JP3653913B2 - Sheet electrode and non-aqueous secondary battery using the same - Google Patents

Description

【００６２】
（正極シートの作製）
正極材料として、ＬｉＣｏＯ₂ を９２．７１重量％、アセチレンブラックを３．２６重量％、炭酸水素ナトリュウムを０．９３重量％、さらに結着剤としてポリビニリデンフロライドを１重量％、エチルヘキシルアクリレートを主体とするアクリル酸との共重合体を１．６６重量％、カルボキシメチルセルロースを０．４４重量％加え、水を媒体として混練して正極合剤用スラリーを作製した。得られたスラリーを厚さ２０μｍのアルミニウム箔（集電体）の両面に上記と同じ方法で塗布、乾燥し、集電体を除く厚みが２４６μｍの正極シートを作製した。上記の負極シートと同様な固定クラウンのローラー対でプレスし、集電体を除く厚みが１５３μｍの帯状正極シートを作製し表２の結果を得た。
【００６３】
【表２】

【００６４】
表１、表２の結果からプレスローラーのクラウン量を制御することにより、塗布幅方向の空隙率の変動を小さくできることは明らかである。クラウン量が０μｍでは空隙率の変動量が大きく、クラウン量が４５μｍと大きすぎても空隙率の変動量が大きくなってしまう。クラウン量が１μｍ以上４０μｍ以下であれば、空隙率の変動量が５％以下と小さく、好ましい。
【００６５】
（電極シートの裁断）
次に、電池性能について説明する。上記のプレスした負極シートおよび正極シートを２３０℃で２０分間熱処理した後、負極は５４ｍｍ、正極は５５．５ｍｍ幅にスリットした。
【００６６】
正極シートは、Ｃ−１を用い、８スリットをサンプルとし、それぞれＣ−１ａ〜Ｃ−１ｈとした。それぞれの空隙率の平均値は、２１、２４、２７、３０、３２、３０、２７、２５％であった。負極シートはＡ−２を用い、スリット後、空隙率の平均値が２１％のスリットを８枚裁断して準備した。
【００６７】
（シリンダー電池の組立）
上記負極シートおよび正極シートのそれぞれの端部にニッケル、アルミニウムのリード板をスポット溶接した後、露点−４０℃以下の乾燥空気中で２３０℃３０分間脱水乾燥した。
【００６８】
さらに、図４に示すように、脱水乾燥済み正極シート（８）、微多孔性ポリプロピレンフィルムセパレーター（セルガード２４００）、脱水乾燥済み負極シート（９）およびセパレーター（１０）の順で積層し、これを巻き込み機で渦巻き状に巻回した。この巻回体を負極端子を兼ねるニッケルメッキを施した鉄製の有底シリンダー型電池缶（１１）に収納した。
【００６９】
さらに、１リットル当たりＬｉＰＦ₆ とＬｉＢＦ₄ を各々０．９，０．１ｍｏｌ含有し、溶媒がエチレンカーボネート、ブチレンカーボネートとジメチルカーボネートの容量比が２：２：６である混合液からなる電解質（１５）を電池缶（１１）に注入した。
【００７０】
正極端子を有する電池蓋（１２）をガスケット（１３）を介してかしめてシリンダー型電池を作製した。なお、正極端子（１２）は正極シート（８）と、電池缶（１１）は負極シート（９）とあらかじめリード端子により接続した。なお、（１４）は安全弁である。
【００７１】
８枚の正極シートＣ−１ａ〜Ｃ−１ｈをそれぞれ用いて８本の電池を作製した。８本の電池は、全て上記の負極シートＡ−２をスリットしたものを負極シートとして用いた。上記のようにして作製した８本の電池を、４．１Ｖまで充電後、電流０．５ｍＡ／ｃｍ² で２．８Ｖまで放電した時の放電容量のバラつきが５％あり、電流を５ｍＡ／ｃｍ² とした時は放電容量のバラつきが９％に増加した。
【００７２】
一方、正極シートＣ−２をスリットし、空隙率が２１〜２３％のサンプルを使用した電池の場合は、電流０．５ｍＡ／ｃｍ² の時の放電容量のバラつきが１．５％、電流５ｍＡ／ｃｍ² の時の放電容量のバラつきが２％であった。
【００７３】
正極シートＣ−２は、正極シートＣ−１よりも空隙率の変動量が小さい。電池は、正極シートＣ−１を使用した時よりも正極シートＣ−２を使用した時の方が放電容量のバラつきが小さく、良好な性能を発揮する。電池に使用する電極シートは、空隙率の変動量が小さいことが好ましい。空隙率の変動量は、５％以内が好ましい。
【００７４】
実施例−２
（正極シートの作製）
実施例−１の正極シートと同じ材料を用いて正極合剤用スラリーを作製し、そのスラリーを厚さ２０μｍのアルミニウム箔（集電体）の両面に実施例−１と同じ方法で塗布、乾燥し、集電体を除く厚みが２７０μｍの正極シートを作製した。その後、図２に示したプレスローラーを用いてプレスし、集電体を除く厚みが２３５μｍの帯状正極シートを作製した。表３に、油圧シリンダによる油圧荷重を変化させてプレスを行なった結果を示す。
【００７５】
【表３】

【００７６】
油圧シリンダ荷重を大きくすれば、ローラーのクラウン量を大きくすることができる。油圧シリンダ荷重を制御することにより、少なくとも０〜４５μｍの広範囲にわたってクラウン量を設定することができる。また、実施例−１の固定クラウンのローラーの場合と同様に、クラウン量を１μｍ以上４０μｍ以下に設定すれば、空隙率の変動量を５％以下と小さくすることができ、好ましい。
【００７７】
【発明の効果】
本発明のように、塗布幅方向の電極空隙率の変動量が５％以内になるようにシート状電極を製造することにより、放電容量のバラつきが小さい電池を得ることができる。
【図面の簡単な説明】
【図１】プレスローラーの模式図である。
【図２】実施例に使用したプレスローラーの断面図である。
【図３】他のプレスローラーの模式図である。
【図４】実施例に使用したシリンダー型電池の断面図を示したものである。
【符号の説明】
８ 正極シート
９ 負極シート
１０ セパレーター
１１ 電池缶
１２ 電池蓋
１３ ガスケット
１４ 安全弁
１５ 電解液
１６ ＰＴＣ素子
２１ プレスロール
２２ 軸
２３ 軸受
２５ スタンド
２６ つり輪
２８ 油圧シリンダ
３１ プレスロール
３２ 軸
３３ 油[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an electrode sheet, and more particularly to a method for pressing an electrode sheet that can make the porosity distribution in the electrode sheet uniform.
[0002]
[Prior art]
It is known that the ratio of voids in the electrode greatly affects battery performance. In particular, in a battery using a nonaqueous solvent as an electrolyte, such as a lithium nonaqueous electrolyte secondary battery, it is important to control the porosity in order to obtain an appropriate discharge capacity and cycle characteristics.
[0003]
To control the porosity, there is a method to adjust the size and mixing ratio of the active material, conductive material, binder, etc. in the electrode mixture, but changing the mixing ratio will change the amount of electrode active material. It is not preferable. Therefore, a method of changing the porosity by mechanical compression is used.
[0004]
For example, Japanese Laid-Open Patent Publication No. 5-290833 proposes setting the porosity of a negative electrode made of a carbon material from 25% to 40%. As a method for controlling the porosity, a method of applying pressure after coating is proposed. In particular, compression by a roll press is described. However, when the pressure of the press is increased, the end of the electrode is further compressed, and there is a drawback that the active material in the mixture is sometimes crushed. In addition, the porosity tends to vary in the width direction of the electrode. For this reason, there has been a problem that a battery having uniform characteristics cannot be stably obtained.
[0005]
[Problems to be solved by the invention]
The subject of this invention is providing the manufacturing method which makes the porosity of the electrode obtained by apply | coating an electrode mixture on an electrical power collector uniform over the whole electrode, or the battery using these electrodes.
[0006]
[Means for Solving the Problems]
  According to one aspect of the present invention, a method for producing a sheet-like electrode includes a step of applying an electrode mixture capable of reversibly occluding and releasing lithium to an aluminum foil which is a sheet-like current collector, and the electrode mixture And a step of controlling the electrode porosity with a press machine having a pair of upper and lower press rolls, the electrode porosity is 10% or more and 40% or less, and the electrode gap in the coating width direction The rate fluctuation amount is controlled within 5%, and the crown amount of the portion in contact with the electrode is controlled to 1 μm or more and 40 μm or less by displacing the shafts of the pair of upper and lower press rolls.
  According to another aspect of the present invention, there is provided a method for producing a sheet-like electrode, the step of applying an electrode mixture capable of reversibly occluding and releasing lithium to a copper foil which is a sheet-like current collector, After the application of the electrode mixture, a process using a press machine having a pair of upper and lower press rolls to control the electrode porosity, the electrode porosity is 10% or more and 40% or less, and the coating width direction The amount of variation in the electrode porosity is controlled to within 5%, and the crown amount of the portion in contact with the electrode is controlled to 1 μm or more and 40 μm or less by displacing the axis of the pair of upper and lower press rolls. .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Next, although the preferable aspect of this invention is divided and demonstrated to a term, this invention is not limited to these.
[0008]
(1) A sheet-like electrode in which an electrode mixture is applied onto a sheet-like current collector, and the variation of the electrode porosity in the coating width direction is within 5%. Electrode manufacturing method.
[0009]
(2) The method for producing a sheet-like electrode according to item 1, wherein the electrode porosity is 10% or more and 40% or less, and the variation amount of the electrode porosity in the coating width direction is within 5%.
[0010]
(3) The method for producing a sheet-like electrode according to item (1) or (2), wherein the electrode porosity is controlled by applying treatment with a press machine having a pair of upper and lower press rolls after application of the electrode mixture.
[0011]
(4) The method for producing a sheet-like electrode according to item 3, wherein a pair of upper and lower press rolls having a crown amount of 1 μm or more and 40 μm or less at a portion in contact with the electrode of the press roll is used.
[0012]
(5) The interior of the press roll is divided into three or more chambers, each of which is connected to a hydraulic cylinder, and the crown amount of the press roll is controlled by controlling the hydraulic pressure in each chamber. The manufacturing method of the sheet-like electrode of description.
[0013]
(6) The method for producing a sheet-like electrode according to item 3, wherein the crown amount of the portion in contact with the electrode is controlled to 1 μm or more and 40 μm or less by displacing the pair of upper and lower press rolls.
[0014]
(7) The method for producing an electrode sheet according to item 6, wherein the shaft of the press roll is displaced by applying hydraulic pressure with a hydraulic cylinder.
[0015]
(8) A positive electrode sheet and a negative electrode sheet containing a material capable of reversibly inserting and extracting lithium, a nonaqueous electrolyte containing a lithium salt, and a nonaqueous secondary battery having a separator, wherein the positive electrode sheet and the negative electrode sheet are item 1 A non-aqueous secondary battery, wherein the non-aqueous secondary battery is an electrode sheet manufactured according to any one of No. 7 to No. 7.
[0016]
Hereinafter, embodiments of the present invention will be described in detail. The porosity of the electrode can be calculated by measuring the thickness of the electrode and the specific gravity of the electrode material. The porosity is often 20% to 60% immediately after the application and drying of the electrode mixture, and this is compressed by the method described below. The porosity after compression is preferably 10% or more and 40% or less, and particularly preferably 15% or more and 30% or less. If it is 10% or less, the penetration of the non-aqueous electrolyte into the electrode is slow, and if it is 40% or more, the volumetric energy density at the time of battery discharge is reduced. The value of the porosity here is an average value for the entire surface of the mixture layer on the electrode.
[0017]
The porosity is desirably uniform over the entire surface of the electrode, and is particularly important for extending the cycle life in a high capacity type such as a lithium ion secondary battery. The variation amount of the porosity in the width direction of application (the short direction of the sheet-like electrode) is preferably within 5%, particularly preferably within 3%. The variation amount of the porosity is expressed by (maximum porosity value−minimum porosity value).
[0018]
In order to compress the electrode after application, a planar press or a roller-type press may be used. In order to continuously manufacture the electrodes, it is preferable to use a press roller. In order to make the porosity in the width direction constant, it is necessary to make the pressing pressure per unit area of the electrode constant. Unit area (1cm²) Is preferably 0.1 to 15 t, particularly preferably 0.5 to 8 t. When a pressure of 15 tons or more is applied, problems such as crushing of particulate materials such as active materials in the electrode occur, and at a pressure of 0.1 t or less, the porosity of the electrode cannot be substantially lowered.
[0019]
In order to make the pressing pressure in the width direction constant, it is preferable to use a pair of upper and lower press rolls in which the crown amount of the portion that contacts the electrode of the roller is 1 μm or more and 40 μm or less. The crown amount is more preferably 2 μm or more and 30 μm or less, and particularly preferably 3 μm or more and 25 μm or less. The crown amount is the difference between the distance from the center line of the roller to the outer periphery of the central portion and the distance to the outer periphery of the roller end portion. The shape of the portion of the roller that contacts the electrode is convex with respect to the electrode. The roller may be symmetrical with the electrode side opposite to the electrode side, or may be similar or linear.
[0020]
It is mechanically easiest to use a so-called drum-type roller for the roller pair, but it is necessary to change to a roller with a different crown amount depending on the thickness or width of the electrode, etc., and production efficiency in the manufacturing process is good Absent.
[0021]
The most preferable pressing method is a method in which the crown shape of the roller can be changed in accordance with the amount of deflection by various compression loads with a set of rollers without changing the pressing roller. The method will be described below.
[0022]
FIG. 1 is a diagram schematically showing a press roller. FIG. 1A shows the press roller when the crown amount is 0, and FIG. 1B shows the press roller when the crown amount is given. FIG. 2 corresponds to FIG. 1 and shows a press roller that is actually used. FIG. 2A is a view of the press roller as viewed from the front, and is a cross-sectional view cut along the center line of the roller. FIG. 2B is a view of the press roller as viewed from the side, and is a cross-sectional view taken along the line AA in FIG.
[0023]
The upper press roll 21a and the lower press roll 21b constitute a roll pair, and compress the electrode sheet so as to sandwich the electrode sheet therebetween. The upper press roll 21a has a shaft 22a and is rotatably supported. The bearing 23a rotatably supports the shaft 22a at both ends of the upper press roll 21a. The bearing 23a is fixed by a stand 25a. The suspension ring 26a has a bearing inside, and rotatably supports the shaft 22a outside the bearing 23a.
[0024]
In the lower press roll 21b, the shaft 22b is rotatably supported by the bearing 23b and the suspension ring 26b as described above. The bearing 23b is fixed by a stand 25b.
[0025]
The hydraulic cylinder 28 connects the upper suspension ring 26a and the lower suspension ring 26b. When no hydraulic pressure is applied to the hydraulic cylinder 28, as shown in FIG. 1A, the central axis 24a of the upper shaft 22a and the central axis 24b of the lower shaft 22b are substantially straight. At this time, both the press rolls 21a and 21b have a crown amount of zero.
[0026]
When hydraulic pressure is applied to the hydraulic cylinder 28, as shown in FIG. 1 (B), a load acts in the direction of expanding the upper and lower suspension rings 26a and 26b. Since the bearings 23a and 23b are fixed by the stands 25a and 25b, respectively, the shafts 22a and 22b (and the shaft centerlines 24a and 24b) bend around the bearings 23a and 23b, respectively. Due to this load, the upper press roll 21a has a downwardly convex shape, and the lower press roll 21b has an upwardly convex shape. The press rolls 21a and 21b each have a crown shape having a crown amount LL. Even if the press roll is not replaced, the desired crown amount LL can be set by controlling the hydraulic load of the hydraulic cylinder 28 using the pair of press rolls 21a and 21b. If the crown amount LL is appropriately set according to the thickness or width of the electrode, the porosity can be made substantially constant in the width direction for any electrode.
[0027]
If the center line of the axis of the press roll is displaced, the crown amount can be changed. In order to displace the center line of the shaft of the press roll, the method is not limited to the method using a hydraulic cylinder, and other methods may be used.
[0028]
FIG. 3 is a diagram schematically illustrating another press roller. FIG. 3A shows the press roller when the crown amount is 0, and FIG. 3B shows the press roller when the crown amount is given.
[0029]
The upper press roll 31a and the lower press roll 31b are rotatably supported by shafts 32a and 32b, respectively. The inside of the upper press roll 31a is divided into, for example, five chambers in the direction of the shaft 32a, and oil 33a can be separately supplied to the respective chambers through the shaft 32a. By controlling the pressure of the oil 33a supplied to each room, the oil pressure in each room can be set independently. Similarly, the inside of the lower press roll 31b is divided into, for example, five chambers in the direction of the shaft 32b, and the hydraulic pressure in each chamber is set independently by controlling the pressure of the oil 33b supplied to each chamber. be able to.
[0030]
If the hydraulic pressures of all the rooms in the upper press roll 31a are made the same and the hydraulic pressures of all the rooms in the lower press roll 31b are made the same, as shown in FIG. 3A, the roll surfaces of the press rolls 31a and 31b Becomes flat and the crown amount becomes zero.
[0031]
On the other hand, for each of the press rolls 31a and 31b, if the hydraulic pressure in the middle chamber is increased and the hydraulic pressure in the chamber is decreased toward both ends, the volume of each chamber expands according to the hydraulic pressure as shown in FIG. The press rolls 31a and 31b both have a crown shape. The crown amount LL can be changed by controlling the oil pressure in each room.
[0032]
The number of rooms in each press roll is not limited to five, but is preferably at least three or more. Further, the crown amount may be changed by controlling the atmospheric pressure instead of the hydraulic pressure. The elastic modulus of the press roll may be changed instead of or together with the hydraulic pressure. For example, a press roll having a cylindrical wall that is thin at the center and becomes thicker toward both ends may be used.
[0033]
The electrode pressed by the above method is applied to all batteries using a rectangular electrode or electrode sheet. As an example, a non-aqueous secondary battery using lithium as an active material will be described in detail below. The positive and negative electrodes used in the non-aqueous secondary battery can be prepared by coating and molding a positive electrode mixture or a negative electrode mixture on a current collector. In addition to the positive electrode active material or the negative electrode material, the positive electrode or the negative electrode mixture can contain a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives, respectively. The coating solution and the electrode sheet can be prepared as follows.
[0034]
As a mixing / dispersing device used for preparing a coating solution of an electrode mixture (a positive electrode mixture or a negative electrode mixture), those of a general system are used. For example, horizontal cylindrical mixer, V-shaped mixer, double cone mixer, paddle mixer, ribbon mixer, planetary motion mixer, screw mixer, high-speed fluid mixer, horizontal single shaft A kneader, a horizontal double-shaft kneader, a vertical shaft kneader, or the like is used. Specifically, vertical ribbon mixer, horizontal ribbon mixer, vertical screw mixer, horizontal screw mixer, ball mill, pin mixer, double-arm kneader, pressure kneader, sand grinder, universal mixer, rake machine, cutter Although a mixer etc. are mentioned, it is not limited to this. Of course, the mixing and dispersing apparatus can be carried out singly or in combination.
[0035]
When the shape of the battery is a sheet, cylinder, or corner, the prepared electrode mixture is mainly applied onto a current collector, dried and compressed. The compression is performed, for example, by the above pressing method. The thickness, length and width of the coated layer of the coated sheet-like electrode are determined by the size of the battery, and the thickness of the coated layer is particularly preferably 1 to 600 μm in a compressed state after drying. The tension acting on the conductive support (current collector) is not particularly limited, but is preferably 10 g / cm to 2000 g / cm, and particularly preferably 20 g / cm to 1000 g / cm. Further, the support is controlled by an EPC (edge position controller) or the like when the traveling position varies.
[0036]
The support on which the electrode mixture is applied is transported to the drying chamber and the solvent is removed. The drying method is not particularly limited, and a general method can be used. Hot air, vacuum, infrared rays, far infrared rays, contact drum system, microwave, low humidity air, induction heating, etc. Or it can carry out in combination. The drying temperature is preferably 20 ° C to 350 ° C, and particularly preferably 40 to 200 ° C. The tension of the support is appropriately selected depending on the proof stress, flutter, curl, wrinkle, etc. of the support, but is preferably 10 g / cm to 2000 g / cm, and particularly preferably 20 g / cm to 1000 g / cm.
[0037]
The electrode mixture applied to the support is pressed by the above method after drying. The diameter of the press roller is preferably 100 mm or more and 3000 mm or less, and the press pressure is 200 kg / cm.²10000kg / cm²Is preferred. The pressing speed is preferably 0.1 m / min to 50 m / min. The pressing temperature is preferably room temperature to 200 ° C. The tension of the support is appropriately selected depending on the proof stress, flutter, curl, wrinkle, etc. of the support, but is preferably 10 g / cm to 2000 g / cm, and particularly preferably 20 g / cm to 1000 g / cm.
[0038]
When water remains in the electrode mixture, a dehydration step is provided as necessary to remove the water. As a dehydration method, a general method is used. In particular, hot air, vacuum, infrared rays, far infrared rays, microwaves, low-humidity air, induction heating, electron beams and the like can be used alone or in combination. The drying temperature is preferably in the range of 20 ° C to 350 ° C, particularly preferably 100 to 250 ° C. The water content is preferably 2000 ppm or less in the whole battery, preferably 500 ppm or less in the electrode mixture, and more preferably 200 ppm or less.
[0039]
The electrode sheet is cut into a necessary shape and used. As a cutting method, a conventional shearing method, a precision punching method, a burr-free shearing method, a flat pressing method, a top-bottom punching method, a burr gathering punching method, or the like is used. The cutting is preferably performed at a tension of 10 g / cm to 2000 g / cm, particularly preferably 20 g / cm to 1000 g / cm. The tension is appropriately selected according to the yield strength of the support, flutter, curl, wrinkle, electrode width accuracy, and the like.
[0040]
FIG. 4 is a cross-sectional view of a cylinder type battery. The battery shape can be applied to either cylinder or corner. The battery is formed by inserting the electrode sheets 8 and 9 wound together with the separator 10 into the battery can 11, electrically connecting the battery can 11 and the negative electrode sheet 9, and injecting and sealing the electrolytic solution 15. The battery lid 12 has a positive electrode terminal, and is fitted into the upper opening of the battery can 11 via the gasket 13. The electrode sheet 8 is electrically connected to the battery lid 12. At this time, the safety valve 14 can be used as a sealing plate. Furthermore, it is preferable to use a PTC (positive temperature coefficient) element 16 in order to guarantee the safety of the battery.
[0041]
The active material in the positive electrode may be any material that can insert and release light metals, but is preferably a lithium-containing transition metal oxide, more preferably Li_xCoO₂ , Li_xNiO₂ , Li_xCo_aNi_1-aO₂ , Li_xCo_bV_1-bO_z, Li_xCo_bFe_1-bO_z, Li_xMn₂ O_Four , Li_xMnO₂ , Li_xMn₂ O_Three , Li_xMn_bCo_2-bO_z, Li_xMn_bNi_2-bO_z, Li_xMn_bV_2-bO_z, Li_xMn_bFe_1-bO_z(Where x = 0.05 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, z = 1.5 to 5).
[0042]
Hereinafter, the light metal referred to in the present specification is an element belonging to Group 1A (excluding hydrogen) and Group 2A of the periodic table, preferably lithium, sodium, or potassium, and particularly preferably lithium.
[0043]
The active material in the negative electrode may be any material that can insert and release light metals, but preferably graphite (natural graphite, artificial graphite, vapor-grown graphite), coke (coal or petroleum), and burned organic polymer (polyacrylonitrile). Resin, fiber, furan resin, cresol resin, phenol resin), calcined mesophase pitch, metal oxide, metal chalcogenide, lithium-containing transition metal oxide and chalcogenide.
[0044]
In particular, an oxide or chalcogenide made of Ge, Sn, Pb, Bi, Al, Ga, Si, or Sb alone or a combination thereof is preferable. Furthermore, SiO known as a network former in these₂ , B₂ O_Three , P₂ O_Five , Al₂ O_Three , V₂ O_Five Those made amorphous by adding such as are particularly preferred. These may be of stoichiometric composition or non-stoichiometric compounds.
[0045]
Although the following can be mentioned as a preferable example of these compounds, It is not limited to these.
[0046]
GeO, GeO₂ , SnO, SnO₂ , SnSiO_Three , PbO, SiO, Sb₂ O_Five , Bi₂ O_Three , Li₂ SiO_Three , Li_Four Si₂ O₇ , Li₂ GeO_Three , SnAl_0.4B_0.5P_0.5K_0.1O_3.65, SnAl_0.4B_0.5P_0.5Cs_0.1O_3.65, SnAl_0.4B_0.5P_0.5K_0.1Ge_0.05O_3.85, SnAl_0.4B_0.5P_0.5K_0.1Mg_0.1Ge_0.02O_3.83, SnAl_0.4B_0.4P_0.4Ba_0.08O_3.28, SnAl_0.5B_0.4P_0.5Mg_0.1F_0.2O_3.65, SnAl_0.4B_0.5P_0.5Cs_0.1Mg_0.1F_0.2O_3.65, SnB_0.5P_0.5Cs_0.05Mg_0.05F_0.1O_3.03, Sn_1.1Al_0.4B_0.4P_0.4Ba_0.08O_3.34, Sn_1.2Al_0.5B_0.3P_0.4Cs_0.2O_3.5, SnSi_0.5Al_0.2B_0.1P_0.1Mg_0.1O_2.8, SnSi_0.5Al_0.3B_0.4P_0.5O_4.30, SnSi_0.6Al_0.1B_0.1P_0.1Ba_0.2O_2.95, SnSi_0.6Al_0.4B_0.2Mg_0.1O_3.2, Sn_0.9Mn_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.9Fe_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.3Ge_0.7Ba_0.1P_0.9O_3.35, Sn_0.9Mn_0.1Mg_0.1P_0.9O_3.35, Sn_0.2Mn_0.8Mg_0.1P_0.9O_3.35
Furthermore, the negative electrode material can be used by inserting a light metal, particularly lithium. The lithium insertion method is preferably an electrochemical, chemical or thermal method.
[0047]
The amount of lithium inserted into the negative electrode material may be close to the lithium deposition potential, but is preferably 50 to 700 mol% per the above preferred negative electrode material. 100 to 600 mol% is particularly preferable.
[0048]
The conductive agent in the positive electrode and the negative electrode is graphite, acetylene black, carbon black, ketjen black, carbon fiber or metal powder, metal fiber or polyphenylene derivative, and graphite and acetylene black are particularly preferable.
[0049]
The binder in the positive electrode and the negative electrode is polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl alcohol, starch, regenerated cellulose, diacetyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polyethylene, polypropylene , SBR (styrene-butadiene-rubber), ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, fluororubber, polybutadiene, polyethylene oxide, especially polyacrylic acid , Carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride are preferred. Yes. These are more preferably used as an aqueous dispersion latex having a particle size of 1 micron or less.
[0050]
The positive electrode and negative electrode support, that is, the current collector is made of aluminum, stainless steel, nickel, titanium, or an alloy thereof for the positive electrode, and copper, stainless steel, nickel, titanium, or an alloy thereof for the negative electrode. As forms, foil, expanded metal, punching metal, and wire mesh are used. In particular, an aluminum foil is preferable for the positive electrode and a copper foil is preferable for the negative electrode.
[0051]
The separator has only to have a large ion permeability, a predetermined mechanical strength, and an insulating thin film. The material is olefin polymer, fluorine polymer, cellulose polymer, polyimide, nylon, glass fiber, alumina fiber. And non-woven fabric, woven fabric, and microporous film are used as forms. In particular, the material is preferably polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, or a mixture of polyethylene and Teflon, and the form is preferably a microporous film. In particular, a microporous film having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferable.
[0052]
The electrolyte is an organic solvent such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, dioxolane, 1,3. -Dioxolane, formamide, dimethylformamide, nitromethane, acetonitrile, methyl formate, methyl acetate, methyl propionate, phosphoric acid triester, trimethoxymethane, dioxolane derivatives, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivatives, tetrahydro derivatives, A mixture of at least one of diethyl ether and 1,3-propane sultone, and LiClO as an electrolyte_Four , LiBF_Four , LiPF₆ , LiCF_Three SO_Three , LiCF_Three CO₂ , LiAsF₆ , LiSbF₆ , LiB_TenCl_Ten, Lower aliphatic lithium carboxylate, LiAlCl_Four , LiCl, LiBr, LiI, chloroborane lithium, and lithium tetraphenylborate in which one or more salts are dissolved are preferable. In particular, LiCF is used as a mixed solvent of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate._Three SO_Three LiClO_Four , LiBF_Four And / or LiPF₆ In which at least ethylene carbonate and LiPF are dissolved.₆ It is preferable to contain.
[0053]
The bottomed battery outer can is made of nickel-plated steel plate, stainless steel plate (SUS304, SUS304L, SUS304N, SUS316, SUS316L, SUS430, SUS444, etc.), nickel-plated stainless steel plate (same as above), aluminum or The alloys are nickel, titanium, and copper, and the shapes are a true circular cylinder, an elliptical cylinder, a square cylinder, and a rectangular cylinder. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate and a nickel-plated steel plate are preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum, or an alloy thereof is preferable.
[0054]
The gasket is made of an olefin-based polymer, a fluorine-based polymer, a cellulose-based polymer, a polyimide, or a polyamide, and is preferably an olefin-based polymer, particularly a propylene-based polymer, from the viewpoint of organic solvent resistance and low moisture permeability. Furthermore, a block copolymer of propylene and ethylene is preferable.
[0055]
The battery is covered with an exterior material as necessary. Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, and a plastic case. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be known.
[0056]
A plurality of batteries are assembled in series and / or in parallel as required, and stored in a battery pack. In addition to safety elements such as positive temperature coefficient resistors, temperature fuses, fuses and / or current interrupting elements, the battery pack also requires safety circuits (monitoring the voltage, temperature, current, etc. of each battery and / or the entire battery pack) In this case, a circuit having a function of interrupting current may be provided. In addition to the positive and negative terminals of the entire assembled battery, the battery pack should be provided with the positive and negative terminals of each battery, the entire assembled battery, the temperature detection terminal of each battery, the current detection terminal of the entire assembled battery, etc. as external terminals. You can also. The battery pack may incorporate a voltage conversion circuit (such as a DC-DC converter). The connection of each battery may be fixed by welding a lead plate, or may be fixed so that it can be easily attached and detached with a socket or the like. Further, the battery pack may be provided with display functions such as the remaining battery capacity, the presence / absence of charging, and the number of uses.
[0057]
Batteries are used in various devices. In particular, video movies, portable video decks with built-in monitors, movie cameras with built-in monitors, compact cameras, single-lens reflex cameras, disposable cameras, film with lenses, notebook computers, notebook-type word processors, electronic notebooks, mobile phones, cordless phones, whiskers, It is preferably used for electric tools, electric mixers, automobiles and the like.
[0058]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.
[0059]
Example-1
(Preparation of negative electrode sheet)
Negative electrode material SnB_0.5P_0.5O_Three77.5% by weight, flake graphite 17.01% by weight, lithium acetate 0.94% by weight, 3.78% by weight polyvinylidene fluoride as a binder, and 0.77% by weight carboxymethylcellulose The slurry for negative electrode mixture was prepared by kneading with water as a medium.
[0060]
The slurry was applied to both sides of a 18 μm thick copper foil (current collector) by an extrusion method and dried. The applied width of the obtained electrode was 500 mm, and the thickness of the dried electrode (the thickness of the slurry on both sides of the current collector) was 152 μm excluding the current collector. Thereafter, the thickness of the electrode was compression-molded to 91 μm using a roller press machine, excluding the current collector. The press roller is a pair of 500 mm diameter fixed crown rollers, and the crown amount is shown in Table 1. The porosity variation in the width direction in the table indicates the range of the porosity in the width direction, and the amount in the parentheses indicates the amount of variation (maximum value of porosity−minimum value of porosity).
[0061]
[Table 1]

[0062]
(Preparation of positive electrode sheet)
LiCoO as positive electrode material₂92.71% by weight, acetylene black 3.26% by weight, sodium hydrogen carbonate 0.93% by weight, polyvinylidene fluoride 1% by weight as a binder, and acrylic acid mainly composed of ethylhexyl acrylate 1.66% by weight of copolymer and 0.44% by weight of carboxymethylcellulose were added and kneaded using water as a medium to prepare a positive electrode mixture slurry. The obtained slurry was applied to both sides of an aluminum foil (current collector) having a thickness of 20 μm by the same method as described above and dried to prepare a positive electrode sheet having a thickness of 246 μm excluding the current collector. A belt-like positive electrode sheet having a thickness of 153 μm excluding the current collector was produced by pressing with a pair of fixed crown rollers similar to the above negative electrode sheet, and the results shown in Table 2 were obtained.
[0063]
[Table 2]

[0064]
From the results in Tables 1 and 2, it is clear that the variation in the porosity in the coating width direction can be reduced by controlling the crown amount of the press roller. When the crown amount is 0 μm, the variation amount of the porosity is large, and even when the crown amount is too large as 45 μm, the variation amount of the porosity becomes large. If the crown amount is 1 μm or more and 40 μm or less, the variation amount of the porosity is preferably as small as 5% or less.
[0065]
(Cut electrode sheet)
Next, battery performance will be described. The pressed negative electrode sheet and positive electrode sheet were heat-treated at 230 ° C. for 20 minutes, and then the negative electrode was slit to 54 mm, and the positive electrode was slit to 55.5 mm.
[0066]
As the positive electrode sheet, C-1 was used, 8 slits were used as samples, and C-1a to C-1h were used. The average value of each porosity was 21, 24, 27, 30, 32, 30, 27, 25%. The negative electrode sheet was prepared using A-2, and after slitting, 8 slits having an average porosity of 21% were cut.
[0067]
(Cylinder battery assembly)
Nickel and aluminum lead plates were spot welded to the respective ends of the negative electrode sheet and the positive electrode sheet, and then dehydrated and dried at 230 ° C. for 30 minutes in dry air having a dew point of −40 ° C. or lower.
[0068]
Further, as shown in FIG. 4, a dehydrated and dried positive electrode sheet (8), a microporous polypropylene film separator (Celgard 2400), a dehydrated and dried negative electrode sheet (9) and a separator (10) were laminated in this order. It wound in the shape of a spiral with a winding machine. The wound body was housed in an iron-bottomed cylinder type battery can (11) plated with nickel which also serves as a negative electrode terminal.
[0069]
In addition, LiPF per liter₆And LiBF_FourIn an amount of 0.9 and 0.1 mol each, and an electrolyte (15) made of a mixed solution in which the solvent was ethylene carbonate, butylene carbonate and dimethyl carbonate had a volume ratio of 2: 2: 6 was poured into the battery can (11). .
[0070]
A battery lid (12) having a positive electrode terminal was caulked through a gasket (13) to produce a cylinder type battery. The positive electrode terminal (12) was connected to the positive electrode sheet (8), and the battery can (11) was connected to the negative electrode sheet (9) in advance by a lead terminal. (14) is a safety valve.
[0071]
Eight batteries were produced using eight positive electrode sheets C-1a to C-1h, respectively. All eight batteries used what slit said negative electrode sheet A-2 as a negative electrode sheet. Eight batteries manufactured as described above were charged to 4.1 V, and then the current was 0.5 mA / cm.²The discharge capacity variation when discharged to 2.8V at 5% is 5%, and the current is 5 mA / cm.², The discharge capacity variation increased to 9%.
[0072]
On the other hand, in the case of a battery using a sample in which the positive electrode sheet C-2 is slit and the porosity is 21 to 23%, the current is 0.5 mA / cm.²Discharge capacity variation at 1.5%, current 5 mA / cm²The variation in discharge capacity at that time was 2%.
[0073]
The positive electrode sheet C-2 has a smaller variation in porosity than the positive electrode sheet C-1. The battery exhibits better performance when the positive electrode sheet C-2 is used than when the positive electrode sheet C-1 is used, and the variation in the discharge capacity is smaller. The electrode sheet used in the battery preferably has a small variation in porosity. The variation amount of the porosity is preferably within 5%.
[0074]
Example-2
(Preparation of positive electrode sheet)
Using the same material as the positive electrode sheet of Example-1, a slurry for positive electrode mixture was prepared, and the slurry was applied to both sides of an aluminum foil (current collector) having a thickness of 20 μm by the same method as in Example-1. Then, a positive electrode sheet having a thickness of 270 μm excluding the current collector was produced. Then, it pressed using the press roller shown in FIG. 2, and produced the strip | belt-shaped positive electrode sheet whose thickness except a collector is 235 micrometers. Table 3 shows the results of pressing while changing the hydraulic load by the hydraulic cylinder.
[0075]
[Table 3]

[0076]
If the hydraulic cylinder load is increased, the crown amount of the roller can be increased. By controlling the hydraulic cylinder load, the crown amount can be set over a wide range of at least 0 to 45 μm. Similarly to the case of the fixed crown roller of Example 1, it is preferable that the crown amount is set to 1 μm or more and 40 μm or less because the variation amount of the porosity can be reduced to 5% or less.
[0077]
【The invention's effect】
By manufacturing the sheet-like electrode so that the variation amount of the electrode porosity in the coating width direction is within 5% as in the present invention, a battery with a small variation in discharge capacity can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of a press roller.
FIG. 2 is a cross-sectional view of a press roller used in Examples.
FIG. 3 is a schematic view of another press roller.
FIG. 4 is a cross-sectional view of a cylinder type battery used in Examples.
[Explanation of symbols]
8 Positive electrode sheet
9 Negative electrode sheet
10 Separator
11 Battery can
12 Battery cover
13 Gasket
14 Safety valve
15 Electrolyte
16 PTC element
21 Press roll
22 axes
23 Bearing
25 stands
26 Ring
28 Hydraulic cylinder
31 Press roll
32 axes
33 oil

Claims (4)

Applying an electrode mixture capable of reversibly occluding and releasing lithium to an aluminum foil which is a sheet-like current collector;
After the application of the electrode mixture, a process with a press machine having a pair of upper and lower press rolls, and the step of controlling the electrode porosity,
The electrode porosity is 10% or more and 40% or less, the fluctuation amount of the electrode porosity in the coating width direction is controlled within 5%, and the shafts of the pair of upper and lower press rolls are displaced to contact the electrodes. A method for producing a sheet-like electrode, wherein the crown amount of the portion is controlled to 1 μm or more and 40 μm or less. Applying an electrode mixture capable of reversibly occluding and releasing lithium to a copper foil which is a sheet-like current collector;
After the application of the electrode mixture, a process with a press machine having a pair of upper and lower press rolls, and the step of controlling the electrode porosity,
The electrode porosity is 10% or more and 40% or less, the fluctuation amount of the electrode porosity in the coating width direction is controlled within 5%, and the shafts of the pair of upper and lower press rolls are displaced to contact the electrodes. A method for producing a sheet-like electrode, wherein the crown amount of the portion is controlled to 1 μm or more and 40 μm or less.  3. The method for producing a sheet-like electrode according to claim 1, wherein the axis of the press roll is displaced by applying hydraulic pressure by a hydraulic cylinder.  A positive electrode sheet and a negative electrode sheet containing a material capable of reversibly occluding and releasing lithium, a non-aqueous electrolyte containing a lithium salt, and a lithium non-aqueous secondary battery having a separator, wherein the positive electrode sheet and the negative electrode sheet are from A lithium non-aqueous secondary battery, which is an electrode sheet manufactured according to any one of 3 above.

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