Electrode Material and Battery

Abstract

An electrode material 1000 of the present disclosure includes an active material 110 and a solid electrolyte 100. The length of an interface 120 between the active material 110 and the solid electrolyte 100 per unit area of a cross-section of the electrode material 1000 is 29 μm / μm 2 or more, and the filling ratio of the electrode material 1000 is 80% or more. A battery 2000 of the present disclosure is provided with: a first electrode 201; a second electrode 203; and an electrolyte layer 202 positioned between the first electrode 201 and the second electrode 203. At least one selected from the group consisting of the first electrode 201 and the second electrode 203 includes the electrode material 1000 according to the present disclosure.

Description

Technical Field

[0001] The present disclosure relates to an electrode material and a battery.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a battery for forming a good conduction path for electrons and ions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the prior art, further improvement in the charging capacity of the battery is desired.

Means for Solving the Problems

[0005] The electrode material of the present disclosure is an active material, a solid electrolyte, and an electrode material containing the length of the interface between the active material and the solid electrolyte per unit area of the cross section of the electrode material is 0.29 μm / μm 2 or more, and the filling rate of the electrode material is 80% or more.

Effects of the Invention

[0006] According to the present disclosure, the charging capacity of the battery can be improved.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] (Knowledge on which the present disclosure is based) In an all-solid-state lithium-ion battery, a structure is required in which both electrons and lithium ions are efficiently supplied to the active material dispersed in the electrode. In general positive and negative electrodes, an electrode structure that achieves both an electron conduction path formed by contact between particles of the active material and an ion conduction path formed by contact and connection between particles of the solid electrolyte is desirable. However, in the prior art, an electrode structure that exhibits good characteristics as an all-solid-state battery has not been clarified.

[0009] (Outline of one aspect according to the present disclosure) The electrode material according to the first aspect of the present disclosure is an active material, a solid electrolyte, and an electrode material containing the length of the interface between the active material and the solid electrolyte per unit area of the cross section of the electrode material is 0.29 μm / μm 2 or more, and the filling rate of the electrode material is 80% or more.

[0010] According to the first aspect, it is possible to achieve both a lithium ion conduction path and an electron conduction path, and the charging capacity of the battery is improved.

[0011] In the second aspect of the present disclosure, for example, in the electrode material according to the first aspect, the content of the active material in the electrode material may be 40 wt% or more and 80 wt% or less. According to such a configuration, the active material and the solid electrolyte are likely to form a good dispersion state.

[0012] In a third aspect of the present disclosure, for example, in the electrode material according to the first or second aspect, the solid electrolyte may have lithium ion conductivity. According to such a configuration, a high-capacity lithium ion battery can be provided using the electrode material.

[0013] In a fourth aspect of the present disclosure, for example, in the electrode material according to any one of the first to third aspects, the length of the interface may be 0.95 μm / μm 2 or less. According to such a configuration, the internal resistance of the electrode material can be further reduced.

[0014] In a fifth aspect of the present disclosure, for example, in the electrode material according to the fourth aspect, the length of the interface may be 0.571 μm / μm 2 or less. According to such a configuration, the internal resistance of the electrode material can be further reduced.

[0015] In a sixth aspect of the present disclosure, for example, in the electrode material according to any one of the first to fifth aspects, the filling rate may be 99% or less. According to such a configuration, further high capacity of the battery becomes possible.

[0016] In a seventh aspect of the present disclosure, for example, in the electrode material according to the sixth aspect, the filling rate may be 93.1% or less. According to such a configuration, further high capacity of the battery becomes possible.

[0017] In an eighth aspect of the present disclosure, for example, in the electrode material according to any one of the first to seventh aspects, the active material may be a negative electrode active material. According to such a configuration, the charging capacity of the battery can be further improved.

[0018] In a ninth aspect of the present disclosure, for example, in the electrode material according to the ninth aspect, the negative electrode active material may contain at least one selected from the group consisting of graphite, silicon, silicon alloy, silicon oxide, tin, tin alloy, and tin oxide. According to such a configuration, a battery having a large charging capacity and excellent charge and discharge characteristics can be provided.

[0019] In a tenth aspect of the present disclosure, for example, in the electrode material according to the ninth aspect, the negative electrode active material may contain graphite. According to such a configuration, a battery having a large charge capacity and excellent charge-discharge characteristics can be provided.

[0020] In an eleventh aspect of the present disclosure, for example, in the electrode material according to any one of the first to seventh aspects, the active material may be a positive electrode active material. According to such a configuration, the charge capacity of the battery can be improved.

[0021] In a twelfth aspect of the present disclosure, for example, in the electrode material according to the eleventh aspect, the positive electrode active material may contain a metal composite oxide. According to such a configuration, the charge capacity of the battery can be improved.

[0022] In a thirteenth aspect of the present disclosure, for example, in the electrode material according to the twelfth aspect, the metal composite oxide may contain at least one selected from the group consisting of Mn, Co, Ni, and Al and Li. According to such a configuration, the charge capacity of the battery can be improved.

[0023] The battery according to a fourteenth aspect of the present disclosure a first electrode, a second electrode, an electrolyte layer positioned between the first electrode and the second electrode, and includes at least one selected from the group consisting of the first electrode and the second electrode includes an electrode material according to any one of the first to thirteenth aspects.

[0024] According to the fourteenth aspect, the charge capacity of the battery can be improved.

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0026] (Embodiment 1) FIG. 1 is a cross-sectional view showing a schematic configuration of the electrode material 1000 in Embodiment 1.

[0027] The electrode material 1000 in Embodiment 1 includes a solid electrolyte 100, an active material 110, an interface 120, and voids 130. The interface 120 is an interface formed by the contact between the solid electrolyte 100 and the active material 110.

[0028] The electrode material 1000 may be shaped. In this specification, the "cross-section of the electrode material 1000" means the cross-section of the shaped electrode material 1000, typically the cross-section of the electrode. FIG. 1 shows the cross-section of the electrode material 1000 shaped into a desired shape.

[0029] The active material 110 has a particle shape. In the electrode material 1000, particles of a plurality of active materials 110 are in contact with each other, thereby forming an electron conduction path. The solid electrolyte 100 fills the spaces between the particles of the active material 110. The solid electrolyte 100 may also have a particle shape. A large number of particles of the solid electrolyte 100 are compressed and bonded to each other, thereby forming an ion conduction path.

[0030] Here, the observation area when observing the cross-section of the electrode material 1000 is defined as A (unit: μm 2 ). The total length of the interfaces 120 confirmed within the observation area is defined as L (unit: μm). The interface perimeter Z is defined as Z = L / A. The interface perimeter Z in the electrode material 1000 is 0.29 μm / μm 2 or more.

[0031] As a method for calculating the interface perimeter Z, for example, the following method can be used.

[0032] The electrode material 1000 is processed by a cross-section polisher to form a smooth cross-section. At this time, the direction of the cross-section processing may be in any direction of the electrode material 1000. For example, when the electrode material 1000 has a plate-like shape, a cross-section parallel to the in-plane direction of the plate-like electrode material 1000 may be formed, a cross-section parallel to the thickness direction of the plate-like electrode material 1000 may be formed, or a cross-section non-parallel to both the in-plane direction and the thickness direction may be formed.

[0033] The formed cross-section is observed by a scanning electron microscope (SEM) to obtain a cross-sectional image. Since it is desirable to evaluate the average morphology of the electrode material 1000, it is desirable that a sufficiently wide area is observed by SEM with respect to the median diameter of the particle group of the active material 110 contained in the electrode material 1000. For example, when the median diameter of the particle group of the active material 110 contained in the electrode material 1000 is D (unit: μm), the observation area A satisfies A≧(20D) 2 is satisfied.

[0034] Next, from the obtained cross-sectional image, a measurement region where the observation area A satisfies A≧(20D) 2 is selected and analyzed using the image processing software Image J. By using the Analyze Particles function of Image J, in the cross-sectional image of the electrode material 1000, the active material 110 or the solid electrolyte 100 is determined as particles. The length of the interface 120 between the active material 110 and the solid electrolyte 100 is calculated. By this image analysis method, the total perimeter length of the particles is calculated.

[0035] At the interface between the solid electrolyte 100 and the active material 110, there may also be other substances such as a binder, a dispersant, and a conductive aid. However, when those substances are not clearly confirmed in the cross-sectional image, the particles of interest are targeted for the calculation of the total perimeter length.

[0036] In addition, as shown in FIG. 1, isolated particles may appear in the cross-sectional image. However, even if the particles are isolated in the cross-sectional image, there is a possibility that they are in contact with other particles at positions not appearing in the cross-section. Therefore, it is acceptable to include the isolated particles in the calculation of the total perimeter length.

[0037] Next, by dividing the total perimeter length by the observation area, the length of the interface between the active material and the solid electrolyte per unit area, that is, the interface perimeter length Z, is calculated.

[0038] In the cross-sectional image, when the particles of the active material 110 or the particles of the solid electrolyte 100 are aggregated, by determining either the aggregate of the particles of the active material 110 or the aggregate of the particles of the solid electrolyte 100 as a particle, the interface 120 between the active material 110 and the solid electrolyte 100 can be easily recognized by image recognition. For example, when the solid electrolytes 100 are connected to each other in the cross-sectional image and form a large single aggregate, the length around this large aggregate represents the length of the interface 120 between the active material 110 and the solid electrolyte 100. Also, which of the aggregate of the active material 110 and the aggregate of the solid electrolyte 100 should be determined as a particle by the image analysis software is selected according to the dispersion state of the particles in the electrode material 1000.

[0039] When it is difficult to calculate the total perimeter length by image analysis due to the influence of voids, conductive aids, etc. or the low contrast between the active material 110 and the solid electrolyte 100, the cross-sectional image may be appropriately processed by image processing software so that particle determination is easy. When it is difficult to perform image processing using the cross-sectional image, a separate image tracing the interface in the cross-sectional image may be prepared, and the interface perimeter length Z may be calculated by processing the separate image.

[0040] Also, for noise removal after image processing, relatively small particles among the particles determined as particles are not applied to the calculation of the interface perimeter length. Specifically, particles having a cross-sectional area of 1% or less with respect to the average cross-sectional area of the particles determined as particles in the cross-sectional image are not applied to the calculation of the interface perimeter length.

[0041] In the electrode material 1000, the ratio of the voids 130 occupying the space per unit volume is defined as ε, and the filling rate P (%) is defined as P = (1 - ε) × 100. The filling rate P in the electrode material 1000 is 80% or more.

[0042] The filling rate can be calculated from the volume of the electrode material 1000, the weight of the electrode material 1000, the true density of the active material 110, the true density of the solid electrolyte 100, and the mixing ratio of the materials. However, the filling rate may also be calculated by other methods such as the pycnometer method.

[0043] According to the above configuration, the charging capacity of the battery can be improved.

[0044] In this specification, "charging capacity" means the charging capacity of the battery per unit weight of the active material 110.

[0045] According to Patent Document 1, when the average particle diameter of the granulated powder formed by the active material and the solid electrolyte is 20 to 53 μm and the active materials and the solid electrolytes in the granulated powder are adjacent to each other, good charge-discharge characteristics can be obtained. However, the dispersion state of the active material and the solid electrolyte has not been clarified.

[0046] On the one hand, as a result of intensive studies by the present inventors, it has been found that the interfacial perimeter length between the active material and the solid electrolyte and the filling rate in the electrode have a great influence on the characteristics of all-solid-state lithium-ion batteries. The interfacial perimeter length is an index indicating the lithium-ion conduction path formed by the solid electrolyte in the electrode and is also an index indicating the characteristics of the interfacial formation between the active material and the solid electrolyte. During the charge and discharge of all-solid-state batteries, the larger the interfacial perimeter length, the easier it is for the lithium ions of the active material present in the electrode to be transferred. The filling rate is an index indicating the characteristics of the contact state of the active material and the solid electrolyte in the formed electrode. When the filling rate is low, the contact between solid electrolytes, the contact between the solid electrolyte and the active material, and the contact between active materials become weak, and the charge capacity decreases. In particular, when the interfacial perimeter length is long, the proportion of the solid electrolyte present between the active materials increases, and the electronic conductivity in the electrode ensured by the contact between the active materials tends to decrease. Therefore, even when the interfacial perimeter length is long, when the filling rate is low, the contact between the active materials is weak, and the electronic conductivity in the electrode decreases. As a result, the charge capacity decreases.

[0047] Therefore, in order to solve the above problems and realize a high-capacity all-solid-state lithium-ion battery, it is necessary to increase the interfacial perimeter length and the filling rate and make the lithium-ion conduction path and the electronic conduction path in the electrode compatible.

[0048] In the configuration of the present disclosure, when observing the cross section of the electrode material 1000, in other words, the cross section of the electrode, the interfacial perimeter length Z is 0.29 μm / μm 2 or more, and the filling rate P of the electrode material 1000 is 80% or more. At this time, the lithium-ion conduction path and the electronic conduction path can be made compatible, and the charge capacity of the battery is improved.

[0049] In Embodiment 1, the interfacial perimeter length Z is 0.29 μm / μm 2 or more and 0.95 μm / μm 2 or less. Even when the interfacial perimeter length Z is 0.95 μm / μm 2In the following cases, the lithium ion conduction path borne by the solid electrolyte 100 does not become too long, and an increase in the internal resistance of the electrode material 1000 can be suppressed. Therefore, the battery can operate at high power. Also, the interface perimeter length Z is 0.571 μm / μm 2 It may be as follows. Thereby, the internal resistance of the electrode material 1000 can be further reduced.

[0050] The method of controlling the interface perimeter length Z to 0.29 μm / μm 2 The method of controlling it above is not particularly limited. For example, the interface perimeter length Z can be controlled by a kneading process of the active material 110 and the solid electrolyte 100. In the manufacturing process of the electrode material 1000, when mixing the powder of the active material 110 and the powder of the solid electrolyte 100, it is desirable to select a kneading method in which the particle group is likely to be subjected to a shearing force. For example, an automatic mortar, a planetary stirrer, a mixer having a stirring blade, etc. may be used. Also, inside the manufactured electrode material 1000, it is desirable that the solid electrolyte 100 and the active material 110 form a good dispersion state and are uniformly mixed. However, the processing time required for uniform mixing varies depending on the materials used for the electrode material 1000. Therefore, it is recommended to appropriately collect a part of the electrode material 1000 during the kneading process and manufacture the electrode material 1000 while measuring the interface perimeter length Z.

[0051] In the electrode material 1000 of Embodiment 1, the filling rate P may be 80% or more. When the filling rate P is 80% or more, sufficient contact between the active material 110 and the solid electrolyte 100 is ensured, and the charge capacity is improved. Also, the filling rate P may be 99% or less. When the filling rate P is 99% or less, it is possible to suppress a decrease in the charge capacity due to cracks occurring in the particles of the active material 110 due to the expansion and contraction of the active material 110 during the charge and discharge process of the battery. Therefore, the battery can be made to have a higher capacity. Also, the filling rate P may be 93.1% or less. Thereby, the battery can be made to have an even higher capacity.

[0052] The method for controlling the filling rate P of the electrode material 1000 to 80% or more is not particularly limited. For example, the filling rate is controlled by a compression process after mixing the active material 110 and the solid electrolyte 100. In the compression process, for example, a hydraulic press, a mechanical press, etc. can be used. Also, a hot press for heating the electrode material 1000 during the compression process may be used. However, depending on the material used for the electrode material 1000, the required press pressure, the required heating temperature, and the required processing time are different. For example, when the press pressure is set to 1000 MPa or more, there is a possibility that the active material 110 may crack or the electrode material 1000 may crack due to residual stress. In the compression process, suitable conditions are selected according to the material used for the electrode material 1000.

[0053] As the solid electrolyte 100, for example, a solid electrolyte having lithium ion conductivity can be used. In this case, a high-capacity lithium ion battery can be provided using the electrode material 1000.

[0054] As the solid electrolyte 100, at least one selected from inorganic solid electrolytes and organic solid electrolytes can be used. The solid electrolyte 100 may contain at least one selected from the group consisting of sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, polymer solid electrolytes, and complex hydride solid electrolytes. Specific examples of sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, polymer solid electrolytes, and complex hydride solid electrolytes are shown in Embodiment 2. At least one selected from the group consisting of all the solid electrolytes exemplified in Embodiment 2 can be used as the solid electrolyte 100.

[0055] In order to achieve a good dispersion state, it is desirable that the solid electrolyte 100 is made of a soft material. From this viewpoint, a sulfide solid electrolyte and / or a halide solid electrolyte is suitable as the solid electrolyte 100.

[0056] The shape of the solid electrolyte 100 in Embodiment 1 is not particularly limited, and may be, for example, needle-shaped, spherical, ellipsoidal, flaky, or the like. For example, the shape of the solid electrolyte 100 may be particulate.

[0057] The shape of the active material 110 in Embodiment 1 is not particularly limited, and may be, for example, needle-shaped, spherical, ellipsoidal, or the like. For example, the shape of the active material 110 may be particulate.

[0058] For example, when the shape of the solid electrolyte 100 in Embodiment 1 is particulate (e.g., spherical), the median diameter may be 0.01 μm or more and 100 μm or less. When the median diameter is 0.01 μm or more, the contact interface between the particles of the solid electrolyte 100 does not increase too much, and an increase in the ionic resistance inside the electrode material 1000 can be suppressed. Therefore, the battery can operate at high output.

[0059] When the median diameter of the solid electrolyte 100 is 100 μm or less, the active material 110 and the solid electrolyte 100 are likely to form a good dispersion state in the electrode material 1000. Therefore, it is easy to increase the capacity of the battery.

[0060] In Embodiment 1, the median diameter of the solid electrolyte 100 may be smaller than the median diameter of the active material 110. Thereby, the solid electrolyte 100 and the active material 110 can form a better dispersion state in the electrode material 1000.

[0061] The median diameter of the active material 110 in Embodiment 1 may be 0.1 μm or more and 100 μm or less.

[0062] When the median diameter of the active material 110 is 0.1 μm or more, the active material 110 and the solid electrolyte 100 are likely to form a good dispersion state in the electrode material 1000. As a result, the charging characteristics of the battery are improved.

[0063] When the median diameter of the active material 110 is 100 μm or less, the diffusion rate of lithium in the active material 110 is sufficiently ensured. Therefore, the battery can operate at high power.

[0064] The median diameter of the active material 110 may be larger than the median diameter of the solid electrolyte 100. Thereby, the active material 110 and the solid electrolyte 100 can form a good dispersion state.

[0065] The active material 110 in Embodiment 1 includes a material having the property of occluding and releasing metal ions (for example, lithium ions). The active material 110 includes, for example, a negative electrode active material. As the negative electrode active material, a metal material, a carbon material, an oxide, a nitride, a tin compound, a silicon compound, etc. can be used. The metal material may be a single metal. Or, the metal material may be an alloy. Examples of the metal material include lithium metal, lithium alloy, etc. Examples of the carbon material include natural graphite, coke, graphitizing carbon, carbon fiber, spherical carbon, artificial graphite, amorphous carbon, etc. From the viewpoint of capacity density, at least one selected from the group consisting of silicon (Si), tin (Sn), silicon compounds, and tin compounds can be preferably used.

[0066] The active material 110 may include, for example, a positive electrode active material. As the positive electrode active material, for example, a metal composite oxide, a transition metal fluoride, a polyanion material, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxysulfide, and a transition metal oxynitride can be used. In particular, when a lithium-containing transition metal oxide is used as the positive electrode active material, the manufacturing cost can be reduced and the average discharge voltage can be increased.

[0067] In Embodiment 1, the metal composite oxide selected as the active material 110 may contain Li and at least one element selected from the group consisting of Mn, Co, Ni, and Al. Examples of such materials include Li(NiCoAl)O2, Li(NiCoMn)O2, LiCoO2, etc. For example, the positive electrode active material may be Li(NiCoMn)O2.

[0068] The active material 110 may contain a single active material or may contain a plurality of active materials having different compositions from each other.

[0069] According to the above configuration, the charging capacity of the battery can be improved.

[0070] In Embodiment 1, the particles of the solid electrolyte 100 and the particles of the active material 110 may be in contact with each other as shown in FIG. 1.

[0071] The electrode material 1000 of Embodiment 1 may include a plurality of particles of the solid electrolyte 100 and a plurality of particles of the active material 110.

[0072] In Embodiment 1, the content of the solid electrolyte 100 and the content of the active material 110 may be the same as or different from each other.

[0073] When the total amount of the electrode material 1000 is 100 wt%, the content of the active material 110 can be, for example, 40 wt% or more and 80 wt% or less. By appropriately adjusting the content of the active material 110, the active material 110 and the solid electrolyte 100 are likely to form a good dispersion state.

[0074] The electrode material 1000 may contain only the active material 110 and the solid electrolyte 100. In other words, the electrode material 1000 may consist essentially of the active material 110 and the solid electrolyte 100. According to such a configuration, the energy density of the battery can be improved. "Containing only the active material 110 and the solid electrolyte 100" means that other materials are not intentionally included in the electrode material 1000 except for unavoidable impurities.

[0075] Generally, the "median diameter" means the particle diameter when the cumulative deposition in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction type measuring device.

[0076] (Embodiment 2) Next, Embodiment 2 will be described. Descriptions overlapping with those of Embodiment 1 described above will be omitted as appropriate.

[0077] FIG. 2 is a cross-sectional view showing a schematic configuration of the battery 2000 in Embodiment 2.

[0078] The battery 2000 in Embodiment 2 includes a first electrode 201, an electrolyte layer 202, and a second electrode 203.

[0079] The first electrode 201 includes an electrode material 1000.

[0080] The electrolyte layer 202 is disposed between the first electrode 201 and the second electrode 203.

[0081] According to the above configuration, the charging capacity of the battery 2000 can be improved.

[0082] Regarding the weight ratio "w:100 - w" of the active material 110 and the solid electrolyte 100 included in the first electrode 201, 40 ≤ w ≤ 80 may be satisfied. When 40 ≤ w is satisfied, the energy density of the battery 2000 is sufficiently ensured. Also, when w ≤ 80 is satisfied, the battery 2000 can operate at high power.

[0083] The thickness of the first electrode 201 may be 10 μm or more and 500 μm or less. When the thickness of the first electrode 201 is 10 μm or more, the energy density of the battery 2000 is sufficiently ensured. When the thickness of the first electrode 201 is 500 μm or less, the battery 2000 can operate at high power.

[0084] The electrolyte layer 202 is a layer containing an electrolyte. The electrolyte is, for example, a solid electrolyte. That is, the electrolyte layer 202 may be a solid electrolyte layer.

[0085] As the solid electrolyte contained in the electrolyte layer 202, for example, an inorganic solid electrolyte having lithium ion conductivity is used. As the inorganic solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or the like is used.

[0086] As the solid electrolyte contained in the electrolyte layer 202, a halide solid electrolyte may be used.

[0087] The halide solid electrolyte is represented by, for example, the following compositional formula (1). In compositional formula (1), α, β, and γ are each independently a value greater than 0. M contains at least one element selected from the group consisting of metal elements other than Li and metalloid elements. X contains at least one selected from the group consisting of F, Cl, Br, and I.

[0088] LiαMβXγ ··· Formula (1)

[0089] The metalloid elements include B, Si, Ge, As, Sb, and Te. The metal elements include all elements contained in Groups 1 to 12 of the periodic table excluding hydrogen, and all elements contained in Groups 13 to 16 of the periodic table excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se. That is, the metal elements are a group of elements that can become cations when forming a halogen compound and an inorganic compound.

[0090] As the halide solid electrolyte, Li3YX6, Li2MgX4, Li2FeX4, Li(Al,Ga,In)X4, Li3(Al,Ga,In)X6, or the like can be used.

[0091] According to the above configuration, the output density of the battery 2000 can be improved. In addition, the thermal stability of the battery 2000 can be improved, and the generation of harmful gases such as hydrogen sulfide can be suppressed.

[0092] In the present disclosure, when an element in a formula is represented as "(Al, Ga, In)", this notation indicates at least one element selected from the group of elements within the parentheses. That is, "(Al, Ga, In)" is synonymous with "at least one selected from the group consisting of Al, Ga, and In". The same applies to other elements. The halide solid electrolyte exhibits excellent ionic conductivity.

[0093] In composition formula (1), M may contain Y (=yttrium). That is, the halide solid electrolyte contained in the electrolyte layer 202 may contain Y as a metal element.

[0094] The halide solid electrolyte containing Y may be a compound represented by the following composition formula (2).

[0095] Li a M b Y c X6 ··· Formula (2)

[0096] Composition formula (2) satisfies a + mb + 3c = 6 and c > 0. In composition formula (2), M contains at least one element selected from the group consisting of metal elements and metalloid elements other than Li and Y. m is the valence of M. X contains at least one selected from the group consisting of F, Cl, Br, and I. M contains at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb. Specific examples of the halide solid electrolyte containing Y include Li3YF6, Li3YCl6, Li3YBr6, Li3YI6, Li3YBrCl5, Li3YBr3Cl3, Li3YBr5Cl, Li3YBr5I, Li3YBr3I3, Li3YBrI5, Li3YClI5, Li3YCl3I3, Li3YCl5I, Li3YBr2Cl2I2, Li3YBrCl4I, Li 2.7 Y 1.1 Cl6, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 Y 0.3 Zr0.7 Cl6 or the like can be used.

[0097] According to the above configuration, the output density of the battery 2000 can be further improved.

[0098] The solid electrolyte contained in the electrolyte layer 202 may contain a sulfide solid electrolyte.

[0099] According to the above configuration, since a sulfide solid electrolyte excellent in reduction stability is included, a low-potential negative electrode material such as graphite or metallic lithium can be used, and the energy density of the battery 2000 can be improved.

[0100] Examples of the sulfide solid electrolyte include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 and the like can be used. LiX, Li2O, MO q 、Li p MO q and the like may be added. Here, the element X in "LiX" is at least one element selected from the group consisting of F, Cl, Br, and I. The element M in "MO q " and "Li p MO q " is at least one element selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. The p and q in "MO q " and "Li p MO q " are each an independent natural number.

[0101] Examples of the sulfide solid electrolyte include lithium-containing sulfides such as Li2S-P2S5-based, Li2S-SiS2-based, Li2S-B2S3-based, Li2S-GeS2-based, Li2S-SiS2-LiI-based, Li2S-SiS2-Li3PO4-based, Li2S-Ge2S2-based, Li2S-GeS2-P2S5-based, and Li2S-GeS2-ZnS-based.

[0102] The solid electrolyte contained in the electrolyte layer 202 may contain at least one selected from the group consisting of an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte.

[0103] Examples of the oxide solid electrolyte include NASICON-type solid electrolytes typified by LiTi2(PO4)3 and its element-substituted products, perovskite-type solid electrolytes of the (LaLi)TiO3 system, Li 14 ZnGe4O 16 , LISICON-type solid electrolytes typified by Li4SiO4, LiGeO4 and their element-substituted products, garnet-type solid electrolytes typified by Li7La3Zr2O 12 and its element-substituted products, glasses or glass ceramics in which materials such as Li2SO4 and Li2CO3 are added to base materials containing Li-B-O compounds such as Li3N and its H-substituted product, Li3PO4 and its N-substituted product, LiBO2, and Li3BO3 can be used.

[0104] Examples of the oxide solid electrolyte include lithium-containing metal oxides such as Li2O-SiO2 and Li2O-SiO2-P2O5, Li x P y O 1-z N z and other lithium-containing metal nitrides, lithium-containing transition metal oxides such as lithium phosphate (Li3PO4) and lithium titanate can be used.

[0105] Examples of the oxide solid electrolyte include Li7La3Zr2O 12 (LLZ), Li 1.3 Al 0.3 Ti 1.7 (PO4)3 (LATP), (La,Li)TiO3 (LLTO), etc. are used.

[0106] As the polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. By having an ethylene oxide structure, the polymer compound can contain a large amount of the lithium salt, so that the ionic conductivity can be further increased. As the lithium salt, LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), LiC(SO2CF3)3, etc. can be used. As the lithium salt, one kind of lithium salt selected from these may be used alone, or a mixture of two or more kinds of lithium salts selected from these may be used.

[0107] As the complex hydride solid electrolyte, for example, LiBH4-LiI, LiBH4-P2S5, etc. can be used.

[0108] The electrolyte layer 202 may contain only one kind of solid electrolyte selected from the group of the above-described solid electrolytes, or may contain two or more kinds of solid electrolytes selected from the group of the above-described solid electrolytes. The plurality of solid electrolytes have different compositions from each other. For example, the electrolyte layer 202 may contain a halide solid electrolyte and a sulfide solid electrolyte.

[0109] The thickness of the electrolyte layer 202 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 202 is 1 μm or more, the first electrode 201 and the second electrode 203 are less likely to short-circuit. When the thickness of the electrolyte layer 202 is 300 μm or less, the battery 2000 can operate at high output.

[0110] The second electrode 203 contributes to the operation of the battery 2000 as the counter electrode of the first electrode 201.

[0111] The following will be described by taking the case where the first electrode 201 is a negative electrode as an example. That is, the electrode material 1000 is used for the negative electrode of the battery 2000. In this case, the active material 110 is a negative electrode active material. By using the electrode material 1000 for the negative electrode of the battery 2000, the charging capacity of the battery 2000 can be further improved.

[0112] When the active material 110 is a negative electrode active material, the negative electrode active material may include at least one selected from the group consisting of graphite, silicon, silicon alloy, silicon oxide, tin, tin alloy, and tin oxide. The negative electrode active material preferably includes graphite. By using these materials, a battery 2000 having a large charging capacity and excellent charge and discharge characteristics can be provided.

[0113] When the first electrode 201 includes a negative electrode active material, the second electrode 203 may include a material having the property of occluding and releasing metal ions (for example, lithium ions), and includes, for example, a positive electrode active material. As the positive electrode active material, for example, a metal composite oxide, a transition metal fluoride, a polyanion material, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxysulfide, and a transition metal oxynitride can be used. In particular, when a lithium-containing transition metal oxide is used as the positive electrode active material, the manufacturing cost can be reduced and the average discharge voltage can be increased.

[0114] The metal composite oxide selected as the positive electrode active material contained in the second electrode 203 may include Li and at least one element selected from the group consisting of Mn, Co, Ni, and Al. Examples of such materials include Li(NiCoAl)O2, Li(NiCoMn)O2, LiCoO2, etc. For example, the positive electrode active material may be Li(NiCoMn)O2.

[0115] Even when the first electrode 201 is a positive electrode, the electron conduction path and the lithium ion conduction path in the first electrode 201 are ensured, and the charging capacity is improved. The configuration in which the first electrode 201 is a positive electrode can be implemented in the same manner as the configuration in which the first electrode 201 is a negative electrode.

[0116] When the first electrode 201 contains a positive electrode active material, the second electrode 203 includes, for example, a negative electrode active material. As the negative electrode active material, a metal material, a carbon material, an oxide, a nitride, a tin compound, a silicon compound, etc. can be used. The metal material may be a single metal. Or, the metal material may be an alloy. Examples of the metal material include lithium metal, lithium alloy, etc. Examples of the carbon material include natural graphite, coke, carbon in the process of graphitization, carbon fiber, spherical carbon, artificial graphite, amorphous carbon, etc. From the viewpoint of capacity density, silicon (Si), tin (Sn), silicon compounds, and tin compounds can be preferably used.

[0117] The second electrode 203 may contain a solid electrolyte. According to the above configuration, the lithium ion conductivity inside the second electrode 203 is increased, and the battery 2000 can operate at high output. As the solid electrolyte in the second electrode 203, the materials exemplified as the solid electrolyte contained in the electrolyte layer 202 may be used.

[0118] The median diameter of the particles of the active material contained in the second electrode 203 may be 0.1 μm or more and 100 μm or less. When the median diameter of the particles of the active material is 0.1 μm or more, the active material particles and the solid electrolyte can form a good dispersion state. Thereby, the charging capacity of the battery 2000 is improved. When the median diameter of the particles of the active material is 100 μm or less, the diffusion rate of lithium in the particles of the active material is sufficiently ensured. Therefore, the battery 2000 can operate at high output.

[0119] The median diameter of the particles of the active material may be larger than the median diameter of the particles of the solid electrolyte. Thereby, a good dispersion state between the active material and the solid electrolyte can be formed.

[0120] Regarding the volume ratio "v:100 - v" of the active material and the solid electrolyte contained in the second electrode 203, 30 ≤ v ≤ 95 may be satisfied. When 30 ≤ v is satisfied, the energy density of the battery 2000 is sufficiently ensured. Also, when v ≤ 95 is satisfied, the battery 2000 can operate at high output.

[0121] The thickness of the second electrode 203 may be 10 μm or more and 500 μm or less. When the thickness of the second electrode 203 is 10 μm or more, the energy density of the battery 2000 is sufficiently ensured. When the thickness of the second electrode 203 is 500 μm or less, the battery 2000 can operate at high power.

[0122] The second electrode 203 may contain the electrode material 1000. In this case, any of the configurations shown in the example of the first electrode 201 may be used.

[0123] According to the above configuration, the lithium ion conductivity and electron conductivity inside the second electrode 203 are enhanced, and the charging capacity is improved.

[0124] The first electrode 201 and the second electrode 203 may contain one or more solid electrolytes for the purpose of enhancing the ion conductivity. As the solid electrolyte, the materials exemplified as the solid electrolyte contained in the electrolyte layer 202 may be used.

[0125] At least one of the first electrode 201, the electrolyte layer 202, and the second electrode 203 may contain a binder for the purpose of improving the adhesion between particles. The binder is used to improve the binding property of the material constituting the electrode. Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, methyl polyacrylate ester, ethyl polyacrylate ester, hexyl polyacrylate ester, polymethacrylic acid, methyl polymethacrylate ester, ethyl polymethacrylate ester, hexyl polymethacrylate ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, carboxymethyl cellulose, and the like. Further, as the binder, a copolymer of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene may be used. Also, two or more selected from these may be mixed and used as the binder.

[0126] At least one of the first electrode 201 and the second electrode 203 may contain a conductive aid for the purpose of enhancing electron conductivity. Examples of the conductive aid include graphites such as natural graphite or artificial graphite, carbon blacks such as acetylene black and ketjen black, conductive fibers such as carbon fibers or metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide or potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene. When a carbon conductive aid is used, cost reduction can be achieved.

[0127] When a conductive additive and a binder that do not contribute to charge and discharge are clearly included in the electrode material 1000, the conductive additive and the binder are excluded from the calculation of the total perimeter length. For example, the conductive additive and the binder can be distinguished from the solid electrolyte 100 and the active material 110 by elemental mapping of the cross-section or the like. By excluding the conductive additive and the binder, the total length of the interface 120 between the solid electrolyte 100 and the active material 110 can be calculated.

[0128] The battery 2000 in Embodiment 2 can be configured as a battery having various shapes such as a coin type, a cylindrical type, a rectangular type, a sheet type, a button type, a flat type, and a laminated type.

Example

[0129] Hereinafter, the details of the present disclosure will be described using examples and comparative examples.

[0130] <<Example 1>> [Production of Sulfide Solid Electrolyte A] In an argon glove box with an Ar atmosphere having a dew point of -60°C or lower, Li2S and P2S5 were weighed so that the molar ratio was Li2S:P2S5 = 75:25. These were pulverized and mixed in a mortar to obtain a mixture. Then, using a planetary ball mill (manufactured by Fritsch, P-7 type), the mixture was milled at 510 rpm for 10 hours to obtain a glassy solid electrolyte. The glassy solid electrolyte was heat-treated in an inert atmosphere at 270°C for 2 hours. As a result, Li2S-P2S5, which is a glass-ceramic solid electrolyte, was obtained as the sulfide solid electrolyte A.

[0131] [Production of Electrode Material] In an argon glove box, spherical graphite having a median diameter of 8 μm and the sulfide solid electrolyte A were weighed at a weight ratio of 40:60. By mixing these in an agate mortar, the electrode material of Example 1 was produced.

[0132] The electrode material of Example 1 is a negative electrode material.

[0133] <<Example 2>> [Preparation of Sulfide Solid Electrolyte B] In an argon glove box with an Ar atmosphere having a dew point of -60°C or lower, Li2S and P2S5 were weighed so that the molar ratio was Li2S:P2S5 = 75:25. A mixture of Li2S, P2S5, and ethyl propionate was put into a resin container of a test tube type together with a zirconia ball with a diameter of 4 mm and sealed.

[0134] Thereafter, the resin container was set in a shaker (manufactured by ASONE, CUTE MIXER-CM1000) and shaken at a speed of about 1500 times / min for 6 hours to obtain a suspension. The zirconia ball was removed from the suspension, and the obtained suspension was centrifuged with a centrifuge (manufactured by Hitachi Koki Co., Ltd., GR22GIII). A paste-like sample was recovered by removing the supernatant solvent.

[0135] Next, the paste-like sample was vacuum-dried at room temperature for 30 minutes to obtain a white powder. Finally, the powdered sample was subjected to vacuum heat treatment at 170°C for 2 hours to obtain sulfide solid electrolyte B.

[0136] [Preparation of Electrode Material] In an argon glove box, spherical graphite with a median diameter of 8 μm and sulfide solid electrolyte B were weighed at a weight ratio of 60:40. By mixing these in an agate mortar, the electrode material of Example 2 was prepared.

[0137] The electrode material of Example 2 is a negative electrode material.

[0138] <<Example 3>> [Preparation of Electrode Material] The electrode material of Example 3 was obtained by the same method as in Example 2, except that the weight ratio of spherical graphite and sulfide solid electrolyte B was changed to 80:20.

[0139] The electrode material of Example 3 is a negative electrode material.

[0140] <<Example 4>> [Preparation of Sulfide Solid Electrolyte C] Sulfide solid electrolyte A was prepared in the same manner as in Example 1, and in a dry atmosphere with a dew point of -40°C or lower, the sulfide solid electrolyte A was pulverized and atomized by a jet mill device (manufactured by Aisin Nanotechnology Co., Ltd., NJ-50). Thereafter, in an inert atmosphere, the atomized sulfide solid electrolyte was heat-treated under the conditions of 270 degrees for 2 hours to obtain sulfide solid electrolyte C.

[0141] [Fabrication of Electrode Material] In an argon glove box, spherical graphite with a median diameter of 8 μm and sulfide solid electrolyte C were weighed at a weight ratio of 40:60. By mixing these in an agate mortar, the electrode material of Example 4 was fabricated.

[0142] The electrode material of Example 4 is a negative electrode material.

[0143] [[Example 5]] [Fabrication of Electrode Material] The electrode material of Example 5 was obtained by the same method as in Example 4, except that the weight ratio of spherical graphite to sulfide solid electrolyte C was changed to 60:40.

[0144] The electrode material of Example 5 is a negative electrode material.

[0145] [[Example 6]] [Fabrication of Electrode Material] The electrode material of Example 6 was obtained by the same method as in Example 4, except that the weight ratio of spherical graphite to sulfide solid electrolyte C was changed to 80:20.

[0146] The electrode material of Example 6 is a negative electrode material.

[0147] [[Example 7]] [Fabrication of Electrode Material] In an argon glove box, spherical graphite with a median diameter of 8 μm and a silicon compound with a median diameter of 8 μm were weighed at a weight ratio of 90:10. These were mixed in an agate mortar to obtain a mixed negative electrode active material. The mixed negative electrode active material and solid electrolyte C were weighed at a weight ratio of 70:30. A negative electrode slurry was obtained by mixing the mixed negative electrode active material, solid electrolyte C, a solvent, a dispersant, and a thickener. This negative electrode slurry was applied onto a copper foil, and the coating film was dried. Thereby, the electrode material of Example 7 was fabricated on the copper foil.

[0148] The electrode material of Example 7 is a negative electrode material.

[0149] <<Comparative Example 1>> The electrode material of Comparative Example 1 was obtained by the same method as in Example 1, except that the weight ratio of spherical graphite and sulfide solid electrolyte B was changed to 40:60.

[0150] The electrode material of Comparative Example 1 is a negative electrode material.

[0151] <<Comparative Example 2>> The electrode material of Comparative Example 2 was obtained by the same method as in Example 1, except that the weight ratio of spherical graphite and sulfide solid electrolyte A was changed to 80:20.

[0152] The electrode material of Comparative Example 2 is a negative electrode material.

[0153] <<Comparative Example 3>> [Preparation of Sulfide Solid Electrolyte D] Sulfide solid electrolyte A was prepared in the same manner as in Example 1. In an argon glove box, sulfide solid electrolyte A was classified using a precision sieve with a mesh size of 10 μm, and the powder that passed through the sieve was collected to obtain sulfide solid electrolyte D.

[0154] [Preparation of Electrode Material] In an argon glove box, spherical graphite with a median diameter of 8 μm and sulfide solid electrolyte D were weighed at a weight ratio of 80:20. By mixing these in an agate mortar, the electrode material of Comparative Example 3 was fabricated.

[0155] The electrode material of Comparative Example 3 is a negative electrode material.

[0156] [Measurement 1 of filling rate] Using the electrode materials of Examples 1 to 3, Comparative Example 1, and Comparative Example 2, the following steps were carried out.

[0157] First, 80 mg of the electrode material was put into a metal outer cylinder and pressure-molded at a pressure of 360 MPa to obtain pellets of the electrode material. Next, the film thickness and weight of the pellets were measured. Finally, using the inner diameter of the outer cylinder, the true density of the active material, and the true density of the solid electrolyte, the filling rates of the electrode materials of Examples 1 to 3, Comparative Example 1, and Comparative Example 2 were calculated.

[0158] [Measurement 2 of filling rate] Using the electrode materials of Examples 4 to 6 and Comparative Example 3, the following steps were carried out.

[0159] First, 80 mg of the electrode material was put into a metal outer cylinder and pressure-molded at a pressure of 720 MPa to obtain pellets of the electrode material. Next, the film thickness and weight of the pellets were measured. Finally, using the inner diameter of the outer cylinder, the true density of the active material, and the true density of the solid electrolyte, the filling rates of the electrode materials of Examples 4 to 6 and Comparative Example 3 were calculated.

[0160] [Measurement 3 of filling rate] Using the electrode material of Example 7, the following steps were carried out.

[0161] The electrode material of Example 7 was pressure-molded at a pressure of 600 MPa. Thereafter, the weight and film thickness of the pressure-molded electrode material were measured. Using the true densities of each material of the active material, the solid electrolyte, the dispersant, and the thickener, the filling rate of the electrode material of Example 7 was calculated.

[0162] [Measurement 1 of interfacial perimeter length] Using the electrode materials of Example 1, Example 2, and Comparative Example 1, the following steps were carried out.

[0163] First, 80 mg of the electrode material was put into a metal outer cylinder and pressure-molded at a pressure of 360 MPa to obtain pellets of the electrode material.

[0164] Next, the pellets were processed by a cross-section polisher (SM-09010, manufactured by JEOL Ltd.) to form a smooth cross-section. At this time, cross-section processing was performed in the thickness direction of the pellets.

[0165] The cross-section of the pellet was observed by SEM (SU-70, manufactured by Hitachi High-Technologies Corporation), and a cross-sectional image (magnification: 500 times) was obtained. The SEM observation area at this time was 4.5×10 4 μm 2 Since the median diameter D of the spherical graphite, which is the active material, was 8 μm, the observation area A satisfied A≧(20D) 2 .

[0166] Next, the cross-sectional image was analyzed using image processing software Image J. First, for the SEM observation area, white was specified as the background to obtain a binary image. Next, particle determination of the active material was performed from the binary image using the Analyze Particles function. For noise removal after image processing, particles having a cross-sectional area of 1% or less with respect to the average cross-sectional area of the particles determined as particles in the cross-sectional image were excluded, and the total perimeter length of the active material determined as particles was calculated. Finally, the total perimeter length calculated from the cross-sectional image was divided by the image analysis area to calculate the interface length per unit area between the active material and the solid electrolyte, that is, the interface perimeter length.

[0167] In this specification, "particle determination" means determining whether particles exist.

[0168] [Measurement of Interface Perimeter Length 2] The interface perimeter lengths in the electrode materials of Example 3 and Comparative Example 2 were measured by the same method as in Measurement 1, except that the background was specified as black.

[0169] [Measurement of Interface Perimeter Length 3] The interfacial perimeter lengths of the electrode materials of Examples 4 and 5 were measured by the same method as in Measurement 1, except that the pressure during pressure forming was set to 720 MPa.

[0170] [Measurement 4 of interfacial perimeter length] The interfacial perimeter lengths of the electrode materials of Examples 6 and Comparative Example 3 were measured by the same method as in Measurement 1, except that the pressure during pressure forming was set to 720 MPa and the background was specified as black.

[0171] [Measurement 5 of interfacial perimeter length] Using the electrode material of Example 7, the following steps were carried out.

[0172] First, 80 mg of sulfide solid electrolyte A and the electrode material formed on the copper foil of Example 7 were laminated in this order inside a metal outer cylinder. By pressure forming the laminate of copper foil / electrode material / sulfide solid electrolyte A at a pressure of 600 MPa, a pellet was obtained. The sulfide solid electrolyte A in the pellet is a supporting layer for the electrode material. By integrally forming with the electrode material, the handling of the electrode material after pressure forming becomes easy.

[0173] Thereafter, the interfacial perimeter length of the electrode material of Example 7 was measured by the same method as in Measurement 1, except that the background was specified as black and the acquisition magnification of the cross-sectional image was 800 times.

[0174] The electrode material of Example 7 contains a binder, a dispersant, and a thickener. However, the total ratio of the binder, dispersant, and thickener in the entire electrode material was less than 0.1 wt%, which was very low. Therefore, the operation of excluding the thickener was not performed in the measurement of the interfacial perimeter length.

[0175] [Fabrication of secondary battery 1] Using the electrode materials of Example 1 and Comparative Example 1 and sulfide solid electrolyte A, the following steps were carried out.

[0176] First, 80 mg of sulfide solid electrolyte A and 12 mg of electrode material were laminated in this order inside the insulating outer cylinder. By pressing and molding these at a pressure of 360 MPa, a first electrode and an electrolyte layer were obtained.

[0177] Next, as the second electrode, metal In (thickness 200 μm), metal Li (thickness 300 μm), and metal In (thickness 200 μm) were laminated on the electrolyte layer in this order. By pressing and molding the obtained laminate at a pressure of 80 MPa, a laminate composed of a first electrode, an electrolyte layer, and a second electrode was produced.

[0178] Next, stainless steel current collectors were arranged above and below the laminate, and current collection leads were attached to the current collectors.

[0179] Finally, the insulating outer cylinder was sealed using an insulating ferrule, and the inside of the insulating outer cylinder was blocked from the outside air atmosphere to fabricate a battery.

[0180] As described above, the batteries of Example 1 and Comparative Example 1 were fabricated respectively.

[0181] [Fabrication of Secondary Battery 2] A battery of Example 2 was fabricated in the same manner as Example 1, except that 8 mg of the electrode material of Example 2 was used instead of the electrode material of Example 1.

[0182] [Fabrication of Secondary Battery 3] Batteries of Example 3 and Comparative Example 2 were fabricated in the same manner as Example 1, except that 6 mg of the electrode material of Example 3 or Comparative Example 2 was used instead of the electrode material of Example 1.

[0183] [Fabrication of Secondary Battery 4] A battery of Example 4 was fabricated in the same manner as Example 1, except that 12 mg of the electrode material of Example 4 was used instead of the electrode material of Example 1, and the pressure during pressing and molding of the electrode material was changed to 720 MPa.

[0184] [Fabrication of Secondary Battery 5] A battery of Example 5 was fabricated in the same manner as in Example 1, except that 8 mg of the electrode material of Example 5 was used instead of the electrode material of Example 1, and the pressure during the pressure molding of the electrode material was changed to 720 MPa.

[0185] [Fabrication of Secondary Battery 6] A battery of Example 6 and a battery of Comparative Example 3 were fabricated in the same manner as in Example 1, except that 6 mg of the electrode material of Example 6 or Comparative Example 3 was used instead of the electrode material of Example 1, and the pressure during the pressure molding of the electrode material was changed to 720 MPa.

[0186] [Fabrication of Secondary Battery 7] A battery of Example 7 was fabricated in the same manner as in Example 1, except that the electrode material formed on the copper foil of Example 7 (coating weight 16 mg) was used instead of the electrode material of Example 1, sulfide solid electrolyte C was used instead of sulfide solid electrolyte A, and the pressure during the pressure molding of the electrode material was changed to 600 MPa.

[0187] [Charge and Discharge Test 1] Using the batteries of Examples 1 to 6 and Comparative Examples 1 to 3, a charge and discharge test was carried out under the following conditions.

[0188] The battery was placed in a thermostat at 25°C.

[0189] While pressurizing the battery to 150 MPa with a pressure jig, constant current charging was performed at a current value of 70 μA, which is 0.04 C rate (25-hour rate) with respect to the theoretical capacity of the battery, and the charging was terminated at a voltage of -0.62 V.

[0190] Here, the charging means the direction in which the Li insertion reaction into the spherical graphite, which is the negative electrode active material in the first electrode, proceeds.

[0191] In addition, the alloy InLi used for the second electrode of the batteries of Examples 1 to 6, Comparative Example 1 and Comparative Example 2 shows a potential of 0.62 V (vs. Li).

[0192] That is, the charge cut-off voltage of -0.62 V for the batteries of Examples 1 to 6, Comparative Example 1, and Comparative Example 2 corresponds to 0 V (vs. Li) when converted to the potential based on Li.

[0193] As described above, the charge capacities of the batteries of Examples 1 to 6 and Comparative Examples 1 to 3 were measured. The results are shown in Table 1 below. The charge capacity is the charge capacity per unit weight of the active material.

[0194] [Charge and Discharge Test 2] Using the battery of Example 7, a charge and discharge test was conducted under the following conditions.

[0195] The battery was placed in a constant temperature bath at 25°C.

[0196] While pressurizing the battery to 150 MPa with a pressure jig, constant current charging was performed at a current value of 140 μA, which is 0.04 C rate (25-hour rate) with respect to the theoretical capacity of the battery, and the charging was terminated at a voltage of -0.62 V.

[0197] Here, the charging means the direction in which the Li insertion reaction into the spherical graphite, which is the negative electrode active material in the first electrode, proceeds.

[0198] In addition, the alloy InLi used for the second electrode of the battery of Example 7 exhibits a potential of 0.62 V (vs. Li).

[0199] That is, the charge cut-off voltage of -0.62 V for the battery of Example 7 corresponds to 0 V (vs. Li) when converted to the potential based on Li.

[0200] As described above, the charge capacity of the battery of Example 7 was measured. The results are shown in Table 1 below.

[0201]

Table 1

[0202] <<Discussion>> As shown in Table 1, the perimeter length of the interface between the active material and the solid electrolyte is 0.29 μm / μm2 It has been confirmed that by using an electrode material that satisfies the above conditions and has a filling ratio of 80% or more, the charge capacity per unit weight of the active material of the battery is improved.

[0203] The result of Example 7 shows that even when a silicon compound is included in the electrode material as the active material, the interfacial perimeter length between the active material and the solid electrolyte is 0.29 μm / μm 2 is above the above, and as long as the filling ratio is 80% or more, it shows that the charge capacity is improved. That is, the active material in the electrode material of the present disclosure is not limited to a carbon material such as graphite. It has been confirmed by examples that it is also effective when other active materials are used.

[0204] The difference between the electrode material used in the battery of Example 1 and the electrode material used in the battery of Comparative Example 1 lies only in the method of producing the sulfide solid electrolyte. This indicates that it is difficult to form a good dispersion state between the active material and the solid electrolyte only by adjusting the content ratio of the active material in the electrode material.

Industrial Applicability

[0205] The battery of the present disclosure can be used, for example, as an all-solid-state battery.

Claims

1. An electrode material comprising: an active material; and a solid electrolyte, The length of the interface between the active material and the solid electrolyte per unit area of the cross-section of the electrode material is 0.29 μm / μm 2 or more, and wherein a filling rate of the electrode material is 80% or more, when a median diameter of the active material is D, a length of the interface is calculated by observing a region having an area of (20D) 2 or more, the electrode material.

2. In the electrode material, a content of the active material is 40 wt% or more and 80 wt% or less, The electrode material according to Claim 1.

3. The solid electrolyte has lithium ion conductivity, The electrode material according to Claim 1 or 2.

4. The length of the interface is 0.95 μm / μm 2 is as follows The electrode material according to any one of Claims 1 to 3.

5. The length of the interface is 0.571 μm / μm 2 is as follows The electrode material according to Claim 4.

6. The filling rate is 99% or less, The electrode material according to any one of Claims 1 to 5.

7. The filling rate is 93.1% or less, The electrode material according to Claim 6.

8. The active material is a negative electrode active material, The electrode material according to any one of Claims 1 to 7.

9. The negative electrode active material includes at least one selected from the group consisting of graphite, silicon, silicon alloy, silicon oxide, tin, tin alloy, and tin oxide, The electrode material according to Claim 8.

10. The negative electrode active material includes graphite, The electrode material according to Claim 9.

11. The active material is a positive electrode active material, The electrode material according to any one of Claims 1 to 7.

12. The positive electrode active material includes a metal composite oxide, The electrode material according to Claim 11.

13. The metal composite oxide includes at least one selected from the group consisting of Mn, Co, Ni, and Al, and Li, The electrode material according to Claim 12.

14. The length of the interface is calculated by obtaining an average cross-sectional area of particles determined as particles among the active material or the solid electrolyte in a cross-sectional image for calculating the length of the interface, and excluding particles having a cross-sectional area of 1% or less with respect to the average cross-sectional area, The electrode material according to any one of Claims 1 to 13.

15. A median diameter of the solid electrolyte is smaller than a median diameter of the active material, The electrode material according to any one of Claims 1 to 14.

16. A first electrode; A second electrode; An electrolyte layer positioned between the first electrode and the second electrode; Comprising At least one selected from the group consisting of the first electrode and the second electrode contains the electrode material according to any one of claims 1 to 15, Battery.

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