Positive electrode material for all-solid-state lithium-ion battery, positive electrode and method for producing the same, and all-solid-state lithium-ion battery

Abstract

To provide a novel positive electrode material capable of imparting excellent battery capacity and cycle stability to an all-solid-state lithium ion battery, a positive electrode having the positive electrode material, and a method for manufacturing the same.SOLUTION: The present invention relates to a positive electrode material for an all-solid-state lithium ion battery, the positive electrode material includes at least an electrolyte particle, the electrolyte particle includes a polyether block amide copolymer and a lithium salt. The positive electrode material according to the present invention can provide the all-solid-state lithium ion battery with excellent battery capacity and cycle stability.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a cathode material for an all-solid-state lithium-ion battery, a cathode, a method for manufacturing the same, and an all-solid-state lithium-ion battery.

Background Art

[0002] All-solid-state lithium-ion batteries are highly expected as the most promising next-generation energy storage devices. Since all-solid-state lithium-ion batteries do not contain a flammable organic liquid electrolyte, they are considered to be less likely to cause safety problems, and thus are regarded as the ultimate solution to safety problems.

[0003] On the other hand, current various all-solid-state lithium-ion batteries have a large interfacial resistance between the electrode and the electrolyte, which causes an increase in the migration resistance of lithium ions between the electrodes. In addition, since the increase in the active material loading amount (load fluctuation tolerance) on the cathode (cathode) side is restricted, there is a problem that it is difficult to increase the output as a battery. Therefore, there is room for improvement in current all-solid-state lithium-ion batteries, and active research and development are being carried out to achieve better battery performance. For example, Non-Patent Document 1 discloses a technique in which a crosslinked polymer containing a pendant molecule bonded to a polymer backbone is applied to an all-solid-state lithium-ion battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, all-solid-state lithium-ion batteries with large battery capacity and stable battery capacity even with an increased number of cycles have been demanded. Therefore, developing a cathode with high load resistance that has both excellent ionic conductivity and electronic conductivity is a major step forward in the practical application of all-solid-state lithium-ion batteries, and developing new cathode materials occupies an extremely important position in this field.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a novel cathode material capable of imparting excellent battery capacity and cycle stability to an all-solid-state lithium-ion battery, a cathode having the cathode material, and a method for manufacturing the same.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using electrolyte particles containing a polyether block amide copolymer and a lithium salt as essential components, and have completed the present invention.

[0008] That is, the present invention includes, for example, the subject matters described in the following items. Item 1 A cathode material for an all-solid-state lithium-ion battery, At least containing electrolyte particles, The electrolyte particles contain a polyether block amide copolymer and a lithium salt, and the cathode material for an all-solid-state lithium-ion battery. Item 2 The polyether block amide copolymer has a polyether moiety and a polyamide moiety in its structural unit, and the cathode material according to Item 1. Item 3 The structural unit of the polyether block amide copolymer is represented by the following general formula (1) -(CO-PA-COO-PE-O)- (1) (Here, PA represents a polyamide moiety, and PE represents a polyether moiety) The cathode material according to Item 2, which is represented by. Item 4 The positive electrode material according to any one of claims 1 to 3, further comprising a positive electrode active material, a binder, and a conductive assistant. Claim 5 A positive electrode for an all-solid-state lithium-ion battery, comprising the positive electrode material according to any one of claims 1 to 4. Claim 6 An all-solid-state lithium-ion battery comprising the positive electrode according to claim 5. Claim 7 A method for manufacturing a positive electrode for an all-solid-state lithium-ion battery according to claim 5, A step of applying a slurry containing the electrolyte particles and a solvent onto a current collector to form a coating film, A step of obtaining the positive electrode material by thermally pressing the coating film A method for manufacturing a positive electrode for an all-solid-state lithium-ion battery, comprising:

Advantages of the Invention

[0009] The positive electrode material for an all-solid-state lithium-ion battery of the present invention can impart excellent battery capacity and cycle stability to the all-solid-state lithium-ion battery.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail. In this specification, expressions such as "containing" and "comprising" include the concepts of "containing", "comprising", "substantially consisting of", and "consisting only of".

[0012] 1. Cathode material for all-solid-state lithium-ion battery The positive electrode material for all-solid-state lithium-ion batteries of the present invention (hereinafter, may be abbreviated as "positive electrode material") at least contains electrolyte particles, and the electrolyte particles contain a polyether block amide copolymer and a lithium salt.

[0013] By including the electrolyte particles, the positive electrode material of the present invention can impart excellent battery capacity and cycle stability to all-solid-state lithium-ion batteries. Therefore, the positive electrode material of the present invention can be suitably used as a material for forming a positive electrode incorporated in an all-solid-state lithium-ion battery.

[0014] (Electrolyte particles) The electrolyte particles contain at least a polyether block amide copolymer and a lithium salt, and are materials formed in a particulate state. However, since the positive electrode material is heat-pressed as described later, the electrolyte particles can be in a form where they are fused together with the positive electrode active material in the positive electrode.

[0015] The type of the lithium salt is not particularly limited, and for example, known lithium salts used in electrolytes of all-solid-state lithium-ion batteries can be widely cited.

[0016] Examples of the lithium salt include LiPF6 (lithium hexafluorophosphate), LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOB), LiF, LiCl, LiBr, LiI, Li3N, Li3P, Li2S, LiNO3, and the like. The lithium salt contained in the electrolyte particles can be one kind alone or two or more kinds.

[0017] The lithium salt can be produced by a known method and can also be obtained from commercially available products or the like.

[0018] Since the electrolyte particles contain a lithium salt, the ionic conductivity of lithium ions is improved, so that excellent battery capacity and cycle stability can be imparted to the all-solid-state lithium-ion battery.

[0019] The polyether block amide copolymer is a main component constituting the electrolyte particles. The type of the polyether block amide copolymer is not particularly limited, and for example, known polyether block amide copolymers can also be widely applied in the present invention.

[0020] The polyether block amide copolymer can have a polyether moiety (also referred to as a polyether segment) and a polyamide moiety (also referred to as a polyamide segment) in the structural unit.

[0021] The type of the polyether segment is not particularly limited, and for example, known polyethers can be widely applied. Examples of the polyether segment include polyalkylene oxides, specifically polyethylene oxide, polymethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polytrimethylene oxide, and the like. The number average molecular weight of the polyether segment is not particularly limited.

[0022] The type of the polyamide segment is not particularly limited, and for example, known polyamides can be widely applied. Examples of the polyamide segment include nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, and the like. The number average molecular weight of the polyamide segment is not particularly limited.

[0023] The structural unit of the polyether block amide copolymer preferably has a structure represented by the following formula (1) -(CO-PA-COO-PE-O)- (1) Preferably, it has a structure represented by.

[0024] In formula (1), PA represents the polyamide moiety. That is, PA in formula (1) is synonymous with the polyamide segment. In formula (1), PE represents the polyether moiety. That is, PE in formula (1) is synonymous with the polyether segment.

[0025] Examples of the structural unit represented by formula (1) include a structural unit in which PA is nylon 12 and PE is polytetramethylene oxide. In this case, the positive electrode material of the present invention can impart particularly excellent battery capacity and cycle stability to an all-solid-state lithium-ion battery.

[0026] When the polyether block amide copolymer includes a structural unit represented by formula (1), such a polyether block amide copolymer is advantageous in that its structure includes a hard polyamide (PA) block and a soft polyether (PE) block that enable excellent dynamic properties. Although not necessarily wishing to be construed in a limiting sense, it is presumed that both the amide group and the ether group of the polyether block amide copolymer can provide rich chemical properties for interacting with the lithium salt.

[0027] The number average molecular weight of the polyether block amide copolymer is not particularly limited, and for example, it can be in the same range as the number average molecular weight of the polymer materials used in conventional all-solid-state lithium-ion batteries.

[0028] The polyether block amide copolymer contained in the electrolyte particles can be a single type or two or more types. When the electrolyte particles contain two or more polyether block amide copolymers, for example, two or more polyether block amide copolymers of different types such as PA and PE may be contained in the electrolyte particles.

[0029] The method for producing the polyether block amide copolymer is not particularly limited. For example, the polyether block amide copolymer can be produced by a known production method. Also, the polyether block amide copolymer can be obtained from commercially available products, etc. For example, Pebax (registered trademark) elastomers of Arkema can be mentioned. Specifically, "PEBA2533", "PEBAX", etc. are exemplified.

[0030] The electrolyte particles can contain other polymer compounds other than the polyether block amide copolymer and can also contain electrolytes other than the lithium salt as long as the effects of the present invention are not inhibited. Also, the electrolyte particles may contain other components as long as the effects of the present invention are not inhibited. The electrolyte particles may consist only of the polyether block amide copolymer and the lithium salt.

[0031] In the electrolyte particles, the content ratios of the polyether block amide copolymer and the lithium salt are not particularly limited. For example, the content ratio of the lithium salt contained in the electrolyte particles is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 30% by mass.

[0032] The shape of the electrolyte particles is not particularly limited, and examples include spherical, elliptical, and irregular shapes other than spheres and ellipses. The size of the electrolyte particles is also not particularly limited, and for example, it can be 1 to 50 μm, preferably 5 to 10 μm. The size of the electrolyte particles referred to here means the value obtained by randomly selecting 50 particles by direct observation of the electrode with a scanning electron microscope and measuring and arithmetically averaging their equivalent circle diameters.

[0033] The method for manufacturing the electrolyte particles is not particularly limited, and for example, known particle manufacturing methods can be widely adopted. For example, by mixing the polyether block amide copolymer, the lithium salt, and the solvent, a gelled product can be obtained, and then by pulverizing this gelled product, electrolyte particles can be obtained. The solvent contained in the electrolyte particles obtained by pulverization can be dried by an appropriate method. Alternatively, the solvent contained in the gelled product may be dried by an appropriate method and then pulverized.

[0034] The solvents used in manufacturing the electrolyte particles can include various organic solvents. Examples of organic solvents include chlorinated hydrocarbons such as chloroform and 1,2-dichloroethane; ether compounds such as diethyl ether and tetrahydrofuran; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; ketone compounds such as acetone and methyl ethyl ketone; ester compounds such as vinyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol, and t-butanol; formamides such as N,N-dimethylformamide and N,N-dimethylacetamide; pyrrolidones such as 2-pyrrolidone and N-methylpyrrolidone; and dimethyl sulfoxide.

[0035] The method of mixing a polyether block amide copolymer, a lithium salt, and a solvent is not particularly limited, and they may be mixed in predetermined compounding amounts. In this mixing, it is also possible to appropriately heat the mixture in consideration of the boiling point of the solvent to be used, etc. For example, the mixing can be carried out at 40 to 80°C. The method of pulverizing the gelled product is not particularly limited, and for example, pulverization can be carried out using known pulverization means.

[0036] (Positive electrode material) In addition to the aforementioned electrolyte particles, the positive electrode material of the present invention can further contain a positive electrode active material, a binder, and a conductive aid. Examples of the positive electrode active material, the binder, and the conductive aid can widely include materials used for forming a positive electrode (cathode) of a known all-solid-state lithium ion battery.

[0037] Examples of the positive electrode active material include various lithium-based positive electrode active materials. Examples of the positive electrode active material include LiFePO4, LiCoO2, LiNi x Mn y Co z O2 (0.3 ≦ x ≦ 0.95, 0.025 ≦ y ≦ 0.4, 0.025 ≦ y ≦ 0.4), LiNi 1-y-z Co y Al z O2 (0.05 ≦ y ≦ 0.15, 0 < z ≦ 0.05), LiMn2O4, LiMPO4 (M = Co, Ni), Li2FePO4F, V2O5, Li X V3O8 (1.5 ≦ x ≦ 5.5), Li 1-X VOPO4 (0.5 ≦ x ≦ 0.92), Li4Ti5O 12 , LiFeMO4 (M = Mn, Si), S, Se, SeS2, Na3V2(PO4)3, Na2MnP2O7, NaFePO4, Na3MnZr(PO4)3, etc.

[0038] As the binder, known materials used in all-solid-state lithium ion batteries can be used. For example, various polymers such as polyvinylidene fluoride (PVDF) and polyethylene oxide are exemplified.

[0039] Examples of the conductive additive include conductive carbon black, acetylene black, graphite, vapor-grown carbon fiber, carbon nanotube, and the like.

[0040] In the positive electrode material of the present invention, the content ratio of the electrolyte particles is preferably, for example, 1 to 50% by mass, more preferably 5 to 40% by mass, still more preferably 10 to 30% by mass, and particularly preferably 15 to 25% by mass with respect to the total mass of the electrolyte particles, the positive electrode active material, the binder, and the conductive additive.

[0041] In the positive electrode material of the present invention, the content ratio of the positive electrode active material is preferably, for example, 30 to 80% by mass, more preferably 40 to 70% by mass, and still more preferably 45 to 60% by mass with respect to the total mass of the electrolyte particles, the positive electrode active material, the binder, and the conductive additive.

[0042] In the positive electrode material of the present invention, the content ratio of the conductive additive is preferably, for example, 1 to 30% by mass, more preferably 3 to 20% by mass, and still more preferably 5 to 15% by mass with respect to the total mass of the electrolyte particles, the positive electrode active material, the binder, and the conductive additive.

[0043] Since the positive electrode material of the present invention contains electrolyte particles, a three-dimensional electron conduction network in the positive electrode material is constructed, resulting in excellent electron conduction of lithium ions. As a result, excellent battery capacity and cycle stability can be imparted to the all-solid-state lithium ion battery. In particular, as shown in FIG. 4 described later, the positive electrode material of the present invention is particularly advantageous for electron conduction of lithium ions because the positive electrode active material and the electrolyte particles are in close contact with each other.

[0044] 2. Cathode for all-solid-state lithium-ion battery The positive electrode for all-solid-state lithium-ion batteries of the present invention (hereinafter, may be abbreviated as "positive electrode") includes the positive electrode material of the present invention described above. The positive electrode of the present invention can impart excellent battery capacity and cycle stability to all-solid-state lithium-ion batteries. Therefore, the positive electrode material of the present invention can be suitably used as an electrode incorporated in all-solid-state lithium-ion batteries.

[0045] The positive electrode of the present invention is formed, for example, by forming a positive electrode material on a current collector. The type of the current collector is not particularly limited, and for example, current collectors used in known positive electrodes can be widely adopted. Examples of the current collector include metal foils such as aluminum, titanium, platinum, molybdenum, stainless steel, and copper. The shape of the metal foil is, for example, a porous body, a foil, a plate, a mesh made of fibers, etc.

[0046] The positive electrode of the present invention is manufactured, for example, by a manufacturing method including the following steps 1 and 2. Step 1: A step of applying a slurry containing the electrolyte particles and a solvent onto a current collector to form a coating film. Step 2: A step of obtaining the positive electrode material by thermally pressing the coating film.

[0047] The slurry used in Step 1 contains, in addition to the electrolyte particles and the solvent, components necessary for forming the positive electrode material. Therefore, the slurry can further contain the positive electrode active material, the binder, and the conductive assistant described above in addition to the electrolyte particles. Solvents contained in the slurry include chlorinated hydrocarbons such as chloroform and 1,2-dichloroethane; ether compounds such as diethyl ether and tetrahydrofuran; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; ketone compounds such as acetone and methyl ethyl ketone; ester compounds such as vinyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol, and t-butanol; formamides such as N,N-dimethylformamide and N,N-dimethylacetamide; pyrrolidones such as 2-pyrrolidone and N-methylpyrrolidone; dimethyl sulfoxide, etc.

[0048] Among these, the solvent preferably does not dissolve electrolyte particles, and from this perspective, pyrrolidone-based solvents such as 2-pyrrolidone and N-methylpyrrolidone are preferred.

[0049] In the above slurry, the content ratio of the electrolyte particles is preferably, for example, 1 to 50% by mass, more preferably 5 to 40% by mass, still more preferably 10 to 30% by mass, and particularly preferably 15 to 25% by mass with respect to the total mass of the electrolyte particles, the positive electrode active material, the binder, and the conductive assistant.

[0050] In the above slurry, the content ratio of the positive electrode active material is preferably, for example, 30 to 80% by mass, more preferably 40 to 70% by mass, and still more preferably 45 to 60% by mass with respect to the total mass of the electrolyte particles, the positive electrode active material, the binder, and the conductive assistant.

[0051] In the above slurry, the content ratio of the conductive assistant is preferably, for example, 1 to 30% by mass, more preferably 3 to 20% by mass, and still more preferably 5 to 15% by mass with respect to the total mass of the electrolyte particles, the positive electrode active material, the binder, and the conductive assistant.

[0052] The method for preparing the above slurry is not particularly limited. For example, a slurry can be obtained by mixing a predetermined material containing electrolyte particles with a solvent.

[0053] In the above step 1, the above slurry is applied onto the current collector to form a coating film. The application method is not particularly limited. For example, known coating means can be widely used. When forming a coating film on the current collector, after applying the slurry onto the current collector, it can be heated under appropriate conditions. When the solvent dries, a coating film is formed on the current collector. The heating method and heating conditions are not particularly limited. For example, it is 60 to 150°C, preferably 70 to 100°C.

[0054] In Step 2, the coating film is hot-pressed. Thereby, a target positive electrode material is formed on the current collector, and a positive electrode is obtained.

[0055] The method of hot pressing is not particularly limited. For example, hot pressing can be performed using a known hot press machine. The temperature of hot pressing is, for example, 50 to 200°C, preferably 70 to 180°C, more preferably 80 to 150°C. Also, the pressure during hot pressing is, for example, 0.1 to 5 MPa, preferably 0.5 to 4 MPa, more preferably 1 to 3 MPa.

[0056] By such hot pressing, the positive electrode active material and the electrolyte particles in the positive electrode material are in close contact, a highly three-dimensional electron conduction network is constructed, resulting in excellent electron conduction of lithium ions. As a result, excellent battery capacity and cycle stability can be imparted to the all-solid-state lithium-ion battery.

[0057] 3. All-solid-state lithium-ion battery The all-solid-state lithium-ion battery of the present invention includes the positive electrode, a negative electrode, and a solid electrolyte.

[0058] The negative electrode can broadly include, for example, the negative electrodes provided in conventional all-solid-state lithium-ion batteries. For example, the negative electrode can have a structure in which an active material is supported on a metal foil. Examples of the metal foil include aluminum, titanium, platinum, molybdenum, stainless steel, copper, etc. The shape of the metal foil includes, for example, a porous body, a foil, a plate, a mesh made of fibers, etc. Examples of the active material of the negative electrode include metals such as Li, Na, K, Mg, Al, Zn; graphite and other carbon materials; Si(C)-based, Si(O)-based or Sn-based alloys or metal oxides; Li4Ti5O 12 ; and the like.

[0059] In the all-solid-state lithium-ion battery of the present invention, as the solid electrolyte, for example, a sheet formed by hot pressing the aforementioned electrolyte particles can be used. The conditions for hot pressing in this case can be the same as those described above, and hot pressing can be performed using a known hot press machine. The temperature of hot pressing is, for example, 50 to 200 °C, preferably 70 to 180 °C, and more preferably 80 to 150 °C. Also, the pressure during hot pressing is, for example, 0.1 to 5 MPa, preferably 0.5 to 4 MPa, and more preferably 1 to 3 MPa.

[0060] In addition to the above, the solid electrolytes conventionally provided in all-solid-state lithium-ion batteries can also be widely used. For example, the solid electrolyte can be configured to include a base material and an electrolyte.

[0061] Examples of the base material include Li 10 GeP2S 12 , xLi2S-(1-x)P2S5 (0.6 ≦ x ≦ 0.85) and Na 11 Sn2PS 12 and other sulfide-based electrolytes; Na3PSe4; Li 3x La 2 / 3-x TiO3 (0 ≦ x ≦ 0.16) and other oxide-based electrolytes;, Li 1+x Al x Ti 2-x (PO4)3 (0 ≦ x ≦ 0.5) (LATP); Li x La3M2O 12 (3 ≦ x ≦ 7.5, M = Ta, Nb, Zr); Na3Zr2Si2PO 12 ; polymer-based electrolytes; and the like. Examples of the polymer-based electrolyte include polyethylene oxide (PEO) or PVDF (polyvinylidene fluoride).

[0062] The type of electrolyte contained in the solid electrolyte is not particularly limited, and for example, known electrolytes applicable to solid electrolytes for all-solid-state lithium-ion batteries can be mentioned. Examples of the electrolyte include LiPF6, LiClO4, LiTFSI, NaClO4, NaBF4, and the like.

[0063] In addition, examples of the solid electrolyte include hybrid electrolytes formed by mixing known inorganic electrolytes. The solid electrolyte may further contain, in addition to the electrolyte additive, the base material, and other electrolytes, various additives applied to solid electrolytes for all-solid-state lithium-ion batteries, for example. The thickness of the solid electrolyte is not particularly limited and can be, for example, 30 to 150 μm.

[0064] As the separator, known separators applied to all-solid-state lithium-ion batteries can be used. For example, polyolefin resins such as polyethylene and polypropylene; polyimide; polyvinyl alcohol; fluororesins such as end-aminoated polyethylene oxide polytetrafluoroethylene; acrylic resins; nylon; aromatic aramid; inorganic glass; ceramics, etc. Materials in the form of porous membranes, non-woven fabrics, woven fabrics, etc. can be used.

[0065] The size and shape of the battery can be appropriately determined according to the use of the battery. The all-solid-state lithium-ion battery is, for example, a secondary battery. There is also no particular limitation on the method of assembling the all-solid-state lithium-ion battery, and an all-solid-state lithium-ion battery can be obtained by the same method as known assembling methods.

[0066] In identifying the inventions included in the present disclosure, each configuration (properties, structure, function, etc.) described in each embodiment of the present disclosure may be combined in any manner. That is, the present disclosure includes all the subjects consisting of all possible combinations of each configuration described in this specification.

Examples

[0067] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the aspects of these examples.

[0068] (Production Example 1) Pellets of a polyether block amide copolymer (PEBA2533 manufactured by Arkema) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a lithium salt were mixed at a mass ratio of 75:25 (polyether block amide copolymer (1.5 g): LiTFSI (0.5 g)), and this was added to 8 g of N,N-dimethylacetamide (DMAc). Then, a gel was obtained by maintaining the temperature at 60°C. After that, it was cooled to room temperature and then the gel was pulverized. The pulverization was carried out in a mortar, and the obtained pulverized material was sieved through a micron-sized mesh. Thereby, electrolyte particles were obtained.

[0069] (Example 1) As a positive electrode active material, 60% by mass of LiFePO4, 10% by mass of PVDF as a binder, 10% by mass of SuperP as a conductive assistant, and 20% by mass of the electrolyte particles obtained in Production Example 1 were added to N-methyl-2-pyrrolidone (NMP), and stirred at room temperature (25°C) for 2 hours to prepare a slurry. This slurry was applied onto an aluminum foil (current collector) and dried at 80°C for 24 hours to form a coating film on the aluminum foil. Next, the coating film on the aluminum foil was hot-pressed to form a positive electrode material on the aluminum foil, and this was obtained as a positive electrode. The hot pressing was carried out using SINTO CYPT Digital-Press L Type, with a temperature of 100°C, a pressure of 2 MPa, and a pressing time of 0.5 hours.

[0070] (Comparative Example 1) A commercially available LiFePO4-based electrode (1.5 mAh cm -2 , manufactured by Hokuden Co., Ltd.) was prepared as the positive electrode.

[0071] (Comparative Example 2) A positive electrode was obtained in the same manner as in Example 1 except that the electrolyte particles obtained in Production Example 1 were not used.

[0072] (Fabrication of Coin Cell) Circular pellets with a diameter of 12 mm cut from the positive electrodes of the examples or comparative examples and negative electrodes made of lithium metal of the same size were prepared. The thickness of both electrodes was 0.1 mm. The solid electrolyte was obtained by hot pressing the electrolyte particles obtained in Production Example 1. The hot pressing was carried out using a SINTO CYPT Digital-Press L Type, with a temperature of 100 °C, a pressure of 2 MPa, and a pressing time of 0.5 hours. By assembling these positive electrodes, negative electrodes, and solid electrolytes, a coin cell as an all-solid-state lithium-ion battery was obtained. The assembled coin cell was measured for its electrochemical performance (battery performance) using a LAND battery test system "CT2001A" (Wuhan LAND electronics Co., Ltd., China). Here, the measurement temperature was 60 °C. The coin cell was constructed inside a glove box filled with Ar (both the H2O and O2 concentrations were 0.1 ppm or less). The measurement conditions were 60 °C, a voltage range of 2.5 to 4.0 V, and a current density of 0.2 C.

[0073] Figure 1 shows the results of SEM observation of the cross-section of the positive electrode materials formed on the positive electrodes of the examples and comparative examples. Specifically, (A) in Figure 1 is the positive electrode of Comparative Example 1, and (B) is the positive electrode of Example 1. As a result, it was found that the positive electrode material formed on the positive electrode of Example 1 was formed more densely than the positive electrode material formed on Comparative Example 1.

[0074] Figure 2 is a graph showing the capacity retention performance at 60 °C of a coin cell equipped with the positive electrode of Comparative Example 1 (in Figure 2, "CE" on the second Y-axis means Coulomb efficiency. The same applies to Figure 3(B) described later). From the results of Figure 2, the specific capacity of the cathode of Comparative Example 1 was at most 90 mAhg -1 and remained there.

[0075] Figure 3 shows the results of the full cell performance of a coin cell equipped with the positive electrode of Example 1. (A) is the voltage profile of the coin cell at various charge and discharge rates cycled at 60 °C, and (B) is the cycle performance of the coin cell at various charge and discharge rates cycled at 60 °C (current density 0.1 mAcm -2 ).

[0076] As can be seen from FIG. 3, the coin cell including the positive electrode of Example 1 maintained stability even after 12 cycles, and had a current density of 0.1 mA cm -2 and achieved a high specific capacity of 125 mAh g -1 .

[0077] FIG. 4 schematically shows the three-dimensional electron conduction network in the positive electrode material, where (A) is the positive electrode material of Comparative Example 1 and (B) is the positive electrode material of Example 1. In Comparative Example 1 (FIG. 4(A)), the contact between the positive electrode active material and the electrolyte particles was insufficient. In contrast, in Example 1 (FIG. 4(B)), since it contains electrolyte particles, these are interposed between the positive electrode active material and the contact becomes sufficient. As a result, it is considered that the ion conduction network becomes extremely good. The electrolyte particles exist without dissolving in the solvent (NMP) in the slurry used when preparing the positive electrode material. Then, when the coating film formed by the volatilization of the solvent is thermally pressed, the electrolyte particles and the positive electrode active material are connected to each other. As a result, it is presumed that this is advantageous for the conduction of Li ions. On the other hand, in the case of not containing electrolyte particles as in the conventional case, for example, an electrolyte base material such as polyethylene oxide (PEO) dissolves in the solvent and is mixed with the active material and the conductive additive, so that only a double conduction network of ions and electrons is formed, and it is presumed that the conduction effect of ions and electrons cannot be sufficiently obtained.

Claims

1. A cathode material for an all-solid-state lithium-ion battery, comprising at least electrolyte particles, wherein the electrolyte particles contain a polyether block amide copolymer and a lithium salt, and is a cathode material for an all-solid-state lithium-ion battery.

2. The cathode material according to Claim 1, wherein the polyether block amide copolymer has a polyether moiety and a polyamide moiety in the structural unit.

3. The structural unit of the polyether block amide copolymer is represented by the following general formula (1): -(CO-PA-COO-PE-O)- (1) (wherein PA represents a polyamide moiety and PE represents a polyether moiety) and is the cathode material according to Claim 2.

4. The cathode material according to Claim 1, further comprising a cathode active material, a binder, and a conductive assistant.

5. A cathode for an all-solid-state lithium-ion battery, comprising the cathode material according to any one of Claims 1 to 4.

6. An all-solid-state lithium-ion battery, comprising the cathode according to Claim 5.

7. A method for manufacturing the cathode for an all-solid-state lithium-ion battery according to Claim 5, comprising a step of applying a slurry containing the electrolyte particles and a solvent onto a current collector to form a coating film, and a step of obtaining the cathode material by thermally pressing the coating film and is a method for manufacturing a cathode for an all-solid-state lithium-ion battery.

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