JP4797459B2 - Electrode plate and battery manufacturing method - Google Patents

Description

  The present invention relates to an electrode plate and a battery manufacturing method using the same.

  In recent years, alloy-based negative electrode materials containing elements such as Si (silicon) and Sn (tin) have attracted attention as negative electrode active materials for increasing the capacity of nonaqueous electrolyte secondary batteries. For example, the theoretical discharge capacity of Si is about 4199 mAh / g, which is about 11 times the theoretical discharge capacity of graphite.

  However, these alloy-based negative electrode materials expand due to a large change in structure when occlusion of lithium ions. As a result, the active material particles are broken or the active material layer is peeled off from the current collector, whereby the electronic conductivity between the active material and the current collector is lowered, and as a result, battery characteristics such as cycle characteristics are lowered.

  In the negative electrode using the above-mentioned material as an active material, several techniques for suppressing the destruction of the active material layer and the decrease in conductivity that occur with expansion are disclosed (for example, Patent Document 1, Patent Document) 2, see Patent Document 3).

  Patent Document 1 discloses that a columnar structure can be formed by forming an active material thin film on a current collector having an uneven surface. Thereby, the cycle characteristics are improved by relieving stress due to expansion and contraction of the active material. As a method for forming irregularities on a current collector, it is disclosed that fine copper plating is performed after applying particulate copper on a metal foil by plating.

  Patent Document 2 discloses a battery electrode in which a thin film made of a metal alloyed with Li or an alloy containing the metal is formed on a current collector made of a material that is not alloyed with Li. In this example, an uneven negative electrode active material layer is formed in a predetermined pattern on a current collector by applying a photoresist method and a plating technique. Thereby, the space | gap is ensured between negative active materials.

Patent Document 3 discloses that an active material layer is formed on an adhesive resin layer made of a pattern-coated organic titanium compound, a silane coupling agent, or the like. This shows that the adhesive force and electrical connection between the current collector and the active material layer can be compatible and the cycle characteristics are improved. By applying this, the unevenness of the resin material can be formed on the substrate through a coating process, a cured process (patterning), a removing process, and an active material forming process. An active material layer having columnar particles can be formed by forming an active material layer thereover.
JP 2002-319408 A JP 2002-279972 A Japanese Patent Laid-Open No. 11-73947

  However, it is complicated to produce the voids between the columnar active material particles by the above-described conventional method because it undergoes a complicated process, and the active material is also laminated in the concave portion of the current collector, so that deformation occurs during charging and discharging. There is a problem that it is easy to do.

  In view of such a situation, the present invention provides a simple manufacturing method of an electrode plate that improves the cycle characteristics of a high-performance active material having a large expansion / contraction rate by not stacking an excess active material in the recess of the current collector. The purpose is to provide.

  In order to solve the above-described conventional problems, a method of manufacturing an electrode plate according to the present invention includes a step of applying a resin material on a current collector, a step of discretely curing a part of the resin material, and a current collector And a step of applying an active material layer that occludes and releases lithium ions in a mixed state of a cured resin and an uncured resin.

  In this manufacturing method, the uneven portion is formed on the surface of the current collector by curing the resin material, and the active material layer is formed by a vacuum process with the uncured resin remaining in the concave portion. Since the active material is formed and the uncured resin in the recesses continues to evaporate when the active material is formed, the active material hardly adheres to the central portion of the recess. Therefore, an excess active material is not laminated in the recess, and a void between the columnar active material particles can be easily produced.

  According to the production method of the present invention, it is possible to easily obtain an electrode plate that secures a sufficient gap for absorbing expansion and contraction of the active material between the columnar particles, and battery performance of a battery using the electrode plate. In particular, cycle characteristics can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a method for manufacturing an electrode plate according to Embodiment 1 of the present invention. In FIG. 1, a resin material is provided on the current collector in the first zone. In the first zone, the spray resin 4 is supplied onto the current collector 1 by the spray nozzle 3 to form the resin material 2. Next, the resin material 2 is irradiated with ultraviolet rays through the microlens array 7 in the second zone. The microlens array 7 condenses the ultraviolet rays in the form of lattice points at intervals of 10 μm, and the ultraviolet rays 6 become the condensed ultraviolet rays 8 by the microlens array 7, and a part of the resin material is in a cured state of lattice points. Resin 9 is formed. The current collector 1 in which the resin material 2 and the lattice-like cured resin 9 are thus formed proceeds to the third zone, and sputtered film of Si is formed as the active material layer 14 by the sputtered particles 13 from the sputter source 12. Receive. Most of the uncured resin material 2 is removed by physical or thermal impact of the sputtered particles 13 during the formation of the active material layer, and the formation of the active material layer and the removal of the uncured resin material proceed simultaneously. The back surface on which the active material is not formed can be taken out from the third zone after film formation by the same zones 1, 2, and 3 to obtain a negative electrode plate.

  By this manufacturing method, protrusions of the active material corresponding to the positions of the cured resin 9 can be formed on the surface of the current collector 1. By forming the active material layer 14 on the current collector 1, the active material layer 14 having an uneven shape corresponding to the uneven shape of the cured resin 9 is formed, but the uncured resin material is formed. Therefore, the active material layer 14 is formed simultaneously with the evaporation of the uncured resin material. Thereby, the dense adhesion of the material forming the active material layer 14 is inhibited, and the discontinuity around the convex portion of the active material layer 14 becomes more remarkable.

  As the resin material 2, various monomer materials can be used. Examples of the bonding group of the resin material 2 include an acrylic group and a vinyl group. Examples of the ultraviolet resin used in the present invention include tricyclodecane diacrylate and 1.9 nonanediol diacrylate. In order for the uncured component to exhibit appropriate volatility during film formation of the negative electrode active material, the monomer molecular weight is preferably 100 to 10,000, and more preferably 200 to 2,000.

  As a method of disposing the resin material 2 on the current collector 1, a general method such as a spray method, a vapor deposition method, an ink jet method, or a gravure coating method that can apply the resin material 2 thinly can be used. Among these methods, the spray method is a preferable method from the viewpoint of efficiency because the resin material 2 can be provided on the current collector 1 with one or several to several tens of nozzles. Various spray nozzles can be used in this method. Among them, a full cone nozzle and a perforated straight nozzle are preferable because uniform imparting property of the resin material can be easily obtained.

  The vapor deposition method is also a preferable method. Among them, the thermal vapor deposition method has a simple configuration, can be applied when the resin material 2 is applied to a large area, and is suitable for process continuity with electron beam curing by using a vacuum process. The resin material 2 is provided on the current collector by heating the monomer in a heating container. As a method for heating the container, heater heating, induction heating or other various methods can be used.

  As a means for discretely curing the resin material 2 on the current collector 1, general techniques such as thermal curing, photocuring, and ultraviolet curing can be used. Among these, ultraviolet curing or electron beam curing is preferable from the viewpoint of curing in a large area in a short time and according to the irradiation pattern position.

  When performing ultraviolet curing, an array of micro lenses may be used, and the array of micro lenses may be disposed between the ultraviolet radiation source and the current collector 1 provided with the resin material 2. By this method, the ultraviolet energy can be applied partially rather than uniformly over the entire surface of the resin material 2 applied on the current collector 1, so that the cured state can be discretely applied on the current collector 1. Resin 9 can be formed. The hardened resin 9 can be discretely formed on the current collector 1 by arranging the fine grid close to the current collector provided with the resin material 2 and performing ultraviolet irradiation. Ultraviolet irradiation is performed by condensing and irradiating ultraviolet rays having a wavelength of 0.1 to 0.4 μm, particularly 0.2 to 0.4 μm, through the microlens array 7. Moreover, the microlens array 7 used for this method can use what was formed on the glass substrate using the photolithographic technique. The lattice point-shaped light collection position pitch is 2 to 50 μm, preferably 5 to 20 μm.

  When performing electron beam curing, a deflection coil that bends the trajectory of the electron beam may be used. By this method, the irradiation position of the electron beam can be freely controlled. The irradiation position of the electron beam is controlled by applying a stepped electrical signal to the deflection coil. The electron beam deflection coil includes, for example, an X-axis scanning coil parallel to the current collector width and a Y-axis scanning coil orthogonal to the X-axis scanning coil. The repetitive scanning in the X-axis direction may be reciprocating scanning or one-way scanning. Lattice dot irradiation can be performed by a combination of scanning in the Y-axis direction synchronized with the traveling speed of the current collector. The scanning pitch is 5 to 50 μm, preferably 5 to 20 μm. As a result, the cured resin scattered on the current collector can be formed, for example, in the form of lattice points. The acceleration voltage during electron beam irradiation at that time is generally −0.5 to −20 kV, and the emission current of the electron beam is in the range of 1 to 100 mA. These conditions are determined according to the characteristics of the resin material 2.

  For the vacuum process for forming the active material layer 14, a general method such as vapor deposition, sputtering, or CVD can be used. The vapor deposition method or the sputtering method is preferable because the discontinuity of the active material layer 14 due to the uneven shape of the electric conductor 1 is ensured. Further, the vapor deposition method is particularly preferable from the viewpoint of efficiently forming the active material layer 14. As the vapor deposition method, electron beam vapor deposition having a reflection electron trap may be used, or resistance heating vapor deposition may be performed.

  As the negative electrode active material, Si, Sn, or a material that occludes and releases lithium ions such as oxides and nitrides thereof is used. Among them, since Si and Sn have a large degree of expansion, it is necessary to take a large gap between the columnar particles, and the improvement degree of the cycle characteristics of the battery using the electrode plate produced by the production method of the present invention is remarkable.

  When the active material layer 14 is formed by a vacuum process in a state where the uncured resin material and the cured resin 9 are mixed on the surface of the current collector 1, an active material is formed on the cured resin 9. The uncured resin is sequentially evaporated by the arrival of the active material. Therefore, the active material layer 14 grows in a granular form centering on the cured resin 9, and the active material particles adhere to the peripheral edges of the particles although the adhesion probability is somewhat low. As a result, a surface shape in which a portion where the cured resin 9 exists is convex and a portion where the uncured resin material exists is concave is formed. In particular, since the uncured resin material continues to evaporate for a long time at the central portion of the recess, the active material hardly adheres.

  The resin material 2 may contain conductive substance powder. By adopting such a configuration, it is possible to include a conductive material in the cured resin 9, thereby ensuring a more reliable electrical connection between the active material layer 14 and the current collector 1. Can be made.

  The resin material 2 may be a conductive resin. With this configuration, the electrical connection between the active material layer 14 and the current collector 1 can be made more reliable.

  It is preferable that the space | interval of the cured resin which exists discretely on a collector is 2-50 micrometers. By adopting such a configuration, it is possible to prevent the cured resin from being united without being scattered, and to prevent the unevenness of the current collector from becoming sparse, and without compromising the unevenness effect, the effects of the present invention can be achieved. It is easier to express.

  The height of the cured resin 9 scattered in a discrete manner is preferably in the range of 0.1 to 2 μm. With such a configuration, the unevenness effect of the current collector 1 is further ensured, and the cured resin 9 is prevented from falling off, so that the effects of the present invention are more easily exhibited.

  It is preferable that the area ratio of the discretely scattered cured resin 9 on the current collector 1 on which the active material layer 14 is formed is 12% or more and 75% or less. By setting it as such a structure, the uneven | corrugated effect of the electrical power collector 1 is made more reliable, and the effect of this invention is more easily expressed.

  The current collector 1 can be a general metal foil such as copper or nickel, or a metal film such as copper formed on a resin film. The thickness of the current collector 1 can be set to an arbitrary thickness, but from the viewpoint of cost, it is preferable to use a thin metal current collector layer. Thickness is necessary. From these points, the thickness of the current collector 1 is 2 to 20 μm.

The electrode obtained by the above method is represented by LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ through a separator containing an electrolyte solution in which an electrolyte such as LiPF ₆ is dissolved in a non-aqueous solvent such as ethylene carbonate or ethyl methyl carbonate. A battery is manufactured by facing a positive electrode having a positive electrode active material.

  In the first embodiment, it is not always necessary to separate the steps of the manufacturing method into individual zones, but the process can be stabilized by zoning and separating the processing space for each process step. .

(Embodiment 2)
FIG. 3 is a schematic diagram showing a method for manufacturing an electrode plate according to Embodiment 2 of the present invention. In FIG. 3, the resin material 2 is deposited from the resin evaporation source 17 onto the current collector 1 that is exhausted by the exhaust pump 11 and is unwound from the unwinding roll 15 in the vacuum chamber 10 partitioned by the shielding plate 23. Is done. Next, electron beam irradiation is performed from the electron beam source 18. Electron beam irradiation is performed in the form of dots while being scanned on the current collector surface by the XY deflection coil 19, and reciprocally scans mainly in the width direction of the current collector. In addition, a correction scan for displacement due to the movement of the current collector in the longitudinal direction is received in the length direction of the current collector. As a method of scanning the electron beam in the longitudinal direction (Y) of the current collector 1 and the direction (X) perpendicular thereto, there are a scanning method of reciprocating in the X direction and a method of scanning only one direction in the X direction. . FIG. 4 shows an image diagram of electron beam scanning. These may be selected according to conditions such as the unwinding speed of the current collector 1 and the width of the current collector 1. Although not shown, it is also possible to suspend the current collector and irradiate the electron beam in the form of lattice points on the XY plane.

  When such an electron beam scanning is performed using the deflection coil 19, a part of the resin material 2 becomes the resin 9 in a cured state in a lattice point shape. The current collector 1 on which the resin material 2 and the lattice-point cured resin 9 are thus formed passes through the guide roll 16 and then undergoes vapor deposition of the active material layer 14. The active material layer 14 can be deposited by heating, melting and evaporating the active material evaporation source 20 containing the active material and passing the electron trap 21 using a magnetic field or an electric field. The electron trap 21 can be omitted if the resin material 2 does not harden beyond the intended point-like irradiation range due to the influence of reflected electrons from the evaporation source.

  After the deposition of the active material layer 14 is completed, the current collector 1 is taken up by a take-up roll 22. Thus, the roll which formed the active material layer 14 in the single side | surface of the electrical power collector 1 is set to the unwinding roll 15, and the active material layer 14 is also formed in the back surface of the electrical power collector 1 by passing through the process similar to the above. Can be formed. In this way, the negative electrode plate is obtained after the film formation on the back surface is similarly completed.

  FIG. 2 is a schematic cross-sectional view of the electrode plate formed by the manufacturing method shown in the first and second embodiments of the present invention, and FIG. 5 is a schematic cross-sectional view of the electrode plate formed by the conventional manufacturing method. Show. In FIG. 5 of the conventional example, columnar active material layers 14 are formed on both surfaces of the current collector 1, and there are only fine voids between individual columnar particles. On the other hand, in FIG. 2 of the present invention, a cured resin 9 scattered on both surfaces of the current collector 1 is formed, and an active material layer 14 is further formed. The active material layer 14 has a concavo-convex shape due to the concavo-convex shape of the resin 9 in the cured state, and larger voids are formed between the columnar particles as compared with FIG.

  Hereinafter, the present invention will be described with reference to specific examples. In addition, this invention is not limited to the Example shown below.

Example 1
A rolled copper foil having a thickness of 15 μm was used as a current collector, and dimethylol tricyclodecane diacrylate represented by (Chemical Formula 1) as a resin material was applied thereon by spraying from a spray nozzle of a full cone nozzle. The application was performed after the resin material was in a sprayed state by opening a shutter installed between the full cone nozzle and the current collector for 2 seconds. It was confirmed beforehand by weight measurement that the resin material was given an average thickness of 1 μm when the shutter opening time was 2 seconds.

  Subsequently, the resin material was UV-cured. UV curing was performed using a low-pressure mercury ultraviolet lamp having a main peak at around 250 nm. The output of the ultraviolet lamp was 230 W, and the shutter between the current collector provided with the resin material and the ultraviolet lamp was shielded with a shutter, and the shutter was opened for 1 second to cure the resin material. At that time, a microlens array was arranged between the current collector provided with the resin material and the shutter so that only the lattice point-like portions of the resin material were cured. The lattice point interval at the center of the lens of the microlens array was 10 μm.

  The cured resin and the uncured resin material interspersed in lattice points were mixed on the current collector after the ultraviolet irradiation. The height of the scattered cured resin was about 1 μm. In this state, a Si thin film was formed by sputtering. Sputtering was performed by 2 kW magnetron sputtering to form a 5 μm thick Si thin film.

  After that, resin material was also applied to the back side of the current collector in the same process, UV curing of the resin with the microlens array arranged, and a mixture of cured resin and uncured resin material scattered in a grid of dots In this state, a Si thin film was formed to obtain a negative electrode plate.

In order to produce a positive electrode plate, 3 parts by weight of acetylene black as a conductive agent was mixed with 100 parts by weight of lithium cobalt oxide (LiCoO ₂ ) having an average particle diameter of 5 μm. The resulting mixture is kneaded by adding 4 parts by weight of an N-methyl-2-pyrrolidone (NMP) solution of polyvinylidene fluoride (PVdF), which is a binder, in terms of PVdF weight. An agent was obtained. This positive electrode mixture was applied to both surfaces of a current collector sheet made of an aluminum foil having a thickness of 10 μm, dried and then rolled to obtain a positive electrode plate having a total thickness of 110 μm.

The negative electrode with the lead connected to the negative electrode plate thus produced and the positive electrode with the lead connected to the positive electrode plate are wound with the separator facing each other, and then placed in the case, and an electrolyte is injected into the case. Then, the separator was impregnated, the case opening was sealed, and a secondary battery was produced. As the electrolyte, a non-aqueous electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate and propylene carbonate in a volume ratio of 1: 1 was used.

(Comparative Example 1)
A rolled copper foil having a thickness of 15 μm was used as a current collector, and tricyclodecane diacrylate was applied as a resin material thereon by spraying from a spray nozzle of a full cone nozzle. The application was performed after the resin material was in a sprayed state by opening a shutter installed between the full cone nozzle and the current collector for 2 seconds. It was confirmed beforehand by weight measurement that the resin material was given an average thickness of 1 μm when the shutter opening time was 2 seconds.

  Subsequently, the resin material was UV-cured. UV curing was performed using a low-pressure mercury ultraviolet lamp having a main peak at around 250 nm. The output of the ultraviolet lamp was 230 W, and the shutter between the current collector provided with the resin material and the ultraviolet lamp was shielded with a shutter, and the shutter was opened for 1 second to cure the resin material. At that time, a microlens array was arranged between the current collector provided with the resin material and the shutter so that only the lattice-like portions of the resin material were cured. The lattice point interval at the center of the lens of the microlens array was 10 μm.

  The cured resin and the uncured resin material interspersed in lattice points were mixed on the current collector after the ultraviolet irradiation. The height of the scattered cured resin was about 1 μm.

  In this state, the current collector is once taken out and immersed and washed with ethanol to remove at least most of the uncured resin material with the lattice-point cured resin remaining, and then wait for drying. A Si thin film was formed by sputtering. Sputtering was performed by 2 kW magnetron sputtering to form a 5 μm thick Si thin film.

  After that, the resin material is applied to the back surface of the current collector by the same process, the resin with the microlens array disposed thereon is UV-cured, and the Si thin film is formed with the uncured resin material removed, and the negative electrode plate It was.

  A secondary battery was produced in the same manner as in Example 1 except for the negative electrode thus produced.

(Comparative Example 2)
A rolled copper foil having a thickness of 15 μm was used as a current collector, and a Si thin film was directly formed thereon by a sputtering method. Sputtering was performed by 2 kW magnetron sputtering to form a 5 μm thick Si thin film. Thereafter, a Si thin film was also formed on the back surface of the current collector by the same process to obtain a negative electrode plate.

  A secondary battery was produced in the same manner as in Example 1 except for the negative electrode thus produced.

(Example 2)
A rolled copper foil having a width of 10 cm and a thickness of 12 μm unwound from a long roll in vacuum was used as a current collector, and 1.9 nonanediol diacrylate shown in (Chemical Formula 2) was vacuum-deposited thereon as a resin material. . Vapor deposition was performed by placing the resin material in a Teflon (registered trademark) container and evaporating by heating to 150 ° C. with a band heater. The opening width of the shielding plate was adjusted so that the resin material was formed with an average thickness of 0.5 μm on the current collector.

  Subsequently, electron beam curing of the resin material was performed. Electron beam curing was performed using an XY deflection coil at an acceleration voltage of -4 kV and an emission current of 10 mA. The lattice point interval for irradiating the electron beam was 30 μm. On the current collector after the electron beam irradiation, a cured resin and an uncured resin material scattered in lattice points were mixed. The height of the scattered cured resin was about 0.5 μm.

  In this state, a SiOx thin film was formed by vapor deposition. Vapor deposition was performed by electron beam vapor deposition with a reflective electron trap to form an 8 μm thick SiOx thin film. The value of x obtained by the combustion analysis method is about 0.8.

  After that, applying the resin material to the back surface of the current collector by the same process, UV curing of the resin, and forming a SiOx thin film with a mixture of cured resin and uncured resin material scattered in a grid of dots To obtain a negative electrode plate.

  A secondary battery was produced in the same manner as in Example 1 except for the negative electrode thus produced.

(Comparative Example 3)
A rolled copper foil having a width of 10 cm and a thickness of 12 μm unwound from a long roll in a vacuum was used as a current collector, and 1.9 nonanediol diacrylate was vacuum-deposited thereon as a resin material. Vapor deposition was performed by placing the resin material in a Teflon (registered trademark) container and evaporating by heating to 150 ° C. with a band heater. The opening width of the shielding plate was adjusted so that the resin material was formed with an average thickness of 0.5 μm on the current collector.

  Subsequently, electron beam curing of the resin material was performed. Electron beam curing was performed using an XY deflection coil at an acceleration voltage of -4 kV and an emission current of 10 mA. The lattice point interval for irradiating the electron beam was 30 μm. On the current collector after the electron beam irradiation, a cured resin and an uncured resin material scattered in lattice points were mixed. The height of the scattered cured resin was about 0.5 μm.

  In this state, the current collector is once taken out and immersed and washed with ethanol to remove at least most of the resin material in a state where the lattice-like cured resin remains, and then waits for drying to deposit a SiOx thin film. Formed by the method. Vapor deposition was performed by electron beam vapor deposition with a reflective electron trap to form an 8 μm thick SiOx thin film. The value of x determined by the combustion analysis method was about 0.8.

  Thereafter, application of the resin material, electron beam curing of the resin, and formation of the SiOx thin film in a state where the uncured resin material was removed were performed on the back surface of the current collector by the same process to obtain a negative electrode plate.

  A secondary battery was produced in the same manner as in Example 1 except for the negative electrode thus produced.

(Comparative Example 4)
A rolled copper foil having a width of 10 cm and a thickness of 12 μm unwound from a long roll in vacuum was used as a current collector, and a SiOx thin film was directly formed thereon by a vapor deposition method. Vapor deposition was performed by electron beam vapor deposition with a reflective electron trap to form an 8 μm thick SiOx thin film. The value of x determined by the combustion analysis method was about 0.8. Thereafter, a SiOx thin film was formed on the back surface of the current collector by the same process to obtain a negative electrode plate.

  A secondary battery was produced in the same manner as in Example 1 except for the negative electrode thus produced.

(Evaluation)
The cycle characteristics of the secondary batteries of Examples 1 and 2 and Comparative Examples 1 and 2 were measured. Cycling characteristics include repeated charging / discharging in the range of 4.2V to 2.5V at 0.1C (current at which 100% charging / discharging takes 10 hours each) with these batteries housed in an environmental test device at 25 ° C. The durability of the battery was examined. As the durability, the number of cycles in which the capacity could not be maintained at 80% of the initial capacity was compared. The results are shown in Table 1.

  As described above, in Example 1 and Example 2, a part of the resin material on the current collector is cured in a dot shape, and the cured resin and the uncured state scattered on the current collector The negative electrode active material thin film is formed in a state where the resin materials are mixed.

  On the other hand, in Comparative Example 1 and Comparative Example 3, a part of the resin material on the current collector is cured in the form of dots, and the negative electrode active material thin film is formed with the uncured resin material removed. ing. In Comparative Example 2 and Comparative Example 4, the negative electrode active material layer is formed in a state where neither a cured resin or an uncured resin material is present on the current collector.

  As can be seen from Example 1, Comparative Example 1 and Comparative Example 2 in the results of the cycle characteristics of (Table 1), the cycle characteristics improved by forming the negative electrode active material layer on the scattered cured resin is Further improvement is achieved by forming the negative electrode active material layer in a state where both the cured resin and the uncured resin material are present. Similar results are obtained from Example 2, Comparative Example 3 and Comparative Example 4.

  Further, in the same manner as in Example 1, when a fine grid is used instead of the microlens array, the 80% sustain cycle number is 45 cycles, which is improved compared to Comparative Example 1 and Comparative Example 2. Was recognized. As the fine grid, a SUS foil having a thickness of 8 μm and through-holes having a diameter of 25 μm arranged at lattice points with a center interval of 50 μm was used.

  The cycle characteristics of the secondary battery using the electrode plate obtained by the process of applying the active material layer in a vacuum process in a state where the cured resin and the uncured resin material are mixed are scattered. The reason for improvement is considered as follows. In the negative electrode active material layer, a concavo-convex shape grows on the surface of the active material layer according to the concavo-convex shape of the scattered cured resin. The amount of the active material material flying around by the vapor deposition method or the sputtering method is reduced around the convex portion. Therefore, the growth of the active material layer produces minute discontinuities such as minute gaps around the convex portion. At that time, as in the present invention, when the active material layer is formed with the resin material remaining, the formation of the active material layer and the evaporation of the remaining resin material occur simultaneously. As a result, dense adhesion of the material forming the active material layer is inhibited, and the discontinuity around the convex portion becomes more prominent in the active material layer. When surface microscope observation was performed in Example 1 and Comparative Example 1, Example 2 and Comparative Example 3, the gaps between the particles in Example 1 and Example 2 tended to be large.

  In Comparative Example 2 and Comparative Example 4 in which the negative electrode active material layer is formed in a state where neither the cured resin or the uncured resin material that is scattered on the current collector is present, voids between the particles are also present. It is considered that the cycle characteristics are extremely poor because the current collector and the negative electrode active material layer do not have an adhesive force due to the physical effect (throwing effect).

  Further, in Example 1, when carbon powder having a weight density of 10% is dispersed in the resin material and spray-applied, 1C (100% charge / discharge is performed for 1 hour in a state of being housed in an environmental test apparatus at 25 ° C. When charging / discharging was repeated in the range of 4.2 V to 2.5 V in terms of current, the discharge capacity was improved by 20%.

  This is probably because the carbon powder mixed and dispersed in the resin material improved the electrical connection between the negative electrode active material and the current collector, leading to an increase in discharge capacity. The method for improving the electrical connectivity between the negative electrode active material and the current collector is not limited to this example. As a result of curing of the resin material, the scattered cured resin has properties of the conductive resin. Show it.

  Such an effect is not limited to carbon powder, and equivalent cycle characteristics (60 cycles) are also obtained when Ni powder is used instead of carbon powder. Other metal powders may be used, and the polymer resin itself may be conductive when the resin material is in a polymerized and cured state.

  Further, in Example 1, the cycle characteristics were examined by changing the interval of the resin in the cured state by changing the lattice point interval at the center of the lens of the microlens array. The results shown in Table 2 were obtained. It was.

  Attempts were made to set the spacing between the scattered cured resins to 2 μm or less, but this could not be achieved by changing the lattice point spacing of the lens center of the microlens array or combining multiple lenses. For example, the resin was united without being scattered.

  On the other hand, when the interval between the scattered cured resins exceeds 50 μm, the effect of the cycle characteristic effect is remarkably lowered and thereafter becomes almost constant. If the distance between the cured resins exceeds 50 μm, the unevenness of the current collector becomes sparse and the effect on the entire active material is reduced. In addition, the cycle characteristics when the interval between the cured resins exceeds 50 μm is slightly improved as compared with Comparative Example 2 because the negative electrode active material layer is somewhat sparse due to the evaporation of the resin during film formation. It seems that it was because of Therefore, it is more preferable for the cycle characteristics to be improved that the interval between the scattered cured resins is approximately 2 to 50 μm.

  Moreover, when the space | interval of the cured resin scattered in Table 2 is 2-50 micrometers, the area ratio of the scattered cured resin which occupies on the electrical power collector in which an active material layer is formed is 12-75%. Therefore, it is more preferable for improving the cycle characteristics that the area ratio of the scattered cured resin on the current collector on which the active material layer is formed is 12% or more and 75% or less.

  Further, in Example 2, the cycle characteristics were examined by changing the height of the resin in the cured state, which was scattered by changing the application amount of the resin, and the results shown in Table 3 were obtained.

  If the height of the scattered cured resin is less than 0.1 μm, the cycle characteristics are equivalent to those of Comparative Example 4. This seems to be because the unevenness of the current collector is reduced and the expression of the unevenness effect is reduced. On the other hand, the cycle characteristics tend to deteriorate even when the height of the scattered cured resin exceeds 2 μm. Although the cause of this is not clear, when the height of the scattered cured resin is 4 μm, the cured resin may fall off from the current collector. Therefore, it is more preferable for improving the cycle characteristics that the height of the scattered cured resin is approximately in the range of 0.1 to 2 μm.

  As described above, according to the present invention, a metal such as Si or Sn, or an active material such as oxide or nitride, which theoretically absorbs or releases a large amount of ions but expands and contracts greatly with charge and discharge, is utilized. It is possible to do.

  In the embodiments and examples, the description has been made mainly on the assumption of the negative electrode plate. However, the electrode plate and the battery manufacturing method of the present invention are not limited to the negative electrode plate and the lithium ion secondary battery. For example, it is applicable also to a positive electrode plate. Further, it can be applied to batteries other than lithium ion secondary batteries and electrode plates having problems associated with expansion and contraction.

  The present invention provides an electrode plate that can withstand repeated use of a material having a large degree of expansion and contraction, and a method for manufacturing a battery. The electrode plate obtained by the production method of the present invention is not limited to the battery industry field and can be applied to all electrochemical devices.

The schematic diagram which shows the manufacturing method of the electrode plate in the 1st Embodiment of this invention Schematic sectional view showing the electrode plate of the secondary battery according to the first and second embodiments of the present invention. The schematic diagram which shows the manufacturing method of the electrode plate in the 2nd Embodiment of this invention. Schematic diagram showing an example of an electron beam scanning method in the third embodiment of the present invention Schematic sectional view showing an electrode plate of a secondary battery according to a conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current collector 2 Resin material 3 Spray nozzle 4 Spray resin 5 Ultraviolet lamp 6 Ultraviolet light 7 Micro lens array 8 Condensed ultraviolet light 9 Dotted hardening resin 10 Vacuum tank 11 Exhaust pump 12 Sputter source 13 Sputtered particle 14 Active Material layer 15 Unwinding roll 16 Guide roll 17 Resin evaporation source 18 Cured electron beam source 19 Deflection coil 20 Active material evaporation source 21 Electron trap 22 Winding roll 23 Shielding plate

Claims (12)

Applying a resin material on the current collector;
A step of discretely curing a part of the resin material;
A step of providing a vacuum process with an active material layer that occludes and releases lithium ions in a state where a cured resin and an uncured resin are mixed on the current collector;
A method for producing an electrode plate, comprising: The resin material is either an ultraviolet curable resin or an electron beam curable resin;
2. The method for producing an electrode plate according to claim 1, wherein: The resin material contains a conductive substance;
The method of manufacturing an electrode plate according to claim 1. The cured resin is a conductive resin;
The method of manufacturing an electrode plate according to claim 1. The step of discretely curing a part of the resin material irradiates ultraviolet rays discretely using an array of fine lenses or a fine grid;
The method of manufacturing an electrode plate according to claim 1. The step of discretely curing a part of the resin material uses a deflection coil that bends the orbit of the electron beam, and irradiates the electron beam discretely by applying a stepped electrical signal to the deflection coil. ,
The method of manufacturing an electrode plate according to claim 1. The vacuum process is either vapor deposition or sputtering;
The method for producing an electrode plate according to claim 1, wherein: The active material layer is Si or Sn or an oxide or nitride thereof;
The method of manufacturing an electrode plate according to claim 1. The area ratio of the cured resin on the current collector is 12% or more and 75% or less,
The method of manufacturing an electrode plate according to claim 1. The space between the cured resins is 2 to 50 μm,
The method of manufacturing an electrode plate according to claim 1. The height of the cured resin is in the range of 0.1 to 2 μm;
The method of manufacturing an electrode plate according to claim 1. The manufacturing method of the battery using the electrode plate obtained by the manufacturing method of the electrode plate in any one of Claims 1-11.

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