Negative electrode material and battery using the same

Abstract

A negative electrode material according to the present disclosure comprises a negative electrode active material and a solid electrolyte. The negative electrode active material contains Li, Ti, M1 and O; and M1 represents at least one element that is selected from the group consisting of semimetal elements and metal elements other than Li and Ti. The solid electrolyte contains Li, M2 and X; M2 represents at least one element that is selected from the group consisting of semimetal elements and metal elements other than Li; and X represents at least one element that is selected from the group consisting of F, Cl, Br and I.

Description

[Technical Field]

[0001] The present disclosure relates to a negative electrode material and a battery using the same. [Background technology]

[0002] Lithium titanium oxide has been used as a negative electrode active material in lithium ion batteries. Its advantages include improved cycle characteristics, a flat potential, and a high potential relative to metallic lithium. Therefore, lithium titanium oxide is an excellent negative electrode active material.

[0003] Lithium titanium oxide has a problem in that lithium diffusion in the lithium titanium oxide is slow, making it difficult to charge and discharge at high rates. For example, Non-Patent Document 1 describes a Zr-doped Li4Ti5O 12 It is disclosed that the above is used as a negative electrode active material. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Lina Hou et al., “Zr-doped Li4Ti5O12 anode materials with high specific capacity for lithium-ion batteries”, Journal of Alloys and Compounds 774(2019) 38-45 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides new anode materials comprising oxides containing lithium and titanium suitable for use in solid-state batteries. [Means for solving the problem]

[0006] The negative electrode material of the present disclosure is a negative electrode active material; a solid electrolyte; Including, the negative electrode active material contains Li, Ti, M1, and O; M1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Ti, the solid electrolyte comprises Li, M2, and X; M2 is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is at least one selected from the group consisting of F, Cl, Br, and I. [Effects of the Invention]

[0007] The present disclosure provides new anode materials comprising oxides containing lithium and titanium suitable for use in solid-state batteries. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 shows a cross-sectional view of a battery 1000 according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Summary of one aspect of the present disclosure) The negative electrode material according to the first aspect of the present disclosure is a negative electrode active material; a solid electrolyte; Including, the negative electrode active material contains Li, Ti, M1, and O; M1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Ti, the solid electrolyte comprises Li, M2, and X; M2 is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is at least one selected from the group consisting of F, Cl, Br, and I.

[0010] The negative electrode active material included in the negative electrode material according to the first embodiment contains, in addition to Li, Ti, and O, at least one element M1 selected from the group consisting of metal elements and semimetal elements other than Li and Ti. By combining such a negative electrode active material with a solid electrolyte containing Li, M2, and X to form a negative electrode material, the negative electrode material according to the first embodiment can improve the charge / discharge rate of a battery. In other words, the first embodiment of the present disclosure provides a new negative electrode material comprising an oxide containing lithium and titanium, suitable for use in solid-state batteries.

[0011] In the second embodiment of the present disclosure, for example, in the negative electrode material according to the first embodiment, M1 may contain at least one selected from the group consisting of Zr, Cs, Ce, and Ca.

[0012] The negative electrode material according to the second embodiment can further improve the charge / discharge rate of the battery.

[0013] In the third embodiment of the present disclosure, for example, in the negative electrode material according to the second embodiment, M1 may include Zr.

[0014] The negative electrode material according to the third embodiment can further improve the charge / discharge rate of the battery.

[0015] In the fourth aspect of the present disclosure, for example, in the negative electrode material according to the third aspect, M1 may be Zr.

[0016] The negative electrode material according to the fourth aspect can further improve the charge / discharge rate of the battery.

[0017] In a fifth aspect of the present disclosure, for example, in the negative electrode material according to any one of the first to fourth aspects, the negative electrode active material may be represented by the following composition formula (1): Li4Ti 5-α M1 α O 12 ...Equation (1) Here, α satisfies 0<α≦0.3.

[0018] The negative electrode material according to the fifth embodiment can further improve the charge / discharge rate of the battery and further improve the charge / discharge efficiency of the battery.

[0019] In a sixth aspect of the present disclosure, for example, in the negative electrode material according to the fifth aspect, in the composition formula (1), α may satisfy 0<α≦0.2.

[0020] The negative electrode material according to the sixth embodiment can further improve the charge / discharge rate of the battery.

[0021] In the seventh aspect of the present disclosure, for example, in the negative electrode material according to the sixth aspect, in the composition formula (1), α may satisfy 0.01≦α≦0.1.

[0022] The negative electrode material according to the seventh embodiment can further improve the charge / discharge rate of the battery.

[0023] In an eighth aspect of the present disclosure, for example, in the negative electrode material according to any one of the first to fourth aspects, the negative electrode active material may be represented by the following composition formula (2). Li 4-β Ti5M1 β O 12 ...Equation (2) Here, β satisfies 0<β≦0.3.

[0024] The negative electrode material according to the eighth embodiment can further improve the charge / discharge rate of the battery and further improve the charge / discharge efficiency of the battery.

[0025] In a ninth aspect of the present disclosure, for example, in the negative electrode material according to the eighth aspect, β in the composition formula (2) may satisfy 0<β≦0.1.

[0026] The negative electrode material according to the ninth embodiment can further improve the charge / discharge rate of the battery.

[0027] In a tenth aspect of the present disclosure, for example, in the negative electrode material according to the ninth aspect, in the composition formula (2), β may satisfy 0.01≦β≦0.06.

[0028] The negative electrode material according to the tenth aspect can further improve the charge / discharge rate of the battery.

[0029] In an eleventh aspect of the present disclosure, for example, in the negative electrode material according to any one of the first to tenth aspects, M2 may include Y.

[0030] The negative electrode material according to the eleventh embodiment can further improve the charge / discharge rate of the battery.

[0031] In a twelfth aspect of the present disclosure, for example, in the negative electrode material according to any one of the first to eleventh aspects, X may be at least one selected from the group consisting of Cl, Br, and I.

[0032] The negative electrode material according to the twelfth embodiment can further improve the charge / discharge rate of the battery.

[0033] In a thirteenth aspect of the present disclosure, for example, in the negative electrode material according to any one of the first to twelfth aspects, the solid electrolyte may be substantially free of sulfur.

[0034] The negative electrode material according to the thirteenth aspect has excellent safety.

[0035] A battery according to a fourteenth aspect of the present disclosure comprises: a positive electrode layer; a negative electrode layer; an electrolyte layer located between the positive electrode layer and the negative electrode layer; Equipped with The negative electrode layer includes the negative electrode material according to any one of the first to thirteenth embodiments.

[0036] The battery according to the fourteenth embodiment has an improved charge / discharge rate.

[0037] (Embodiments of the present disclosure) Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

[0038] (First embodiment) The negative electrode material according to the first embodiment includes a negative electrode active material and a solid electrolyte. The negative electrode active material includes Li, Ti, M1, and O, where M1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Ti. The solid electrolyte includes Li, M2, and X, where M2 is at least one selected from the group consisting of metal elements and metalloid elements other than Li, and X is at least one selected from the group consisting of F, Cl, Br, and I.

[0039] The negative electrode active material contained in the negative electrode material according to the first embodiment contains, in addition to Li, Ti, and O, at least one element M1 selected from the group consisting of metal elements and semimetal elements other than Li and Ti. By combining such a negative electrode active material with a solid electrolyte containing Li, M2, and X to form a negative electrode material, the negative electrode material can improve the charge / discharge rate of a battery. In other words, the negative electrode material according to the first embodiment is a new negative electrode material containing an oxide containing lithium and titanium, suitable for use in solid-state batteries.

[0040] As used herein, the term "metal element" means (i) all elements in groups 1 to 12 of the periodic table (excluding hydrogen), and (ii) all elements in groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se). In other words, metal elements are a group of elements that can become cations when forming inorganic compounds with halogen compounds.

[0041] The term "metalloid elements" as used herein refers to B, Si, Ge, As, Sb, and Te.

[0042] In order to further improve the charge / discharge rate of the battery, in the negative electrode active material in the negative electrode material according to the first embodiment, M1 may contain at least one selected from the group consisting of Zr (i.e., zirconium), Cs (i.e., cesium), Ce (i.e., cerium), and Ca (i.e., calcium).

[0043] According to the above configuration, the ionic conductivity of the negative electrode active material can be further improved, and the negative electrode material according to the first embodiment can thereby further improve the charge / discharge rate of the battery.

[0044] In order to further improve the charge / discharge rate of the battery, M1 in the negative electrode active material in the negative electrode material according to the first embodiment may contain Zr. That is, the negative electrode active material in the negative electrode material according to the first embodiment may contain Zr as the metal element M1.

[0045] According to the above configuration, the ionic conductivity of the negative electrode active material can be further improved, and the negative electrode material according to the first embodiment can thereby further improve the charge / discharge rate of the battery.

[0046] In order to further improve the charge / discharge rate of the battery and further improve the charge / discharge efficiency of the battery, the negative electrode active material contained in the negative electrode active material according to the first embodiment may be represented by the following composition formula (1). Li4Ti 5-α Zr α O 12 ...Equation (1) Here, α satisfies 0<α≦0.3.

[0047] In order to further improve the charge / discharge efficiency of the battery, in composition formula (1), α may satisfy the relationship 0<α≦0.2.

[0048] In order to further improve the charge / discharge efficiency of the battery, in composition formula (1), α may satisfy the relationship 0.01≦α≦0.1.

[0049] In order to further improve the charge / discharge rate of the battery and further improve the charge / discharge efficiency of the battery, the negative electrode active material contained in the negative electrode active material according to the first embodiment may be represented by the following composition formula (2). Li 4-β Ti5M1 β O 12 ...Equation (2) Here, β satisfies 0<β≦0.3.

[0050] In order to further improve the charge / discharge efficiency of the battery, β in composition formula (2) may satisfy the relationship 0<β≦0.1.

[0051] In order to further improve the charge / discharge efficiency of the battery, β in composition formula (2) may satisfy the relationship 0.01≦β≦0.06.

[0052] As an example of a negative electrode active material containing Zr, Li a1 Ti b1 Zr c1 Me1 d1 O e1 The compound may be a compound represented by the following composition formula: where a1+4b1+4c1+m1d1=2e1, c1>0, Me1 is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Y, and m1 is the valence of Me1. As Me1, 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 may be used.

[0053] As described above, the solid electrolyte contained in the negative electrode material according to the first embodiment contains Li, M2, and X. Hereinafter, the solid electrolyte contained in the negative electrode material according to the first embodiment and containing Li, M2, and X will be referred to as the first solid electrolyte.

[0054] The first solid electrolyte may consist essentially of Li, M2, and X. "The first solid electrolyte consists essentially of Li, M2, and X" means that in the first solid electrolyte, the ratio of the total amount of substance of Li, M2, and X to the total amount of substance of all elements constituting the solid electrolyte (i.e., molar fraction) is 90% or more. As an example, the ratio (i.e., molar fraction) may be 95% or more. The first solid electrolyte may consist only of Li, M2, and X.

[0055] To increase the ionic conductivity and improve the charge / discharge rate of the battery, M2 may contain at least one element selected from the group consisting of Group 1 elements, Group 2 elements, Group 3 elements, Group 4 elements, and lanthanoid elements. To increase the ionic conductivity and improve the charge / discharge rate of the battery, M2 may contain at least one element selected from the group consisting of Group 5 elements, Group 12 elements, Group 13 elements, and Group 14 elements.

[0056] Examples of Group 1 elements are Na, K, Rb, or Cs. Examples of Group 2 elements are Mg, Ca, Sr, or Ba. Examples of Group 3 elements are Sc or Y. Examples of Group 4 elements are Ti, Zr, or Hf. Examples of Lanthanide elements are La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu. Examples of Group 5 elements are Nb or Ta. An example of Group 12 elements is Zn. An example of Group 13 elements is Al, Ga, or In. An example of Group 14 elements is Sn.

[0057] In order to increase the ionic conductivity and improve the charge / discharge rate of the battery, M2 may contain at least one element selected from the group consisting of Na, K, Mg, Ca, Sr, Ba, Sc, Y, Zr, Hf, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0058] In order to increase the ionic conductivity and improve the charge / discharge rate of the battery, M2 may contain at least one element selected from the group consisting of Mg, Ca, Sr, Y, Sm, Gd, Dy, and Hf.

[0059] In order to further improve the charge / discharge rate of the battery, M2 in the first solid electrolyte may contain Y (i.e., yttrium). That is, in the first embodiment, the first solid electrolyte may contain Y as the metal element M2.

[0060] X may contain at least one element selected from the group consisting of Cl, Br, and I in order to further improve the charge / discharge rate of the battery.

[0061] In order to further improve the charge / discharge rate of the battery, X may contain at least two elements selected from the group consisting of Cl, Br, and I.

[0062] X1 may include Cl, Br, and I to further improve the charge / discharge rate of the battery.

[0063] The first solid electrolyte may be a material represented by the following composition formula (3). Li α M2 β X γ ...Equation (3) Here, α, β, and γ are each independently a value greater than 0. Note that M2 and X are as defined above.

[0064] The terms "metalloid element" and "metal element" used in this specification are as defined above. That is, metal elements are a group of elements that can become cations when forming the inorganic compounds in the above composition formulas (1), (2), and (3).

[0065] According to the above configuration, the ionic conductivity of the first solid electrolyte can be further improved, thereby improving the charge / discharge rate of the battery.

[0066] The first solid electrolyte containing Y is, for example, Li a2 Me2 b2 Y c2 X6, where a2 + m2 b2 + 3 c2 = 6, c2 > 0, Me2 is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Y, and m2 is the valence of Me2. Me2 may be 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.

[0067] The shape of the first solid electrolyte is not limited. The shape of the first solid electrolyte may be, for example, needle-like, spherical, oval-spherical, or fibrous. For example, the first solid electrolyte may be particulate. The first solid electrolyte may be formed into a pellet or plate shape.

[0068] For example, when the first solid electrolyte is particulate (e.g., spherical) to further increase ionic conductivity and achieve good dispersion with other materials such as the negative electrode active material, the first solid electrolyte may have a median diameter of 0.1 μm or more and 100 μm or less. The median diameter refers to the particle size at which the cumulative volume in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution can be measured using a laser diffraction measurement device or an image analyzer.

[0069] The median diameter may be 0.5 μm or more and 10 μm or less, so that the first solid electrolyte has high ionic conductivity.

[0070] The first solid electrolyte is, for example, substantially free of sulfur. The term "the first solid electrolyte is substantially free of sulfur" means that the first solid electrolyte does not contain sulfur as a constituent element, except for sulfur inevitably mixed in as an impurity. In this case, the amount of sulfur mixed in the first solid electrolyte as an impurity is, for example, 1 mol % or less. The first solid electrolyte may not contain sulfur. When the first solid electrolyte is free of sulfur, the first solid electrolyte does not generate hydrogen sulfide even when exposed to the atmosphere, and therefore is highly safe.

[0071] The negative electrode material according to the first embodiment may further include another solid electrolyte having a different composition or crystal structure from the first solid electrolyte. In this case, the mass of the first solid electrolyte relative to the total mass of the solid electrolytes included in the negative electrode material may be in the range of 5 mass% to 95 mass%. Examples of solid electrolytes having a different composition from the first solid electrolyte include sulfide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes, and complex hydride solid electrolytes. Examples of sulfide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes, and complex hydride solid electrolytes are the same as the examples of solid electrolytes that can be used in the positive electrode layer 101 according to the second embodiment described below.

[0072] (Second embodiment) A second embodiment of the present disclosure will be described below. The matters described in the first embodiment may be omitted.

[0073] In the second embodiment, a battery including a negative electrode layer using the negative electrode material according to the first embodiment will be described.

[0074] FIG. 1 shows a cross-sectional view of a battery 1000 according to a second embodiment.

[0075] The battery 1000 according to the second embodiment includes a positive electrode layer 101, an electrolyte layer 102, and a negative electrode layer 103. The electrolyte layer 102 is disposed between the positive electrode layer 101 and the negative electrode layer 103. The negative electrode layer 103 includes the negative electrode material according to the first embodiment.

[0076] With the above configuration, the battery 1000 according to the second embodiment can improve the charge and discharge speed.

[0077] An example of the battery 1000 according to this embodiment is an all-solid-state battery. The all-solid-state battery may be a primary battery or a secondary battery.

[0078] Each component of the battery 1000 of this embodiment will be described in more detail below.

[0079] (negative electrode layer) As described above, in the second embodiment, the negative electrode layer 103 includes the negative electrode material according to the first embodiment. The negative electrode material is as described in the first embodiment.

[0080] The negative electrode layer 103 may include negative electrode active material particles 104 and first solid electrolyte particles 105, as shown in FIG.

[0081] The median diameter of the negative electrode active material particles 104 may be 0.1 μm or more and 100 μm or less. When the negative electrode active material particles 104 have a median diameter of 0.1 μm or more, the negative electrode active material particles 104 and the first solid electrolyte particles 105 are well dispersed in the negative electrode layer 103. This improves the charge / discharge characteristics of the battery 1000. When the negative electrode active material particles 104 have a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material particles 104 improves. This allows the battery 1000 to operate at high power.

[0082] The negative electrode active material particles 104 may have a larger median diameter than the first solid electrolyte particles 105. This improves the dispersion state of the negative electrode active material particles 104 and the first solid electrolyte particles 105 in the negative electrode layer 103.

[0083] In the negative electrode layer 103 of this embodiment, the first solid electrolyte particles 105 and the negative electrode active material particles 104 may be in contact with each other, as shown in FIG.

[0084] Furthermore, the negative electrode layer 103 in this embodiment may include a plurality of first solid electrolyte particles 105 and a plurality of negative electrode active material particles 104.

[0085] In addition, in the negative electrode layer 103 of this embodiment, the content of the first solid electrolyte particles 105 may be the same as or different from the content of the negative electrode active material particles 104.

[0086] In the negative electrode layer 103, the volume ratio Vn, which represents the volume of the negative electrode active material particles relative to the total volume of the negative electrode active material particles 104 and the first solid electrolyte particles 105, may be 0.3 or more and 0.95 or less. When the volume ratio Vn is 0.3 or more, the energy density of the battery 1000 can be improved. On the other hand, when the volume ratio Vn is 0.95 or less, the output of the battery 1000 can be improved.

[0087] The thickness of the negative electrode layer 103 may be 10 μm or more and 500 μm or less.

[0088] When the thickness of the negative electrode layer 103 is 10 μm or more, the battery 1000 can ensure a sufficient energy density. When the thickness of the negative electrode layer 103 is 500 μm or less, the output of the battery 1000 can be improved.

[0089] (positive electrode layer) The positive electrode layer 101 contains a material that can absorb and release metal ions (for example, lithium ions). The positive electrode layer 101 may also contain a positive electrode active material.

[0090] Examples of the positive electrode active material include a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion material, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxyfluoride, a transition metal oxysulfide, or a transition metal oxynitride. Examples of the lithium-containing transition metal oxide include Li(NiCoAl)O2, Li(NiCoMn)O2, or LiCoO2. 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.

[0091] To improve charge / discharge capacity, the positive electrode active material may be lithium nickel cobalt manganese oxide.

[0092] The positive electrode layer 101 may contain a solid electrolyte. According to the above configuration, the lithium ion conductivity inside the positive electrode layer 101 is increased, and high-power operation becomes possible.

[0093] Examples of the solid electrolyte contained in the positive electrode layer 101 include a halide solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte.

[0094] As the halide solid electrolyte, for example, the materials exemplified above as the first solid electrolyte may be used.

[0095] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 , etc. can be used. Furthermore, LiX', Li2O, M'Oq, LipM'Oq, etc. may be added to these. Here, X' is at least one selected from the group consisting of F, Cl, Br, and I. M' is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. p and q are natural numbers.

[0096] Examples of oxide solid electrolytes include: (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutes; (ii) Perovskite-type solid electrolytes such as (LaLi)TiO3; (iii) Li 14 ZnGeO 16 LISICON-type solid electrolytes such as Li4SiO4, LiGeO4, or elemental substitutions thereof; (iv) Li7La3Zr2O 12or a garnet-type solid electrolyte such as an element substitution product thereof; (v) Li3PO4 or its N-substituted derivatives (vi) LiN or its H-substituted derivatives, or (vii) Glass or glass ceramics based on Li-BO compounds such as LiBO2 and Li3BO3, to which Li2SO4, Li2CO3, etc. have been added And so on.

[0097] An example of the polymer solid electrolyte is a compound of a polymer compound and a lithium salt.

[0098] The polymer compound may have an ethylene oxide structure. A polymer compound having an ethylene oxide structure can contain a large amount of lithium salt, and therefore can further increase ionic conductivity.

[0099] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF) , LiN(SOCF)(SOCF), or LiC(SOCF). One lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0100] Examples of complex hydride solid electrolytes are LiBH4-LiI or LiBH4-P2S5.

[0101] The median diameter of the positive electrode active material particles may be 0.1 μm or more and 100 μm or less. When the positive electrode active material particles have a median diameter of 0.1 μm or more, the positive electrode active material particles and solid electrolyte particles are well dispersed in the positive electrode layer 101. This improves the charge / discharge characteristics of the battery 1000. When the positive electrode active material particles have a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material particles improves. This allows the battery 1000 to operate at high power.

[0102] The median diameter of the positive electrode active material particles may be larger than the median diameter of the solid electrolyte particles, thereby enabling the positive electrode active material particles and the solid electrolyte particles to be well dispersed.

[0103] In the positive electrode layer 101, the volume ratio Vp, which represents the volume of the positive electrode active material particles relative to the total volume of the positive electrode active material particles and the solid electrolyte particles, may be 0.3 or more and 0.95 or less. When the volume ratio Vp is 0.3 or more, the energy density of the battery 1000 can be improved. On the other hand, when the volume ratio Vp is 0.95 or less, the output of the battery 1000 can be improved.

[0104] The thickness of the positive electrode layer 101 may be 10 μm or more and 500 μm or less.

[0105] When the thickness of the positive electrode layer 101 is 10 μm or more, the battery 1000 can ensure a sufficient energy density. When the thickness of the positive electrode layer 101 is 500 μm or less, the output of the battery 1000 can be improved.

[0106] The positive electrode active material may be coated. As the coating material, a material with low electronic conductivity can be used. As the coating material, an oxide material, an oxide solid electrolyte, or the like can be used.

[0107] Examples of oxide materials are SiO2, Al2O3, TiO2, B2O3, Nb2O5, WO3, or ZrO2.

[0108] Examples of oxide solid electrolytes include: (i) Li-Nb-O compounds such as LiNbO3, (ii) Li-BO compounds such as LiBO2 and Li3BO3; (iii) Li-Al-O compounds such as LiAlO2; (iv) Li-Si-O compounds such as Li4SiO4; (v) Li-SO compounds such as Li2SO4, (vi) LiTiO 12 Li-Ti-O compounds such as (vii) Li-Zr-O compounds such as Li2ZrO3; (viii) Li-Mo-O compounds such as Li2MoO3; (ix) Li-VO compounds such as LiV2O5, or (x) Li-WO compounds such as Li2WO4 is.

[0109] Oxide solid electrolytes have high ionic conductivity and high potential stability, and therefore, by using oxide solid electrolytes, charge / discharge efficiency can be further improved.

[0110] (electrolyte layer) The electrolyte layer 102 includes a solid electrolyte. The solid electrolyte included in the electrolyte layer 102 may be any of the above-described materials (e.g., halide solid electrolytes, sulfide solid electrolytes, oxide solid electrolytes, polymer solid electrolytes, complex hydride solid electrolytes, etc.).

[0111] The electrolyte layer 102 may contain two or more of the materials listed as solid electrolyte materials. For example, the electrolyte layer 102 may contain a first solid electrolyte and a sulfide solid electrolyte.

[0112] The thickness of the electrolyte layer 102 may be 1 μm or more and 300 μm or less.

[0113] When the electrolyte layer 102 has a thickness of 1 μm or more, it is difficult for a short circuit to occur between the positive electrode layer 101 and the negative electrode layer 103. When the electrolyte layer 102 has a thickness of 300 μm or less, the battery 1000 can operate at a high output.

[0114] At least one selected from the group consisting of the positive electrode layer 101, the electrolyte layer 102, and the negative electrode layer 103 may contain a binder to improve adhesion between particles. The binder is used to improve the binding of the materials that constitute the electrode.

[0115] Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose.

[0116] In addition, as the binder, a copolymer of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene can be used.

[0117] Also, two or more binders may be used.

[0118] At least one selected from the group consisting of the positive electrode layer 101 and the negative electrode layer 103 may contain a conductive additive for the purpose of increasing electronic conductivity.

[0119] Examples of the conductive additive include: (i) graphites such as natural or synthetic graphite; (ii) carbon blacks such as acetylene black or ketjen black; (iii) conductive fibers such as carbon or metal fibers; (iv) fluorocarbons, (v) metal powders such as aluminum; (vi) conductive whiskers such as zinc oxide or potassium titanate; (vii) a conductive metal oxide, such as titanium oxide, or (viii) Conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene To reduce costs, the above-mentioned conductive additive (i) or (ii) may be used.

[0120] Examples of the shape of the battery according to this embodiment include coin type, cylindrical type, square type, sheet type, button type, flat type, and laminate type. [Example]

[0121] Hereinafter, the present disclosure will be described in detail using examples and comparative examples.

[0122] [Example 1] (Preparation of first solid electrolyte) In a dry argon atmosphere with a dew point of -60°C or less, raw material powders LiBr, YBr3, LiCl, and YCl3 were weighed out so that the molar ratio of Li:Y:Br:Cl was 3:1:2:4. These were pulverized and mixed in a mortar. Then, the mixture was milled at 600 rpm for 25 hours using a planetary ball mill (Fritsch, Model P-7). As a result, a powder of Li3YBr2Cl4, which was the first solid electrolyte of Example 1, was obtained.

[0123] (Evaluation of the composition of the first solid electrolyte) The composition of the first solid electrolyte of Example 1 was evaluated using ICP (Inductive Coupled Plasma) emission spectroscopy. As a result, the deviation of Li / Y from the charged composition was within 3%. In other words, in Example 1, the charged composition using the planetary ball mill and the composition of the obtained first solid electrolyte were almost the same.

[0124] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and ZrO(NO3)2 were mixed in a molar ratio of Li2CO3:TiO2:ZrO(NO3)2 = 29.58:70.28:0.14. Then, a planetary ball mill (Fritsch, P-7 type) was used to perform milling at 150 rpm for 1 hour. The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti, the negative electrode active material of Example 1. 4.99 Zr 0.01 O 12 A powder of 1000 ppm was obtained.

[0125] (Production of negative electrode materials) In a dry argon atmosphere having a dew point of −60° C. or less, the first solid electrolyte of Example 1, Li3YBr2Cl4, and the negative electrode active material, Li4Ti, were mixed. 4.99 Zr 0.01 O 12 and VGCF (Vapor Grown Carbon Fiber) as a conductive additive, Li3YBr2Cl4:Li4Ti 4.99 Zr 0.01 O 12 The materials were weighed in a mass ratio of VGCF:CO₂ = 56.6:39:4.4 and mixed in an agate mortar to prepare the negative electrode material of Example 1. VGCF is a registered trademark of Showa Denko K.K.

[0126] (Battery construction) In an insulating tube having an inner diameter of 9.5 mm, 20 mg of the negative electrode material of Example 1 and 80 mg of a sulfide solid electrolyte material Li6PS5Cl manufactured by MSE were stacked in this order. A pressure of 360 MPa was applied to the resulting stack, producing a negative electrode layer formed from the negative electrode material of Example 1 and an electrolyte layer formed from Li6PS5Cl. Next, metal In (thickness 200 μm), metal Li (thickness 300 μm), and metal In (thickness 200 μm) were stacked in this order on the side of the electrolyte layer opposite to the side in contact with the negative electrode layer. A pressure of 80 MPa was applied to the resulting stack, forming a positive electrode layer.

[0127] As a result, a laminate consisting of a positive electrode layer, an electrolyte layer, and a negative electrode layer was obtained. Next, current collectors made of stainless steel were attached to the top and bottom of the laminate, i.e., the positive electrode layer and the negative electrode layer, and current collecting leads were attached to the current collectors. Finally, an insulating ferrule was used to isolate the inside of the insulating tube from the outside atmosphere and seal the inside of the tube. In this way, a battery according to Example 1 was obtained.

[0128] [Example 2] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and ZrO(NO3)2 were mixed in a molar ratio of Li2CO3:TiO2:ZrO(NO3)2 = 27.83:71.34:0.83. Then, a planetary ball mill (Fritsch, P-7 type) was used to mill the powder at 150 rpm for 1 hour. The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti, the negative electrode active material of Example 2. 4.98 Zr 0.02 O 12 A powder of 1000 ppm was obtained.

[0129] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0130] [Example 3] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and ZrO(NO3)2 were mixed in a molar ratio of Li2CO3:TiO2:ZrO(NO3)2 = 27.53:70.01:2.46. Then, using a planetary ball mill (Fritsch, P-7 model), milling was performed for 1 hour at 150 rpm. The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti, the negative electrode active material of Example 3. 4.94 Zr 0.06 O 12 A powder of 1000 ppm was obtained.

[0131] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0132] [Example 4] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and ZrO(NO3)2 were mixed in a molar ratio of Li2CO3:TiO2:ZrO(NO3)2 = 27.23:68.71:4.06. Then, using a planetary ball mill (Fritsch, P-7 model), milling was performed for 1 hour at 150 rpm. The resulting mixed powder was then heat-treated at 900 °C for 12 hours. This produced Li4Ti, the negative electrode active material of Example 4. 4.9 Zr 0.1 O 12 A powder of 1000 ppm was obtained.

[0133] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0134] [Example 5] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and ZrO(NO3)2 were mixed in a molar ratio of Li2CO3:TiO2:ZrO(NO3)2 = 26.53:65.56:7.91. Then, using a planetary ball mill (Fritsch, P-7 model), milling was performed for 1 hour at 150 rpm. The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti, the negative electrode active material of Example 5. 4.8 Zr 0.2 O 12 A powder of 1000 ppm was obtained.

[0135] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0136] [Example 6] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and Cs2(CO3) were mixed in a molar ratio of Li2CO3:TiO2:Cs2(CO3) = 28.43:71.43:0.14. Then, a planetary ball mill (Fritsch, P-7 type) was used to mill the powder at 150 rpm for 1 hour. The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced the negative electrode active material Li2CO3, which is used in Example 6. 3.98 Ti5Cs 0.02 O 12 A powder of 1000 ppm was obtained.

[0137] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0138] [Example 7] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and Cs2(CO3) were mixed in a molar ratio of Li2CO3:TiO2:Cs2(CO3) = 27.86:71.43:0.71, and milled at 150 rpm for 1 hour using a planetary ball mill (Fritsch, P-7 model). The resulting mixed powder was then heat-treated at 900°C for 12 hours. 3.9 Ti5Cs 0.1 O 12 A powder of 1000 ppm was obtained.

[0139] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0140] [Example 8] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and Ce(NO3)3·6H2O were mixed in a molar ratio of Li2CO3:TiO2:Ce(NO3)3 = 28.57:71.29:0.14, and milled at 150 rpm for 1 hour using a planetary ball mill (Fritsch, P-7 model). The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti 4.99 Ce 0.01 O 12 A powder of 1000 ppm was obtained.

[0141] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0142] [Example 9] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and Ce(NO3)3·6H2O were mixed in a molar ratio of Li2CO3:TiO2:Ce(NO3)3 = 28.57:71.14:0.29, and milled at 150 rpm for 1 hour using a planetary ball mill (Fritsch, P-7 model). The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti 4.98 Ce 0.02 O 12 A powder of 1000 ppm was obtained.

[0143] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0144] [Example 10] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and Ce(NO3)3·6H2O were mixed in a molar ratio of Li2CO3:TiO2:Ce(NO3)3 = 28.57:70.57:0.86, and milled at 150 rpm for 1 hour using a planetary ball mill (Fritsch, P-7 model). The resulting mixed powder was then heat-treated at 900°C for 12 hours. This produced Li4Ti 4.94 Ce 0.06 O 12 A powder of 1000 ppm was obtained.

[0145] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0146] [Example 11] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and CaO were mixed in a molar ratio of Li2CO3:TiO2:CaO = 28.39:71.32:0.29, and milled for 1 hour at 150 rpm using a planetary ball mill (Fritsch, P-7 model). The resulting mixed powder was then heat-treated at 900°C for 12 hours. 3.98 Ti5Ca 0.02 O 12 A powder of 1000 ppm was obtained.

[0147] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0148] [Example 12] (Preparation of negative electrode active material) The raw material powders Li2CO3, TiO2, and CaO were mixed in a molar ratio of Li2CO3:TiO2:CaO = 27.66:70.92:1.42, and milled at 150 rpm for 1 hour using a planetary ball mill (Fritsch, P-7 model). The resulting mixed powder was then heat-treated at 900°C for 12 hours. 3.9 Ti5Ca 0.1 O 12 A powder of 1000 ppm was obtained.

[0149] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0150] [Comparative Example 1] (Preparation of negative electrode active material) The raw material powders Li2CO3 and TiO2 were mixed in a molar ratio of Li2CO3:TiO2 = 27.98:72.02. Then, a planetary ball mill (Fritsch, P-7 type) was used to perform milling at 150 rpm for 1 hour. The resulting mixed powder was then heat-treated at 900 °C for 12 hours. This produced Li4Ti5O, the negative electrode active material of Comparative Example 1. 12 A powder of 1000 ppm was obtained.

[0151] The procedure was the same as in Example 1 except for the preparation of the negative electrode active material.

[0152] Comparative Example 2 (Production of negative electrode materials) In a dry argon atmosphere with a dew point of -60°C or less, a sulfide solid electrolyte material Li6PS5Cl manufactured by MSE and a negative electrode active material Li4Ti5O manufactured by the same method as in Comparative Example 1 were 12 and the conductive additive VGCF, Li6PS5Cl:Li4Ti5O 12 The materials were weighed in a mass ratio of VGCF: 56.6:39:4.4, and mixed in an agate mortar to prepare a negative electrode material.

[0153] The procedure was the same as in Example 1 except for the negative electrode active material and the preparation of the negative electrode active material.

[0154] Comparative Example 3 (Production of negative electrode materials) In a dry argon atmosphere with a dew point of -60°C or less, a sulfide solid electrolyte material Li6PS5Cl manufactured by MSE and a negative electrode active material Li4Ti manufactured by the same method as in Example 2 were mixed. 4.98 Zr 0.02 O 12 and the conductive additive VGCF, Li6PS5Cl:Li4Ti 4.98 Zr 0.02 O 12 The materials were weighed in a mass ratio of VGCF: 56.6:39:4.4, and mixed in an agate mortar to prepare a negative electrode material.

[0155] The procedure was the same as in Example 1 except for the negative electrode active material and the preparation of the negative electrode active material.

[0156] Comparative Example 4 (Production of negative electrode materials) In a dry argon atmosphere with a dew point of -60°C or less, a sulfide solid electrolyte material Li6PS5Cl manufactured by MSE and a negative electrode active material Li4Ti manufactured by the same method as in Example 4 were mixed. 4.9 Zr 0.1 O 12 and the conductive additive VGCF, Li6PS5Cl:Li4Ti 4.9 Zr 0.1 O 12 The components were weighed in a weight ratio of VGCF:CO₂ = 56.6:39:4.4, and mixed in an agate mortar to prepare a negative electrode material.

[0157] The procedure was the same as in Example 1 except for the negative electrode active material and the preparation of the negative electrode active material.

[0158] [Charge / discharge test] The charge / discharge tests of the batteries in all the examples and comparative examples were carried out as follows.

[0159] The battery was placed in a thermostatic chamber at 25°C. It was discharged (essentially charged) at a constant current of 1387 μA, equivalent to a 1C rate, until the potential relative to the metallic Li-In alloy reached 0.38 V. The battery was then left open for 20 minutes. The positive electrode potential recovered after 20 minutes of open-circuiting. It was then discharged at a constant current of 69 μA until the potential relative to the metallic Li-In alloy reached 0.38 V.

[0160] Based on the above results, the ratio of the capacity at a current value of 1387 μA to the total capacity determined by constant current discharge at a current value of 1387 μA and subsequent constant current discharge at a current value of 69 μA (hereinafter referred to as "1C capacity ratio") was calculated. The 1C capacity ratio of the battery was calculated using the following formula. The 1C capacity ratio indicates the rate characteristics of the battery. A battery with poor rate characteristics will have a low 1C capacity ratio, and a battery with excellent rate characteristics will have a high 1C capacity ratio.

[0161] 1C capacity ratio (%) = capacity at current value 1387 μA ÷ (capacity at current value 1387 μA + capacity at current value 69 μA) × 100

[0162] The results are shown in Table 1 below.

[0163] [Table 1]

[0164] As shown in Table 1, the batteries of Examples 1 to 12, which had a negative electrode layer containing a negative electrode material including a negative electrode active material containing Li, Ti, M1, and O and a solid electrolyte containing Li, M2, and X, achieved a higher 1C capacity percentage than the battery of Comparative Example 1. In Examples 1 to 12, the negative electrode active material contained Zr, Cs, Ce, or Ca as M1, and the first solid electrolyte contained Y as M2. The reason that the negative electrode materials of Examples 1 to 12 were able to achieve a high 1C capacity percentage is thought to be due to an improved transport rate of lithium ions within the negative electrode active material.

[0165] From the results of Examples 1 to 5, a higher 1C capacity ratio was obtained when α, the composition ratio of M1 (i.e., Zr in this case) in the composition formula (1), was 0.01 or more and 0.1 or less. This is thought to be due to a further improvement in the transport rate of lithium ions within the negative electrode active material. On the other hand, even in systems in which M1 (i.e., Zr in this case) was present in the negative electrode active material, the 1C capacity ratio decreased when Li6PS5Cl was used as the first solid electrolyte. This is presumably due to the formation of a layer that inhibits lithium ion transport at the interface between the negative electrode active material and the first solid electrolyte due to Zr-sulfur bonding. [Industrial Applicability]

[0166] The battery of the present disclosure can be used, for example, as an all-solid-state lithium-ion secondary battery. [Explanation of symbols]

[0167] 1000 batteries 101 Positive electrode layer 102 Electrolyte layer 103 Negative electrode layer 104 Negative electrode active material particles 105 Solid electrolyte particles

Claims

1. a negative electrode active material; a solid electrolyte; Including, The negative electrode active material is represented by the following composition formula (1) or composition formula (2): Li 4 Ti 5-α M1 α O 12 ...Formula (1) Li 4-β Ti 5 M1 β O 12 ...Formula (2) where: In the composition formula (1), α satisfies 0.01≦α≦0.1, In the composition formula (2), β satisfies 0.01≦β≦0.1, In the above composition formulas (1) and (2), M1 is at least one selected from the group consisting of Cs, Ce, and Ca, The solid electrolyte is represented by Li 3 YX 6 , X is at least one selected from the group consisting of Cl and Br. Negative electrode material.

2. In the composition formula (2), β satisfies 0.01≦β≦0.

06. The negative electrode material according to claim 1 .

3. The solid electrolyte is substantially free of sulfur. The negative electrode material according to claim 1 or 2.

4. a positive electrode layer; a negative electrode layer; an electrolyte layer located between the positive electrode layer and the negative electrode layer; Equipped with The negative electrode layer comprises the negative electrode material according to any one of claims 1 to 3. battery.

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