Electrode mixture, and electrode and battery having same

Abstract

An electrode mixture which contains an active material and a solid electrolyte and in which at least two peaks are observed in a volume particle size distribution as determined by a laser diffraction scattering particle size distribution measurement method. It is preferable that at least two peaks having peak tops are observed in the range of 0.2 [mu] m to 20 [mu] m (inclusive) of the particle size distribution, the peak top of the frequency peak having the smallest particle size among the peaks is observed in the range of 0.2 [mu] m to 5.0 [mu] m (inclusive), and the peak top of the frequency peak having the largest particle size among the peaks is observed in the range of 2.0 [mu] m to 20 [mu] m (inclusive).

Description

Technical Field

[0001] The present invention relates to an electrode mixture, an electrode having the same, and a battery. Background Art

[0002] Since a solid battery does not use a flammable organic solvent, it can not only simplify a safety device, but also has excellent manufacturing cost and productivity, and also has a feature of achieving high voltage by laminating in series in the battery.

[0003] For example, Patent Document 1 describes a solid battery including a positive electrode mixture layer containing a positive electrode active material, a negative electrode mixture layer containing a negative electrode active material, and a solid electrolyte layer disposed between the positive electrode mixture layer and the negative electrode mixture layer in a stacking direction. The solid electrolyte material in this solid battery has a bimodal particle size distribution.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-212431 Summary of the Invention

[0007] Existing solid batteries have the above advantages, but on the other hand, there are the following problems: Since an active material and a solid electrolyte need to be present in each electrode, the density in each electrode (hereinafter, also referred to as "electrode density") is reduced. When the electrode density is reduced, the energy density of the solid battery is also reduced. Therefore, in order to develop a solid battery with a higher energy density, it is necessary to increase the electrode density of each electrode.

[0008] Therefore, an object of the present invention is to provide an electrode mixture having a higher electrode density.

[0009] The present invention provides an electrode mixture containing an active material and a solid electrolyte,

[0010] and at least two peaks are observed in a volume particle size distribution based on a laser diffraction scattering type particle size distribution measurement method. Brief Description of the Drawings

[0011] Figure 1 is a volume particle size distribution of the electrode mixture of Example 1 based on a laser diffraction scattering type particle size distribution measurement method. Detailed Description of the Invention

[0012] Hereinafter, the present invention will be described based on preferred embodiments. The present invention relates to an electrode mixture containing an active material and a solid electrolyte.

[0013] The electrode mixture of the present invention preferably has at least two peaks observed in the volume particle size distribution based on the laser diffraction scattering method of particle size distribution measurement. Among them, it is preferred to observe two peaks in the volume particle size distribution. The volume particle size distribution mentioned here refers to the volume particle size distribution of the entire electrode mixture powder including the active material, the solid electrolyte, and other solid materials as required.

[0014] Observing at least two peaks in the volume particle size distribution of the electrode mixture has the following effects: Particles with relatively small particle sizes enter the gaps between particles with relatively large particle sizes to fill the gaps, thereby increasing the electrode density of the electrode mixture.

[0015] In the electrode mixture of the present invention, it is preferred to observe at least two peaks with peak tops in the range of 0.2 μm or more and 20 μm or less in the particle size distribution. Additionally, it is more preferred that the peak top of the frequency peak with the smallest particle size among the peaks is observed in the range I of 0.2 μm or more and 5.0 μm or less, and the peak top of the frequency peak with the largest particle size among the peaks is observed in the range II of 2.0 μm or more and 20 μm or less. Observing the peak top within the range II has the advantages of a higher particle density and a higher electrode density. On this basis, by observing the peak top within the range I, the particles in the range I are easily blocked between the particles in the range II, so the electrode density becomes even higher.

[0016] It should be noted that in the case where three or more peaks are observed in the volume particle size distribution, the range II can also be the value second only to the range I, or one or more peaks can be observed between the range I and the range II.

[0017] In addition, in order to further improve the above effects, it is preferred to set the content ratio of particles with relatively large particle sizes to particles with relatively small particle sizes within a certain range. Specifically, in the volume particle size distribution of the electrode mixture, when the peak with the largest particle size is set as peak A and the peak with the second largest particle size after peak A is set as peak B, the ratio of the height of peak A to the height of peak B is preferably 1.0 or more, more preferably 1.2 or more, even more preferably 1.4 or more, and preferably 10 or less, more preferably 8 or less, and further preferably 7 or less.

[0018] If the ratio of the height of peak A to the height of peak B is 10 or less, the particles with relatively small particle sizes can sufficiently fill the gaps between the particles with relatively large particle sizes. Additionally, if the ratio of the height of peak A to the height of peak B is 1.0 or more, the amount of particles among the particles with relatively small particle sizes that do not completely enter the gaps between the particles with relatively large particle sizes is suppressed, so the electrode density of the electrode mixture can be increased.

[0019] From the viewpoint of increasing the electrode density by effectively filling the gaps between particles with relatively large particle sizes with particles with relatively small particle sizes, the particle size D at the top of peak B is B The particle size D of the peak A A Ratio D B / D A It is preferably 0.05 or more and 0.5 or less, more preferably 0.07 or more and 0.4 or less, and further preferably 0.1 or more and 0.3 or less.

[0020] From the same point of view, A With D B Ratio D B / D A Under the above conditions, D B It is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 0.8 μm or more. It is preferably 5.0 μm or less, more preferably 4.0 μm or less, and even more preferably 3.0 μm or less.

[0021] From the viewpoint of reducing the intergranular gaps constituting the electrode mixture as much as possible and improving the electrode density, when the active material and the solid electrolyte contained therein are respectively subjected to laser diffraction scattering particle size distribution measurement in the electrode mixture of the present invention, at least one peak is preferably observed in the volume particle size distribution of at least one. For example, 1 peak can be observed, or 2 peaks can be observed.

[0022] The electrode mixture of the present invention has a cumulative volume 50% volume cumulative particle size D based on the laser diffraction scattering particle size distribution measurement method. EM50 It is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more, and is preferably 20 μm or less, more preferably 17 μm or less, and even more preferably 15 μm or less. EM50 When the particle size is within the above range, the particle size becomes sufficiently small relative to the electrode thickness, so that the electrode density is improved, and the uniformity and smoothness of the electrode are improved.

[0023] The BET specific surface area of ​​the electrode mixture of the present invention is preferably 0.5 m 2 / g or more, more preferably 0.7m 2 / g or more, more preferably 1.0 m 2 / g or more, preferably 5.0m 2 / g or less, more preferably 3.0m 2 / g or less, more preferably 2.5m 2 / g or less.

[0024] By setting the BET specific surface area of the electrode mixture within the above range, particles with a relatively small particle size can sufficiently contact the gaps between particles with a relatively large particle size. In addition, excessive contact between the two particles is suppressed, so that the electrode density of the electrode mixture can be increased.

[0025] The BET specific surface area is measured by the BET single-point method.

[0026] In order to set the BET specific surface area of the electrode mixture within the above range, for example, the BET specific surface areas of the active material and the solid electrolyte can be adjusted.

[0027] The electrode mixture of the present invention can be used to fabricate an electrode (positive electrode or negative electrode) by applying it to a current collector, for example. Specifically, a coating composition prepared by mixing the electrode mixture and a solvent is coated on the surface of a current collector such as an aluminum foil, dried, and then roll-pressed, whereby an electrode can be formed on the surface of the current collector. As the solvent contained in the coating composition, substances conventionally used in this technical field can be used without particular limitation.

[0028] When the electrode mixture is pressed, the particles of the solid electrolyte are crushed to fill the gaps between the particles constituting the electrode mixture. On the other hand, for the particles of the active material, rather than being crushed by pressing, a positional shift occurs. As a result, the gaps between the particles in the electrode mixture are reduced. Thereby, the electrode density and the contact area between the active material and the solid electrolyte can be increased. It should be noted that, unless otherwise specified, the "electrode mixture" in this specification includes both the electrode mixture before pressing and the electrode mixture after pressing.

[0029] Regarding the reduction of the gaps between particles caused by pressing, it becomes more effective when the gaps between the particles constituting the electrode mixture before pressing are small. Since the particles with a relatively small particle size enter the gaps between the particles with a relatively large particle size and fill the gaps in the electrode mixture of the present invention, the gaps between the particles constituting the electrode mixture before pressing are small. Therefore, by pressing, the gaps between the particles constituting the electrode mixture are further reduced, and thus an electrode mixture with a high electrode density and a large contact area between the active material and the solid electrolyte can be obtained.

[0030] Since the electrode fabricated using the electrode mixture of the present invention has a high electrode density, the energy density of a battery equipped with this electrode can be increased.

[0031] Next, the active material and the solid electrolyte contained in the electrode mixture of the present invention will be described separately.

[0032] The active material is the part that mainly contributes to the electrode reaction in the electrode mixture of the present invention. In the present invention, the active material is preferably used as a positive electrode active material.

[0033] As the active material, the following composite oxides are preferably used. The composite oxides contain: lithium (Li) element; oxygen (O) element; and one or more selected from manganese (Mn) element, nickel (Ni) element, cobalt (Co) element, iron (Fe) element, sodium (Na) element, magnesium (Mg) element, aluminum (Al) element, phosphorus (P) element, potassium (K) element, calcium (Ca) element, titanium (Ti) element, vanadium (V) element, chromium (Cr) element, copper (Cu) element, gallium (Ga) element, yttrium (Y) element, zirconium (Zr) element, niobium (Nb) element, molybdenum (Mo) element, indium (In) element, tantalum (Ta) element, tungsten (W) element, rhenium (Re) element and cerium (Ce) element. It is preferable from the viewpoint of further improving the performance of the battery containing the electrode mixture of the present invention that the composite oxide is particles formed of a spinel-type composite oxide or a lithium metal composite oxide having a layered rock salt-type crystal structure.

[0034] When the active material contains a spinel-type composite oxide, the active material preferably contains Li element, Mn element, and O element, and may further contain other elements. As the other elements, for example, an element M1 formed by a combination of one or more of Ni element, Co element, and Fe element can be cited.

[0035] Alternatively, as the other elements, for example, an element M2 formed by a combination of one or more of Na element, Mg element, Al element, P element, K element, Ca element, Ti element, V element, Cr element, Cu element, Ga element, Y element, Zr element, Nb element, Mo element, In element, Ta element, W element, Re element, and Ce element can be cited.

[0036] In the present invention, either one of element M1 and element M2 can be used, or both element M1 and element M2 can be used.

[0037] As the spinel-type composite oxide contained in the active material, for example, a spinel-type lithium-containing manganese composite oxide having a crystal structure in which a part of the Mn sites in LiMn2O 4－δ is replaced by Li element, element M1, and element M2 can be cited.

[0038] Element M1 is preferably a substitution element that is mainly helpful for exhibiting a working potential of 4.5 V or more at the metal Li reference potential. As element M1, for example, as described above, it preferably contains at least one of Ni element, Co element, and Fe element, and among them, it is particularly preferably to contain at least one of Ni element and Co element.

[0039] Element M2 is preferably a substitution element that is mainly helpful for stabilizing the crystal structure and thus improving the battery characteristics. Element M2 is a different element type from element M1.

[0040] Regarding whether the composite oxide has a spinel-type crystal structure, for example, if it fits the crystal structure model of a cubic crystal of space group Fd-3m (OriginChoice2), and the ranges of Rwp and S representing the degree of agreement between the observed intensity and the calculated intensity are Rwp < 10 or S < 2.5, it can be determined that it has a spinel-type crystal structure.

[0041] In addition, as the lithium metal composite oxide having a layered rock salt-type crystal structure contained in the active material, for example, the general formula (1): Li 1+x M 1－x O2 represents a lithium metal composite oxide having a layered rock salt-type crystal structure. By being the lithium metal composite oxide represented by the general formula (1), the performance of the battery containing the electrode binder of the present invention is further improved.

[0042] In the general formula (1), M is

[0043] (i) at least one of Ni element, Co element, Mn element, and Al element, or

[0044] (ii) a combination of at least one element among Ni element, Co element, Mn element, and Al element and at least one element among the following elements: transition metal elements existing between Group 3 and Group 11 elements of the periodic table, and typical metal elements of the second to fourth periods of the periodic table.

[0045] In addition, in the general formula (1), x is preferably, for example, -0.05 or more, more preferably -0.03 or more, and most preferably 0 or more. On the other hand, x is preferably, for example, 0.09 or less, preferably 0.07 or less, and most preferably 0.05 or less.

[0046] General formula (1): Li 1+x M 1－x In O2, "1 + x" is preferably, for example, 0.95 or more, preferably 0.97 or more, and most preferably 0.98 or more. On the other hand, "1 + x" is preferably, for example, 1.09 or less, preferably 1.07 or less, and more preferably 1.05 or less.

[0047] Examples of the transition metal elements existing between Group 3 and Group 11 elements of the periodic table and the typical metal elements up to the fourth period of the periodic table include Al, P, V, Fe, Ti, Mg, Cr, Ga, Cu, Zn, Nb, Zr, Mo, W, Ta, Re, etc.

[0048] Therefore, as the constituent element M, for example, at least one of Ni, Co, Mn, and Al is preferably used, or a combination of at least one of Ni, Co, Mn, and Al and at least one of P, V, Fe, Ti, Mg, Cr, Ga, Cu, Zn, Nb, Zr, Mo, W, Ta, and Re is used.

[0049] "M" in the general formula (1) preferably contains, for example, three elements of Mn, Co, and Ni. For example, M can be the three elements of Mn, Co, and Ni, or a combination of these three elements and at least one or more elements among other elements.

[0050] When "M" in the formula (1) contains the three elements of Mn, Co, and Ni, the molar ratios of Mn, Co, and Ni are preferably, for example, Mn:Co:Ni = 0.01 to 0.45:0.01 to 0.40:0.30 to 0.95, among which Mn:Co:Ni = 0.05 to 0.40:0.03 to 0.40:0.30 to 0.85 is preferred, and among which Mn:Co:Ni = 0.05 to 0.40:0.03 to 0.40:0.30 to 0.80 is more preferred.

[0051] In the general formula (1), for the atomic ratio of the oxygen amount, it is recorded as "2" for convenience, but it may have some deviation from the stoichiometric ratio. That is, the atomic ratio of the oxygen amount can be "2 - δ". "-δ" represents oxygen deficiency, and δ is preferably 0 or more and 0.2 or less, among which, more preferably 0.1 or less, and further preferably 0.05 or less.

[0052] Whether the lithium metal composite oxide has a layered rock salt-type crystal structure can be judged as follows. For example, if it fits with the crystal structure model of the hexagonal crystal of the space group R-3m, and the ranges of Rwp and S representing the degree of agreement between the observed intensity and the calculated intensity are Rwp < 10 or S < 2.5, it can be judged that it has a layered rock salt-type crystal structure.

[0053] The cumulative volume 50% volume particle size D of the active material based on the laser diffraction scattering particle size distribution measurement method AM50 is preferably 1 μm or more, more preferably 2 μm or more, further preferably 3 μm or more, and preferably 20 μm or less, more preferably 17 μm or less, further preferably 15 μm or less.

[0054] By making D AM50 be 20 μm or less, good contact with the solid electrolyte in the electrode mixture can be ensured, and uniform formation of the electrode layer can be achieved. In addition, by making D AM50is 1 μm or more, which can ensure good contact with the solid electrolyte in the electrode mixture and can increase the electrode density.

[0055] The BET specific surface area of the active material is preferably 0.1 m 2 / g or more, more preferably 0.15 m 2 / g or more, and further preferably 0.2 m 2 / g or more. In addition, it is preferably 1.5 m 2 / g or less, more preferably 1.3 m 2 / g or less, and further preferably 1.0 m 2 / g or less.

[0056] By setting the BET specific surface area of the active material within the above range, the active material and the solid electrolyte have a sufficient contact area. In addition, excessive contact between the active material and the solid electrolyte is suppressed, thereby enabling the electrode density of the electrode mixture to be increased.

[0057] The method for measuring the BET specific surface area is as described above.

[0058] The tapped density of the active material is preferably 1.0 g / cm 3 or more, more preferably 1.3 g / cm 3 or more, and further preferably 1.5 g / cm 3 or more. In addition, it is preferably 3.0 g / cm 3 or less, more preferably 2.9 g / cm 3 or less, and further preferably 2.8 g / cm 3 or less.

[0059] By setting the tapped density of the active material within the above range, even if the electrode mixture contains a solid electrolyte, the minimum electrode density of the battery can be ensured.

[0060] The tapped density can be measured in accordance with JIS Z 2512 using JV2000 manufactured by Copley Scientific. Specifically, 10 g of the active material is put into a graduated cylinder with a capacity of 25 cm 3 , the tap stroke is set to 3 mm, and the number of taps is set to 2500 times (250 times / minute) for measurement.

[0061] From the viewpoint of sufficiently increasing the electrode density, the content of the active material in the electrode mixture of the present invention is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 85% by mass or more. In addition, the content of the active material in the electrode mixture of the present invention can be, for example, 99% by mass or less, 98% by mass or less, or 95% by mass or less.

[0062] Next, the solid electrolyte used in the present invention will be described.

[0063] The solid electrolyte used in the present invention can be the same as the solid electrolyte used in a normal solid battery. Examples include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, halide solid electrolytes, etc. Among them, a sulfide solid electrolyte containing a sulfur (S) element is preferred from the viewpoint of having high ionic conductivity. In addition, compared with other solid electrolytes having lithium ion conductivity, the sulfide solid electrolyte is easily crushed by pressing, so it also has the advantage of easily increasing the electrode density of the electrode mixture.

[0064] The sulfide solid electrolyte in the present invention can be, for example, a substance containing a lithium (Li) element and a sulfur (S) element and having lithium ion conductivity, or a substance containing a lithium (Li) element, a phosphorus (P) element, and a sulfur (S) element and having lithium ion conductivity.

[0065] The sulfide solid electrolyte may also have a crystal phase of a thiogermanate structure.

[0066] Examples of the sulfide solid electrolyte include Li2S−P2S5, Li2S−P2S5−LiX (“X” represents one or more halogen elements), Li2S−P2S5−P2O5, Li2S−Li3PO4−P2S5, Li3PS4, Li4P2S6, Li 10 GeP2S 12 、Li 3.25 Ge 0.25 P 0.75 S4, Li7P3S 11 、Li 3.25 P 0.95 S4, Li 7－x PS 6－x X x (A solid electrolyte having a crystal phase of a thiogermanate structure, “X” represents one or more halogen elements, 0.2 < x < 2.0 or 0.2 < x < 1.8.) etc.

[0067] In order to increase the electrode density of the electrode mixture, it is preferable to greatly reduce the gaps between the particles constituting the electrode mixture. From this viewpoint, the volume median diameter D of the cumulative volume 50% by capacity of the solid electrolyte based on the laser diffraction scattering particle size distribution measurement method SE50 is preferably 0.1 μm or more, more preferably 0.3 μm or more, still more preferably 0.5 μm or more, and preferably 15 μm or less, more preferably 10 μm or less, still more preferably 5 μm or less.

[0068] By making D of the solid electrolyte SE50 have the above upper limit value, the solid electrolyte becomes likely to sufficiently enter the gaps between the active materials, and the gaps between the active materials are effectively reduced. Further, by making D of the solid electrolyte SE50 have the above lower limit value, the solid electrolyte more effectively reduces the gaps between the active materials.

[0069] From the same viewpoint, the ratio of D SE50 to D AM50 , D SE50 / D AM50 is preferably 0.05 or more, more preferably 0.07 or more, and still more preferably 0.1 or more. Further, D SE50 / D AM50 is preferably 0.5 or less, more preferably 0.4 or less, and still more preferably 0.3 or less.

[0070] From the viewpoint of extremely reducing the gaps between the particles constituting the electrode mixture, it is preferable to observe at least two peaks in the volume particle size distribution obtained by laser diffraction scattering type particle size distribution measurement of the solid electrolyte.

[0071] Further, the peak top of one of these peaks is preferably observed in the range of 0.2 μm or more and 2.0 μm or less. Further, the peak top of the other peak is preferably observed in the range of 2.0 μm or more and 5.0 μm or less.

[0072] It should be noted that when only one peak is observed in the volume particle size distribution, from the viewpoint of extremely reducing the gaps between the particles constituting the electrode mixture, it is preferable that the particle diameter of the peak top is observed in the range of 0.2 μm or more and 5.0 μm or less.

[0073] The Young's modulus of the solid electrolyte used in the present invention is, for example, preferably 30 GPa or less, more preferably 28 GPa or less, and still more preferably 25 GPa or less. On the other hand, the above Young's modulus is preferably, for example, 5 GPa or more, more preferably 10 or more, and still more preferably 13 GPa or more. By making the Young's modulus within the above range, when the electrode mixture containing the active material and the solid electrolyte is subjected to a pressing treatment, the solid electrolyte can more effectively fill the gaps between the crushed materials at the interface with the active material, and further, the contact area between the solid electrolyte and the active material can be increased.

[0074] Regarding the Young's modulus of the solid electrolyte, the force curve measurement of the solid electrolyte can be performed using an atomic force microscope (AFM), and it can be calculated from the obtained force curve.

[0075] The BET specific surface area of the solid electrolyte is preferably 2 m 2 / g or more, more preferably 3 m 2 / g or more, further preferably 4.0 m 2 / g or more, and preferably 15 m 2 / g or less, more preferably 14.5 m 2 / g or less, further preferably 14 m 2 / g or less.

[0076] The solid electrolyte having a BET specific surface area within the above range has a sufficient contact area with the active material, and in addition, excessive contact with the active material is suppressed, thereby enabling the electrode density of the electrode mixture to be increased.

[0077] From the viewpoint that the proportion of the solid electrolyte entering the gaps between the active materials increases when the BET specific surface area of the solid electrolyte is larger than that of the active material and the electrode density can be increased, it is preferable. From this viewpoint, when the BET specific surface area of the solid electrolyte is Ss (m 2 / g) and the BET specific surface area of the active material is Sa (m 2 / g), the value of Ss relative to Sa (Ss / Sa) is preferably, for example, 1 or more, more preferably 2 or more, and further preferably 4 or more. On the other hand, the above Ss / Sa is preferably, for example, 150 or less, more preferably 100 or less, and further preferably 70 or less.

[0078] The measurement method of the BET specific surface area is as described above.

[0079] The tapped density of the solid electrolyte is preferably 0.1 g / cm 3 or more, more preferably 0.2 g / cm 3 or more, further preferably 0.3 g / cm 3 or more, and preferably 1.0 g / cm 3 or less, more preferably 0.9 g / cm 3 or less, further preferably 0.8 g / cm 3 or less.

[0080] By setting the tapped density of the solid electrolyte within the above range, even if the electrode mixture contains the solid electrolyte, a sufficient electrode density of the battery can be ensured.

[0081] The measurement method of the tapped density is as described above.

[0082] In the electrode mixture of the present invention, the content of the solid electrolyte is preferably 5% by mass or more, more preferably 7% by mass or more, further preferably 10% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, and further preferably 30% by mass or less.

[0083] By setting the content of the solid electrolyte to 5% by mass or more, sufficient ionic conductivity can be obtained. In addition, by setting the content of the solid electrolyte to 40% by mass or less, the proportion of the solid electrolyte entering the gaps between the active materials increases, and the electrode density can be improved.

[0084] The electrode mixture of the present invention may also contain other materials in addition to the active material and the solid electrolyte as needed. Examples of such materials include conductive aids and binders. As the conductive aid, there is no particular limitation as long as it is a material that can be used in the electrode mixture. Examples of the conductive aid include conductive substances formed of carbon materials.

[0085] The other materials can be used alone or in combination of multiple kinds. As long as the total content of the other materials in the electrode mixture is within a range that does not impair the performance of the solid battery, there is no particular limitation, and it can be set to, for example, 0.1% by mass or more and 10% by mass or less.

[0086] By using the electrode mixture of the present invention as the positive electrode mixture and applying it to the current collector, a positive electrode layer can be formed, for example. Then, a battery can be fabricated from the positive electrode layer, the electrolyte, and the negative electrode layer. When the electrolyte is a solid electrolyte, a solid battery can be fabricated from the positive electrode layer, the solid electrolyte layer having the solid electrolyte, and the negative electrode layer.

[0087] As the negative electrode active material constituting the negative electrode layer, for example, carbon, silicon, lithium, etc. can be used.

[0088] A solid battery can be fabricated, for example, by laminating and pressure-forming the positive electrode layer, the solid electrolyte layer, and the negative electrode layer. The "solid battery" includes, in addition to a solid battery that does not contain any liquid or gel-like substance as the electrolyte, a mode that contains, for example, 50% by mass or less, 30% by mass or less, 10% by mass or less of a liquid or gel-like substance as the electrolyte.

[0089] The battery having the electrode mixture of the present invention is preferably a lithium ion battery. In addition, the battery having the electrode mixture of the present invention can be a primary battery or a secondary battery, and among them, it is preferably used in a secondary battery, and particularly preferably used in a lithium secondary battery. The "lithium secondary battery" widely includes the meaning of a secondary battery that is charged and discharged by the movement of lithium ions between the positive electrode and the negative electrode.

[0090] The present invention has been described based on its preferred embodiments, but the present invention is not limited to the above embodiments. For example, in the above embodiments, an electrode mixture mainly suitable for a solid battery having lithium ion conductivity has been described, but the target battery of the present invention is not limited to a solid battery having lithium ion conductivity.

[0091] The above embodiments of the present invention include the following technical ideas.

[0092] [1] An electrode mixture, which contains an active material and a solid electrolyte, and at least two peaks are observed in the volume particle size distribution based on the laser diffraction scattering type particle size distribution measurement method.

[0093] [2] The electrode mixture according to [1], wherein at least two peaks with peaks are observed in the range of 0.2 μm or more and 20 μm or less in the particle size distribution.

[0094] The peak top of the frequency peak with the smallest particle size among the peaks is observed in the range of 0.2 μm or more and 5.0 μm or less.

[0095] The peak top of the frequency peak with the largest particle size among the peaks is observed in the range of 2.0 μm or more and 20 μm or less.

[0096] [3] The electrode mixture according to [1] or [2], wherein in the particle size distribution,

[0097] When the frequency peak with the largest particle size is set as peak A,

[0098] and the frequency peak with the particle size second only to peak A is set as peak B,

[0099] the ratio value of the height of peak A to the height of peak B is 1.0 or more and 10.0 or less.

[0100] [4] The electrode mixture according to any one of [1] to [3], wherein when performing laser diffraction scattering type particle size distribution measurement on the solid electrolyte and the active material respectively, at least two peaks are observed in the volume particle size distribution of at least one of them.

[0101] [5] The electrode mixture according to [4], wherein at least two peaks are observed in the particle size distribution of the solid electrolyte, and the peak top of one of these peaks is observed in the range of 0.1 μm or more and 5.0 μm or less.

[0102] [6] The electrode mixture according to any one of [1] to [5], wherein the active material contains:

[0103] Lithium (Li) element;

[0104] Oxygen (O) element; and

[0105] One or more selected from the group consisting of manganese (Mn), nickel (Ni), cobalt (Co), iron (Fe), sodium (Na), magnesium (Mg), aluminum (Al), phosphorus (P), potassium (K), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), copper (Cu), gallium (Ga), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), indium (In), tantalum (Ta), tungsten (W), rhenium (Re), and cerium (Ce).

[0106] [7] The electrode mixture according to any one of [1] to [6], wherein the solid electrolyte is a sulfide solid electrolyte.

[0107] [8] The electrode mixture according to any one of [1] to [7], wherein the Young's modulus of the solid electrolyte is 30 GPa or less.

[0108] [9] The electrode mixture according to any one of [1] to [8], wherein the volume-based cumulative particle size D of the active material at 50% by volume based on the laser diffraction scattering particle size distribution measurement method AM50 is 1.0 μm or more and 15 μm or less.

[0109]

[10] The electrode mixture according to any one of [1] to [9], wherein the volume-based cumulative particle size D of the solid electrolyte at 50% by volume based on the laser diffraction scattering particle size distribution measurement method SE50 is 0.1 μm or more and 15 μm or less.

[0110]

[11] The electrode mixture according to any one of [1] to

[10] , wherein the BET specific surface area of the active material is 0.1 m 2 / g or more and 1.5 m 2 / g or less.

[0111]

[12] The electrode mixture according to any one of [1] to

[11] , wherein the BET specific surface area of the solid electrolyte is 2.0 m 2 / g or more and 15.0 m 2 / g or less.

[0112]

[13] The electrode mixture according to any one of [1] to

[12] , wherein the BET specific surface area is 0.5 m 2 / g or more and 5.0 m 2 / g or less.

[0113]

[14] The electrode mixture according to any one of [1] to

[13] , wherein the tapped density of the active material is 1.0 g / cm3 3.0 g / cm³ or more 3 and below.

[0114]

[15] The electrode mixture according to any one of [1] to

[14] , wherein the tapped density of the solid electrolyte is 0.1 g / cm³ 3 or more and 1.0 g / cm³ 3 or less.

[0115]

[16] The electrode mixture according to any one of [1] to

[15] , further comprising a conductive additive.

[0116]

[17] An electrode formed by applying the electrode mixture according to any one of [1] to

[16] on a current collector.

[0117]

[18] A battery comprising the electrode according to

[17] .

[0118] Examples

[0119] Hereinafter, the present invention will be further specifically described by way of examples. However, the scope of the present invention is not limited to the examples.

[0120] [Examples 1 to 4, Comparative Example 1]

[0121] In this example and the comparative example, as the active material, X-1 to X-3, which are layered rock salt type composite oxides, were used, and as the solid electrolyte, Y-1 and Y-2, which are sulfide solid electrolytes, were used. The active materials X-1 to X-3 are lithium oxides containing lithium element, oxygen element, nickel element, manganese element, and cobalt element. In addition, the solid electrolytes Y-1 and Y-2 have a crystalline phase with a thiogermanate structure.

[0122] For the active materials X-1 to X-3 and the solid electrolytes Y-1 and Y-2, the particle diameters at the peaks, D AM50 and D SE50 were calculated from the volume particle size distribution obtained by the laser diffraction scattering type particle size distribution measurement method. In addition, similarly, the following were also calculated: the volume particle size D AM10 of the active material at 10% by volume of the cumulative volume based on the laser diffraction scattering type particle size distribution measurement method, the volume particle size D AM90 of the active material at 90% by volume of the cumulative volume, the volume particle size D SE10 of the solid electrolyte at 10% by volume of the cumulative volume, and the volume particle size D SE90 of the solid electrolyte at 90% by volume of the cumulative volume. Further, the BET specific surface area, tapped density, and Young's modulus were measured by the above method. These results are shown in Table 1.

[0123] It should be noted that in the volume particle size distribution of any one of the active substances X-1 and X-2 and the solid electrolytes Y-1 and Y-2, only 1 peak top was observed. On the other hand, 2 peak tops were observed in the volume particle size distribution of the active substance X-3.

[0124] [Table 1]

[0125]

[0126] Next, the active substance powder, the solid electrolyte powder, the conductive assistant (VGCF (registered trademark)) powder, and the binder were weighed in a mass ratio of 85:10:2:3 and mixed with a mortar to prepare an electrode mixture. As the active substance and the solid electrolyte, the substances described in Table 2 were used. For the obtained electrode mixture, D was calculated from the volume particle size distribution obtained by the laser diffraction scattering type particle size distribution measurement method. EM50 . Similarly, the volume cumulative particle size D of the electrode mixture at a cumulative volume of 10% by volume based on the laser diffraction scattering type particle size distribution measurement method was also calculated. EM10 and the volume cumulative particle size D of the electrode mixture at a cumulative volume of 90% by volume. EM90 . In addition, the particle size D of the peak top of the peak A, which is the peak with the largest particle size, was calculated. A and the particle size D of the peak top of the peak B, which is the peak with the second largest particle size after the peak A. B . Further, the ratio of the height of the peak A to the height of the peak B was calculated. These results are shown in Table 2. In addition, the volume particle size distribution of the electrode mixture of Example 1 based on the laser diffraction scattering type particle size distribution measurement method is shown in Figure 1 .

[0127] It should be noted that 2 peaks (peak A and B) were observed in the volume particle size distribution of all the examples. On the other hand, only 1 peak was observed in the volume particle size distribution of Comparative Example 1.

[0128] In addition, according to the above method, the BET specific surface area of the electrode mixtures of the examples and the comparative examples was measured. The results are shown in Table 2.

[0129] Next, the electrode density of the electrode mixture of the examples and comparative examples was measured. First, the active material powder, solid electrolyte powder, powder of conductive assistant (VGCF (registered trademark)), and binder were weighed at a mass ratio of 85:10:2:3, and a mixed solvent of tetralin - anisole was added in an appropriate amount, and a rotation - revolution type mixer (THINKY MIXER (registered trademark)) was used for mixing to prepare the electrode mixture. As the active material and solid electrolyte, the substances described in Table 2 were used. Next, the electrode mixture was coated on a stainless - steel current collector foil by a doctor - blade method and vacuum - dried at 120 °C for 6 hours. The electrode thus obtained was cut into 106 mm × 61 mm using a Thomson knife without pressing. The thickness of the electrode was measured using a micrometer, and the thickness of the current collector foil was subtracted from this value to calculate the thickness T (cm) of the electrode mixture. In addition, the mass of the electrode was measured, and the mass of the current collector foil was subtracted from this value to calculate the mass M (g) of the electrode mixture. Using these measured values, the electrode density d (g / cm 3 ) of the electrode mixture was calculated based on the following formula.

[0130] d = M / (10.6×6.1×T)

[0131] The results are shown in Table 2.

[0132] [Table 2]

[0133]

[0134] As shown in Table 2, it can be seen that compared with the electrode mixtures of the comparative examples in which only one peak was observed in the volume particle size distribution based on the laser diffraction scattering type particle size distribution measurement method, the electrode mixtures of the examples in which two peaks were observed in the volume particle size distribution have a higher electrode density and fewer gaps between the particles constituting the electrode mixture.

[0135] Industrial Applicability

[0136] By the present invention, an electrode mixture with a high electrode density is provided.

Claims

1. An electrode mixture, which comprises an active material and a solid electrolyte, At least two peaks are observed in the volume particle size distribution of the electrode mixture by laser diffraction scattering particle size distribution measurement method.

2. The electrode mixture according to claim 1, wherein At least two peaks with peaks are observed in the range of 0.2 μm or more and 20 μm or less in the particle size distribution, The peak top of the frequency peak with the smallest particle size among the peaks is observed in the range of 0.2 μm or more and 5.0 μm or less, The peak top of the frequency peak with the largest particle size among the peaks is observed in the range of 2.0 μm or more and 20 μm or less.

3. The electrode mixture according to claim 1, wherein, In the particle size distribution, When the frequency peak with the largest particle size is set as peak A, When the frequency peak with the particle size second only to peak A is set as peak B, The ratio of the height of peak A to the height of peak B is 1.0 or more and 10.0 or less.

4. The electrode mixture according to claim 1, wherein, When laser diffraction scattering particle size distribution measurement is performed on the solid electrolyte and the active material respectively, at least two peaks are observed in the volume particle size distribution of at least one of them.

5. The electrode mixture according to claim 4, wherein, At least two peaks are observed in the particle size distribution of the solid electrolyte, and the peak top of one of the peaks is observed in the range of 0.1 μm or more and 5.0 μm or less.

6. The electrode mixture according to claim 1, wherein, The active material contains: Lithium (Li) element; Oxygen (O) element; and One or more selected from manganese (Mn) element, nickel (Ni) element, cobalt (Co) element, iron (Fe) element, sodium (Na) element, magnesium (Mg) element, aluminum (Al) element, phosphorus (P) element, potassium (K) element, calcium (Ca) element, titanium (Ti) element, vanadium (V) element, chromium (Cr) element, copper (Cu) element, gallium (Ga) element, yttrium (Y) element, zirconium (Zr) element, niobium (Nb) element, molybdenum (Mo) element, indium (In) element, tantalum (Ta) element, tungsten (W) element, rhenium (Re) element and cerium (Ce).

7. The electrode mixture according to claim 1, wherein, The solid electrolyte is a sulfide solid electrolyte.

8. The electrode mixture according to claim 1, wherein, The Young's modulus of the solid electrolyte is 30 GPa or less.

9. The electrode mixture according to claim 1, wherein, The volume median diameter D of the active substance at a cumulative volume of 50% based on the laser diffraction scattering particle size distribution measurement method AM50 is 1.0 μm or more and 15 μm or less.

10. The electrode mixture according to claim 1, wherein, The volume median diameter D of the solid electrolyte at a cumulative volume of 50% based on the laser diffraction scattering particle size distribution measurement method SE50 is 0.1 μm or more and 15 μm or less.

11. The electrode mixture according to claim 1, wherein, The BET specific surface area of the active substance is 0.1 m 2 / g or more and 1.5 m 2 / g or less.

12. The electrode mixture according to claim 1, wherein, The BET specific surface area of the solid electrolyte is 2.0 m 2 / g or more and 15.0 m 2 / g or less.

13. The electrode mixture according to claim 1 has a BET specific surface area of 0.5 m 2 / g or more and 5.0 m 2 / g or less.

14. The electrode mixture according to claim 1, wherein, The tapped density of the active material is 1.0 g / cm 3 or more and 3.0 g / cm 3 or less.

15. The electrode mixture according to claim 1, wherein, The tapped density of the solid electrolyte is 0.1 g / cm 3 or more and 1.0 g / cm 3 or less.

16. The electrode mixture according to claim 1, which further comprises a conductive additive.

17. An electrode, which is formed by applying the electrode mixture according to claim 1 on a current collector.

18. A battery, which comprises the electrode according to claim 17.

Images