JP2019008957A - Method for manufacturing positive electrode film for lithium ion secondary battery - Google Patents

Method for manufacturing positive electrode film for lithium ion secondary battery Download PDF

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JP2019008957A
JP2019008957A JP2017122817A JP2017122817A JP2019008957A JP 2019008957 A JP2019008957 A JP 2019008957A JP 2017122817 A JP2017122817 A JP 2017122817A JP 2017122817 A JP2017122817 A JP 2017122817A JP 2019008957 A JP2019008957 A JP 2019008957A
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JP6907755B2 (en
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若林 正男
Masao Wakabayashi
正男 若林
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Sumitomo Metal Mining Co Ltd
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Abstract

To provide a method for manufacturing a lithium ion secondary battery, by which battery characteristics can be evaluated with high accuracy and stability.SOLUTION: A method for manufacturing a positive electrode film for a lithium ion secondary battery comprises: a mixing step of putting, in a resin closed container, first powder of a positive electrode active material capable of occluding and releasing a lithium ion, and second powder including at least a conductive assistant and a binding agent together with 15-30 pts.mass of ceramic balls to a total of 1 pt.mass of the first powder and the second powder and mixing them by a centrifugal planetary motion type kneader of which the number of revolutions is 100-400 rpm and the rotation rate is 1/3; and a molding step of molding a powder mixture obtained in the mixing step to manufacture a positive electrode film. In the method, the mixing step and molding step are performed under an atmosphere of 1.2 g/mor less in absolute humidity.SELECTED DRAWING: None

Description

本発明は、リチウムイオン二次電池用の正極膜の製造方法に関する。   The present invention relates to a method for producing a positive electrode film for a lithium ion secondary battery.

リチウムイオン二次電池は、エネルギー密度が大きく且つ寿命が長いなどの特徴を有しているため、ビデオカメラ等の家電製品や、ノート型パソコン、携帯電話機等の携帯型電子機器などの電源として用いられており、最近では、電気自動車(EV)やハイブリッド電気自動車(HEV)搭載用の二次電池、バックアップ電源に搭載される大型電池などにも利用されている。   Lithium ion secondary batteries are characterized by high energy density and long life, so they are used as power sources for home appliances such as video cameras, portable electronic devices such as notebook computers and mobile phones. Recently, it is also used for secondary batteries for mounting electric vehicles (EV) and hybrid electric vehicles (HEV), large batteries mounted on a backup power source, and the like.

リチウムイオン二次電池の基本的な構造は、セパレーターを挟んで対向させた正極膜と負極膜との間に電解質を満たした構造を有している。かかる構造のリチウムイオン二次電池を高電位で作動させるためには、電解質が高電位においても分解されないのが望ましい。そこで4.5V程度の酸化還元電位でも分解されない特徴を持つヘキサフルオロリン酸リチウム(LiPF)が、リチウムイオン二次電池の電解質として広く用いられている。 The basic structure of a lithium ion secondary battery has a structure in which an electrolyte is filled between a positive electrode film and a negative electrode film opposed to each other with a separator interposed therebetween. In order to operate a lithium ion secondary battery having such a structure at a high potential, it is desirable that the electrolyte is not decomposed even at a high potential. Accordingly, lithium hexafluorophosphate (LiPF 6 ), which has a feature that is not decomposed even at an oxidation-reduction potential of about 4.5 V, is widely used as an electrolyte for lithium ion secondary batteries.

例えば特許文献1には、リチウムニッケル複合酸化物からなる正極活物質粉末にアセチレンブラック及びPTFEを混合してペレット状に作製した正極と、リチウム金属等からなる負極とからなる二次電池において、非水系電解液の支持塩のリチウム塩にLiPFを使用する技術が開示されている。 For example, Patent Document 1 discloses a secondary battery composed of a positive electrode active material powder made of a lithium nickel composite oxide mixed with acetylene black and PTFE into a pellet and a negative electrode made of lithium metal or the like. A technique using LiPF 6 as a lithium salt as a supporting salt of an aqueous electrolyte is disclosed.

特開2012−119093号公報JP 2012-119093 A

しかし、LiPFは水との反応性が高く、空気中の湿気により加水分解するため取扱いに注意を要する。例えば電解質にLiPFを用いた二次電池を作製する場合は、空気中の湿気を除去した環境下で正極膜や負極膜などの部材を製造して二次電池を組み立てることが必要となる。その理由は、二次電池の製造段階で電池内部に微量の水分が混入するとLiPFが加水分解し、これにより生成したLiなどの成分がセパレーターなどの部材に付着して電池内部で短絡を起こしたり、フッ化水素(HF)が正極活物質を溶解したりするため、電池特性を安定的に評価できないことがあった。 However, LiPF 6 is highly reactive with water, and is hydrolyzed by moisture in the air. For example, in the case of producing a secondary battery using LiPF 6 as an electrolyte, it is necessary to assemble a secondary battery by manufacturing members such as a positive electrode film and a negative electrode film in an environment where moisture in the air is removed. The reason is that LiPF 6 is hydrolyzed when a small amount of water is mixed in the battery during the manufacturing process of the secondary battery, and components such as Li adhere to the separator and other members and cause a short circuit inside the battery. In addition, since hydrogen fluoride (HF) dissolves the positive electrode active material, battery characteristics may not be stably evaluated.

また、リチウムイオン二次電池に用いられる正極膜は、LiCoOやLiNiO等からなる正極活物質とカーボンブラック等からなる導電助剤とを含む合剤層が集電体上に形成されたものが用いられる。これら正極活物質と導電助剤は粒径が互いに異なるので混合されにくく、よって電池特性を精度よく安定的に評価できないことがあった。本発明は上記の問題に鑑みてなされたものであり、リチウムイオン二次電池の電池特性を高い精度で安定的に評価することが可能なリチウムイオン二次電池用正極膜の製造方法を提供することを目的としている。 Further, positive electrode film used for lithium ion secondary batteries, which mixture layer comprising a conductive auxiliary agent consisting of a positive electrode active material and carbon black or the like consisting of LiCoO 2 and LiNiO 2 or the like is formed on the current collector Is used. Since these positive electrode active materials and conductive assistants have different particle sizes, they are difficult to be mixed, and thus battery characteristics may not be evaluated accurately and stably. The present invention has been made in view of the above problems, and provides a method for producing a positive electrode film for a lithium ion secondary battery capable of stably evaluating the battery characteristics of the lithium ion secondary battery with high accuracy. The purpose is that.

上記目的を達成するため、本発明のリチウムイオン二次電池用正極膜の製造方法は、リチウムイオンを吸脱蔵可能な正極活物質からなる第1粉末と、少なくとも導電助剤及び結着剤を含んだ第2粉末とを、該第1粉末及び第2粉末の合計1質量部に対して15〜30質量部のセラミックボールと共に樹脂製の密閉容器に装入し、公転側の回転数100〜400rpm、自転比1/3の遠心遊星運動式混練機を用いて混合する混合工程と、前記混合工程で得られた混合粉末を成型して正極膜を製造する成型工程とからなるリチウムイオン二次電池用正極膜の製造方法であって、前記の混合工程及び成型工程を絶対湿度1.2g/m以下の雰囲気下で行うことを特徴としている。 In order to achieve the above object, a method for producing a positive electrode film for a lithium ion secondary battery according to the present invention comprises a first powder comprising a positive electrode active material capable of absorbing and desorbing lithium ions, and at least a conductive additive and a binder. The contained second powder is charged into a resin-made airtight container together with 15 to 30 parts by mass of ceramic balls with respect to a total of 1 part by mass of the first powder and the second powder, and the revolution speed of 100 to 100 Lithium ion secondary comprising a mixing step of mixing using a centrifugal planetary motion kneader with 400 rpm and a rotation ratio of 1/3, and a forming step of forming a positive electrode film by forming the mixed powder obtained in the mixing step A method for producing a positive electrode film for a battery, wherein the mixing step and the molding step are performed in an atmosphere having an absolute humidity of 1.2 g / m 3 or less.

本発明によれば、リチウムイオン二次電池の電池特性を高い精度で安定的に評価することができる。   According to the present invention, the battery characteristics of a lithium ion secondary battery can be stably evaluated with high accuracy.

本発明の一具体例の2023型コイン電池の部分断面正面図である。It is a partial cross section front view of the 2023 type coin battery of one example of the present invention.

リチウムイオン二次電池は、リチウム遷移金属複合酸化物からなる正極活物質を含む正極膜と、カーボン等からなる負極膜とをセパレーターを介して対向するように配置し、これら正極膜と負極膜との間に電解質を含浸することで作製することができる。本発明は、これらの構成要素のうち正極膜を対象としている。以下、本発明のリチウムイオン二次電池用正極膜の製造方法の実施形態について説明する。   In the lithium ion secondary battery, a positive electrode film containing a positive electrode active material made of a lithium transition metal composite oxide and a negative electrode film made of carbon or the like are arranged so as to face each other with a separator interposed therebetween. It can be produced by impregnating the electrolyte between the two. The present invention is directed to the positive electrode film among these components. Hereinafter, an embodiment of a method for producing a positive electrode film for a lithium ion secondary battery of the present invention will be described.

この本発明の実施形態のリチウムイオン二次電池正極膜の製造方法は、先ずリチウム、ニッケル、コバルト、マンガン、アルミニウムなどの遷移金属の複合酸化物からなる正極活物質の第1粉末と、アセチレンブラックなどのカーボンを主成分とする導電助剤とポリテトラフルオロエチレン等の有機系バインダー(結着材)とで構成される第2粉末とを混合することが行われる(混合工程)。この混合工程で得た混合粉末を、次に金型に装入してプレス成型する(成型工程)。これにより、所定の形状を有する正極膜が得られる。   The method for producing a positive electrode film of a lithium ion secondary battery according to an embodiment of the present invention includes a first powder of a positive electrode active material composed of a composite oxide of transition metals such as lithium, nickel, cobalt, manganese, and aluminum, and acetylene black. The second powder composed of a conductive additive mainly composed of carbon and the like and an organic binder (binder) such as polytetrafluoroethylene is mixed (mixing step). Next, the mixed powder obtained in this mixing step is charged into a mold and press-molded (molding step). Thereby, a positive electrode film having a predetermined shape is obtained.

電池特性の評価では正極活物質の単位質量当たりの充放電容量で評価されるため、正極膜の質量が正確に測定できないと充放電容量の測定精度が低下する。そこで、正極膜の秤量は上記の成型後に行うのが好ましい。これは、秤量してから成型すると、金型への装入時やプレス時に正極活物質や導電助剤が一部失われるため、測定精度が低下するおそれがあるからである。更に、本発明の実施形態の正極膜の製造方法では、以下の要領で混合及び成型が行われる。   In the evaluation of battery characteristics, the charge / discharge capacity per unit mass of the positive electrode active material is evaluated. Therefore, if the mass of the positive electrode film cannot be measured accurately, the measurement accuracy of the charge / discharge capacity decreases. Therefore, it is preferable to weigh the positive electrode film after the above molding. This is because, when molding after weighing, a part of the positive electrode active material and the conductive auxiliary agent are lost at the time of charging into the mold or at the time of pressing, so that the measurement accuracy may be lowered. Furthermore, in the manufacturing method of the positive electrode film of the embodiment of the present invention, mixing and molding are performed in the following manner.

先ず混合工程では、遠心遊星運動式混練機を使用する。その理由は、粉末の混合機には、乾式ボールミル、乾式ビーズミル、ブレード遊星運動型の混合器、擂潰機、ホモジナイザーなどがあるが、これらに比べて容器が自転及び公転する遊星運動式混練機は、ボールと共に粉末を混合することで極めて均一な混合が短時間で可能であるので、二次電池の電池特性を高い精度で安定的に行うのに適しているからである。   First, in the mixing step, a centrifugal planetary kneader is used. The reason for this is that powder mixers include dry ball mills, dry bead mills, blade planetary motion type mixers, crushers, homogenizers, etc. This is because extremely uniform mixing is possible in a short time by mixing the powder together with the balls, which is suitable for stably performing the battery characteristics of the secondary battery with high accuracy.

上記の容器には、金属不純物の混入を避けるため、樹脂製の容器を使用する。その理由は、被混合粉末及びボールを入れる容器が金属やセラミックであればコンタミネーションの問題が生じうる上、これら材質は樹脂に比べて重いため高速回転させることが困難であり、よって十分に混合することができないため好ましくないからである。このような樹脂製の容器としては、例えば密閉可能なポッドミルを挙げることができる。被混合粉末と共に上記容器に装入するボールには、金属不純物の混入を抑え且つ十分な混合が得られるようにするため、アルミナやマグネシアなどのセラミックボールを用いる。   In order to avoid mixing metal impurities, a resin container is used for the container. The reason for this is that if the container for mixing powder and balls is made of metal or ceramic, contamination problems may occur, and these materials are heavy compared to resin, making them difficult to rotate at high speeds. This is because it cannot be performed. An example of such a resin container is a pod mill that can be sealed. A ceramic ball such as alumina or magnesia is used for the ball charged into the container together with the powder to be mixed in order to suppress mixing of metal impurities and to obtain sufficient mixing.

このセラミックボールは、上記の第1粉末及び第2粉末の合計1質量部に対して15〜30質量部を上記の容器に装入する。この装入量が30質量部よりも多いと、混合の際に上記第1粉末や第2粉末がセラミックボールによって容器の壁面に強く押圧されて付着することがあった。この場合、容器からの付着物の取出しが困難になって電池測定の精度が低下することがある。また、正極活物質粒子がセラミックボールから過度な応力を受けてその一部が破壊したり結晶内に歪みが生じたりして充放電容量が低下するおそれがある。逆に、この装入量が15質量部より少ないと、導電助剤の凝集を粉砕するための応力が不十分となり、正極活物質に対して導電助剤を十分に分散させ且つ密着性を持たせることができなくなり、充放電容量が低下するおそれがある。   In this ceramic ball, 15 to 30 parts by mass are charged into the container with respect to a total of 1 part by mass of the first powder and the second powder. When the charging amount is more than 30 parts by mass, the first powder and the second powder may be strongly pressed and adhered to the wall surface of the container by the ceramic ball during mixing. In this case, it becomes difficult to remove the deposits from the container, and the accuracy of battery measurement may be reduced. In addition, the positive electrode active material particles may receive excessive stress from the ceramic balls, and some of the positive electrode active material particles may be broken or distortion may occur in the crystal, resulting in a decrease in charge / discharge capacity. On the other hand, when the amount of charging is less than 15 parts by mass, the stress for pulverizing the aggregation of the conductive auxiliary agent becomes insufficient, and the conductive auxiliary agent is sufficiently dispersed in the positive electrode active material and has adhesiveness. The charging / discharging capacity may be reduced.

上記したようにセラミックボールの装入量を限定することで得られる効果を奏するためには遊星運動式混練機の公転の回転数を100rpm以上400rpm以下にし、且つ公転の回転数に対する自転の回転数の比(以下、自転比とも称する)を1/3にする。この公転の回転数が400rpmより大きいと、前述したように正極活物質や導電助剤が容器の壁面に付着してしまい、適正な混合比で正極膜を作製することが困難になって測定精度と充放電容量が低下するおそれがある。逆に、回転数が100rpmよりも小さいと、前述したように凝集しやすい導電助剤の混合が不十分になって、正極活物質に対して導電助剤を十分に分散させ且つ密着性を持たせることができなくなり、充放電容量が低下するおそれがある。   In order to achieve the effect obtained by limiting the amount of ceramic balls charged as described above, the revolution speed of the planetary kneader is set to 100 rpm or more and 400 rpm or less, and the rotation speed relative to the revolution speed Ratio (hereinafter also referred to as rotation ratio) is 1/3. If the revolution speed is greater than 400 rpm, the positive electrode active material and the conductive auxiliary agent adhere to the wall surface of the container as described above, and it becomes difficult to produce a positive electrode film with an appropriate mixing ratio. The charge / discharge capacity may be reduced. On the other hand, when the rotational speed is less than 100 rpm, as described above, the mixing of the conductive auxiliary agent that easily aggregates becomes insufficient, and the conductive auxiliary agent is sufficiently dispersed in the positive electrode active material and has adhesiveness. The charging / discharging capacity may be reduced.

本発明の実施形態の正極膜の製造方法では、上記の混合工程及び成形工程を絶対湿度1.2g/m以下の雰囲気下で行うようにする。この絶対湿度が1.2g/mを超える雰囲気では、正極活物質、導電助剤、及び結着剤のうちの少なくともいずれかが吸湿して凝集が起こりやすくなり、混合工程において相互に良好に分散しなくなるため好ましくない。また、電解質にLiPFが用いられている場合、LiPFは空気中に含まれる水分や電池部材に僅かに混入する水分で分解し、これにより生成したLiなどの成分が電池部材に付着し短絡を生じさせたり、HFなどを発生させて正極活物質中からの金属成分の溶出などを引き起こしたりするため、正確な電池特性の評価ができなくなる。 In the method for producing a positive electrode film according to the embodiment of the present invention, the mixing step and the forming step are performed in an atmosphere having an absolute humidity of 1.2 g / m 3 or less. In an atmosphere where the absolute humidity exceeds 1.2 g / m 3 , at least one of the positive electrode active material, the conductive auxiliary agent, and the binder tends to absorb moisture and easily agglomerate. This is not preferable because it is not dispersed. When LiPF 6 is used as the electrolyte, LiPF 6 is decomposed by moisture contained in the air or moisture slightly mixed in the battery member, and components such as Li generated thereby adhere to the battery member and are short-circuited. Or the generation of HF or the like to cause elution of a metal component from the positive electrode active material, making it impossible to accurately evaluate the battery characteristics.

なお、上記のように空気中の水分を除去した乾燥雰囲気下で取り扱われた正極活物質は帯電しやすく、特に混合時は正極活物質と導電助剤が飛散しやすくなる。リチウムイオン二次電池の充放電容量は、前述したように正極活物質の単位質量当たりの電気容量(mAh/g)として評価されるため、正極活物質と導電助剤が飛散すると各々の重量精度が失われ、充放電容量を正確且つ安定的に評価することが困難となる。このような場合であっても、上記したように混合の際に密閉容器を用いているので特に問題はない。   Note that the positive electrode active material handled in a dry atmosphere from which moisture in the air has been removed as described above is easily charged, and particularly when mixed, the positive electrode active material and the conductive auxiliary agent are likely to be scattered. Since the charge / discharge capacity of the lithium ion secondary battery is evaluated as the electric capacity (mAh / g) per unit mass of the positive electrode active material as described above, each weight accuracy when the positive electrode active material and the conductive additive are scattered. It becomes difficult to accurately and stably evaluate the charge / discharge capacity. Even in such a case, there is no particular problem because a sealed container is used for mixing as described above.

上記の本発明の実施形態の製造方法で作製した正極膜は真空中で120℃で乾燥した後、引き続き絶対湿度1.2g/m以下の雰囲気下で二次電池を組み立てることが好ましい。その理由は、絶対湿度の低い環境下で作成された正極膜は極めて吸水しやすい状態にあるので、空気に晒すと容易に空気中の水分を吸収して電池内部に水分を混入させてしまい、時間の経過に伴ってLiPFを加水分解して短絡や電池容量の低下を発生させるおそれがあるからである。 It is preferable to assemble the secondary battery in an atmosphere having an absolute humidity of 1.2 g / m 3 or less after drying the positive electrode film produced by the manufacturing method of the above-described embodiment of the present invention at 120 ° C. in vacuum. The reason is that the positive electrode film created in an environment with low absolute humidity is in a state that it is very easy to absorb water, so when exposed to air, it easily absorbs moisture in the air and mixes moisture inside the battery, This is because LiPF 6 may be hydrolyzed with time to cause a short circuit or a decrease in battery capacity.

上記の正極膜に対向させる負極膜には、カーボン負極などの一般的なリチウムイオン二次電池に用いられる負極膜を用いることができるが、電池特性の評価を目的とした電池を作製する場合は、金属リチウム又はリチウムを主成分とする金属からなる負極を用いることが多い。このような負極を用いた電池は、作製が容易であり、少量の電池を迅速に作製する必要がある評価用電池として好ましい。   As the negative electrode film facing the positive electrode film, a negative electrode film used for a general lithium ion secondary battery such as a carbon negative electrode can be used. However, when a battery for the purpose of evaluating battery characteristics is manufactured. In many cases, a negative electrode made of metallic lithium or a metal containing lithium as a main component is used. A battery using such a negative electrode is easy to produce, and is preferable as an evaluation battery that needs to produce a small amount of battery quickly.

また、上記の正極膜と負極膜の間に配置するセパレーターは、正極と負極間の絶縁及び電解液の保持などの一般的な機能を有するものであれば特に限定はなく、ポリエチレン(PE)、ポリプロピレン(PP)、あるいはそれら積層品等の多孔膜などのリチウムイオン二次電池で使用されているものを用いることができる。なお、上記した以外の二次電池の作製方法や使用する材料等は通常の非水系電解液電池の作製と同様に行うことができ、また、二次電池の構造も通常のものと同様にすることができる。   In addition, the separator disposed between the positive electrode film and the negative electrode film is not particularly limited as long as it has general functions such as insulation between the positive electrode and the negative electrode and retention of the electrolytic solution, polyethylene (PE), What is used with lithium ion secondary batteries, such as porous films, such as polypropylene (PP) or those laminated products, can be used. In addition, the manufacturing method of secondary batteries other than those described above, the materials used, and the like can be performed in the same manner as in the manufacturing of a normal nonaqueous electrolyte battery, and the structure of the secondary battery is the same as that of a normal battery. be able to.

[実施例1]
正極活物質の材料として、公知技術で得られるLi1.060Ni0.76Co0.14Al0.10で表されるリチウムニッケル複合酸化物粉末の第1粉末を用意した。また、導電助剤としてのアセチレンブラック粉末と、結着剤としてのポリエチレンテトラフルオロエチレン(PTFE)とが質量比2:1で混合された第2粉末を用意した。気温23.5℃、相対湿度5%(絶対湿度1.06g/m)の雰囲気下で、上記第1粉末1.05gと、第2粉末0.45gとをそれぞれ量り取って内径45mmφのポリエチレン製の密閉可能な容器に3mmφのジルコニアボール30gと共に装入し、株式会社日本精機製作所製のノンバブリングニーダー(NBK-1)で公転回転数100rpm、自転比1/3で30秒間混合した。
[Example 1]
As a positive electrode active material, a first powder of lithium nickel composite oxide powder represented by Li 1.060 Ni 0.76 Co 0.14 Al 0.10 O 2 obtained by a known technique was prepared. Moreover, the 2nd powder with which acetylene black powder as a conductive support agent and polyethylenetetrafluoroethylene (PTFE) as a binder were mixed by mass ratio 2: 1 was prepared. In an atmosphere having an air temperature of 23.5 ° C. and a relative humidity of 5% (absolute humidity: 1.06 g / m 3 ), 1.05 g of the first powder and 0.45 g of the second powder were weighed to obtain polyethylene having an inner diameter of 45 mmφ. The product was placed in a sealable container made of 30 mm together with 3 g of zirconia balls having a diameter of 3 mm, and mixed for 30 seconds using a non-bubbling kneader (NBK-1) manufactured by Nippon Seiki Seisakusho at a revolution speed of 100 rpm and a rotation ratio of 1/3.

得られた混合粉末から気温23.5℃、相対湿度5%(絶対湿度1.06g/m)の雰囲気下で75mgを量り取ってプレス成型用の金型に装入し、エヌピーエーシステム株式会社製の5t手動式テーブルプレス(TB−50H−V09)により11mmφのディスク形状の正極膜を成型した。得られた正極膜を真空中100℃で16時間乾燥した。乾燥後の正極膜の質量を秤量したところ、75.0mgであった。この正極膜中に含まれる正極活物質は、上記の混合比率から算出すると52.5mgとなる。同様の方法を繰り返し、合計10個の正極膜を作製した。 75 mg of the resulting mixed powder was weighed in an atmosphere of 23.5 ° C. and 5% relative humidity (1.06 g / m 3 ) relative humidity, and placed in a press mold. A disk-shaped positive electrode film having a diameter of 11 mmφ was formed by a company-made 5t manual table press (TB-50H-V09). The obtained positive electrode film was dried in vacuum at 100 ° C. for 16 hours. When the mass of the positive electrode film after drying was weighed, it was 75.0 mg. The positive electrode active material contained in the positive electrode film is 52.5 mg when calculated from the above mixing ratio. The same method was repeated to produce a total of 10 positive electrode films.

更に下記の部材を用意して、図1に示すような評価用の2032型コイン電池を作製した。具体的には、上記にて作製した円形正極膜1に対向する円形負極膜2として厚み1.0mmの金属リチウムを直径14mmに打ち抜いた金属リチウムディスクを用意し、これらの間に介在させるセパレーター3として、ガラス濾紙(アドバンテック:GF-75)を用意した。電解液は、LiPFを1モル/L含有する、エチレンカーボネート(EC)とジエチルカーボネート(DEC)の等モル量混合液(容積比でEC/DEC=3/7)を用いた。更に、これらを収納する正極缶4及び負極缶5、これら正極缶4及び負極缶5が互いに係合する周縁部をシールするガスケット6、並びに円形負極膜2の上に設けるウェーブワッシャー7を用意した。 Furthermore, the following members were prepared to produce a 2032 type coin battery for evaluation as shown in FIG. Specifically, a separator 3 is prepared by preparing a metallic lithium disk in which a metallic lithium having a thickness of 1.0 mm is punched out to a diameter of 14 mm as the circular negative electrode film 2 facing the circular positive electrode film 1 produced above. A glass filter paper (Advantech: GF-75) was prepared. As the electrolytic solution, an equimolar mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) containing 1 mol / L of LiPF 6 (EC / DEC = 3/7 in volume ratio) was used. Furthermore, a positive electrode can 4 and a negative electrode can 5 that house them, a gasket 6 that seals the peripheral edge where the positive electrode can 4 and the negative electrode can 5 engage with each other, and a wave washer 7 provided on the circular negative electrode film 2 were prepared. .

これら部材を用いて露点−65℃以下に保ったグローブボックス中でコイン電池を組み立てた。同様の方法によって合計10個のコイン電池を作製した。そして、これら10個のコイン電池の各々に対して、0.4mAの定電流で4.3Vまで充電を行った後、0.4mAの定電流で3.0Vまで放電を行って充放電特性を評価した。得られた10個の初期放電容量の平均値と、その分散を求めた。   Using these members, a coin battery was assembled in a glove box maintained at a dew point of −65 ° C. or lower. A total of 10 coin batteries were produced by the same method. Each of these ten coin batteries is charged to 4.3 V with a constant current of 0.4 mA, and then discharged to 3.0 V with a constant current of 0.4 mA to obtain charge / discharge characteristics. evaluated. The average value of the obtained 10 initial discharge capacities and their dispersion were determined.

[実施例2]
秤量時及び作製時の雰囲気の相対湿度を5%に代えて4%(絶対湿度0.85g/m)とした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Example 2]
Ten 2032 type coin batteries were prepared and charged in the same manner as in Example 1 except that the relative humidity of the atmosphere during weighing and production was changed to 4% (absolute humidity 0.85 g / m 3 ) instead of 5%. The discharge characteristics were evaluated.

[実施例3]
ジルコニアボールの装入量を30gに代えて25gにした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Example 3]
Ten 2032 type coin batteries were produced in the same manner as in Example 1 except that the amount of zirconia balls was changed to 25 g instead of 30 g, and the charge / discharge characteristics were evaluated.

[実施例4]
ジルコニアボールの装入量を30gに代えて35gにした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Example 4]
Ten 2032 type coin batteries were produced in the same manner as in Example 1 except that the amount of zirconia balls charged was 35 g instead of 30 g, and the charge / discharge characteristics were evaluated.

[実施例5]
第1粉末及び第2粉末の混合割合を1.05g及び0.45gに代えて0.7g及び0.3gとした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Example 5]
Ten 2032 type coin batteries were prepared and charged in the same manner as in Example 1 except that the mixing ratio of the first powder and the second powder was changed to 0.7 g and 0.3 g instead of 1.05 g and 0.45 g. The discharge characteristics were evaluated.

[実施例6]
第1粉末及び第2粉末の混合割合を1.05g及び0.45gに代えて1.4g及び0.6gとした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Example 6]
Ten 2032 type coin batteries were prepared in the same manner as in Example 1 except that the mixing ratio of the first powder and the second powder was changed to 1.4 g and 0.6 g instead of 1.05 g and 0.45 g. The discharge characteristics were evaluated.

[実施例7]
ノンバブリングニーダーの公転回転数を100rpmに代えて400rpmとした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Example 7]
Ten 2032 type coin batteries were produced in the same manner as in Example 1 except that the revolution speed of the non-bubbling kneader was changed to 400 rpm instead of 100 rpm, and the charge / discharge characteristics were evaluated.

[比較例1]
秤量時及び作製時の雰囲気の相対湿度を5%に代えて6%(絶対湿度1.27g/m)とした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Comparative Example 1]
Ten 2032 type coin batteries were prepared and charged in the same manner as in Example 1 except that the relative humidity of the atmosphere at the time of weighing and preparation was changed to 6% (absolute humidity 1.27 g / m 3 ) instead of 5%. The discharge characteristics were evaluated.

[比較例2]
ジルコニアボールの装入量を30gに代えて20gにした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Comparative Example 2]
Ten 2032 type coin batteries were produced in the same manner as in Example 1 except that the amount of zirconia balls was changed to 20 g instead of 30 g, and charge / discharge characteristics were evaluated.

[比較例3]
ジルコニアボールの装入量を30gに代えて50gにした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Comparative Example 3]
Ten 2032 type coin batteries were produced in the same manner as in Example 1 except that the amount of zirconia balls was changed to 50 g instead of 30 g, and the charge / discharge characteristics were evaluated.

[比較例4]
第1粉末及び第2粉末の混合割合を1.05g及び0.45gに代えて0.63g及び0.27gとした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Comparative Example 4]
Ten 2032 type coin batteries were prepared in the same manner as in Example 1 except that the mixing ratio of the first powder and the second powder was changed to 0.63 g and 0.27 g instead of 1.05 g and 0.45 g. The discharge characteristics were evaluated.

[比較例5]
第1粉末及び第2粉末の混合割合を1.05g及び0.45gに代えて1.47g及び0.63gとした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。
[Comparative Example 5]
Ten 2032 type coin batteries were prepared in the same manner as in Example 1 except that the mixing ratio of the first powder and the second powder was changed to 1.47 g and 0.63 g instead of 1.05 g and 0.45 g. The discharge characteristics were evaluated.

[比較例6]
ノンバブリングニーダーの公転回転数を100rpmに代えて450rpmとした以外は実施例1と同様にして2032型コイン電池を10個作製し、充放電特性を評価した。上記の実施例1〜7及び比較例1〜6の評価結果を下記表1に示す。
[Comparative Example 6]
Ten 2032 type coin batteries were produced in the same manner as in Example 1 except that the revolution speed of the non-bubbling kneader was changed to 450 rpm instead of 100 rpm, and the charge / discharge characteristics were evaluated. The evaluation results of Examples 1 to 7 and Comparative Examples 1 to 6 are shown in Table 1 below.

Figure 2019008957
Figure 2019008957

上記表1から分かるように、実施例1〜7では正極膜の原料の秤量及び作製を絶対湿度1.2g/m以下の雰囲気下で行ったため、平均初期放電容量はいずれも195mAh/g以上となった。これに対して、比較例1では正極膜の原料の秤量及び作製を絶対湿度1.2g/mを超えた雰囲気下で行ったため、平均初期放電容量が185mAh/g程度と小さく、また10個作製したコイン電池の初期放電容量のバラツキを示す分散σも実施例1〜7に比べて大きくなった。また、比較例2〜5は混合粉末に対するジルコニアボールの質量比が15未満もしくは30を超えていたため、平均初期放電容量が小さく、分散も大きくなった。また、比較例6は遊星運動式混練機の混合時の公転回転数が400rpmを超えていたため、平均初期放電容量が小さく、分散も大きくなった。以上の結果から、本発明の要件を満たす方法で正極膜を作製することで電池特性の測定精度を向上させることが可能であることが分かる。 As can be seen from Table 1 above, in Examples 1 to 7, since the raw materials for the positive electrode film were weighed and produced in an atmosphere with an absolute humidity of 1.2 g / m 3 or less, all of the average initial discharge capacities were 195 mAh / g or more. It became. On the other hand, in Comparative Example 1, since the raw material for the positive electrode film was weighed and produced in an atmosphere exceeding the absolute humidity of 1.2 g / m 3 , the average initial discharge capacity was as small as about 185 mAh / g, and 10 The dispersion σ indicating the variation in the initial discharge capacity of the manufactured coin battery was also larger than in Examples 1-7. In Comparative Examples 2 to 5, since the mass ratio of the zirconia balls to the mixed powder was less than 15 or more than 30, the average initial discharge capacity was small and the dispersion was also large. In Comparative Example 6, since the revolution speed at the time of mixing in the planetary kneader exceeded 400 rpm, the average initial discharge capacity was small and the dispersion was also large. From the above results, it can be seen that the measurement accuracy of the battery characteristics can be improved by producing the positive electrode film by a method satisfying the requirements of the present invention.

1:円形正極膜
2:円形負極膜
3:セパレーター
4:正極缶
5:負極缶
6:ガスケット
7:ウェーブワッシャー
1: Circular positive electrode film 2: Circular negative electrode film 3: Separator 4: Positive electrode can 5: Negative electrode can 6: Gasket 7: Wave washer

Claims (3)

リチウムイオンを吸脱蔵可能な正極活物質からなる第1粉末と、少なくとも導電助剤及び結着剤を含んだ第2粉末とを、該第1粉末及び第2粉末の合計1質量部に対して15〜30質量部のセラミックボールと共に樹脂製の密閉容器に装入し、公転側の回転数100〜400rpm、自転比1/3の遠心遊星運動式混練機を用いて混合する混合工程と、前記混合工程で得られた混合粉末を成型して正極膜を製造する成型工程とからなるリチウムイオン二次電池用正極膜の製造方法であって、前記の混合工程及び成型工程を絶対湿度1.2g/m以下の雰囲気下で行うことを特徴とするリチウムイオン二次電池用正極膜の製造方法。 A first powder made of a positive electrode active material capable of absorbing and desorbing lithium ions, and a second powder containing at least a conductive additive and a binder, with respect to a total of 1 part by mass of the first powder and the second powder Mixing with a centrifugal planetary motion kneader having a rotation speed of 100 to 400 rpm and a rotation ratio of 1/3, with a ceramic ball of 15 to 30 parts by mass in a sealed container made of resin, A method for producing a positive electrode film for a lithium ion secondary battery comprising forming a mixed powder obtained in the mixing step to produce a positive electrode film, wherein the mixing step and the forming step are performed with an absolute humidity of 1. The manufacturing method of the positive electrode film | membrane for lithium ion secondary batteries characterized by performing in 2 g / m < 3 > or less atmosphere. 前記密閉可能な樹脂製容器がミルポッドであることを特徴とする、請求項1に記載のリチウムイオン二次電池用正極膜の製造方法。   The method for producing a positive electrode film for a lithium ion secondary battery according to claim 1, wherein the sealable resin container is a mill pod. 前記成型工程は、前記混合粉末を金属製の金型に装入してプレス成型することを特徴とする、請求項1又は2に記載のリチウムイオン二次電池用正極膜の製造方法。   3. The method for producing a positive electrode film for a lithium ion secondary battery according to claim 1, wherein in the molding step, the mixed powder is inserted into a metal mold and press-molded. 4.
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JP2013093171A (en) * 2011-10-25 2013-05-16 Mitsubishi Chemicals Corp Positive electrode for lithium secondary battery and lithium secondary battery using the same
JP2014103107A (en) * 2012-10-26 2014-06-05 Sumitomo Metal Mining Co Ltd Positive electrode for nonaqueous electrolyte secondary battery and method for manufacturing nonaqueous electrolyte secondary battery using the same
JP2016032143A (en) * 2014-07-28 2016-03-07 長野日本無線株式会社 Communication terminal and data collection system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11135121A (en) * 1997-10-27 1999-05-21 Toray Ind Inc Manufacture of mix for electrode
JP2011192561A (en) * 2010-03-16 2011-09-29 Sanyo Electric Co Ltd Manufacturing method for nonaqueous electrolyte secondary battery
JP2013093171A (en) * 2011-10-25 2013-05-16 Mitsubishi Chemicals Corp Positive electrode for lithium secondary battery and lithium secondary battery using the same
JP2014103107A (en) * 2012-10-26 2014-06-05 Sumitomo Metal Mining Co Ltd Positive electrode for nonaqueous electrolyte secondary battery and method for manufacturing nonaqueous electrolyte secondary battery using the same
JP2016032143A (en) * 2014-07-28 2016-03-07 長野日本無線株式会社 Communication terminal and data collection system

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