JP7293051B2 - solid electrolyte materials, electrodes, batteries, battery packs, and vehicles - Google Patents

Description

Embodiments of the present invention relate to solid electrolyte materials, electrodes, batteries, battery packs, and vehicles.

In recent years, lithium-ion secondary batteries with high energy densities have attracted a great deal of attention for their wide range of uses, from use in small electronic devices to large-scale uses such as hybrid electric vehicles, electric vehicles, and stationary power sources for power storage. Among them, lithium-ion secondary batteries using inorganic solid electrolytes are expected to be safe batteries because there is no fear of organic electrolyte leakage or gas generation. In addition, compared with batteries using liquid electrolytes, lithium batteries using solid electrolytes are less likely to undergo side reactions other than battery reactions, and thus are expected to have a longer life. Furthermore, in all-solid-state batteries using an inorganic solid electrolyte, the manufacturing cost can be reduced because the electrode and the electrolyte are easily laminated. At the same time, when an inorganic solid electrolyte is used, a bipolar battery configuration is also possible. As a result, a higher energy density can be expected compared to batteries using conventional liquid electrolytes. However, in a lithium ion battery having a particularly high electromotive force, the positive electrode is a highly oxidizing substance and the negative electrode is a highly reducing substance. Therefore, even if these substances and the solid electrolyte are brought into close contact with each other, they must be stable. In addition, it is a practically important factor that the constituent elements are inexpensive.

In recent years, lithium lanthanum zirconate-based compounds and perovskite oxides, which have high lithium ion conductivity and can be easily obtained by solid-phase reactions in the atmosphere, have attracted attention. A typical _{example of} these materials is _{Li7La3Zr2O12 .} This compound is known to exhibit a high lithium ion conductivity of 5×10 ⁻⁴ S/cm or higher at room temperature, which is top class among oxide solid electrolytes.

International publication WO2013/140574 JP 2018-49701

Y. Kawakami et al., Solid State Ionics, Volume 110, Issues 3-4, 2 July 1998, Pages 187-192 Hui Xie et al., RSC Advances, 2011, 1, 1728-1731

An object of the present invention is to provide a solid electrolyte material having high ionic conductivity and excellent reduction resistance, an electrode, a battery and a battery pack containing this solid electrolyte material, and a vehicle equipped with this battery pack. and

According to the embodiment, a solid electrolyte material containing an oxide containing an octahedral coordination structure containing a metal element M and oxygen atoms arranged in the center of the metal element M is provided. The metal element M includes the metal element Mα, or the metal element Mα and the metal element Mβ. The metal element Mα contains Nb and Ta. The metal element Mβ includes at least one selected from the group consisting of Ti, Zr, Ga, Ge, Si, Fe, and P. The mass ratio α _Ta /α _Nb between the mass α _Nb of Nb and the mass α _Ta of Ta is within the range of 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ . The crystal structure of the oxide includes at least one selected from the group consisting of a perovskite structure and a NASICON structure. The oxide having a perovskite structure is represented by the general formula A(Mα _1-w Mβ _w )O _{3 ,} where w is in the range of 0≦w<1, and contains Li and vacancies at the A site. The NASICON structure includes at least one selected from the group consisting of a rhombohedral structure and a monoclinic structure. The oxide having the NASICON structure is represented by the general formula Li _x Mα _y (Mβ _1-z D _z )(PO ₄ ) ₃ , where D is at least one selected from the group consisting of Ca, Sr and Ba. Yes, x is in the range 0<x≦2, y is in the range 0<y≦1, and z is in the range 0≦z≦1.

According to another embodiment, there is provided an electrode comprising the solid electrolyte material according to the above embodiments.

According to yet another embodiment, a battery is provided that includes a positive electrode layer, a negative electrode layer, and a Li-conducting layer. The positive electrode layer is capable of intercalation/deintercalation of lithium ions. The negative electrode layer is capable of intercalation/deintercalation of lithium ions. The Li conductive layer is capable of conducting lithium ions. At least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer contains the solid electrolyte material according to the above embodiments.

According to yet another embodiment, there is provided a battery pack including the battery according to the above embodiments.

According to still another embodiment, there is provided a vehicle equipped with the battery pack according to the above embodiment.

FIG. 2 is a schematic diagram showing the crystal structure of a perovskite-type compound included in an example of a solid electrolyte material according to an embodiment; FIG. 4 is a schematic diagram showing a rhombohedral crystal structure of a NASICON-type compound included in another example of the solid electrolyte material according to the embodiment. 1 is a schematic cross-sectional view showing an example of an electrode body according to an embodiment; FIG. 1 is a schematic cross-sectional view showing an example of an electrode body having a bipolar electrode structure according to an embodiment; FIG. 1 is a schematic cross-sectional view of an example of a battery according to an embodiment; FIG. FIG. 4 is a schematic diagram showing one step of the method for manufacturing the electrode body according to the embodiment; FIG. 7 is a schematic diagram showing one step next to the steps of the manufacturing method shown in FIG. 6 ; FIG. 8 is a schematic diagram showing an electrode body manufactured by the manufacturing method shown in FIG. 7; The perspective view which shows roughly an example of the assembled battery which concerns on embodiment. 1 is an exploded perspective view schematically showing an example of a battery pack according to an embodiment; FIG. FIG. 11 is a block diagram showing an example of an electric circuit of the battery pack shown in FIG. 10; 1 is a partially transparent view schematically showing an example of a vehicle according to an embodiment; FIG. The figure which showed roughly an example of the control system regarding the electric system in the vehicle which concerns on embodiment.

_Li7La3Zr2O12 has excellent _{electrochemical} stability compared _{to conventional} solid electrolytes. On the other hand, this compound has the problem of low resistance to the reducing side over time. Since the solid electrolyte in which the atoms in the material are reduced exhibits electronic conductivity, the function of electrically insulating the positive electrode and the negative electrode is impaired. As a result, self-discharge of the battery may increase.

Embodiments will be described below with reference to the drawings. In addition, the same code|symbol shall be attached|subjected to the common structure through embodiment, and the overlapping description is abbreviate|omitted. In addition, each drawing is a schematic diagram for explaining the embodiments and facilitating their understanding, and the shapes, dimensions, ratios, etc. of the drawings differ from those of the actual device, but these are consistent with the following explanation and known techniques. Consideration can be taken into consideration and the design can be changed as appropriate.

[First Embodiment]
The solid electrolyte material according to the first embodiment contains an oxide containing an octahedral coordination structure. The octahedral coordination structure includes a metal element M and an oxygen atom (O) arranged around the metal element M. The metal element M contains Nb and Ta. The mass ratio α _Ta /α _Nb between the mass α _Nb of Nb and the mass α _Ta of Ta is within the range of 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ .

The solid electrolyte material according to the embodiment contains an oxide having an octahedral coordination structure of oxygen (O) centering on a metal element M as a basic skeleton. Based on the octahedral coordination structure, the oxide contains niobium (Nb) and a small amount of tantalum (Ta) as the metal element M, thereby improving the stability of the oxide skeleton. Therefore, it is possible to provide a solid electrolyte material that has a less expensive elemental composition, is chemically stable, has high resistance to reduction, and exhibits excellent ionic conductivity.

The stronger the bonding strength between the metal element M and the oxygen atom O, the higher the reduction resistance of the oxide. As a result, the stability of the skeleton of the solid electrolyte is increased. On the other hand, as the bonding strength between M and O is stronger, the flexibility of the skeleton in Li ion conduction tends to be impaired and the room temperature conductivity tends to be lower. Many solid electrolytes with high conductivity at room temperature have a narrow electrochemically stable potential window, and M atoms in the skeleton tend to be easily reduced when exposed to a reducing potential for a long time. It is known that if the metal element M contains tantalum (Ta), which is chemically stable and has strong bonding properties with oxygen, the flexibility of the skeleton is impaired. A solid electrolyte according to an embodiment contains an oxide containing niobium (Nb) and a small amount of tantalum (Ta) as a metal element Mα. By including the metal element Mα composed of Nb and Ta in the site of the metal element M in the crystal structure, both electrochemical stability and flexibility of the skeleton can be achieved.

In a compound having a crystal structure having gaps between crystal lattices that can serve as a conduction path for Li ions, the flexibility of the skeleton structure greatly affects the conduction of Li ions. The more flexible the material, the higher the Li ion conductivity tends to be. On the other hand, it is desirable to attract the electron cloud of oxide ions to the metal element M in order to increase the resistance to reduction. In the solid electrolyte according to the embodiment, the mass ratio α _Ta /α _Nb between the mass α _Nb of Nb contained in the oxide and the mass α _Ta of Ta contained in the oxide is 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ within the range of Each of these mass α _Nb and mass α _Ta can be expressed in units of ng (nanogram), for example. Although the unit of each mass is not particularly limited, each unit is aligned in the mass ratio α _Ta /α _Nb . When the metal element M includes a metal element Mα consisting of Nb and Ta, and the mass ratio α _Ta /α _Nb is within the range of 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ , the high A skeletal structure exhibiting flexibility can be obtained, and good resistance to reduction can be obtained.

With a moderate amount of Nb, flexible bonds between Nb and oxide ions predominate in the framework. On the other hand, by dispersing a small amount of Ta in the Nb sites (sites of the metal element M), local bonding between Ta and oxide ions is enhanced. Then, the electron cloud of oxide ions is attracted, so that reduction resistance can be enhanced. When the mass ratio α _Ta /α _Nb between Nb and Ta is 3×10 ⁻³ or less, the skeleton structure can have flexibility, so Li ions can easily move through the gaps in the lattice. When the mass ratio is 5×10 ⁻⁵ or more, a large amount of strong covalent bonds between Ta and oxide ions are contained, so that an oxide which is difficult to be reduced can be obtained. By including Nb and Ta in the mass ratio α _Ta /α _Nb within the above range, it is possible to obtain an oxide having a well-balanced crystal lattice flexibility and resistance to reduction.

Ta, which is contained in a trace amount as the metal element Mα, is contained as a central metal in the octahedral coordination structure. Ta is not simply contained as a compound mixed with an oxide containing an octahedral coordination structure containing Nb as a center or as a compound covering the oxide. In other words, the oxide contained in the solid electrolyte material according to the embodiment is different from a simple mixture of niobium oxide and tantalum oxide. The oxide can be said to be a composite compound in which the sites of the metal element M are equally occupied by Nb and Ta.

It is desirable that the valence of both Nb and Ta contained in the oxide as the metal element Mα is not less than 5. That is, in a desirable solid electrolyte material, the valence of Nb is 5.0 and the valence of Ta is 5.0. In addition, the solid electrolyte hardly becomes a peroxide state, and the valence of both Nb and Ta rarely exceeds 5. When the valence of Nb is 5.0 and the valence of Ta is 5.0 at the same time, the flexibility of the crystal lattice and the resistance to reduction are well balanced, and electron conduction in the solid electrolyte is interrupted to increase the amount of self-discharge. can provide a battery with less power consumption.

The metal element M, which is the central atom in the octahedral coordination structure, is at least one selected from the group consisting of Ti, Zr, Ga, Ge, Si, Fe, and P in addition to the metal element Mα (Nb and Ta). It is preferable that the metal element Mβ is further included. These elements Mβ can improve the stability of the oxide structure. Among the metal elements Mβ, Ti, Zr, Ga, and Ge can play a role as the central atom in the octahedral coordination structure as well as the metal element Mα. Here, at least one selected from the group consisting of Ti, Zr, Ga, and Ge is called a main element _Mβp .

Among the metal elements Mβ, Si, Fe, and P hardly function as central atoms. Here, at least one selected from the group consisting of Si, Fe, and P is called an auxiliary element _Mβs . These auxiliary elements _Mβs have a smaller valence than Mα forming the skeleton of the oxide, and can improve the flexibility and stability of the skeleton.

The element ratio E βs /E _Nb of the element abundance ratio E _βs of the auxiliary element Mβ _s to the element abundance ratio E _Nb of _Nb contained in the oxide is 1×10 ⁻⁴ or more and 5×10 ⁻³ or less. is preferred, and 5×10 ⁻⁴ or more and 1×10 ⁻³ or less is more preferred. When this ratio is 1×10 ⁻⁴ or more, the flexibility of the skeleton is further improved and the conductivity is increased. Also, the element ratio E _βs /E _Nb of the auxiliary element Mβ _s to Nb is preferably 5×10 ⁻³ or less. If it is larger than 5×10 ⁻³ , the local strain in the structure increases, so the stability of the crystal structure may rather deteriorate. A ratio of 5×10 ⁻⁴ or more and 1×10 ⁻³ or less is more preferable because it is easy to achieve both an improvement in ionic conductivity and a stable crystal structure.

The crystal structure of the oxide contained in the solid electrolyte material includes at least one selected from the group consisting of a perovskite structure and a NASICON structure.

For example, the solid electrolyte according to the embodiment may contain a compound having a perovskite structure represented by AMO ₃ as an oxide. The perovskite-type crystal structure belongs to the cubic system or to a slightly distorted quasi-crystal system from this system. The representative space group of this crystal structure is Pm3m.

An example perovskite structure is described with reference to FIG. FIG. 1 is a schematic diagram showing a crystal structure of a perovskite compound included in an example of a solid electrolyte material according to an embodiment.

The perovskite-type crystal structure has a three-dimensional framework formed by sharing vertices of MO _octahedra 5, and has a structure in which A-site ions 3 occupy 12 coordination sites between the three-dimensional frameworks. . The _MO6 octahedron 5 contains oxygen atoms 2 and M atoms (not shown). Oxygen atoms 2 at the vertices of the MO ₆ octahedron 5 are arranged around the metal element M at the center of the octahedral site 6 .

If the A sites are not completely filled with elements and vacancies (defect structures) are present, conduction pathways for Li ions 1 are formed here. Lithium ion conductivity is said to occur when Li ions 1 migrate to adjacent vacant A sites through the oxide ion quadrilateral bottlenecks present in the plane of the cubic lattice. When Li ions 1 move in the crystal lattice by this conduction mechanism, the bond strength between the oxide ions and the cations (mainly M-site cations) forming the skeleton has a great effect on the lithium ion conductivity. Therefore, for the same reason as described above, reducing resistance can be improved while maintaining the flexibility of the skeleton by setting the mass ratio α _Ta /α _Nb within the above range. In addition, since Nb and Ta, which are metal elements Mα, coexist at the M atom site, local strain in the crystal lattice is suppressed.

In addition to Li and vacancies, the A site preferably further contains at least one selected from the group consisting of La, Sr, Mg, Na, K, and Ca. This can increase the stability of the perovskite structure.

Compounds with a perovskite structure may include, for example, compounds represented by the general formula A(Mα _1-w Mβ _w )O ₃ . Here, the subscript w in the general formula is within the range of 0≦w<1. The symbol A in the formula represents an element or vacancy occupying the A site. The A site contains at least Li and vacancies. The A site may further contain at least one selected from the group consisting of La, Sr, Mg, Na, K, and Ca. Mα and Mβ in the formula represent the metal element Mα (that is, Nb and Ta) and the metal element Mβ (main element Mβ _p and/or auxiliary element Mβ _s ) described above, respectively.

Alternatively, the solid electrolyte material according to the embodiment may contain a compound having a NASICON structure as an oxide. A compound having a NASICON-type crystal structure has, for example, a structure with phosphoric acid (PO ₄ ) as a skeleton structure. As such a structure, a crystal structure belonging to a rhombohedral structure can be mentioned, and a representative space group is R-3c. In the rhysohedral structure, PO ₄ tetrahedrons and MO ₆ octahedra share all vertices with each other, forming a skeleton structure represented by the chemical formula [M ₂ (PO ₄ ) ₃ ] ^n- .

An example of the NASICON structure will be described with reference to FIG. FIG. 2 is a schematic diagram showing a rhombohedral crystal structure of a NASICON-type compound included in another example of the solid electrolyte material according to the embodiment. In the skeleton structure of the rhysohedral crystal system shown in FIG. 2, there are four octahedra around one tetrahedron and six tetrahedra around one octahedron. General NASICON-type compounds take a rhombohedral crystal system as shown in Fig. 2 only at high temperatures, and at low temperatures, the skeletal structure is distorted and the symmetry is reduced, resulting in a monoclinic system (space group C2/c). is known to be

As shown in FIG. 2, Li ions 1 are present in the interstices of the lattice in a manner that compensates for the negative charge of the framework structure. There are four types of sites that can be occupied by Li ions. The first is a highly distorted octahedral site 6, which exists one per unit chemical formula. There are also sites surrounded by eight oxygen atoms 2, three per unit chemical formula. Furthermore, there are sites occupied by atoms 4 of the metal element M, and there are two sites per unit chemical formula. Finally, there is a tetrahedral site 7 flanked by two PO ₆ , one per unit formula. Since the sites occupied by Li ions are thus widely distributed in the crystal lattice, it is easy to form conduction paths for Li ions in the crystal structure.

In such a structure as well, when the flexibility of the skeleton structure is increased, the Li ion conductivity is improved. Therefore, when the metal element Mα (Nb and Ta) is contained at the site of the atom 4 of the metal element M, and the mass ratio _αTa / _αNb satisfies the above range, reduction resistance can be obtained while maintaining the flexibility of the skeleton. can improve sexuality.

Distortion of the NASICON structure can be suppressed by arranging the metal element Mβ at the site of the metal element M in addition to the metal element Mα.

Furthermore, it is preferable to replace the metal element M with at least one selected from the group consisting of Ca, Sr, and Ba. These Ca, Sr, and Ba are here called D elements for convenience. By substituting these D elements having a large ionic radius in the framework structure containing Nb and Ta, it is possible to obtain an elemental composition suitable for constructing a path for easy conduction of lithium ions. Substitution with Ba and Sr, which have larger ionic radii than Ca, is more preferable. With such a configuration, distortion of the skeleton structure at low temperatures is less likely to occur, and the rhombohedral structure, which is called the high-temperature phase of the NASICON structure, can be stabilized at temperatures below room temperature. In addition, Li ions can easily move even in a temperature range lower than room temperature. Substitution of the D element into the lattice can enlarge the framework size, making the Li ion less susceptible to electronic correlation from oxide ions. As a result, the Li ions can easily move even in a low-temperature temperature range where the thermal vibration that is important for Li ion movement is weakened.

On the other hand, even in a compound having a monoclinic structure, which is said to have a large amount of distortion in the crystal structure, the skeleton size can be increased by substituting the D element into the lattice. Therefore, even in a compound with a monoclinic structure, by introducing these D elements, Li ions can easily move in a temperature range lower than room temperature as in the high temperature phase.

The distribution of Ta may be uniform over the entire site of the metal element M in the crystal structure, or the distribution of Ta may be uneven. Rather than randomly arranging Ta in the crystal structure, it is desirable that the arrangement of Ta is unevenly distributed to a certain degree. The uneven distribution here means that the average bond distance between Ta and Ta in the crystal lattice is smaller than the average bond distance between Nb and Ta.

Compounds having the NASICON structure can include, for example, compounds represented by the general formula Li _x Mα _y (Mβ _1-z D _z )(PO ₄ ) ₃ . Here, the subscript x in the general formula is within the range of 0<x≤2, the subscript y is within the range of 0<y≤1, and the subscript z is within the range of 0≤z≤1. Mα and Mβ in the formula represent the metal element Mα and metal element Mβ described above, respectively. D in the formula is at least one selected from the group consisting of Ca, Sr, and Ba. The NASICON structure of this compound includes at least one selected from the group consisting of a rhombohedral structure and a monoclinic structure.

<Method for producing oxide>
An example of a method for producing the oxide contained in the solid electrolyte material according to the first embodiment is a solid phase reaction method. As raw materials for the solid-phase reaction, oxides of constituent elements or various salt compounds such as carbonates and nitrates that generate constituent elements by heating can be used. Various raw materials are mixed in a predetermined ratio so as to correspond to the target composition. By firing this mixture, an oxide containing an octahedral coordination structure containing the metal element M and oxygen atoms can be obtained.

For example, various raw materials are mixed in a predetermined ratio so as to correspond to the target composition represented by the above general formula A(Mα _1-w Mβ _w )O ₃ . By firing this mixture, a compound having a perovskite structure can be obtained. Alternatively, for example, various raw materials are mixed in a predetermined ratio so as to correspond to the target composition represented by the above general formula Li _x Mα _y (Mβ _1-z D _z )(PO ₄ ) ₃ . By firing this mixture, a compound having a NASICON structure can be obtained.

Phosphate salts such as ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ) are preferred as the phosphate source used to synthesize the NASICON structure oxide. Phosphate may be used alone or in combination of two or more as the phosphoric acid source. As a raw material of the metal element M, it is preferable to use an oxide. The oxides as the raw material of the metal element M may be used singly or in combination of two or more. Metal salts such as chlorides, carbonates and nitrates are preferably used as raw materials for the element that can be included in the A site of the perovskite structure and the D element that can be included in the NASICON structure. You may use these raw materials individually or in combination of 2 or more types.

First, as described above, these raw materials are mixed in a ratio corresponding to the target composition to obtain a mixture. This mixture is first subjected to a low temperature heat treatment.

Here, when obtaining a compound having a NASICON structure, it is desirable to perform a preheat treatment. Since the raw material of the compound with the NASICON structure contains a phosphate, if the compound is synthesized by a generally known solid-phase reaction method, the melting reaction is violent and light elements transpire. Therefore, when a general synthesis method is adopted, generation of an impurity phase and composition deviation occur. By adding a low-temperature heat treatment in which the mixture is heated at a temperature of 150 ° C. or higher and 350 ° C. or lower, for example, for 12 hours, then taken out of the furnace and rapidly cooled, the phosphate is first decomposed and combined with other raw materials. A melting reaction can be suppressed. A temperature higher than the melting point of the phosphate used by 100° C. or higher (exceeding about 350° C.) is not preferable because a melting reaction between the phosphate and other raw materials occurs, resulting in evaporation of light elements. In addition, at a temperature (less than about 150° C.) lower than the melting point of the phosphate initially used, the phosphate is not sufficiently decomposed and the phosphate decomposing effect is difficult to obtain.

By re-pulverizing the mixture subjected to the low-temperature heat treatment and calcining at 600° C. or higher and 800° C. or lower, a uniform mixed state can be obtained by thermal diffusion. If the calcination temperature is less than 600°C, it is difficult to obtain a sufficient mixed state. On the other hand, if the calcining temperature exceeds 800° C., sintering progresses and it is difficult to obtain a uniform mixed state. The calcination time is preferably about 5 hours to 20 hours.

When phosphate is not used as a raw material as in the synthesis of a perovskite structure compound, the above preheat treatment (low-temperature heat treatment) can be omitted. After obtaining the mixture of raw materials, calcination can be performed as it is.

The raw material mixture thus temporarily sintered is pulverized and mixed, and sintered at 1000° C. or higher and 1400° C. or lower in the air or under the flow of oxygen gas or nitrogen gas. At this time, in order to obtain a single phase with the desired crystal structure, it is preferable to repeat firing and re-pulverization to perform firing in a plurality of steps. The pulverization method is not particularly limited.

It is desirable to perform an annealing treatment in an oxygen atmosphere after performing the synthesis firing described above. Specifically, annealing is performed as follows. For example, a sample is placed in a tubular furnace and the inside is filled with pure oxygen gas. After that, annealing treatment is performed at 600° C. for 12 hours while performing pure oxygen flow at 0.5 L/min. By performing the annealing treatment, an oxide in which the valence of Nb is 5.0 and the valence of Ta is 5.0 can be obtained.

Moreover, it is also possible to construct an all-solid-state battery using a positive electrode material and a negative electrode material containing the solid electrolyte material according to the embodiment during firing. In this case, the material powder is stacked so that a layer of the solid electrolyte material is laminated between the positive electrode layer and the negative electrode layer in the obtained all-solid-state battery, and the powder is solidified by pressure molding or the like. By firing, an all-solid-state battery with a small grain boundary at the interface can be obtained. If the sintering temperature is lower than 1000° C., the reactivity is poor, the sintering takes a long time, and it is difficult to obtain the desired phase. If the firing temperature is higher than 1400° C., the transpiration of alkali metals including lithium and alkaline earth metals increases, and the composition tends to deviate from the desired composition. The total firing time depends on the firing temperature, but is generally 1 to 5 hours. Among them, it is preferable to perform the sintering at a temperature of 1300° C. for about 2 to 3 hours. Air is preferable as the firing atmosphere from the viewpoint of cost and convenience. Moreover, in order to prevent composition deviation due to lithium transpiration during firing, it is preferable to estimate the transpiration amount in advance and mix a large amount of the lithium raw material accordingly.

<Measurement of solid electrolyte material>
A method for measuring the solid electrolyte material will be described below. Specifically, powder X-ray diffraction measurement, electron probe microanalysis analysis, transmission electron microscope-energy dispersive X-ray spectroscopy, and inductively coupled plasma emission spectroscopy will be described.

(Powder X-ray diffraction measurement)
The crystal structure of the oxide contained in the solid electrolyte material can be confirmed by powder X-ray diffraction measurement.

When the solid electrolyte material to be measured is included in the battery, the measurement sample is taken out of the battery by, for example, the method described below.

For example, in an all-solid-state battery including an electrode body having a structure in which a positive electrode layer, a negative electrode layer, and an electrolyte layer are laminated to be described later, the solid electrolyte material may be included in the electrolyte layer. First, let the battery fully discharge. For example, the battery can be placed in a discharged state by discharging the battery to the rated final voltage at 0.1 C current in a 25° C. environment. Remove the electrode assembly from the battery. The electrolyte layer can be taken out by grinding off the positive electrode layer and the negative electrode layer in the electrode body taken out from the battery. The electrolyte layer thus taken out is pulverized to an average particle size of about 10 μm. The average particle size can be determined by a laser diffraction method. The pulverized sample is packed in a flat plate holder portion with a depth of 0.2 mm formed on a glass sample plate. At this time, care should be taken so that the sample is sufficiently filled in the holder portion. Also, make sure that there are no cracks or voids due to insufficient filling of the sample. Then, using another glass plate from the outside, it is sufficiently pressed and smoothed. Be careful not to cause unevenness from the reference surface of the holder due to excessive or insufficient filling. Next, the glass plate filled with the sample is placed in a powder X-ray diffractometer, and an X-ray diffraction (XRD) pattern is obtained using Cu—Kα rays.

In addition, when the orientation of the sample is high, there is a possibility that the position of the peak may shift or the peak intensity ratio may change depending on how the sample is filled. In the case of such a highly oriented sample, the sample is enclosed in a capillary, placed on a rotating sample stage, and measured while being rotated. By such a method, the XRD pattern of the sample can be obtained while reducing the influence of the orientation. If the intensity ratio measured by this method differs from the intensity ratio measured using the above-mentioned flat plate holder, the influence of the orientation may be considered, so the measurement result of the rotating sample stage is adopted.

Moreover, by measuring by such a method, it is possible to eliminate the difference in the measurement result depending on the operator and improve the reproducibility. The lattice constant can be refined from the obtained diffraction pattern by Rietveld analysis or the like.

As will be described later, the solid electrolyte material can be included in the battery as a composite electrolyte in which the solid electrolyte material and polymer electrolyte are mixed. In the case of a battery containing such a composite electrolyte, the surface coated with the solid electrolyte can be exposed by washing the surface of the electrode body removed from the battery with a solvent such as ethyl methyl carbonate. can. Measurement is performed by setting the surface coated with the inorganic solid particles to the same height as the surface of the glass holder for XRD. At this time, the peaks attributed to the active material (positive electrode active material or negative electrode active material) contained in the sample are grasped in advance, and the peaks of these active materials are separated from the spectrum after measurement for various analyses. I do. Dual phase analysis using the Rietveld method is preferred for peak separation.

(Electron probe microanalysis)
The valences of Nb and Ta in the oxide can be determined by analysis using an Electron Probe Micro Analyzer (EPMA). As a measuring device, JXA 8900 manufactured by JEOL can be used. An electron beam is irradiated under the conditions of a beam energy of 15 kV, a beam current of 100 nA, and a beam diameter of 10 μm, and Lα rays of Nb and Ta are measured with an analyzing crystal. Based on the peak shift, the valences of the measured elements are obtained. In this way, an average value can be obtained for each of the valences of Nb and Ta in the crystal structure of the oxide. It is not necessary to measure the entire crystal structure, and the average Nb valence and the average Ta valence can be obtained by partially confirming the crystal structure.

(Transmission electron microscope - energy dispersive X-ray spectroscopy)
The distribution of Ta in the crystal structure of the solid electrolyte material can be confirmed by measurement by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX). A sample of interest containing the solid electrolyte material is subjected to TEM-EDX measurements to identify the crystal structure of each particle in the sample by selected area diffraction. For example, when an electrode containing a solid electrolyte material is used as a measurement sample, the electrode active material may be contained in addition to the solid electrolyte material. By specifying the crystal structure, it is possible to distinguish between the solid electrolyte and the electrode active material. The distribution of Ta can be obtained by obtaining the mapping of Ta with EDX.

Also, the distribution of other elements in the crystal structure, such as Nb and the metal element Mβ, can be obtained by obtaining the mapping.

(Inductively Coupled Plasma Emission Spectroscopy)
When it is confirmed from the result of each mapping by TEM-EDX that the target element is contained in the crystal structure, quantitative analysis can be performed by high frequency inductively coupled plasma (ICP) emission spectrometry. By quantitative analysis, the mass ratio α _Ta /α _Nb and the element ratio E _βs /E _Nb of the auxiliary element Mβ _s to Nb can be calculated.

At this time, the abundance ratio (molar ratio) of each element depends on the sensitivity of the analyzer used. Therefore, for example, when the composition of an oxide contained in an example of the solid electrolyte material according to the first embodiment is analyzed using ICP emission spectroscopy, the error of the measuring device is calculated from the molar ratio described above. values may deviate. However, even if the measurement results deviate within the error range of the analyzer as described above, the exemplary solid electrolyte material according to the first embodiment can sufficiently exhibit the effects described above.

In order to measure the composition of the solid electrolyte material incorporated in the battery by ICP emission spectroscopy, for example, the electrolyte layer and the active material layer are taken out in the same procedure as described for the powder X-ray diffraction measurement. , can be used for measurement. The removed material layer is heated in the air for a short period of time (for example, at 500° C. for about 1 hour) to burn off unnecessary components such as the binder component and carbon. By dissolving this residue with an acid, a liquid sample containing the solid electrolyte material can be prepared. At this time, hydrochloric acid, nitric acid, sulfuric acid, hydrogen fluoride, etc. can be used as the acid. By subjecting this liquid sample to ICP analysis, the composition in the solid electrolyte material can be known.

According to the first embodiment described above, a solid electrolyte material containing an oxide containing an octahedral coordination structure is provided. The octahedral coordination structure has a structure including a metal element M and oxygen atoms arranged around the metal element M. The metal element M includes a metal element Mα containing Nb and Ta. The mass ratio α _Ta /α _Nb between the mass α _Nb of Nb and the mass α _Ta of Ta in the metal element Mα is within the range of 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ . This solid electrolyte material has high resistance to reduction. In addition, solid electrolyte materials can be manufactured at low cost while having chemical stability of constituent elements.

[Second embodiment]
According to a second embodiment, an electrode is provided. An electrode according to the second embodiment includes the solid electrolyte material according to the first embodiment.

The electrode according to the embodiment is, for example, a battery electrode. The term "battery" as used herein includes, for example, a storage battery capable of storing electric power, and a specific example thereof is a secondary battery such as a lithium ion battery.

The electrodes may further include an active material. The active material may be a battery active material. For example, an active material capable of intercalating/deintercalating lithium ions can be used.

An electrode according to the second embodiment can include a current collector and an active material-containing layer. The active material-containing layer may be formed on one side or both sides of the current collector. The active material-containing layer can contain an active material and optionally a conductive agent and a binder.

The electrode can be a positive electrode. The positive electrode may contain a positive electrode active material as a battery active material. The positive electrode can include a positive electrode active material containing layer containing a positive electrode active material as an active material containing layer. The details of the positive electrode active material-containing layer are the same as the details of the positive electrode layer to be described later, and therefore the description thereof is omitted.

The electrode can be the negative electrode. The negative electrode may contain a negative electrode active material as a battery active material. The negative electrode can include a negative electrode active material containing layer containing a negative electrode active material as an active material containing layer. The details of the negative electrode active material-containing layer are the same as the details of the negative electrode layer to be described later, and therefore the description thereof is omitted.

The electrodes may have a bipolar electrode structure as described below. Since the description overlaps with the description to be described later, the description is omitted.

Details of the current collector will be described later.

According to the second embodiment described above, an electrode containing the solid electrolyte material according to the first embodiment is provided. Since the solid electrolyte material of this electrode has high ionic conductivity and excellent resistance to reduction, it is possible to realize a battery with high input/output performance and excellent storage performance.

[Third Embodiment]
According to a third embodiment, a battery is provided that includes a positive electrode layer, a negative electrode layer, and a Li conducting layer. The positive electrode layer is capable of intercalation/deintercalation of lithium ions. The negative electrode layer is capable of intercalation/deintercalation of lithium ions. The Li conductive layer is capable of conducting lithium ions. At least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer contains the solid electrolyte material according to the first embodiment.

A battery according to an embodiment may be, for example, a storage battery capable of storing electric power, and a specific example thereof is a secondary battery such as a lithium ion battery.

The positive electrode layer may include a positive electrode active material and be disposed on the current collector to form a positive electrode. The negative electrode layer may include a negative electrode active material and be disposed on the current collector to constitute the negative electrode. Alternatively, the positive electrode layer can be disposed on one side of the current collector and the negative electrode layer can be disposed on the opposite side of the current collector to form an electrode of bipolar type construction. Each of the positive electrode layer and the negative electrode layer can contain an electrolyte. Also, the electrolyte that can be included in the positive electrode layer and the negative electrode layer can be the solid electrolyte material according to the first embodiment. The positive electrode active material and the negative electrode active material will be described later.

The Li-conducting layer is capable of conducting lithium ions and can be, for example, a separator disposed between the positive and negative electrode layers. Alternatively, the Li conducting layer can be the electrolyte layer. A Li-conducting layer as an electrolyte layer contains an electrolyte, which may contain the solid electrolyte material according to the first embodiment.

A battery according to an embodiment includes an exterior member. A positive electrode, a negative electrode, and an electrolyte are housed in an exterior member. Moreover, when a non-aqueous electrolyte is used together depending on the application, the non-aqueous electrolyte is also accommodated in the exterior member. Furthermore, a bipolar type structure can be used as the electrode structure.

FIG. 3 shows an example electrode assembly that can be included in the battery of the embodiment. The electrode assembly 10A shown in FIG. 3 includes a positive electrode layer 11, an electrolyte layer 12, a negative electrode layer 13, and a current collector 14. As shown, the electrode body 10A has a structure in which these members are laminated such that the electrolyte layer 12 is interposed between the positive electrode layer 11 and the negative electrode layer 13 and the current collectors 14 are arranged at both ends. In the example of FIG. 3, the electrode body 10A is a single-layer electrode body in which one set of the above structure is laminated.

Although FIG. 3 shows an example in which the electrolyte layer 12 is included as the Li conductive layer interposed between the positive electrode layer 11 and the negative electrode layer 13, in the battery of the embodiment, the Li conductive layer is not the electrolyte layer 12. good too. For example, when the positive electrode layer 11 and/or the negative electrode layer 13 contain an electrolyte as described later, a separator or the like holding the electrolyte as a Li conductive layer is disposed between the positive electrode layer 11 and the negative electrode layer 13. good too.

As an example of another aspect of the battery of the embodiment, an electrode body 10B having a bipolar electrode structure can be configured as shown in FIG. 4 and included in the battery. That is, one set of structures in which the current collector 14, the negative electrode layer 13, the electrolyte layer 12, and the positive electrode layer 11 are laminated in this order, two or more sets are laminated, and The current collector 14 may be laminated. In other words, the electrode body 10B includes a plurality of laminates in which the positive electrode layer 11, the Li conductive layer, and the negative electrode layer 13 are laminated in this order, and the current collector 14, and the positive electrode layer 11 of one laminate is It can have a bipolar electrode structure with a current collector 14 disposed between it and the negative electrode layer 13 of another laminate. The number of sets for stacking this structure can be appropriately selected according to the design of the shape and size of the battery. In the illustrated example, five sets are stacked. The electrode body 10B according to the present embodiment can be made thin by adhering the positive electrode layer 11, the electrolyte layer 12, and the negative electrode layer 13, respectively. A battery having a large capacity and excellent electrochemical stability can be obtained. As with the electrode body 10A in FIG. 3, in the electrode body 10B having a bipolar structure, when the positive electrode layer 11 and/or the negative electrode layer 13 contain an electrolyte, the separator holding the electrolyte as the Li conductive layer etc. may be arranged between the positive electrode layer 11 and the negative electrode layer 13 instead of the electrolyte layer 12 .

FIG. 5 shows a schematic cross-sectional view of an example battery according to the embodiment.

As shown in FIG. 5, the battery 100 includes a bipolar electrode assembly 10C housed in an exterior member 101. As shown in FIG. The illustrated electrode body 10C has a structure in which a current collector 14, a negative electrode layer 13, an electrolyte layer 12, and a positive electrode layer 11 are laminated in this order from the bottom, similar to the electrode body 10B shown in FIG. It has a structure in which more than one set is laminated, and a current collector 14 is laminated on one side of the uppermost positive electrode layer 11 . A positive electrode terminal 9 is electrically connected to the current collector 14 (upper end in the drawing) adjacent to the positive electrode layer 11 at the end. A negative electrode terminal 8 is electrically connected to the current collector 14 (lower end in the drawing) adjacent to the negative electrode layer 13 at the end. These positive electrode terminal 9 and negative electrode terminal 8 extend outside the exterior member 101 .

In the battery 100 shown in FIG. 5, similarly to the electrode assembly 10B shown in FIG. However, the number of sets of the laminated structure included in the electrode body 10C may be, for example, one like the electrode body 10A in FIG. 3, or may be two or more.

The electrolyte, positive electrode layer, negative electrode layer, and exterior member will be described in detail below.

1) Electrolyte In the battery according to the embodiment, the positive electrode layer, the negative electrode layer, and the Li conductive layer may contain an electrolyte. The electrolyte that can be included in any layer can be the solid electrolyte material according to the first embodiment. In the battery according to the embodiment, at least one of these layers contains the solid electrolyte material according to the first embodiment. Batteries using a solid electrolyte material do not have to worry about organic electrolyte leakage or gas generation, and can provide a safe battery.

In the layer containing the solid electrolyte material described in the first embodiment, this lithium ion conductive solid electrolyte material may be used alone, or other types of solid electrolytes (for example, other NASICON type solid electrolytes) may be used. electrolyte, other perovskite-type solid electrolytes, garnet-type solid electrolytes, LISOCON-based solid electrolytes, sulfide-based solid electrolytes). A more preferred embodiment of the battery contains, as an electrolyte, a composite electrolyte containing the solid electrolyte material according to the first embodiment and an organic electrolyte. The solid electrolyte material forms inorganic solid particles. It is preferable that the inorganic solid particles and the organic electrolyte form a composite electrolyte.

The organic electrolyte in the composite electrolyte is selected from the group consisting of Li (lithium) ions exhibiting ionic conductivity and propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC). contains at least one It is not preferable to use sulfide solid electrolyte particles with high Li ion conductivity as the inorganic solid particles forming the composite electrolyte together with the organic electrolyte because the sulfur component dissolves.

The mass ratio of the organic electrolyte in the composite electrolyte is 0.1% or more and 20% or less. In other words, the content of the organic electrolyte is 0.1 parts by mass to 20 parts by mass when the total amount of the composite electrolyte is 100 parts by mass. The mass ratio of the organic electrolyte in the composite electrolyte is preferably 1% or more and 10% or less, particularly preferably about 4%.

The composite electrolyte may further contain a binder. As the binder, it is more preferable to use a polymer that gels with carbonates such as polyacrylonitrile (PAN), polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), or polymethyl methacrylate. In the case of PVdF, for example, the content of the binder is preferably less than 20% by mass with respect to the total mass of the composite electrolyte.

The composite electrolyte is preferably a solid polymer electrolyte or gel polymer electrolyte. Whether the composite electrolyte becomes solid or gel can be appropriately adjusted by selecting the composition of the organic electrolyte and the binder. If the composite electrolyte is a solid polymer electrolyte, generally the battery device can be made compact. If the composite electrolyte is a gel-like polymer electrolyte, operations such as fabrication of the battery device and modification of the shape are easy.

According to the composite electrolyte according to the embodiment, ion conductivity can be enhanced by combining the solid electrolyte material according to the first embodiment and the organic electrolyte. This is because the concentration of mobile Li ions increases at the interface between the Li ion conductive inorganic solid particles and the organic electrolyte, facilitating the movement of Li ions. If a Li-containing oxide solid electrolyte with high Li ion conductivity is used as the organic electrolyte, the movement of Li ions becomes easier.

In addition, by using the above-described organic electrolyte and inorganic solid particles (particles of the solid electrolyte material according to the first embodiment), the inorganic solid particles become chemically stable with respect to the organic electrolyte, dissolving the inorganic solid particles, etc. does not cause such problems. In addition, the use of the Li ion conductive inorganic solid particles makes it difficult for the reduction reaction accompanying the movement of Li to occur even at high temperatures, thereby increasing the stability and life of the composite electrolyte.

The surfaces of the positive electrode layer 11 and the negative electrode layer 13 may be uneven rather than flat, as exemplified in FIGS. 6-8. In the battery according to the embodiment, for example, as shown in FIG. The interface with the layer 13 can be formed along the surface irregularities of the positive electrode layer 11 and the negative electrode layer 13 . An example of this is shown in FIG. The inorganic solid particles 121 may include particles of the above-described solid electrolyte (the solid electrolyte material according to the first embodiment and other solid electrolytes). As shown in FIGS. 6 to 8, the surfaces of the positive electrode layer 11 and the negative electrode layer 13 have irregularities due to the material (particles of the active material described later, etc.) forming each electrode. In particular, the surface of the negative electrode layer 13 has large irregularities when secondary particles having an average secondary particle diameter of more than 5 μm are used as the negative electrode active material particles, as will be described later. The electrolyte layer 12 adheres to the positive electrode layer 11 and the negative electrode layer 13 along the unevenness. Specifically, since the organic electrolyte 122 is gel-like in the manufacturing process described later or has fluidity before curing, it penetrates into recesses formed by particles on the surfaces of the positive electrode layer 11 and the negative electrode layer 13 . I'm in.

With such a structure, the surface of the electrolyte layer 12 is formed along the irregularities of the surfaces of the positive electrode layer 11 and the negative electrode layer 13 so that the surfaces of the electrolyte layer 12, the positive electrode layer 11 and the negative electrode are in close contact with each other. There is almost no gap between it and the layer 13 . In particular, as shown in FIG. 8, when the inorganic solid particles 121A, which are part of the inorganic solid particles 121, enter deep into the concave portions of the negative electrode layer 13, the inorganic solid particles are formed on the surface of the negative electrode layer 13 including the concave portions. Good conductivity is provided through the particles 121A. Further, in the electrolyte layer 12, for example, when inorganic solid particles 121B, which are hard particles, are included as solid electrolyte particles, the hard inorganic solid particles 121B impart structural strength to the electrolyte layer 12, It also has the effect of ensuring a certain thickness for the electrolyte layer 12 . This can prevent the positive electrode layer 11 and the negative electrode layer 13 from being in direct contact with each other and short-circuiting.

Alternatively, the composite electrolyte may be included in the positive electrode layer 11 in a state of covering at least part of the particles of the positive electrode active material, for example. That is, when the positive electrode layer 11 contains an electrolyte, the composite electrolyte described above may be in a state of covering individual positive electrode active material particles. Similarly, the composite electrolyte can be included in the negative electrode layer 13 in a state of covering at least a portion of the particles of the negative electrode active material, for example. That is, when the negative electrode layer 13 contains an electrolyte, the composite electrolyte described above may be in a state of covering individual negative electrode active material particles. The positive electrode layer 11 and the negative electrode layer 13 in such a state can be regarded as polymeric material layers.

In the battery according to the embodiment, when the electrolyte layer 12 is used, for example, the organic electrolyte constituting the composite electrolyte described above is applied to the positive electrode layer 11 or the negative electrode layer 13, or the positive electrode layer 11 and the negative electrode layer are arranged parallel to each other. Electrolyte layer 12 can be fabricated by means such as injection between 13 .

As a more specific example, the electrolyte layer 12 can be manufactured by, for example, the following manufacturing method. In this specific example, a method for manufacturing the electrolyte layer 12 on the positive electrode layer 11 will be described, but the method for manufacturing the electrolyte layer 12 according to the embodiment is not limited to this. First, inorganic solid particles 121 are dispersed in a solution containing a binder to prepare a binder dispersion of solid electrolyte particles. Here, the binder can be of any of the types described above. The inorganic solid particles 121 may be particles of the solid electrolyte material according to the first embodiment. Next, by applying this binder dispersion onto the positive electrode layer 11, inorganic solid particles 121 are provided on the positive electrode layer 11 as shown in FIG. After that, as shown in FIG. 7 , the positive electrode layer 11 is impregnated with an organic electrolyte 122 and heated and mixed to form a gel-like composite electrolyte 123 containing the organic electrolyte 122 and the inorganic solid particles 121 . can be done. Then, the positive electrode layer 11 and the negative electrode layer 13 are arranged opposite to each other and pressed to obtain an electrode body in which the composite electrolyte layer 12 is sandwiched between the positive electrode layer 11 and the negative electrode layer 13 as shown in FIG. can be done.

Here, by using the gel-like composite electrolyte 123 as the electrolyte layer 12 , when the negative electrode layer 13 is pressed against the composite electrolyte 123 on the positive electrode layer 11 , unevenness on the surface of the positive electrode layer 11 and the negative electrode layer 13 , particularly these The composite electrolyte 123 enters or permeates the unevenness of the active material that may exist on the surface of the electrode layer. Therefore, the positive electrode layer 11, the negative electrode layer 13, and the electrolyte layer 12 adhere to each other along the unevenness.

When a solid polymer is used as the organic electrolyte, the organic electrolyte having fluidity before solidification may be applied onto the positive electrode layer 11 . Moreover, when applying this on the positive electrode layer 11, if the fluidity of the organic electrolyte is sufficiently high, a spray method or the like may be used. By using the spray method, the composite electrolyte 123 can be uniformly provided on the positive electrode layer 11, and the thickness of the electrolyte layer 12 can be easily adjusted by adjusting the amount of the composite electrolyte 123 provided.

Further, when the electrolyte layer 12 is manufactured by injecting the organic electrolyte 122 between the positive electrode layer 11 and the negative electrode layer 13, specifically, for example, the positive electrode layer 11 and the negative electrode layer 11 having the inorganic solid particles 121 disposed therein After arranging the layer 13 with a certain distance (a value set as the thickness of the electrolyte layer 12), the organic electrolyte 122 may be injected and permeated.

In this embodiment, since the organic electrolyte 122 and the inorganic solid particles 121 are embedded in the fine concave portions of the positive electrode layer 11 and the negative electrode layer 13, respectively, the electrolyte layer 12 and the positive electrode layer 11 and the negative electrode layer 13 are closely attached without gaps. ing. Since the interfaces between the electrolyte layer 12 and the positive electrode layer 11 and the negative electrode layer 13 are well formed, ion conductivity via the electrolyte layer 12 is good. Since the positive electrode layer 11 and the negative electrode layer 13 are in close contact with the electrolyte layer 12, the thickness of the electrolyte layer 12 can be set within the small range described above.

2) Positive Electrode Layer The positive electrode layer 11 is carried on one side of the current collector 14 in the example of the single-layer electrode assembly 10A shown in FIG. The positive electrode layer 11 contains an active material (positive electrode active material), a conductive agent and a binder. Also, the positive electrode layer 11 may contain an electrolyte. This electrolyte can be the solid electrolyte described above (the solid electrolyte material according to the first embodiment and other solid electrolytes). Moreover, the aspect in which the positive electrode layer 11 contains a non-aqueous electrolyte as an electrolyte is also possible. The non-aqueous electrolyte referred to here includes, for example, a liquid non-aqueous electrolyte or a gel electrolyte using a non-aqueous electrolyte as a substrate.

As the current collector 14 carrying the positive electrode layer 11 on its surface, it is preferable to use a foil containing Al (aluminum). As such an Al-containing foil, it is preferable to use a pure Al (100% purity) aluminum foil or an Al alloy foil with an Al purity of 99% or more and less than 100%. The Al alloy is preferably an alloy containing, in addition to Al, one or more elements selected from the group consisting of Fe, Mg, Zn, Mn and Si. For example, Al--Fe alloys, Al--Mn based alloys and Al--Mg based alloys are capable of obtaining higher strength than Al. On the other hand, the content of transition metals such as Cu, Ni, and Cr in Al and Al alloys is preferably 100 ppm or less (including 0 ppm). For example, Al--Cu based alloys are not suitable for the current collector 14 because they have increased strength but deteriorated corrosion resistance.

A more preferable Al purity used for the current collector 14 supporting the positive electrode layer 11 is in the range of 99.0% or more and 99.99% or less. Within this range, deterioration of high-temperature cycle life due to dissolution of impurity elements can be reduced.

As the positive electrode active material, for example, oxides or sulfides can be used. The positive electrode may contain one type of compound alone as a positive electrode active material, or may contain two or more types of compounds in combination. Examples of oxides and sulfides include Li or compounds capable of intercalating and deintercalating Li ions.

Examples of such compounds include manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, and lithium manganese composite oxides (eg, Li _x Mn ₂ O ₄ or Li _x MnO ₂ ; 0<x≦1). , lithium-nickel composite oxides (for example, Li _x NiO ₂ ; 0<x≦1), lithium-cobalt composite oxides (for example, Li _x CoO ₂ ; 0<x≦1), lithium-nickel-cobalt composite oxides (for example, Li _x Ni _1-y Co _y O ₂ ; 0<x≦1, 0<y<1), lithium manganese cobalt composite oxide (for example, Li _{x Mny} Co _1-y O ₂ ; 0<x≦1, 0<y< 1) Lithium-manganese-nickel composite oxides having a spinel structure (e.g., Li _x Mn _2-y Ni _y O ₄ ; 0<x≦1, 0<y<2), lithium phosphorous oxides having an olivine structure (e.g., Li _xFePO4 ; 0<x≤1, _{LixFe1 - yMnyPO4} ; 0<x≤1, ₀ <y _< 1, _{LixCoPO4 ;} 0<x≤1), iron sulfate ( _Fe2 ( _SO4 ) ₃ ), vanadium oxide ( _e.g. , _V2O5 ), and lithium-nickel-cobalt-manganese composite _oxide ( _{LixNi1 - yzCoyMnzO2} ; 0< _x≤1 , 0<y <1, 0<z<1, y+z<1).

Among the above, examples of more preferable compounds as positive electrode active materials include lithium-manganese composite oxides having a spinel structure (e.g., Li _x Mn ₂ O ₄ ; 0<x≦1), lithium-nickel composite oxides (e.g., Li _{x NiO2} ; 0<x≤1), lithium cobalt composite _oxide (e.g. _LixCoO2 ; ₀ <x≤1), lithium nickel cobalt composite oxide (e.g. _{LixNi1 - yCoyO2} ; 0< x≤1, 0<y<1), lithium-manganese-nickel composite oxide having a spinel structure ( _e.g. , _{LixMn2 - yNiyO4} ; 0<x≤1, 0<y<2), lithium-manganese-cobalt Composite oxide (e.g. Li _x Mn _y Co _1-y O ₂ ; 0<x≦1, 0<y<1), lithium iron phosphate (e.g. Li _x FePO ₄ ; 0<x≦1), and lithium Nickel-cobalt-manganese composite oxides (Li _x Ni _1-yz Co _y Mn _z O ₂ ; 0<x≦1, 0<y<1, 0<z<1, y+z<1) are included. When these compounds are used as the positive electrode active material, the positive electrode potential can be increased.

A conductive agent is added to increase the electron conductivity in the positive electrode layer 11 and to suppress the contact resistance with the current collector 14 . Examples of conductive agents include vapor grown carbon fiber (VGCF), acetylene black, carbon black, and graphite.

Examples of binders for binding the active material and the conductive agent include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluororubber.

Regarding the compounding ratio of the positive electrode active material, the conductive agent and the binder, the positive electrode active material is 80% by mass or more and 95% by mass or less, the conductive agent is 3% by mass or more and 18% by mass or less, and the binder is 2% by mass or more. It is preferable to make it into the range below mass %. With respect to the conductive agent, when it is 3% by mass or more, the above effects can be exhibited, and when it is 18% by mass or less, decomposition of the non-aqueous electrolyte on the surface of the conductive agent during high-temperature storage is reduced. be able to. When the content of the binder is 2% by mass or more, sufficient electrode strength can be obtained, and when the content is 7% by mass or less, the insulating portion of the electrode can be reduced.

The positive electrode layer 11 is formed, for example, by suspending a positive electrode active material, a conductive agent, a binder, and optionally a solid electrolyte in an appropriate solvent, applying the suspension to the current collector 14, and then applying the suspension on the current collector 14. It can be carried on the current collector 14 by drying the coating film applied to and pressing it. The positive electrode press pressure is preferably in the range of 0.15 ton/mm or more and 0.3 ton/mm or less. Within this range, the adhesiveness (peel strength) between the positive electrode layer and the Al foil positive current collector is enhanced, and the elongation of the positive electrode current collector foil is preferably 20% or less.

3) Negative Electrode Layer The negative electrode layer 13 is supported on one side of the current collector 14 in the example of the single-layer electrode body 10A shown in FIG. The negative electrode layer 13 contains an active material (negative electrode active material), a conductive agent and a binder. Also, the negative electrode layer 13 may contain an electrolyte. This electrolyte can be the solid electrolyte described above (the solid electrolyte material according to the first embodiment and other solid electrolytes). Moreover, it is also possible to adopt a mode in which the negative electrode layer 13 contains a non-aqueous electrolyte as an electrolyte. The non-aqueous electrolyte referred to here includes, for example, a liquid non-aqueous electrolyte or a gel electrolyte using a non-aqueous electrolyte as a substrate.

As the current collector 14 carrying the negative electrode layer 13 on its surface, it is preferable to use a foil containing Al (aluminum). As such an Al-containing foil, an Al foil or an Al alloy foil is desirable. In particular, it is preferable to use a pure Al (100% purity) aluminum foil or an Al alloy foil with an Al purity of 98% or more and less than 100%. More preferably, the purity of the Al foil is 99.99% or higher. The thickness of the Al foil and Al alloy foil is, for example, 20 μm or less, more preferably 15 μm or less. The Al alloy is preferably an alloy containing, in addition to Al, one or more elements selected from the group consisting of Fe, Mg, Zn, Mn and Si. For example, Al--Fe alloys, Al--Mn based alloys and Al--Mg based alloys are capable of obtaining higher strength than Al. On the other hand, the content of transition metals such as Cu, Ni, and Cr in Al and Al alloys is preferably 100 ppm or less (including 0 ppm). For example, Al--Cu based alloys are not suitable for the current collector 14 because they have increased strength but deteriorated corrosion resistance.

The more preferable Al purity used for the current collector 14 on which the negative electrode layer 13 is supported is in the range of 98% or more and 99.95% or less. As will be described later, by using Ti-containing oxide particles having a secondary particle size of 2 μm or more as the negative electrode active material particles in the embodiment, the negative electrode pressing pressure can be reduced and the elongation of the Al foil can be reduced. Therefore, this purity range is suitable. As a result, there is an advantage that the electron conductivity of the Al foil current collector can be increased, and furthermore, crushing of the secondary particles of the titanium-containing oxide described later can be suppressed to obtain a low-resistance negative electrode layer.

Examples of negative electrode active materials into which Li is intercalated and deintercalated include carbon materials, graphite materials, Li alloy materials, metal oxides, and metal sulfides. Among these, those containing Ti element are preferable. Among them, it is particularly preferable to select a titanium-containing oxide whose potential at which Li ions are intercalated and deintercalated is in the range of 1 V or more and 3 V or less (vs. Li/Li ⁺ ) with respect to the oxidation-reduction potential of lithium.

Examples of titanium-containing oxides include lithium titanates with a ramsdellite structure (e.g. Li _2+y Ti ₃ O ₇ , where 0≦y≦3), lithium titanates with a spinel structure (e.g. Li _4+x Ti ₅ O ₁₂ , 0≦x≦3), monoclinic titanium dioxide (TiO ₂ ), anatase titanium dioxide, rutile titanium dioxide, hollandite titanium composite oxide, orthorhombic titanium composite oxide, and monoclinic niobium-titanium composite oxides.

Examples of the orthogonal titanium-containing composite oxide include a compound represented by Li _2+a M(I) _2-b Ti _6-c M(II) _d O _14+σ . Here, M(I) is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb and K. M(II) is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. Each subscript in the composition formula is 0≦a≦6, 0≦b<2, 0≦c<6, 0≦d<6, −0.5≦σ≦0.5. A specific example of the orthogonal titanium-containing composite oxide is Li _2+a Na ₂ Ti ₆ O ₁₄ (0≦a≦6).

Examples of the monoclinic niobium-titanium composite oxide include compounds represented by Li _x Ti _1-y M1 _y Nb _2-z M2 _z O _7+δ . Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. Each subscript in the composition formula is 0≦x≦5, 0≦y<1, 0≦z<2, −0.3≦δ≦0.3. A specific example of the monoclinic niobium-titanium composite oxide is Li _x Nb ₂ TiO ₇ (0≦x≦5).

Another example of the monoclinic niobium-titanium composite oxide is a compound represented by Li _x Ti _1-y M3 _y+z Nb _2-z O _7-δ . Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. Each subscript in the composition formula is 0≦x<5, 0≦y<1, 0≦z<2, −0.3≦δ≦0.3.

One of these may be used alone, or two or more may be used in combination. More preferably, spinel-structured lithium-titanium oxide represented by the general formula Li _4+x Ti ₅ O ₁₂ (where x is 0≦x≦3, more preferably −1≦x≦3) has an extremely small volume change. By using these titanium-containing oxides, Al foil can be used as the current collector for supporting the negative electrode layer in place of the conventional copper foil in the same manner as the positive electrode current collector. As a result, the weight and cost of the battery can be reduced. In addition, it is advantageous in terms of capacity per unit weight and size of a battery having a bipolar electrode structure, which will be described later.

The particles of the negative electrode active material preferably have an average primary particle size of 1 μm or less and a specific surface area of 3 m ² /g or more and 200 m ² /g or less as measured by the BET method using N ₂ adsorption. Thereby, when a non-aqueous electrolyte is used in the battery, the affinity between the negative electrode layer 13 and the non-aqueous electrolyte can be increased. Further, by setting the average primary particle size to 1 μm or less, the diffusion distance of Li ions inside the active material can be shortened. Also, the specific surface area can be increased. A method for measuring the specific surface area by the BET method will be described later. In addition, a more preferable average particle diameter is 0.1 μm or more and 0.8 μm or less.

The reason why the average particle size of the negative electrode active material is within the above range is that if the specific surface area of the negative electrode layer 13 is increased to 3 m ² /g or more and 50 m ² /g or less by using primary particles having an average particle size of more than 1 μm, the negative electrode This is because a decrease in the porosity of the layer 13 cannot be avoided. However, if the average particle diameter is small, aggregation of particles is likely to occur. Therefore, it is desirable to set the lower limit to 0.001 μm.

The negative electrode active material particles may contain secondary particles in addition to the primary particles described above. The average particle size (diameter) of the secondary particles of the negative electrode active material is preferably larger than 2 μm. More preferably, the secondary particle size of the negative electrode active material is larger than 5 μm. The most preferable secondary particle size is 7 μm or more and 20 μm or less. Within this range, a high-density negative electrode can be produced while the negative electrode pressing pressure is kept low, and elongation of the Al-containing foil as a current collector can be suppressed.

A negative electrode active material whose secondary particles have an average particle size of more than 2 μm can be obtained, for example, as follows. First, active material raw materials are reacted and synthesized to prepare an active material precursor having an average particle size of 1 μm or less, followed by firing treatment. The fired material is pulverized using a pulverizer such as a ball mill or jet mill, and then fired to aggregate the active material precursors into secondary particles with a large particle size. grow.

It is also preferable to coat the surfaces of the secondary particles with a carbon material in order to reduce the electrical resistance of the negative electrode layer. The secondary particles of the negative electrode active material coated with the carbon material can be produced, for example, by adding a precursor of the carbon material in the process of producing the secondary particles and firing at a temperature of 500° C. or higher in an inert atmosphere. can.

Further, secondary particles and primary particles of a titanium-containing oxide as a negative electrode active material may be mixed in the negative electrode layer 13 . From the viewpoint of achieving higher density, it is preferable that primary particles are present in the negative electrode layer in an amount of 5% by volume or more and 50% by volume or less.

Next, the reason for defining the specific surface area of the negative electrode layer 13 within the above range will be described. When the specific surface area is less than 3 m ² /g, aggregation of particles is conspicuous, so that, for example, when a non-aqueous electrolyte is used, the affinity between the negative electrode layer 13 and the non-aqueous electrolyte becomes low, and the interfacial resistance of the negative electrode layer 13 increases. As a result of the increase, output performance and charge/discharge cycle performance are degraded. On the other hand, when the specific surface area exceeds 50 m ² /g, the distribution of the non-aqueous electrolyte is biased toward the negative electrode layer 13, causing a shortage of the non-aqueous electrolyte in the positive electrode layer 11, so that the output performance cannot be improved. A more preferable range of the specific surface area is 5 m ² /g or more and 50 m ² /g or less. Here, the specific surface area of the negative electrode layer 13 means the surface area per 1 g of the negative electrode layer.

The negative electrode layer 13 can be, for example, a porous layer containing a negative electrode active material, a conductive agent, and a binder supported on a current collector. When the negative electrode layer 13 is porous, its porosity (excluding the current collector) is desirably in the range of 20% or more and 50% or less. As a result, for example, when a non-aqueous electrolyte is used in a battery, the negative electrode layer 13 can be obtained with excellent affinity between the negative electrode layer 13 and the non-aqueous electrolyte and with a high density. A more preferable range of porosity is 25% or more and 40% or less.

For example, a carbon material can be used as the conductive agent. Examples of carbon materials include vapor grown carbon fiber (VGCF), acetylene black, carbon black, coke, carbon fiber, graphite, Al powder, TiO, and the like. More preferably, the heat treatment temperature is 800° C. or higher and 2000° C. or lower, and coke, graphite, or TiO powder having an average particle diameter of 10 μm or less, or carbon fiber having an average fiber diameter of 1 μm or less is preferable. These carbon materials preferably have a specific surface area of 10 m ² /g or more as measured by the BET method using N ₂ adsorption.

Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber, core-shell binders, and the like.

The compounding ratio of the active material, the conductive agent, and the binder in the negative electrode layer 13 is 80% to 95% by mass of the negative electrode active material, 3% to 18% by mass of the conductive agent, and 2% to 7% by mass of the binder. % or less is preferable.

Although the dispersibility of the particles tends to increase as the amount of the binder added increases, the surface of the particles tends to be covered with the binder, and the specific surface area of the negative electrode layer 13 becomes smaller. On the other hand, if the amount of the binder added is small, the particles tend to aggregate, so it is desirable to control the aggregation of the particles by adjusting the stirring conditions (rotation speed of the ball mill, stirring time and stirring temperature). By doing so, the fine particles can be uniformly dispersed, and the negative electrode layer 13 in the embodiment can be obtained. Furthermore, even if the amount of the binder added and the stirring conditions are within appropriate ranges, if the amount of the conductive agent added is large, the surface of the negative electrode active material tends to be coated with the conductive agent, and the pores on the surface of the negative electrode tend to decrease. Therefore, the specific surface area of the negative electrode layer 13 tends to be small.

On the other hand, when the amount of the conductive agent added is small, the negative electrode active material is easily pulverized and the specific surface area of the negative electrode layer 13 is increased, or the dispersibility of the negative electrode active material particles is reduced and the specific surface area of the negative electrode layer 13 is decreased. tends to become smaller. Furthermore, not only the added amount of the conductive agent but also the average particle size and specific surface area of the conductive agent can affect the specific surface area of the negative electrode layer 13 . It is desirable that the conductive agent has an average particle size equal to or smaller than the average particle size of the negative electrode active material and a specific surface area larger than that of the negative electrode active material.

The negative electrode layer 13 is formed, for example, by suspending the above-described negative electrode active material, conductive agent, binder, and optionally a solid electrolyte in an appropriate solvent, applying the suspension to the current collector 14, and then applying the suspension to the current collector 14. The coating film applied on the current collector 14 can be dried and carried on the current collector 14 by applying a hot press. At this time, it is desirable to uniformly disperse the particles of the negative electrode active material while adding a small amount of the binder.

4) Exterior Member The electrode bodies 10A to 10C described above can be accommodated in a container as the exterior member 101 and used. A metal container or a laminate film container can be used as a container for housing the electrode bodies 10A to 10C.

As the metal container, a metal can made of Al, Al alloy, iron, stainless steel, or the like and having a rectangular or cylindrical shape can be used. The plate thickness of the container is preferably 0.5 mm or less, more preferably 0.3 mm or less.

Examples of laminate films include multilayer films in which Al foil is coated with a resin film. Polymers such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET) can be used as the resin. Also, the thickness of the laminate film is preferably 0.2 mm or less. The purity of the Al foil is preferably 99.5% or higher.

The metal can made of Al alloy is preferably made of an alloy containing at least one element selected from the group consisting of Mn, Mg, Zn and Si and having an Al purity of 99.8% or less. By using an Al alloy, the strength of the metal can is dramatically increased, and the thickness of the can can be reduced. As a result, it is possible to realize a battery that is thin, lightweight, high in output, and excellent in heat dissipation.

The above batteries may be electrically connected in series or parallel, combined with other types of batteries, and/or combined with a casing or the like to form a battery pack. A conventionally known configuration can be appropriately selected for the battery pack. Further, details of a specific example of the configuration of the battery pack will be described later.

<Method for measuring specific surface area>
The specific surface area is measured by adsorbing molecules having a known adsorption area on the surface of the powder particles at the temperature of liquid nitrogen and determining the specific surface area of the sample from the amount. The most commonly used is the BET method by low temperature and low humidity physical adsorption of an inert gas. This BET method is a method based on the BET theory, which is the most famous theory as a method for calculating the specific surface area, by extending the Langmuir theory, which is a monomolecular layer adsorption theory, to multi-molecular layer adsorption. The specific surface area thus determined is called the BET specific surface area.

According to the battery according to the third embodiment described above, a battery including a positive electrode layer, a negative electrode layer, and a Li conductive layer is provided. Lithium ions can be intercalated into and deintercalated from each of the positive electrode layer, the negative electrode layer, and the Li conductive layer. At least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer contains the solid electrolyte material according to the first embodiment. This battery has high input/output performance and excellent storage performance. In addition, the battery can be provided inexpensively.

[Fourth embodiment]
According to a fourth embodiment, an assembled battery is provided. An assembled battery according to the fourth embodiment includes a plurality of batteries according to the third embodiment.

In the assembled battery according to the fourth embodiment, each unit cell may be electrically connected in series or parallel and arranged, or may be arranged by combining series connection and parallel connection.

Next, an example of the assembled battery according to the fourth embodiment will be described with reference to the drawings.

FIG. 9 is a perspective view schematically showing an example of an assembled battery according to the fourth embodiment. The assembled battery 200 shown in FIG. 9 includes five single cells 100a to 100e, four bus bars 21, a positive electrode lead 22, and a negative electrode lead . Each of the five cells 100a-100e is a battery according to the third embodiment.

The bus bar 21 connects, for example, the negative terminal 8 of one unit cell 100a and the positive terminal 9 of the adjacent unit cell 100b. In this manner, five cells 100 are connected in series by four busbars 21 . That is, the assembled battery 200 in FIG. 9 is a five-series assembled battery. Although an example is not shown, in an assembled battery including a plurality of cells electrically connected in parallel, for example, a plurality of negative terminals are connected to each other by a bus bar and a plurality of positive terminals are connected to each other by a bus bar. Thus, a plurality of cells can be electrically connected.

The positive terminal 9 of at least one of the five cells 100a to 100e is electrically connected to a positive lead 22 for external connection. The negative terminal 8 of at least one of the five cells 100a to 100e is electrically connected to the negative lead 23 for external connection.

An assembled battery according to the fourth embodiment includes the battery according to the third embodiment. Therefore, it can exhibit high input/output performance and excellent storage performance.

[Fifth Embodiment]
According to a fifth embodiment, a battery pack is provided. This battery pack includes an assembled battery according to the fourth embodiment. This battery pack may comprise a single battery according to the third embodiment instead of the assembled battery according to the fourth embodiment.

The battery pack according to the fifth embodiment can further include a protection circuit. The protection circuit has a function of controlling charging and discharging of the battery. Alternatively, a circuit included in a device that uses a battery pack as a power source (for example, an electronic device, an automobile, etc.) may be used as a protection circuit for the battery pack.

Also, the battery pack according to the fifth embodiment can further include an external terminal for power supply. The energizing external terminal is for outputting current from the battery to the outside and/or for inputting current from the outside to the battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through the external terminals for power supply. Also, when charging the battery pack, a charging current (including regenerative energy from the power of an automobile or the like) is supplied to the battery pack through an external terminal for power supply.

Next, an example of a battery pack according to a fifth embodiment will be described with reference to the drawings.

FIG. 10 is an exploded perspective view schematically showing an example of a battery pack according to the fifth embodiment. 11 is a block diagram showing an example of an electric circuit of the battery pack shown in FIG. 10. FIG.

A battery pack 300 shown in FIGS. 10 and 11 includes a container 31, a lid 32, a protective sheet 33, an assembled battery 200, a printed wiring board 34, wiring 35, and an insulating plate (not shown). .

A storage container 31 shown in FIG. 10 is a bottomed rectangular container having a rectangular bottom surface. The storage container 31 is configured to be able to store the protective sheet 33 , the assembled battery 200 , the printed wiring board 34 , and the wiring 35 . Lid 32 has a rectangular shape. The lid 32 accommodates the assembled battery 200 and the like by covering the container 31 . Although not shown, the storage container 31 and the lid 32 are provided with openings, connection terminals, or the like for connection to external devices or the like.

The assembled battery 200 includes a plurality of single cells 100 , a positive lead 22 , a negative lead 23 , and an adhesive tape 24 .

At least one of the plurality of cells 100 is the battery according to the third embodiment. Each of the plurality of cells 100 is electrically connected in series as shown in FIG. The plurality of single cells 100 may be electrically connected in parallel, or may be connected in a combination of series connection and parallel connection. When a plurality of unit cells 100 are connected in parallel, the battery capacity increases compared to when they are connected in series.

The adhesive tape 24 fastens the plurality of unit cells 100 . Instead of the adhesive tape 24, heat-shrinkable tape may be used to fix the plurality of unit cells 100. FIG. In this case, after the protective sheets 33 are arranged on both sides of the assembled battery 200 and the heat-shrinkable tape is wrapped around, the heat-shrinkable tape is heat-shrunk to bind the plurality of unit cells 100 together.

One end of the positive lead 22 is connected to the assembled battery 200 . One end of the positive electrode lead 22 is electrically connected to the positive electrode of one or more cells 100 . One end of the negative lead 23 is connected to the assembled battery 200 . One end of the negative electrode lead 23 is electrically connected to the negative electrode of one or more cells 100 .

The printed wiring board 34 is installed along one short-side surface of the inner surface of the container 31 . The printed wiring board 34 includes a positive connector 342, a negative connector 343, a thermistor 345, a protection circuit 346, wirings 342a and 343a, an external terminal 350 for conducting electricity, and a positive wiring (positive wiring) 348a. and a negative wiring (negative wiring) 348b. One main surface of the printed wiring board 34 faces one side surface of the assembled battery 200 . An insulating plate (not shown) is interposed between the printed wiring board 34 and the assembled battery 200 .

The other end 22 a of the positive lead 22 is electrically connected to the positive connector 342 . The other end 23 a of the negative lead 23 is electrically connected to the negative connector 343 .

The thermistor 345 is fixed to one main surface of the printed wiring board 34 . The thermistor 345 detects the temperature of each cell 100 and transmits the detection signal to the protection circuit 346 .

An external terminal 350 for conducting electricity is fixed to the other main surface of the printed wiring board 34 . External terminal 350 for power supply is electrically connected to a device outside battery pack 300 . The external terminal 350 for energization includes a positive terminal 352 and a negative terminal 353 .

The protection circuit 346 is fixed to the other main surface of the printed wiring board 34 . The protection circuit 346 is connected to the positive terminal 352 via a positive wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via the negative wiring 348b. Also, the protection circuit 346 is electrically connected to the positive connector 342 via a wiring 342a. The protection circuit 346 is electrically connected to the negative connector 343 via wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the plurality of cells 100 via the wiring 35 .

The protective sheets 33 are arranged on both inner side surfaces in the long side direction of the container 31 and on the inner side surface in the short side direction facing the printed wiring board 34 with the assembled battery 200 interposed therebetween. The protective sheet 33 is made of resin or rubber, for example.

The protection circuit 346 controls charging and discharging of the plurality of cells 100 . In addition, based on the detection signal transmitted from the thermistor 345 or the detection signal transmitted from each unit cell 100 or the assembled battery 200, the protection circuit 346 and the external terminal for energizing the external device. 350 (positive terminal 352, negative terminal 353) is cut off.

Examples of the detection signal transmitted from the thermistor 345 include a signal that detects that the temperature of the unit cell 100 is equal to or higher than a predetermined temperature. Examples of detection signals transmitted from the individual cells 100 or the assembled battery 200 include signals that detect overcharge, overdischarge, and overcurrent of the cells 100 . When detecting overcharge or the like for each unit cell 100, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each single cell 100 .

As the protection circuit 346, a circuit included in a device (for example, an electronic device, an automobile, etc.) that uses the battery pack 300 as a power source may be used.

The battery pack 300 also has the external terminals 350 for power supply as described above. Therefore, the battery pack 300 can output current from the assembled battery 200 to an external device and input current from the external device to the assembled battery 200 via the external terminal 350 for power supply. In other words, when the battery pack 300 is used as a power source, current from the assembled battery 200 is supplied to the external device through the external terminals 350 for power supply. Also, when charging the battery pack 300 , a charging current from an external device is supplied to the battery pack 300 through the external terminal 350 for power supply. When this battery pack 300 is used as an on-vehicle battery, the regenerated energy of the motive power of the vehicle can be used as the charging current from the external device.

Note that the battery pack 300 may include a plurality of assembled batteries 200 . In this case, the plurality of assembled batteries 200 may be connected in series, may be connected in parallel, or may be connected in a combination of series connection and parallel connection. Also, the printed wiring board 34 and the wiring 35 may be omitted. In this case, the positive-side lead 22 and the negative-side lead 23 may be used as the positive-side terminal and the negative-side terminal, respectively, of the external terminals for electricity supply.

Such battery packs are used in applications that require excellent cycle performance when drawing a large current, for example. Specifically, this battery pack is used, for example, as a power supply for electronic equipment, a stationary battery, and a vehicle battery for various vehicles. Examples of electronic devices include digital cameras. This battery pack is particularly suitable for use as a vehicle battery.

A battery pack according to the fifth embodiment includes the battery according to the third embodiment or the assembled battery according to the fourth embodiment. Therefore, it can exhibit high input/output performance and excellent storage performance.

[Sixth Embodiment]
According to a sixth embodiment, a vehicle is provided. This vehicle is equipped with the battery pack according to the fifth embodiment.

In the vehicle according to the sixth embodiment, the battery pack recovers, for example, regenerative energy of power of the vehicle. The vehicle may include a mechanism (eg, regenerator) that converts the kinetic energy of the vehicle into regenerative energy.

Examples of vehicles according to the sixth embodiment include two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, assisted bicycles, and railway vehicles.

The mounting position of the battery pack in the vehicle according to the sixth embodiment is not particularly limited. For example, when the battery pack is installed in an automobile, the battery pack can be installed in the engine compartment of the vehicle, behind the vehicle body, or under the seat.

A vehicle according to the sixth embodiment may be equipped with a plurality of battery packs. In this case, the batteries included in each battery pack may be electrically connected in series, may be electrically connected in parallel, or may be electrically connected by combining series connection and parallel connection. good too. For example, when each battery pack includes an assembled battery, the assembled batteries may be electrically connected in series or may be electrically connected in parallel. may be connected to Alternatively, if each battery pack contains a single battery, the respective batteries may be electrically connected in series, electrically in parallel, or a combination of series and parallel connections. may be electrically connected.

Next, an example of a vehicle according to a sixth embodiment will be described with reference to the drawings.

FIG. 12 is a partially transparent view schematically showing an example of a vehicle according to the sixth embodiment.

A vehicle 400 shown in FIG. 12 includes a vehicle body 40 and a battery pack 300 according to the fifth embodiment. In the example shown in FIG. 12, vehicle 400 is a four-wheeled automobile.

This vehicle 400 may be equipped with a plurality of battery packs 300 . In this case, the batteries (eg, cells or assembled batteries) included in the battery pack 300 may be connected in series, connected in parallel, or connected in a combination of series connection and parallel connection.

FIG. 12 shows an example in which the battery pack 300 is installed in the engine room located in front of the vehicle body 40. As shown in FIG. As described above, battery pack 300 may be mounted, for example, in the rear of vehicle body 40 or under the seat. This battery pack 300 can be used as a power source for vehicle 400 . Also, this battery pack 300 can recover the regenerated energy of the power of the vehicle 400 .

Next, an embodiment of the vehicle according to the sixth embodiment will be described with reference to FIG. 13 .

FIG. 13 is a diagram schematically showing an example of a control system for an electrical system in a vehicle according to the sixth embodiment. A vehicle 400 shown in FIG. 13 is an electric vehicle.

A vehicle 400 shown in FIG. 13 includes a vehicle main body 40, a vehicle power supply 41, a vehicle ECU (ECU: Electric Control Unit) 42 that is a control device higher than the vehicle power supply 41, and external terminals (external A terminal 43 for connecting to a power supply, an inverter 44 and a drive motor 45 are provided.

A vehicle 400 is equipped with a vehicle power source 41, for example, in an engine room, in the rear of a vehicle body, or under a seat. In the vehicle 400 shown in FIG. 13, the locations where the vehicle power source 41 is mounted are schematically shown.

The vehicle power supply 41 includes a plurality (eg, three) of battery packs 300 a , 300 b and 300 c , a battery management unit (BMU) 411 , and a communication bus 412 .

The battery pack 300a includes an assembled battery 200a and an assembled battery monitoring device 301a (for example, VTM: Voltage Temperature Monitoring). The battery pack 300b includes an assembled battery 200b and an assembled battery monitoring device 301b. The battery pack 300c includes an assembled battery 200c and an assembled battery monitoring device 301c. Battery packs 300a to 300c are battery packs similar to battery pack 300 described above, and assembled batteries 200a to 200c are assembled batteries similar to assembled battery 200 described above. The assembled batteries 200a-200c are electrically connected in series. Battery packs 300 a , 300 b , and 300 c can be independently removed and replaced with another battery pack 300 .

Each of the assembled batteries 200a to 200c includes a plurality of cells connected in series. At least one of the plurality of cells is the battery according to the third embodiment. The assembled batteries 200a to 200c charge and discharge through the positive terminal 413 and the negative terminal 414, respectively.

The battery management device 411 communicates with the assembled battery monitoring devices 301a to 301c and collects information on the voltage, temperature, etc. of each of the cells 100 included in the assembled batteries 200a to 200c included in the vehicle power supply 41. do. Thereby, the battery management device 411 collects information on maintenance of the vehicle power source 41 .

The battery management device 411 and the assembled battery monitoring devices 301 a to 301 c are connected via a communication bus 412 . In communication bus 412, one set of communication lines is shared by a plurality of nodes (battery management device 411 and one or more assembled battery monitoring devices 301a to 301c). The communication bus 412 is, for example, a communication bus configured based on the CAN (Control Area Network) standard.

The assembled battery monitoring devices 301a to 301c measure the voltage and temperature of the individual single cells forming the assembled batteries 200a to 200c based on commands by communication from the battery management device 411. FIG. However, the temperature can be measured at only a few points per assembled battery, and it is not necessary to measure the temperature of all the single cells.

The vehicle power supply 41 can also have an electromagnetic contactor (for example, the switch device 415 shown in FIG. 13) that switches between the presence or absence of electrical connection between the positive terminal 413 and the negative terminal 414 . The switch device 415 includes a precharge switch (not shown) that is turned on when the battery packs 200a to 200c are charged, and a switch device that is turned on when the output from the battery packs 200a to 200c is supplied to the load. and a main switch (not shown). Each of the precharge switch and the main switch has a relay circuit (not shown) that is switched on or off by a signal supplied to a coil arranged near the switch element. Electromagnetic contactors such as the switch device 415 are controlled based on control signals from the battery management device 411 or the vehicle ECU 42 that controls the operation of the vehicle 400 as a whole.

The inverter 44 converts the input DC voltage into a three-phase alternating current (AC) high voltage for driving the motor. Three-phase output terminals of the inverter 44 are connected to respective three-phase input terminals of the drive motor 45 . The inverter 44 is controlled based on a control signal from the battery management device 411 or the vehicle ECU 42 for controlling the operation of the entire vehicle. By controlling the inverter 44, the output voltage from the inverter 44 is adjusted.

The drive motor 45 is rotated by power supplied from the inverter 44 . A driving force generated by the rotation of the driving motor 45 is transmitted to the axle and the driving wheels W via, for example, a differential gear unit.

In addition, although not shown, vehicle 400 includes a regenerative braking mechanism (regenerator). The regenerative braking mechanism rotates the drive motor 45 when the vehicle 400 is braked, and converts kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative brake mechanism is input to the inverter 44 and converted into direct current. The converted DC current is input to vehicle power source 41 .

One terminal of the connection line L<b>1 is connected to the negative terminal 414 of the vehicle power supply 41 . The other terminal of the connection line L1 is connected to the negative input terminal 417 of the inverter 44 . A current detection unit (current detection circuit) 416 in the battery management device 411 is provided between the negative terminal 414 and the negative input terminal 417 on the connection line L1.

One terminal of the connection line L2 is connected to the positive terminal 413 of the vehicle power source 41 . The other terminal of the connection line L2 is connected to the positive input terminal 418 of the inverter 44 . A switch device 415 is provided between the positive terminal 413 and the positive input terminal 418 on the connection line L2.

The external terminal 43 is connected to the battery management device 411 . The external terminal 43 can be connected to, for example, an external power supply.

The vehicle ECU 42 cooperatively controls the vehicle power source 41, the switch device 415, the inverter 44, and the like together with other management devices and control devices including the battery management device 411 in response to operation input by the driver or the like. The cooperative control of the vehicle ECU 42 and the like controls the output of electric power from the vehicle power supply 41, the charging of the vehicle power supply 41, and the like, and manages the vehicle 400 as a whole. Between the battery management device 411 and the vehicle ECU 42, data transfer related to the maintenance of the vehicle power source 41, such as the remaining capacity of the vehicle power source 41, is performed via a communication line.

A vehicle according to the sixth embodiment is equipped with the battery pack according to the fifth embodiment. High-performance vehicles can be provided because of the high input/output performance of the battery pack. Since the battery pack has excellent storage performance, highly reliable vehicles can be provided.

[Example]
EXAMPLES The above embodiments will be described in more detail below based on examples.

1. Solid electrolyte material <Synthesis>
(Examples A-1 to A-20)
An oxide having a perovskite structure represented by the general formula A(Mα _1-w Mβ _w )O ₃ was synthesized in the following manner.

First, raw materials were weighed so as to have a predetermined molar ratio and mixed in a mortar in order to obtain the target composition shown in Table 1 below. As specific examples of raw materials used, Sr(NO ₃ ) ₂ , Li ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ and TiO ₂ were used in Examples A-1 to A-6. Next, the mixture was calcined at a temperature of 800° C. for 12 hours. This calcined mixture was pulverized and mixed again. After that, the obtained pulverized mixed powder was uniaxially pressure-molded into a pellet (coin shape) having a thickness of 1 mm and a diameter of 12 mm. This pellet was sintered at a temperature of 1350° C. for 1 hour to obtain an oxide as a solid electrolyte material of Example A-6.

For Examples A-1 to A-5 and Examples A-7 to A-20, annealing treatment was performed in an oxygen atmosphere for each sample after main firing. The sample was placed in a tubular furnace that could be filled with atmospheric gas. After filling the interior of the furnace with pure oxygen gas, annealing treatment was performed at 600 ° C. for 12 hours while performing pure oxygen flow at 0.5 L / min, Examples A-1 to A-5 and Example A- 7 to A-20 were obtained as solid electrolyte materials.

(Comparative Examples A-1 to A-3)
An oxide was synthesized by the same procedure as in Example A-1, except that the raw materials were weighed so as to have a predetermined molar ratio to obtain the target composition shown in Table 2 below. In this way, oxides were obtained as solid electrolyte materials of Comparative Examples A-1 to A-3.

(Comparative Example A-4)
An oxide as a solid electrolyte material was obtained by the same procedure as in Comparative Example A-1, except that Ta ₂ O ₅ powder was added to the pulverized mixed powder before pellet molding.

(Examples B-1 to B-19)
An oxide having a NASICON structure represented by the general formula Li _x Mα _y (Mβ _1-z D _z )(PO ₄ ) ₃ was synthesized in the following manner.

First, in order to obtain the desired composition shown in Table 3 below, the raw materials were weighed to give a predetermined molar ratio and mixed in a mortar. As specific examples of raw materials used, Li ₂ CO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , BaCO ₃ , ZrO ₂ and NH ₄ H ₂ PO ₄ were used in Examples B-1 to B-6. To decompose the phosphate, the mixture was placed in an electric furnace and heated at 300° C. for 12 hours, then removed from the furnace and cooled at a cooling rate of 100° C./min.

Next, after re-pulverizing this mixture, it was calcined at a temperature of 800° C. for 12 hours. This calcined mixture was pulverized and mixed again. After that, the obtained pulverized mixed powder was uniaxially pressure-molded into a pellet (coin shape) having a thickness of 1 mm and a diameter of 12 mm. This pellet was sintered at a temperature of 1350° C. for 1 hour to obtain an oxide as a solid electrolyte material of Example B-6.

For Examples B-1 to B-5 and Examples B-7 to B-19, each sample after main firing was annealed in an oxygen atmosphere. The sample was placed in a tubular furnace that could be filled with atmospheric gas. After filling the interior of the furnace with pure oxygen gas, while performing pure oxygen flow at 0.5 L / min, annealing treatment was performed at 600 ° C. for 12 hours to obtain Examples B-1 to B-5 and Example B- 7 to B-19 were obtained as solid electrolyte materials.

(Comparative Examples B-1 to B-3)
An oxide was synthesized by the same procedure as in Example A-1, except that the raw materials were weighed so as to have a predetermined molar ratio in order to obtain the target composition shown in Table 4 below. In this way, oxides were obtained as solid electrolyte materials of Comparative Examples B-1 to B-3.

(Comparative Example B-4)
An oxide as a solid electrolyte material was obtained in the same manner as in Comparative Example B-1, except that Ta ₂ O ₅ powder was added to the pulverized mixed powder before pellet molding.

<Evaluation>
Both surfaces of the solid electrolyte material pellets obtained for each of the examples and comparative examples were polished to be smooth, and then the side surfaces of the pellets (coin-shaped edge portions) were covered with a masking tape. A blocking electrode was prepared by vapor-depositing gold on both sides of the pellet smoothed by polishing.

(Li ion conductivity measurement)
Next, in order to measure the Li ion conductivity of the synthesized solid electrolyte material, the blocking electrode prepared using each pellet was dried under vacuum at a temperature of 140° C. for 12 hours. The blocking electrode was then placed in a four-terminal measurement vessel filled with dry argon (Ar). The four-terminal measurement container containing the blocking electrode was placed in a constant temperature bath, held at the temperature set as the measurement condition for 2 hours, and then impedance was measured using an Impedance Analyzer 4192A manufactured by Yokogawa Hewlett-Packard. The set temperature for the measurement was 25°C. The measurement frequency range is from 5 Hz to 13 MHz, the resistance value of the bulk part is calculated from the measurement results of the complex impedance, and the electrode area and thickness of the pellet are used to determine the lithium ion conductivity σ _b (S / cm) in the bulk part. was calculated.

(Valence measurement and reduction resistance test)
For each solid electrolyte material, the valences of Nb and Ta in the oxide were measured by EPMA measurement by the method described above. The measurement results are shown in Table 1-4 below.

Next, a reduction resistance test was conducted to confirm whether the synthesized solid electrolyte material could maintain stability at a potential equivalent to that of metallic lithium. First, for the blocking electrodes using pellets of each solid electrolyte material, both sides of the pellets were polished with a #800 wrapping film (manufactured by 3M) to completely remove the gold electrodes. Using each pellet, one side of the pellet was brought into contact with a circular metallic lithium foil having a diameter of 10 mm for 1 hour in an argon atmosphere. After 1 hour, it was taken out from the argon atmosphere, and EPMA measurement was performed on the contact surface and the non-contact surface with metallic lithium. The differences in peaks before and after contact were compared, and when no difference due to reduction was observed, it was determined that there was no reduction, and when a difference was observed, it was determined that there was reduction. The determination results are shown in Table 1-4 below.

(Powder X-ray diffraction measurement)
The obtained sample was subjected to powder X-ray diffraction measurement as follows.

Each pellet was pulverized using a mortar and pestle to an average particle size of about 10 μm. The pulverized sample was filled in a holder portion with a depth of 0.2 mm formed on a glass sample plate. Then, another glass plate was used from the outside and pressed sufficiently to smooth it. Next, the glass plate filled with the sample was placed in a powder X-ray diffractometer, and a diffraction pattern was obtained using Cu—Kα rays. As a result of investigating the crystal phase and space group using the crystal structure analysis by the Rietveld method, it was confirmed that it had the intended crystal structure.

Specifically, it was confirmed that perovskite structures were obtained in Examples A-1 to A-20 and Comparative Examples A-1 to A-4 (Examples and Comparative Examples of the A series). Tables 1 and 2 show the crystal phase and space group of the oxide in each solid electrolyte material in the A series. For Examples B-1 to B-19 and Comparative Examples B-1 to B-4 (B series examples and comparative examples), it was confirmed that a NASICON type structure was obtained. Tables 3 and 4 show the crystal phase and space group of the oxide in each solid electrolyte material in the B series.

Tables 1-4 below summarize the details of the composition and crystal structure of the oxides of the solid electrolyte materials synthesized in Examples and Comparative Examples of the A Series and Examples and Comparative Examples of the B Series. As the composition, the chemical composition formula, the mass ratio α _Ta /α _Nb , the respective valences of Nb and Ta, the presence or absence and type of the main element Mβ _p , the presence or absence and type of the auxiliary element Mβ _s , and the auxiliary to Nb in the oxide The element ratio E _βs /E _Nb of the element Mβ _s is shown. As details of the crystal structure, main crystal phases and space groups of the main phases are shown. In all of the A series, an oxide having a perovskite crystal structure was obtained. In all of the B series, an oxide having a NASICON-type crystal structure was obtained.

Table 5 below summarizes the results of the Li ion conductivity measurement and the reduction resistance test for the solid electrolyte materials obtained in the Examples and Comparative Examples of the A series. Table 6 summarizes the results of the Li ion conductivity measurement and reduction resistance test for the solid electrolyte materials obtained in the Examples and Comparative Examples of the B series.

From the results in Table 5, including the metal element Mα composed of Nb and Ta, the octahedral coordination structure in which oxygen atoms are arranged around the metal element M is included, and the mass ratio _αTa / _αNb of Ta to Nb is 5×. It can be seen that the solid electrolyte material containing oxides in the range of 10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ has high Li ion conductivity and excellent resistance to reduction.

2. Batteries <Battery manufacturing>
In order to examine the discharge performance of the batteries using the solid electrolyte materials obtained in the respective examples and comparative examples, all-solid batteries were produced using the respective solid electrolyte materials. Specifically, a battery including a single-layer electrode body composed of positive electrode layer/electrolyte layer (composite electrolyte layer)/negative electrode layer having the configuration shown in FIG. 3 was produced.

As the positive electrode active material, LiMn _0.85 Fe _0.1 Mg _0.05 PO ₄ having an olivine structure in which carbon fine particles (average particle diameter 5 nm) are attached to the surface (adhesion amount 0.1% by mass) and the average particle diameter of the primary particles is 50 nm. particles were used. Vapor-grown carbon fibers with a fiber diameter of 0.1 μm as a conductive agent, graphite powder as a conductive agent, and PVdF as a binder were added to the positive electrode active material particles at a mass ratio of 100. :3:5:5 and dispersed in an n-methylpyrrolidone (NMP) solvent to prepare a slurry. After that, the resulting slurry was applied to one side of a 15 μm thick aluminum alloy foil (purity 99%). After drying the slurry coating, a positive electrode layer with a thickness of 67 μm was formed on one side of the current collector (aluminum alloy foil) through a pressing process, and the electrode density was 2.2 g/cm ³ (including the current collector). A positive electrode was fabricated.

As the negative electrode active material, the following oxide particles were used. In Example C-1, Li ₄ Ti ₅ O ₁₂ particles having an average particle diameter D ₅₀ =0.8 μm and a specific surface area of 10 m ² /g were used. In Example C-2, Li ₂ Na ₂ Ti ₆ O ₁₄ particles having an average particle diameter D ₅₀ of 0.6 μm and a specific surface area of 15 m ² /g were used. In Example C-3, Nb ₂ TiO ₇ particles having an average particle diameter D ₅₀ =1.0 μm and a specific surface area of 8 m ² /g were used. Graphite powder having an average particle size of 6 μm as a conductive agent and PVdF as a binder are blended with each of the negative electrode active material particles in a mass ratio of 95:3:2 to obtain n-methylpyrrolidone (NMP). It was dispersed in a solvent and stirred with a ball mill at a rotation speed of 1000 rpm for a stirring time of 2 hours to prepare a slurry. The resulting slurry was applied to a 15 μm thick aluminum alloy foil (purity 99.3%). A negative electrode was produced by drying the coating film of the slurry and passing through a hot press process. In this way, a negative electrode having an electrode density of 2.2 g/cm ³ (excluding the current collector) was produced, in which a negative electrode layer having a thickness of about 59 μm was formed on one side of the current collector (aluminum alloy foil). . The negative electrode porosity, excluding the current collector, was approximately 35%.

A composite electrolyte used for the electrolyte layer was prepared as follows. First, the solid electrolyte particles synthesized in Example A-12 were pulverized to a primary particle size (diameter) of 1 μm. A predetermined amount of the pulverized solid electrolyte particles was added to a gel-like polyacrylonitrile polymer containing a mixed solvent (volume ratio 1:2) of propylene carbonate (PC) and diethyl carbonate (DEC) in which 1.2 M of LiPF ₆ was dissolved. By mixing and compositing, an electrolyte layer of the composite electrolyte having a thickness of 2 μm is formed between the positive electrode layer of the positive electrode obtained as described above and the negative electrode layer of each of the negative electrodes obtained as described above. made. Here, the mass ratio of solid electrolyte particles, PC/DEC mixed solvent, and gel-like polyacrylonitrile polymer was adjusted to 96:3.2:0.8.

More specifically, in the electrolyte composite step, first, the solid electrolyte particles synthesized in Example A-12 were dispersed in a PVdF binder solution dissolved in an n-methylpyrrolidone (NMP) solution before gelation, and The dispersion was applied over the positive electrode layer and over the negative electrode layer. After drying the dispersion, it was added to a solution containing a PC/DEC mixed solvent (1:2 by volume) in which 1.2 M of LiPF ₆ was dissolved and a polyacrylonitrile (PAN) polymer (2% by mass). 2'-Azobis-4-methoxy-2,4-dimethylvaleronitrile was added as a radical agent for polymerization initiation, impregnating each electrode layer and the binder thereon, and heating to form a gelled composite. We were able to prepare an electrolyte. At this time, the amounts of organic components in the electrode layer and in the composite electrolyte were adjusted to 3% and 4% by mass, respectively. The mass ratio of the inorganic particles, the binder, and the organic component in the composite electrolyte is 94.3:1.9:3.8. The mass ratio of the organic electrolyte (PC/DEC solution of LiPF ₆ ) in the composite electrolyte was 3.0%. The single-layer lithium batteries (all-solid-state batteries) produced here were designated as Examples C-1 to C-3 according to the negative electrode active materials used as described above. Next, a single-layer lithium battery (all-solid battery) was produced in the same manner as in Example C-1 except that the solid electrolyte particles synthesized in Comparative Example A-1 was used, and this was used in Comparative Example C-1. and

Next, lithium batteries were produced in the same manner as in Examples C-1 to C-3, except that the solid electrolyte particles synthesized in Example B-12 were used, and Examples D-1 to D- 3. A lithium battery was prepared in the same manner as in Comparative Example C-1 except that the solid electrolyte particles synthesized in Comparative Example B-1 were used, and this was designated as Comparative Example D-1.

<Evaluation>
(Charge/discharge measurement)
For each of the lithium batteries produced in Examples C-1 to C-3 and Comparative Example C-1, and the lithium batteries produced in Examples D-1 to D-3 and Comparative Example D-1, under an environment of 25°C. A charge/discharge test was performed at The charging/discharging range in the charging/discharging test was determined for batteries using Li ₄ Ti ₅ O ₁₂ or Nb ₂ TiO ₇ as the negative electrode active material (Example C-1, Comparative Example C-1, Example D-1, and Comparative Example For D-1, Examples C-3, and D-3), the potential range was such that the potential of the negative electrode was 1.0 V or more and 1.7 V or less (vs. Li/Li ⁺ ). In the batteries using Li ₂ Na ₂ Ti ₆ O ₁₄ as the negative electrode active material (Examples C-2 and D-2), the potential of the negative electrode was 1.0 V or more and 3.0 V or less (vs. Li/Li ⁺ ). The charge/discharge current value when confirming the capacity was set to 0.01 C (discharge rate per hour) at a temperature of 25°C, and the discharge capacity at that time was taken as the reference capacity (100%). Next, charge and discharge were performed at 0.1C under a temperature condition of 25°C, and the 0.1C discharge capacity retention rate with respect to the above reference capacity was calculated (0.1C discharge capacity retention rate = [0.1C discharge capacity retention rate at 25°C). 1C discharge capacity]/[reference capacity]).

(Storage test)
A storage test was performed on each battery.

First, each battery was charged at a constant current of 0.01 C in an environment of 25°C. The battery after charging was held in an environment of 25° C. for 24 hours. Each cell was then discharged at a constant current of 0.01C. The discharge capacity obtained by this discharge was taken as the post-storage discharge capacity. The post-storage discharge capacity retention rate of the post-storage discharge capacity with respect to the reference capacity was calculated (post-storage discharge capacity retention rate = [post-storage discharge capacity]/[reference capacity]).

Table 7 below shows the structure of the electrode bodies of the lithium batteries produced in Examples C-1 to C-3 and Comparative Example C-1, the results of the charge test, and the results of the storage test.

Table 8 below shows the structure of the electrode bodies of the lithium batteries produced in Examples D-1 to D-3 and Comparative Example D-1, the results of the charge test, and the results of the storage test.

As shown in Table 7, the lithium batteries produced in Examples C-1 to C-3 had a 0.1C discharge capacity retention rate of 90% or more with respect to the reference capacity (0.01C rate discharge at 25 ° C.). Indicated. These batteries maintained a discharge capacity retention rate of 89% or more after storage. In contrast, the lithium battery produced in Comparative Example C-1 had a low 0.1C discharge capacity retention rate. The discharge capacity retention rate after storage was also low.

As shown in Table 8, in the lithium batteries produced in Examples D-1 to D-3, the discharge capacity retention rate at a high rate of 88% or more with respect to the reference capacity (0.01C rate discharge at 25 ° C.) showed that. These batteries maintained a discharge capacity retention rate of 87% or more after storage. In contrast, the lithium battery produced in Comparative Example D-1 had a low 0.1C discharge capacity retention rate.
The discharge capacity retention rate after storage was also low.

From the test results, it was found that a battery having excellent input/output performance and storage performance can be obtained by using the solid electrolyte material according to the embodiment.

According to one or more embodiments and examples described above, a solid electrolyte material is provided. This solid electrolyte material contains an oxide containing an octahedral coordination structure containing a metal element M and oxygen atoms arranged in the center of the metal element M. The metal element M contains Nb and Ta. The mass ratio α _Ta /α _Nb between the mass α _Nb of Nb and the mass α _Ta of Ta is within the range of 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ . With this configuration, the solid electrolyte material has excellent resistance to reduction and exhibits high ionic conductivity. It is also possible to provide an electrode capable of realizing a battery with high input/output performance and excellent storage performance, a battery and battery pack with high input/output performance and excellent storage performance, and a vehicle equipped with this battery pack.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.
The invention described in the original claims of the present application is appended below.
[1] Containing an octahedral coordination structure containing a metal element M and an oxygen atom arranged at the center of the metal element M, the metal element M containing Nb and Ta, the mass α Nb of the Nb and _the Ta A solid electrolyte material containing an oxide having _a mass ratio α Ta _/ α _Nb to the mass α Ta of 5×10 ⁻⁵ ≦α _Ta /α _Nb ≦3×10 ⁻³ .
[2] The solid electrolyte material according to [1], wherein the metal element M further includes at least one metal element Mβ selected from the group consisting of Ti, Zr, Ga, Ge, Si, Fe, and P.
[3] The metal element M includes an auxiliary element _Mβs selected from the group consisting of Si, Fe, and P among the metal elements Mβ, and the element of the auxiliary element Mβs relative to the element abundance ratio E Nb _of the _Nb The solid electrolyte material according to [2], wherein the element ratio E βs /E Nb of _the abundance _ratio E _βs is 1×10 ⁻⁴ or more and 5×10 ⁻³ or less.
[4] The solid electrolyte material according to any one of [1] to [3], wherein the crystal structure of the oxide includes at least one selected from the group consisting of a perovskite structure and a NASICON structure.
[5] The oxide has the perovskite structure, is represented by the general formula A(Mα _1-w Mβ _w )O _{3 ,} w is in the range of 0≦w<1, and Li and vacancies are present at the A site. The solid electrolyte material according to [4], wherein Mα contains the Nb and the Ta.
[6] The solid electrolyte material according to [5], wherein the oxide further contains at least one selected from the group consisting of La, Sr, Mg, Na, K, and Ca at the A site.
[7] The oxide has the NASICON structure, the NASICON structure includes at least one selected from the group consisting of a rhombohedral structure and a monoclinic structure, and the oxide has the general formula Li _x Mα _y (Mβ _1-z D _z )(PO ₄ ) ₃ , where Mα includes Nb and Ta, D is at least one selected from the group consisting of Ca, Sr, and Ba, and x is within the range of 0<x≦2, y is within the range of 0<y≦1, and z is within the range of 0≦z≦1, the solid electrolyte material according to [4].
[8] An electrode comprising the solid electrolyte material according to any one of [1] to [7].
[9] The electrode according to [8], further comprising an active material capable of intercalating/deintercalating lithium ions.
[10] a positive electrode layer capable of intercalating and deintercalating lithium ions;
a negative electrode layer capable of intercalating and deintercalating lithium ions;
a Li conductive layer capable of conducting lithium ions;
A battery in which at least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer comprises the solid electrolyte material according to any one of [1] to [7].
[11] At least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer includes a composite electrolyte containing the solid electrolyte material and an organic electrolyte, and the mass ratio of the organic electrolyte in the composite electrolyte is 0.5. The battery according to [10], which is 1% or more and 20% or less.
[12] A battery pack comprising the battery according to [10] or [11].
[13] an external terminal for energization;
protection circuit and
The battery pack according to [12], further comprising:
[14] comprising a plurality of the batteries,
The battery pack of [12] or [13], wherein the batteries are electrically connected in series, in parallel, or in a combination of series and parallel.
[15] A vehicle equipped with the battery pack according to any one of [12] to [14].
[16] The vehicle according to [15], including a mechanism for converting kinetic energy of the vehicle into regenerative energy.

1 Li ion, 2 Oxygen atom, 3 A site ion, 4 Atom, 5 MO ₆ octahedron, 6 Octahedral site, 7 Tetrahedral site, 8 Negative electrode terminal, 9 Positive electrode terminal, 10A, DESCRIPTION OF SYMBOLS 10B, 10C... Electrode body 11... Positive electrode layer 12... Electrolyte layer 13... Negative electrode layer 14... Current collector 21... Bus bar 22... Positive electrode side lead 23... Negative electrode side lead 24... Adhesive tape 31 Container 32 Lid 33 Protective sheet 34 Printed wiring board 35 Wiring 40 Vehicle body 41 Vehicle power supply 42 Electric control device 43 External terminal 44 Inverter 45 Drive motor 100 Battery 101 Exterior member 121, 121A, 121B Inorganic solid particles 122 Organic electrolyte 123 Composite electrolyte 200 Assembled battery 200a Assembled battery 200b Assembled battery 200c Assembled battery 300 Battery pack 300a Battery pack 300b Battery pack 300c Battery pack 301a Assembled battery monitoring device 301b Assembled battery monitoring device 301c Assembled battery monitoring device 342 Positive connector 343 Negative connector 345 Thermistor 346 Protective circuit 342a Wiring 343a Wiring 350 External terminal for energization 352 Positive terminal 353 Negative terminal 348a Plus wiring 348b Negative side wiring 400 Vehicle 411 Battery management device 412 Communication bus 413 Positive electrode terminal 414 Negative electrode terminal 415 Switch device 416 Current detector 417 Negative input terminal 418 Positive electrode Input terminal, L1...connection line, L2...connection line, W...driving wheel.

Claims (12)

It contains an octahedral coordination structure containing a metal element M and an oxygen atom centered on the metal element M, wherein the metal element M contains the metal element Mα or the metal element Mα and the metal element Mβ, and the metal element Mα contains Nb and Ta, the metal element Mβ contains at least one selected from the group consisting of Ti, Zr, Ga, Ge, Si, Fe, and P, and the mass α of _Nb and the Ta including an oxide having a mass ratio α _Ta /α _Nb to the mass α Ta of within the range of 5 × 10 ^-5 ≤ α _Ta /α _Nb ≤ ₃ × 10 ^-3 ,
The crystal structure of the oxide includes at least one selected from the group consisting of a perovskite structure and a NASICON structure,
The oxide having a perovskite structure is represented by the general formula A(Mα _1-w Mβ _w )O ₃ , w is in the range of 0≦w<1, and contains Li and vacancies at the A site,
The NASICON structure includes at least one selected from the group consisting of a rhombohedral structure and a monoclinic structure, and the oxide having the NASICON structure has the general formula Li x Mα y (Mβ ₁ - _z D _z ) ₍ PO ₄ ) represented by ₃ , D is at least one selected from the group consisting of Ca, Sr, and Ba, x is in the range of 0<x≦2, and y is in the range of 0<y≦1 and z is in the range 0≦z≦1 . The metal element M includes an auxiliary element _Mβs selected from the group consisting of Si, Fe, and P among the metal elements Mβ, and the element abundance ratio E of the auxiliary element _Mβs with respect to the element abundance ratio E _Nb of Nb 2. The solid electrolyte material according to claim 1 , wherein the element ratio E _βs /E _Nb of _βs is 1×10 ⁻⁴ or more and 5×10 ⁻³ or less. 3. The oxide according to claim 1, wherein said oxide has said perovskite structure and further contains at least one selected from the group consisting of La, Sr, Mg, Na, K, and Ca at said A site . Solid electrolyte material. An electrode comprising the solid electrolyte material according to any one of claims 1 to 3 . 5. The electrode according to claim 4 , further comprising an active material capable of intercalating and deintercalating lithium ions. a positive electrode layer capable of intercalating and deintercalating lithium ions;
a negative electrode layer capable of intercalating and deintercalating lithium ions;
a Li conductive layer capable of conducting lithium ions;
A battery, wherein at least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer comprises the solid electrolyte material according to any one of claims 1 to 3 . At least one of the positive electrode layer, the negative electrode layer, and the Li conductive layer includes a composite electrolyte containing the solid electrolyte material and an organic electrolyte, and the mass ratio of the organic electrolyte in the composite electrolyte is 0.1% or more. 7. The battery according to claim 6 , which is 20% or less. A battery pack comprising the battery according to claim 6 or 7 . an external terminal for energization;
9. The battery pack of claim 8 , further comprising: a protection circuit; comprising a plurality of said batteries,
10. The battery pack of claim 8 or 9 , wherein the batteries are electrically connected in series, in parallel, or in a combination of series and parallel. A vehicle equipped with the battery pack according to any one of claims 9 to 10 . 12. The vehicle of claim 11 , including a mechanism for converting kinetic energy of the vehicle into regenerative energy.

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