JP2014211944A - Electrode plate for nonaqueous secondary battery and nonaqueous secondary battery using the same - Google Patents
Electrode plate for nonaqueous secondary battery and nonaqueous secondary battery using the same Download PDFInfo
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- JP2014211944A JP2014211944A JP2011185503A JP2011185503A JP2014211944A JP 2014211944 A JP2014211944 A JP 2014211944A JP 2011185503 A JP2011185503 A JP 2011185503A JP 2011185503 A JP2011185503 A JP 2011185503A JP 2014211944 A JP2014211944 A JP 2014211944A
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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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
Description
本発明は、リチウムイオン電池に代表される非水系二次電池用電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 an electrode plate for a non-aqueous secondary battery represented by a lithium ion battery and a non-aqueous secondary battery using the same.
近年、電気自動車用の電源として利用が広がりつつあるリチウムイオン二次電池は、負極板にリチウムの吸蔵・放出が可能な炭素質材料等を用い、正極板にＬｉＣｏＯ2等の遷移金属とリチウム含有複合酸化物を正極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二次電池を実現しているが、近年の電気自動車用電源の需要増加に伴ってさらなる高容量化、長寿命化、高安全性が望まれている。 In recent years, lithium ion secondary batteries, which are increasingly used as power sources for electric vehicles, use a carbonaceous material capable of occluding and releasing lithium in the negative electrode plate, and contain a transition metal such as LiCoO 2 and lithium in the positive electrode plate The composite oxide is used as the positive electrode active material, and as a result, a secondary battery with a high potential and a high discharge capacity is realized. Life expectancy and high safety are desired.
ここで、高容量化、長寿命化、高安全性電池を実現するための電極板としては、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電極合剤塗料を集電体の上に塗布する方法が用いられており、さらには合剤層を複数層塗布する方法も提案されている。 Here, as an electrode plate for realizing a high capacity, long life, and high safety battery, an electrode mixture paint made by coating each constituent material on both the positive electrode plate and the negative electrode plate is placed on the current collector. The method of apply | coating is used, Furthermore, the method of apply | coating multiple layers of mixture layers is also proposed.
この際、複数層塗布する表面層の材料特性によって、一層の長寿命化、高安全性が可能となる。 At this time, a longer life and higher safety can be achieved depending on the material properties of the surface layer to be applied.
一方で、上記のように集電体に合剤層を塗布する際に、合剤層の端部がペーストの表面張力により盛上りが形成されるため、盛り上がり端部の位置を規定することで、内部短絡を防止する方法が提案されている。（例えば、特許文献１参照）。 On the other hand, when the mixture layer is applied to the current collector as described above, the end portion of the mixture layer is swelled by the surface tension of the paste. A method for preventing an internal short circuit has been proposed. (For example, refer to Patent Document 1).
しかしながら、上述した特許文献１に示される従来技術では、正極板と負極板との距離は、合剤層端部が盛上っている分だけ、合剤層の端部に対応する部分において近くなる。その結果、合剤層の端部に電荷が集中しリチウムが析出することでサイクル特性低下の課題が発生するものとなっていた。 However, in the prior art disclosed in Patent Document 1 described above, the distance between the positive electrode plate and the negative electrode plate is close to the portion corresponding to the end portion of the mixture layer, as much as the end portion of the mixture layer is raised. Become. As a result, charge concentrates on the end portion of the mixture layer and lithium is deposited, which causes a problem of deterioration in cycle characteristics.
本発明は前記従来の課題を解決するもので、合剤層の端部の厚みを合剤層の端部以外の厚みよりも薄くするとともに、合剤層の端部表面をリチウムの反応性が高くリチウム析出を抑制する表面層で覆うことで、リチウム受入性を向上させ、合剤層端部の電荷集中を防ぐことができ、合剤層端部でのリチウム析出を抑制する非水系二次電池用電極板および非水系二次電池を提供することを目的としている。 The present invention solves the above-mentioned conventional problems, and the thickness of the end portion of the mixture layer is made thinner than the thickness of the mixture layer other than the end portion, and the surface of the end portion of the mixture layer has lithium reactivity. Non-aqueous secondary that suppresses lithium deposition at the end of the mixture layer by improving the lithium acceptability and preventing charge concentration at the end of the mixture layer by covering it with a surface layer that highly suppresses lithium precipitation An object of the present invention is to provide a battery electrode plate and a non-aqueous secondary battery.
上記目的を達成するために本発明の非水系二次電池用電極板およびこれを用いた非水系二次電池は、合剤層の端部の厚みを合剤層の端部以外の厚みよりも薄くするとともに、合剤層の端部表面をリチウムの反応性が高くリチウム析出を抑制する表面層で覆ったことを特徴とする。 In order to achieve the above object, the electrode plate for a non-aqueous secondary battery and the non-aqueous secondary battery using the same according to the present invention have a thickness of the end portion of the mixture layer smaller than a thickness other than the end portion of the mixture layer. The surface of the mixture layer is covered with a surface layer that is highly reactive to lithium and suppresses lithium deposition.
本発明によれば、合剤層の端部でのリチウム析出を抑制し、充放電サイクル特性に優れ
た非水系二次電池を得ることができる。
ADVANTAGE OF THE INVENTION According to this invention, the lithium precipitation in the edge part of a mixture layer can be suppressed, and the non-aqueous secondary battery excellent in the charge / discharge cycle characteristic can be obtained.
本発明の第１の発明は、合剤層の端部の厚みを合剤層の端部以外の厚みよりも薄くするとともに、合剤層の端部表面をリチウムの反応性が高くリチウム析出を抑制する表面層で覆うことにより、合剤層の端部のリチウム反応性を平滑化させ、合剤層の端部での電荷集中を防ぐことでリチウム析出を抑制でき、サイクル特性を向上させることができる。 According to the first aspect of the present invention, the thickness of the end portion of the mixture layer is made thinner than the thickness other than the end portion of the mixture layer, and the surface of the end portion of the mixture layer is lithium-reactive and lithium is deposited. By covering with a suppressing surface layer, the lithium reactivity at the end of the mixture layer can be smoothed, and lithium precipitation can be suppressed by preventing charge concentration at the end of the mixture layer, thereby improving cycle characteristics. Can do.
本発明の第２の発明は、前記合剤層の端部の厚みは、前記合剤層の端部に向かうにつれて薄くすることで、合剤層の端部表面を表面層で覆うことにより、合剤層の端部のリチウム反応性を平滑化させ、合剤層の端部での電荷集中を防ぐことでリチウム析出を抑制でき、サイクル特性を向上させることができる。 According to a second aspect of the present invention, the thickness of the end portion of the mixture layer is reduced as it goes toward the end portion of the mixture layer, thereby covering the end portion surface of the mixture layer with a surface layer. By smoothing the lithium reactivity at the end of the mixture layer and preventing charge concentration at the end of the mixture layer, lithium deposition can be suppressed and cycle characteristics can be improved.
本発明の第３の発明は、合剤層の端部表面を覆う表面層の厚みを合剤層の端部表面以外を覆う表面層の厚み以上にすることで、合剤層の端部表面を表面層で覆うことにより、合剤層の端部のリチウム反応性を平滑化させ、合剤層の端部での電荷集中を防ぐことでリチウム析出を抑制でき、サイクル特性を向上させることができる。 3rd invention of this invention makes the thickness of the surface layer which covers the edge part surface of a mixture layer more than the thickness of the surface layer which covers other than the edge part surface of a mixture layer, The edge part surface of a mixture layer By covering the surface with a surface layer, the lithium reactivity at the end of the mixture layer can be smoothed, and lithium precipitation can be suppressed by preventing charge concentration at the end of the mixture layer, thereby improving cycle characteristics. it can.
本発明の第４の発明は、表面層の厚みを合剤層の端部に向かうにつれて徐々に厚くすることで、合剤層の端部表面を表面層で覆うことにより、合剤層の端部のリチウム反応性を平滑化させ、合剤層の端部での電荷集中を防ぐことでリチウム析出を抑制でき、サイクル特性を向上させることができる。 According to a fourth aspect of the present invention, by gradually increasing the thickness of the surface layer toward the end portion of the mixture layer, the end surface of the mixture layer is covered with the surface layer to thereby end the mixture layer. By smoothing the lithium reactivity of the part and preventing charge concentration at the end of the mixture layer, lithium precipitation can be suppressed and cycle characteristics can be improved.
本発明の第５の発明は、表面層が合剤層の端部表面および集電体を覆うことによって、充放電時の電極板の合剤層端部の脱落を防止し、合剤層端部でのリチウム析出を抑制することができる。 According to a fifth aspect of the present invention, the surface layer covers the end surface of the mixture layer and the current collector, thereby preventing the end of the mixture layer end of the electrode plate during charging and discharging. Lithium precipitation at the part can be suppressed.
本発明の第６の発明は、電極板長手方向の合剤層の両端部もしくは両端部の合剤層のどちらか一方の端部を表面層で覆うことで、合剤層の端部のリチウム反応性を平滑化させ、合剤層の端部での電荷集中を防ぐことでリチウム析出を抑制でき、サイクル特性を向上させることができる。 According to a sixth aspect of the present invention, the end portion of the mixture layer is covered with a surface layer by covering either one end of the mixture layer in the longitudinal direction of the electrode plate or the other end of the mixture layer with a surface layer. By smoothing the reactivity and preventing charge concentration at the end of the mixture layer, lithium deposition can be suppressed and cycle characteristics can be improved.
本発明の第７の発明は、電極板幅方向の合剤層の両端部もしくは両端部の合剤層のどちらか一方の端部を表面層で覆うことで、合剤層の端部のリチウム反応性を平滑化させ、合剤層の端部での電荷集中を防ぐことでリチウム析出を抑制でき、サイクル特性を向上させることができる。 The seventh invention of the present invention is to cover either one of the both end portions of the mixture layer in the electrode plate width direction or the end portion of the mixture layer with a surface layer, so that the lithium at the end portion of the mixture layer By smoothing the reactivity and preventing charge concentration at the end of the mixture layer, lithium deposition can be suppressed and cycle characteristics can be improved.
本発明の第８の発明は、表面層に、リチウムニッケル酸複合酸化物などのニッケル系複合酸化物、リチウムコバルト酸複合酸化物などのコバルト系複合酸化物、コバルト酸ナノ粒子、コバルト酸窒化物、リチウムマンガン酸複合酸化物などのマンガン系複合酸化物、リチウムクロム酸複合酸化物などのクロム系複合酸化物、リチウムリン酸鉄複合酸化物な
どのリン酸鉄系複合酸化物、五酸化バナジウムなどのバナジウム系複合酸化物、グラファイト、ハードカーボン、リチウムチタン複合酸化物などのチタン系複合酸化物、酸化スズガラス、シリカ系合金組成材料および金属リチウムのいずれかを用いることによって、電極板表面でのリチウムの反応性を平滑化させ、電極群でのリチウム析出を抑制することができる。
In an eighth aspect of the present invention, the surface layer includes a nickel-based composite oxide such as lithium nickel acid composite oxide, a cobalt-based composite oxide such as lithium cobalt acid composite oxide, cobalt acid nanoparticles, and cobalt oxynitride. , Manganese complex oxides such as lithium manganate complex oxides, chromium complex oxides such as lithium chromate complex oxides, iron phosphate complex oxides such as lithium iron phosphate complex oxides, vanadium pentoxide, etc. Lithium on the electrode plate surface by using any one of vanadium-based composite oxide, titanium-based composite oxide such as graphite, hard carbon, lithium-titanium composite oxide, tin oxide glass, silica-based alloy composition material and metallic lithium This can smoothen the reactivity and suppress lithium deposition at the electrode group.
本発明の第９の発明は、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を負極集電体の上に担持した負極板との間に多孔質絶縁体を介在させ積層または渦巻状に捲回して構成した電極群を非水系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、電極板に第１〜８のいずれかの発明に記載の非水系二次電池用電極板を用いたことにより、安全性と充放電サイクル特性に優れた非水系二次電池を得ることができる。 According to a ninth aspect of the present invention, a positive electrode mixture paint obtained 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 a positive electrode current collector. A porous insulator is interposed between the positive electrode plate on which the positive electrode mixture layer is formed and the negative electrode plate on which a negative electrode active material made of a material capable of holding at least lithium is supported. A non-aqueous secondary battery in which an electrode group formed by winding is enclosed in a battery case together with a non-aqueous electrolyte, and the electrode plate is a non-aqueous secondary battery electrode according to any one of the first to eighth aspects of the invention. By using the plate, a nonaqueous secondary battery excellent in safety and charge / discharge cycle characteristics can be obtained.
以下、本発明の実施の形態について、図面を参照しながら説明する。なお、この実施の形態によって本発明が限定されるものではない。
（実施の形態１）
図１は本発明における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１１の一部切欠斜視図を示すものである。
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.
(Embodiment 1)
FIG. 1 is a partially cutaway perspective view of a cylindrical lithium ion secondary battery 11 as an example of a non-aqueous secondary battery in the present invention.
円筒形リチウムイオン二次電池１１は、リチウム含有複合酸化物を正極活物質とする正極板１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２とを多孔質絶縁体３としてのセパレータを介して渦巻状に巻回して電極群４が作製される。 A cylindrical lithium ion secondary battery 11 includes a positive electrode plate 1 using a lithium-containing composite oxide as a positive electrode active material and a negative electrode plate 2 using a material capable of holding lithium as a negative electrode active material as a porous insulator 3. The electrode group 4 is produced by spirally winding the separator.
電極群４は、外装体である有底円筒形の電池ケース５の内部に絶縁板６により電池ケース５とは絶縁されて収容される一方で、電極群４の下部より導出した負極リード７が電池ケース５の底部に接続されるとともに、電極群４の上部より導出した正極リード８が封口板９に接続される。この渦巻状の電極群４を有底円筒形の電池ケース５の内部に収容し、次いでこの電池ケース５に所定量の非水溶媒からなる非水電解液を注液した後、電池ケース５の開口部にガスケット１０を周縁に取り付けた封口板９を挿入し、電池ケース５の開口部を内方向に折り曲げて封口している。 The electrode group 4 is housed inside a bottomed cylindrical battery case 5 that is an exterior body, insulated from the battery case 5 by an insulating plate 6, while a negative electrode lead 7 led out from the lower part of the electrode group 4 is provided. The positive electrode lead 8 led out from the upper part of the electrode group 4 is connected to the sealing plate 9 while being connected to the bottom of the battery case 5. The spiral electrode group 4 is housed inside a bottomed cylindrical battery case 5, and then a non-aqueous electrolyte composed of a predetermined amount of a non-aqueous solvent is injected into the battery case 5. A sealing plate 9 with a gasket 10 attached to the periphery is inserted into the opening, and the opening of the battery case 5 is folded inward to seal it.
図２は本発明の一実施の形態における負極板２の断面の模式図を示すものである。さらに、図３は本発明の一実施の形態における負極板２の表面の模式図を示すものである。
負極板２は、負極集電体１２の表面に、負極合剤層１３を形成してなる。この際、負極合剤層１３の負極板長手方向の両端部の厚みは、負極合剤層１３の端部に向かうにつれて薄くなるように構成されている。ここで、負極合剤層１３の端部とは、負極合剤層１３を負極集電体１２に塗り始めまたは塗り終わった位置から２０ｍｍ以下の部分をいう。
そして、両端部表面を含む負極合剤層１３の表面に、リチウムの反応性が高くリチウム析出を抑制する表面層１４を均一の厚さで塗布して、負極合剤層１３表面を表面層１４で覆うように構成する。したがって、負極合剤層１３の表層部を表面層１４で塗布端部を均一に完全に覆い隠している状態を示している。そして、負極合剤層１３の外周側端部近傍の負極集電体１２上に、負極リード７が接合されている。
FIG. 2 shows a schematic diagram of a cross section of the negative electrode plate 2 in one embodiment of the present invention. Further, FIG. 3 shows a schematic view of the surface of the negative electrode plate 2 in one embodiment of the present invention.
The negative electrode plate 2 is formed by forming a negative electrode mixture layer 13 on the surface of the negative electrode current collector 12. At this time, the thickness of both ends of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to become thinner toward the end of the negative electrode mixture layer 13. Here, the end portion of the negative electrode mixture layer 13 refers to a portion of 20 mm or less from the position at which the negative electrode mixture layer 13 starts to be applied to the negative electrode current collector 12 or has been applied.
Then, a surface layer 14 that has high lithium reactivity and suppresses lithium precipitation is applied to the surface of the negative electrode mixture layer 13 including both end surfaces with a uniform thickness, so that the surface of the negative electrode mixture layer 13 is the surface layer 14. It is configured to cover with. Accordingly, the surface layer portion of the negative electrode mixture layer 13 is covered with the surface layer 14 so that the coating end portion is completely and completely covered. The negative electrode lead 7 is bonded onto the negative electrode current collector 12 in the vicinity of the outer peripheral side end of the negative electrode mixture layer 13.
負極活物質として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.
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バインダー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したり少量添加するのがより好ましいといえる。
Various binders such as PVdF and modified products thereof can be used as the binder for the negative electrode. From the viewpoint of improving lithium ion acceptability, styrene-butadiene copolymer rubber particles (SBR) and modified products thereof are added to carboxy. It can be said that it is more preferable to use a cellulose resin such as methylcellulose (CMC) or the like in combination or to add a small amount.
次に表面層１４の活物質と導電剤および結着材を適切な分散媒中に入れ、プラネタリーミキサー等の分散機により混合分散して、負極合剤層１３への塗布に最適な粘度に調整して混練を行い、表面層１４に塗布する塗料を作製した。 Next, the active material of the surface layer 14, the conductive agent, and the binder are put in an appropriate dispersion medium, and mixed and dispersed by a dispersing machine such as a planetary mixer to obtain an optimum viscosity for application to the negative electrode mixture layer 13. Adjustment was performed and kneading was performed to prepare a coating applied to the surface layer 14.
表面層１４の活物質として、リチウムチタン複合酸化物などのチタン系複合酸化物および各種合金組成材料を用いることができる。このとき、表面層１４の活物質として使用する複合酸化物の粒子径が合剤層の活物質として使用する黒鉛、シリコン系複合材料、および各種合金組成材料よりも小さく、粒子表面積が大きいために負極合剤層１３や負極集電体１２との接触面積が増え、結着性が高くなる。
一方、表面層結着材としては負極結着材と同様にＰＶｄＦおよびその変性体をはじめ各種バインダー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したり、少量添加するのがより好ましいといえる。
As the active material of the surface layer 14, titanium-based composite oxides such as lithium titanium composite oxide and various alloy composition materials can be used. At this time, the particle diameter of the composite oxide used as the active material of the surface layer 14 is smaller than that of graphite, silicon composite materials, and various alloy composition materials used as the active material of the mixture layer, and the particle surface area is large. The contact area with the negative electrode mixture layer 13 and the negative electrode current collector 12 increases, and the binding property increases.
On the other hand, as the surface layer binder, PVdF and its various modified binders can be used in the same manner as the negative electrode binder. From the viewpoint of improving lithium ion acceptability, styrene-butadiene copolymer rubber particles ( It can be said that it is more preferable to use a cellulose resin such as carboxymethylcellulose (CMC) in combination with SBR) and its modified product, or to add a small amount thereof.
このときの導電材としては、例えばアセチレンブラック、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラック等のカーボンブラックやカーボンナノチューブ、ＶＧＣＦなど各種グラファイトを単独、あるいは組み合わせて用いても良い。 As the conductive material at this time, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and various graphites such as carbon nanotubes and VGCF may be used alone or in combination.
上記のように作製した負極合剤塗料と表面層塗料を銅箔の負極集電体１２の上に負極合剤層１３を塗布し、さらに負極合剤層１３の表面にダイコーターにて表面層１４を塗布乾燥後プレスにて所定厚みまで圧縮し、所定の負極板２を得ることができる。そして、群構成する際の捲き外側の前記合剤層の端部近傍の集電体１２上に、負極リード７を接合する。 The negative electrode mixture paint and the surface layer paint produced as described above were applied on the negative electrode current collector 12 made of copper foil, and the surface layer of the negative electrode mixture layer 13 was further coated with a die coater. 14 is applied and dried, and then compressed to a predetermined thickness by a press, whereby a predetermined negative electrode plate 2 can be obtained. Then, the negative electrode lead 7 is bonded onto the current collector 12 in the vicinity of the end portion of the mixture layer on the outer side when forming the group.
正極板１については、正極活物質として、例えばコバルト酸リチウムおよびその変性体（コバルト酸リチウムにアルミニウムやマグネシウムを固溶させたものなど）、ニッケル酸リチウムおよびその変性体（一部ニッケルをコバルト置換させたものなど）、マンガン酸リチウムおよびその変性体などの複合酸化物を挙げることができる。 For the positive electrode plate 1, as the positive electrode active material, for example, lithium cobaltate and modified products thereof (such as lithium cobaltate in which aluminum or magnesium is dissolved), lithium nickelate and modified products thereof (partially nickel is substituted with cobalt) And composite oxides such as lithium manganate and modified products thereof.
このときの導電材としては、例えばアセチレンブラック、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラック等のカーボンブラック、各種グラファイトを単独、あるいは組み合わせて用いても良い。 As the conductive material at this time, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, and various graphites may be used alone or in combination.
また、正極用結着材としては、例えばポリフッ化ビニリデン（ＰＶｄＦ）、ポリフッ化ビニリデンの変性体、ポリテトラフルオロエチレン（ＰＴＦＥ）、アクリレート単位を有するゴム粒子結着材などを用いることができ、この際に反応性官能基を導入したアクリレートモノマー、またはアクリレートオリゴマーを結着材中に混入させることも可能である。 As the positive electrode binder, for example, polyvinylidene fluoride (PVdF), a modified polyvinylidene fluoride, polytetrafluoroethylene (PTFE), a rubber particle binder having an acrylate unit, and the like can be used. In this case, an acrylate monomer or an acrylate oligomer into which a reactive functional group is introduced may be mixed in the binder.
非水電解液については、電解質塩としてＬｉＰＦ６およびＬｉＢＦ４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（ＭＥＣ）を単独および組み合わせて用いることができる。また正負極板上に良好な皮膜を形成させたり、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。
多孔質絶縁体３としてのセパレータについては、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。この多孔質絶縁体３としてのセパレータの厚みは特に限定されないが、１０〜２５μｍとすれば良い。
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), and methyl ethyl carbonate (MEC) 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 electrode plates and to ensure stability during overcharge.
The separator as the porous insulator 3 is not particularly limited as long as it has a composition that can withstand the range of use of the lithium ion secondary battery. However, a microporous film of an olefin-based resin such as polyethylene / polypropylene can be used alone or in combination. It is generally used as a preferred embodiment. The thickness of the separator as the porous insulator 3 is not particularly limited, but may be 10 to 25 μm.
以上のように構成された非水系二次電池について、以下、その動作、作用を説明する。正極板１と負極板２を多孔質絶縁体３で介在させ渦巻状に捲回して構成した電極群４において、電極群４の外周側の負極集電体１２上に、負極リード７が接合されている。そのため、負極合剤層１３の電極群４の外周側端部には、電荷が集中しリチウムが析出しやすい。また、正極板１と負極板２を多孔質絶縁体３で介在させ渦巻状に捲回して電極群４を形成する際には、電極群４の内周側を、電極群４の外周側よりも張力をかけて捲回しなければならない。そのため、電極群４内周側の正極板１と負極板２との距離は、電極群４の外周側の正極板１と負極板２との距離よにも近くなり、負極合剤層１３の電極群４の内周側端部には、リチウムが析出しやすい。 About the non-aqueous secondary battery comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. In an electrode group 4 configured by winding a positive electrode plate 1 and a negative electrode plate 2 with a porous insulator 3 and winding them in a spiral shape, a negative electrode lead 7 is joined on a negative electrode current collector 12 on the outer peripheral side of the electrode group 4. ing. Therefore, electric charges concentrate on the outer peripheral side end of the electrode group 4 of the negative electrode mixture layer 13 and lithium is likely to be deposited. Further, when the electrode group 4 is formed by winding the positive electrode plate 1 and the negative electrode plate 2 with the porous insulator 3 in a spiral shape, the inner peripheral side of the electrode group 4 is changed from the outer peripheral side of the electrode group 4. Must be wound with tension. Therefore, the distance between the positive electrode plate 1 and the negative electrode plate 2 on the inner peripheral side of the electrode group 4 is closer to the distance between the positive electrode plate 1 and the negative electrode plate 2 on the outer peripheral side of the electrode group 4. Lithium tends to be deposited at the inner peripheral side end of the electrode group 4.
しかしながら、負極合剤層１３の両端部の厚みを負極合剤層１３の両端部以外の厚みよりも薄くするとともに、負極合剤層１３の両端部表面をリチウムの反応性が高くリチウム析出を抑制する表面層１４で覆うことで、局所的なリチウム析出を抑制できる。
（実施の形態２）
図４は本発明の第２の実施の形態における非水系二次電池用負極板２の断面の模式図である。負極板２は、負極集電体１２の表面に、活物質の負極合剤層１３を形成してなる。この際、負極板長手方向の負極合剤層１３の両端部の厚みは、負極合剤層１３の端部に向かうにつれて薄くなるように構成されている。そして、負極合剤層１３の両端部表面を含む負極合剤層１３の表面に、リチウムの反応性が高くリチウム析出を抑制する表面層１４を、負極合剤層１３の端部に向かうにつれて厚くなるように塗布して、負極合剤層１３の表面を表面層１４で覆うように構成する。したがって、負極合剤層１３の表層部を表面層１４で塗布端部を完全に覆い隠している状態を示している。
以上のように構成された非水系二次電池用負極板２は、表面層１４を、負極合剤層１３の端部に向かうにつれて厚くなるように塗布することにより、負極合剤層１３の両端部のリチウム反応性を向上させることができ、良好なサイクル特性を得ることができる。
（実施の形態３）
図５は本発明の第３の実施の形態における非水系二次電池用負極板２の断面の模式図である。負極板２は、負極集電体１２の表面に、負極合剤層１３を形成してなる。この際、負極板長手方向の負極合剤層１３の端部の厚みは、負極合剤層１３の端部に向かうにつれて薄くなるように構成されている。そして、負極合剤層１３の端部表面を含む合剤層表面に、リチウムの反応性が高くリチウム析出を抑制する表面層１４を、負極合剤層１３の端部に向かうにつれて厚くなるように塗布するとともに、負極合剤層１３の端部表面だけでなく負極集電体１２をも覆うように構成する。
以上のように構成された非水系二次電池用負極板は、負極合剤層１３の両端部のリチウム反応性を向上させることができるとともに、負極合剤層１３の端部表面および負極集電体１２を覆うことにより結着性の高い表面層１４を負極集電体１２と接触させることができ、充放電時の負極板２の収縮による端部の合剤脱落を防止でき、良好なサイクル特性を得ることができる。
However, the thickness of both ends of the negative electrode mixture layer 13 is made thinner than the thickness of the negative electrode mixture layer 13 other than both ends, and the surface of both ends of the negative electrode mixture layer 13 has high lithium reactivity and suppresses lithium precipitation. By covering with the surface layer 14 to perform, local lithium precipitation can be suppressed.
(Embodiment 2)
FIG. 4 is a schematic view of a cross section of the negative electrode plate 2 for a non-aqueous secondary battery according to the second embodiment of the present invention. The negative electrode plate 2 is formed by forming a negative electrode mixture layer 13 of an active material on the surface of a negative electrode current collector 12. At this time, the thickness of both end portions of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to become thinner toward the end portion of the negative electrode mixture layer 13. Then, the surface layer 14 that has high lithium reactivity and suppresses lithium precipitation on the surface of the negative electrode mixture layer 13 including the surfaces of both end portions of the negative electrode mixture layer 13 becomes thicker toward the end of the negative electrode mixture layer 13. The surface of the negative electrode mixture layer 13 is covered with the surface layer 14. Therefore, the surface layer portion of the negative electrode mixture layer 13 is completely covered and covered with the surface layer 14.
The negative electrode plate 2 for a non-aqueous secondary battery configured as described above is applied to the both ends of the negative electrode mixture layer 13 by applying the surface layer 14 so as to increase in thickness toward the end of the negative electrode mixture layer 13. The lithium reactivity of the part can be improved, and good cycle characteristics can be obtained.
(Embodiment 3)
FIG. 5 is a schematic view of a cross section of the negative electrode plate 2 for a non-aqueous secondary battery in the third embodiment of the present invention. The negative electrode plate 2 is formed by forming a negative electrode mixture layer 13 on the surface of the negative electrode current collector 12. At this time, the thickness of the end portion of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to become thinner toward the end portion of the negative electrode mixture layer 13. Then, on the surface of the mixture layer including the surface of the end portion of the negative electrode mixture layer 13, the surface layer 14 having high lithium reactivity and suppressing lithium precipitation is made thicker toward the end portion of the negative electrode mixture layer 13. In addition to coating, it is configured to cover not only the end surface of the negative electrode mixture layer 13 but also the negative electrode current collector 12.
The negative electrode plate for a non-aqueous secondary battery configured as described above can improve the lithium reactivity at both ends of the negative electrode mixture layer 13, and the end surface of the negative electrode mixture layer 13 and the negative electrode current collector. By covering the body 12, the surface layer 14 having a high binding property can be brought into contact with the negative electrode current collector 12, and it is possible to prevent the end mixture from falling off due to the contraction of the negative electrode plate 2 during charge and discharge, and a good cycle Characteristics can be obtained.
なお、本実施の形態では、負極合剤層１３の両端部の厚みを前記合剤層の端部以外の厚みよりも薄くしているが、負極合剤層１３の一方端部の厚みを負極合剤層１３の端部以外の厚みよりも薄くしてもよい。
さらに、負極板長手方向の負極合剤層１３の両端部の厚みは、両端部以外の部分よりも薄くなるように構成したが、図６で示すように、負極板２の幅方向の負極合剤層１３の両端部の厚みを、両端部以外の部分よりも薄くなるように構成してもよい。この際、負極合剤
層１３を塗布した部分と、負極合剤層１３を塗布していない部分を設け、負極集電体１２の幅方向で合剤層１３を塗布していない部分にリード７を接合してもよい。
In the present embodiment, the thickness of both end portions of the negative electrode mixture layer 13 is made thinner than the thickness other than the end portions of the mixture layer, but the thickness of one end portion of the negative electrode mixture layer 13 is made negative. You may make it thinner than thickness other than the edge part of the mixture layer 13. FIG.
Furthermore, although the thickness of the both ends of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to be thinner than the portions other than the both ends, the negative electrode mixture in the width direction of the negative electrode plate 2 as shown in FIG. You may comprise so that the thickness of the both ends of the agent layer 13 may become thinner than parts other than both ends. At this time, a portion where the negative electrode mixture layer 13 is applied and a portion where the negative electrode mixture layer 13 is not applied are provided, and the lead 7 is provided in a portion where the mixture layer 13 is not applied in the width direction of the negative electrode current collector 12. May be joined.
本実施の形態では、正極板１と負極板２との間に多孔質絶縁体３を介在させ渦巻状に捲回して電極群４を形成したが、積層して電極群４を形成してもよい。 In the present embodiment, the electrode group 4 is formed by interposing the porous insulator 3 between the positive electrode plate 1 and the negative electrode plate 2 and winding it in a spiral shape. Good.
また、本実施の形態では負極合剤層１３の上に表面層１４が形成される例を示したが、表面層を形成するのは正負極いずれでもよい。
以下、本発明における非水系二次電池用電極板２およびこれを用いた非水系二次電池１１の一実施の形態を示す。
Moreover, although the example in which the surface layer 14 is formed on the negative electrode mixture layer 13 has been described in the present embodiment, the positive and negative electrodes may be formed to form the surface layer.
Hereinafter, an embodiment of a non-aqueous secondary battery electrode plate 2 and a non-aqueous secondary battery 11 using the same according to the present invention will be described.
図２に示したものと同じ構造の負極板を用いた非水系二次電池１１を作製した実施例１について説明する。 Example 1 in which a nonaqueous secondary battery 11 using a negative electrode plate having the same structure as that shown in FIG. 2 was produced will be described.
まず、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。さらに、表面層の活物質としてリチウムチタン複合酸化物を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％）を表面層の活物質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表面層の活物質１００重量部に対して１重量部、導電材としてアセチレンブラックを、表面層活物質１００重量部に対して３．０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、表面層塗料を作製した。これらの塗料をはじめに１０μｍ厚の銅箔からなる負極集電体１２に負極合剤塗料を塗布乾燥し、次いで負極合剤塗料の表層部に表面層塗料を負極合剤層１００重量部に対して２０重量部となるように塗布乾燥し、総厚が２００μｍとなるようにプレスし、負極板２を作製した。 First, 100 parts by weight of artificial graphite as a negative electrode active material, and 2.5 parts by weight of styrene-butadiene copolymer rubber particle dispersion (solid content 40% by weight) as a 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. Further, 100 parts by weight of lithium titanium composite oxide as the active material for the surface layer, and styrene-butadiene copolymer rubber particle dispersion (solid content 40% by weight) as the binder for 100 parts by weight of the active material for the surface layer. 2.5 parts by weight (1 part by weight in terms of solid content of the binder), carboxymethyl cellulose as a thickener, 1 part by weight with respect to 100 parts by weight of the active material of the surface layer, acetylene black as the conductive material, surface The mixture was stirred with a double arm kneader together with 3.0 parts by weight of water and 100 parts by weight of the layered active material to prepare a surface layer paint. First, a negative electrode mixture paint is applied to and dried on a negative electrode current collector 12 made of a copper foil having a thickness of 10 μm, and then the surface layer paint is applied to the surface layer portion of the negative electrode mixture paint with respect to 100 parts by weight of the negative electrode mixture layer. The coating was dried to 20 parts by weight, and pressed to a total thickness of 200 μm to prepare the negative electrode plate 2.
このとき、負極板長手方向の負極合剤層１３の両端部の厚みは、負極合剤層１３の端部に向かうにつれて薄くなるように構成するとともに、負極合剤層１３の両端部表面を含む合剤層表面に、リチウムの反応性が高くリチウム析出を抑制する表面層１４を均一の厚さで塗布して、負極合剤層１３表面を表面層１４で完全に覆うように構成する。 At this time, the thickness of the both ends of the negative electrode mixture layer 13 in the longitudinal direction of the negative electrode plate is configured to become thinner toward the end of the negative electrode mixture layer 13 and includes the surfaces of both ends of the negative electrode mixture layer 13. A surface layer 14 having a high lithium reactivity and suppressing lithium precipitation is applied to the surface of the mixture layer with a uniform thickness so that the surface of the negative electrode mixture layer 13 is completely covered with the surface layer 14.
一方、正極活物質としてコバルト酸リチウムを１００重量部、導電材としてアセチレンブラックを正極活物質１００重量部に対して２重量部、結着材としてポリフッ化ビニリデンを正極活物質１００重量部に対して２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。この塗料を１５μｍ厚のアルミニウム箔からなる正極集電体に塗布乾燥し、総厚が１７０μｍとなるようにプレスした。 Meanwhile, 100 parts by weight of lithium cobaltate as a positive electrode active material, 2 parts by weight of acetylene black as a conductive material with respect to 100 parts by weight of the positive electrode active material, and polyvinylidene fluoride as a binder with respect to 100 parts by weight of the positive electrode active material. A positive electrode mixture paint was prepared by stirring and kneading 2 parts by weight with an appropriate amount of N-methyl-2-pyrrolidone in a double-arm kneader. This paint was applied to a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried, and pressed to a total thickness of 170 μm.
さらに、図１に示すように、これらの正極板１および負極板２を２０μｍ厚のポリエチレン微多孔フィルムを多孔質絶縁体３としてのセパレータとして巻回し電極群４を構成し、所定の長さで切断して電池ケース５の内に挿入し、ＥＣ・ＤＭＣ・ＭＥＣ混合溶媒にＬｉＰＦ6を１ＭとＶＣを３重量部溶解させた非水電解液を、５．５ｇ添加して封口し作製した円筒形リチウムイオン二次電池１１を実施例１とした。 Further, as shown in FIG. 1, the positive electrode plate 1 and the negative electrode plate 2 are wound using a polyethylene microporous film having a thickness of 20 μm as a separator as a porous insulator 3 to form an electrode group 4, which has a predetermined length. Cut and inserted into the battery case 5 and sealed by adding 5.5 g of a nonaqueous electrolytic solution in which 3 parts by weight of LiPF6 and 3 parts by weight of VC were dissolved in a mixed solvent of EC, DMC and MEC. The lithium ion secondary battery 11 was taken as Example 1.
実施例１との違いは、電極群４内周側の負極合剤層１３端部が表面層１４で完全に覆わ
れるように塗布し、電極群４外周側の負極合剤層１３端部が表面層１４で覆われていない負極板２を得たことである。実施例１と同様の方法で負極合剤塗料と表面層塗料を作製し、合剤塗料を１０μｍ厚の銅箔からなる負極集電体１２に塗布乾燥して形成する負極合剤層１００重量部に対して表面層塗料を２０重量部となるように塗布乾燥し、総厚が２００μｍとなるようにプレスし、負極板２を作製した。
一方、実施例１と同様の正極板１を作製し、これらの正極板１および負極板２を実施例１と同様の方法で作製した円筒形リチウムイオン二次電池１１を実施例２とした。
このとき、負極合剤層１３が表面層１４で完全に覆われている一端部は電極群４を構成する際に、内周側になるように構成し、所定の長さで切断して電池ケース５の内に挿入し、非水電解液を、５．５ｇ添加して封口し作製した円筒形リチウムイオン二次電池１１を実施例２とした。
The difference from Example 1 is that the end of the negative electrode mixture layer 13 on the inner peripheral side of the electrode group 4 is applied so that it is completely covered with the surface layer 14, and the end of the negative electrode mixture layer 13 on the outer peripheral side of the electrode group 4 is That is, the negative electrode plate 2 not covered with the surface layer 14 was obtained. 100 parts by weight of a negative electrode mixture layer formed by preparing a negative electrode mixture paint and a surface layer paint in the same manner as in Example 1, and applying and drying the mixture paint onto a negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. Then, the surface layer coating was applied and dried so as to be 20 parts by weight, and pressed so that the total thickness became 200 μm, and the negative electrode plate 2 was produced.
On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 2.
At this time, the one end part where the negative electrode mixture layer 13 is completely covered with the surface layer 14 is formed so as to be on the inner peripheral side when the electrode group 4 is formed, and the battery is cut by a predetermined length. The cylindrical lithium ion secondary battery 11 inserted into the case 5 and sealed by adding 5.5 g of a non-aqueous electrolyte was used as Example 2.
実施例１との違いは、電極群４外周側の負極合剤層１３の端部が表層部に設けた表面層で完全に覆われるように塗布し、電極群４内周側の負極合剤層１３の端部が表面層１４で覆われていない負極板２を得たことである。実施例１と同様の方法で負極合剤塗料と表面層塗料を作製し、合剤塗料を１０μｍ厚の銅箔からなる負極集電体１２に塗布乾燥して形成する負極合剤層１００重量部に対して表面層塗料を２０重量部となるように塗布乾燥し、総厚が２００μｍとなるようにプレスし、負極板２を作製した。
一方、実施例１と同様の正極板１を作製し、これらの正極板１および負極板２を実施例１と同様の方法で作製した円筒形リチウムイオン二次電池１１を実施例３とした。
このとき、負極合剤層１３が表面層１４で完全に覆われている一端部は電極群４を構成する際に、外周側になるように構成し、所定の長さで切断して電池ケース５の内に挿入し、非水電解液を、５．５ｇ添加して封口し作製した円筒形リチウムイオン二次電池１１を実施例３とした。
The difference from Example 1 is that the end of the negative electrode mixture layer 13 on the outer peripheral side of the electrode group 4 is applied so that it is completely covered with the surface layer provided on the surface layer part, and the negative electrode mixture on the inner peripheral side of the electrode group 4 That is, the negative electrode plate 2 in which the end portion of the layer 13 is not covered with the surface layer 14 is obtained. 100 parts by weight of a negative electrode mixture layer formed by preparing a negative electrode mixture paint and a surface layer paint in the same manner as in Example 1, and applying and drying the mixture paint onto a negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. Then, the surface layer coating was applied and dried so as to be 20 parts by weight, and pressed so that the total thickness became 200 μm, and the negative electrode plate 2 was produced.
On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 3.
At this time, one end of the negative electrode mixture layer 13 that is completely covered with the surface layer 14 is configured to be on the outer peripheral side when the electrode group 4 is formed, and is cut to a predetermined length to form a battery case. Example 3 was a cylindrical lithium ion secondary battery 11 that was inserted into 5 and sealed by adding 5.5 g of a non-aqueous electrolyte.
図４に示したのと同じ構造の負極板２を用いた非水系二次電池１１を作製した。実施例１と同様の方法で負極合剤塗料と表面層塗料を作製し、負極合剤塗料を１０μｍ厚の銅箔からなる負極集電体１２に形成する負極合剤層１００重量部に対して表面層塗料を２０重量部となるように乾燥前に同時タイミングでこれらの塗料を塗布し、その後乾燥させた後、総厚が２００μｍとなるようにプレスし、負極板２を作成した。このとき始端部および終端部で表面層１４を形成する際のダイコーターの吐出圧力を上げることで端部の表面層１４の膜厚を徐々に厚くし、目的の負極板２を得た。 A non-aqueous secondary battery 11 using the negative electrode plate 2 having the same structure as shown in FIG. 4 was produced. A negative electrode mixture paint and a surface layer paint are produced in the same manner as in Example 1, and the negative electrode mixture paint is formed on the negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. These paints were applied at the same time before drying so that the surface layer paint was 20 parts by weight, and then dried, and then pressed to a total thickness of 200 μm to prepare the negative electrode plate 2. At this time, by increasing the discharge pressure of the die coater at the time of forming the surface layer 14 at the start end portion and the end portion, the film thickness of the surface layer 14 at the end portion was gradually increased to obtain the target negative electrode plate 2.
一方、実施例１と同様の正極板１を作製し、これらの正極板１および負極板２を実施例１と同様の方法で作製した円筒形リチウムイオン二次電池１１を実施例４とした。 On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 4.
図５に示したのと同じ構造の負極板２を用いた非水系二次電池１１を作製した。実施例１と同様の方法で負極合剤塗料と表面層塗料を作製し、負極合剤塗料を１０μｍ厚の銅箔からなる負極集電体１２に形成する負極合剤層１００重量部に対して表面層塗料を２０重量部となるように塗布し、その後乾燥させた後、総厚が２００μｍとなるようにプレスし、負極板２を作成した。このとき始端部および終端部で表面層１４を形成する際のダイコーターの吐出タイミングをずらすことで端部の表面層１４が単一層として負極集電体１２に接着する箇所を設け、目的の負極板２を得た。 A non-aqueous secondary battery 11 using the negative electrode plate 2 having the same structure as that shown in FIG. 5 was produced. A negative electrode mixture paint and a surface layer paint are produced in the same manner as in Example 1, and the negative electrode mixture paint is formed on the negative electrode current collector 12 made of a copper foil having a thickness of 10 μm. The surface layer coating material was applied to 20 parts by weight and then dried, and then pressed to a total thickness of 200 μm to prepare the negative electrode plate 2. At this time, by shifting the discharge timing of the die coater when forming the surface layer 14 at the start end portion and the end portion, a location where the end surface layer 14 adheres to the negative electrode current collector 12 as a single layer is provided. Plate 2 was obtained.
一方、実施例１と同様の正極板１を作製し、これらの正極板１および負極板２を実施例１と同様の方法で作製した円筒形リチウムイオン二次電池１１を実施例５とした。 On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Example 5.
（比較例１）
図７は比較例における非水系二次電池用負極板２の断面の模式図であり、少なくとも負極活物質および結着材より構成される負極合剤塗料と機能性活物質および導電材と結着材からなる表面層１４を負極集電体１２の上に塗布乾燥させて形成される。このとき、図２と同様に表面層１４が負極合剤層１３の表層部に形成されるが、図７は表面層１４を塗布する際のタイミングをずらすことで負極合剤層１３の両端部で、負極合剤層１３が露出する状態を示している。
(Comparative Example 1)
FIG. 7 is a schematic diagram of a cross-section of the negative electrode plate 2 for a non-aqueous secondary battery in a comparative example, and a negative electrode mixture paint composed of at least a negative electrode active material and a binder, a functional active material, and a conductive material. A surface layer 14 made of a material is formed on the negative electrode current collector 12 by drying. At this time, the surface layer 14 is formed on the surface layer portion of the negative electrode mixture layer 13 as in FIG. 2, but FIG. 7 shows both ends of the negative electrode mixture layer 13 by shifting the timing when the surface layer 14 is applied. In this state, the negative electrode mixture layer 13 is exposed.
実施例１と同様の方法で負極合剤塗料と表面層塗料を作製し、この塗料を１０μｍ厚の銅箔からなる負極集電体１２に塗布乾燥し、総厚が２００μｍとなるようにプレスし、図７に示した一端部が一部負極合剤層１３を覆わない負極板２を得た。 A negative electrode mixture paint and a surface layer paint were prepared in the same manner as in Example 1. The paint was applied to a negative electrode current collector 12 made of 10 μm thick copper foil, and pressed to a total thickness of 200 μm. The negative electrode plate 2 in which one end portion shown in FIG. 7 did not partially cover the negative electrode mixture layer 13 was obtained.
一方、実施例１と同様の正極板１を作製し、これらの正極板１および負極板２を実施例１と同様の方法で作製した円筒形リチウムイオン二次電池１１を比較例１とした。 On the other hand, a positive electrode plate 1 similar to that in Example 1 was produced, and a cylindrical lithium ion secondary battery 11 in which these positive electrode plate 1 and negative electrode plate 2 were produced in the same manner as in Example 1 was used as Comparative Example 1.
そして、上記の条件で作成された円筒形リチウムイオン二次電池１１について、以下の内容でサイクル特性について評価を行った。５００サイクル後の容量維持率としては、封口後の完成電池について慣らし充放電を2回行い、４５℃環境で７日間保存した後、以下の充放電サイクルを５００回繰り返した。 And about the cylindrical lithium ion secondary battery 11 created on said conditions, the cycle characteristics were evaluated by the following content. As the capacity maintenance rate after 500 cycles, the completed battery after sealing was conditioned and discharged twice and stored for 7 days in a 45 ° C. environment, and then the following charge / discharge cycle was repeated 500 times.
ここで、充電については定電圧４．２Ｖ、１４００ｍＡで充電を行い、充電電流が１００ｍＡまで低下したとき充電を終了し、放電は２０００ｍＡの定電流で終止電圧３Ｖまで放電することを１サイクルとして、１サイクル目に対する５００サイクル目の放電容量比を５００サイクル後の容量維持率として測定を行った。さらに、充放電サイクルを５００回繰り返した後に電極群内部でのリチウム析出の状態を観察した。 Here, charging is performed at a constant voltage of 4.2 V and 1400 mA, and when the charging current is reduced to 100 mA, the charging is terminated, and discharging is performed at a constant current of 2000 mA to a final voltage of 3 V as one cycle. The discharge capacity ratio of the 500th cycle to the first cycle was measured as the capacity retention rate after 500 cycles. Furthermore, after repeating the charge / discharge cycle 500 times, the state of lithium deposition inside the electrode group was observed.
以上の項目について評価した内容を（表１）に示す。 The contents evaluated for the above items are shown in (Table 1).
（表１）に示したように、負極合剤層１３端部を表面層１４で覆うことで、合剤層１３端部のリチウム析出を抑制でき、５００サイクル後の電池容量の維持率は高い。さらに、実施例２、３にように負極合剤層１３の一方の端部を表面層１４で覆うことで内周側端部または外周側端部の負極合剤層１３のリチウム析出を抑制できるが、外周側に位置する負極合剤層１３の端部を表面層１４で覆う方が内周側に位置する負極合剤層１３端部を表面
層１４で覆うよりも５００サイクル後の電池容量の維持率は高くなる。これは、負極リード７の位置が負極合剤層１３外周側近傍の負極集電体１２に設置されているためにリチウム析出しやすい集電部近傍での抑制効果が大きいと推定できる。
As shown in Table 1, by covering the end portion of the negative electrode mixture layer 13 with the surface layer 14, lithium deposition at the end portion of the mixture layer 13 can be suppressed, and the battery capacity retention rate after 500 cycles is high. . Furthermore, as in Examples 2 and 3, covering one end of the negative electrode mixture layer 13 with the surface layer 14 can suppress lithium precipitation of the negative electrode mixture layer 13 at the inner peripheral side end or the outer peripheral side end. However, the battery capacity after 500 cycles is that the end portion of the negative electrode mixture layer 13 located on the outer peripheral side is covered with the surface layer 14 than the end portion of the negative electrode mixture layer 13 located on the inner peripheral side is covered with the surface layer 14. The maintenance rate is high. It can be estimated that this is because the position of the negative electrode lead 7 is installed in the negative electrode current collector 12 in the vicinity of the outer periphery of the negative electrode mixture layer 13, so that the suppression effect in the vicinity of the current collecting portion where lithium is likely to precipitate is large.
また、負極合剤層１３端部での表面層１４の厚みを徐々に増やした実施例４でのリチウム析出は実施例１と同様に抑制されていた。５００サイクル後の電池容量の維持率は実施例１よりも良化し、内周側および外周側での表面層１４の作用が、表面層１４の厚みを増やすことで促進されたと推定できる。 Moreover, the lithium precipitation in Example 4 which gradually increased the thickness of the surface layer 14 at the end portion of the negative electrode mixture layer 13 was suppressed as in Example 1. It can be estimated that the maintenance rate of the battery capacity after 500 cycles is better than that of Example 1, and the action of the surface layer 14 on the inner peripheral side and the outer peripheral side is promoted by increasing the thickness of the surface layer 14.
そして、表面層１４を負極合剤層１３の端部および負極集電体１２に結着させた実施例５でのリチウム析出は実施例１と同様に抑制されていた。さらに、５００サイクル後の電池容量の維持率は実施例１よりも良化し、内周側および外周側での表面層１４の作用が促進されたと同時に表面層１４と負極集電体１２との結着力が高く、負極合剤層１３の端部の合剤脱落も防止できたと推定できる。 The lithium deposition in Example 5 in which the surface layer 14 was bound to the end of the negative electrode mixture layer 13 and the negative electrode current collector 12 was suppressed in the same manner as in Example 1. Furthermore, the maintenance rate of the battery capacity after 500 cycles was improved from that in Example 1, and the action of the surface layer 14 on the inner and outer peripheral sides was promoted, and at the same time, the connection between the surface layer 14 and the negative electrode current collector 12 was increased. It can be estimated that the adhering force was high and the mixture mixture at the end of the negative electrode mixture layer 13 was prevented from falling off.
一方で、比較例１で示されるように、負極合剤層１３の両端部を表面層１４で覆わない場合、負極合剤層１３の内周側端部と外周側端部でリチウムが析出し、５００サイクル後の電池容量の維持率は低下した。
以上、負極合剤層１３の端部を表面層１４で覆うことによって、負極合剤層１３の端部におけるリチウム析出を抑制することができ、さらに、結着力の高い表面層１４と負極集電体１２を接触させることで負極合剤層１３の端部の合剤脱落も防止でき、５００サイクル後の電池容量の維持率が向上したものと推定できる。
なお、実施例１〜５においては、負極板２の負極合剤層１３の表面層１４を設けることでリチウムの反応性を向上させたが、この方法に限定されるものではなく、例えば、正極板１の正極合剤層に表面層を設けてリチウム反応性を向上させることで同様の効果を得ることができる。
On the other hand, as shown in Comparative Example 1, when both ends of the negative electrode mixture layer 13 are not covered with the surface layer 14, lithium is deposited at the inner peripheral side end and the outer peripheral side end of the negative electrode mixture layer 13. The maintenance rate of the battery capacity after 500 cycles decreased.
As described above, by covering the end portion of the negative electrode mixture layer 13 with the surface layer 14, lithium deposition at the end portion of the negative electrode mixture layer 13 can be suppressed, and the surface layer 14 having a high binding force and the negative electrode current collector can be suppressed. By bringing the body 12 into contact with each other, it is possible to prevent the mixture from falling off at the end of the negative electrode mixture layer 13 and to improve the battery capacity retention rate after 500 cycles.
In Examples 1 to 5, the reactivity of lithium was improved by providing the surface layer 14 of the negative electrode mixture layer 13 of the negative electrode plate 2, but the method is not limited to this method. A similar effect can be obtained by providing a surface layer on the positive electrode mixture layer of the plate 1 to improve lithium reactivity.
本発明に係る非水系二次電池用電極板は、電極合剤層における端部を表面層で覆うことで、従来の非水系二次電池より電極板の端部での局所的な電荷集中を抑えることができ、充放電サイクル特性に優れているので、電子機器および通信機器の多機能化や電気自動車への応用に伴って長寿命化が望まれているポータブル用電源やＥＶ用電源等として有用である。 The electrode plate for a non-aqueous secondary battery according to the present invention covers the end portion of the electrode mixture layer with a surface layer, so that local charge concentration at the end portion of the electrode plate is more than that of the conventional non-aqueous secondary battery. As it can be suppressed and has excellent charge / discharge cycle characteristics, it can be used as a portable power supply or EV power supply that is expected to have a long life with the application of multi-function electronic devices and communication devices and electric vehicles. Useful.
１ 正極板
２ 負極板
３ 多孔質絶縁体
４ 電極群
５ 電池ケース
６ 絶縁板
７ 負極リード
８ 正極リード
９ 封口板
１０ 封口ガスケット
１１ リチウムイオン二次電池
１２ 負極集電体
１３ 負極合剤層
１４ 表面層
DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Porous insulator 4 Electrode group 5 Battery case 6 Insulating plate 7 Negative electrode lead 8 Positive electrode lead 9 Sealing plate 10 Sealing gasket 11 Lithium ion secondary battery 12 Negative electrode collector 13 Negative electrode mixture layer 14 Surface layer
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| PCT/JP2012/005442 WO2013031213A1 (en) | 2011-08-29 | 2012-08-29 | Electrode plate for non-aqueous secondary battery and non-aqueous secondary battery using same |
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| WO2016121734A1 (en) * | 2015-01-30 | 2016-08-04 | Ｎｅｃエナジーデバイス株式会社 | Secondary battery |
| JP2017157515A (en) * | 2016-03-04 | 2017-09-07 | 株式会社Ｇｓユアサ | Power storage element |
| CN109841794A (en) * | 2019-03-29 | 2019-06-04 | 宁德新能源科技有限公司 | Electrode plates and electrochemical appliance comprising the electrode plates |
| JP2020510980A (en) * | 2017-11-09 | 2020-04-09 | エルジー・ケム・リミテッド | Strip type electrode used for cylindrical jelly roll and lithium secondary battery including the same |
| US11682765B2 (en) | 2019-03-29 | 2023-06-20 | Dongguan Poweramp Technology Limited | Electrode and electrochemical device including the same |
| US11728474B2 (en) | 2019-03-29 | 2023-08-15 | Dongguan Poweramp Technology Limited | Electrode and electrochemical device including the same |
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2011
- 2011-08-29 JP JP2011185503A patent/JP2014211944A/en not_active Withdrawn
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| WO2016121734A1 (en) * | 2015-01-30 | 2016-08-04 | Ｎｅｃエナジーデバイス株式会社 | Secondary battery |
| US10217988B2 (en) | 2015-01-30 | 2019-02-26 | Nec Energy Devices, Ltd. | Secondary battery |
| JP2017157515A (en) * | 2016-03-04 | 2017-09-07 | 株式会社Ｇｓユアサ | Power storage element |
| JP2020510980A (en) * | 2017-11-09 | 2020-04-09 | エルジー・ケム・リミテッド | Strip type electrode used for cylindrical jelly roll and lithium secondary battery including the same |
| JP7041811B2 (en) | 2017-11-09 | 2022-03-25 | エルジー エナジー ソリューション リミテッド | Strip type electrodes used for cylindrical jelly rolls and lithium secondary batteries containing them |
| US11637274B2 (en) | 2017-11-09 | 2023-04-25 | Lg Energy Solution, Ltd. | Strip-shaped electrode used for cylindrical jelly roll and lithium secondary battery comprising same |
| CN109841794A (en) * | 2019-03-29 | 2019-06-04 | 宁德新能源科技有限公司 | Electrode plates and electrochemical appliance comprising the electrode plates |
| US11682765B2 (en) | 2019-03-29 | 2023-06-20 | Dongguan Poweramp Technology Limited | Electrode and electrochemical device including the same |
| US11728474B2 (en) | 2019-03-29 | 2023-08-15 | Dongguan Poweramp Technology Limited | Electrode and electrochemical device including the same |
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