METHOD FOR MANUFACTURING ALL-SOLID-STATE BATTERY

Abstract

[Problem] To lower electrical resistance by increasing the interfacial surface area and the adhesion between a current collector and an active material or an electrolyte, or between the active material and the electrolyte in an all-solid-state battery. In addition, to improve battery performance by eliminating or minimizing residual carbon originating from a binder. [Solution] According to the present invention, a slurry, composed of an electrode active material and a solvent, and a slurry, composed of electrolyte particles and a solvent, can be impacted against a target and thereby attached thereto to form a high-density layer and improve adhesion. Moreover, residual carbon is eliminated or minimized by eliminating or minimizing the content of binders, thereby improving battery performance.

Claims

1. A method for manufacturing an all-solid-state battery by laminating an electrode layer and an electrolyte layer for the all-solid-state battery, comprising forming interface formation between the electrode layer and the electrolyte layer by splaying an electrode slurry containing active material particles or a solvent and an electrode slurry containing electrolyte particles and a solvent, with impact.

2. A method for manufacturing an all-solid-state battery by forming an electrode by applying an electrode slurry to a current collector, comprising splaying a slurry containing active material particles and a solvent and a slurry containing electrolyte particles and a solvent to a current collector alternately with impact to laminate each slurry over and over.

3. The method of claim 1 or 2, wherein the electrode slurry or the electrolyte slurry is converted into particles by a particle generator or a fine particle generator, and the particles or groups of particles are transferred, impacted and adhere with a pressure difference to an object being at least one selected from the group consisting of the current collector, the electrode layer, and the electrolyte layer.

4. The method of any one of claims 1 to 3, wherein the electrode slurry or the electrolyte slurry contains a binder.

5. The method of any one of claims 1 to 3, wherein the surface of the active material particles or electrolyte particles is coated with a thin film of the binder in advance, and the solvent in the slurry is a poor solvent in relation to the binder.

6. The method of any one of claims 1 to 3, wherein in order to splay and adhere the electrode slurry or the electrolyte slurry or to transfer and adhere the particles converted by the particle generator to the object, the object is heated, and at least 95 percent of the solvent is volatilized within two seconds after the particles are adhered.

7. The method of any one of claims 1 to 7, wherein the splay or particle movement is done in pulses of 1 to 1000 Hz.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 shows a schematic diagram for active materials being splayed on an object (current collector), according to the present embodiment.

[0027] FIG. 2 shows a schematic diagram for different (e.g., conductive agent) particles being splayed onto the active material particles attached on the object, according to the present embodiment.

[0028] FIG. 3 shows a schematic cross-sectional view of two types of particles laminated together, according to the present embodiment.

[0029] FIG. 4 shows a schematic cross-sectional view of a current collector, positive electrode layer, electrolyte layer, negative electrode layer, and current collector laminated together, according to the present embodiment.

[0030] FIG. 5 shows a schematic cross-sectional view of electrode slurries being splayed onto the objects (current collector and electrolyte layer), according to the present embodiment.

[0031] FIG. 6 shows a schematic cross-sectional view of the splay on the objects (electrolyte layer and electrode layer), according to the present embodiment.

[0032] FIG. 7 shows a schematic cross-sectional view of the splay on the object (electrolyte layer), according to the present embodiment.

[0033] FIG. 8 shows a schematic cross-sectional view of the lamination by the alternated splaying of different materials onto the object (current collector) in a pulsed manner and with a time difference, according to the present embodiment.

DESCRIPTION OF EMBODIMENTS

[0034] Now, a preferred embodiment of the present invention will be described with reference to the drawings. However, the embodiment below is only an example for facilitating the understanding of the present invention. Addition, replacement, deformation, or the like executable by those skilled in the art can be made thereto without departing from the technical idea of the present invention.

[0035] The drawings schematically show the preferred embodiment of the present invention.

[0036] In FIG. 1, a slurry containing electrode active material particles and a solvent or a slurry containing active material particles, a solvent and a binder is sprayed from a spray head 21 onto a current collector 1 as an object, resulting that active material spray particles 2 are attached to the current collector 1, and then active material particles 2′ are made. The active material particles 2′ may be particles of the active material coated with the electrolyte material. Adhesion can be improved by pulsed spraying and attaching the spray particles to the current collector with impact at a high speed. The impact on the sprayed particles 2 is can be archived by keeping the distance between the object and the spray head close, e.g., 70 mm or less, and by pulsed splaying at a gas pressure of 0.15 to 0.3 MPa using a two-fluid nozzle with a splay pattern of a narrow splay angle, e.g., at 30 degrees or less. The number of pulses per second is preferably 10 Hz or higher for productivity. The shorter the distance and the narrower the splay pattern angle, the higher the impact.

[0037] FIG. 2 shows dispersed coating in a thin film by splaying a slurry (containing, e.g., electrolyte particles) different from that of FIG. 1 around and on top of the thin film (e.g., made of active material particles 2′) with a head 22. The splay of the active material from the head 21 in FIG. 1 and the splay of the electrolyte from the head 22 may be alternated to build up many layers in a thin film. Instead of the electrolyte particles, a solution or slurry including a conductive agent such as lithium iodide or at least one conductive agent selected from the group consisting of carbon particles, carbon fibers and carbon nanotubes, or a slurry of the mixture of them with the active material for the electrodes or the electrolyte particles is sprayed from the spray head 22 and then the sprayed particles 3 are adhered. Pore carbon and nanocarbon with large surface area, which is the conductive agent, are excellent. For example, when it has 2,000 square meters per gram or more in BET plot, and preferably 3,500 square meters or more, the electrode performance can be improved by encapsulating the sulfur or the active materials in the positive electrode and nano-level silicon in the negative electrode, in the nano-level pores in advance.

[0038] In FIG. 3, the electrode active material particles 2′ and electrolyte particles 3′ are laminated alternately. Weight ratio per unit area of each can be freely selected, and the ratio can be easily adjusted by especially performing pulsed spraying. Furthermore, a different spray head can be used to disperse and apply the desired amount of conductive agent around the electrode active material to achieve the adhesion.

[0039] In FIG. 4, a positive electrode layer 11 and a negative electrode layer 13 are laminated on both sides of an electrolyte layer 12, and the electrodes 11 and 13 are sandwiched between the current collectors 1 and 10. A laminated structure for the all-solid-state battery is completed by pressing it under heated condition or at room temperature. As the current collector, aluminum foil and copper foil are generally used for the positive electrode and the negative electrode, respectively, but not limited thereto, stainless steel sheet may be used depending on the types of the active material and electrolyte.

[0040] In FIG. 5, an electrolyte slurry and a negative electrode active material slurry are alternately sprayed from the spray heads 24 and 23, respectively, to form the negative electrode layer on the positive electrode current collector 1, the positive electrode layer 11, the electrolyte layer 12 and on the negative electrode current collector, and then pressing is performed using rolls 31 and 31′. When this pressing is performed in the subsequent process, the pressing pressure can be almost none or low. The rolls may be heated, and the current collector, electrode layer, and electrolyte layer may also be heated in advance to promote the volatilization of the solvent contained in the sprayed particles 4 and 5.

[0041] In FIG. 6, the electrolyte or an electrode active material slurry is sprayed to the interface between the electrolyte membrane layer 12 and the negative electrode layer 13 with a spray head 25. It is possible to increase adhesive strength of the interface by spraying the solvent or the like to instantly swell the binder or the like at the respective interface. It is moved by the rolls 31 and 31′ with or without the pressing pressure. There is no limit to the load, diameter, or number of press rolls.

[0042] In FIG. 7, the slurry for the electrolyte layer or the solvent is sprayed onto the electrolyte layers formed on both the positive and negative electrode layers on flexible current collectors. The effect is as described above.

[0043] In FIG. 8, the negative electrode active material slurry is sprayed onto the negative electrode current collector 10 from the spray head 23 in a pulsed manner to form sprayed particle clusters 7. On the other hand, the electrolyte slurry is pulsed sprayed from the spray head 24 to form sprayed particle clusters 8, and each sprayed particle cluster is alternately laminated on the negative electrode current collector. Preferably, it is thin and multi-layered. Similarly, the positive electrode active material slurry and the electrolyte slurry can be alternately laminated on the positive electrode current collector. Furthermore, an additional head, not shown in the figure, can be used to splay a small amount of conductive agent slurry in a pulsed manner alternately from the head 23 or 24.

[0044] In the embodiment, a head group including 100 to 200 spray heads arranged in one or more rows orthogonal to the direction of movement of an object with a width of, for example, 1500 mm can spray with impact in order to increase the productivity. If necessary, the head group can be moved back and forth (swung) in the head arrangement direction by, for example, 15 mm to sufficiently lap a pattern of, for example, 15 mm. The heads can be arranged for the required type of the slurry and for the desired number of laminations to meet the required speed.

[0045] The structure of the head can be simplified by using a wide roll with grooves, for example, every 10 millimeters in the width direction (disclosed in JPH08-309269A, of which inventor is the same as the present inventor). By rotating this roll with the grooves filled with the slurry, the slurry is be converted into particles by compressed gas, which can be adhered to the object. The speed of the object can theoretically be 100 meters per minute or more. Preferably, the number of roll devices to be placed orthogonal to the direction of movement of the object is determined according to the type of the slurry and the number of laminations. The technology disclosed by JPH06-86956A of which inventor is the same as the present inventor can also be used. A cylindrical screen or seamless belt with a width wider than the width of the object, equipped with numerous through holes (e.g., 150 micrometer diameter holes) filled with the slurry, may be used. When this cylindrical screen or seamless belt faces the object, the slurry is converted into fine particles to spray them by liquefied or compressed gas and evenly adhere to the entire surface of the object. Instead, a commercially available rotary screen for screen printing can be used to reduce the cost. The same effect can also be obtained by using a cylindrical pipe wider than the object, for example, with staggered holes of about 0.3 mm or 0.5 mm in diameter with a pitch of 1.5 mm. For the above two methods, the distance between the object and the location where the particles are blown out should be 70 millimeters or less to improve the impact effect. In the above two methods which also double as a volumetric feeding method, the line can be followed by changing the rotation speed, so there is no need for expensive pumps or controllers, and in the roll-to-roll process of a roll coater or rotary screen printer, equipment can be placed or manufacturing can be performed.

[0046] The slurry may be converted into particles and moved by pressure difference, and the particling may be done by inkjet. It can also be converted into particles by a disc or bell rotating atomizer used in the general coating field. Other methods such as atomization with a bubbler or ultrasonic waves and further refinement by hitting a rotating roll at close range with a spray stream are also acceptable. A particle group converted into particles may be transferred by carrier gas and attached to the object by differential pressure. The movement may be done in pulses to increase the adhesion efficiency and impact.

INDUSTRIAL APPLICABILITY

[0047] According to this embodiment, an all-solid-state battery with low interfacial resistance and high adhesiveness, which has a laminated structure including electrolyte, electrodes, and current collectors, can be manufactured with high quality.

DESCRIPTION OF THE REFERENCE NUMERAL

[0048] 1 Positive electrode collector [0049] 2, 4 Sprayed particle of electrode active material [0050] 2′ Electrode active material [0051] 3, 5 Sprayed particles of electrolyte [0052] 3′ Electrolyte particles [0053] 6 Sprayed particles of solvent [0054] 7 Sprayed particle cluster of electrode active material [0055] 8 Sprayed particle cluster of electrolyte [0056] 10 Negative electrode collector [0057] 11 Positive electrode layer [0058] 12 Electrolyte layer [0059] 13 Negative electrode layer [0060] 21, 22, 23, 24, 25 Spray head [0061] 31, 31′ Roll