号）。この発明は、銅９５重量％以上、鉄，ニッケル，クロム，リン，錫及び亜鉛よりなる群から選ばれた一種又は二種以上の元素０．０１〜５重量％なる元素組成を持つ銅合金箔よりなる負極集電体に係るものである。
【０００７】
その後、本件発明者等が研究を進めた結果、予期せぬことに、亜鉛の添加量を更に多くしても、上記（iii ）で述べた銅の利点が損なわれないことが分かった。即ち、亜鉛は、それ単独ではリチウムと合金化しやすい元素であり、例えば、亜鉛箔を負極集電体として使用すると、充電時にリチウムがドープし、放電時にはリチウムが脱ドープし、直ちに亜鉛箔が脆化し、負極集電体としては使用し得ないものである。しかし、特定の製造方法で得られた銅と亜鉛との合金は、亜鉛の含有量が比較的多くても、リチウムと合金化しにくいことを見出したのである。本発明は、このような知見に基づいてなされたものである。
【０００８】
【課題を解決するための手段】
即ち、本発明は、亜鉛５重量％を超え２５重量％以下、その他不可避の不純物元素０．０１重量％以下、残りが銅、よりなる元素組成を持つ鋳塊に、熱間圧延，冷間圧延，中間焼鈍及び仕上圧延を施して圧延合金箔を得ることを特徴とする、該圧延合金箔よりなるリチウムイオン二次電池用負極集電体又はポリマー二次電池用負極集電体の製造方法に関するものである。
【０００９】
まず、本発明において、亜鉛（Ｚｎ）が５重量％を超えて２５重量％以下の割合で含有され、その他不可避の不純物元素０．０１重量％以下、残りが銅、よりなる元素組成を持つ鋳塊を準備する。
【００１０】
鋳塊には、亜鉛と銅（Ｃｕ）とを含んでいるだけでも良いが、その他不可避の不純物元素０．０１重量％以下の割合で混入していても差し支えない。
【００１１】
不可避の不純物元素の量が０．０１重量％を超えると、負極集電体にリチウムのドープ及び脱ドープが起こる可能性が生じ、負極集電体が脆化しやすくなる恐れがある。
【００１２】
鋳塊中の銅の含有量は、亜鉛の含有量によって決定される。即ち、１００重量％から亜鉛の含有量を差し引いた残余の量である。一般的には、７５〜９５重量％程度である。
【００１３】
本発明に係るリチウムイオン二次電池用負極集電体又はポリマー二次電池用負極集電体の製造方法は、以下の方法によって圧延合金箔を得て、これを負極集電体とするものである。即ち、銅と亜鉛を混合して得られた鋳塊に、熱間圧延，冷間圧延，中間焼鈍及び仕上圧延を施して得られた圧延合金箔を、負極集電体とするものである。負極集電体は、仕上圧延を施して加工硬化させた圧延合金箔であっても良いし、仕上圧延のあと最終焼鈍を施して軟化させた圧延合金箔であっても良い。
【００１４】
【００１５】
リチウムイオン二次電池用負極集電体又はポリマー二次電池用負極集電体の厚み、即ち、圧延合金箔の厚みは、５〜１００μｍであるのが好ましく、特に７〜２０μｍであるのがより好ましい。集電体の厚みが５μｍ以下になると、単位平方ミリメートル当たりの引張強さが高くても、全体としての引張強さが低くなる傾向が生じる。また、集電体の厚みが１００μｍを超えると、負極等の極板が厚くなり、二次電池を小型化しにくくなったり、電池容量が低下する傾向が生じる。
【００１６】
本発明に係る方法で得られた負極集電体は、リチウムイオン二次電池又はポリマー二次電池に用いられる。即ち、本発明に係る方法で得られた負極集電体に、種々の活物質を塗布して、リチウムイオン電池又はポリマー電池の負極として用いられるのである。本発明に係る方法で得られた負極集電体は、カーボンやグラファイトよりなる炭素系材料の活物質を、集電体表面に塗布し、これをリチウムイオン二次電池又はポリマー二次電池の負極として用いるのである。
【００１７】
【実施例】
以下、実施例によって本発明を説明するが、本発明は実施例に限定されるものではない。本発明は、特定の製造方法により得られた銅亜鉛合金は、亜鉛の含有量が比較的多くても、リチウムと合金化しにくいという知見に基づいてなされたものと、認識されるべきである。
【００１８】
実施例１及び２、参考例３〜６及び比較例１〜３
電気銅（電解銅）を溶解した上で、表１に記載した添加元素（Ｚｎ，Ｆｅ，Ｎｉ又はＴｉ）を所定量添加して鋳造を行った。そして、鋳造により得られた鋳塊に、熱間圧延を施した後、冷間圧延と中間焼鈍を繰り返し施して、厚み１０μｍの圧延合金箔よりなるリチウムイオン二次電池用負極集電体を得た。なお、繰り返し施した冷間圧延のうち、最後の冷間圧延が仕上圧延ということになる。
【００１９】
【表１】
【００２０】
得られたリチウムイオン二次電池用負極集電体の引張強さ、及び電池劣化までの劣化サイクル数を測定し、その結果を表１に示した。これらの測定方法は、以下のとおりである。
（１）〔引張強さ（Ｎ／ｍｍ2）〕
幅１０ｍｍ、長さ１２０ｍｍの試料片を採取し、負極集電体（圧延銅箔）の圧延方向が試料の長さ方向と一致するようにして、ＪＩＳ Ｚ ２２４１に記載の方法に準拠して測定した。
【００２１】
（２）〔電池劣化までのサイクル数〕
はじめに、以下の方法で測定用小型リチウムイオン電池を作成した。まず、黒鉛系カーボンとフッ素系バインダーの混合物を上記負極集電体表面に塗布して、負極（６０ｍｍ×６００ｍｍ）を得た。一方、コバルト酸リチウムの粉末、フッ素系バインダー及び導電材である黒鉛の混合物を、厚み２０μｍのアルミニウム箔製集電体に塗布して、正極（６０ｍｍ×６００ｍｍ）を得た。そして、負極と正極との間にポリプロピレン製セパレーターを挟み、負極／セパレーター／正極からなる積層体を、絶縁シートを挟みながら渦巻き状に巻回して、直径１８ｍｍで長さ６５ｍｍの円筒型容器に入れた。電解質としてＬｉＢＦ4を用い、溶媒としてエチレンカーボネートとジメチルカーボネートの混合液を用いた電解液を、前記円筒型容器に収納した。そして、正・負極端子を取り出した後、円筒型容器を密閉してリチウムイオン二次電池を作成した。この電池容量は、１３００ｍＡｈであった。
【００２２】
このリチウムイオン二次電池に、電流１．３Ａ（１Ｃ）で１時間の条件で定電流充電後、電池電圧４．２Ｖの定電圧充電を１．５時間行った。放電は、０．２６Ａ（０．２Ｃ）で行い、端子電圧が２．５Ｖまで低下した時点で放電を停止した。このような充放電サイクルを繰り返し施し、電池容量が当初の７０％未満になるまでのサイクル数を、電池劣化までのサイクル数とした。８００サイクルを超える場合には、電池性能として十分良好であると判断して、充放電を停止した。
【００２３】
表１の結果から明らかなように、実施例１及び２に係る負極集電体は、いずれも高い引張強さを持ち、電池劣化までのサイクル数が８００以上であり、十分良好な電池性能を持っている。これに対して、銅１００％の銅箔よりなる負極集電体は、電池性能は十分良好であるが、引張強さが不十分であることが分かる（比較例１）。即ち、銅１００％の銅箔よりなる負極集電体は、４５０（Ｎ／ｍｍ2）の引張強さであるのに対し、銅に所定量の亜鉛を添加含有させてなる圧延合金箔よりなる負極集電体は、６１０〜６８０（Ｎ／ｍｍ2）に引張強さが向上するのである。また、亜鉛の含有量が多すぎる銅亜鉛合金箔よりなる負極集電体は、引張強さは十分であるが、電池劣化までのサイクル数が少なく、電池性能が劣る（比較例２）。更に、亜鉛１００％の亜鉛箔よりなる負極集電体は、引張強さも低いし、電池劣化までのサイクル数も少なく、リチウムイオン二次電池の集電体としては、全く使用できないものである（比較例３）。以上の実施例と比較例とを総合すると、亜鉛１００％では使用不可能であるが、所定の割合の亜鉛を銅と混合すると共に特定の製造方法で負極集電体を得ることにより、電池性能を劣化させるという亜鉛の欠点を消滅させうることが分かる。そして、銅と亜鉛との合金化により、引張強さを向上させうるのである。
【００２４】
【作用及び発明の効果】
以上述べたように、本発明に係る方法で得られたリチウムイオン二次電池用負極集電体又はポリマー二次電池用負極集電体は、銅と比較的多量の亜鉛を含有する圧延合金箔よりなるものである。従って、銅箔よりなる集電体に比べて、銅亜鉛の合金箔よりなるものであるため、引張強さが高い。依って、負極生産時や二次電池生産時において、高引張力を負荷しても切断や破損が生じにくいので、生産の高速度化等の合理化を図ることができるという効果を奏する。また、一般的に、原料として銅よりも亜鉛の方が安価であるので、負極集電体に比較的多量の亜鉛を含有させておくことによって、集電体を廉価にすることができるという効果も奏する。
【００２５】
更に、本発明に係る方法で得られたリチウムイオン二次電池用負極集電体又はポリマー二次電池用負極集電体は、従来、リチウムと合金化し、リチウムイオン二次電池又はポリマー二次電池の性能を劣化させやすいと考えられていた亜鉛を比較的多量に含有するものでありながら、このような常識を覆し、電池性能を劣化させにくいという予期せぬ効果を奏するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a negative electrode current collector for a lithium ion secondary battery or a polymer secondary battery .
[0002]
[Prior art]
A lithium ion secondary battery or a polymer secondary battery basically includes a positive electrode, a negative electrode, a separator that insulates the positive electrode from the negative electrode, and an electrolyte solution that enables lithium ions to move between the positive electrode and the negative electrode. Alternatively, it is composed of a gel polymer electrolyte . A negative electrode of a lithium ion secondary battery or a polymer secondary battery is formed by applying various active materials to the surface of a current collector made of a metal foil. As this metal foil, from the viewpoint of conductivity and ionization tendency, a copper foil (thickness of about several μm to several tens of μm) obtained by using a pure copper-based material such as tough pitch copper is generally employed. As the active material, a paste-like material in which carbon or graphite and a binder such as polyvinylidene fluoride (PVDF) are mixed is used.
[0003]
The copper foil as described above is used as the negative electrode current collector for the following reason.
(I) Since the negative electrode current collector maintains a base potential in the battery, if a copper foil is used as the negative electrode current collector, copper does not dissolve.
(Ii) Copper foil has a relatively high tensile strength and is less likely to break during active material application or during battery production.
(Iii) When charging the secondary battery, the copper in the copper foil is less likely to be electrochemically alloyed with the lithium in the electrolyte.
[0004]
In recent years, with the progress of miniaturization of secondary batteries, there has been a demand for thinning of a copper foil as a negative electrode current collector. When the copper foil is made thin, naturally, the tensile strength of the copper foil is lowered. Accordingly, there is a demand for higher tensile strength of the copper foil. Also, with the rationalization or speeding up of the secondary battery manufacturing process, high tension is often applied to the copper foil as the negative electrode current collector when applying the active material or winding the negative electrode. Therefore, higher tensile strength is required.
[0005]
In order to give a higher tensile strength to the copper foil, generally, other elements are added to copper to achieve alloying. However, it has been said that the addition of other elements inhibits the above (iii), which is an advantage of copper, and is not preferable. That is, elements other than copper were easily alloyed with lithium, which was thought to make the negative electrode current collector brittle. Specifically, this is as follows. A lithium ion secondary battery or a polymer secondary battery is given the function of a secondary battery by a mechanism in which lithium is doped into carbon which is a negative electrode active material during charging and lithium is dedoped from carbon during discharging. Electrochemically, the copper foil, which is the negative electrode current collector, is also exposed to the same electrode potential as that of carbon. Therefore, if an element that is easily alloyed with lithium is present in the negative electrode current collector, the lithium is negatively collected during charging. The body is doped, and at the time of discharge, lithium is dedoped from the negative electrode current collector. Therefore, when the charge and discharge are repeated many times, the negative electrode current collector gradually becomes brittle, and further, the negative electrode current collector is cracked or damaged, and the function as the current collector is not fulfilled. For the reasons described above, it was thought that the addition of other elements to the copper foil as the negative electrode current collector should be avoided as much as possible. From the viewpoint of (i) described above, many metal elements are difficult to dissolve in lithium ion secondary batteries or polymer secondary batteries, and there is no problem in using them as additive elements.
[0006]
[Problems to be solved by the invention]
Under the technical background as described above, the present inventors added a small amount of a specific other element to copper, and as much as possible without damaging the advantages of copper described in (iii) above. (Japanese Patent Application No. 10-142575). The present invention relates to a copper alloy foil having an elemental composition of 0.01 to 5% by weight of one or more elements selected from the group consisting of 95% by weight or more of copper, iron, nickel, chromium, phosphorus, tin and zinc The present invention relates to a negative electrode current collector.
[0007]
Thereafter, as a result of the researches conducted by the inventors of the present invention, it has been unexpectedly found that the advantages of copper described in (iii) above are not impaired even if the amount of zinc added is further increased. That is, zinc is an element that is easily alloyed with lithium by itself. For example, when zinc foil is used as a negative electrode current collector, lithium is doped during charging, lithium is dedoped during discharging, and the zinc foil immediately becomes brittle. And cannot be used as a negative electrode current collector. However, it has been found that an alloy of copper and zinc obtained by a specific manufacturing method is hardly alloyed with lithium even if the content of zinc is relatively large. The present invention has been made based on such knowledge.
[0008]
[Means for Solving the Problems]
That is, the present invention provides hot rolling and cold rolling to an ingot having an elemental composition of more than 5% by weight of zinc and 25 % by weight or less, other inevitable impurity elements of 0.01% by weight or less, and the remainder being copper. , Intermediate annealing and finish rolling to obtain a rolled alloy foil, and a method for producing a negative electrode current collector for a lithium ion secondary battery or a negative electrode current collector for a polymer secondary battery comprising the rolled alloy foil Is.
[0009]
First, in the present invention, zinc (Zn) is contained in a proportion of more than 5% by weight and 25 % by weight or less , other unavoidable impurity elements of 0.01% by weight or less, and the balance of which is copper, the rest of which is an elemental composition. Prepare a lump.
[0010]
The ingot may contain only zinc and copper (Cu), but may contain other inevitable impurity elements of 0.01% by weight or less.
[0011]
If the amount of unavoidable impurity elements exceeds 0.01% by weight, there is a possibility that lithium doping and dedoping may occur in the negative electrode current collector, and the negative electrode current collector may become brittle.
[0012]
The copper content in the ingot is determined by the zinc content. That is, the remaining amount obtained by subtracting the zinc content from 100% by weight. Generally, it is about 75 to 95% by weight.
[0013]
The method for producing a negative electrode current collector for a lithium ion secondary battery or a negative electrode current collector for a polymer secondary battery according to the present invention is obtained by obtaining a rolled alloy foil by the following method and using this as a negative electrode current collector. is there. That is, a rolled alloy foil obtained by subjecting an ingot obtained by mixing copper and zinc to hot rolling, cold rolling, intermediate annealing, and finish rolling is used as a negative electrode current collector. The negative electrode current collector may be a rolled alloy foil that has been work-hardened by finish rolling, or may be a rolled alloy foil that has been softened by final annealing after finish rolling.
[0014]
[0015]
The thickness of the negative electrode current collector for the lithium ion secondary battery or the negative electrode current collector for the polymer secondary battery, that is , the thickness of the rolled alloy foil is preferably 5 to 100 μm, more preferably 7 to 20 μm. preferable. When the thickness of the current collector is 5 μm or less, even if the tensile strength per unit square millimeter is high, the overall tensile strength tends to be low. On the other hand, when the thickness of the current collector exceeds 100 μm, the electrode plate such as the negative electrode becomes thick, and it tends to be difficult to reduce the size of the secondary battery or to decrease the battery capacity.
[0016]
The negative electrode current collector obtained by the method according to the present invention is used for a lithium ion secondary battery or a polymer secondary battery. That is, various active materials are applied to the negative electrode current collector obtained by the method according to the present invention and used as a negative electrode of a lithium ion battery or a polymer battery. A negative electrode current collector obtained by the method according to the present invention is obtained by applying a carbon-based material active material made of carbon or graphite to the surface of a current collector, and applying this to a negative electrode of a lithium ion secondary battery or a polymer secondary battery. It is used as
[0017]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to an Example. It should be recognized that the present invention is based on the knowledge that a copper-zinc alloy obtained by a specific manufacturing method is hardly alloyed with lithium even if the content of zinc is relatively high.
[0018]
Examples 1 and 2, Reference Examples 3 to 6 and Comparative Examples 1 to 3
After dissolving electrolytic copper (electrolytic copper), a predetermined amount of the additive element (Zn, Fe, Ni or Ti) described in Table 1 was added to perform casting. And after performing hot rolling to the ingot obtained by casting , cold rolling and intermediate annealing are repeatedly performed to obtain a negative electrode current collector for a lithium ion secondary battery made of a rolled alloy foil having a thickness of 10 μm. It was. Of the cold rolling performed repeatedly, the last cold rolling is finish rolling.
[0019]
[Table 1]
[0020]
The tensile strength of the obtained negative electrode current collector for a lithium ion secondary battery and the number of deterioration cycles until battery deterioration were measured, and the results are shown in Table 1. These measurement methods are as follows.
(1) [Tensile strength (N / mm 2 )]
A sample piece having a width of 10 mm and a length of 120 mm was taken and measured according to the method described in JIS Z 2241 so that the rolling direction of the negative electrode current collector (rolled copper foil) coincided with the length direction of the sample. did.
[0021]
(2) [Number of cycles until battery deterioration]
First, a small lithium ion battery for measurement was prepared by the following method. First, a mixture of graphite-based carbon and a fluorine-based binder was applied to the surface of the negative electrode current collector to obtain a negative electrode (60 mm × 600 mm). On the other hand, a mixture of lithium cobaltate powder, a fluorine-based binder, and graphite as a conductive material was applied to an aluminum foil current collector with a thickness of 20 μm to obtain a positive electrode (60 mm × 600 mm). Then, a polypropylene separator is sandwiched between the negative electrode and the positive electrode, and the laminate composed of the negative electrode / separator / positive electrode is spirally wound with the insulating sheet sandwiched therebetween, and placed in a cylindrical container having a diameter of 18 mm and a length of 65 mm. It was. An electrolytic solution using LiBF 4 as an electrolyte and a mixed solution of ethylene carbonate and dimethyl carbonate as a solvent was accommodated in the cylindrical container. And after taking out the positive / negative electrode terminal, the cylindrical container was sealed and the lithium ion secondary battery was created. The battery capacity was 1300 mAh.
[0022]
This lithium ion secondary battery was subjected to constant current charging at a current of 1.3 A (1 C) for 1 hour, and then subjected to constant voltage charging at a battery voltage of 4.2 V for 1.5 hours. The discharge was performed at 0.26 A (0.2 C), and the discharge was stopped when the terminal voltage dropped to 2.5 V. Such a charge / discharge cycle was repeatedly performed, and the number of cycles until the battery capacity became less than 70% of the initial value was defined as the number of cycles until battery deterioration. When exceeding 800 cycles, it was judged that the battery performance was sufficiently good, and charging / discharging was stopped.
[0023]
As is clear from the results in Table 1, the negative electrode current collectors according to Examples 1 and 2 both have high tensile strength, and the number of cycles until battery deterioration is 800 or more, so that the battery performance is sufficiently good. have. On the other hand, it can be seen that the negative electrode current collector made of 100% copper foil has sufficiently good battery performance but insufficient tensile strength (Comparative Example 1). That is, the negative electrode current collector made of 100% copper foil has a tensile strength of 450 (N / mm 2 ), whereas it consists of a rolled alloy foil made by adding a predetermined amount of zinc to copper. The negative electrode current collector is improved in tensile strength to 610 to 680 (N / mm 2 ). Moreover, although the negative electrode collector which consists of copper zinc alloy foil with too much zinc content has sufficient tensile strength, there are few cycles to battery deterioration, and battery performance is inferior (comparative example 2). Furthermore, a negative electrode current collector made of 100% zinc foil has a low tensile strength and a small number of cycles until battery deterioration, and cannot be used at all as a current collector for a lithium ion secondary battery ( Comparative Example 3). By combining the above examples and comparative examples, it is impossible to use with 100% zinc, but by mixing a predetermined proportion of zinc with copper and obtaining a negative electrode current collector by a specific manufacturing method , battery performance It can be seen that the defect of zinc, which deteriorates, can be eliminated. And the tensile strength can be improved by alloying copper and zinc.
[0024]
[Operation and effect of the invention]
As described above, the negative electrode current collector for a lithium ion secondary battery or the negative electrode current collector for a polymer secondary battery obtained by the method according to the present invention is a rolled alloy foil containing copper and a relatively large amount of zinc. It is made up of. Accordingly, the tensile strength is higher because the current collector is made of copper-zinc alloy foil than the current collector made of copper foil. Therefore, when producing a negative electrode or a secondary battery, even if a high tensile force is applied, cutting and breakage are unlikely to occur, so that the production speed can be rationalized. In general, since zinc is cheaper than copper as a raw material, the current collector can be made inexpensive by containing a relatively large amount of zinc in the negative electrode current collector. Also play.
[0025]
Furthermore, the negative electrode current collector for a lithium ion secondary battery or the negative electrode current collector for a polymer secondary battery obtained by the method according to the present invention has been conventionally alloyed with lithium to produce a lithium ion secondary battery or a polymer secondary battery. Although it contains a relatively large amount of zinc, which has been considered to easily deteriorate the performance of the battery, it reverses this common sense and has the unexpected effect of hardly deteriorating the battery performance.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29877298A JP3649373B2 (en) | 1998-10-20 | 1998-10-20 | Method for producing negative electrode current collector for secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29877298A JP3649373B2 (en) | 1998-10-20 | 1998-10-20 | Method for producing negative electrode current collector for secondary battery |
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| Publication Number | Publication Date |
|---|---|
| JP2000133276A JP2000133276A (en) | 2000-05-12 |
| JP3649373B2 true JP3649373B2 (en) | 2005-05-18 |
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| JP29877298A Expired - Lifetime JP3649373B2 (en) | 1998-10-20 | 1998-10-20 | Method for producing negative electrode current collector for secondary battery |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3733067B2 (en) | 1999-10-22 | 2006-01-11 | 三洋電機株式会社 | Lithium battery electrode and lithium secondary battery |
| AU7951100A (en) | 1999-10-22 | 2001-04-30 | Sanyo Electric Co., Ltd. | Electrode for lithium secondary cell and lithium secondary cell |
| JP3733065B2 (en) * | 1999-10-22 | 2006-01-11 | 三洋電機株式会社 | Lithium battery electrode and lithium secondary battery |
| EP1244163A4 (en) | 1999-10-22 | 2007-10-31 | Sanyo Electric Co | Electrode for lithium secondary cell and lithium secondary cell |
| JP3733071B2 (en) | 1999-10-22 | 2006-01-11 | 三洋電機株式会社 | Lithium battery electrode and lithium secondary battery |
| WO2001084654A1 (en) | 2000-04-26 | 2001-11-08 | Sanyo Electric Co., Ltd. | Lithium secondary battery-use electrode and lithium secondary battery |
| KR100416097B1 (en) * | 2001-10-19 | 2004-01-24 | 삼성에스디아이 주식회사 | Anode current collector and lithium battery employing the same |
| KR101154545B1 (en) * | 2009-11-23 | 2012-06-13 | 지에스나노텍 주식회사 | Thin film battery hving improved efficiency of collecting electric current |
| CN110684911A (en) * | 2018-07-04 | 2020-01-14 | 有研工程技术研究院有限公司 | Cathode material of hollow cathode zinc lamp and preparation method thereof |
| CN114400331A (en) * | 2022-03-03 | 2022-04-26 | 电子科技大学 | Preparation method of negative current collector capable of improving lithium metal cycle stability |
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1998
- 1998-10-20 JP JP29877298A patent/JP3649373B2/en not_active Expired - Lifetime
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