JP2016178051A - Lithium ion secondary battery - Google Patents

Lithium ion secondary battery Download PDF

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JP2016178051A
JP2016178051A JP2015058913A JP2015058913A JP2016178051A JP 2016178051 A JP2016178051 A JP 2016178051A JP 2015058913 A JP2015058913 A JP 2015058913A JP 2015058913 A JP2015058913 A JP 2015058913A JP 2016178051 A JP2016178051 A JP 2016178051A
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positive electrode
active material
battery
mixture layer
electrode active
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良幸 高森
Yoshiyuki Takamori
良幸 高森
千恵子 荒木
Chieko Araki
千恵子 荒木
野家　明彦
Akihiko Noie
明彦 野家
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Hitachi Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • 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

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which never reduces in capacity, nor worsens in current collector foil strength and degradation feature even in the case of using an electrode shaped in a thin film.SOLUTION: In a lithium ion secondary battery, a positive electrode mixture layer includes a positive electrode active material A expressed by LiNiCoMnO(x≥0.8, and x+y+z=1), and a positive electrode active material B expressed by LiNiCoMnO(x≤0.6, and x+y+z=1). The weight percentage of the positive electrode active material A to the total weight of the positive electrode active material A and the positive electrode active material B is in a range of 60-90 wt%. The average particle diameter (D50_A) of the positive electrode active material A is equal to or smaller than one half of the thickness of the positive electrode mixture layer on one side thereof. The cumulative 90%-particle size (D90_A) of the positive electrode active material A is equal to or smaller than the one-side thickness of the positive electrode mixture layer. The D50_A, and the average particle diameter (D50_B) of the active material B satisfy the following expression: D50_A>D50_B.SELECTED DRAWING: Figure 2

Description

本発明は、リチウムイオン二次電池に係わる。   The present invention relates to a lithium ion secondary battery.

リチウムイオン二次電池は、原子量が小さく、イオン化傾向が高いことから、他の二次電池と比較して体積エネルギー密度および重量エネルギー密度が高い。そのため、携帯電話やノートＰＣなどのポータブル機器用電源として広く使われている。さらに、地球温暖化防止や、化石燃料枯渇問題から、ハイブリッド自動車および電気自動車用電源、太陽光発電や風力発電などの再生可能エネルギーを利用した発電システムの電力貯蔵用電源などへの適用も進められている。
ここで、ハイブリッド自動車や電気自動車などの車載用のリチウムイオン二次電池については、燃費向上、走行距離の延長といった高容量化に加え、発進・加速時のエネルギー供給に対応するための高出力化が要求される。これら、リチウムイオン二次電池の課題のうち、高出力化については、その手法の一つとして合剤層を薄層化し、電極を大面積化することで低抵抗化する方法がある。しかし、一方で合剤層を薄層化した場合、集電箔やセパレーターといった直接電池反応に寄与しない部材の体積が増加し、電池の容器内に充填できる体積に占める合剤層の割合が低減してしまうため、電池容量が低減してしまうという問題が生じる。また、電極合剤層の薄層化を進めていくと、活物質粒子径の影響で、活物質充填率が高くできないという問題も生じることが明らかとなった。 Since the lithium ion secondary battery has a small atomic weight and a high ionization tendency, the volume energy density and the weight energy density are higher than those of other secondary batteries. Therefore, it is widely used as a power source for portable devices such as mobile phones and notebook PCs. Furthermore, because of global warming prevention and fossil fuel depletion problems, it is also being applied to power sources for hybrid and electric vehicles, power storage systems for power generation systems that use renewable energy such as solar power generation and wind power generation, etc. ing.
Here, for lithium-ion secondary batteries for in-vehicle use such as hybrid cars and electric cars, in addition to higher capacity such as improved fuel efficiency and longer mileage, higher output is required to support energy supply during start-up and acceleration. Is required. Among the problems of these lithium ion secondary batteries, one method for increasing the output is to reduce the resistance by thinning the mixture layer and increasing the area of the electrode. However, on the other hand, when the mixture layer is made thinner, the volume of members such as current collector foils and separators that do not directly contribute to the battery reaction increases, and the proportion of the mixture layer in the volume that can be filled in the battery container decreases. Therefore, there arises a problem that the battery capacity is reduced. Further, it has been clarified that when the electrode mixture layer is made thinner, there is a problem that the active material filling rate cannot be increased due to the effect of the active material particle diameter.

この問題を解決するため、特許文献１では、平均粒子径ａが４〜２０μｍである層状ニッケル・コバルト・マンガン複合酸化物（Ａ）と、平均粒子径ｂが４〜２０μｍである層状ニッケル・コバルト複合酸化物（Ｂ）で粒子径ａと粒子径ｂの比ｂ／ａが０．４〜２．５である活物質を混合する方法が提案されている。   In order to solve this problem, Patent Document 1 discloses a layered nickel / cobalt / manganese composite oxide (A) having an average particle diameter a of 4 to 20 μm and a layered nickel / cobalt having an average particle diameter b of 4 to 20 μm. A method of mixing an active material in which the ratio b / a of the particle diameter a to the particle diameter b is 0.4 to 2.5 in the composite oxide (B) has been proposed.

特開２０１４−５６６８３号JP 2014-56683 A

しかし、この方法においては、電極の薄層化の検討を進めていく中で、電極合剤層の厚さが３０μｍを下回ってくると、上述した活物質充填率が高くできないという問題を生じることが明らかとなった。例えば、合剤層の厚さαμｍの電極を作製しようとした場合、活物質粒子径がαμｍに近い値か大きいような場合、通常のプレス圧ではαμｍに圧縮できない、プレス圧を高くして無理にαμｍまで圧縮した場合には、活物質の二次粒子が壊れてしまい、一部の一次粒子が電池反応に寄与しない状態になる、あるいは集電箔内に活物質粒子がめり込み、集電箔が薄くなることで、集電箔の強度が低下してしまうなどの問題が生じることが明らかとなった。また、サイクル運転時や保存時の劣化に対して、改善の余地があることも分かった。   However, in this method, when the electrode layer thickness is less than 30 μm as the electrode thinning is proceeded, the above-mentioned active material filling rate cannot be increased. Became clear. For example, if an electrode with a mixture layer thickness of αμm is to be produced, if the active material particle diameter is close to or larger than αμm, it cannot be compressed to αμm with normal press pressure. When the material is compressed to α μm, the secondary particles of the active material are broken, and some primary particles do not contribute to the battery reaction, or the active material particles are sunk into the current collector foil. It has become clear that problems such as a decrease in strength of the current collector foil occur due to the decrease in thickness. It was also found that there was room for improvement with respect to deterioration during cycle operation and storage.

本発明の目的は、電極を薄膜化した場合でも、容量を下げることなく、また、集電箔の強度、劣化特性が低下しないリチウムイオン二次電池を提供することである。   An object of the present invention is to provide a lithium ion secondary battery in which the strength and deterioration characteristics of the current collector foil do not decrease even when the electrode is made thin.

本発明の特徴は、例えば、以下の通りである。 The features of the present invention are, for example, as follows.

正極と負極とを有するリチウムイオン二次電池において、前記正極は、電極と前記電極に塗布された正極合剤層を有し、前記正極合剤層は、ＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ≧０．８、ｘ＋ｙ＋ｚ＝１）で表わされる正極活物質ＡとＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ≦０．６、ｘ＋ｙ＋ｚ＝１）で表わされる正極活物質Ｂを有し、前記正極活物質Ａと前記正極活物質Ｂの総重量に対する前記正極活物質Ａの重量割合が６０〜９０ｗｔ％の範囲であり、前記正極活物質Ａの平均粒子径（Ｄ５０＿Ａ）が前記正極合剤層の片面厚さの１／２以下であり、前記正極活物質Ａの累積９０％粒径（Ｄ９０＿Ａ）が前記正極合剤層の片面厚さ以下であり、前記Ｄ５０＿Ａと前記活物質Ｂの平均粒子径（Ｄ５０＿Ｂ）がＤ５０＿Ａ＞Ｄ５０＿Ｂであるリチウムイオン二次電池。 In the lithium ion secondary battery having a positive electrode and a negative electrode, the positive electrode has an electrode and a positive electrode mixture layer applied to the electrode, and the positive electrode mixture layer is LiNi x Co y Mn z O 2 (x A positive electrode active material A represented by ≧ 0.8, x + y + z = 1) and a positive electrode active material B represented by LiNi x Co y Mn z O 2 (x ≦ 0.6, x + y + z = 1). The weight ratio of the positive electrode active material A to the total weight of the material A and the positive electrode active material B is in the range of 60 to 90 wt%, and the average particle diameter (D50_A) of the positive electrode active material A is one side of the positive electrode mixture layer It is 1/2 or less of the thickness, the cumulative 90% particle size (D90_A) of the positive electrode active material A is less than or equal to the thickness of one surface of the positive electrode mixture layer, and the average particle size of D50_A and the active material B ( D50_B) is D50_A> D50_B A lithium ion secondary battery.

本発明により、電極を薄膜化した場合でも、容量を下げることなく、また、集電箔の強度、劣化特性が低下しないリチウムイオン二次電池を提供することができる。   According to the present invention, it is possible to provide a lithium ion secondary battery in which the strength and deterioration characteristics of the current collector foil do not decrease even when the electrode is made thin.

リチウムイオン二次電池の概念図Conceptual diagram of lithium ion secondary battery 正極の概念図Conceptual diagram of positive electrode

以下、図面等を用いて、本発明の実施形態について説明する。以下の説明は本発明の内容の具体例を示すものであり、本発明がこれらの説明に限定されるものではなく、本明細書に開示される技術的思想の範囲内において当業者による様々な変更および修正が可能である。   Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible.

＜リチウムイオン二次電池＞
図１は、本発明の一実施形態に係る電池の内部構造を模式的に表す図である。図１に示す本発明の一実施形態に係る電池１は、正極１０、セパレータ１１、負極１２、電池容器（即ち電池缶）１３、正極集電タブ１４、負極集電タブ１５、内蓋１６、内圧開放弁１７、ガスケット１８、正温度係数（Ｐｏｓｉｔｉｖｅ ｔｅｍｐｅｒａｔｕｒｅ ｃｏｅｆｆｉｃｉｅｎｔ；ＰＴＣ）抵抗素子１９、及び電池蓋２０、軸心２１から構成される。電池蓋２０は、内蓋１６、内圧開放弁１７、ガスケット１８、及びＰＴＣ抵抗素子１９からなる一体化部品である。また、軸心２１には、正極１０、セパレータ１１及び負極１２が捲回されている。 <Lithium ion secondary battery>
FIG. 1 is a diagram schematically showing the internal structure of a battery according to an embodiment of the present invention. A battery 1 according to an embodiment of the present invention shown in FIG. 1 includes a positive electrode 10, a separator 11, a negative electrode 12, a battery container (that is, a battery can) 13, a positive electrode current collecting tab 14, a negative electrode current collecting tab 15, an inner lid 16, An internal pressure release valve 17, a gasket 18, a positive temperature coefficient (PTC) resistance element 19, a battery lid 20, and an axis 21 are included. The battery lid 20 is an integrated part composed of the inner lid 16, the internal pressure release valve 17, the gasket 18, and the PTC resistance element 19. A positive electrode 10, a separator 11, and a negative electrode 12 are wound around the shaft center 21.

セパレータ１１を正極１０及び負極１２の間に挿入し、軸心２１に捲回した電極群を作製する。軸心２１は、正極１０、セパレータ１１及び負極１２を担持できるものであれば、公知の任意のものを用いることができる。電極群は、図１に示した円筒形状の他に、短冊状電極を積層したもの、又は正極１０と負極１２を扁平状等の任意の形状に捲回したもの等、種々の形状にすることができる。電池容器１３の形状は、電極群の形状に合わせ、円筒形、偏平長円形状、扁平楕円形状、角形等の形状を選択してもよい。   The separator 11 is inserted between the positive electrode 10 and the negative electrode 12 to produce an electrode group wound around the axis 21. As the axis 21, any known one can be used as long as it can support the positive electrode 10, the separator 11, and the negative electrode 12. In addition to the cylindrical shape shown in FIG. 1, the electrode group has various shapes such as a laminate of strip electrodes, or a positive electrode 10 and a negative electrode 12 wound in an arbitrary shape such as a flat shape. Can do. The shape of the battery case 13 may be selected from shapes such as a cylindrical shape, a flat oval shape, a flat oval shape, and a square shape according to the shape of the electrode group.

電池容器１３の材質は、アルミニウム、ステンレス鋼、ニッケルメッキ鋼製等、非水電解質に対し耐食性のある材料から選択される。また、電池容器１３を正極１０又は負極１２に電気的に接続する場合は、非水電解質と接触している部分において、電池容器１３の腐食やリチウムイオンとの合金化による材料の変質が起こらないように、電池容器１３の材料の選定を行う。   The material of the battery case 13 is selected from materials that are corrosion-resistant to the nonaqueous electrolyte, such as aluminum, stainless steel, and nickel-plated steel. Further, when the battery container 13 is electrically connected to the positive electrode 10 or the negative electrode 12, the material is not deteriorated due to corrosion of the battery container 13 or alloying with lithium ions in the portion in contact with the nonaqueous electrolyte. Thus, the material of the battery container 13 is selected.

電池容器１３に電極群を収納し、電池容器１３の内壁に負極集電タブ１５を接続し、電池蓋２０の底面に正極集電タブ１４を接続する。電解液は、電池の密閉の前に電池容器内部１３に注入する。電解液の注入方法は、電池蓋２０を解放した状態にて電極群に直接添加する方法、又は電池蓋２０に設置した注入口から添加する方法がある。   The electrode group is housed in the battery container 13, the negative electrode current collecting tab 15 is connected to the inner wall of the battery container 13, and the positive electrode current collecting tab 14 is connected to the bottom surface of the battery lid 20. The electrolyte is injected into the battery container interior 13 before the battery is sealed. As a method for injecting the electrolyte, there are a method of adding directly to the electrode group in a state where the battery cover 20 is released, or a method of adding from an injection port installed in the battery cover 20.

その後、電池蓋２０を電池容器１３に密着させ、電池全体を密閉する。電解液の注入口がある場合は、それも密封する。電池を密閉する方法には、溶接、かしめ等公知の技術がある。   Thereafter, the battery lid 20 is brought into close contact with the battery container 13 to seal the entire battery. If there is an electrolyte inlet, seal it as well. As a method for sealing the battery, there are known techniques such as welding and caulking.

＜正極＞
図２は、本発明の正極１０を示す概略図である。 <Positive electrode>
FIG. 2 is a schematic view showing the positive electrode 10 of the present invention.

正極１０は、正極合剤層１０２と、正極集電体１０１とを備え、正極活物質及び結着材を含む正極合剤層１０２が、アルミニウム箔などの正極集電体１０１に塗布されることにより形成される。電子抵抗の低減のため更に正極合剤層に導電剤を加えても良い。   The positive electrode 10 includes a positive electrode mixture layer 102 and a positive electrode current collector 101, and the positive electrode mixture layer 102 including a positive electrode active material and a binder is applied to the positive electrode current collector 101 such as an aluminum foil. It is formed by. A conductive agent may be further added to the positive electrode mixture layer in order to reduce the electronic resistance.

正極合剤層１０２の厚さを薄くすることにより、電解液を介した活物質粒子表面へのＬｉイオンの供給がより容易となるため、高レートにおいても放電可能となり、電池１の出力を上げることができる。出力向上の観点から、正極合剤層１０２の厚さは片面の膜厚が６μｍ〜２５μｍであることが好ましく、特に６μｍ〜１５μｍが好ましい。電極の厚さをこの範囲内に設定することで、電池の容器に充填する電極の面積を大面積化し、電池の高出力化が実現できる。   By reducing the thickness of the positive electrode mixture layer 102, it becomes easier to supply Li ions to the surface of the active material particles via the electrolytic solution, so that discharge is possible even at a high rate, and the output of the battery 1 is increased. be able to. From the viewpoint of improving output, the thickness of the positive electrode mixture layer 102 is preferably 6 μm to 25 μm, particularly preferably 6 μm to 15 μm, on one side. By setting the thickness of the electrode within this range, the area of the electrode filled in the battery container can be increased, and high output of the battery can be realized.

しかし、上記のように合剤層を薄層化し、電池容器内に充填する電極面積を広くすることについて検討した結果、以下のような２つの大きな課題が生じる。   However, as a result of studying the thinning of the mixture layer and increasing the electrode area filled in the battery container as described above, the following two major problems arise.

ひとつめは、合剤層を薄くしていった場合、合剤層厚さと活物質粒径が近くなってくると、合剤層の密度が高くできないという課題である。もう一つの課題は、集電箔やセパレーターといった直接電池反応に寄与しない部材の体積が増加し、電池の容器内に充填できる体積に占める合剤層の割合が低減してしまうため、電池容量が低減してしまうという問題が生じる。   The first problem is that when the mixture layer is made thinner, the density of the mixture layer cannot be increased if the mixture layer thickness and the active material particle size become close to each other. Another problem is that the volume of members that do not directly contribute to the battery reaction, such as current collector foils and separators, increases, and the proportion of the mixture layer occupies the volume that can be filled in the battery container. The problem of being reduced arises.

これらの課題に対し発明者らは、車載用のリチウムイオン二次電池の課題である高出力化を実現するための正極について鋭意検討を重ねた結果、遷移金属組成の異なる２種類の正極活物質を、それぞれの粒子径を制御して混合することで、リチウムイオン二次電池の高出力化を実現するとともに、サイクル特性にも優れたリチウムイオン二次電池を開発することに成功した。   In response to these problems, the inventors have intensively studied the positive electrode for realizing high output, which is a problem of an in-vehicle lithium ion secondary battery, and as a result, two kinds of positive electrode active materials having different transition metal compositions. As a result, the lithium ion secondary battery has been successfully developed by improving the output of the lithium ion secondary battery and also having excellent cycle characteristics.

リチウムイオン二次電池用正極は、ＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ＋ｙ＋ｚ＝１）表わされる正極活物質を用いることができる。例えばｘ：ｙ：ｚ＝ １：１：１等のｘ、ｙ、ｚを同程度に含むものは、性能上バランスに優れる。しかし、上記のように、電極を薄くした場合は体積当たりの容量が下がる為、高容量の活物質を用いることが好ましく、上記ＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ＋ｙ＋ｚ＝１）で表わされる遷移金属元素のＮｉ、Ｃｏ、Ｍｎ組成が異なる２種の活物質を混合して用いることが好ましい。 A positive electrode active material represented by LiNi x Co y Mn z O 2 (x + y + z = 1) can be used for the positive electrode for a lithium ion secondary battery. For example, those containing x, y, and z, such as x: y: z = 1: 1: 1, have excellent balance in performance. However, as described above, when the electrode is thinned, the capacity per volume decreases. Therefore, it is preferable to use a high-capacity active material, and the transition represented by the above LiNi x Co y Mn z O 2 (x + y + z = 1). It is preferable to use a mixture of two active materials having different Ni, Co, and Mn compositions of metal elements.

２種の正極活物質のうちのひとつ（以下活物質Ａと記載する）は、ｘ≧０．８であることを特徴とする。もう一つの活物質（以下活物質Ｂと記載する）は、ｘ≦０．６であることを特徴とする。   One of the two types of positive electrode active materials (hereinafter referred to as active material A) is characterized in that x ≧ 0.8. Another active material (hereinafter referred to as active material B) is characterized in that x ≦ 0.6.

ここで、活物質Ａは遷移金属のうちのＮｉの含有量が高いことで、電池の高容量化が可能となる。単純に高容量化を進めるのであれば、活物質Ａのような理論的な容量が大きな活物質のみを用いるのが好ましい。ただし、活物質Ａのような高Ｎｉ材料は充電状態における熱安定性が低く、電池が何らかの不具合で過充電状態に陥った際、活物質から酸素が放出されやすく、熱暴走を起こす可能性が低Ｎｉ材料よりも高い。また、充放電の際Ｌｉイオンが挿入・脱離するためのサイトにＮｉが入り込んでしまうカチオンミキシングと呼ばれる現象が起こりやすく、サイクル特性が十分でないという問題がある。このような課題を解決するため、理論的な容量は若干少なくなるものの、熱安定性に優れ、かつカチオンミキシングが起こりにくくサイクル特性に優れたｘ≦０．６の活物質を混合することを特徴とする。これら２種の活物質を混合することで安全性やサイクル特性を大幅に向上することが可能となる。これらを考慮すると、活物質Ａと活物質Ｂの総重量に対する活物質Ａの重量割合は６０〜９０ｗｔ％の範囲であることが好ましい。   Here, since the active material A has a high content of Ni in the transition metal, the capacity of the battery can be increased. In order to simply increase the capacity, it is preferable to use only an active material having a large theoretical capacity such as the active material A. However, a high Ni material such as active material A has low thermal stability in the charged state, and when the battery falls into an overcharged state due to some trouble, oxygen is easily released from the active material, which may cause thermal runaway. Higher than low Ni material. In addition, there is a problem that a phenomenon called cation mixing, in which Ni enters a site for inserting and desorbing Li ions during charge and discharge, easily occurs, and cycle characteristics are not sufficient. In order to solve such a problem, the theoretical capacity is slightly reduced, but an active material of x ≦ 0.6 which is excellent in thermal stability and hardly causes cation mixing and has excellent cycle characteristics is mixed. And By mixing these two active materials, safety and cycle characteristics can be greatly improved. Considering these, the weight ratio of the active material A to the total weight of the active material A and the active material B is preferably in the range of 60 to 90 wt%.

正極活物質の粒径は、Ｎｉ含有量の多い活物質Ａの平均粒子径（Ｄ５０＿Ａ）が正極合剤層の片面厚さの１／２以下、かつ累積９０％粒子径（Ｄ９０＿Ａ）が正極合剤層の厚さ以下であり、活物質Ａの平均粒子径（Ｄ５０＿Ａ）と活物質Ｂの平均粒子径（Ｄ５０＿Ｂ）がＤ５０＿Ａ＞Ｄ５０＿Ｂの関係があることが重要である。なお、本発明においては平均粒子径は、粒子径分布の中央値に対応する粒子径であるメジアン径（ｄ５０）により表す。したがって、「累積５０％粒子径」と「平均粒子径」は同意味である。   The particle diameter of the positive electrode active material is such that the average particle diameter (D50_A) of the active material A having a high Ni content is ½ or less of the thickness of one surface of the positive electrode mixture layer, and the cumulative 90% particle diameter (D90_A) is the positive electrode composite. It is important that the average particle diameter (D50_A) of the active material A and the average particle diameter (D50_B) of the active material B have a relationship of D50_A> D50_B. In the present invention, the average particle diameter is represented by the median diameter (d50) which is the particle diameter corresponding to the median value of the particle diameter distribution. Therefore, “cumulative 50% particle size” and “average particle size” have the same meaning.

Ｎｉ含有量の高い活物質Ａは、活物質Ｂに比べ電解液の分解活性が高い、カチオンミキシングが起きやすいなどの問題があるため、活物質Ｂよりも平均粒子径が大きなものを用い比表面積を小さくすることで、これらの影響を抑制することが可能となる。さらに好ましくは、活物質Ａの平均粒子径（Ｄ５０＿Ａ）と活物質Ｂの平均粒子径（Ｄ５０＿Ｂ）の比Ｄ５０＿Ａ／Ｄ５０＿Ｂが１．４以上であることがより好ましい。平均粒子径をこのような比にすることにより、合剤層を薄くした場合にも充填率を高く保つことが可能となり、電池容量を下げることなく電池の高出力化が可能となる。   Since the active material A having a high Ni content has problems such as higher decomposition activity of the electrolytic solution than the active material B and cation mixing, the specific surface area is larger than that of the active material B. It is possible to suppress these influences by reducing. More preferably, the ratio D50_A / D50_B of the average particle diameter (D50_A) of the active material A to the average particle diameter (D50_B) of the active material B is more preferably 1.4 or more. By setting the average particle diameter to such a ratio, it is possible to keep the filling rate high even when the mixture layer is thinned, and it is possible to increase the output of the battery without reducing the battery capacity.

また、正極合剤層は、少なくとも前記正極活物質Ａと前記正極活物質Ｂを有するスラリーを前記電極に塗布し、６０ＭＰａ以下のプレス圧によりプレスしたことにより作製される。プレス圧をこの範囲にすることにより、粒子に必要以上の力がかかることを防ぐことができる。   The positive electrode mixture layer is produced by applying a slurry having at least the positive electrode active material A and the positive electrode active material B to the electrode and pressing it at a pressing pressure of 60 MPa or less. By setting the pressing pressure within this range, it is possible to prevent the particles from being applied with an excessive force.

以下、実施例にて本発明を具体的に説明する。   Hereinafter, the present invention will be specifically described with reference to examples.

＜正極の作製＞
まず、Ｄ５０が７μｍ、Ｄ９０が１５μｍである正極活物質Ａ（ＬｉＮｉ０．８Ｃｏ０．１Ｍｎ０．１Ｏ２）と、Ｄ５０が６μｍである正極活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）を、重量比Ａ：Ｂ＝６０：４０で混合した。この混合した正極活物質と炭素系導電材をそれぞれ８８重量部および７重量部の重量比で混合した。この混合物に結着剤であるＰＶＤＦを溶解したＮメチル−２ピロリドンを、ＰＶＤＦの重量が５重量部になるよう加え均一に混合し、正極合剤スラリーを作製した。 <Preparation of positive electrode>
First, a positive electrode active material A (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) having D50 of 7 μm and D90 of 15 μm, and a positive electrode active material B (LiNi 0.33 Co 0. 33 Mn 0.33 O 2 ) was mixed at a weight ratio A: B = 60: 40. The mixed positive electrode active material and carbon-based conductive material were mixed at a weight ratio of 88 parts by weight and 7 parts by weight, respectively. N-methyl-2-pyrrolidone in which PVDF as a binder was dissolved was added to this mixture so that the weight of PVDF was 5 parts by weight and mixed uniformly to prepare a positive electrode mixture slurry.

このスラリーを厚さ１５μｍのアルミ集電箔上に合剤層の塗工量が４０ｇ／ｍ２になるよう塗工した後、１２０℃で乾燥した。乾燥した電極は、直径１５ｍｍの円盤状に切り抜いたのち、ハンドプレス機を用いて電極密度が２．７ｇ／ｃｍ３になるように圧縮成型し、評価用の正極を作製した。なお、プレス圧は活物質の二次粒子が崩壊しないよう６０ＭＰａ以下で行った。活物質合剤の膜厚は１５μｍに調節した。 This slurry was coated on an aluminum current collector foil having a thickness of 15 μm so that the coating amount of the mixture layer was 40 g / m 2 , and then dried at 120 ° C. The dried electrode was cut out into a disk shape having a diameter of 15 mm, and then compression molded using a hand press so that the electrode density was 2.7 g / cm 3 , thereby producing a positive electrode for evaluation. The pressing pressure was 60 MPa or less so that the secondary particles of the active material did not collapse. The film thickness of the active material mixture was adjusted to 15 μm.

＜試作電池作製＞
前述した方法で作製した評価用正極と、長さ６ｃｍ、幅２ｃｍ、厚さ０．２ｃｍの金属リチウム板を負極として組み合わせ、試作用電池を作製した。電解液にはエチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）を体積比で１：２の割合で混合した溶媒に、ＬｉＰＦ６を１．０モル／Ｌの濃度となるよう添加したものを用いた。 <Production of prototype battery>
A prototype battery was fabricated by combining the positive electrode for evaluation produced by the method described above and a metal lithium plate having a length of 6 cm, a width of 2 cm, and a thickness of 0.2 cm as a negative electrode. The electrolyte used was a solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a volume ratio of 1: 2, and LiPF 6 was added to a concentration of 1.0 mol / L. .

＜試作した電極および電池の評価＞
まず、正極については、電極の厚さを測定し、電極密度が所定の密度（２．７ｇ／ｃｍ３）になっているかどうかを確認した。電池については、上限電圧４．３Ｖ、下限電圧３．０Ｖ、充放電レート０．２Ｃで充放電を３回繰り返して電池を初期化した。その後、０．５Ｃで上限電圧４．３Ｖまで充電した後、０．５Ｃで下限電圧３．０Ｖまで放電し、この際の放電容量を初期放電容量とした。さらに０．５Ｃで上限電圧３．９Ｖ、下限電圧３．３Ｖで５０サイクルの充放電を繰り返し、５０サイクル目の放電容量と初期放電容量との比から、容量維持率を算出した。 <Evaluation of prototype electrodes and batteries>
First, for the positive electrode, the thickness of the electrode was measured, and it was confirmed whether the electrode density was a predetermined density (2.7 g / cm 3 ). For the battery, the battery was initialized by repeating charge and discharge three times at an upper limit voltage of 4.3 V, a lower limit voltage of 3.0 V, and a charge / discharge rate of 0.2 C. Thereafter, the battery was charged at 0.5 C to an upper limit voltage of 4.3 V, and then discharged at 0.5 C to a lower limit voltage of 3.0 V. The discharge capacity at this time was defined as the initial discharge capacity. Furthermore, 50 cycles of charge and discharge were repeated at an upper limit voltage of 3.9 V and a lower limit voltage of 3.3 V at 0.5 C, and the capacity retention rate was calculated from the ratio between the discharge capacity at the 50th cycle and the initial discharge capacity.

活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が５μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) was 5 μm.

活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が４．５μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 A positive electrode for evaluation and a prototype battery are produced in the same manner as in Example 1 except that the average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) is 4.5 μm. did.

活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 A positive electrode for evaluation and a prototype battery are produced in the same manner as in Example 1 except that the average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) is 3.5 μm. did.

正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を５０：５０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was 50:50.

正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を７０：３０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was set to 70:30.

正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を８０：２０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was 80:20.

正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を９０：１０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was 90:10.

正極作製の際の、活物質Ｂの化学式がＬｉＮｉ０．６Ｃｏ０．２Ｍｎ０．２Ｏ２）であり、平均粒子径Ｄ５０が３．５μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 The chemical formula of the active material B at the time of producing the positive electrode is LiNi 0.6 Co 0.2 Mn 0.2 O 2 ) and the average particle diameter D50 is 3.5 μm. A positive electrode for evaluation and a prototype battery were prepared by the method.

[比較例１]
活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が７μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 1]
A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) was 7 μm.

[比較例２]
活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が７μｍであることおよび、電極のプレス圧が１００ＭＰａであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 2]
The same method as in Example 1 except that the average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) is 7 μm and the press pressure of the electrode is 100 MPa. Thus, a positive electrode for evaluation and a prototype battery were produced.

[比較例３]
正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を０：１００とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 3]
The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was set to 0: 100.

[比較例４]
正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を２０：８０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 4]
The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was 20:80.

[比較例５]
正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を４０：６０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 5]
The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was 40:60.

[比較例６]
正極作製の際の、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が３．５μｍであることおよび、活物質Ａと活物質Ｂの混合比率を１００：０とした以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 6]
The average particle diameter D50 of the active material B (LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) at the time of producing the positive electrode is 3.5 μm, and the mixing ratio of the active material A and the active material B is A positive electrode for evaluation and a prototype battery were produced in the same manner as in Example 1 except that the ratio was set to 100: 0.

[比較例７]
正極作製の際の、活物質Ａ（ＬｉＮｉ０．８Ｃｏ０．１Ｍｎ０．１Ｏ２）のＤ９０が２０μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。 [Comparative Example 7]
A positive electrode for evaluation and a prototype battery were prepared in the same manner as in Example 1 except that D90 of the active material A (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) at the time of producing the positive electrode was 20 μm. Produced.

[比較例８]
正極作製の際の、活物質Ａ（ＬｉＮｉ０．８Ｃｏ０．１Ｍｎ０．１Ｏ２）の平均粒径Ｄ５０が３．５μｍ、Ｄ９０が１０μｍ、活物質Ｂ（ＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２）の平均粒子径Ｄ５０が７μｍであること以外は、実施例１と同様の方法で評価用正極および試作電池を作製した。
表１に、本発明の実施例および比較例の評価用正極の作製条件をまとめて示す。 [Comparative Example 8]
The active material A (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) has an average particle diameter D50 of 3.5 μm, D90 of 10 μm, and an active material B (LiNi 0.33 Co 0. 33 Mn 0.33 O 2 ) A positive electrode for evaluation and a prototype battery were prepared in the same manner as in Example 1 except that the average particle diameter D50 was 7 μm.
Table 1 summarizes the conditions for producing the positive electrodes for evaluation of the examples of the present invention and the comparative examples.

Figure 2016178051
Figure 2016178051

（評価）
表２に本発明の実施例および比較例の評価結果をまとめたものを示す。まず、電極密度についてみると、比較例１の活物質Ａおよび活物質Ｂの平均粒子径の比が１：１の条件では、所定の電極密度よりも小さな値となっており、合剤層中の活物質の充填密度が低下してしまう結果が得られた。活物質Ａと活物質Ｂが同程度の粒径の場合、充填率が悪く、粒子間に隙間ができることによる。このため、活物質Ａの平均粒子径（Ｄ５０＿Ａ）と活物質Ｂの平均粒子径（Ｄ５０＿Ｂ）は、Ｄ５０＿Ａ＞Ｄ５０＿Ｂであることにより、粒子同士が効率良く充填される。実施例１は、この点で比較例１よりも充填率が改善されており、電極密度が高いが、活物質Ａと活物質Ｂの粒径が近いため、実施例２よりは電極密度が低くなっている。したがって、Ａの平均粒子径（Ｄ５０＿Ａ）とＢの平均粒子径（Ｄ５０＿Ｂ）の比（Ｄ５０＿Ａ／Ｄ５０＿Ｂ）は１．４以上であることが好ましい。 (Evaluation)
Table 2 summarizes the evaluation results of Examples and Comparative Examples of the present invention. First, regarding the electrode density, when the ratio of the average particle diameters of the active material A and the active material B in Comparative Example 1 is 1: 1, the value is smaller than the predetermined electrode density. As a result, the packing density of the active material was reduced. When the active material A and the active material B have the same particle size, the filling rate is poor and a gap is formed between the particles. For this reason, the average particle diameter (D50_A) of the active material A and the average particle diameter (D50_B) of the active material B are D50_A> D50_B, so that the particles are efficiently filled. In Example 1, the filling rate is improved as compared with Comparative Example 1 and the electrode density is high. However, since the particle sizes of the active material A and the active material B are close, the electrode density is lower than that of Example 2. It has become. Therefore, the ratio (D50_A / D50_B) of the average particle diameter of A (D50_A) to the average particle diameter of B (D50_B) is preferably 1.4 or more.

また、比較例９のようにＤ９０の値が２０μｍと、合剤の片層厚よりも大きい場合についても、電極密度が小さくなる結果となった。これは、合剤層の厚さを１５μｍにプレスする際に１５μｍ以上の粒子が存在すると、その粒子がプレスの妨げとなり、その粒子の周辺の密度が低くなってしまうことに起因する。   Moreover, also when the value of D90 was 20 micrometers and larger than the single-layer thickness of a mixture like the comparative example 9, it resulted in the electrode density becoming small. This is because when particles having a size of 15 μm or more are present when the thickness of the mixture layer is pressed to 15 μm, the particles obstruct the pressing, and the density around the particles becomes low.

初期放電容量に関しては、比較例３を基準として比較すると、本実施例の１〜９にあるように、活物質Ａの混合比率を５０％以上とすることで、初期放電容量を１０％以上向上できることが明らかとなった。   As for the initial discharge capacity, when compared with Comparative Example 3 as a reference, the initial discharge capacity is improved by 10% or more by setting the mixing ratio of the active material A to 50% or more as shown in 1 to 9 of this example. It became clear that we could do it.

比較例１と同じ組成で、電極作製の際のプレス圧を高くして電極密度を２．７ｇ／ｃｍ３まで上げた比較例２については、比較例１に対し初期放電容量が５％程度ではあるものの低下する結果となった。これは、プレスの際の高い圧力により、活物質の二次粒子の一部が崩壊し、これにより一次粒子の一部が孤立してしまったため、充放電に寄与しなくなった結果であると推定される。 In Comparative Example 2 having the same composition as Comparative Example 1 and increasing the press pressure during electrode production to increase the electrode density to 2.7 g / cm 3, the initial discharge capacity is about 5% compared to Comparative Example 1. Although it was, there was a decline result. This is presumed to be due to the fact that a part of the secondary particles of the active material collapsed due to the high pressure during pressing, and part of the primary particles were isolated by this, and thus no longer contributed to charge / discharge. Is done.

次に、表２の電極密度と初期放電容量の値から、合剤層の体積エネルギー密度を算出した。その結果、実施例１〜実施例９については比較例３を基準として比較すると、体積エネルギー密度が１０％以上向上できることが分かる。一方で、比較例１については、電極密度が低下した影響で、体積エネルギー密度が小さくなってしまった。   Next, the volume energy density of the mixture layer was calculated from the values of the electrode density and the initial discharge capacity in Table 2. As a result, when Example 1 to Example 9 are compared with reference to Comparative Example 3, it can be seen that the volume energy density can be improved by 10% or more. On the other hand, about the comparative example 1, the volume energy density became small under the influence that the electrode density fell.

容量維持率については、比較例４の９０％に対し、実施例１〜実施例９容量維持率は８２〜８８％と若干低下しているものの、いずれも１５０ｍＡｈ／ｇ以上の値を示しており、比較例４の１３５ｍＡｈ／ｇと比較すると１０％以上容量が多い結果となった。一方で、電極作製の際のプレス圧を高くした比較例２については、容量維持率が７８％と低い値となった。また、活物質Ａのみで構成した比較例６についても容量維持率は７７％と低い値となった。   About capacity maintenance rate, although Example 1-Example 9 capacity maintenance rate has fallen a little with 82-88% to 90% of comparative example 4, all have shown the value of 150 mAh / g or more. When compared with 135 mAh / g of Comparative Example 4, the capacity was 10% or more. On the other hand, about the comparative example 2 which made the press pressure high in the case of electrode preparation, the capacity | capacitance maintenance factor became a low value with 78%. In addition, the capacity retention rate of Comparative Example 6 including only the active material A was as low as 77%.

以上のように、リチウムイオン二次電池について、本実施形態で示したような活物質組成、平均粒子径とすることで、高容量化およびサイクル特性に優れるとともに、高出力化を達成することが可能となる。   As described above, with respect to the lithium ion secondary battery, by setting the active material composition and the average particle size as shown in the present embodiment, it is possible to achieve high capacity and cycle characteristics and to achieve high output. It becomes possible.

Figure 2016178051
Figure 2016178051

電池１、正極１０、セパレータ１１、負極１２、電池容器（電池缶）１３、正極集電タブ、１４、負極集電タブ１５、内蓋１６、内圧開放弁１７、ガスケット１８、正温度係数抵抗素子１９、電池蓋２０、軸心２１、集電体１０１、正極合剤層１０２、活物質Ａ１０３、活物質Ｂ１０４ Battery 1, positive electrode 10, separator 11, negative electrode 12, battery container (battery can) 13, positive electrode current collector tab 14, negative electrode current collector tab 15, inner lid 16, internal pressure release valve 17, gasket 18, positive temperature coefficient resistance element 19, battery cover 20, shaft 21, current collector 101, positive electrode mixture layer 102, active material A103, active material B104

Claims (4)

正極と負極とを有するリチウムイオン二次電池において、
前記正極は、電極と前記電極に塗布された正極合剤層を有し、
前記正極合剤層は、ＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ≧０．８、ｘ＋ｙ＋ｚ＝１）で表わされる正極活物質ＡとＬｉＮｉｘＣｏｙＭｎｚＯ２（ｘ≦０．６、ｘ＋ｙ＋ｚ＝１）で表わされる正極活物質Ｂを有し、
前記正極活物質Ａと前記正極活物質Ｂの総重量に対する前記正極活物質Ａの重量割合が６０〜９０ｗｔ％の範囲であり、
前記正極活物質Ａの平均粒子径（Ｄ５０＿Ａ）は、前記正極合剤層の片面厚さの１／２以下であり、
前記正極活物質Ａの累積９０％粒径（Ｄ９０＿Ａ）は、前記正極合剤層の片面厚さ以下であり、
前記Ｄ５０＿Ａと前記活物質Ｂの平均粒子径（Ｄ５０＿Ｂ）がＤ５０＿Ａ＞Ｄ５０＿Ｂであるリチウムイオン二次電池。 In a lithium ion secondary battery having a positive electrode and a negative electrode,
The positive electrode has an electrode and a positive electrode mixture layer applied to the electrode,
The positive electrode mixture layer is composed of a positive electrode active material A represented by LiNi x Co y Mn z O 2 (x ≧ 0.8, x + y + z = 1) and LiN x Co y Mn z O 2 (x ≦ 0.6, x + y + z). = 1) having a positive electrode active material B represented by
The weight ratio of the positive electrode active material A to the total weight of the positive electrode active material A and the positive electrode active material B is in the range of 60 to 90 wt%,
The average particle diameter (D50_A) of the positive electrode active material A is ½ or less of the single-sided thickness of the positive electrode mixture layer,
The cumulative 90% particle size (D90_A) of the positive electrode active material A is equal to or less than the thickness of one surface of the positive electrode mixture layer,
A lithium ion secondary battery in which an average particle diameter (D50_B) of the D50_A and the active material B is D50_A> D50_B. 請求項１において、
前記正極合剤層の膜厚は１０〜２５μｍの範囲であるリチウムイオン二次電池。 In claim 1,
The lithium ion secondary battery, wherein the thickness of the positive electrode mixture layer is in the range of 10 to 25 μm. 前記Ｄ５０＿Ａと前記Ｄ５０＿Ｂの比（Ｄ５０＿Ａ／Ｄ５０＿Ｂ）は、１．４以上であるリチウムイオン二次電池。   A ratio of D50_A to D50_B (D50_A / D50_B) is a lithium ion secondary battery having a ratio of 1.4 or more. 請求項３において、
前記正極合剤層は、少なくとも前記正極活物質Ａと前記正極活物質Ｂを有するスラリーを前記電極に塗布し、６０ＭＰａ以下のプレス圧によりプレスしたことにより作製されたリチウムイオン二次電池。 In claim 3,
The positive electrode mixture layer is a lithium ion secondary battery produced by applying a slurry having at least the positive electrode active material A and the positive electrode active material B to the electrode and pressing the electrode with a pressing pressure of 60 MPa or less.
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WO2018135253A1 (en) * 2017-01-20 2018-07-26 Ｎｅｃエナジーデバイス株式会社 Positive electrode active substance, positive electrode, and lithium ion secondary cell
US11909040B2 (en) 2018-11-29 2024-02-20 Lg Energy Solution, Ltd. Electrode assembly

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018135253A1 (en) * 2017-01-20 2018-07-26 Ｎｅｃエナジーデバイス株式会社 Positive electrode active substance, positive electrode, and lithium ion secondary cell
CN110235289A (en) * 2017-01-20 2019-09-13 远景Aesc能源元器件有限公司 Positive active material, anode and lithium ion secondary battery
JPWO2018135253A1 (en) * 2017-01-20 2019-11-07 株式会社エンビジョンＡｅｓｃエナジーデバイス Positive electrode active material, positive electrode and lithium ion secondary battery
US10998542B2 (en) 2017-01-20 2021-05-04 Envision Aesc Energy Devices Ltd. Positive electrode active material, positive electrode, and lithium ion secondary battery
CN110235289B (en) * 2017-01-20 2022-10-18 远景Aesc日本有限公司 Positive electrode active material, positive electrode, and lithium ion secondary battery
US11909040B2 (en) 2018-11-29 2024-02-20 Lg Energy Solution, Ltd. Electrode assembly

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