JP2011029136A - Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery - Google Patents
Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery Download PDFInfo
- Publication number
- JP2011029136A JP2011029136A JP2009271888A JP2009271888A JP2011029136A JP 2011029136 A JP2011029136 A JP 2011029136A JP 2009271888 A JP2009271888 A JP 2009271888A JP 2009271888 A JP2009271888 A JP 2009271888A JP 2011029136 A JP2011029136 A JP 2011029136A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- active material
- current collector
- secondary battery
- electrode active
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
Abstract
Description
本発明は、特に有機ラジカル化合物を含む電極活物質を使用した二次電池用電極、二次電池、及び二次電池用電極の製造方法に関するものである。 TECHNICAL FIELD The present invention relates to a secondary battery electrode, a secondary battery, and a method for producing a secondary battery electrode, particularly using an electrode active material containing an organic radical compound.
携帯電話、ノートパソコン、ハイブリッド電気自動車などの市場拡大に伴い、小型で高容量、高出力の二次電池が求められている。 Along with the market expansion of mobile phones, notebook computers, hybrid electric vehicles, etc., there is a demand for secondary batteries with small size, high capacity and high output.
そして、このような要求に応えるべく、リチウムイオン等のアルカリ金属イオンを荷電担体とし、その電荷授受に伴う電気化学反応を利用した二次電池が開発されている。特に、出力密度の大きなリチウムイオン二次電池は、現在では広く普及している。 In response to such demands, secondary batteries have been developed that use an alkali metal ion such as lithium ion as a charge carrier and use an electrochemical reaction associated with the charge exchange. In particular, lithium ion secondary batteries with a high output density are now widely used.
二次電池の構成要素のうち電極活物質は、充電反応、放電反応という電池電極反応に直接寄与する物質であり、二次電池の中心的役割を有する。すなわち、電池電極反応は、電解質中に配された電極と電気的に接続された電極活物質に電圧を印加することにより、電子の授受を伴って生じる反応であり、電池の充放電時に進行する。したがって、上述したように電極活物質は、二次電池の中心的役割を有する。 Among the constituent elements of the secondary battery, the electrode active material is a substance that directly contributes to a battery electrode reaction such as a charge reaction and a discharge reaction, and has a central role of the secondary battery. That is, the battery electrode reaction is a reaction that occurs with the transfer of electrons by applying a voltage to an electrode active material that is electrically connected to an electrode disposed in the electrolyte, and proceeds during charge and discharge of the battery. . Therefore, as described above, the electrode active material has a central role of the secondary battery.
そして、リチウムイオン二次電池では、正極の電極活物質としてリチウム含有遷移金属酸化物、負極の電極活物質として炭素材料を使用し、これらの電極活物質に対するリチウムイオンの挿入反応、及び脱離反応を利用して充放電を行っている。 In a lithium ion secondary battery, a lithium-containing transition metal oxide is used as the positive electrode active material, a carbon material is used as the negative electrode active material, and lithium ion insertion and desorption reactions with respect to these electrode active materials. Charging and discharging is performed using
しかしながら、上述したリチウムイオン二次電池は、正極におけるリチウムイオンの移動が律速となるため、充放電の速度が制限されるという問題があった。すなわち、リチウムイオン二次電池では電解質や負極に比べて正極の遷移金属酸化物中でのリチウムイオンの移動速度が遅く、このため正極での電池反応速度が律速となって充放電速度が制限される。その結果、高出力化や充電時間の短時間化には限界があった。 However, the lithium ion secondary battery described above has a problem in that the speed of charging and discharging is limited because the movement of lithium ions in the positive electrode is rate-limiting. In other words, in lithium ion secondary batteries, the migration rate of lithium ions in the transition metal oxide of the positive electrode is slower than that of the electrolyte and negative electrode, which limits the battery reaction rate at the positive electrode and limits the charge / discharge rate. The As a result, there are limits to increasing the output and shortening the charging time.
そこで、このような課題を解決すべく、近年、有機化合物を正極の電極活物質とする二次電池が提案されている。このような二次電池には有機ラジカル化合物を利用したものや有機硫黄化合物を利用したものがあり、研究開発が盛んにおこなわれている。 Therefore, in order to solve such problems, in recent years, secondary batteries using an organic compound as a positive electrode active material have been proposed. Such secondary batteries include those using organic radical compounds and those using organic sulfur compounds, and research and development have been actively conducted.
有機ラジカル化合物は、電子軌道の最外殻に不対電子であるラジカルを有している。そして、このラジカルは一般には反応性に富んだ化学種であり、周囲の物質との相互作用によって、ある程度の寿命を持って消失するものが多い。しかしながら、共鳴効果や立体障害、溶媒和の状態によっては安定したものとなる。 The organic radical compound has a radical which is an unpaired electron in the outermost shell of the electron orbit. These radicals are generally reactive chemical species, and many of them disappear with a certain lifetime due to interaction with surrounding substances. However, it becomes stable depending on the resonance effect, steric hindrance, and solvation state.
そして、ラジカルは反応速度が速いので、安定なラジカルの酸化還元反応を利用して充放電を行うことにより、充電時間を短時間で完了させることが可能となる。 Since radicals have a high reaction rate, the charging time can be completed in a short time by charging and discharging using a stable oxidation-reduction reaction of radicals.
例えば特許文献１には、ニトロキシルラジカル化合物、オキシラジカル化合物、及び窒素原子にラジカルを有する窒素ラジカル化合物を使用した二次電池用の電極活物質が開示されている。この特許文献１では、ラジカルとして安定性の高いニトロキシルラジカルを使用した実施例が記載されている。特許文献１ではニトロキシルラジカル化合物を含む電極層を正極とし、リチウム貼り合わせ銅箔を負極として二次電池を作製し、繰り返し充放電したところ、１０サイクル以上にわたって充放電可能であることが記載されている。 For example, Patent Document 1 discloses an electrode active material for a secondary battery using a nitroxyl radical compound, an oxy radical compound, and a nitrogen radical compound having a radical at a nitrogen atom. In Patent Document 1, an example in which a highly stable nitroxyl radical is used as a radical is described. Patent Document 1 describes that a secondary battery is manufactured using an electrode layer containing a nitroxyl radical compound as a positive electrode and a lithium-bonded copper foil as a negative electrode, and repeatedly charged and discharged, and can be charged and discharged over 10 cycles or more. ing.
しかしながら、有機ラジカル化合物を電極活物質とする電極は、体積当たりの活物質含有量が小さい。したがって、容量密度や出力密度などは質量当たりでは大きくても、体積当たりになると大幅に低下するという問題点があった。これは電極活物質である有機ラジカル化合物自体が絶縁性であるため導電助剤を多量に含有させる必要があることと、有機ラジカル化合物の比重も遷移金属酸化物に比べて小さいことが主な理由である。 However, an electrode using an organic radical compound as an electrode active material has a small active material content per volume. Accordingly, there is a problem that the capacity density, the power density, and the like are large per mass, but are greatly reduced per volume. The main reason for this is that the organic radical compound itself, which is the electrode active material, is insulative, and therefore it is necessary to contain a large amount of conductive assistant, and the specific gravity of the organic radical compound is also smaller than that of the transition metal oxide. It is.
ところで、リチウムイオン二次電池では塗工した電極を加圧する電極プレスが行われている。その結果、電極の比重が増加して容量密度が増大するばかりでなく、電極表面の平坦性が改善する効果や、導電助剤同士や導電助剤と集電体である電極箔との接触が改善して内部抵抗が低減するという効果が得られている。しかしながら、有機ラジカル電池ではこのような電極プレスは適用されていない。有機化合物の場合は固体としての機械的強度がコバルト酸リチウムのような無機の電極活物質に比べて小さい。特に高分子等の場合には変形を伴う圧密化が起こりやすいため、電解質を保持するための電極内の空隙が失われる。このような圧密化した電極では充放電反応の進行が制限され、容量出現率や出力密度の低下につながる。そのため、有機ラジカル電池に関しては、電極プレスの効果や、それによって得られた電池の性質の報告はなされていなかったと考えられる。 By the way, in the lithium ion secondary battery, an electrode press that pressurizes the coated electrode is performed. As a result, not only does the specific gravity of the electrode increase and the capacity density increases, but also the effect of improving the flatness of the electrode surface and the contact between the conductive assistants and between the conductive assistant and the electrode foil as the current collector are present. The effect of improving and reducing the internal resistance is obtained. However, such an electrode press is not applied to the organic radical battery. In the case of an organic compound, the mechanical strength as a solid is lower than that of an inorganic electrode active material such as lithium cobalt oxide. In particular, in the case of a polymer or the like, consolidation accompanied by deformation is likely to occur, so that voids in the electrode for holding the electrolyte are lost. Such a consolidated electrode limits the progress of the charge / discharge reaction, leading to a decrease in capacity appearance rate and output density. Therefore, regarding the organic radical battery, it is considered that the effect of the electrode press and the properties of the battery obtained thereby have not been reported.
以上述べたように電極プレスは容量密度や出力密度を改善する方法として期待されているが、通常の有機ラジカル電池では効果が得られていないというのが現状である。 As described above, the electrode press is expected as a method for improving the capacity density and the output density, but the current situation is that the effect is not obtained in a normal organic radical battery.
このような状況下において、本件発明者は、有機ラジカル化合物を電極活物質とする二次電池用電極において、特定の構成を選択することで、電極プレスが可能となり、高出力の二次電池用電極、及び電池が得られることを見出した。 Under such circumstances, the present inventors have made it possible to press an electrode by selecting a specific configuration in an electrode for a secondary battery using an organic radical compound as an electrode active material, and for a high-power secondary battery. It has been found that an electrode and a battery can be obtained.
本発明はこのような事情に鑑みてなされたものであって、有機ラジカル化合物を電極活物質とする電極の電極プレスを可能とし、高出力で内部抵抗の低い二次電池用電極、二次電池を提供することを目的とする。 The present invention has been made in view of such circumstances, and enables an electrode press of an electrode using an organic radical compound as an electrode active material, and has a high output and a low internal resistance, a secondary battery electrode, and a secondary battery The purpose is to provide.
本発明に係る二次電池用電極は、電極集電体と、有機ラジカル化合物を含む電極活物質と粒子状の導電助剤とを含み、前記電極集電体の一方の主面上に形成された電極活物質層と、を有する二次電池用電極であって、前記電極活物質層における電極集電体側の密度が前記電極集電体側と反対側の密度に比べて大きいことを特徴としている。 An electrode for a secondary battery according to the present invention includes an electrode current collector, an electrode active material containing an organic radical compound, and a particulate conductive additive, and is formed on one main surface of the electrode current collector. An electrode active material layer, wherein the density of the electrode active material layer on the electrode current collector side is higher than the density on the side opposite to the electrode current collector side. .
本発明者は、電極活物質層に有機ラジカル化合物を含んでいる場合に、粒子状の導電助剤を選択することで、電極プレスを行い高出力で内部抵抗の低い二次電池が得られることを見出した。また、本発明では、電極活物質層における電極集電体側の密度が、電極集電体側と反対側の密度に比べて大きい。かかる場合には、電極集電体側にある電極活物質の量が多いため、内部抵抗が小さく、大電流で放電した場合にも電圧降下が小さな、高出力に適した電池となる。 When the present inventor includes an organic radical compound in the electrode active material layer, a secondary battery having high output and low internal resistance can be obtained by performing electrode pressing by selecting a particulate conductive aid. I found. Moreover, in this invention, the density by the side of the electrode collector in an electrode active material layer is large compared with the density by the side opposite to the electrode collector. In such a case, since the amount of the electrode active material on the side of the electrode current collector is large, the battery has a low internal resistance and a small voltage drop even when discharged with a large current, and is a battery suitable for high output.
また、本発明では、前記電極活物質層における前記電極集電体側の密度が０．８ｇ／ｃｍ3以上であることを特徴としている。 In the present invention, the density of the electrode active material layer on the electrode current collector side is 0.8 g / cm 3 or more.
かかる場合には、電極内部の密度との差が大きく、内部抵抗を低減する効果がより顕著である。 In such a case, the difference from the density inside the electrode is large, and the effect of reducing the internal resistance is more remarkable.
また、本発明では、前記有機ラジカル化合物が２，２，６，６−テトラメチルピペリジノキシラジカル構造を含む分子を含むことを特徴としている。 In the present invention, the organic radical compound includes a molecule containing a 2,2,6,6-tetramethylpiperidinoxy radical structure.
かかる場合には、充放電反応が安定である二次電池用電極を提供することができる。 In such a case, it is possible to provide an electrode for a secondary battery in which the charge / discharge reaction is stable.
また、本発明は、前記二次電池用電極からなる正極と、負極と、電解質と、を少なくとも備える二次電池にも向けられる。 The present invention is also directed to a secondary battery comprising at least a positive electrode made of the secondary battery electrode, a negative electrode, and an electrolyte.
また、本発明に係る二次電池用電極の製造方法は、電極集電体を用意する工程と、有機ラジカル化合物を含む電極活物質と、粒子状の導電助剤と、を含む電極活物質スラリーを作製する工程と、前記電極活物質スラリーを前記電極集電体の一方の主面に塗工して電極活物質層を形成する工程と、前記電極活物質層を１２０℃以上の温度でプレスする工程と、を備えることを特徴としている。 Moreover, the manufacturing method of the electrode for secondary batteries which concerns on this invention is the electrode active material slurry containing the process of preparing an electrode electrical power collector, the electrode active material containing an organic radical compound, and a particulate-form conductive support agent. Forming the electrode active material layer by coating the electrode active material slurry on one main surface of the electrode current collector, and pressing the electrode active material layer at a temperature of 120 ° C. or higher. And a step of performing.
かかる場合には、高出力の二次電池用電極が製造可能となる。 In such a case, a high output secondary battery electrode can be manufactured.
本発明では、電極活物質層における電極集電体側の密度が、電極集電体側と反対側の密度に比べて大きいことを特徴としている。かかる場合には、電極集電体側にある電極活物質の量が多いため、内部抵抗が小さく、大電流で放電した場合にも電圧降下が小さな、高出力に適した電池となる。 The present invention is characterized in that the density on the electrode current collector side in the electrode active material layer is higher than the density on the side opposite to the electrode current collector side. In such a case, since the amount of the electrode active material on the side of the electrode current collector is large, the battery has a low internal resistance and a small voltage drop even when discharged with a large current, and is a battery suitable for high output.
以下において、本発明を実施するための形態について説明する。 Hereinafter, modes for carrying out the present invention will be described.
図１に、本発明に係る二次電池用電極の断面図を示す。本発明の二次電池用電極２０は、電極集電体１５と、有機ラジカル化合物を含む電極活物質と粒子状の導電助剤とを含み、前記電極集電体の一方の主面上に形成された電極活物質層１６と、を有する。そして、電極活物質層１６における電極集電体側１６ｂの密度が前記電極集電体側と反対側１６ａの密度に比べて大きいことを特徴としている。 FIG. 1 shows a cross-sectional view of a secondary battery electrode according to the present invention. The electrode 20 for a secondary battery according to the present invention includes an electrode current collector 15, an electrode active material containing an organic radical compound, and a particulate conductive additive, and is formed on one main surface of the electrode current collector. Electrode active material layer 16. The electrode active material layer 16 is characterized in that the density on the electrode current collector side 16b is higher than the density on the side 16a opposite to the electrode current collector side.
本発明において電極集電体は特に限定されないが、例えばＡｌが挙げられる。また、Ａｌ表面を改質したものや、Ａｌ−Ｍｎ合金等も含まれる。 In the present invention, the electrode current collector is not particularly limited, and examples thereof include Al. Also included are those obtained by modifying the Al surface and Al-Mn alloys.
また、本発明において導電助剤は導電性を有する材料であれば特に限定されず、炭素材料を用いることが好ましい。例えば、グラファイト、カーボンブラック、アセチレンブラック等の炭素質微粒子、気相成長炭素繊維（ＶＧＣＦ）、カーボンナノチューブ、カーボンナノホーン等の炭素繊維、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセチレン、ポリアセン等の導電性高分子やフラーレン、金属粉末などが利用できる。 In the present invention, the conductive assistant is not particularly limited as long as it is a conductive material, and a carbon material is preferably used. For example, carbonaceous fine particles such as graphite, carbon black, and acetylene black, carbon fibers such as vapor grown carbon fiber (VGCF), carbon nanotube, and carbon nanohorn, conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene, Fullerene, metal powder, etc. can be used.
また、プレスの点から粒子状の導電助剤が好ましい。このような粒子状の導電助剤としては、Ｃ６０やＣ７０などのフラーレン類、天然黒鉛もしくは人造黒鉛を含有する黒鉛系炭素質物、石炭系コークス、石油系コークス、ファーネスブラック、チャンネルブラック、アセチレンブラック、サーマルブラックなどの有機物の熱分解物などが挙げられる。 In addition, a particulate conductive aid is preferable from the viewpoint of pressing. Examples of such particulate conductive aids include fullerenes such as C60 and C70, graphite-based carbonaceous materials containing natural graphite or artificial graphite, coal-based coke, petroleum-based coke, furnace black, channel black, acetylene black, Examples include thermal decomposition products of organic substances such as thermal black.
また、本発明では導電助剤を２種類以上混合して用いることもできる。尚、導電助剤の電極中の含有率も特に限定されないが、１０〜８０質量％が望ましい。 In the present invention, two or more kinds of conductive assistants can be mixed and used. In addition, although the content rate in the electrode of a conductive support agent is not specifically limited, 10-80 mass% is desirable.
本発明において、粒子状の炭化水素とは繊維状炭化水素と対比されるもので、長辺の長さと短辺の長さの比、すなわちアスペクト比が概ね５以下の形状のものを言う。本発明者らの検討によれば、繊維状の炭化水素を導電助剤とする場合には電極プレスを行うとプレス温度に依らず、容量や出力が大幅に低下する。繊維状炭素は塗工表面に偏在化しやすく、さらに、電極プレスを行うと表面に電極活物質を含まない緻密な繊維状炭素の層が形成されるために、電解質の浸透が阻害されるためと考えられるが、詳細は不明である。 In the present invention, particulate hydrocarbons are contrasted with fibrous hydrocarbons and refer to those having a shape in which the ratio of the length of the long side to the length of the short side, that is, the aspect ratio is approximately 5 or less. According to the study by the present inventors, when a fibrous hydrocarbon is used as a conductive additive, the capacity and output are greatly reduced regardless of the pressing temperature when the electrode is pressed. Fibrous carbon tends to be unevenly distributed on the coating surface, and when electrode pressing is performed, a dense fibrous carbon layer that does not contain an electrode active material is formed on the surface. Though possible, details are unknown.
また、本発明において電極の密度は特に限定されないが、発明の効果の点から電極集電体側の密度が０．８ｇ／ｃｍ3以上であることが好ましい。一般に、有機ラジカル化合物とアセチレンブラックなどの導電助剤を含む電極の密度は、電極スラリーから塗工した場合や、乾燥粉末を加圧成型して作成した場合には、０．４〜０．６ｇ／ｃｍ3である。したがって、電極集電体側の密度が０．８ｇ／ｃｍ3以下では電極内部との密度の差が小さく、内部抵抗を低減する効果が得られない。 In the present invention, the density of the electrode is not particularly limited, but the density on the electrode current collector side is preferably 0.8 g / cm 3 or more from the viewpoint of the effects of the invention. In general, the density of an electrode containing an organic radical compound and a conductive auxiliary agent such as acetylene black is 0.4 to 0.6 g when applied from an electrode slurry or formed by pressing a dry powder. / Cm 3 . Therefore, when the density on the electrode current collector side is 0.8 g / cm 3 or less, the difference in density from the inside of the electrode is small, and the effect of reducing the internal resistance cannot be obtained.
また、本発明において有機ラジカル化合物のラジカル基は特に限定されない。例えば、ピペリジノキシラジカル基（ａ）、プロキシラジカル基（ｂ）、ピロリノキシラジカル基（ｃ）、ジ−ｔｅｒｔ−ブチルニトロキシラジカル基（ｄ）、アザアダマンチルラジカル基（ｅ）、トリメチルジアザアダマンチルラジカル基（ｆ）、架橋脂環式化合物ニトロキシラジカル基（ｇ）、芳香族ニトロキシラジカル基（ｈ）〜（ｌ）などが挙げられる。 In the present invention, the radical group of the organic radical compound is not particularly limited. For example, piperidinoxy radical group (a), proxy radical group (b), pyrrolinoxy radical group (c), di-tert-butyl nitroxy radical group (d), azaadamantyl radical group (e), trimethyl Examples thereof include a diazaadamantyl radical group (f), a bridged alicyclic compound nitroxy radical group (g), and aromatic nitroxy radical groups (h) to (l).
また、本発明において有機ラジカル化合物は特に限定されない。例えば、各種のニトロキシラジカル、窒素ラジカル、酸素ラジカル、チオアミニルラジカル、硫黄ラジカル、ホウ素ラジカル等が用いられるが、充放電反応が安定であることから特に２，２，６，６−テトラメチルピペリジノキシラジカル構造を含む分子からなる化合物が好ましい。このような、２，２，６，６−テトラメチルピペリジノキシラジカル構造を含む分子としては、例えば［化５］〜［化１０］で表わされる高分子化合物やこれらを繰り返し単位の一部とする共重合体などが挙げられる。 In the present invention, the organic radical compound is not particularly limited. For example, various nitroxy radicals, nitrogen radicals, oxygen radicals, thioaminyl radicals, sulfur radicals, boron radicals and the like are used, but 2,2,6,6-tetramethyl is particularly preferred because of its stable charge / discharge reaction. A compound consisting of a molecule containing a piperidinoxy radical structure is preferred. Examples of such a molecule containing a 2,2,6,6-tetramethylpiperidinoxy radical structure include a polymer compound represented by [Chemical Formula 5] to [Chemical Formula 10] and a part of these repeating units. And the like.
本発明に係る二次電池用電極の製造方法は、電極集電体を用意する工程と、有機ラジカル化合物を含む電極活物質と、粒子状の導電助剤と、を含む電極活物質スラリーを作製する工程と、前記電極活物質スラリーを前記電極集電体の一方の主面に塗工して電極活物質層を形成する工程と、前記電極活物質層を１２０℃以上の温度でプレスする工程と、を備えることを特徴としている。図２にその概略図を示す。 The manufacturing method of the electrode for secondary batteries which concerns on this invention produces the electrode active material slurry containing the process of preparing an electrode electrical power collector, the electrode active material containing an organic radical compound, and a particulate-form conductive support agent. A step of coating the electrode active material slurry on one main surface of the electrode current collector to form an electrode active material layer, and a step of pressing the electrode active material layer at a temperature of 120 ° C. or higher. It is characterized by providing these. The schematic is shown in FIG.
まず、図２（ａ）に示すように、電極集電体１５を用意する。 First, as shown in FIG. 2A, an electrode current collector 15 is prepared.
次に、図示していないが、電極活物質を導電助剤、及び結合剤と共に混合し、有機溶剤、もしくは水を加えて電極活物質スラリーを作製する。 Next, although not shown, an electrode active material is mixed with a conductive additive and a binder, and an organic solvent or water is added to prepare an electrode active material slurry.
次に、図２（ｂ）に示すように、電極活物質スラリーを電極集電体の一方の主面に塗工して電極活物質層１６を形成する。 Next, as shown in FIG. 2B, the electrode active material slurry is applied to one main surface of the electrode current collector to form the electrode active material layer 16.
そして、図２（ｃ）に示すように、電極活物質層１６をプレス５０でプレスする。図は二軸プレスの例である。本発明において、プレスの方法は特に限定されず、一軸プレスやロールプレス、あるいは静水圧を用いて加圧する方法などで行われ、一般には５０ＭＰａ以上で効果が得られる。また、圧力が３００ＭＰａを超える場合には全体が押しつぶされて本発明の効果が得られないため、圧力は３００ＭＰａ以下が望ましい。 Then, the electrode active material layer 16 is pressed with a press 50 as shown in FIG. The figure is an example of a biaxial press. In the present invention, the pressing method is not particularly limited, and the pressing is performed by a uniaxial press, a roll press, a method of applying pressure using hydrostatic pressure, or the like, and generally an effect is obtained at 50 MPa or more. Further, when the pressure exceeds 300 MPa, the whole is crushed and the effect of the present invention cannot be obtained, so the pressure is desirably 300 MPa or less.
本発明者らの検討によれば、有機ラジカル化合物を含む電極活物質と粒子状の導電助剤と、を含む電極活物質スラリーを塗工した電極は、どの部分でも密度が０．４〜０．６ｇ／ｃｍ3であるが、電極プレスを行うとプレス温度によって異なる構造が出現する。プレス温度が１２０℃以上では、電極活物質層の電極集電体側の密度が電極集電体側と反対側の密度に比べて大きくなる。逆に、１２０℃より低い温度では、電極集電体側の密度が電極集電体側と反対側の密度に比べて小さくなる。従って、１２０℃以上で電極プレスを行うことにより、電極集電体側の電極活物質の割合が大きくなり、内部抵抗を低減しやすい構造とすることができる。 According to the study by the present inventors, an electrode coated with an electrode active material slurry containing an electrode active material containing an organic radical compound and a particulate conductive additive has a density of 0.4 to 0 in any part. Although it is .6 g / cm 3 , when an electrode press is performed, a different structure appears depending on the press temperature. When the pressing temperature is 120 ° C. or higher, the density of the electrode active material layer on the electrode current collector side is higher than the density on the side opposite to the electrode current collector side. On the other hand, at a temperature lower than 120 ° C., the density on the electrode current collector side becomes smaller than the density on the side opposite to the electrode current collector side. Therefore, by performing electrode pressing at 120 ° C. or higher, the ratio of the electrode active material on the electrode current collector side is increased, and a structure in which the internal resistance can be easily reduced can be obtained.
１２０℃よりも低い温度でプレスした場合には、電極活物質層の変位は表面ほど大きくなる。したがって、電極集電体側の密度が、電極集電体側と反対側（すなわちプレスされた表面）の密度に比べて小さくなると考えられる。 When the pressing is performed at a temperature lower than 120 ° C., the displacement of the electrode active material layer becomes larger toward the surface. Therefore, the density on the electrode current collector side is considered to be smaller than the density on the side opposite to the electrode current collector side (that is, the pressed surface).
一方、１２０℃以上の温度でプレスした場合には、電極活物質層も多少流動的になり、全体が一様にプレスされると考えられる。そして、プレス時の圧力を取り去る際に、プレスされた表面の変位が緩和される。したがって、電極集電体側の密度が、電極集電体側と反対側（すなわちプレスされた表面）の密度に比べて大きくなると考えられる。 On the other hand, when it is pressed at a temperature of 120 ° C. or higher, the electrode active material layer is also somewhat fluid, and the whole is considered to be pressed uniformly. And when removing the pressure at the time of a press, the displacement of the pressed surface is relieved. Therefore, it is considered that the density on the electrode current collector side is larger than the density on the side opposite to the electrode current collector side (that is, the pressed surface).
本発明ではプレス温度の上限は特に限定されないが、好ましくは１７０℃以下の温度で行われる。１７０℃より高い温度の場合には、結合剤の融点に近づき、電極プレスを行っても、結合剤がうまく機能しないと考えられるためである。 In the present invention, the upper limit of the press temperature is not particularly limited, but is preferably performed at a temperature of 170 ° C. or lower. This is because when the temperature is higher than 170 ° C., the binder approaches the melting point of the binder, and it is considered that the binder does not function well even when electrode pressing is performed.
本発明において電極の密度は、電極集電体と、電極集電体上に形成した電極活物質層の質量と、面積および厚さから求めた体積から全体の値が求められる。また、電極集電体側の密度は、例えば塗工した電極を表面から所定の深さまで切削加工し、残った電極の質量と体積から求めることができる。本発明において、電極集電体側と電極集電体側と反対側とは、電極の厚さの中心の位置で分けている。 In the present invention, the overall density of the electrode density is determined from the volume determined from the electrode current collector, the mass of the electrode active material layer formed on the electrode current collector, the area, and the thickness. The density on the electrode current collector side can be obtained from the mass and volume of the remaining electrode after cutting the coated electrode from the surface to a predetermined depth, for example. In the present invention, the electrode current collector side and the electrode current collector side opposite to the electrode current collector side are divided at the center position of the electrode thickness.
一方、電極集電体側と反対側の密度は全体の密度と先に求めた電極集電体側の密度と体積の割合から求めることができる。また、電極断面を走査型電子顕微鏡などで観察し、空隙率などから便宜的に求めることもできる。 On the other hand, the density on the side opposite to the electrode current collector side can be determined from the overall density and the ratio of the density and volume on the electrode current collector previously determined. Further, the electrode cross section can be observed with a scanning electron microscope or the like, and can be obtained for convenience from the porosity.
次に、二次電池用電極を使用した二次電池について記述する。 Next, a secondary battery using the secondary battery electrode will be described.
図３は、本発明に係る二次電池の一実施の形態としてのコイン型二次電池を示す断面図である。本実施の形態では、本発明の二次電池用電極を正極として使用している。 FIG. 3 is a cross-sectional view showing a coin-type secondary battery as an embodiment of the secondary battery according to the present invention. In the present embodiment, the secondary battery electrode of the present invention is used as a positive electrode.
電池缶１は、正極ケース２と負極ケース３とを有し、該正極ケース２及び負極ケース３は、いずれも円盤状の薄板形状に形成されている。そして、正極ケース２の底部中央には、正極の電極集電体に形成された電極集電体側の密度が電極集電体と反対側の密度に比べて大きい電極活物質層を有する正極４が配されている。そして、正極４上には微多孔膜、織布、不織布などの多孔性のシートまたはフィルムで形成されたセパレータ５が積層され、さらにセパレータ５には負極６が積層されている。負極６としては、例えば、銅箔にリチウムの金属箔を重ね合わせたものや、黒鉛やハードカーボン等のリチウム吸蔵材料を銅箔に塗布したものを使用することができる。負極６には金属からなる負極集電体７が積層されるとともに、該負極集電体７には金属製ばね８が載置されている。そして、電解質９が内部空間に充填されると共に、負極ケース３は金属製ばね８の付勢力に抗して正極ケース２に固着され、ガスケット１０を介して封止されている。 The battery can 1 has a positive electrode case 2 and a negative electrode case 3, and both the positive electrode case 2 and the negative electrode case 3 are formed in a disk-like thin plate shape. In the center of the bottom of the positive electrode case 2, there is a positive electrode 4 having an electrode active material layer in which the density of the electrode current collector formed on the positive electrode current collector is larger than the density on the side opposite to the electrode current collector. It is arranged. A separator 5 formed of a porous sheet or film such as a microporous film, a woven fabric, or a nonwoven fabric is laminated on the positive electrode 4, and a negative electrode 6 is laminated on the separator 5. As the negative electrode 6, for example, a copper foil laminated with a lithium metal foil or a lithium foil occlusion material such as graphite or hard carbon applied to the copper foil can be used. A negative electrode current collector 7 made of metal is laminated on the negative electrode 6, and a metal spring 8 is placed on the negative electrode current collector 7. The electrolyte 9 is filled in the internal space, and the negative electrode case 3 is fixed to the positive electrode case 2 against the urging force of the metal spring 8 and sealed with a gasket 10.
次に、上記二次電池の製造方法の一例を詳述する。 Next, an example of a method for manufacturing the secondary battery will be described in detail.
まず、正極を形成する。例えば、電極活物質を導電助剤、及び結合剤と共に混合し、有機溶剤、もしくは水を加えて電極活物質スラリーとし、該電極活物質スラリーを電極集電体上に任意の塗工方法で塗工し、乾燥することにより正極を形成する。 First, a positive electrode is formed. For example, an electrode active material is mixed with a conductive additive and a binder, an organic solvent or water is added to form an electrode active material slurry, and the electrode active material slurry is applied onto the electrode current collector by an arbitrary coating method. The positive electrode is formed by working and drying.
本発明において結合剤は特に限定されるものではなく、ポリエチレン、ポリフッ化ビニリデン、ポリヘキサフルオロプロピレン、ポリテトラフルオロエチレン、ポリエチレンオキサイド、カルボキシメチルセルロース等の各種樹脂を使用することができる。 In the present invention, the binder is not particularly limited, and various resins such as polyethylene, polyvinylidene fluoride, polyhexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, and carboxymethyl cellulose can be used.
また、有機溶剤についても、特に限定されるものではなく、例えば、ジメチルスルホキシド、ジメチルホルムアミド、Ｎ−メチル−２−ピロリドン、プロピレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、γ−ブチロラクトン等の塩基性溶媒、アセトニトリル、テトラヒドロフラン、ニトロベンゼン、アセトン等の非水溶媒、メタノール、エタノール等のプロトン性溶媒等を使用することができる。また、有機溶剤の種類、有機化合物と有機溶剤との配合比、添加剤の種類とその添加量等は、二次電池の要求特性や生産性等を考慮し、任意に設定することができる。 Further, the organic solvent is not particularly limited, and examples thereof include basic solvents such as dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, propylene carbonate, diethyl carbonate, dimethyl carbonate, and γ-butyrolactone, acetonitrile. Nonaqueous solvents such as tetrahydrofuran, nitrobenzene, and acetone, and protic solvents such as methanol and ethanol can be used. Moreover, the kind of organic solvent, the compounding ratio of the organic compound and the organic solvent, the kind of additive and the addition amount thereof can be arbitrarily set in consideration of the required characteristics and productivity of the secondary battery.
次いで、この正極４を電解質９に含浸させて該正極４に前記電解質９を染み込ませ、その後、正極ケース２の底部中央の正極集電体上に正極４を載置する。その後、電解質９を含浸させたセパレータ５を正極４上に積層し、さらに負極６及び負極集電体７を順次積層し、内部空間に電解質９を注入する。そして、負極集電体７上に金属製ばね８を載置すると共に、ガスケット１０を周縁に配し、かしめ機等で負極ケース３を正極ケース２に固着して外装封止することでコイン型二次電池が作製される。 Next, the positive electrode 4 is impregnated in the electrolyte 9 so that the positive electrode 4 is impregnated with the electrolyte 9, and then the positive electrode 4 is placed on the positive electrode current collector at the bottom center of the positive electrode case 2. Thereafter, the separator 5 impregnated with the electrolyte 9 is laminated on the positive electrode 4, the negative electrode 6 and the negative electrode current collector 7 are sequentially laminated, and the electrolyte 9 is injected into the internal space. Then, a metal spring 8 is placed on the negative electrode current collector 7, a gasket 10 is arranged on the periphery, and the negative electrode case 3 is fixed to the positive electrode case 2 with a caulking machine or the like and sealed externally to form a coin type. A secondary battery is produced.
尚、電解質９は、正極４と対向電極である負極６との間に介在して両電極間の荷電担体輸送を行う。このような電解質としては、室温で１０-5〜１０-1Ｓ／ｃｍのイオン伝導度を有するものを使用することができる。例えば、電解質塩を有機溶剤に溶解させた電解液を使用することができる。ここで、電解質塩としては、例えば、ＬｉＰＦ6、ＬｉＣｌＯ4、ＬｉＢＦ4、ＬｉＣＦ3ＳＯ3、Ｌｉ（ＣＦ3ＳＯ2）2、Ｌｉ（Ｃ2Ｆ5ＳＯ2）2Ｎ、Ｌｉ（ＣＦ3ＳＯ2）3Ｃ、Ｌｉ（Ｃ2Ｆ5ＳＯ2）3Ｃ等を使用することができる。 The electrolyte 9 is interposed between the positive electrode 4 and the negative electrode 6 which is a counter electrode, and transports charge carriers between the two electrodes. As such an electrolyte, an electrolyte having an ionic conductivity of 10 −5 to 10 −1 S / cm at room temperature can be used. For example, an electrolytic solution in which an electrolyte salt is dissolved in an organic solvent can be used. Here, as the electrolyte salt, for example, LiPF 6 , LiClO 4 , LiBF 4 , LiCF 3 SO 3 , Li (CF 3 SO 2 ) 2 , Li (C 2 F 5 SO 2 ) 2 N, Li (CF 3 SO 2 ) 3 C, Li (C 2 F 5 SO 2 ) 3 C, or the like can be used.
また、有機溶剤としては、エチレンカーボネート、プロピレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、γ一ブチロラクトン、テトラヒドロフラン、ジオキソラン、スルホラン、ジメチルホルムアミド、ジメチルアセトアミド、Ｎ−メチル−２−ピロリドン等を使用することができる。 As the organic solvent, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, etc. are used. be able to.
また、電解質９には、固体電解質を使用してもよい。固体電解質に用いられる高分子化合物としては、例えば、ポリフッ化ビニリデン、フッ化ビニリデン−ヘキサフルオロプロピレン共重合体、フッ化ビニリデン−エチレン共重合体、フッ化ビニリデン−モノフルオロエチレン共重合体、フッ化ビニリデン−トリフルオロエチレン共重合体、フッ化ビニリデン−テトラフルオロエチレン共重合体、フッ化ビニリデン−ヘキサフルオロプロピレン−テトラフルオロエチレン三元共重合体等のフッ化ビニリデン系重合体、アクリロニトリル−メチルメタクリレート共重合体、アクリロニトリル−メチルアクリレート共重合体、アクリロニトリル−エチルメタクリレート共重合体、アクリロニトリル−エチルアクリレート共重合体、アクリロニトリル−メタクリル酸共重合体、アクリロニトリル−アクリル酸共重合体、アクリロニトリル−ビニルアセテート共重合体等のアクリロニトリル系重合体、さらにはポリエチレンオキサイド、エチレンオキサイド−プロピレンオキサイド共重合体、及びこれらのアクリレート体やメタクリレート体の重合体等を挙げることができる。また、これらの高分子化合物に電解液を含ませてゲル状にしたものを電解質９として使用してもよい。或いは電解質塩を含有させた高分子化合物のみをそのまま電解質９に使用してもよい。 The electrolyte 9 may be a solid electrolyte. Examples of the polymer compound used for the solid electrolyte include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-monofluoroethylene copolymer, and fluoride. Vinylidene fluoride-based polymers such as vinylidene-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and acrylonitrile-methyl methacrylate copolymer Polymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-ethyl methacrylate copolymer, acrylonitrile-ethyl acrylate copolymer, acrylonitrile-methacrylic acid copolymer, acrylonitrile-acrylic Examples thereof include acrylonitrile polymers such as phosphoric acid copolymers, acrylonitrile-vinyl acetate copolymers, polyethylene oxide, ethylene oxide-propylene oxide copolymers, and polymers of these acrylates and methacrylates. it can. In addition, a gel formed by adding an electrolytic solution to these polymer compounds may be used as the electrolyte 9. Alternatively, only the polymer compound containing the electrolyte salt may be used as the electrolyte 9 as it is.
また、上記実施の形態では、コイン型二次電池について説明したが、電池形状は特に限定されるものでないのはいうまでもなく、円筒型、角型、シート型等にも適用できる。また、外装方法も特に限定されず、金属ケースや、モールド樹脂、アルミラミネートフイルム等を使用してもよい。 In the above embodiment, the coin-type secondary battery has been described. However, the battery shape is not particularly limited, and can be applied to a cylindrical type, a square type, a sheet type, and the like. Also, the exterior method is not particularly limited, and a metal case, mold resin, aluminum laminate film, or the like may be used.
また、上記実施の形態では、電極活物質を正極に使用したが、負極に使用するのも有用である。 Moreover, in the said embodiment, although the electrode active material was used for the positive electrode, using it for a negative electrode is also useful.
また、上記実施の形態では、電極活物質を二次電池に使用した場合について述べたが、一次電池にも使用することが可能である。 Moreover, although the case where the electrode active material was used for a secondary battery was described in the said embodiment, it can be used also for a primary battery.
次に、本発明の実施例を具体的に説明する。尚、以下に示す実施例は一例であり、本発明は下記の実施例に限定されるものではない。 Next, examples of the present invention will be specifically described. In addition, the Example shown below is an example and this invention is not limited to the following Example.
〔実験例１〕
電極活物質としてポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）６００ｍｇ、導電助剤として平均粒径３６ｎｍの電気化学工業株式会社製デンカブラックプレス品３００ｍｇ、および結合剤として株式会社クレハ製ポリフッ化ビニリデン（ＫＦ−１７００）１００ｍｇにＮ−メチル−２−ピロリドンを加え、ホモミキサーを用いて室温で３０分間撹拌した。３０分後、得られた電極活物質スラリーを取り出し、コーターを用いて厚さ１５μｍのＡｌ箔上に塗工して、１２０℃で乾燥させ、厚さ１５０μｍのポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）を電極活物質とする電極を形成した。この厚さ及び質量から求めたこの電極の密度は０．５８であった。
[Experimental Example 1]
600 mg of poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) as an electrode active material, 300 mg of Denka Black Press product manufactured by Denki Kagaku Kogyo Co., Ltd. having an average particle size of 36 nm as a conductive additive, and bonding As an agent, N-methyl-2-pyrrolidone was added to 100 mg of polyvinylidene fluoride (KF-1700) manufactured by Kureha Corporation, and the mixture was stirred at room temperature for 30 minutes using a homomixer. After 30 minutes, the obtained electrode active material slurry was taken out, applied onto a 15 μm thick Al foil using a coater, dried at 120 ° C., and 150 μm thick poly (2,2,6,6). An electrode using -tetramethyl-4-piperidinoxymethacrylate) as an electrode active material was formed. The density of this electrode determined from this thickness and mass was 0.58.
次に、得られた電極を切り出し、圧力を変えながら１２５℃で３０秒間二軸プレスを行った。得られた電極の厚さと厚さから求めた電極全体の密度、および電極を５０％まで切削加工して求めた電極集電体側の密度を表１に示す。 Next, the obtained electrode was cut out and biaxial pressing was performed at 125 ° C. for 30 seconds while changing the pressure. Table 1 shows the density of the entire electrode obtained from the thickness and thickness of the obtained electrode, and the density on the electrode current collector obtained by cutting the electrode to 50%.
次いで、直径１２ｍｍの円形に電極を打ち抜き、電解液に含浸して空隙に減圧（８０％、３０秒）と昇圧を２回繰り返した後、常圧で３０分放置して電解液を染み込ませた。電解液としては、モル濃度が１．０ｍｏｌ／ＬのＬｉＰＦ6（電解質塩）を含有した有機溶剤であるエチレンカーボネート／ジエチルカーボネート混合溶液を使用した。尚、有機溶剤であるエチレンカーボネート／ジエチルカーボネートの混合比率は体積％でエチレンカーボネート：ジエチルカーボネート＝３０：７０であった。この正極をコイン型セルの正極ケース上に載置し、さらに前記電解液を含浸させたポリプロピレン多孔質フィルムからなる厚さ２０μｍのセパレータを前記正極上に積層し、さらに銅箔の両面にリチウムを貼布した負極をセパレータ上に積層した。そして、負極上に集電用の金属ディスクを積層した後、内部空間に電解液を注入し、金属製ばねを載置すると共に、周縁にガスケットを配置した状態で負極ケースを正極ケースに接合し、かしめ機によって外装封止した。これにより、有機ラジカル化合物であるポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）と粒子状の導電助剤とを含む電極活物質層を有する密閉型のコイン型二次電池を作製した。 Next, the electrode was punched out into a circle with a diameter of 12 mm, impregnated with the electrolyte, and reduced in pressure (80%, 30 seconds) and increased twice in the gap, and then allowed to stand at normal pressure for 30 minutes to soak the electrolyte. . As the electrolytic solution, an ethylene carbonate / diethyl carbonate mixed solution, which is an organic solvent containing LiPF 6 (electrolyte salt) having a molar concentration of 1.0 mol / L, was used. In addition, the mixing ratio of ethylene carbonate / diethyl carbonate as an organic solvent was ethylene carbonate: diethyl carbonate = 30: 70 in volume%. This positive electrode was placed on a positive electrode case of a coin-type cell, and a separator having a thickness of 20 μm made of a polypropylene porous film impregnated with the electrolytic solution was laminated on the positive electrode, and lithium was further applied to both sides of the copper foil. The pasted negative electrode was laminated on the separator. Then, after laminating a current collecting metal disk on the negative electrode, the electrolytic solution is injected into the internal space, a metal spring is placed, and the negative electrode case is joined to the positive electrode case with a gasket disposed on the periphery. The exterior was sealed with a caulking machine. Thus, a sealed coin type having an electrode active material layer containing poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate), which is an organic radical compound, and a particulate conductive auxiliary agent A secondary battery was produced.
予備実験として、以上のように作製した二次電池のうち電極プレスをしていない電極を用いたセルを、０．１ｍＡの定電流で電圧４．２Ｖまで充電し、その後、０．１ｍＡの定電流で２．５Ｖまで放電した。その結果、このセルの放電容量は０．５ｍＡｈであることがわかった。 As a preliminary experiment, a cell using an electrode not pressed among the secondary batteries produced as described above was charged to a voltage of 4.2 V with a constant current of 0.1 mA, and then a constant current of 0.1 mA. Discharge to 2.5V with current. As a result, it was found that the discharge capacity of this cell was 0.5 mAh.
この結果に基づいて、作製したセルを６０ｍＡの定電流、すなわち１２０Ｃで充放電試験を行った。ここで、１２０Ｃとは電池を１時間で充放電する電流（１Ｃ）の１２０倍の電流、すなわち３０秒間で充放電する電流を意味する。この１２０Ｃで測定した容量はプレス圧力０ＭＰａ（プレスなし）、５０ＭＰａ、１００ＭＰａ、及び１５０ＭＰａについて、それぞれ０．１２ｍＡｈ、０．３０ｍＡｈ、０．３２ｍＡｈ、０．３５ｍＡｈであった。 Based on this result, the fabricated cell was subjected to a charge / discharge test at a constant current of 60 mA, that is, 120C. Here, 120C means 120 times the current (1C) for charging / discharging the battery in 1 hour, that is, the current for charging / discharging in 30 seconds. The capacities measured at 120C were 0.12 mAh, 0.30 mAh, 0.32 mAh, and 0.35 mAh for press pressures of 0 MPa (no pressing), 50 MPa, 100 MPa, and 150 MPa, respectively.
また、それぞれのセルの交流インピーダンス測定で得られるＣｏｌｅ−Ｃｏｌｅプロットから見積もった電荷移動抵抗はそれぞれ、１０Ω、６．４Ω、６．２Ω、６．４Ωとなり、電極プレスを行ったものは低インピーダンスであることがわかった。 In addition, the charge transfer resistance estimated from the Cole-Cole plot obtained by the AC impedance measurement of each cell is 10Ω, 6.4Ω, 6.2Ω, and 6.4Ω, respectively, and the electrode pressed is low impedance. I found out.
このことから、電極活物質層における電極集電体側の密度が電解質側の密度に比べて大きい、プレス圧５０ＭＰａ以上でプレスした電極は、プレスしていない電極に比べて大電流でも容量低下が少ないことがわかった。 From this, the density of the electrode current collector side in the electrode active material layer is larger than the density on the electrolyte side, and the electrode pressed at a pressing pressure of 50 MPa or more has less capacity reduction even at a large current compared to the unpressed electrode. I understood it.
〔比較例１〕
実験例１のデンカブラックに代えて繊維径１５０ｎｍ、アスペクト比１０〜５００の昭和電工株式会社製ＶＧＣＦ−Ｈを使う以外は実験例１と同様の方法でポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）を含む電極活物質スラリーを作製した。そしてコーターを用いて厚さ１５μｍのＡｌ箔上に塗工して乾燥させ、厚さ１５０μｍのポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）を電極活物質とする電極を形成した。この厚さ及び質量から求めたこの電極の密度は０．５９であった。
[Comparative Example 1]
Poly (2,2,6,6-tetra) in the same manner as in Experimental Example 1 except that VGCF-H manufactured by Showa Denko KK having a fiber diameter of 150 nm and an aspect ratio of 10 to 500 was used instead of Denka Black in Experimental Example 1. An electrode active material slurry containing methyl-4-piperidinoxymethacrylate) was prepared. And it coats on 15-micrometer-thick Al foil using a coater, it is made to dry, 150-micrometer-thick poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) and an electrode active material An electrode to be formed was formed. The density of this electrode determined from this thickness and mass was 0.59.
次に、得られた電極を切り出し、実験例１と同様の方法で電極プレスを行った。得られた電極の厚さ、および厚さから求めた電極全体の密度を表２に示す。 Next, the obtained electrode was cut out and subjected to electrode pressing in the same manner as in Experimental Example 1. Table 2 shows the thickness of the obtained electrode and the density of the entire electrode obtained from the thickness.
次いで、実験例１と同様の方法で電極を打ち抜き、電解液を染み込ませて、有機ラジカル化合物であるポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）と繊維状の導電助剤ＶＧＣＦ−Ｈとを含む電極活物質層を有する密閉型のコイン型二次電池を作製した。 Next, the electrode was punched out in the same manner as in Experimental Example 1, and the electrolyte solution was soaked, and the organic radical compound poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) and fibrous form A sealed coin-type secondary battery having an electrode active material layer containing the conductive assistant VGCF-H was prepared.
予備実験として、作製した二次電池のうち電極プレスをしていない電極を用いたセルを、０．１ｍＡの定電流で電圧４．２Ｖまで充電し、その後、０．１ｍＡの定電流で２．５Ｖまで放電した。その結果、このセルの放電容量は０．５ｍＡｈであることがわかった。 As a preliminary experiment, a cell using an electrode that was not subjected to electrode pressing among the produced secondary batteries was charged to a voltage of 4.2 V with a constant current of 0.1 mA, and then 2. with a constant current of 0.1 mA. Discharged to 5V. As a result, it was found that the discharge capacity of this cell was 0.5 mAh.
この結果に基づいて、実験例１と同様の方法で作製したセルを６０ｍＡの定電流、すなわち１２０Ｃで充放電試験を行った。その結果、５０ＭＰａ、１００ＭＰａ、１５０ＭＰａで電極プレスした条件では、１２０Ｃで測定した容量は０．１ｍＡｈ以下となった。また、１Ｃで測定した容量も０．１ｍＡｈ以下となり、二次電池として動作しないことがわかった。 Based on this result, a cell produced by the same method as in Experimental Example 1 was subjected to a charge / discharge test at a constant current of 60 mA, that is, 120C. As a result, under the conditions where the electrode was pressed at 50 MPa, 100 MPa, and 150 MPa, the capacity measured at 120 C was 0.1 mAh or less. Further, the capacity measured at 1C was 0.1 mAh or less, and it was found that the battery did not operate as a secondary battery.
〔実験例２〕
実験例１のデンカブラックに代えて粒径３９．５μｍのライオン株式会社製ケッチェンブラックＥＣ３００Ｊを使う以外は実験例１と同様の方法でポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）を含む電極活物質スラリーを作製した。そして、コーターを用いて厚さ１５μｍのＡｌ箔上に塗工して乾燥させ、厚さ１５０μｍのポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）を電極活物質とする電極を形成した。この厚さ及び質量から求めたこの電極の密度は０．５５であった。
[Experiment 2]
Poly (2,2,6,6-tetramethyl-4-phenyl) was prepared in the same manner as in Experimental Example 1, except that Lion Ketjen Black EC300J having a particle size of 39.5 μm was used instead of Denka Black in Experimental Example 1. An electrode active material slurry containing piperidinoxymethacrylate) was prepared. And it coats on 15-micrometer-thick Al foil using a coater, it is made to dry, 150-micrometer-thick poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) is made into an electrode active material An electrode was formed. The density of this electrode determined from this thickness and mass was 0.55.
次に、得られた電極を切り出し、実験例１と同様の方法で１００ＭＰａの圧力で電極プレスを行った。その結果、厚さ９６μｍ、全体の密度０．８６、電極集電体側の密度１．００の電極が得られた。 Next, the obtained electrode was cut out and subjected to electrode pressing at a pressure of 100 MPa in the same manner as in Experimental Example 1. As a result, an electrode having a thickness of 96 μm, an overall density of 0.86, and an electrode current collector side density of 1.00 was obtained.
次いで、実験例１と同様の方法で電極を打ち抜き、電解液を染み込ませて、有機ラジカル化合物であるポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）と粒子状の導電助剤ケッチェンブラックＥＣ３００Ｊとを含む電極活物質層を有する密閉型のコイン型二次電池を作製した。また、比較のために電極プレスをしていないものについてもコイン型二次電池を作製した
予備実験として、作製した二次電池のうち電極プレスをしていない電極を用いたセルを、０．１ｍＡの定電流で電圧４．２Ｖまで充電し、その後、０．１ｍＡの定電流で２．５Ｖまで放電した。その結果、このセルの放電容量は０．５５ｍＡｈであることがわかった。
Next, the electrode was punched out in the same manner as in Experimental Example 1, and the electrolyte solution was soaked into an organic radical compound, poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) and particulates. A sealed coin-type secondary battery having an electrode active material layer containing the conductive assistant Ketjen Black EC300J was prepared. For comparison, a coin-type secondary battery was also produced for those that were not subjected to electrode pressing. As a preliminary experiment, a cell using an electrode that was not subjected to electrode pressing among the produced secondary batteries was 0.1 mA. The battery was charged to a voltage of 4.2 V with a constant current of 0.1 mA and then discharged to 2.5 V with a constant current of 0.1 mA. As a result, it was found that the discharge capacity of this cell was 0.55 mAh.
この結果に基づいて、実験例１と同様の方法で作製したセルを６６ｍＡの定電流、すなわち１２０Ｃで充放電試験を行ったところ、容量は０．２８ｍＡｈとなった。一方、プレスしない電極を用いたセルの１２０Ｃでの放電容量は０．１８ｍＡｈに低下した。 Based on this result, when a cell produced by the same method as in Experimental Example 1 was subjected to a charge / discharge test at a constant current of 66 mA, that is, 120 C, the capacity was 0.28 mAh. On the other hand, the discharge capacity at 120 C of the cell using the electrode not pressed was reduced to 0.18 mAh.
また、交流インピーダンス測定で得られるＣｏｌｅ−Ｃｏｌｅプロットから見積もった電荷移動抵抗は６．４Ωとなり、電極プレスを行わないものの９．５Ωに比べて低インピーダンスであることがわかった。 In addition, the charge transfer resistance estimated from the Cole-Cole plot obtained by AC impedance measurement was 6.4Ω, and it was found that the impedance was lower than 9.5Ω although the electrode was not pressed.
このことから、電極活物質層における電極集電体側の密度が電解質側の密度に比べて大きい、プレス圧１００ＭＰａでプレスした電極は大電流でも容量低下が少なく、高出力用途に適したものであることがわかった。 From this, the density of the electrode current collector side in the electrode active material layer is larger than the density on the electrolyte side, and the electrode pressed at a press pressure of 100 MPa is less likely to decrease in capacity even at a large current and is suitable for high output applications. I understood it.
〔実験例３〕
実験例１のポリ（２，２，６，６−テトラメチル−４−ピペリジノキシメタクリレート）に代えてポリ（４−オキシ−２，２，６，６−テトラメチルピペリジノキシ）を使う以外は実験例１と同様の方法でポリ（４−オキシ−２，２，６，６−テトラメチルピペリジノキシ）を含む電極活物質スラリーを作製した。そして、コーターを用いて厚さ１５μｍのＡｌ箔上に塗工して乾燥させ、厚さ１５０μｍのポリ（４−オキシ−２，２，６，６−テトラメチルピペリジノキシ）を電極活物質とする電極を形成した。この厚さ及び質量から求めたこの電極の密度は０．６０であった。
[Experimental Example 3]
Instead of poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) in Experimental Example 1, poly (4-oxy-2,2,6,6-tetramethylpiperidinoxy) was used. An electrode active material slurry containing poly (4-oxy-2,2,6,6-tetramethylpiperidinoxy) was prepared in the same manner as in Experimental Example 1 except that it was used. And it coats on 15-micrometer-thick Al foil using a coater, it is made to dry, and 150-micrometer-thick poly (4-oxy-2,2,6,6-tetramethyl piperidinoxy) is made into an electrode active material An electrode was formed. The density of this electrode determined from this thickness and mass was 0.60.
次に、得られた電極を切り出し、実験例１と同様の方法で１００ＭＰａの圧力で電極プレスを行った。その結果、厚さ１００μｍ、全体の密度０．８４の電極が得られた。この電極の電極集電体側の密度は１．０２で、電極集電体側と反対側の密度は０．６５であった。 Next, the obtained electrode was cut out and subjected to electrode pressing at a pressure of 100 MPa in the same manner as in Experimental Example 1. As a result, an electrode having a thickness of 100 μm and an overall density of 0.84 was obtained. The density of this electrode on the electrode current collector side was 1.02, and the density on the side opposite to the electrode current collector side was 0.65.
次いで、実験例１と同様の方法で電極を打ち抜き、電解液を染み込ませて、有機ラジカル化合物であるポリ（４−オキシ−２，２，６，６−テトラメチルピペリジノキシ）と粒子状の導電助剤デンカブラックとを含む電極活物質層を有する密閉型のコイン型二次電池を作製した。また、比較のために電極プレスをしていないものについてもコイン型二次電池を作製した。 Next, the electrode was punched out in the same manner as in Experimental Example 1, and the electrolyte solution was soaked, and the organic radical compound poly (4-oxy-2,2,6,6-tetramethylpiperidinoxy) and particulates A sealed coin-type secondary battery having an electrode active material layer containing the conductive assistant Denka Black was prepared. For comparison, a coin-type secondary battery was also produced for a battery that was not subjected to electrode pressing.
予備実験として、作製した二次電池のうち電極プレスをしていない電極を用いたセルを、０．１ｍＡの定電流で電圧４．２Ｖまで充電し、その後、０．１ｍＡの定電流で２．５Ｖまで放電した。その結果、このセルの放電容量は０．５４ｍＡｈであることがわかった。 As a preliminary experiment, a cell using an electrode that was not subjected to electrode pressing among the produced secondary batteries was charged to a voltage of 4.2 V with a constant current of 0.1 mA, and then 2. with a constant current of 0.1 mA. Discharged to 5V. As a result, it was found that the discharge capacity of this cell was 0.54 mAh.
この結果に基づいて、実験例１と同様の方法で作製したセルを６４．８ｍＡの定電流、すなわち１２０Ｃで充放電試験を行ったところ、容量は０．３４ｍＡｈとなった。一方、プレスしない電極を用いたセルの６０Ｃでの放電容量は０．１７ｍＡｈに低下した。このことから、ポリ（４−オキシ−２，２，６，６−テトラメチルピペリジノキシ）を電極活物質とする場合にも、電極活物質層における電極集電体側の密度が電極集電体側と反対側の密度に比べて大きい電極は、大電流でも容量低下が少なく、高出力用途に適したものであることがわかった。 Based on this result, when the cell produced by the method similar to Experimental Example 1 was subjected to a charge / discharge test at a constant current of 64.8 mA, that is, 120 C, the capacity was 0.34 mAh. On the other hand, the discharge capacity at 60 C of the cell using the electrode not pressed was reduced to 0.17 mAh. Therefore, even when poly (4-oxy-2,2,6,6-tetramethylpiperidinoxy) is used as the electrode active material, the density on the electrode current collector side in the electrode active material layer is An electrode larger than the density on the opposite side of the body side was found to be suitable for high output applications with little reduction in capacity even at a large current.
１：電池缶
２：正極ケース
３：負極ケース
４：正極
５：セパレータ
６：負極
７：負極集電体
８：金属製ばね
９：電解質
１０：ガスケット
１５：電極集電体
１６：電極活物質層
１６ａ：電極集電体側と反対側（電解質側）
１６ｂ：電極集電体側
２０：二次電池用電極
５０：プレス
1: Battery can 2: Positive electrode case 3: Negative electrode case 4: Positive electrode 5: Separator 6: Negative electrode 7: Negative electrode current collector 8: Metal spring 9: Electrolyte 10: Gasket 15: Electrode current collector 16: Electrode active material layer 16a: The side opposite to the electrode current collector side (electrolyte side)
16b: Electrode current collector side 20: Secondary battery electrode 50: Press
Claims (5)
有機ラジカル化合物を含む電極活物質と粒子状の導電助剤とを含み、前記電極集電体の一方の主面上に形成された電極活物質層と、
を有する二次電池用電極であって、前記電極活物質層における電極集電体側の密度が前記電極集電体側と反対側の密度に比べて大きい二次電池用電極。 An electrode current collector;
An electrode active material layer containing an organic radical compound and a particulate conductive additive, and formed on one main surface of the electrode current collector,
The electrode for secondary batteries which has this, Comprising: The density for the electrode collector side in the said electrode active material layer is large compared with the density on the opposite side to the said electrode collector side.
有機ラジカル化合物を含む電極活物質と、粒子状の導電助剤と、を含む電極活物質スラリーを作製する工程と、
前記電極活物質スラリーを前記電極集電体の一方の主面に塗工して電極活物質層を形成する工程と、
前記電極活物質層を１２０℃以上の温度でプレスする工程と、
を備える二次電池用電極の製造方法。 Preparing an electrode current collector;
Producing an electrode active material slurry containing an electrode active material containing an organic radical compound and a particulate conductive additive;
Applying the electrode active material slurry to one main surface of the electrode current collector to form an electrode active material layer;
Pressing the electrode active material layer at a temperature of 120 ° C. or higher;
The manufacturing method of the electrode for secondary batteries provided with.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2009271888A JP2011029136A (en) | 2009-06-30 | 2009-11-30 | Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2009155485 | 2009-06-30 | ||
| JP2009271888A JP2011029136A (en) | 2009-06-30 | 2009-11-30 | Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2011029136A true JP2011029136A (en) | 2011-02-10 |
Family
ID=43637637
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2009271888A Pending JP2011029136A (en) | 2009-06-30 | 2009-11-30 | Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2011029136A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013065469A (en) * | 2011-09-16 | 2013-04-11 | Murata Mfg Co Ltd | Secondary battery system |
| US8592082B2 (en) | 2012-01-30 | 2013-11-26 | Samsung Sdi Co., Ltd. | Electrode assembly and secondary battery having the same |
| US20150340731A1 (en) * | 2014-05-21 | 2015-11-26 | Samsung Sdi Co., Ltd. | Electrode structure and lithium battery including the same |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004200058A (en) * | 2002-12-19 | 2004-07-15 | Nec Corp | Power storage device |
| JP2005050755A (en) * | 2003-07-31 | 2005-02-24 | Nissan Motor Co Ltd | Non-aqueous electrolyte battery |
| WO2006061948A1 (en) * | 2004-12-06 | 2006-06-15 | Nec Corporation | Process for producing polyradical compound and battery |
| WO2007125712A1 (en) * | 2006-04-27 | 2007-11-08 | Dupont Teijin Advanced Papers, Ltd. | Method for producing electrode sheet |
| JP2008282632A (en) * | 2007-05-09 | 2008-11-20 | Kyoto Univ | Secondary battery for energy regeneration |
-
2009
- 2009-11-30 JP JP2009271888A patent/JP2011029136A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004200058A (en) * | 2002-12-19 | 2004-07-15 | Nec Corp | Power storage device |
| JP2005050755A (en) * | 2003-07-31 | 2005-02-24 | Nissan Motor Co Ltd | Non-aqueous electrolyte battery |
| WO2006061948A1 (en) * | 2004-12-06 | 2006-06-15 | Nec Corporation | Process for producing polyradical compound and battery |
| WO2007125712A1 (en) * | 2006-04-27 | 2007-11-08 | Dupont Teijin Advanced Papers, Ltd. | Method for producing electrode sheet |
| JP2008282632A (en) * | 2007-05-09 | 2008-11-20 | Kyoto Univ | Secondary battery for energy regeneration |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013065469A (en) * | 2011-09-16 | 2013-04-11 | Murata Mfg Co Ltd | Secondary battery system |
| US8592082B2 (en) | 2012-01-30 | 2013-11-26 | Samsung Sdi Co., Ltd. | Electrode assembly and secondary battery having the same |
| US20150340731A1 (en) * | 2014-05-21 | 2015-11-26 | Samsung Sdi Co., Ltd. | Electrode structure and lithium battery including the same |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3678228B1 (en) | Negative electrode and secondary battery including the same | |
| US9843045B2 (en) | Negative electrode active material and method for producing the same | |
| JP5849701B2 (en) | Polymer radical material / activated carbon / conductive material composite for power storage device electrode, method for producing polymer radical material / activated carbon / conductive material composite for power storage device electrode, and power storage device | |
| Qian et al. | A free-standing Li4Ti5O12/graphene foam composite as anode material for Li-ion hybrid supercapacitor | |
| JP5684226B2 (en) | Fluorinated binder composites and carbon nanotubes for lithium battery positive electrodes | |
| KR101997074B1 (en) | Polyethyleneimine carbon-based material attached and separator for lithium-sulfur battery comprising the same | |
| US11551878B2 (en) | Electricity storage device | |
| EP3345232B1 (en) | Li-s battery with carbon coated separator | |
| KR101621519B1 (en) | Anode for lithium secondary battery, lithium secondary battery comprising the anode, and method of preparing the anode | |
| KR20130094366A (en) | Negative active material and lithium battery containing the material | |
| CN111095626B (en) | Negative active material for lithium secondary battery and method for preparing same | |
| JP4632020B2 (en) | Non-aqueous electrolyte secondary battery | |
| KR101924035B1 (en) | Silicon-carbon composite, preparation method thereof, and anode active material comprising the same | |
| JP2005209498A6 (en) | Non-aqueous electrolyte secondary battery | |
| KR20140099988A (en) | Anode active material for lithium secondary battery and lithium secondary battery comprising the same | |
| Yücel et al. | Powder-impregnated carbon fibers with lithium iron phosphate as positive electrodes in structural batteries | |
| JP2009135010A (en) | Nonaqueous electrolyte secondary battery | |
| KR102419750B1 (en) | Conductive polymer binder for novel silicon/graphene anodes in lithium-ion batteries | |
| JP5562688B2 (en) | Lithium ion capacitor manufacturing method and positive electrode manufacturing method | |
| CN107528065B (en) | Lithium secondary battery | |
| JP2011029136A (en) | Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery | |
| JP2011029135A (en) | Electrode for secondary battery, secondary battery, and manufacturing method of electrode for secondary battery | |
| JP2014072129A (en) | Electrode for power storage device and power storage device using the same | |
| CN115336040A (en) | Negative electrode and secondary battery comprising same | |
| KR20180107008A (en) | Negative electrode for lithium secondary battery, lithium secondary battery comprising the same, and preparing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20120925 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20131120 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20131203 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20140401 |