JP2011048912A - Lithium ion secondary battery electrode, and coater for electrode mixture - Google Patents
Lithium ion secondary battery electrode, and coater for electrode mixture Download PDFInfo
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- 239000000203 mixture Substances 0.000 title claims abstract description 139
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 25
- 238000001035 drying Methods 0.000 claims abstract description 127
- 238000000576 coating method Methods 0.000 claims abstract description 64
- 239000011888 foil Substances 0.000 claims abstract description 62
- 239000011248 coating agent Substances 0.000 claims abstract description 61
- 229910052751 metal Inorganic materials 0.000 claims abstract description 61
- 239000002184 metal Substances 0.000 claims abstract description 61
- 238000004804 winding Methods 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 22
- 238000005192 partition Methods 0.000 claims description 19
- 239000002131 composite material Substances 0.000 claims description 13
- 230000006698 induction Effects 0.000 claims description 10
- 238000007602 hot air drying Methods 0.000 claims description 8
- 238000007664 blowing Methods 0.000 claims description 4
- 230000000052 comparative effect Effects 0.000 description 20
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 8
- 239000011889 copper foil Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000011149 active material Substances 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 6
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000002390 adhesive tape Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000000748 compression moulding Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 239000002482 conductive additive Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000005001 laminate film Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
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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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
本発明は、リチウムイオン二次電池電極と、電極合材塗工機に関するものである。 The present invention relates to a lithium ion secondary battery electrode and an electrode mixture coating machine.
正極にリチウム含有複合酸化物を用い、負極に炭素材料、ケイ素材料等を用いるリチウムイオン二次電池は、高いエネルギー密度を実現できることから携帯電話、ノートパソコン用等の電源として、さらには、高い入出力特性を実現できることからハイブリッド自動車用の、あるいは電気自動車用の電源として使用されている。 Lithium-ion secondary batteries that use lithium-containing composite oxides for the positive electrode and carbon materials, silicon materials, etc. for the negative electrode can achieve high energy density, so they can be used as power sources for mobile phones and laptop computers. Since it can realize output characteristics, it is used as a power source for hybrid vehicles or electric vehicles.
特に金属箔、例えばアルミニウム箔を中間の１層に持つ樹脂フィルム主体の多層ラミネートフィルムを外装体として用いたラミネートフィルム外装型リチウムイオン二次電池は軽量である、放熱性に優れる、及び形状自由度が高い等の理由から注目が高まっている。 In particular, a laminated film exterior type lithium ion secondary battery using a multilayer laminate film mainly composed of a resin film having a metal foil, for example, an aluminum foil as an intermediate layer as an exterior body is light in weight, excellent in heat dissipation, and flexibility in shape. Attention is increasing for reasons such as high.
リチウムイオン二次電池では、一般に正極活物質材料、または負極活物質材料、及びバインダ、及び／または、導電助剤よりなる電極合材を混練し、集電体となる金属箔上に塗工、乾燥した後に、圧縮成形を行い、金属箔上に電極合材層を形成したものが電極として用いられている。バインダは、活物質粒子同士、活物質粒子と導電助剤粒子、または電極合材層と金属箔を結着させる働きがある。電極は、リチウムイオン電池の仕様（蓄電容量、寸法等）に応じて厚みや寸法などの条件が決定されて製造されている。 In a lithium ion secondary battery, a positive electrode active material or a negative electrode active material, and an electrode mixture made of a binder and / or a conductive additive are generally kneaded and applied onto a metal foil serving as a current collector. After drying, compression molding is performed, and an electrode mixture layer formed on a metal foil is used as an electrode. The binder functions to bind the active material particles, the active material particles and the conductive auxiliary particles, or the electrode mixture layer and the metal foil. The electrodes are manufactured with conditions such as thickness and dimensions determined according to the specifications (storage capacity, dimensions, etc.) of the lithium ion battery.
金属箔に電極合材を塗工して電極合材層を形成したら、乾燥する必要があるが、適切な条件で乾燥しないと、電極合材層の密着力が低くなる恐れがある。 If an electrode mixture layer is formed on a metal foil to form an electrode mixture layer, it needs to be dried. If the electrode mixture layer is not dried under appropriate conditions, the adhesion of the electrode mixture layer may be reduced.
この密着性に関して、特許文献１では、活物質層用塗工組成物の塗膜の乾燥を、集電体に対する密着性を低下させずに短時間で完了させることができる電極板の製造方法を提供すると共に、該製造方法を適用して製造された、活物質層の密着性が良好な電極板を提供することが記載されている。
Regarding this adhesion,
塗工後乾燥した電極が、すぐに圧縮成形されない場合、一旦、巻き取りコアに巻き取られる。その際、塗工乾燥後の電極合材層の厚みが幅方向端部で盛り上がっていると、巻き取りコアに連続して巻き取られることで厚みが蓄積され、巻き取った電極の幅方向端部で大きな盛り上がりが発生する。この盛り上がりにより、電極の伸び、タルミが生じ、さらには、亀裂、破断する恐れがある。 When the electrode dried after coating is not immediately compression-molded, it is once wound around the winding core. At that time, if the thickness of the electrode mixture layer after coating and drying is raised at the end in the width direction, the thickness is accumulated by being continuously wound on the winding core, and the width direction end of the wound electrode Large excitement occurs in the part. Due to this swell, there is a possibility that the electrode is stretched and talmi, and further cracked and broken.
盛り上がり対策として、塗工乾燥後の巻き取り電極の幅方向端部の盛り上がりが生じる前に電極の巻き取りを完了して、新たな巻き取りコアに巻き始めることで、電極の伸び、タルミ、亀裂、破断の発生を防いでいる。電極合材層の盛り上がりを防止できれば、電極の伸び、タルミ、亀裂、破断の発生を抑えて、巻き取り長さの長尺化が可能となる。巻き取り電極の切り換え回数を削減して、連続運転時間を長くできれば、生産性を向上することができる。 As countermeasures against swell, complete the winding of the electrode before the end of the winding electrode in the width direction after coating drying occurs, and start winding on a new winding core. This prevents the occurrence of breakage. If the swell of the electrode mixture layer can be prevented, the winding length can be increased by suppressing the occurrence of electrode elongation, talmi, cracks, and breakage. Productivity can be improved if the number of times of switching the winding electrode can be reduced and the continuous operation time can be increased.
図８は、リチウムイオン二次電池電極の従来の電極合材塗工機の正面図である。 FIG. 8 is a front view of a conventional electrode mixture coating machine for lithium ion secondary battery electrodes.
従来のリチウムイオン二次電池の電極合材塗工方法について図８を用いて説明する。金属箔１は金属箔巻き出し部１１から送り出され、塗工装置２より、金属箔１上面に電極合材が塗工され、乾燥装置３を通って乾燥され、電極巻き取り部２１に巻き取られる。ここでは乾燥装置３が、第１乾燥ゾーン１３、第２乾燥ゾーン２３、第３乾燥ゾーン３３から構成されているが、乾燥装置３の長さ等の要因により３つの乾燥ゾーンに限定されるものではない。
A conventional electrode mixture coating method for a lithium ion secondary battery will be described with reference to FIG. The
第１乾燥ゾーン１３では、温風装置４は金属箔１の電極合材層塗工面の下面側のみから温風を送り電極合材層へ温風が直接あたらない加熱を行っている。第２乾燥ゾーン２３、第３乾燥ゾーン３３は、電極合材層塗工面の上面側および下面側の双方に温風装置４が配置されており、上下方向から電極合材層を乾燥している。乾燥した電極は、電極巻き取り部２１に連続的に巻き取られる。
In the
第１乾燥ゾーン内において、電極合材層塗工面の下面側から金属箔全体へ温風が均等に吹き付けられるようにノズルが設定されている場合には、幅方向の塗工されない金属箔部へも均等に温風が吹き付けられる。したがって、塗工面において電極合材が塗工されていない金属箔に接する電極合材層の幅方向の端部近傍の電極合材の温度が上がりやすい。また温風の回り込みが発生すれば、塗工表面からも乾燥されることになる。 In the first drying zone, when the nozzle is set so that hot air is uniformly blown from the lower surface side of the electrode mixture layer coating surface to the entire metal foil, to the metal foil portion not coated in the width direction Even warm air is sprayed. Therefore, the temperature of the electrode mixture in the vicinity of the end in the width direction of the electrode mixture layer in contact with the metal foil to which the electrode mixture is not applied on the coated surface is likely to rise. In addition, if hot air wraps around, the coating surface is also dried.
図４は、リチウムイオン二次電池電極の従来の電極合材塗工方法による幅方向の模式断面図である。 FIG. 4 is a schematic cross-sectional view in the width direction according to a conventional electrode mixture coating method for a lithium ion secondary battery electrode.
金属箔１の上に電極合材が塗工され、電極合材層４０が形成されている。電極合材層の幅方向端部近傍には、電極合材層の盛り上がり部４１が形成されている。
An electrode mixture is coated on the
図８に示している電極合材塗工機で電極合材を塗工した場合の断面は、図４のように電極合材層の盛り上がり部が形成される恐れがある。 In the cross section when the electrode mixture is applied by the electrode mixture application machine shown in FIG. 8, there is a possibility that the raised portion of the electrode mixture layer is formed as shown in FIG.
すなわち、従来の電極合材塗工方法では、電極全体を均一に加熱するために、乾燥後の電極合材層の幅方向端部近傍が、中央部より厚く盛り上がる恐れがある。 That is, in the conventional electrode mixture coating method, in order to uniformly heat the entire electrode, the vicinity of the end in the width direction of the dried electrode mixture layer may be thicker than the center.
温風乾燥により電極合材層が、幅方向端部近傍で厚くなりやすい理由は以下のとおりである。電極合材が押し出されて金属箔に塗工されると、金属箔上に広がっていくが、電極合材はスラリ状で粘度が高いので、電極合材の外周部は広がらないような力が働く。一方電極合材が押し出される中央部は、押し出されることにより電極合材を広げようとする力が働く。 The reason why the electrode mixture layer tends to be thick in the vicinity of the end in the width direction by hot air drying is as follows. When the electrode mixture is extruded and applied to the metal foil, it spreads on the metal foil, but the electrode mixture is a slurry and has a high viscosity, so that the outer periphery of the electrode mixture does not spread. work. On the other hand, in the central part where the electrode mixture is extruded, a force is applied to expand the electrode mixture by being pushed out.
結果として、塗工直後は、外周近傍の電極合材が盛り上がることになる。乾燥までに十分な時間があれば、粘度が高くても電極合材の厚みは均等になるが、すぐに電極は乾燥装置に送られるので、電極合材層は外周近傍が厚いままである。 As a result, immediately after coating, the electrode mixture in the vicinity of the outer periphery rises. If there is sufficient time to dry, the thickness of the electrode mixture becomes uniform even if the viscosity is high, but since the electrode is immediately sent to the drying device, the vicinity of the outer periphery of the electrode mixture layer remains thick.
乾燥装置内において、電極合材が塗工されていない未塗工部は、金属箔のみのため塗工部より暖まりやすい。そのため、電極合材層の幅方向端部近傍は、未塗工部と接しているため、電極合材層の中央部に比べて暖まりやすい。そのため、電極合材層の幅方向端部近傍は、溶媒が蒸発しやすく、電極合材層が乾燥しやすい。 In the drying apparatus, the uncoated part where the electrode mixture is not coated is easily heated than the coated part because of the metal foil alone. For this reason, the vicinity of the end portion in the width direction of the electrode mixture layer is in contact with the uncoated portion, so that it is easier to warm than the center portion of the electrode mixture layer. Therefore, in the vicinity of the end portion in the width direction of the electrode mixture layer, the solvent is easily evaporated and the electrode mixture layer is easily dried.
乾燥過程における電極合材の平滑化速度より、溶剤の乾燥する速度（蒸発速度）が速いと、電極合材層の盛り上がりが解消される前に、電極合材の流動性が失われるので、電極合材層の幅方向端部近傍が盛り上がった電極が得られる。 If the solvent drying rate (evaporation rate) is faster than the electrode mixture smoothing speed during the drying process, the fluidity of the electrode mixture is lost before the swell of the electrode mixture layer is eliminated. An electrode in which the vicinity of the end portion in the width direction of the composite layer is raised is obtained.
上記のように、金属箔上に電極合材が押し出され、塗工した際に生じた厚みのバラツキが解消される前に、電極合材層の幅方向端部近傍から乾燥することにより、幅方向端部近傍が中央部より厚い電極となる。また、場所によって乾燥スピードが違うと、バインダ分布が不均一となり、金属箔と活物質との結着力に影響を与える。結着力の低下は電極合材層の剥離の原因の一つとなる。 As described above, the electrode mixture is extruded onto the metal foil, and before the variation in thickness generated when coating is eliminated, the electrode mixture layer is dried from the vicinity of the end in the width direction of the electrode mixture layer. The vicinity of the direction end becomes an electrode thicker than the center. In addition, if the drying speed varies depending on the location, the binder distribution becomes non-uniform, which affects the binding force between the metal foil and the active material. The decrease in the binding force is one of the causes of peeling of the electrode mixture layer.
電極合材層の幅方向端部近傍の盛り上がりは、電極の巻き取り時において、盛り上がり同士が重なることになる。巻き取り後の電極の幅方向端部と中央部に厚みの差が生じ、これが連続して重なることにより、その差が大きくなり、電極合材層の幅方向端部が引き伸ばされ、巻きの周長に違いが生じ、タルミが発生し易くなる。さらには、金属箔の伸びが追随できなくなると亀裂が入り、破断する恐れがある。 The bulge in the vicinity of the end portion in the width direction of the electrode mixture layer is overlapped when the electrode is wound. A difference in thickness occurs between the widthwise end and the center of the electrode after winding, and this overlaps continuously, increasing the difference, and stretching the widthwise end of the electrode composite layer, There is a difference in length, which tends to cause tarmi. Furthermore, if the elongation of the metal foil cannot follow, there is a risk of cracking and breaking.
これに対して、さまざまな知見が得られており、現行の対策法としては、乾燥装置に入る前に、盛り上がりになる部分の電極合材をエア吹付けにより塗り広げることや、乾燥後に、電極合材層の盛り上がり部分を加圧ローラーで圧縮することなどが行われている。しかし前者は、過剰にエアを吹付けることにより電極合材層の厚みを薄くする恐れがあり、後者は、盛り上がり部以外の電極合材層を過剰に圧縮する恐れがある。 On the other hand, various knowledge has been obtained, and the current countermeasure method is to spread the electrode mixture of the swelled part by air blowing before entering the drying device, or after drying, the electrode For example, the rising portion of the composite layer is compressed with a pressure roller. However, the former may reduce the thickness of the electrode mixture layer by excessively blowing air, and the latter may excessively compress the electrode mixture layer other than the raised portion.
また、金属箔や電極合材層の塗工幅が狭い場合には、電極合材を塗工する下面側からの温風が上面側に回り込み、回り込む温風により幅方向端部近傍の乾燥がより促進され、盛り上がりが解消され難くなる恐れがある。 In addition, when the coating width of the metal foil or electrode mixture layer is narrow, the warm air from the lower surface side where the electrode mixture is applied wraps around the upper surface side, and the hot air flowing around causes drying in the vicinity of the end in the width direction. There is a risk that it will be more promoted and it will be difficult to eliminate the excitement.
電極合材層の幅方向端部から、塗工幅の約１０％までの位置、特に、塗工幅の約３％までの位置の乾燥速度が早く、盛り上がりが発生しやすいことが、さまざまな知見から得られている。 There are various cases in which the drying speed is high at positions up to about 10% of the coating width from the end in the width direction of the electrode mixture layer, particularly up to about 3% of the coating width, and swell is likely to occur. Obtained from knowledge.
図５は、電極合材層の幅方向端部近傍の盛り上がりのある電極を巻き取った状態を示す模式図である。 FIG. 5 is a schematic diagram showing a state in which a swelled electrode in the vicinity of the end portion in the width direction of the electrode mixture layer is wound up.
電極合材層５１の幅方向端部近傍が盛り上がった電極を巻き取りコア５３に巻き取ると、盛り上がり部分が累積されて、盛り上がり部５４ができる。
When the electrode in which the vicinity of the end portion in the width direction of the
図６は、図５の電極をさらに巻き続けた状態を示す模式図である。 FIG. 6 is a schematic view showing a state in which the electrode of FIG. 5 is further wound.
図５の電極をさらに巻き続けると、盛り上がり部５４がさらに累積されて、亀裂発生部５５が現れる恐れがある。
If the electrode of FIG. 5 is further wound, the swelled
電極合材層の幅方向端部近傍の盛り上がりは、１０μｍ程度の盛り上がり同士が重なると、図５のように巻き取り後の電極合材層の幅方向端部に数ｍｍ程度の盛り上がりを発生させることになる。これが電極合材層の幅方向端部近傍の伸びの原因になり、タルミが発生することになる。さらに巻き取り続けた場合には、図６のように盛り上がり部分の伸びに金属箔が追随できなくなり電極に亀裂が入り破断する恐れがある。そのため、電極巻き取り長さを長くすることが制限される。電極合材層の幅方向端部近傍の盛り上がりの低減ができれば、電極巻き取りの長尺化ができ、生産性向上に寄与できる。 As for the bulges in the vicinity of the end portions in the width direction of the electrode mixture layer, when the bulges of about 10 μm overlap each other, a bulge of about several mm is generated at the end portions in the width direction of the electrode mixture layer after winding as shown in FIG. It will be. This causes elongation in the vicinity of the end portion in the width direction of the electrode composite material layer, and tarmi is generated. Further, if the winding is continued, the metal foil cannot follow the stretch of the raised portion as shown in FIG. 6, and the electrode may crack and break. Therefore, it is limited to increase the electrode winding length. If the rise in the vicinity of the end portion in the width direction of the electrode mixture layer can be reduced, the electrode winding can be lengthened, which can contribute to the improvement of productivity.
本発明は、上記の課題を解決するものであり、乾燥後の電極において、電極合材層の幅方向端部近傍においても、中央部と同じ厚みの電極を作製し、乾燥後の電極の巻き取りの長尺化を可能とするリチウムイオン二次電池電極の提供を目的とする。 The present invention solves the above-mentioned problems, and in the dried electrode, an electrode having the same thickness as that of the central portion is produced in the vicinity of the end portion in the width direction of the electrode mixture layer, and the electrode is wound after drying. An object of the present invention is to provide a lithium ion secondary battery electrode that can be made longer.
すなわち、本発明の技術的課題は、電極合材層の幅方向の厚みをほぼ均一にし、乾燥後の電極の巻き取りの長尺化を可能とするリチウムイオン二次電池電極と、電極合材塗工機を提供することにある。 That is, the technical problem of the present invention is to provide a lithium ion secondary battery electrode that makes the thickness of the electrode mixture layer substantially uniform in the width direction and makes it possible to lengthen the winding of the electrode after drying, and the electrode mixture To provide a coating machine.
本発明のリチウムイオン二次電池電極は、金属箔に電極合材を塗工し、乾燥装置で乾燥して作製するリチウムイオン二次電池電極であって、電極合材層の幅方向の両端部近傍における厚みが、中央部の９５％以上、１０５％以下であることを特徴とする。 The lithium ion secondary battery electrode of the present invention is a lithium ion secondary battery electrode produced by applying an electrode mixture on a metal foil and drying it with a drying device, both ends of the electrode mixture layer in the width direction. The thickness in the vicinity is 95% or more and 105% or less of the central portion.
本発明のリチウムイオン二次電池電極は、前記両端部近傍は、前記電極合材層の塗工端から、塗工幅の１０％に相当する幅であることを特徴とする。 The lithium ion secondary battery electrode of the present invention is characterized in that the vicinity of both ends is a width corresponding to 10% of the coating width from the coating end of the electrode mixture layer.
本発明の電極合材塗工機は、金属箔巻き出し部、塗工装置、乾燥装置および電極巻き取り部を備え、金属箔に電極合材を塗工し、乾燥装置で乾燥する電極合材塗工機であって、前記塗工装置では、前記電極合材を一定量貯蔵するダムから弁の開閉動作によって塗工を行って電極合材層を形成し、前記乾燥装置では、複数の乾燥ゾーンを有し、第１乾燥ゾーンは前記金属箔の下面側から、第２乾燥ゾーン以降は上面側と下面側から乾燥熱源を供給し、前記乾燥は、熱風加熱方式、誘導加熱方式もしくは赤外加熱方式のうちの一つまたはそれらの組み合わせで前記電極合材層の乾燥を行うことを特徴とする。 The electrode mixture coating machine of the present invention comprises a metal foil unwinding section, a coating apparatus, a drying apparatus, and an electrode winding section, and the electrode mixture is applied to the metal foil and dried by the drying apparatus. In the coating apparatus, in the coating apparatus, an electrode mixture layer is formed by applying an open / close operation of a valve from a dam that stores a certain amount of the electrode mixture, and the drying apparatus performs a plurality of drying operations. The first drying zone supplies a drying heat source from the lower surface side of the metal foil, and the second and subsequent drying zones from the upper surface side and the lower surface side, and the drying is performed by a hot air heating method, induction heating method or infrared. The electrode mixture layer is dried by one or a combination of heating methods.
本発明の電極合材塗工機は、前記熱風乾燥方式において、前記第１乾燥ゾーンには、前記下面側に前記電極合材層の幅方向の８０％以上、１００％以下の範囲で、前記金属箔の中心線に対して左右対称に温風が吹き付けられる衝立板を備え、前記衝立板の内側から温風を吹き出すことを特徴とする。 The electrode mixture coating machine of the present invention is the hot air drying method, wherein the first drying zone has a range of 80% or more and 100% or less in the width direction of the electrode mixture layer on the lower surface side. There is provided a partition plate to which hot air is blown symmetrically with respect to the center line of the metal foil, and the hot air is blown out from the inside of the partition plate.
本発明により、電極合材層の幅方向の厚みをほぼ均一にし、乾燥後の電極の巻き取りの長尺化を可能とするリチウムイオン二次電池電極と電極合材塗工機の提供が可能となる。 According to the present invention, it is possible to provide a lithium ion secondary battery electrode and an electrode mixture coating machine that make the electrode mixture layer substantially uniform in the width direction and can lengthen the winding of the electrode after drying. It becomes.
本発明の実施の形態を説明する。 An embodiment of the present invention will be described.
電極合材が金属箔に押し出される際、粘度が高いために中央部より端部が厚くなり、平滑化される前に乾燥されるので幅方向端部近傍が盛り上がった電極となる。 When the electrode mixture is extruded onto the metal foil, the end is thicker than the center due to its high viscosity and is dried before being smoothed, so that the vicinity of the end in the width direction is raised.
本発明では、端部の乾燥、すなわち電極合材の固定化を遅らせることによって電極合材層の盛り上がりを解消し、幅方向の厚みをほぼ均一にすることで、乾燥後の電極の巻き取りの長尺化を可能とするリチウムイオン二次電池電極と、電極合材塗工機を提供するものである。 In the present invention, the end portion of the electrode mixture layer is eliminated by delaying the drying of the electrode mixture, that is, the electrode mixture is fixed, and the thickness in the width direction is made substantially uniform, so that the electrode can be wound up after drying. The present invention provides a lithium ion secondary battery electrode and an electrode mixture coating machine that can be lengthened.
図１は、本発明の電極合材塗工機の正面図である。 FIG. 1 is a front view of an electrode mixture coating machine according to the present invention.
金属箔巻き出し部１１から金属箔１を巻き出して、塗工装置２で金属箔１上に電極合材を塗工する。塗工された金属箔１は、第１乾燥ゾーン１３、第２乾燥ゾーン２３、第３乾燥ゾーン３３を備える乾燥装置３に送られる。
The
第１乾燥ゾーン１３では、塗工面とは逆の下面側に配置された温風装置４から温風が吹き出されるが、衝立板５により、吹き出される温風の範囲が制限される。第２乾燥ゾーン２３、第３乾燥ゾーン３３では、衝立板などの制限なく上面側と下面側から、温風が吹き出される。乾燥が完了して、電極は電極巻き取り部２１に巻き取られる。
In the
乾燥装置の大きさや乾燥ゾーン数等は、金属箔の搬送速度、電極合材の塗工量、温風の温度、風量などによって適切に設計されるべきものである。 The size of the drying device, the number of drying zones, and the like should be appropriately designed according to the conveying speed of the metal foil, the coating amount of the electrode mixture, the temperature of the hot air, the air volume, and the like.
図１では、乾燥装置は、第１乾燥ゾーン、第２乾燥ゾーン、第３乾燥ゾーンの３つのゾーンで示した。金属箔の下面側に温風装置を設けた第１乾燥ゾーンを少なくとも１箇所設けることは必要であるが、金属箔の上面側と下面側の双方に温風装置を設けた乾燥ゾーンは、図１に限定されず１箇所以上あればよい。また、図１では、熱風乾燥方式を示したが、誘導加熱（ＩＨ）、赤外加熱、そのほかの加熱方式であってもよい。 In FIG. 1, the drying apparatus is shown by three zones, a first drying zone, a second drying zone, and a third drying zone. Although it is necessary to provide at least one first drying zone provided with a hot air device on the lower surface side of the metal foil, the drying zone provided with the hot air device on both the upper surface side and the lower surface side of the metal foil is illustrated in FIG. The number is not limited to 1, and there may be one or more locations. Moreover, although the hot air drying system was shown in FIG. 1, induction heating (IH), infrared heating, and other heating systems may be used.
図２は、本発明の電極合材塗工機の第１乾燥ゾーンの側面図である。 FIG. 2 is a side view of the first drying zone of the electrode composite material coating machine of the present invention.
温風は、塗工面とは逆の下面側に配置された温風装置４から吹き出され、金属箔１上の電極合材層４０を乾燥する。温風が電極合材層４０の幅方向端部近傍に吹き出さないように衝立板５を設置している。
The warm air is blown out from the
温風を上面側から吹き付けると、電極合材層の表面が急激に乾燥され、幅方向端部近傍の盛り上がりを解消できなくなるため、下面側からの吹き付けであるのが好ましい。 When hot air is blown from the upper surface side, the surface of the electrode mixture layer is dried rapidly, and the bulge in the vicinity of the end in the width direction cannot be eliminated. Therefore, it is preferable to blow from the lower surface side.
衝立板は、電極合材層の幅の８０％以上、１００％以下の範囲に、中心線に対して左右対称に、温風が当たるように移動できるのが好ましい。衝立板は、電極合材層の幅の３％以下の幅だけ電極合材層の内側（電極合材層の幅の９４％以上、１００％以下の範囲）にあるのが、特に好ましい。 It is preferable that the partition plate can move in a range of 80% or more and 100% or less of the width of the electrode mixture layer so as to be struck by hot air symmetrically with respect to the center line. It is particularly preferable that the partition plate is inside the electrode mixture layer (a range of 94% or more and 100% or less of the width of the electrode mixture layer) by a width of 3% or less of the width of the electrode mixture layer.
左右対称でないと端部近傍の乾燥にむらができてしまい、乾燥が不十分になる恐れがあるからである。乾燥が不十分だと、電極巻き取り時に電極合材がローラーに付着したり、次の工程である電極を規定の厚さに圧縮する電極圧縮工程で圧縮ロールへ転写したりする恐れがある。また、温風の当たる範囲が８０％未満だと乾燥が不十分、１００％を超えると乾燥が速すぎて端部近傍の盛り上がりを解消できない恐れがある。 This is because if it is not symmetric, unevenness in the vicinity of the end portion may occur and drying may be insufficient. If the drying is insufficient, the electrode mixture may adhere to the roller during winding of the electrode, or may be transferred to a compression roll in an electrode compression step in which the electrode, which is the next step, is compressed to a specified thickness. Further, if the range where the hot air hits is less than 80%, the drying is insufficient, and if it exceeds 100%, the drying is too fast and the swell in the vicinity of the end may not be eliminated.
さらに、電極塗工幅が変化した場合でも、電極合材層の塗工幅に応じて、衝立板の位置を変化させることで同様の効果を得ることができる。 Furthermore, even when the electrode coating width is changed, the same effect can be obtained by changing the position of the partition plate according to the coating width of the electrode mixture layer.
衝立板により、電極合材層の幅に対して左右対称に０以上、１０％以下の端部近傍に温風を吹き出さないようにしている。温風を吹き出さない部分は、直接加熱することなく金属箔等からの余熱で乾燥させている。 The screen prevents the hot air from being blown out in the vicinity of the end of 0 to 10% symmetrically with respect to the width of the electrode mixture layer. The portion where the warm air is not blown out is dried by the residual heat from the metal foil or the like without being directly heated.
衝立板は、垂直に設置するのが好ましく、温風を遮ることができ、温風の温度でも変形等しなければ材質は問わない。２００℃に耐えられる材質であるのが好ましい。また、金属箔までの高さ方向の間隙は、可能な限り狭いのが好ましい。金属箔の搬送に影響を与えてはならない。 The partition plate is preferably installed vertically, can block hot air, and may be made of any material as long as it does not deform even at the temperature of the hot air. A material that can withstand 200 ° C. is preferable. Further, the gap in the height direction to the metal foil is preferably as narrow as possible. It must not affect the transport of the metal foil.
衝立板により、電極合材層の幅方向端部近傍が、中央部より早く乾燥することを防いでいる。また、温風が塗工面へ回り込みにくくなっているので、電極合材層の表面が急激に乾燥するのを防いでいる。 The partition plate prevents the vicinity of the end portion in the width direction of the electrode mixture layer from drying faster than the central portion. Moreover, since the warm air is less likely to wrap around the coating surface, the surface of the electrode mixture layer is prevented from drying out rapidly.
第１乾燥ゾーンが誘導加熱（ＩＨ）、赤外加熱方式の場合には、被加熱部分のみを加熱することができるため、塗工端部での処置が重要となる。ヒーターの幅は、ヒーターによる加熱範囲にあわせた設計が必要となる。加熱範囲を電極合材層幅より広くした場合には、塗工端部が局部的に高温になり急激に乾燥するので、盛り上がり、電極剥離強度の低下を引き起こす恐れがある。 When the first drying zone is induction heating (IH) or infrared heating, only the heated portion can be heated, so that treatment at the coating end is important. The width of the heater needs to be designed according to the heating range of the heater. When the heating range is made wider than the electrode mixture layer width, the coating end portion becomes locally high in temperature and dries rapidly, so that it may rise and cause a decrease in electrode peeling strength.
ヒーターの幅は、電極合材層幅の８０％以上、１００％以下の範囲であって、中心線に対して左右対称であるのが好ましい。左右対称でないと、端部近傍の乾燥にむらができてしまい、乾燥が不十分になる恐れがあるからである。また、ヒーターの幅が８０％未満だと乾燥が不十分、１００％を超えると乾燥が速すぎて端部近傍の盛り上がりを解消できない恐れがあるからである。被加熱部分のみを加熱できるので、衝立板は不要である。 The width of the heater is preferably in the range of 80% or more and 100% or less of the electrode mixture layer width, and is preferably symmetrical with respect to the center line. This is because if it is not symmetric, unevenness in the vicinity of the end portion may occur and drying may be insufficient. Further, if the heater width is less than 80%, the drying is insufficient, and if it exceeds 100%, the drying is too fast and the bulge in the vicinity of the end may not be eliminated. Since only the part to be heated can be heated, a partition plate is unnecessary.
第２乾燥ゾーン以降には、衝立板がなく、上面側および下面側から温風が吹き出しており、全体を均等に乾燥する構造になっている。すなわち、第１乾燥ゾーンで、電極合材と金属箔の、幅方向の温度を均一にすることが求められるとともに、電極合材の盛り上がりを解消しておく必要がある。 After the second drying zone, there is no screen, warm air is blown out from the upper surface side and the lower surface side, and the whole is uniformly dried. That is, it is required to make the temperature in the width direction of the electrode mixture and the metal foil uniform in the first drying zone, and it is necessary to eliminate the swell of the electrode mixture.
このため、第１乾燥ゾーンでは温度が上がりにくい電極合材の温度を高くする必要があり、電極合材を塗工しない金属箔近傍は温度が上がり過ぎないように温風の吹き付けを制限する必要がある。 For this reason, it is necessary to increase the temperature of the electrode mixture that is difficult to rise in the first drying zone, and it is necessary to limit the blowing of warm air in the vicinity of the metal foil that is not coated with the electrode mixture so that the temperature does not rise excessively. There is.
また、第１乾燥ゾーンでの乾燥スピードの違いは、バインダ分布が不均一となり、金属箔と活物質との結着力に影響を与えるが、均一なスピードで乾燥することにより電極合材層と金属箔との密着強度を向上することができる。 In addition, the difference in drying speed in the first drying zone makes the binder distribution non-uniform and affects the binding force between the metal foil and the active material. By drying at a uniform speed, the electrode mixture layer and metal The adhesion strength with the foil can be improved.
第１乾燥ゾーンに関して、従来の、全体を均一に加熱する方式に比べて、本発明の加熱方法は、必要となる部分だけを加熱しており、エネルギー使用量を低減しており、省エネ効果も有する。 Compared to the conventional method of uniformly heating the entire first drying zone, the heating method of the present invention heats only the necessary part, reduces the amount of energy used, and has an energy saving effect. Have.
以下に本発明の実施例を詳述する。 Examples of the present invention are described in detail below.
本発明のリチウムイオン二次電池電極に関して、アノード電極を製造した例について説明する。 The example which manufactured the anode electrode is demonstrated regarding the lithium ion secondary battery electrode of this invention.
（実施例１）
本発明の実施例として、金属箔には幅４２０ｍｍ、厚さ８μｍの銅箔を用いた。銅箔に塗工される電極合材には、固形分全量を１００質量％（以下ｗｔ％と記載）とした場合、活物質として人造黒鉛粉末を９６ｗｔ％、バインダとしてポリフッ化ビニリデン（ＰＶＤＦ）を３ｗｔ％、導電助剤としてカーボンブラックを１ｗｔ％使用した。溶剤はＮ−メチル−ピロリドン（ＮＭＰ）を用いた。これらの原料をホモジ方式ミキサにて撹拌して電極合材を作成した。電極合材の粘度は１２Ｐａ・ｓ（パスカル秒）であった。
Example 1
As an example of the present invention, a copper foil having a width of 420 mm and a thickness of 8 μm was used as the metal foil. In the electrode mixture coated on the copper foil, when the total solid content is 100% by mass (hereinafter referred to as wt%), the artificial graphite powder is 96 wt% as the active material, and the polyvinylidene fluoride (PVDF) is the binder. 3 wt%, and 1 wt% of carbon black was used as a conductive aid. N-methyl-pyrrolidone (NMP) was used as the solvent. These raw materials were stirred with a homogenizer mixer to prepare an electrode mixture. The viscosity of the electrode mixture was 12 Pa · s (Pascal second).
銅箔長さは、２００ｍであった。製品のピッチは４８３ｍｍであり、連続して４００セグメント以上の塗工、乾燥を行った。乾燥後の銅箔を除いた電極合材層の塗工量が９．５ｍｇ／ｃｍ２になるように塗工したところ、乾燥後の中央部分の厚さが１０２μｍとなった。銅箔を含めた中央部分の厚さは１１０μｍであった。 The copper foil length was 200 m. The product pitch was 483 mm, and 400 segments or more were continuously applied and dried. When the coating amount of the electrode mixture layer excluding the dried copper foil was 9.5 mg / cm 2 , the thickness of the central part after drying was 102 μm. The thickness of the central part including the copper foil was 110 μm.
電極合材の塗工、乾燥には、図１の塗工機（ヒラノテクシード社製）を使用した。各乾燥ゾーンの条件は、第１乾燥ゾーンの設定温度が１３０℃、銅箔面に垂直な方向の風速が５ｍ／ｓ、第２乾燥ゾーンの設定温度が１２０℃、風速が５ｍ／ｓ、第３乾燥ゾーンの設定温度が１３０℃、風速が１７ｍ／ｓ、と設定した。 For coating and drying of the electrode mixture, the coating machine shown in FIG. 1 (manufactured by Hirano Tech Seed) was used. The conditions of each drying zone are as follows: the set temperature of the first drying zone is 130 ° C., the wind speed in the direction perpendicular to the copper foil surface is 5 m / s, the set temperature of the second drying zone is 120 ° C., the wind speed is 5 m / s, The set temperature of the three drying zones was set to 130 ° C., and the wind speed was set to 17 m / s.
銅箔の幅方向両端から５ｍｍ内側の位置に、電極合材層の幅が４００ｍｍとなるように塗工した。第１乾燥ゾーンにて、下面側に間隔３９０ｍｍの衝立板を設置した。衝立板を設置して、電極に当たる風速が５ｍ／ｓとなるように調整した結果、ファンの回転数は、衝立板を設置する前の状態を１００とすると８５であった。これは、後述する比較例１のファン回転数を１００とした場合の回転数の比が８５であったことを意味する。以上の変更をした後にアノード電極を製造した。
Coating was performed at a
また、電極合材の塗工条件は、塗工速度、すなわち銅箔の送り速度を１．０ｍ／分とした。 Moreover, the coating conditions of electrode compound material made the coating speed, ie, the feeding speed of copper foil, 1.0m / min.
金属箔と電極合材層の結着力の評価のために、電極剥離強度を測定した。 In order to evaluate the binding force between the metal foil and the electrode mixture layer, the electrode peel strength was measured.
図７は、剥離強度測定方法の説明図で、図７（ａ）は電極試料を固定した状態を示す側面図、図７（ｂ）は金属箔を剥離した状態を示す側面図である。 7A and 7B are explanatory views of the peel strength measuring method. FIG. 7A is a side view showing a state where an electrode sample is fixed, and FIG. 7B is a side view showing a state where a metal foil is peeled off.
製造したアノード電極を１２ｍｍ幅の短冊状に切断して電極試料７０を作製し、試料固定板７４に両面粘着テープ７３にて固定した。金属箔７２を電極合材層７１から引き剥がし、下端を矢印方向である垂直上方に引き上げ、電極試料７０から金属箔７２を剥離した際の加重を引っ張り試験機にて計測し、電極剥離強度を求めた。
The manufactured anode electrode was cut into a strip shape having a width of 12 mm to produce an
（実施例２）
第１乾燥ゾーンにて、下面側に間隔３８０ｍｍの衝立板を設置し、比較例１のファン回転数を１００とした場合の回転数の比を８３とした以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Example 2)
In the first drying zone, an anode was installed in the same manner as in Example 1 except that a partition plate having a spacing of 380 mm was installed on the lower surface side, and the ratio of the rotational speed was 83 when the fan rotational speed of Comparative Example 1 was 100. An electrode was manufactured. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（実施例３）
第１乾燥ゾーンにて、下面側に間隔３６０ｍｍの衝立板を設置し、比較例１のファン回転数を１００とした場合の回転数の比を７８とした以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Example 3)
In the first drying zone, an anode plate was installed in the same manner as in Example 1 except that a partition plate having a spacing of 360 mm was installed on the lower surface side, and the rotation speed ratio was set to 78 when the fan rotation speed was 100 in Comparative Example 1. An electrode was manufactured. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（実施例４）
第１乾燥ゾーンにて、下面側に間隔３４０ｍｍの衝立板を設置し、比較例１のファン回転数を１００とした場合の回転数の比を７４とした以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
Example 4
In the first drying zone, an anode plate was installed in the same manner as in Example 1 except that a partition plate having a spacing of 340 mm was installed on the lower surface side and the ratio of the rotational speed was set to 74 when the fan rotational speed of Comparative Example 1 was 100. An electrode was manufactured. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（実施例５）
第１乾燥ゾーンにて、下面側に間隔３２０ｍｍの衝立板を設置し、比較例１のファン回転数を１００とした場合の回転数の比を６９とした以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Example 5)
In the first drying zone, an anode plate was installed in the same manner as in Example 1 except that a screen having a spacing of 320 mm was installed on the lower surface side, and the rotation speed ratio was 69 when the fan rotation speed was 100 in Comparative Example 1. An electrode was manufactured. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（実施例６）
第１乾燥ゾーンにて、下面側に間隔４００ｍｍの衝立板を設置し、比較例１のファン回転数を１００とした場合の回転数の比を８７とした以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Example 6)
In the first drying zone, an anode was installed in the same manner as in Example 1 except that a screen having a spacing of 400 mm was installed on the lower surface side, and the ratio of the rotational speed was set to 87 when the fan rotational speed was 100 in Comparative Example 1. An electrode was manufactured. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（比較例１）
第１乾燥ゾーンにて、衝立板を設置せず、ファン回転数の比を１００のままとして回転数を変えなかった以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Comparative Example 1)
In the first drying zone, an anode electrode was produced in the same manner as in Example 1 except that no screen was installed, the fan rotation speed ratio was kept at 100, and the rotation speed was not changed. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（比較例２）
第１乾燥ゾーンにて、下面側に間隔３００ｍｍの衝立板を設置し、比較例１のファン回転数を１００とした場合の回転数の比を６４とした以外は実施例１と同様にしてアノード電極を製造した。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Comparative Example 2)
In the first drying zone, an anode plate was installed in the same manner as in Example 1 except that a screen having a spacing of 300 mm was installed on the lower surface side, and the ratio of the rotational speed was 64 when the fan rotational speed was 100 in Comparative Example 1. An electrode was manufactured. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（実施例７）
第１乾燥ゾーンにて、衝立板を設置せず、第１乾燥ゾーンの乾燥方式に誘導加熱方式を採用して下面側に３８０ｍｍの誘導加熱コイルを中心線に対して左右対称に設置した以外は実施例１と同様にしてアノード電極を製造した。第１乾燥ゾーンにファンはない。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Example 7)
In the first drying zone, no screen is installed, the induction heating method is adopted as the drying method in the first drying zone, and the 380 mm induction heating coil is installed symmetrically with respect to the center line on the lower surface side. An anode electrode was produced in the same manner as in Example 1. There is no fan in the first drying zone. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（比較例３）
第１乾燥ゾーンにて、衝立板を設置せず、第１乾燥ゾーンの乾燥方式に誘導加熱方式を採用して下面側に４２０ｍｍの誘導加熱コイルを中心線に対して左右対称に設置した以外は実施例１と同様にしてアノード電極を製造した。第１乾燥ゾーンにファンはない。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Comparative Example 3)
In the first drying zone, no screen was installed, except that the induction heating method was adopted for the drying method of the first drying zone, and a 420 mm induction heating coil was installed symmetrically with respect to the center line on the lower surface side. An anode electrode was produced in the same manner as in Example 1. There is no fan in the first drying zone. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（実施例８）
第１乾燥ゾーンにて、衝立板を設置せず、第１乾燥ゾーンの乾燥方式に赤外加熱方式を採用して下面側に３８０ｍｍの赤外加熱ヒーターを中心線に対して左右対称に設置した以外は実施例１と同様にしてアノード電極を製造した。第１乾燥ゾーンにファンはない。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Example 8)
In the first drying zone, no screen was installed, and an infrared heating method was adopted as the drying method of the first drying zone, and an infrared heater of 380 mm was installed on the lower surface side symmetrically with respect to the center line. An anode electrode was produced in the same manner as Example 1 except for the above. There is no fan in the first drying zone. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
（比較例４）
第１乾燥ゾーンにて、衝立板を設置せず、第１乾燥ゾーンの乾燥方式に赤外加熱方式を採用して下面側に４２０ｍｍの赤外加熱ヒーターを中心線に対して左右対称に設置した以外は実施例１と同様にしてアノード電極を製造した。第１乾燥ゾーンにファンはない。アノード電極を１２ｍｍ幅に切断して電極剥離強度を測定した。
(Comparative Example 4)
In the first drying zone, no screen was installed, and the infrared heating method was adopted as the drying method of the first drying zone, and a 420 mm infrared heater was installed on the lower surface side symmetrically with respect to the center line. An anode electrode was produced in the same manner as Example 1 except for the above. There is no fan in the first drying zone. The anode electrode was cut to a width of 12 mm and the electrode peel strength was measured.
製作した電極について加熱方式、塗工端からの非加熱範囲、加熱範囲、ファン回転数の比、電極合材層厚さの差、電極剥離強度、電極ロール盛り上がり量および次の工程の電極圧縮成形での圧縮電極への転写発生有無を表１に示す。 About the manufactured electrode, heating method, non-heating range from coating end, heating range, fan rotation speed ratio, electrode mixture layer thickness difference, electrode peel strength, electrode roll swell amount and next step electrode compression molding Table 1 shows the presence or absence of transfer to the compression electrode.
（※２）電極合材層の幅方向端部から４０ｍｍ内側の部分の最大厚さと中央部分の厚さの差
（※３）電極合材層の幅方向端部から１０ｍｍ内側の部分の電極剥離強度
（※４）直径８１ｍｍの巻き取りコアに、２００ｍ分を連続製作したときの巻き取り電極での電極合材層の幅方向端部の電極ロール盛り上がり量
表１より、比較例２〜４において、圧縮電極への転写が発生しており、品質に不具合が発生した。 From Table 1, in Comparative Examples 2-4, the transfer to the compression electrode occurred, resulting in a defect in quality.
実施例１〜８の電極盛り上がり量は、比較例１より小さく、盛り上がり量に改善が見られた。同様に、電極ロール盛り上がり量も改善が見られた。 The electrode swell amount of Examples 1 to 8 was smaller than that of Comparative Example 1, and an improvement was seen in the swell amount. Similarly, the amount of swell of the electrode roll was also improved.
実施例１〜８のうち電極盛り上がり量が最も大きかった実施例６では、５μｍの電極盛り上がり量であり、電極中央部の電極合材層の厚さは１０２μｍで、幅方向端部近傍の電極合材層の厚さは１０７μｍであった。 In Example 6 in which the amount of electrode swell was the largest among Examples 1 to 8, the electrode swell amount was 5 μm, the thickness of the electrode mixture layer in the center of the electrode was 102 μm, and the electrode joint in the vicinity of the end in the width direction was The thickness of the material layer was 107 μm.
すなわち、実施例１〜８では、幅方向の両端部近傍における電極合材層の厚みが、中央部の１０４．９％（＝１０７／１０２）以下であることが確認できた。また、比較例１では、電極盛り上がり量が９μｍであったので、幅方向の両端部近傍における電極合材層の厚みが、中央部の１０８．８％（＝１１１／１０２）であった。つまり、幅方向の両端部近傍における電極合材層の厚みが、中央部の１０５％以下であれば電極ロール盛り上がり量は改善したと言える。 That is, in Examples 1 to 8, it was confirmed that the thickness of the electrode mixture layer in the vicinity of both end portions in the width direction was 104.9% (= 107/102) or less of the central portion. Further, in Comparative Example 1, since the electrode bulge amount was 9 μm, the thickness of the electrode mixture layer in the vicinity of both end portions in the width direction was 108.8% (= 111/102) of the central portion. That is, if the thickness of the electrode mixture layer in the vicinity of both end portions in the width direction is 105% or less of the central portion, it can be said that the amount of swelling of the electrode roll has improved.
電極剥離強度に関して、比較例１〜４よりも、実施例１〜８が高い値を示した。比較例１のように金属箔幅全体を加熱するように熱風乾燥すると、電極合材層の外側の金属箔が加熱されやすく、塗工端部が中央部に比べて乾燥しやすいのでバインダ分布が不均一となり、結果として金属箔と電極合材層との剥離強度が低かったものと考えられる。比較例３の誘導加熱方式や、比較例４の赤外加熱方式では、熱風乾燥より急激に乾燥されるため同様の現象を、より顕著に引き起こし、剥離強度は低かったものと考えられる。 Regarding the electrode peel strength, Examples 1 to 8 showed higher values than Comparative Examples 1 to 4. When hot air drying is performed so as to heat the entire width of the metal foil as in Comparative Example 1, the metal foil outside the electrode mixture layer is easily heated, and the coating end is easier to dry than the central portion, so the binder distribution is It is considered that the peel strength between the metal foil and the electrode mixture layer was low as a result. The induction heating method of Comparative Example 3 and the infrared heating method of Comparative Example 4 are considered to cause the same phenomenon more remarkably because they are dried more rapidly than hot air drying, and the peel strength is low.
これに対して、実施例１〜６の熱風乾燥方式の場合には衝立板を設置して塗工端部の急激な乾燥を抑制したので、剥離強度は高かったものと考えられる。実施例７の誘導加熱方式や実施例８の赤外加熱方式でも、衝立板は設置しないが、加熱範囲を制限したことで、同様に急激な乾燥を抑制できたので、剥離強度は高かったものと考えられる。 On the other hand, in the case of the hot air drying method of Examples 1 to 6, a partition plate was installed to suppress abrupt drying of the coating end, so that it was considered that the peel strength was high. Even in the induction heating method of Example 7 and the infrared heating method of Example 8, a screen was not installed, but by restricting the heating range, abrupt drying could be similarly suppressed, and the peel strength was high. it is conceivable that.
電極ロール盛り上がり量は、実施例１〜８が１ｍｍ以下であり、比較例１は２ｍｍであった。したがって本発明は、従来例より２倍以上多く巻くことができることがわかった。すなわち、幅方向の両端部近傍における電極合材層の厚みが、中央部の１０５％以下であれば、従来例より２倍以上多く巻くことができる。同様に、中央部の９５％以上であれば従来例より２倍以上多く巻くことができる。 The amount of swelling of the electrode roll was 1 mm or less in Examples 1 to 8, and 2 mm in Comparative Example 1. Therefore, it was found that the present invention can be wound more than twice as much as the conventional example. That is, when the thickness of the electrode mixture layer in the vicinity of both ends in the width direction is 105% or less of the central portion, it can be wound twice or more than the conventional example. Similarly, if it is 95% or more of the central portion, it can be wound more than twice as much as the conventional example.
塗工端部の急激な乾燥を抑制することで、電極合材層の幅方向の厚みをほぼ均一にし、剥離強度が高く、電極盛り上がり量が小さい電極を作製することができた。 By suppressing the rapid drying of the coating end, it was possible to make an electrode mixture layer having a substantially uniform thickness in the width direction, a high peel strength, and a small electrode bulge amount.
このことから、乾燥後の電極の巻き取りの長尺化を可能とするリチウムイオン二次電池電極と、電極合材塗工機の提供が可能であることが確認できた。 From this, it has been confirmed that it is possible to provide a lithium ion secondary battery electrode and an electrode mixture coating machine that can lengthen the winding of the electrode after drying.
以上、実施例を用いて、この発明の実施の形態を説明したが、この発明は、これらの実施例に限られるものではなく、この発明の要旨を逸脱しない範囲の設計変更があっても本発明に含まれる。すなわち、当業者であれば、当然なしえるであろう各種変形、修正もまた本発明に含まれる。 The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.
１ 金属箔
２ 塗工装置
３ 乾燥装置
４ 温風装置
５ 衝立板
１１ 金属箔巻き出し部
１３ 第１乾燥ゾーン
１４ 温風の流れ
２１ 電極巻き取り部
２３ 第２乾燥ゾーン
３３ 第３乾燥ゾーン
４０ 電極合材層
４１ 盛り上がり部
５１ 電極合材層
５２ 金属箔部
５３ 巻き取りコア
５４ 盛り上がり部
５５ 亀裂発生部
７０ 電極試料
７１ 電極合材層
７２ 金属箔
７３ 両面粘着テープ
７４ 試料固定板
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| KR101757517B1 (en) * | 2014-10-02 | 2017-07-12 | 주식회사 엘지화학 | Preparation method of cathode electrode and cathode electrode produced by the same |
| JP2020042899A (en) * | 2018-09-06 | 2020-03-19 | トヨタ自動車株式会社 | Electrode mixture layer |
| EP4043858A4 (en) * | 2020-06-23 | 2022-11-09 | LG Energy Solution, Ltd. | Fatigue testing apparatus for metallic foil and method using same |
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