Electrode layer and all-solid-state battery

Abstract

To provide an electrode layer and the like capable of achieving both the high capacity of an all-solid battery and maintenance of the strength of an electrode layer.SOLUTION: A positive electrode layer 10 is a positive electrode layer 10 used for all-solid batteries that includes: a positive current collector 6; a positive electrode bonding layer 4 formed over the positive current collector 6, which contains at least a conductive agent; and a positive electrode mixture layer 11 formed over the positive electrode bonding layer 4, which contains at least a positive electrode active material 2 composed of a plurality of particles, a solid electrolyte 1 that has ionic conductivity, and a plurality of conductive fibers 3. The multiple conductive fibers 3 includes conductive fibers 3 positioned to connect adjacent particles of the positive electrode active material 2. The binder concentration contained in the positive electrode mixture layer 11 is less than 100 ppm, and the concentration of solvents contained in the positive electrode mixture layer 11 is 50 ppm or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electrode layer used in an all-solid-state battery and the all-solid-state battery. [Background technology]

[0002] In recent years, the trend toward lighter and more cordless electronic devices such as personal computers and mobile phones has led to a demand for the development of reusable secondary batteries. Secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lead-acid batteries, and lithium-ion batteries. Among these, lithium-ion batteries have attracted attention due to their lightweight, high voltage, and high energy density.

[0003] In the field of automobiles, such as electric vehicles and hybrid vehicles, the development of high-capacity secondary batteries is becoming increasingly important, and the demand for lithium-ion batteries is on the rise.

[0004] A lithium-ion battery is composed of a positive electrode layer, a negative electrode layer, and an electrolyte disposed between them. The electrolyte can be a liquid electrolyte, such as lithium hexafluorophosphate, dissolved in an organic solvent, or a solid electrolyte. Currently, widely used lithium-ion batteries are flammable because they use an organic solvent-containing electrolyte. Therefore, materials, structures, and systems are required to ensure the safety of lithium-ion batteries. By using a non-flammable solid electrolyte as the electrolyte, it is expected that the above-mentioned materials, structures, and systems can be simplified, resulting in increased energy density, reduced manufacturing costs, and improved productivity. Hereinafter, batteries using solid electrolytes will be referred to as "all-solid-state batteries."

[0005] Solid electrolytes can be broadly divided into organic solid electrolytes and inorganic solid electrolytes. Generally, the solid electrolytes used in the solid electrolyte layer and the solid electrolytes used to form the positive electrode layer or the negative electrode layer together with the active material are mainly inorganic solid electrolytes with high ionic conductivity at room temperature (e.g., 25°C). Examples of inorganic solid electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, and halide-based solid electrolytes. The ionic conductivity of these inorganic solid electrolytes at 25°C is, for example, 10 -4 ~10 -2 Patent Document 1 discloses an all-solid-state battery using an inorganic solid electrolyte in the solid electrolyte layer, the positive electrode layer, and the negative electrode layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-109747 Summary of the Invention [Problem to be solved by the invention]

[0007] Electrode layers such as positive electrode layers are structured without binders for bonding materials, eliminating the need for binders, which are insulating materials that impede battery operation, thereby improving the battery capacity of all-solid-state batteries. For example, the all-solid-state battery disclosed in Patent Document 1 includes electrode layers such as positive electrode layers and negative electrode layers that do not contain binders in order to improve battery characteristics. In binder-free electrode layers, for example, the solid electrolyte functions as a binder, maintaining the strength of the electrode layer to a certain extent. However, further improvements in strength are required to improve battery reliability, etc. Furthermore, to further improve battery capacity, it is necessary to ensure the strength of the electrode layer even when the amount of solid electrolyte functioning as a binder is reduced.

[0008] Therefore, the present disclosure provides an electrode layer etc. that can achieve both high capacity of an all-solid-state battery and maintaining the strength of the electrode layer. [Means for solving the problem]

[0009] An electrode layer according to one embodiment of the present disclosure is an electrode layer for use in an all-solid-state battery, comprising: an electrode current collector; an electrode contact layer including at least a conductive agent and formed on the electrode current collector; and an electrode mixture layer including at least an electrode active material composed of a plurality of particles, an ion-conductive solid electrolyte, and a plurality of conductive fibers and formed on the electrode contact layer, wherein the plurality of conductive fibers include first conductive fibers positioned so as to connect adjacent particles of the electrode active material, the electrode mixture layer having a binder concentration of 100 ppm or less, and the electrode mixture layer having a solvent concentration of 50 ppm or less.

[0010] An all-solid-state battery according to one embodiment of the present disclosure includes the above-described electrode layer. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to achieve both high capacity and maintaining the strength of the electrode layer of an all-solid-state battery. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view of an all-solid-state battery according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a cross section of a positive electrode layer in the embodiment. [Figure 3] FIG. 3 is a schematic diagram showing a cross section near the interface between the positive electrode bonding layer and the positive electrode mixture layer in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Summary of the Disclosure) An outline of one aspect of the present disclosure is as follows.

[0014] An electrode layer according to one embodiment of the present disclosure is an electrode layer for use in an all-solid-state battery, the electrode layer comprising: an electrode current collector; an electrode contact layer including at least a conductive agent and formed on the electrode current collector; and an electrode mixture layer including at least an electrode active material composed of a plurality of particles, an ion-conductive solid electrolyte, and a plurality of conductive fibers and formed on the electrode contact layer, wherein the plurality of conductive fibers include first conductive fibers positioned so as to connect adjacent particles of the electrode active material, the electrode mixture layer having a binder concentration of 100 ppm or less, and the electrode mixture layer having a solvent concentration of 50 ppm or less.

[0015] This results in an electrode mixture layer that is substantially free of binders and solvents, thereby improving battery capacity. Furthermore, the elongated first conductive fibers are positioned so as to connect adjacent electrode active material particles, thereby entangling the adjacent electrode active material particles and improving the strength of the electrode mixture layer. Therefore, the strength of the electrode mixture layer, which is substantially free of binders for adhering the materials of the electrode mixture layer, is maintained. Furthermore, the multiple conductive fibers are conductive, so they do not inhibit electronic conduction in the electrode mixture layer. Therefore, the electrode layer according to this embodiment can achieve both high capacity in an all-solid-state battery and maintained strength of the electrode layer.

[0016] Furthermore, for example, the first conductive fibers may pass through the solid electrolyte between adjacent particles of the electrode active material.

[0017] This allows the first conductive fibers to be entangled in the solid electrolyte between the particles of the electrode active material and connect the particles of the electrode active material, thereby improving the strength of the electrode mixture layer.

[0018] Furthermore, for example, the electrode layer may be a positive electrode layer or a negative electrode layer.

[0019] This makes it possible to realize a positive electrode layer or a negative electrode layer that can achieve both high capacity and strength retention in an all-solid-state battery.

[0020] Furthermore, for example, the plurality of conductive fibers may include conductive fibers having a fiber diameter of 30 nm or less and a fiber length that is 300 times or more the fiber diameter.

[0021] This makes it easier for the multiple conductive fibers to become entangled in the material of the electrode mixture layer, thereby effectively improving the strength of the electrode mixture layer.

[0022] Furthermore, for example, some of the plurality of conductive fibers may be interposed at the interface between the electrode contact layer and the electrode mixture layer, and the some of the conductive fibers may include second conductive fibers positioned so as to connect the electrode contact layer and the electrode active material, and third conductive fibers positioned so as to connect the electrode contact layer and the solid electrolyte.

[0023] As a result, the second conductive fibers and the third conductive fibers are positioned so as to connect the material of the electrode mixture layer and the material of the electrode contact layer, respectively, and become entangled with the material of the electrode mixture layer and the material of the electrode contact layer, reinforcing the adhesion between the electrode contact layer and the electrode mixture layer, thereby improving the adhesive strength at the interface between the electrode contact layer and the electrode mixture layer.

[0024] Furthermore, for example, the content of the plurality of conductive fibers in the electrode mixture layer may be 1 wt % or less with respect to the total weight of the electrode mixture layer.

[0025] This prevents a decrease in ionic conductivity in the electrode mixture layer due to a plurality of conductive fibers that do not have ionic conductivity, and thus prevents a decrease in battery capacity.

[0026] Moreover, an all-solid-state battery according to one aspect of the present disclosure includes the above-described electrode layer.

[0027] In this way, since the all-solid-state battery includes the electrode layer, it is possible to realize an all-solid-state battery that can achieve both high capacity and maintaining the strength of the electrode layer.

[0028] All-solid-state batteries according to embodiments will be described in detail below. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement and connection of the components, and processes shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0029] Furthermore, in this specification, terms indicating the relationship between elements, such as parallelism, terms indicating the shape of elements, such as rectangle, and numerical ranges are not expressions that express only the strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0030] In addition, each drawing is a schematic diagram in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present disclosure, and is not necessarily an exact illustration, and may differ from the actual shape, positional relationship, and proportion. In each drawing, the same reference numerals are used to denote substantially the same configurations, and duplicated explanations may be omitted or simplified.

[0031] Furthermore, in this specification, the terms "upper" and "lower" in the configuration of an all-solid-state battery do not refer to the upper direction (vertically upper) and lower direction (vertically lower) in absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in the stacking configuration. Furthermore, the terms "upper" and "lower" are applied not only to the case where two components are arranged in close contact with each other, but also to the case where two components are arranged with a gap between them, with another component present between them.

[0032] In this specification, a cross-sectional view is a view showing a cross section of the center of an all-solid-state battery cut in the stacking direction, that is, in the thickness direction of each layer.

[0033] (Embodiment) [1. All-solid-state battery] An all-solid-state battery 100 according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view of the all-solid-state battery 100 according to the present embodiment. Note that Fig. 1 omits illustration of the materials contained in each layer of the all-solid-state battery 100 and the fine structure of each layer.

[0034] 1 , the all-solid-state battery 100 of the present embodiment includes, for example, a positive electrode layer 10 having a positive electrode current collector 6, a positive electrode bonding layer 4 formed on the positive electrode current collector 6, and a positive electrode mixture layer 11 formed on the positive electrode bonding layer 4, a negative electrode layer 20 having a negative electrode current collector 7, a negative electrode bonding layer 5 formed on the negative electrode current collector 7, and a negative electrode mixture layer 21 formed on the negative electrode bonding layer 5, and a solid electrolyte layer 30 disposed between the positive electrode mixture layer 11 and the negative electrode mixture layer 21. The all-solid-state battery 100 has a structure in which the positive electrode current collector 6, the positive electrode bonding layer 4, the positive electrode mixture layer 11, the solid electrolyte layer 30, the negative electrode mixture layer 21, the negative electrode bonding layer 5, and the negative electrode current collector 7 are stacked in this order.

[0035] The all-solid-state battery 100 is manufactured, for example, by the following manufacturing method. First, the positive electrode layer 10, the negative electrode layer 20, and the solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20, each having the above-described configuration, are formed. Then, the positive electrode current collector 6 and the negative electrode current collector 7 are pressed from the outside at a pressure of, for example, 100 MPa or more and 1000 MPa or less, to manufacture the all-solid-state battery 100.

[0036] Each layer will be described in detail below.

[0037] [2. Positive electrode layer] The positive electrode layer 10 in this embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing a cross section of the positive electrode layer 10 in this embodiment.

[0038] The positive electrode layer 10 in this embodiment includes, for example, a positive electrode current collector 6 made of a metal foil or the like, a positive electrode bonding layer 4 formed on the positive electrode current collector 6, and a positive electrode mixture layer 11 formed on the positive electrode bonding layer 4. In this embodiment, the positive electrode mixture layer 11 includes a plurality of conductive fibers 3. The positive electrode layer 10 is an example of an electrode layer, the positive electrode bonding layer 4 is an example of an electrode bonding layer, and the positive electrode mixture layer 11 is an example of an electrode mixture layer.

[0039] [2.1. Positive electrode mixture layer] The positive electrode mixture layer 11 includes at least a positive electrode active material 2, a solid electrolyte 1, and a plurality of conductive fibers 3. The positive electrode active material 2 is an example of an electrode active material. The positive electrode mixture layer 11 does not include, for example, a binder that serves as an adhesive that bonds the materials of the positive electrode mixture layer 11 together. Here, "not including a binder" means that the positive electrode mixture layer 11 does not substantially include a binder, and means that the concentration of the binder included in the positive electrode mixture layer 11 is 100 ppm or less.

[0040] Furthermore, for example, no solvent (specifically, an organic solvent) is contained in the positive electrode mixture layer 11. Here, "no solvent is contained" means that the solvent is substantially not contained, and that the concentration of the solvent contained in the positive electrode mixture layer 11 is 50 ppm or less.

[0041] [2.1.1. Conductive fibers] As described above, the positive electrode mixture layer 11 includes a plurality of conductive fibers 3. The plurality of conductive fibers 3 improves the strength of the positive electrode mixture layer 11.

[0042] Since the positive electrode mixture layer 11 does not contain a binder that serves as an adhesive, the solid electrolyte 1 functions as an adhesive.

[0043] The solid electrolyte 1 and the positive electrode active material 2 in the positive electrode mixture layer 11 are bonded together by an anchor effect caused by the solid electrolyte 1 biting into the positive electrode active material 2 .

[0044] Furthermore, the solid electrolytes 1 in the positive electrode mixture layer 11 are bonded together by sintering the solid electrolytes 1.

[0045] If the amount of the positive electrode active material 2 is increased and the amount of the solid electrolyte 1, which acts as a binder, is decreased to further increase the battery capacity, the strength of the positive electrode mixture layer 11 will decrease. The plurality of conductive fibers 3, characterized by their thin and long shapes, will be entangled with the positive electrode active material 2 and the solid electrolyte 1, thereby improving the strength of the positive electrode mixture layer 11. In this embodiment, "the conductive fibers 3 are entangled" means, for example, that a portion of the conductive fibers 3 is in contact with the surface of the target material or is embedded in contact with the surface. Furthermore, "the conductive fibers 3 are entangled" may mean that the conductive fibers 3 are present so as to pass through the interior of the target material.

[0046] The plurality of conductive fibers 3 include, for example, the following conductive fibers 3.

[0047] A certain conductive fiber 3 is positioned, for example, to connect the positive electrode active material 2 and the solid electrolyte 1. The conductive fiber 3 is entangled with the positive electrode active material 2 and the solid electrolyte 1, connecting them together.

[0048] Furthermore, other conductive fibers 3 are positioned, for example, so as to connect adjacent particles of the positive electrode active material 2. The conductive fibers 3 are entangled with adjacent particles of the positive electrode active material 2, connecting the adjacent particles of the positive electrode active material 2. The particles of the positive electrode active material 2 connected by the conductive fibers 3 may be adjacent to each other. The conductive fibers 3 positioned so as to connect adjacent particles of the positive electrode active material 2 are an example of first conductive fibers. Furthermore, the conductive fibers 3 may be positioned so as to pass through the solid electrolyte 1 positioned between adjacent particles of the positive electrode active material 2, connecting the adjacent particles of the positive electrode active material 2. In this way, the conductive fibers 3 are also entangled with the solid electrolyte 1 between the particles of the positive electrode active material 2, thereby further improving the strength of the positive electrode mixture layer 11.

[0049] In this way, the strength of the positive electrode mixture layer 11 is improved by the plurality of conductive fibers 3 being entangled with the solid electrolyte 1 and the positive electrode active material 2. This reinforces the strength of the positive electrode layer 10.

[0050] Furthermore, the conductive fibers 3 are conductive. Therefore, the conductive fibers 3 do not impair the battery performance. This allows both an improvement in the battery capacity of the all-solid-state battery 100 and the maintenance of the strength of the positive electrode layer 10.

[0051] The plurality of conductive fibers 3 include, for example, conductive fibers 3 having a fiber diameter of 30 nm or less and a fiber length 300 times or more the fiber diameter (i.e., a fiber diameter:fiber length ratio of 1:300 or more). The fiber diameter and fiber length are measured, for example, by observation with an electron microscope.

[0052] The plurality of conductive fibers 3 may have an average fiber diameter of 30 nm or less, and an average ratio of fiber length to fiber diameter of 300 times or more.

[0053] When the fiber diameter of the conductive fibers 3 is 30 nm or less, the flexibility of the conductive fibers 3 makes it easier for the conductive fibers 3 to become entangled with the material of the positive electrode mixture layer 11, thereby effectively improving the strength of the positive electrode mixture layer 11. Furthermore, when the fiber length of the conductive fibers 3 is 300 times or more the fiber diameter, the fiber length becomes longer, making it easier for the conductive fibers 3 to become entangled with the material of the positive electrode mixture layer 11, thereby effectively improving the strength of the positive electrode mixture layer 11.

[0054] The fiber diameter is, for example, 1 nm or more. This makes the conductive fibers 3 less likely to break, effectively improving the strength of the positive electrode mixture layer 11. The ratio of the fiber length to the fiber diameter is, for example, 10,000 times or less. This improves the handleability of the conductive fibers 3.

[0055] The plurality of conductive fibers 3 include, for example, conductive fibers 3 having a fiber length of 1000 nm or more and 10000 nm or less. This allows both the strength of the positive electrode mixture layer 11 and the handleability of the conductive fibers 3 to be achieved.

[0056] The plurality of conductive fibers 3 include, for example, conductive fibers 3 having a fiber length ratio of 1 to 3 times the average particle size of the positive electrode active material 2. This allows both the strength of the positive electrode mixture layer 11 and the handleability of the conductive fibers 3 to be achieved.

[0057] Examples of materials for the conductive fibers 3 include conductive carbon materials. Examples of conductive carbon materials include carbon nanotubes and carbon nanofibers. Other examples of materials for the conductive fibers 3 include fibers in which electrical conductivity has been imparted to cellulose nanofibers. Examples of fibers in which electrical conductivity has been imparted to cellulose nanofibers include fibers in which a conductive polymer has been composited with cellulose nanofibers.

[0058] The plurality of conductive fibers 3 are uniformly distributed, for example, in the thickness direction of the positive electrode mixture layer 11. When region A in the positive electrode mixture layer 11 is located near the positive electrode bonding layer 4, region B in the center of the positive electrode mixture layer 11, and region C in the positive electrode mixture layer 11 near the surface opposite the positive electrode bonding layer 4, the difference in the content of the plurality of conductive fibers 3 per unit volume in each region is within two times. This reinforces the entire positive electrode mixture layer 11. Therefore, isolation of the positive electrode active material 2 due to cracking in the positive electrode mixture layer 11, i.e., the occurrence of unused positive electrode active material 2, can be suppressed, and a decrease in capacity of the all-solid-state battery 100 can be suppressed. Regions A, B, and C are, for example, regions obtained by dividing the positive electrode mixture layer 11 equally into three regions in the thickness direction.

[0059] For example, the material for the positive electrode mixture layer 11 may be mixed uniformly without being mixed in a solvent, and then the material may be directly coated on the positive electrode bonding layer 4 to form the positive electrode mixture layer 11, thereby allowing the plurality of conductive fibers 3 to be uniformly distributed in the thickness direction of the positive electrode mixture layer 11. This is because, since no solvent is used, the conductive fibers 3 do not float or sink due to differences in specific gravity between the positive electrode active material 2 and the solid electrolyte 1. When a conductive carbon material is used for the conductive fibers 3, the conductive fibers 3 tend to float in the solvent due to their low specific gravity.

[0060] In contrast, when the positive electrode mixture layer 11 is formed by coating the positive electrode bonding layer 4 with a slurry in which materials for the positive electrode mixture layer 11 are dispersed in a solvent and then drying the slurry, the conductive fibers 3, which have a different specific gravity from the positive electrode active material 2 and the solid electrolyte 1, float or sink during drying, and the multiple conductive fibers 3 are unevenly distributed in the positive electrode mixture layer 11. For example, when the conductive fibers 3 float due to their low specific gravity, the multiple conductive fibers 3 are distributed so that more of them are in region A and fewer are in region C. This reduces the effect of improving the strength of the positive electrode mixture layer 11 near the positive electrode bonding layer 4.

[0061] The content of the plurality of conductive fibers 3 in the positive electrode mixture layer 11 is, for example, 0.01 wt % or more and 1 wt % or less with respect to the total weight of the positive electrode mixture layer 11. When the content of the plurality of conductive fibers 3 is 1 wt % or less, a decrease in ion conductivity in the positive electrode mixture layer 11 due to the conductive fibers 3 having no ion conductivity is suppressed, and a decrease in battery capacity can be suppressed. Furthermore, when the content of the plurality of conductive fibers 3 is 0.01 wt % or more, the positive electrode mixture layer 11 can be effectively reinforced. The content of the plurality of conductive fibers 3 in the positive electrode mixture layer 11 may be 0.3 wt % or less with respect to the total weight of the positive electrode mixture layer 11. This allows the effect of reinforcing the positive electrode mixture layer 11 to be sufficiently obtained, while reducing the amount of conductive fibers 3 used, thereby reducing costs.

[0062] Furthermore, for example, some of the conductive fibers 3 are present at the interface between the positive electrode bonding layer 4 and the positive electrode mixture layer 11. That is, at least a portion of the conductive fibers 3 is located between the positive electrode bonding layer 4 and the positive electrode mixture layer 11. FIG. 3 is a schematic diagram showing a cross section near the interface between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 in this embodiment. The conductive fibers 3 present at the interface between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 include, for example, the following conductive fibers 3.

[0063] As shown in FIG. 3 , a certain conductive fiber 3 is positioned so as to connect, for example, a positive electrode contact layer 4 (specifically, a conductive agent or binder contained in the positive electrode contact layer 4), which will be described in detail later, and a positive electrode active material 2 contained in a positive electrode mixture layer 11. The conductive fiber 3 is entangled with the positive electrode contact layer 4 and the positive electrode active material 2, connecting them. The positive electrode contact layer 4 and the positive electrode active material 2 connected by the conductive fiber 3 may be adjacent to each other. The conductive fiber 3 positioned so as to connect the positive electrode contact layer 4 and the positive electrode active material 2 is an example of a second conductive fiber.

[0064] Another conductive fiber 3 is positioned so as to connect the positive electrode bonding layer 4 and the solid electrolyte 1 contained in the positive electrode mixture layer 11. The conductive fiber 3 is entangled with the positive electrode bonding layer 4 and the solid electrolyte 1, connecting them. The positive electrode bonding layer 4 and the solid electrolyte 1 connected by the conductive fiber 3 may be adjacent to each other. The conductive fiber 3 positioned so as to connect the positive electrode bonding layer 4 and the solid electrolyte 1 is an example of a third conductive fiber.

[0065] Here, the adhesion mechanism between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 will be described. As shown in Fig. 3, the positive electrode bonding layer 4 and the positive electrode mixture layer 11 are mainly bonded together by an anchor effect caused by the conductive agent and binder, which are relatively soft materials of the positive electrode bonding layer 4, plastically deforming and penetrating between the positive electrode active materials 2, between the solid electrolytes 1, and between the positive electrode active materials 2 and the solid electrolyte 1 in the positive electrode mixture layer 11.

[0066] The anchor effect is when a solid material penetrates into the gaps in the materials of the adherends (the objects to be joined) or into the irregularities on the surfaces of the adherends, creating a mechanical bond. The anchor effect is also called the fastener effect or anchoring effect.

[0067] In the present embodiment, in addition to this anchor effect, some of the elongated conductive fibers 3 are sandwiched at the interface between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 and entangled with and fixed to the positive electrode bonding layer 4, and other parts of the conductive fibers 3 are entangled with the material contained in the positive electrode mixture layer 11, thereby reinforcing the adhesion between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 and improving the adhesive strength at the interface between the positive electrode bonding layer 4 and the positive electrode mixture layer 11.

[0068] [2.1.2. Binder] The positive electrode mixture layer 11 in this embodiment is characterized by not containing a binder.

[0069] The binder is an organic material that does not have ionic or electronic conductivity and reduces the charge / discharge characteristics of the all-solid-state battery, and is an adhesive that serves to bond the materials within the positive electrode mixture layer 11 together and between the positive electrode mixture layer and other layers.

[0070] Since the positive electrode mixture layer 11 does not contain a binder, the ionic conduction and electronic conduction of the positive electrode mixture layer 11 are not inhibited, and therefore, an all-solid-state battery 100 with a large battery capacity can be obtained.

[0071] Specific examples of binders include synthetic rubbers such as butadiene rubber, isoprene rubber, styrene-butadiene rubber (SBR), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), ethylene-propylene rubber, butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, acrylic rubber, silicone rubber, fluororubber, and urethane rubber, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyimide, polyamide, polyamideimide, polyvinyl alcohol, and chlorinated polyethylene (CPE).

[0072] Since the positive electrode mixture layer 11 does not contain a binder as an adhesive, the solid electrolyte 1 is also used as an adhesive. The adhesion mechanism of the positive electrode layer 10 is as described in the section [2.1.1. Conductive fiber].

[0073] The average binder concentration per any unit volume of the positive electrode mixture layer 11 is, for example, 100 ppm or less. That is, the binder concentration of the positive electrode mixture layer 11 is, for example, 100 ppm or less throughout. The binder concentration of the positive electrode mixture layer 11 being 100 ppm or less throughout means that when the positive electrode mixture layer 11 is divided into any unit volume, the binder concentration is 100 ppm or less in every unit volume. That is, there is no portion in the positive electrode mixture layer 11 where the binder concentration is greater than 100 ppm, the binder is uniformly distributed in the positive electrode mixture layer 11, and the positive electrode mixture layer 11 is substantially free of binder throughout. In this case, when the binder concentration is 100 ppm or less throughout the positive electrode mixture layer 11, the positive electrode mixture layer 11 is substantially free of binder, and the ionic conduction and electronic conduction of the positive electrode mixture layer 11 are particularly unlikely to be inhibited. In this specification, the term "concentration" refers to a concentration based on weight unless otherwise specified.

[0074] The method for measuring the binder concentration is not particularly limited, and examples of the method for measuring the binder concentration include gas chromatography and mass variation method.

[0075] 2.1.3. Solvents The concentration of the solvent (specifically, organic solvent) contained in the positive electrode mixture layer 11 according to this embodiment is 50 ppm or less, that is, the positive electrode mixture layer 11 does not substantially contain any solvent.

[0076] Since the positive electrode mixture layer 11 does not contain a binder, the ionic conduction and electronic conduction of the positive electrode mixture layer 11 are not inhibited, and therefore, an all-solid-state battery 100 with a large battery capacity can be obtained.

[0077] The method for measuring the concentration of the solvent is not particularly limited, and examples thereof include gas chromatography and mass variation method.

[0078] Examples of organic solvents include non-polar organic solvents, polar organic solvents, and combinations thereof. Examples of non-polar organic solvents include heptane, xylene, toluene, and combinations thereof. Examples of polar organic solvents include tertiary amine solvents, ether solvents, thiol solvents, ester solvents, and combinations thereof. Examples of tertiary amine solvents include triethylamine, tributylamine, and triamylamine. Examples of ether solvents include tetrahydrofuran and cyclopentyl methyl ether. Examples of thiol solvents include ethane mercaptan. Examples of ester solvents include butyl butyrate, ethyl acetate, and butyl acetate, and combinations thereof.

[0079] The organic solvent used to prepare the positive electrode mixture slurry may be, for example, a hydrocarbon organic solvent such as heptane, toluene, or hexane, and the hydrocarbon organic solvent is dehydrated to reduce its water content.

[0080] [2.1.4. Positive electrode active material] Next, the positive electrode active material 2 in this embodiment will be described.

[0081] The positive electrode active material 2 is a material in which metal ions such as lithium (Li) are inserted into or extracted from the crystal structure at a higher potential than the negative electrode layer, and oxidation or reduction occurs along with the insertion or extraction of the metal ions such as lithium. The type of the positive electrode active material 2 is appropriately selected depending on the type of all-solid-state battery, and examples thereof include oxide active materials and sulfide active materials.

[0082] In this embodiment, for example, an oxide active material (lithium-containing transition metal oxide) is used as the positive electrode active material 2. Examples of oxide active materials include LiCoO2, LiNiO2, LiMn2O4, LiCoPO4, LiNiPO4, LiFePO4, and LiMnPO4, as well as compounds obtained by substituting one or two different elements for the transition metals in these compounds. Examples of compounds obtained by substituting one or two different elements for the transition metals in the above compounds include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.5 Mn 1.5 Known materials such as O2 can be used. The positive electrode active material 2 may be used alone or in combination of two or more.

[0083] The shape of the positive electrode active material 2 may be, for example, a particulate shape or a thin film shape. The positive electrode active material 2 is, for example, composed of a plurality of particles. When the positive electrode active material 2 is composed of a plurality of particles, the average particle diameter (D 50 ) is, for example, in the range of 50 nm to 50 μm, and may be in the range of 1 μm to 15 μm. By setting the average particle size of the positive electrode active material to 50 nm or more, handling is likely to be improved, while by setting the average particle size to 50 μm or less, a flat positive electrode layer 10 is likely to be obtained. Note that the "average particle size" in this specification refers to the volume-based average diameter measured by a laser diffraction and scattering particle size distribution analyzer.

[0084] The ratio of the solid electrolyte 1 to the positive electrode active material 2 in the positive electrode mixture layer 11 is not particularly limited, but may be, for example, in the range of 50:50 to 5:95 by weight, or may be in the range of 30:70 to 5:95 by weight. By keeping the ratio within this range, both ionic conduction paths and electronic conduction paths are easily secured in the positive electrode layer 10.

[0085] The surface of the positive electrode active material 2 may be covered with a coating layer. This is because it is possible to suppress the reaction between the positive electrode active material 2 (e.g., an oxide active material) and the solid electrolyte 1 (e.g., a sulfide-based solid electrolyte). Examples of materials for the coating layer include Li-ion conductive oxides such as LiNbO3, Li3PO4, and LiPON. The average thickness of the coating layer is, for example, in the range of 1 nm to 20 nm, and may be in the range of 1 nm to 10 nm.

[0086] [2.1.5. Solid electrolyte] Next, the solid electrolyte 1 in this embodiment will be described.

[0087] The solid electrolyte 1 may be appropriately selected depending on the type of conductive ion (for example, lithium ions), and can be broadly divided into sulfide-based solid electrolytes and oxide-based solid electrolytes, for example.

[0088] The type of sulfide-based solid electrolyte in this embodiment is not particularly limited. Examples of sulfide-based solid electrolytes include Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, and Li2S-P2S5. In particular, sulfide-based solid electrolytes containing Li, P, and S are preferred due to their excellent lithium ion conductivity. The sulfide-based solid electrolyte may be used alone or in combination with two or more. The sulfide-based solid electrolyte may be crystalline, amorphous, or glass ceramic. The term "Li2S-P2S5" refers to a sulfide-based solid electrolyte formed using a raw material composition containing Li2S and P2S5, and the same applies to other terms.

[0089] In this embodiment, one form of the sulfide-based solid electrolyte is a sulfide glass ceramic containing Li2S and P2S5, and the ratio of Li2S to P2S5, expressed as Li2S / P2S5 molar ratio in molar terms, is preferably in the range of 2.3 to 4, more preferably 3 to 4. The reason why this molar ratio range is preferable is that it allows for a crystal structure with high ion conductivity to be obtained while maintaining the lithium concentration that affects the battery characteristics.

[0090] Next, the oxide-based solid electrolyte in this embodiment will be described. The type of oxide-based solid electrolyte is not particularly limited, but examples thereof include LiPON, Li3PO4, Li2SiO2, Li2SiO4, Li 0.5 La 0.5 TiO3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, La 0.51 Li 0.34 TiO 0.74 , Li 1.5 Al 0.5 Ge 1.5 (PO4)3, etc. The oxide-based solid electrolyte may be used alone or in combination of two or more.

[0091] The shape of the solid electrolyte 1 in this embodiment may be, for example, a particle shape such as a spherical shape or an oval spherical shape, or a thin film shape. The solid electrolyte 1 is, for example, composed of a plurality of particles. When the solid electrolyte 1 is composed of a plurality of particles, the average particle diameter (D 50 ) is not particularly limited, but is, for example, 40 μm or less, or may be 20 μm or less, or may be 10 μm or less, since this facilitates improving the filling rate in the positive electrode layer. On the other hand, the average particle size of the solid electrolyte 1 is, for example, 0.001 μm or more, or may be 0.01 μm or more. The average particle size of the solid electrolyte 1 can be determined, for example, by image analysis using a particle size distribution analyzer or a scanning electron microscope (SEM).

[0092] [2.2. Positive electrode contact layer] Next, the positive electrode bonding layer 4 in this embodiment will be described.

[0093] The role of the positive electrode contact layer 4 is to connect the positive electrode current collector 6 and the positive electrode mixture layer 11 via the positive electrode contact layer 4. The positive electrode contact layer 4 contains a conductive agent as a main component and may also contain a binder. In addition, the positive electrode contact layer 4 does not contain, for example, the positive electrode active material 2 or the solid electrolyte 1.

[0094] In the present embodiment, since the positive electrode mixture layer 11 does not contain a binder, if the positive electrode layer 10 does not have the positive electrode bonding layer 4, the adhesive strength between the positive electrode current collector 6 and the positive electrode mixture layer 11 is weak, and peeling at the interface is likely to occur. Since the interface between the positive electrode current collector 6 and the positive electrode mixture layer 11 requires stronger adhesive strength, the positive electrode bonding layer 4 is used to reinforce the adhesive strength.

[0095] The bonding mechanism between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 is as described in the section [2.1.1. Conductive fibers].

[0096] The conductive agents contained in the positive electrode contact layer 4 are bonded together via the binder contained in the positive electrode contact layer 4, thereby maintaining the shape.

[0097] The positive electrode contact layer 4 is also bonded to the positive electrode current collector 6 via the binder contained in the positive electrode contact layer 4.

[0098] The positive electrode mixture layer 11 and the positive electrode current collector 6 conduct electrons via the positive electrode contact layer 4. In an all-solid-state battery, important characteristics for maintaining battery capacity are the ionic conductivity and electronic conductivity in the positive electrode mixture layer 11. Even if the electronic conductivity of the positive electrode contact layer 4 decreases due to the inclusion of a binder, the main component is a conductive agent, and the electronic conductivity is sufficient to maintain charge / discharge characteristics, so there is substantially no effect on the battery capacity of the all-solid-state battery 100.

[0099] Examples of conductive agents include conductive carbon materials such as acetylene black, Ketjen Black (registered trademark), carbon black, graphite, and carbon fiber. One type of conductive agent may be used, or two or more types may be used in combination. As described above, for example, a non-metallic conductive agent is used as the conductive agent. By not using a metal as the conductive agent, problems such as changes in the battery potential and metal corrosion can be prevented. Furthermore, the use of a relatively soft non-metallic conductive agent makes it easier for the above-mentioned anchoring effect to be exhibited.

[0100] Specific examples of binders include synthetic rubbers such as butadiene rubber, isoprene rubber, styrene-butadiene rubber (SBR), styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), ethylene-propylene rubber, butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, acrylic rubber, silicone rubber, fluororubber, and urethane rubber, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyimide, polyamide, polyamideimide, polyvinyl alcohol, and chlorinated polyethylene (CPE).

[0101] The weight of the positive electrode bonding layer 4 is, for example, 0.1 g / m 2 More than 10g / m 2 The weight of the positive electrode bonding layer 4 is 0.1 g / m or less. 2 By setting the weight of the positive electrode bonding layer 4 to the positive electrode mixture layer 11 or more, an anchor effect is easily exerted in the bonding between the positive electrode bonding layer 4 and the positive electrode mixture layer 11, and the adhesive strength is increased, thereby suppressing interfacial peeling between the positive electrode bonding layer 4 and the positive electrode mixture layer 11. In addition, when the weight of the positive electrode bonding layer 4 is set to 10 g / m 2 By doing so, it is possible to obtain the effect of improving the adhesive strength between the positive electrode bonding layer 4 and the positive electrode mixture layer 11, while avoiding an increase in the amount of the positive electrode bonding layer 4, thereby reducing costs.

[0102] The weight of the positive electrode bonding layer 4 is 0.3 g / m 2 More than 3g / m2 It may be less than 0.3g / m 2 By setting the thickness to 3 g / m or more, the adhesive strength between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 becomes stronger. 2 Even at this temperature, sufficient adhesive strength can be maintained.

[0103] Here, the basis weight in the present disclosure refers to the weight per unit area of ​​the positive electrode bonding layer 4 in a plan view on the main surface of the positive electrode current collector 6 on which the positive electrode bonding layer 4 is formed.

[0104] The thickness of the positive electrode bonding layer 4 is, for example, in the range of 1 μm to 10 μm, and may be 2 μm to 6 μm. By making the thickness of the positive electrode bonding layer 4 1 μm or more, an anchor effect is easily exerted in the bonding between the positive electrode bonding layer 4 and the positive electrode mixture layer 11, and the adhesive strength is strengthened, thereby making it possible to suppress interfacial peeling between the positive electrode bonding layer 4 and the positive electrode mixture layer 11. By making the thickness of the positive electrode bonding layer 4 10 μm or less, it is possible to improve the adhesive strength between the positive electrode bonding layer 4 and the positive electrode mixture layer 11 while avoiding an increase in the amount of the positive electrode bonding layer 4, thereby reducing costs.

[0105] The amount of binder contained in the positive electrode contact layer 4 is, for example, 0.1 wt % or more and 10 wt % or less. By making the amount of binder contained in the positive electrode contact layer 4 0.1 wt % or more, the positive electrode contact layer 4 is easily adhered to the positive electrode mixture layer 11 and the positive electrode current collector 6, and peeling at this interface can be suppressed. By making the amount of binder contained in the positive electrode contact layer 4 10 wt % or less, the electronic conductivity of the positive electrode contact layer 4 is less likely to decrease, and the charge / discharge characteristics of the all-solid-state battery are likely to improve.

[0106] [2.3. Positive electrode current collector] The positive electrode layer 10 in this embodiment includes a positive electrode current collector 6 made of, for example, a metal foil. The positive electrode current collector 6 is, for example, a foil, plate, mesh, or the like made of aluminum, gold, platinum, zinc, copper, SUS, nickel, tin, titanium, or an alloy of two or more of these metals.

[0107] The thickness, shape, etc. of the positive electrode current collector 6 may be appropriately selected depending on the application of the all-solid-state battery.

[0108] [2.4. Method of manufacturing the positive electrode layer] A method for manufacturing the positive electrode layer 10 in this embodiment will be described.

[0109] The manufacturing method of the positive electrode layer 10 includes, for example, a positive electrode layer forming step. The positive electrode layer forming step is a step of forming the positive electrode layer 10 having a positive electrode mixture layer 11 in which the organic solvent concentration is 50 ppm or less and the binder concentration is 100 ppm or less. The positive electrode layer forming step includes a positive electrode bonding layer forming step, a positive electrode mixture layer applying step, and a positive electrode layer integrating step. In the positive electrode bonding layer forming step, a positive electrode bonding layer 4 containing at least a conductive agent is formed on at least one surface of a positive electrode current collector 6. In the positive electrode mixture layer applying step, a positive electrode mixture powder containing at least a solid electrolyte 1, a positive electrode active material 2, and a plurality of conductive fibers 3 is applied to the surface on which the positive electrode bonding layer 4 is formed. In the positive electrode layer integrating step, the positive electrode mixture powder is pressed to form the positive electrode layer 10, which is an integrated product of the positive electrode current collector 6, the positive electrode bonding layer 4, and the positive electrode mixture layer 11.

[0110] The positive electrode contact layer forming step is a step of forming the positive electrode contact layer 4 on the positive electrode current collector 6. For example, the positive electrode contact layer 4 is formed by applying a paste containing a conductive agent and a binder onto the positive electrode current collector 6 and drying it.

[0111] Next, in the positive electrode mixture layer application step, first, the solid electrolyte 1, the positive electrode active material 2, and a plurality of conductive fibers 3 are mixed and dispersed to prepare a solvent-free positive electrode mixture powder.

[0112] Also, a positive electrode current collector 6 on which the positive electrode bonding layer 4 formed in the positive electrode bonding layer forming step is formed is prepared.

[0113] The prepared positive electrode mixture powder is then applied onto the positive electrode bonding layer 4. The positive electrode mixture powder is characterized by not containing a binder, and the binder concentration is 100 ppm or less.

[0114] The method for applying the positive electrode mixture powder onto the positive electrode bonding layer 4 includes applying the positive electrode mixture powder that does not contain an organic solvent using a vibration feeder, table feeder, or screw feeder, or electrostatic application.

[0115] Furthermore, by using the above manufacturing method, no organic solvent is used, so the concentration of the organic solvent in the positive electrode mixture layer 11 is 50 ppm or less, and deterioration of the solid electrolyte 1 due to the organic solvent can be suppressed.

[0116] Next, in the positive electrode layer integration process, the positive electrode mixture powder is pressed together with the positive electrode current collector 6 and the positive electrode bonding layer 4 from above and below in the stacking direction to produce a positive electrode layer 10, which is an integrated body consisting of the positive electrode mixture layer 11, the positive electrode bonding layer 4, and the positive electrode current collector 6. This pressing process allows the solid electrolyte 1 to be used as an adhesive, even though the positive electrode mixture layer 11 does not contain a binder. Furthermore, the multiple elongated conductive fibers 3 act as reinforcing materials, allowing the positive electrode mixture powder to be handled without falling off from the positive electrode layer 10 during the subsequent manufacturing process of the all-solid-state battery 100. This also improves the strength of the positive electrode layer 10 as part of the all-solid-state battery 100. The pressing in the positive electrode layer integration process may be performed by hot pressing. This allows for a more dense positive electrode mixture layer 11 to be obtained.

[0117] There are two mechanisms of adhesion by the solid electrolyte 1. (1) The solid electrolyte 1 and the positive electrode active material 2 in the positive electrode mixture layer 11 are bonded together by an anchor effect caused by the solid electrolyte 1 penetrating into the positive electrode active material 2. (2) The solid electrolytes 1 in the positive electrode mixture layer 11 adhere to each other, and are bonded together by intermolecular forces or by an anchor effect caused by penetrating into each other. Furthermore, the multiple long and thin conductive fibers 3 are fixed to the positive electrode active material 2 and the solid electrolyte 1 in an entangled state, and the multiple conductive fibers 3 act as reinforcing materials.

[0118] The positive electrode bonding layer 4 and the positive electrode mixture layer 11 are bonded together by an anchor effect caused by the positive electrode bonding layer 4 plastically deforming and biting into the spaces between the positive electrode active materials 2, between the solid electrolytes 1, and between the positive electrode active materials 2 and the solid electrolyte 1 in the positive electrode mixture layer 11. Furthermore, the long, thin conductive fibers 3 are sandwiched and fixed at the interface between the positive electrode bonding layer 4 and the positive electrode mixture layer 11, and are also entangled with the material contained in the positive electrode mixture layer 11, thereby reinforcing the bond between the positive electrode bonding layer 4 and the positive electrode mixture layer 11.

[0119] The pressing pressure is, for example, 10 MPa or more and 2000 MPa or less. By setting the pressing pressure to 10 MPa or more, sufficient adhesive strength can be obtained, and the problem of the solid electrolyte 1 and the positive electrode active material 2 falling off from the positive electrode mixture layer 11 during the subsequent process can be suppressed. Furthermore, by setting the pressing pressure to 2000 MPa or less, the applied pressure is not too high, and the problem of the positive electrode current collector 6 breaking can be suppressed.

[0120] From the viewpoint of increasing the packing rate of the positive electrode mixture layer 11, the pressing pressure may be 400 MPa or more and 2000 MPa or less.

[0121] Increasing the filling rate of the positive electrode mixture layer 11 can improve the ionic conductivity of lithium ions and the like and the electronic conductivity of the positive electrode mixture layer 11, thereby obtaining good battery characteristics. The filling rate refers to the ratio of the volume of all materials occupying an object to the apparent volume of the object. For example, the filling rate of the positive electrode mixture layer 11 refers to the ratio of the volume of all materials constituting the positive electrode mixture layer 11 to the apparent volume of the positive electrode mixture layer 11.

[0122] The pressing temperature may be set appropriately depending on the material contained in the positive electrode mixture layer 11, and is, for example, 20°C or higher and 300°C or lower. A pressing temperature of 20°C or higher can soften the contained solid electrolyte 1 and improve the density of the positive electrode mixture layer 11. Furthermore, a pressing temperature of 300°C or lower can prevent excessive sintering due to overheating, and can sinter the layers in a subsequent step of joining the layers.

[0123] The pressing method in the above-described manufacturing method is not particularly limited, and any known pressing method may be employed.

[0124] By using the above-described method, a binder that inhibits battery capacity is not used to increase battery capacity, and even when the amount of solid electrolyte 1 that acts as an adhesive is reduced, the positive electrode mixture layer 11 contains a plurality of long, thin conductive fibers 3 that do not inhibit battery capacity, thereby reinforcing the positive electrode layer 10. This makes it possible to achieve both an improvement in battery capacity and maintaining the strength of the positive electrode layer 10.

[0125] Furthermore, by pressing, the solid electrolyte 1 can be used as an adhesive material, and the conductive fibers 3 can be used as a reinforcing material, so that the positive electrode active material 2 and the solid electrolyte 1 can be prevented from falling off from the positive electrode mixture layer 11, and an all-solid-state battery 100 having a good battery capacity can be obtained.

[0126] Furthermore, since no organic solvent is used in the manufacturing process of the positive electrode mixture layer 11, the positive electrode mixture layer 11 does not substantially contain any organic solvent, and therefore, there is no deterioration of the positive electrode mixture layer 11 due to the organic solvent, and an all-solid-state battery 100 having a good battery capacity can be manufactured.

[0127] [3. Negative electrode layer] Although the use of a plurality of conductive fibers 3 in the positive electrode layer 10 has been described above, the same effect can be achieved by using a plurality of conductive fibers 3 in the negative electrode layer 20. That is, the negative electrode layer 20 can also be described by replacing the positive electrode active material 2 with the negative electrode active material in the above description of the configuration and manufacturing method of each layer of the positive electrode layer 10.

[0128] For example, the negative electrode bonding layer 5 is made of the same material as the positive electrode bonding layer 4, and the negative electrode current collector 7 is made of the same material as the positive electrode current collector. The differences between the positive electrode mixture layer 11 and the negative electrode mixture layer 21 will be described below. Examples of negative electrode active materials include metals that easily alloy with lithium, such as lithium, indium, tin, and silicon, carbon materials such as hard carbon and graphite, and Li4Ti5O 12 , SiOx Known materials such as oxide active materials, etc., can be used. Furthermore, as the negative electrode active material, a composite in which the above-mentioned negative electrode active materials are appropriately mixed can also be used.

[0129] The ratio of the solid electrolyte to the negative electrode active material is, for example, in the range of 60:40 to 5:95 by weight, and may be in the range of 40:60 to 5:95 by weight, which makes it easier to ensure both ionic and electronic conduction paths within the negative electrode layer.

[0130] [4. Solid electrolyte layer] Next, the solid electrolyte layer 30 will be described. The solid electrolyte layer 30 in this embodiment includes a solid electrolyte having at least lithium ion conductivity. The solid electrolyte layer 30 may include a binder, but may not substantially include a binder. When the solid electrolyte layer 30 does not include a binder, the solid electrolyte is used as an adhesive. The solid electrolytes are bonded together by sintering the solid electrolyte.

[0131] The solid electrolyte contained in the solid electrolyte layer 30 can be the same as the solid electrolyte 1 described above.

[0132] The solid electrolyte layer 30 is manufactured, for example, by forming a film from the material of the solid electrolyte layer 30 and pressing the formed material of the solid electrolyte layer 30. The solid electrolyte layer 30 may be formed as a film on at least one of the positive electrode mixture layer 11 and the negative electrode mixture layer 21, or may be formed as a film on a substrate and then laminated on at least one of the positive electrode mixture layer 11 and the negative electrode mixture layer 21.

[0133] (Other embodiments) The all-solid-state battery and each layer of the all-solid-state battery according to the present disclosure have been described above based on embodiments, but the present disclosure is not limited to the above embodiments. The above embodiments are merely examples, and anything that has substantially the same configuration as the technical idea and exhibits similar effects within the scope of the claims of the present disclosure is included within the technical scope of the present disclosure. Furthermore, various modifications that a person skilled in the art could conceive of to the embodiments and other forms constructed by combining some of the components of the embodiments are also included within the scope of the present disclosure, as long as they do not deviate from the gist of the present disclosure.

[0134] For example, in the above embodiment, the ions conducted in the all-solid-state battery 100 are lithium ions, but this is not limiting. The ions conducted in the all-solid-state battery 100 may be ions other than lithium ions, such as sodium ions, magnesium ions, potassium ions, calcium ions, or copper ions.

[0135] Furthermore, for example, in the all-solid-state battery 100, multiple conductive fibers 3 do not have to be used in both the positive electrode layer 10 and the negative electrode layer 20, and multiple conductive fibers 3 may be used in either the positive electrode layer 10 or the negative electrode layer 20.

[0136] Furthermore, for example, in the all-solid-state battery 100, the positive electrode layer 10 includes the positive electrode bonding layer 4, and the negative electrode layer 20 includes the negative electrode bonding layer 5, but this is not limited thereto. For example, the all-solid-state battery 100 may have a configuration including, instead of the positive electrode layer 10, a positive electrode layer composed of a positive electrode mixture layer 11 containing a binder and not containing a plurality of conductive fibers 3, and a positive electrode current collector 6, or a configuration including, instead of the negative electrode layer 20, a negative electrode layer composed of a negative electrode mixture layer 21 containing a binder and not containing a plurality of conductive fibers 3, and a negative electrode current collector 7. [Industrial Applicability]

[0137] The positive electrode layer and negative electrode layer for all-solid-state batteries according to the present disclosure are expected to be applied to a variety of batteries, such as power sources for portable electronic devices and automotive batteries. [Explanation of symbols]

[0138] 1 Solid electrolyte 2 Cathode active material 3. Conductive fibers 4 Positive electrode junction layer 5 Negative electrode bonding layer 6 Positive electrode current collector 7 Negative electrode current collector 10 Positive electrode layer 11 Positive electrode mixture layer 20 negative electrode layer 21 negative electrode mixture layer 30 Solid electrolyte layer 100 solid state battery

Claims

1. An electrode layer for use in an all-solid-state battery, an electrode current collector; an electrode contact layer formed on the electrode current collector, the electrode contact layer including at least a conductive agent; an electrode mixture layer formed on the electrode contact layer, the electrode mixture layer including at least an electrode active material formed of a plurality of particles, a solid electrolyte having ion conductivity, and a plurality of conductive fibers; the plurality of conductive fibers include first conductive fibers positioned so as to connect adjacent particles of the electrode active material, the concentration of the binder contained in the electrode mixture layer is 100 ppm or less, and the concentration of the solvent contained in the electrode mixture layer is 50 ppm or less; some of the plurality of conductive fibers are present at the interface between the electrode junction layer and the electrode mixture layer; The part of the conductive fibers is second conductive fibers positioned so as to connect the electrode contact layer and the electrode active material; and a third conductive fiber positioned so as to connect the electrode contact layer and the solid electrolyte. electrode layer.

2. The first conductive fibers pass through the solid electrolyte between adjacent particles of the electrode active material. The electrode layer according to claim 1 .

3. The electrode layer is a positive electrode layer or a negative electrode layer. The electrode layer according to claim 1 or 2.

4. The plurality of conductive fibers include conductive fibers having a fiber diameter of 30 nm or less and a fiber length of 300 times or more relative to the fiber diameter. The electrode layer according to any one of claims 1 to 3.

5. The content of the plurality of conductive fibers in the electrode mixture layer is 1 wt % or less with respect to the total weight of the electrode mixture layer. The electrode layer according to any one of claims 1 to 4.

6. The electrode layer according to any one of claims 1 to 5 is provided. All-solid-state battery.

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