JP2014041699A

JP2014041699A - Positive electrode plate for nonaqueous secondary battery, and nonaqueous secondary battery using the same

Info

Publication number: JP2014041699A
Application number: JP2011031601A
Authority: JP
Inventors: Takuya Hirobe; 卓也廣部; Isao Fujiwara; 勲藤原; Toshibumi Nagino; 俊文名木野
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2011-02-17
Filing date: 2011-02-17
Publication date: 2014-03-06

Abstract

PROBLEM TO BE SOLVED: To provide a high-capacity battery with an increased percentage of an active material which is arranged so that the rise in resistance in a positive electrode plate can be suppressed by appropriately placing conductive materials in a positive electrode mixture layer even with the conductive materials are reduced.SOLUTION: A positive electrode plate 6 for a nonaqueous secondary battery comprises: a positive electrode current collector 1; and a positive electrode mixture layer 5 formed by coating the positive electrode current collector 1 with a positive electrode mixture coating material prepared by distributing, in a dispersant, positive electrode active materials 2, conductive materials 3, and a binding material 4 by mixing and kneading. The conductive materials 3 include: conductive materials in electrical contact with each other at connecting points of the positive electrode active materials 2 and the positive electrode current collector 1; and conductive materials 3 in electrical contact with each other at connecting points of the positive electrode active materials 2. The amount of the conductive materials 3 added is 0.1-1.3 pts.wt.

Description

本発明はリチウムイオン二次電池に代表される非水系二次電池に関し、特に非水系二次電池用正極板およびこれを用いた非水系二次電池に関するものである。 The present invention relates to a non-aqueous secondary battery represented by a lithium ion secondary battery, and more particularly to a positive electrode plate for a non-aqueous secondary battery and a non-aqueous secondary battery using the same.

近年、携帯用電子機器の電源として利用が広がっている非水系二次電池としてのリチウムイオン二次電池は、負極にリチウムの吸蔵および放出が可能な炭素質材料等を用い、正極にＬｉＣｏＯ２等の遷移金属とリチウムの複合酸化物を活物質として用いており、これによって、高電位で高放電容量のリチウムイオン二次電池を実現している。しかし、近年の電子機器および通信機器の多機能化に伴って更なるリチウムイオン二次電池の高容量化が望まれている。 In recent years, lithium ion secondary batteries as non-aqueous secondary batteries, which are widely used as power sources for portable electronic devices, use a carbonaceous material that can occlude and release lithium as a negative electrode, and LiCoO2 as a positive electrode. A composite oxide of transition metal and lithium is used as an active material, thereby realizing a lithium ion secondary battery having a high potential and a high discharge capacity. However, with the recent increase in functionality of electronic devices and communication devices, it is desired to further increase the capacity of lithium ion secondary batteries.

ここで、高容量のリチウムイオン二次電池を実現するための構成要素である電極板としては、正極板および負極板ともに各々の構成材料を塗料化した合剤塗料を集電体上に塗布し、乾燥後プレス等により規定の厚みまで圧縮する方法が用いられている。この際、活物質以外の構成材料である導電材および結着材の量を低減することで一層の高容量化が可能となる。 Here, as an electrode plate which is a component for realizing a high-capacity lithium ion secondary battery, a mixture paint obtained by coating each component material is applied to the current collector on both the positive electrode plate and the negative electrode plate. A method of compressing to a specified thickness by a press after drying is used. At this time, it is possible to further increase the capacity by reducing the amount of the conductive material and the binder which are constituent materials other than the active material.

しかし一般的には、導電材を低減すると正極合剤層の体積抵抗が上昇し電池容量が低下することが分かっている。 However, it is generally known that reducing the conductive material increases the volume resistance of the positive electrode mixture layer and decreases the battery capacity.

また、結着材を低減した場合には、正極合剤塗料の粘度が低下し沈降などの不具合を生じやすくなるとともに、正極合剤層と正極集電体間の密着力が不足して活物質の脱落などの不具合を生ずる。 In addition, when the binder is reduced, the viscosity of the positive electrode mixture paint is decreased, and problems such as sedimentation are liable to occur, and the adhesive force between the positive electrode mixture layer and the positive electrode current collector is insufficient. Cause problems such as falling off.

そこで、結着材の量を削減しても正極合剤塗料が適度な粘度を有し、また、正極合剤層と正極集電体が十分な密着力を得るために分子量の高いポリフッ化ビニリデンを用いることが提案されている（例えば、特許文献１、２参照）。 Therefore, even if the amount of the binder is reduced, the positive electrode mixture paint has an appropriate viscosity, and the positive electrode mixture layer and the positive electrode current collector have a high molecular weight to obtain sufficient adhesion. Has been proposed (see, for example, Patent Documents 1 and 2).

特開２００４−３５６００４号公報JP 2004-356004 A 特開２００６−１０７７５３号公報JP 2006-107753 A

しかしながら、高電位で高放電容量の電池を実現するためには、正極板の活物質比率を高くする必要があり、そのためには、導電材および結着材といった添加物を極限まで低減する必要がある。しかし、単純に導電材の量を低減すると正極集電体に塗布形成される正極合剤層の体積抵抗が上昇し電池容量が低下することがわかっている。また結着材の添加量を低減すると塗料の粘度が低下し沈降が生じやすくなり、正極合剤層と正極集電体間の密着力が不足して活物質の脱落などの不具合を生ずる。 However, in order to realize a battery with a high potential and a high discharge capacity, it is necessary to increase the active material ratio of the positive electrode plate. To that end, it is necessary to reduce additives such as a conductive material and a binder to the limit. is there. However, it has been found that when the amount of the conductive material is simply reduced, the volume resistance of the positive electrode mixture layer applied and formed on the positive electrode current collector increases and the battery capacity decreases. Further, when the amount of the binder added is reduced, the viscosity of the coating material is lowered and precipitation is likely to occur, and the adhesion between the positive electrode mixture layer and the positive electrode current collector is insufficient, resulting in problems such as dropping off of the active material.

上述した特許文献１および２の従来技術では結着材の溶解および分散については改善しているが、結着材削減による合剤層の脱落や導電材削減による体積抵抗の上昇に関しては考慮されていない。 In the prior arts of Patent Documents 1 and 2 described above, the dissolution and dispersion of the binder are improved, but the drop of the mixture layer due to the reduction of the binder and the increase in volume resistance due to the reduction of the conductive material are taken into consideration. Absent.

今回の発明は、正極合剤層に含まれる導電材を低減した場合でも、正極合剤層の体積抵抗の上昇を抑制し、高電位で高放電容量の電池を実現することを目的とする。 An object of the present invention is to realize a battery having a high potential and a high discharge capacity by suppressing an increase in volume resistance of the positive electrode mixture layer even when the conductive material contained in the positive electrode mixture layer is reduced.

上記目的を達成するために、本発明の非水系二次電池用正極板は、正極活物質と導電材および結着材を分散媒にて混練分散した正極合剤塗料を正極集電体の上に塗着させて正極合剤層を形成した非水系二次電池用正極板であって、前記正極活物質と正極集電体の接続点および正極活物質同士の接続点に導電材が配置され、前記接続点における隣接した導電材同士が導通接触し、かつ前記導電材が正極合剤層の中に正極活物質１００重量部に対して０．１〜１．３重量部の割合で含有したことを特徴とする。 In order to achieve the above object, the positive electrode plate for a non-aqueous secondary battery according to the present invention comprises a positive electrode mixture paint obtained by kneading and dispersing a positive electrode active material, a conductive material and a binder in a dispersion medium. A positive electrode plate for a non-aqueous secondary battery formed by applying a positive electrode mixture layer, wherein a conductive material is disposed at a connection point between the positive electrode active material and the positive electrode current collector and between the positive electrode active materials. The conductive materials adjacent to each other at the connection point are in conductive contact, and the conductive material is contained in the positive electrode mixture layer in a proportion of 0.1 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material. It is characterized by that.

本発明の非水系二次電池用正極板によると、少量の導電材で適度な導電作用を得ることが可能となり、かつ少量の結着材で適度な密着力を得ることが可能となり、正極合剤層における活物質の比率を高めた非水系二次電池用正極板を提供し、電池容量を高めることが可能となる。 According to the positive electrode plate for a non-aqueous secondary battery of the present invention, it is possible to obtain an appropriate conductive action with a small amount of a conductive material, and it is possible to obtain an appropriate adhesion with a small amount of a binder. A positive electrode plate for a non-aqueous secondary battery in which the ratio of the active material in the agent layer is increased can be provided, and the battery capacity can be increased.

本発明における一実施の形態の非水系二次電池の一例としての円筒形リチウムイオン二次電池の一部切欠斜視図1 is a partially cutaway perspective view of a cylindrical lithium ion secondary battery as an example of a non-aqueous secondary battery according to an embodiment of the present invention. 本発明における一実施の形態の非水系二次電池正極板の構成を示した断面模式図1 is a schematic cross-sectional view showing the configuration of a positive electrode plate for a nonaqueous secondary battery according to an embodiment of the present invention. 本発明における比較例の非水系二次電池正極板の構成を示した断面模式図Sectional schematic diagram showing the configuration of the positive electrode plate of the non-aqueous secondary battery of the comparative example in the present invention

本発明の第１の発明においては、正極活物質と導電材および結着材を分散媒にて混練分散した正極合剤塗料を正極集電体の上に塗着させて正極合剤層を形成した非水系二次電池用正極板であって、正極活物質と正極集電体の接続点および正極活物質同士の接続点に導電材が配置され、接続点における隣接した導電材同士が導通接触し、かつ導電材が正極合剤層の中に正極活物質１００重量部に対して０．１〜１．３重量部の割合で含有したことにより、少量の導電材により正極活物質および正極集電体との導通を確保することが可能であり、正極活物質の比率を高めて電池容量を高めることができる。 In the first aspect of the present invention, a positive electrode mixture layer is formed by applying a positive electrode mixture paint obtained by kneading and dispersing a positive electrode active material, a conductive material and a binder in a dispersion medium onto a positive electrode current collector. A positive electrode plate for a non-aqueous secondary battery, in which a conductive material is disposed at a connection point between the positive electrode active material and the positive electrode current collector and a connection point between the positive electrode active materials, and adjacent conductive materials at the connection point are in conductive contact with each other In addition, since the conductive material is contained in the positive electrode mixture layer at a ratio of 0.1 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material, the positive electrode active material and the positive electrode collector are collected by a small amount of the conductive material. It is possible to ensure electrical continuity with the electric body, and the battery capacity can be increased by increasing the ratio of the positive electrode active material.

本発明の第２の発明においては、正極合剤塗料として、導電材は分散媒に単独で分散した後に正極活物質および結着材と混練分散したものを用いたことにより、少量の導電材でも均等に正極活物質の表面に配置することが可能となり、導電性を確保することができる。 In the second invention of the present invention, as the positive electrode mixture paint, a conductive material is dispersed in a dispersion medium and then kneaded and dispersed with a positive electrode active material and a binder, so that even a small amount of conductive material can be used. It becomes possible to arrange | position uniformly on the surface of a positive electrode active material, and can ensure electroconductivity.

本発明の第３の発明においては、導電材として天然黒鉛、人造黒鉛、カーボンブラックおよび炭素繊維から選ばれた少なくとも１種類から選択することで、正極活物質同士または正極活物質と正極集電体の導電性を確保することが可能となる。 In the third invention of the present invention, the conductive material is selected from at least one selected from natural graphite, artificial graphite, carbon black and carbon fiber, so that the positive electrode active materials or the positive electrode active material and the positive electrode current collector are selected. It becomes possible to ensure the electrical conductivity of.

本発明の第４の発明においては、導電材の比表面積を５０〜１５０ｍ^２／ｇとすることで少量の添加量でも適度な導電性を確保し適正な体積抵抗が得られる。 In the fourth aspect of the present invention, by setting the specific surface area of the conductive material to 50 to 150 m ² / g, appropriate conductivity can be ensured even with a small addition amount, and an appropriate volume resistance can be obtained.

本発明の第５の発明においては、正極活物質がリチウム含有複合酸化物からなり、前記リチウム含有複合酸化物が、Ｃｏ、Ｍｇ、Ｍｎ、Ｎｉ、およびＡｌからなる群から選ばれた少なくとも１種類を含有することで、安全性に優れた高容量のリチウムイオン二次電池を得ることが可能となる。 In a fifth aspect of the present invention, the positive electrode active material is made of a lithium-containing composite oxide, and the lithium-containing composite oxide is at least one selected from the group consisting of Co, Mg, Mn, Ni, and Al. It becomes possible to obtain a high-capacity lithium ion secondary battery excellent in safety.

本発明の第６の発明においては、結着材が正極合剤層の中に正極活物質１００重量部に対して０．４〜１．３重量部の割合で含有することで、正極合剤層中の活物質比率を高め、高容量のリチウムイオン二次電池を得ることが可能となる。 In the sixth aspect of the present invention, the binder is contained in the positive electrode mixture layer in a proportion of 0.4 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material, so that the positive electrode mixture The active material ratio in the layer is increased, and a high-capacity lithium ion secondary battery can be obtained.

本発明の第７の発明においては、結着材の重量平均分子量を６０〜１５０万とすることで正極合剤塗料に適度な粘性を与え、かつ正極合剤層と正極集電体との間に適切な密着力を得ることができる。 In the seventh invention of the present invention, by setting the weight average molecular weight of the binder to 60 to 1,500,000, an appropriate viscosity is given to the positive electrode mixture paint, and between the positive electrode mixture layer and the positive electrode current collector. It is possible to obtain an appropriate adhesion force.

本発明の第８の発明においては、少なくともリチウム含有複合酸化物よりなる正極活物質と導電材および結着材を分散媒にて混練分散した正極合剤塗料を正極集電体の上に付着させて正極合剤層を形成した正極板と少なくともリチウムを保持しうる材料よりなる負極活物質と結着材を分散媒にて混練分散した負極合剤塗料を負極集電体の上に付着させて負極合剤層を形成した負極板との間に多孔質絶縁体を介在させ渦巻状に巻回または積層して構成した電極群を非水電解液とともに電池ケースに封入した非水系二次電池であって、正極板に上記第１〜７に記載の正極板を用いることで、容量の高い非水系二次電池を提供することができる。 In the eighth invention of the present invention, a positive electrode mixture paint prepared by kneading and dispersing at least a positive electrode active material comprising a lithium-containing composite oxide, a conductive material, and a binder with a dispersion medium is adhered onto the positive electrode current collector. A negative electrode mixture coating material in which a positive electrode plate having a positive electrode mixture layer formed thereon, a negative electrode active material made of a material capable of holding at least lithium and a binder is kneaded and dispersed in a dispersion medium is adhered onto the negative electrode current collector. A non-aqueous secondary battery in which a porous insulator is interposed between a negative electrode plate on which a negative electrode mixture layer is formed and a wound or laminated electrode group is enclosed in a battery case together with a non-aqueous electrolyte. And by using the positive electrode plate described in the above first to seventh for the positive electrode plate, a high capacity non-aqueous secondary battery can be provided.

以下、本発明の一実施の形態について円筒形のリチウムイオン二次電池を例として図面を参照しながら説明するが、本発明は、これのみに限定されることなく角形電池やコイン型電池、ラミネート型電池などでもかまわない。 Hereinafter, an embodiment of the present invention will be described by taking a cylindrical lithium ion secondary battery as an example with reference to the drawings. However, the present invention is not limited to this, and the present invention is not limited thereto. A type battery is also acceptable.

（実施の形態１）
図１は、本発明の一実施の形態にかかる非水系二次電池の構成について示す一部切欠斜視図である。 (Embodiment 1)
FIG. 1 is a partially cutaway perspective view showing the configuration of a nonaqueous secondary battery according to an embodiment of the present invention.

本発明の非水系二次電池としては例えば、図１に示したように複合リチウム酸化物を正極活物質とする正極板６とリチウムを保持しうる材料を負極活物質とする負極板７とを多孔質絶縁体としてのセパレータ８を介して渦巻状に巻回して電極群１１が構成されている。この電極群１１を有底円筒形の電池ケース１２の内部に絶縁板１３と共に収容し、電極群１１の下部より導出した負極リード９を電池ケース１２の底部に接続し、次いで電極群１１の上部より導出した正極リード１０を封口板１４に接続し、電池ケース１２に所定量の非水溶媒からなる非水電解液（図示せず）を注液した後、電池ケース１２の開口部に封口ガスケット１５を周縁に取り付けた封口板１４を挿入し電池ケース１２の開口部を内方向に折り曲げてかしめ封口して構成することができる。 As the nonaqueous secondary battery of the present invention, for example, as shown in FIG. 1, a positive electrode plate 6 using a composite lithium oxide as a positive electrode active material and a negative electrode plate 7 using a material capable of holding lithium as a negative electrode active material. An electrode group 11 is formed by spirally winding the separator 8 as a porous insulator. The electrode group 11 is accommodated in the bottomed cylindrical battery case 12 together with the insulating plate 13, the negative electrode lead 9 led out from the lower part of the electrode group 11 is connected to the bottom part of the battery case 12, and then the upper part of the electrode group 11 The positive electrode lead 10 led out is connected to the sealing plate 14, and a non-aqueous electrolyte solution (not shown) made of a non-aqueous solvent is poured into the battery case 12, and then a sealing gasket is formed in the opening of the battery case 12. A sealing plate 14 with 15 attached to the periphery can be inserted, and the opening of the battery case 12 can be bent inward and caulked and sealed.

以下に、本発明の一実施の形態にかかる非水系二次電池を構成する正極板６の構成について図２を参照しながら説明する。図２は、本発明の一実施の形態にかかる正極板６の正極集電体１近傍を示す要部拡大断面図である。 Below, the structure of the positive electrode plate 6 which comprises the non-aqueous secondary battery concerning one embodiment of this invention is demonstrated, referring FIG. FIG. 2 is an enlarged cross-sectional view of the main part showing the vicinity of the positive electrode current collector 1 of the positive electrode plate 6 according to the embodiment of the present invention.

まず、本発明の望ましい正極板６の構成としては、特に限定されないが正極集電体１として厚みが５μｍ〜３０μｍを有するアルミニウムやアルミニウム合金またはニッケルやニッケル合金製の金属箔を用いることができる。この正極集電体１の上に塗布する正極合剤塗料としては正極活物質２、導電材３、結着材４とを分散媒中に双腕式練合機等の分散機により混合分散させて正極合剤塗料が作製される。 First, the configuration of the desirable positive electrode plate 6 of the present invention is not particularly limited, but a metal foil made of aluminum, aluminum alloy, nickel or nickel alloy having a thickness of 5 μm to 30 μm can be used as the positive electrode current collector 1. As the positive electrode mixture paint applied on the positive electrode current collector 1, the positive electrode active material 2, the conductive material 3, and the binder 4 are mixed and dispersed in a dispersion medium by a disperser such as a double arm kneader. Thus, a positive electrode mixture paint is produced.

なお導電材３は、正極活物質２および結着材４と混合分散する前に、ビーズミルにて凝集を適切な粒径にまで分散し、再凝集を抑制するための分散剤としてポリビニルピロリドン、メチルセルロースなどを添加して適切な粒径を維持することで、正極活物質２と正極集電体１の接続点および正極活物質２同士の接続点に配置することが可能となる。 In addition, before conducting and mixing the positive electrode active material 2 and the binder 4, the conductive material 3 is dispersed to a suitable particle size by a bead mill, and polyvinylpyrrolidone, methylcellulose as a dispersant for suppressing reaggregation. It is possible to arrange at the connection point between the positive electrode active material 2 and the positive electrode current collector 1 and the connection point between the positive electrode active materials 2 by maintaining the appropriate particle size.

正極活物質２としては、リチウム含有複合酸化物からなり、前記リチウム含有複合酸化物が、Ｃｏ、Ｍｇ、Ｍｎ、Ｎｉ、およびＡｌからなる群から選ばれた少なくとも１種類を含有していることが望ましい。 The positive electrode active material 2 is made of a lithium-containing composite oxide, and the lithium-containing composite oxide contains at least one selected from the group consisting of Co, Mg, Mn, Ni, and Al. desirable.

導電材３としては、天然黒鉛、人造黒鉛、カーボンブラックおよび炭素繊維から選ばれた１種類を単独、あるいは複数種を組み合わせて用いても良い。 As the conductive material 3, one kind selected from natural graphite, artificial graphite, carbon black and carbon fiber may be used alone, or a plurality of kinds may be used in combination.

導電材３の添加量は正極活物質１００重量部に対して０．１〜１．３重量部であることが望ましい。導電材３の添加量が正極活物質１００重量部に対して０．１重量部未満の場合は正極合剤層５の体積抵抗が上昇することで放電特性が悪化して電池容量が低下し、また１．３重量部を超えると正極合剤層５に含まれる正極活物質の比率が減少し電池容量が低下するためである。 The addition amount of the conductive material 3 is desirably 0.1 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material. When the addition amount of the conductive material 3 is less than 0.1 parts by weight with respect to 100 parts by weight of the positive electrode active material, the volume resistance of the positive electrode mixture layer 5 is increased, so that the discharge characteristics are deteriorated and the battery capacity is reduced. On the other hand, when the amount exceeds 1.3 parts by weight, the ratio of the positive electrode active material contained in the positive electrode mixture layer 5 is decreased, and the battery capacity is decreased.

なお導電材３のＢＥＴ比表面積は５０〜３００ｍ^２／ｇであることが望ましい。導電材３のＢＥＴ比表面積が５０ｍ^２／ｇ未満の場合は、正極合剤層５の体積抵抗が上昇することで放電特性が悪化して電池容量が低下し、また３００ｍ^２／ｇを超えると導電材３のかさ密度が低下して正極合剤層５に含まれる正極活物質の比率が減少し電池容量が低下するためである。 The conductive material 3 preferably has a BET specific surface area of 50 to 300 m ² / g. When the BET specific surface area of the conductive material 3 is less than 50 m ² / g, when the volume resistance of the positive electrode mixture layer 5 is increased, the discharge characteristics are deteriorated and the battery capacity is reduced, and when it exceeds 300 m ² / g. This is because the bulk density of the conductive material 3 decreases, the ratio of the positive electrode active material contained in the positive electrode mixture layer 5 decreases, and the battery capacity decreases.

結着材４としては、分子量が６０〜１５０万のポリフッ化ビニリデン（ＰＶｄＦ）を用いることが望ましい。その理由は分子量が６０万未満だと正極合剤層５と正極集電体１の接着強度が十分に得られず、１５０万を超えると正極合剤塗料中でＰＶｄＦを溶解することが困難となり凝集が発生しやすくなるためである。 As the binder 4, it is desirable to use polyvinylidene fluoride (PVdF) having a molecular weight of 60 to 1,500,000. The reason is that if the molecular weight is less than 600,000, sufficient adhesion strength between the positive electrode mixture layer 5 and the positive electrode current collector 1 cannot be obtained, and if it exceeds 1.5 million, it is difficult to dissolve PVdF in the positive electrode mixture paint. This is because aggregation tends to occur.

なお結着材４の添加量は正極活物質１００重量部に対して０．４〜１．３重量部であることが望ましい。結着材４の添加量が正極活物質１００重量部に対して０．４重量部未満の場合は正極合剤層５と正極集電体１の接着強度が十分に得られず、また１．３重量部を超えると正極合剤層５に含まれる正極活物質の比率が低下し電池容量が低下するためである。 The amount of the binder 4 added is desirably 0.4 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material. When the added amount of the binder 4 is less than 0.4 parts by weight with respect to 100 parts by weight of the positive electrode active material, sufficient adhesion strength between the positive electrode mixture layer 5 and the positive electrode current collector 1 cannot be obtained. This is because when the amount exceeds 3 parts by weight, the ratio of the positive electrode active material contained in the positive electrode mixture layer 5 decreases, and the battery capacity decreases.

上記のようにして作製した正極合剤塗料はダイコーターなどを用いてアルミニウム箔からなる正極集電体１の上に塗布し、次いで乾燥した後にプレスにて所定の厚みまで圧縮することで正極合剤層５を形成した正極板６が得られる。 The positive electrode mixture paint prepared as described above is applied onto the positive electrode current collector 1 made of aluminum foil using a die coater, etc., then dried and then compressed to a predetermined thickness by a press. A positive electrode plate 6 on which the agent layer 5 is formed is obtained.

一方、負極板７については特に限定されないが、負極集電体として厚みが５μｍ〜２５μｍを有する銅または銅合金製の金属箔を用いることができる。この負極集電体の上に塗布する負極合剤塗料としては、負極活物質、結着材、必要に応じて導電材、増粘剤を分散媒中に双腕式練合機等の分散機により混合分散させて負極合剤塗料が作製される。 On the other hand, although it does not specifically limit about the negative electrode plate 7, The metal foil made from copper or a copper alloy which has thickness of 5 micrometers-25 micrometers can be used as a negative electrode collector. As the negative electrode mixture paint applied on the negative electrode current collector, a negative electrode active material, a binder, a conductive material as required, a thickener in a dispersion medium, a disperser such as a double arm kneader The negative electrode mixture paint is prepared by mixing and dispersing.

まず、負極活物質、結着材を適切な分散媒中に入れ、双腕式練合機等の分散機により混合分散して、負極集電体への塗布に最適な粘度に調整して混練を行うことで負極合剤塗料を作製することができる。 First, the negative electrode active material and the binder are placed in an appropriate dispersion medium, mixed and dispersed by a disperser such as a double arm kneader, and adjusted to the optimum viscosity for application to the negative electrode current collector. The negative electrode mixture paint can be prepared by performing the above.

負極活物質としては、各種天然黒鉛および人造黒鉛、シリサイドなどのシリコン系複合材料、および各種合金組成材料を用いることができる。 As the negative electrode active material, various natural graphites and artificial graphites, silicon-based composite materials such as silicide, and various alloy composition materials can be used.

このときの負極用結着材としてはＰＶｄＦおよびその変性体をはじめ各種結着材を用いることができるが、リチウムイオン受入れ性向上の観点から、スチレン−ブタジエン共重合体ゴム粒子（ＳＢＲ）およびその変性体にカルボキシメチルセルロース（ＣＭＣ）をはじめとするセルロース系樹脂等を併用することや少量添加するのがより好ましいといえる
。 Various binders including PVdF and modified products thereof can be used as the binder for the negative electrode at this time. From the viewpoint of improving lithium ion acceptability, styrene-butadiene copolymer rubber particles (SBR) and the binders thereof are used. It can be said that it is more preferable to use a cellulose resin such as carboxymethyl cellulose (CMC) in combination with the modified body or to add a small amount.

上記のように作製した負極合剤塗料を、ダイコーターなどを用いて銅箔からなる負極集電体の上に塗布し、次いで乾燥した後にプレスにて所定の厚みまで圧縮することで負極板７が得られる。 The negative electrode mixture paint prepared as described above is applied onto a negative electrode current collector made of copper foil using a die coater and the like, then dried, and then compressed to a predetermined thickness with a press to form the negative electrode plate 7 Is obtained.

非水電解液については、電解質塩としてＬｉＰＦ_６およびＬＩＢＦ_４などの各種リチウム化合物を用いることができる。また溶媒としてエチレンカーボネート（ＥＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、メチルエチルカーボネート（ＥＭＣ）、プロピレンカーボネイト（ＰＣ）を単独および組み合わせて用いることができる。また正負極上に良好な皮膜を形成させることや過充電時の安定性を保証するために、ビニレンカーボネート（ＶＣ）やシクロヘキシルベンゼン（ＣＨＢ）およびその変性体を用いることも好ましい。 For the non-aqueous electrolyte, various lithium compounds such as LiPF ₆ and LIBF ₄ can be used as the electrolyte salt. Further, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), and propylene carbonate (PC) can be used alone or in combination as a solvent. It is also preferable to use vinylene carbonate (VC), cyclohexylbenzene (CHB), and modified products thereof in order to form a good film on the positive and negative electrodes and to ensure stability during overcharge.

セパレータ８については、リチウムイオン二次電池の使用範囲に耐えうる組成であれば特に限定されないが、ポリエチレン、ポリプロピレンなどのオレフィン系樹脂の微多孔フィルムを、単一あるいは複合して用いるのが一般的でありまた態様として好ましい。このセパレータ８の厚みは特に限定されないが、１０〜２５μｍとすれば良い。 The separator 8 is not particularly limited as long as it has a composition that can withstand the range of use of the lithium ion secondary battery, but it is common to use a microporous film of an olefin-based resin such as polyethylene or polypropylene as a single or a composite. And preferred as an embodiment. Although the thickness of this separator 8 is not specifically limited, What is necessary is just to be 10-25 micrometers.

以下、具体的な実施例と比較例についてさらに詳しく説明する。
（実施例１）
本発明の一実施例について図面を参照しながら説明する。まず、導電材３として比表面積が１００ｍ^２／ｇのアセチレンブラックを適量のＮ−メチル−２−ピロリドンを分散媒としてビーズミルにて分散した後に分散剤としてのポリビニルピロリドンを添加して攪拌し、導電材ペーストを作製した。次に、正極活物質２として粒径が１０μｍのニッケル酸リチウムを１００重量部、アセチレンブラックを正極活物質２を１００重量部に対して０．６重量部となる量の導電材ペースト、結着材４として分子量が１００万のポリフッ化ビニリデンを正極活物質２を１００重量部に対して０．８重量部とを適量のＮ−メチル−２−ピロリドンと共に双腕式練合機にて攪拌し混練することで、正極合剤塗料を作製した。 Hereinafter, specific examples and comparative examples will be described in more detail.
Example 1
An embodiment of the present invention will be described with reference to the drawings. First, acetylene black having a specific surface area of 100 m ² / g as a conductive material 3 was dispersed in a bead mill using an appropriate amount of N-methyl-2-pyrrolidone as a dispersion medium, and then added with polyvinyl pyrrolidone as a dispersant and stirred. A material paste was prepared. Next, as the positive electrode active material 2, a conductive material paste in an amount of 0.6 parts by weight with respect to 100 parts by weight of lithium nickelate having a particle diameter of 10 μm and acetylene black to 100 parts by weight of the positive electrode active material, As material 4, polyvinylidene fluoride having a molecular weight of 1,000,000 was mixed with 0.8 part by weight of positive electrode active material 2 with 100 parts by weight of N-methyl-2-pyrrolidone in a double arm kneader. A positive electrode mixture paint was prepared by kneading.

次いで、上述の正極合剤塗料を厚みが１５μｍのアルミニウム箔よりなる正極集電体１に間欠的に塗布、乾燥を両面実施した後にプレスすることで片面側の合剤厚みが７０μｍの正極板６を作製した。その後、円筒形のリチウムイオン二次電池の規定されている幅にスリッタ加工して正極板６を作製した。 Next, the above positive electrode mixture paint is intermittently applied to the positive electrode current collector 1 made of an aluminum foil having a thickness of 15 μm, dried on both sides, and then pressed to form a positive electrode plate 6 having a mixture thickness of 70 μm on one side. Was made. Then, the positive electrode plate 6 was produced by slitting to the width | variety prescribed | regulated of the cylindrical lithium ion secondary battery.

さらに、この正極板６の正極集電体１が露出した部分に正極リード１０を接続し、この正極リード１０を被覆するように正極保護テープを貼り付けることで正極板６を構成した。 Further, a positive electrode lead 10 was connected to a portion of the positive electrode plate 6 where the positive electrode current collector 1 was exposed, and a positive electrode protective tape was applied so as to cover the positive electrode lead 10 to constitute the positive electrode plate 6.

一方、負極活物質として人造黒鉛を１００重量部、結着材としてスチレン−ブタジエン共重合体ゴム粒子分散体（固形分４０重量％）を負極活物質１００重量部に対して２．５重量部（結着材の固形分換算で１重量部）、増粘剤としてカルボキシメチルセルロースを負極活物質１００重量部に対して１重量部、および適量の水とともに双腕式練合機にて攪拌し、負極合剤塗料を作製した。 On the other hand, 100 parts by weight of artificial graphite as the negative electrode active material, and 2.5 parts by weight of styrene-butadiene copolymer rubber particle dispersion (solid content 40% by weight) as the binder with respect to 100 parts by weight of the negative electrode active material ( 1 part by weight in terms of solid content of the binder), 1 part by weight of carboxymethyl cellulose as a thickener with respect to 100 parts by weight of the negative electrode active material, and an appropriate amount of water, and agitation in a double arm kneader. A mixture paint was prepared.

次いで、上述の負極合剤塗料を厚みが１０μｍの銅箔よりなる負極集電体に間欠的に塗布し、乾燥を両面実施した後にプレスすることで片面側の合剤厚みが８０μｍの負極板７を作製した。その後、円筒形のリチウムイオン二次電池の規定されている幅にスリッタ加工して負極板７を作製した。 Next, the above negative electrode mixture paint is intermittently applied to a negative electrode current collector made of a copper foil having a thickness of 10 μm, dried on both sides, and then pressed to form a negative electrode plate 7 having a mixture thickness of 80 μm on one side. Was made. Thereafter, the negative electrode plate 7 was produced by slitting to a specified width of the cylindrical lithium ion secondary battery.

さらに、この負極板７の負極集電体が露出した部分に負極リード９を接続し、この負極リード９を被覆するように負極保護テープを貼り付けることで負極板７を構成した。 Further, a negative electrode lead 9 was connected to a portion of the negative electrode plate 7 where the negative electrode current collector was exposed, and a negative electrode protective tape was applied so as to cover the negative electrode lead 9 to constitute the negative electrode plate 7.

以上のようにして作製した正極板６と負極板７とを用いて、図１に示したように２０μｍ厚みのポリエチレン微多孔フィルムをセパレータ８とし巻回して渦巻状の電極群１１を構成した。この電極群１１を図１に示した有底円筒形の電池ケース１２の内部に絶縁板１３と共に収容し、電極群１１の下部より導出した負極リード９を電池ケース１２の底部に接続した。次いで、電極群１１の上部より導出した正極リード１０を封口板１４に接続し、電池ケース１２に所定量のＥＣ、ＤＭＣ、ＥＭＣ混合溶媒にＬｉＰＦ_６を１ＭとＶＣを３重量部溶解させた非水電解液（図示せず）を注液した。その後、電池ケース１２の開口部に封口ガスケット１５を周縁に取り付けた封口板１４を挿入し、電池ケース１２の開口部を内方向に折り曲げて、かしめ封口することにより作製した円筒形のリチウムイオン二次電池を実施例１とした。
（比較例１）
導電材３をビーズミルにて分散せずに正極活物質２および結着材４と共に双腕式練合機にて攪拌し混練した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 and the negative electrode plate 7 produced as described above, a polyethylene microporous film having a thickness of 20 μm was wound as a separator 8 as shown in FIG. The electrode group 11 was accommodated in the bottomed cylindrical battery case 12 shown in FIG. 1 together with the insulating plate 13, and the negative electrode lead 9 led out from the lower part of the electrode group 11 was connected to the bottom of the battery case 12. Next, the positive electrode lead 10 led out from the upper part of the electrode group 11 is connected to the sealing plate 14, and 1 part of LiPF ₆ and 3 parts by weight of VC are dissolved in a predetermined amount of EC, DMC, and EMC mixed solvent in the battery case 12. A water electrolyte (not shown) was injected. Thereafter, a sealing plate 14 having a sealing gasket 15 attached to the periphery thereof is inserted into the opening of the battery case 12, the opening of the battery case 12 is bent inward, and caulked and sealed. The secondary battery was designated as Example 1.
(Comparative Example 1)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the conductive material 3 was stirred and kneaded with the positive electrode active material 2 and the binder 4 together with the positive electrode active material 2 and the binder 4 without using a bead mill.

次いで、上述の正極合剤塗料を実施例１と同様に正極集電体１に塗布、乾燥し、スリッタ加工して正極板６を作製した。 Next, the positive electrode mixture paint described above was applied to the positive electrode current collector 1 in the same manner as in Example 1, dried, and slitted to produce a positive electrode plate 6.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例１とした。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 1.

実施例１と比較例１の結果を（表１）に示す。 The results of Example 1 and Comparative Example 1 are shown in (Table 1).

表１から明らかなように、導電材３をビーズミルで分散しない比較例１の場合は図３に示すように導電材３の凝集によって活物質密度が低下し電池容量が低下した。さらに導電材３の凝集により正極板６の体積抵抗が上昇することで正極活物質利用率も低下し電池容量がさらに低下した。 As is clear from Table 1, in the case of Comparative Example 1 in which the conductive material 3 was not dispersed by the bead mill, the active material density was reduced due to the aggregation of the conductive material 3 and the battery capacity was reduced as shown in FIG. Furthermore, the volume resistivity of the positive electrode plate 6 increased due to the aggregation of the conductive material 3, whereby the utilization rate of the positive electrode active material was decreased and the battery capacity was further decreased.

以上のように、導電材３をビーズミルで分散して導電材ペーストを作製し、導電材３の凝集を低減することが電池容量の増加に有効であることが確認された。 As described above, it was confirmed that reducing the aggregation of the conductive material 3 by dispersing the conductive material 3 with a bead mill to produce a conductive material paste is effective in increasing the battery capacity.

次に導電材３の添加量が適正範囲内で上下限の場合を実施例２、３に記し、適正範囲を超える場合を比較例２，３に記す。
（実施例２）
導電材として用いた比表面積が１００ｍ^２／ｇのアセチレンブラックの添加量を活物質
１００重量部に対して０．１重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Next, the case where the addition amount of the conductive material 3 is within the appropriate range is the upper and lower limits is described in Examples 2 and 3, and the case where it exceeds the appropriate range is described in Comparative Examples 2 and 3.
(Example 2)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of acetylene black having a specific surface area of 100 m ² / g used as the conductive material was changed to 0.1 parts by weight with respect to 100 parts by weight of the active material. .

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例２とした。
（実施例３）
導電材３として用いた比表面積が１００ｍ^２／ｇのアセチレンブラックの添加量を活物質１００重量部に対して１．３重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, a cylindrical lithium ion secondary battery was produced in the same manner as in Example 1, and Example 2 was obtained.
(Example 3)
A positive electrode mixture paint was prepared in the same manner as in Example 1, except that the amount of acetylene black having a specific surface area of 100 m ² / g used as the conductive material 3 was changed to 1.3 parts by weight with respect to 100 parts by weight of the active material. did.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例３とした。
（比較例２）
導電材３として用いた比表面積が１００ｍ^２／ｇのアセチレンブラックの添加量を活物質１００重量部に対して０．０５重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, a cylindrical lithium ion secondary battery was produced in the same manner as in Example 1, and Example 3 was obtained.
(Comparative Example 2)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of acetylene black having a specific surface area of 100 m ² / g used as the conductive material 3 was changed to 0.05 parts by weight with respect to 100 parts by weight of the active material. did.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例２とした。
（比較例３）
導電材３として用いた比表面積が１００ｍ^２／ｇのアセチレンブラックの添加量を活物質１００重量部に対して１．４重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 2.
(Comparative Example 3)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of acetylene black having a specific surface area of 100 m ² / g used as the conductive material 3 was changed to 1.4 parts by weight with respect to 100 parts by weight of the active material. did.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例３とした。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 3.

実施例２、３と比較例２，３の結果を（表２）に示す。 The results of Examples 2 and 3 and Comparative Examples 2 and 3 are shown in (Table 2).

表２から明らかなように、導電材３の添加量が適正値の０．１〜１．３重量部の下限から外れて０．０５重量部である比較例２の場合は導電材３が不足して正極板６の体積抵抗が上昇するために正極活物質利用率が低下し電池容量が低下する。また導電材３の添加量が適正値の０．１〜１．３重量部の上限から外れて１．４重量部である比較例３の場合は活物質密度が低く電池容量が低いことが分かる。 As is apparent from Table 2, in the case of Comparative Example 2 in which the amount of the conductive material 3 added is outside the lower limit of 0.1 to 1.3 parts by weight of the appropriate value, the conductive material 3 is insufficient. Then, since the volume resistance of the positive electrode plate 6 is increased, the utilization rate of the positive electrode active material is decreased and the battery capacity is decreased. Moreover, in the case of the comparative example 3 whose addition amount of the electrically conductive material 3 deviates from the upper limit of 0.1 to 1.3 parts by weight of an appropriate value, it can be seen that the active material density is low and the battery capacity is low. .

従って、導電材３の添加量は０．１〜１．３重量部が適正範囲であると考えられる。 Therefore, it is considered that 0.1 to 1.3 parts by weight of the conductive material 3 is in an appropriate range.

次に導電材３の比表面積が適正範囲内で上下限の場合を実施例４、５に記し、適正範囲を超える場合を比較例４，５に記す。
（実施例４）
導電材３を比表面積が５０ｍ^２／ｇのアセチレンブラックに変更した以外は実施例１と同様に正極合剤塗料を作製した。 Next, the cases where the specific surface area of the conductive material 3 is within the appropriate range and the upper and lower limits are described in Examples 4 and 5, and the cases where the specific surface area exceeds the appropriate range are described in Comparative Examples 4 and 5.
Example 4
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the conductive material 3 was changed to acetylene black having a specific surface area of 50 m ² / g.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例４とした。
（実施例５）
導電材３を比表面積が３００ｍ^２／ｇのアセチレンブラックに変更した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, a cylindrical lithium ion secondary battery was produced in the same manner as in Example 1, and Example 4 was obtained.
(Example 5)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the conductive material 3 was changed to acetylene black having a specific surface area of 300 m ² / g.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例５とした。
（比較例４）
導電材３を比表面積が４０ｍ^２／ｇのアセチレンブラックに変更した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, a cylindrical lithium ion secondary battery was produced in the same manner as in Example 1, and Example 5 was obtained.
(Comparative Example 4)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the conductive material 3 was changed to acetylene black having a specific surface area of 40 m ² / g.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例４とした。
（比較例５）
導電材３を比表面積が３２０ｍ^２／ｇのアセチレンブラックに変更した以外は実施例１と同様に正極合剤塗料を作製した。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 4.
(Comparative Example 5)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the conductive material 3 was changed to acetylene black having a specific surface area of 320 m ² / g.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例５とした。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, and used as Comparative Example 5.

実施例４、５と比較例４，５の結果を（表３）に示す。 The results of Examples 4 and 5 and Comparative Examples 4 and 5 are shown in (Table 3).

表３から明らかなように、導電材３の比表面積が適正値の５０〜３００ｍ^２／ｇの下限から外れて４０ｍ^２／ｇである比較例４の場合は正極合剤層５の導電性が不足して正極板６の体積抵抗が上昇するために正極活物質利用率が低下し電池容量が低下する。また導電材３の比表面積が適正値の上限から外れて３２０ｍ^２／ｇである比較例５の場合は導電材３のかさ密度が低下して正極合剤層５に含まれる正極活物質の比率が減少し電池容量が低下することが分かる。 Table 3 As is apparent, in the case of Comparative Example 4 The specific surface area of the conductive material 3 is disengaged from the lower limit of 50 to 300 m 2 / ^g of the proper value is 40 m 2 / ^g conductive electrode mixture layer 5 is Since the volume resistance of the positive electrode plate 6 increases and the positive electrode active material utilization rate decreases, the battery capacity decreases. Moreover, in the case of the comparative example 5 whose specific surface area of the electrically conductive material 3 deviates from the upper limit of an appropriate value and is 320 m < ² > / g, the bulk density of the electrically conductive material 3 falls and the ratio of the positive electrode active material contained in the positive mix layer 5 It can be seen that the battery capacity is reduced due to the decrease.

次に結着材の添加量が適正範囲内で上下限の場合を実施例６、７に記し、適正範囲を超える場合を比較例６、７に記す。
（実施例６）
結着材４として用いたポリフッ化ビニリデンの添加量を活物質１００重量部に対して０．４重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Next, the case where the addition amount of the binder is within the appropriate range and the upper and lower limits is described in Examples 6 and 7, and the case where the amount exceeds the appropriate range is described in Comparative Examples 6 and 7.
(Example 6)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of polyvinylidene fluoride used as the binder 4 was changed to 0.4 parts by weight with respect to 100 parts by weight of the active material.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例６とした。
（実施例７）
結着材４として用いたポリフッ化ビニリデンの添加量を活物質１００重量部に対して１．３重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, a cylindrical lithium ion secondary battery was produced in the same manner as in Example 1, and Example 6 was obtained.
(Example 7)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of polyvinylidene fluoride used as the binder 4 was changed to 1.3 parts by weight with respect to 100 parts by weight of the active material.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例７とした。
（比較例６）
結着材４として用いたポリフッ化ビニリデンの添加量を活物質１００重量部に対して０．３重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Using the positive electrode plate 6 manufactured as described above and the negative electrode plate 7 described in Example 1, a cylindrical lithium ion secondary battery was manufactured in the same manner as in Example 1, and Example 7 was obtained.
(Comparative Example 6)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of polyvinylidene fluoride used as the binder 4 was changed to 0.3 parts by weight with respect to 100 parts by weight of the active material.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例６とした。
（比較例７）
結着材４として用いたポリフッ化ビニリデンの添加量を活物質１００重量部に対して１．４重量部に変更した以外は実施例１と同様に正極合剤塗料を作製した。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 6.
(Comparative Example 7)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the amount of polyvinylidene fluoride used as the binder 4 was changed to 1.4 parts by weight with respect to 100 parts by weight of the active material.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例７とした。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 7.

実施例６、７と比較例６，７の結果を（表４）に示す。 The results of Examples 6 and 7 and Comparative Examples 6 and 7 are shown in (Table 4).

表４から明らかなように、結着材４の添加量が適正値の０．４〜１．３重量部の下限から外れて０．３重量部である比較例６の場合は正極集電体１と正極合剤層５との密着力が不足して正極合剤層が脱落し電池が作製できなかった。また結着材４の添加量が適正値の０．４〜１．３重量部の上限から外れて１．４重量部である比較例７の場合は活物質密度が低下し電池容量が低下した。 As is apparent from Table 4, in the case of Comparative Example 6 in which the added amount of the binder 4 deviates from the lower limit of 0.4 to 1.3 parts by weight of the appropriate value, the positive electrode current collector 1 and the positive electrode mixture layer 5 were insufficient, and the positive electrode mixture layer fell off, making it impossible to produce a battery. In addition, in the case of Comparative Example 7 in which the addition amount of the binder 4 is 1.4 parts by weight outside the upper limit of 0.4 to 1.3 parts by weight of an appropriate value, the active material density is reduced and the battery capacity is reduced. .

従って、結着材４の添加量は０．４〜１．３重量部が適正範囲であると考えられる。 Therefore, it is considered that 0.4 to 1.3 parts by weight of the addition amount of the binder 4 is in an appropriate range.

次に結着材４の分子量が適正範囲内で上下限の場合を実施例８，９に記し、適正範囲を
超える場合を比較例８、９に記す。
（実施例８）
結着材４として用いたポリフッ化ビニリデンの分子量を６０万に変更した以外は実施例１と同様に正極合剤塗料を作製した。 Next, the cases where the molecular weight of the binder 4 is within the appropriate range and the upper and lower limits are described in Examples 8 and 9, and the cases where the molecular weight exceeds the appropriate range are described in Comparative Examples 8 and 9.
(Example 8)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the molecular weight of polyvinylidene fluoride used as the binder 4 was changed to 600,000.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例８とした。
（実施例９）
結着材４として用いたポリフッ化ビニリデンの分子量を１５０万に変更した以外は実施例１と同様に正極合剤塗料を作製した。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1, and designated as Example 8.
Example 9
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the molecular weight of polyvinylidene fluoride used as the binder 4 was changed to 1,500,000.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し実施例９とした。
（比較例８）
結着材４として用いたポリフッ化ビニリデンの分子量を５０万に変更した以外は実施例１と同様に正極合剤塗料を作製した。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Example 9.
(Comparative Example 8)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the molecular weight of polyvinylidene fluoride used as the binder 4 was changed to 500,000.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例８とした。
（比較例９）
結着材４として用いたポリフッ化ビニリデンの分子量を１７０万に変更した以外は実施例１と同様に正極合剤塗料を作製した。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 8.
(Comparative Example 9)
A positive electrode mixture paint was prepared in the same manner as in Example 1 except that the molecular weight of polyvinylidene fluoride used as the binder 4 was changed to 1.7 million.

以上のようにして作製した正極板６と実施例１に記載の負極板７を用いて、実施例１と同様の方法で円筒形のリチウムイオン二次電池を作製し比較例９とした。 A cylindrical lithium ion secondary battery was produced in the same manner as in Example 1 by using the positive electrode plate 6 produced as described above and the negative electrode plate 7 described in Example 1 to obtain Comparative Example 9.

実施例８、９と比較例８，９の結果を（表５）に示す。 The results of Examples 8 and 9 and Comparative Examples 8 and 9 are shown in (Table 5).

表５から明らかなように、結着材４の分子量が適正値の６０〜１５０万の下限から外れて５０万である比較例８の場合は正極集電体１と正極合剤層５との密着力が不足して正極合剤層が脱落し電池が作製できなかった。また結着材４の分子量が適正値の６０〜１５０万の上限から外れて１７０万である比較例９の場合は結着材４の溶解が困難で凝集が多く存在し、活物質密度が低下して電池容量も低下した。 As is clear from Table 5, in the case of Comparative Example 8 in which the molecular weight of the binder 4 is 500,000, which is outside the lower limit of the appropriate value of 600 to 1,500,000, the positive electrode current collector 1 and the positive electrode mixture layer 5 Adhesive strength was insufficient, and the positive electrode mixture layer fell off, making it impossible to produce a battery. Further, in the case of Comparative Example 9 in which the molecular weight of the binder 4 deviates from the appropriate upper limit of 60 to 1,500,000 and is 1.7 million, the binder 4 is difficult to dissolve and there is much aggregation, and the active material density decreases. The battery capacity was also reduced.

従って、結着材４の分子量は６０〜１５０万が適正範囲であると考えられる。 Therefore, it is considered that the molecular weight of the binder 4 is in the appropriate range of 600 to 1,500,000.

なお実施例では導電材３をアセチレンブラックとしたが、これに限定されることはなく、天然黒鉛、人造黒鉛、カーボンブラックおよび炭素繊維でも問題ない。 In the embodiment, the conductive material 3 is acetylene black. However, the conductive material 3 is not limited to this, and there is no problem with natural graphite, artificial graphite, carbon black, and carbon fiber.

ここで、密着力の測定はＪＩＳ−Ｃ６４８１−１９９５に準拠した９０度剥離強度試験行った。正極集電体１への正極合剤層５の密着力は、正極合剤層５を両面テープで固定し、正極集電体１を正極合剤層５に対して垂直になる方向に引張り、毎分５０ｍｍの速さで連続的に約３０ｍｍ剥がして、この間での荷重の平均値を剥離強度として正極集電体１への正極合剤層５の密着力の評価に用いた。本検討の正極合剤層５の剥離強度が低いと、正極板６の加工（例えば、スリット、プレス）で正極合剤層５が脱落する危険性がある。 Here, the adhesion was measured by a 90-degree peel strength test based on JIS-C6481-1995. The adhesion force of the positive electrode mixture layer 5 to the positive electrode current collector 1 is obtained by fixing the positive electrode mixture layer 5 with a double-sided tape and pulling the positive electrode current collector 1 in a direction perpendicular to the positive electrode mixture layer 5. About 30 mm was peeled off continuously at a speed of 50 mm per minute, and the average value of the load during this period was used as the peel strength to evaluate the adhesion of the positive electrode mixture layer 5 to the positive electrode current collector 1. If the peel strength of the positive electrode mixture layer 5 in this study is low, there is a risk that the positive electrode mixture layer 5 may fall off during processing of the positive electrode plate 6 (for example, slitting or pressing).

また電池容量は、２５℃の環境下で０．３Ｃレートでの定電流充電後に４．２Ｖでの定電圧充電にて電流値が６０ｍＡになるまで充電した後、０．２Ｃレートの定電流で電圧が２．５Ｖに低下するまで放電した際の放電容量を測定した。 In addition, the battery capacity was charged at a constant current of 0.2 C after charging at a constant voltage of 4.2 V after constant current charging at a 0.3 C rate in an environment of 25 ° C. until the current value reached 60 mA. The discharge capacity at the time of discharging until the voltage dropped to 2.5V was measured.

また正極活物質利用率は、上記方法で測定した電池容量を電池に含まれる正極活物質２の重量で割って算出した。 The utilization rate of the positive electrode active material was calculated by dividing the battery capacity measured by the above method by the weight of the positive electrode active material 2 contained in the battery.

本発明にかかる非水系二次電池用負極板を用いた非水系二次電池は電池特性に優れたポータブル機器や電気自動車の電源として有用である。 The non-aqueous secondary battery using the negative electrode plate for a non-aqueous secondary battery according to the present invention is useful as a power source for portable devices and electric vehicles having excellent battery characteristics.

１正極集電体
２正極活物質
３導電材
４結着材
５正極合剤層
６正極板
７負極板
８セパレータ
９負極リード
１０正極リード
１１電極群
１２電池ケース
１３絶縁板
１４封口板
１５封口ガスケット DESCRIPTION OF SYMBOLS 1 Positive electrode collector 2 Positive electrode active material 3 Conductive material 4 Binder 5 Positive electrode mixture layer 6 Positive electrode plate 7 Negative electrode plate 8 Separator 9 Negative electrode lead 10 Positive electrode lead 11 Electrode group 12 Battery case 13 Insulating plate 14 Sealing plate 15 Sealing gasket

Claims

正極活物質と導電材および結着材を分散媒にて混練分散した正極合剤塗料を正極集電体の上に塗着させて正極合剤層を形成した非水系二次電池用正極板であって、前記正極活物質と正極集電体の接続点および正極活物質同士の接続点に導電材が配置され、前記接続点における隣接した導電材同士が導通接触し、かつ前記導電材が正極合剤層の中に正極活物質１００重量部に対して０．１〜１．３重量部の割合で含有したことを特徴とする非水系二次電池用正極板。 A positive electrode plate for a non-aqueous secondary battery having a positive electrode mixture layer formed by coating a positive electrode mixture coating material obtained by kneading and dispersing a positive electrode active material, a conductive material and a binder with a dispersion medium on a positive electrode current collector. A conductive material is disposed at a connection point between the positive electrode active material and the positive electrode current collector and a connection point between the positive electrode active materials, the conductive materials adjacent to each other at the connection point are in conductive contact, and the conductive material is a positive electrode. A positive electrode plate for a non-aqueous secondary battery, which is contained in the mixture layer at a ratio of 0.1 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material.

前記正極合剤塗料として、前記導電材は分散媒に単独で分散した後に正極活物質および結着材と混練分散したものを用いたことを特徴とする請求項１に記載の非水系二次電池用正極板。 2. The non-aqueous secondary battery according to claim 1, wherein as the positive electrode mixture paint, the conductive material is dispersed in a dispersion medium and then kneaded and dispersed with a positive electrode active material and a binder. Positive electrode plate.

前記導電材として天然黒鉛、人造黒鉛、カーボンブラックおよび炭素繊維から選ばれた少なくとも１種類からなる請求項１に記載の非水系二次電池用正極板。 2. The positive electrode plate for a non-aqueous secondary battery according to claim 1, comprising at least one selected from natural graphite, artificial graphite, carbon black, and carbon fiber as the conductive material.

前記導電材のＢＥＴ比表面積を５０〜３００ｍ^２／ｇとすることを特徴とする請求項１に記載の非水系二次電池用正極板。 The positive electrode plate for a non-aqueous secondary battery according to claim 1, wherein the conductive material has a BET specific surface area of 50 to 300 m ² / g.

前記正極活物質がリチウム含有複合酸化物からなり、前記リチウム含有複合酸化物が、Ｃｏ、Ｍｇ、Ｍｎ、Ｎｉ、およびＡｌからなる群から選ばれた少なくとも１種類を含有する請求項１に記載の非水系二次電池用正極板。 The positive electrode active material is made of a lithium-containing composite oxide, and the lithium-containing composite oxide contains at least one selected from the group consisting of Co, Mg, Mn, Ni, and Al. A positive electrode plate for a non-aqueous secondary battery.

前記結着材が正極合剤層の中に正極活物質１００重量部に対して０．４〜１．３重量部の割合で含有したことを特徴とする非水系二次電池用正極板。 The positive electrode plate for a non-aqueous secondary battery, wherein the binder is contained in the positive electrode mixture layer in a proportion of 0.4 to 1.3 parts by weight with respect to 100 parts by weight of the positive electrode active material.

前記正極合材塗料は結着材として重量平均分子量が６０〜１５０万のポリフッ化ビニリデンもしくはポリフッ化ビニリデンとポリテトラフロオロエチレンとの共重合体を用いたことを特徴とする請求項１に記載の非水系二次電池用正極板。 2. The positive electrode composite coating material according to claim 1, wherein a polyvinylidene fluoride having a weight average molecular weight of 60 to 1,500,000 or a copolymer of polyvinylidene fluoride and polytetrafluoroethylene is used as a binder. The positive electrode plate for non-aqueous secondary batteries.

少なくともリチウム含有複合酸化物よりなる正極活物質と導電材および結着材を分散媒にて混練分散した正極合剤塗料を正極集電体の上に付着させて正極合剤層を形成した正極板と少なくともリチウムを保持しうる材料よりなる負極活物質と結着材を分散媒にて混練分散した負極合剤塗料を負極集電体の上に付着させて負極合剤層を形成した負極板との間に多孔質絶縁体を介在させ渦巻状に巻回または積層して構成した電極群を非水電解液とともに電池ケースに封入した非水系二次電池であって、前記正極板に請求項１〜７のいずれか一つに記載の非水系二次電池用正極板を用いたことを特徴とする非水系二次電池。 A positive electrode plate having a positive electrode mixture layer formed by adhering a positive electrode mixture coating material obtained by kneading and dispersing a positive electrode active material comprising at least a lithium-containing composite oxide, a conductive material, and a binder in a dispersion medium onto a positive electrode current collector And a negative electrode plate in which a negative electrode mixture layer is formed by adhering a negative electrode mixture coating material obtained by kneading and dispersing a negative electrode active material made of a material capable of holding lithium and a binder in a dispersion medium onto a negative electrode current collector; A non-aqueous secondary battery in which an electrode group formed by winding or laminating a porous insulator with a non-aqueous electrolyte solution enclosed in a battery case with a porous insulator interposed therebetween is provided on the positive electrode plate. A nonaqueous secondary battery using the positive electrode plate for a nonaqueous secondary battery according to any one of 7 to 7.