Negative electrode material and battery

文档序号：890021 发布日期：2021-02-23 浏览：16次中文

阅读说明：本技术 负极材料以及电池 (Negative electrode material and battery ) 是由大岛龙也佐佐木出西山诚司河濑觉于 2019-10-10 设计创作，主要内容包括：本公开提供能够使电池的充放电效率提高的负极材料。一种负极材料(1000),包含第1固体电解质材料的还原体(101)和导电助剂(103)。第1固体电解质材料(101)采用式(1)：Li-αM-βX-γ表示。在此,在式(1)中,α、β和γ均为大于0的值,M为选自Li以外的金属元素和半金属元素之中的至少一种元素,并且,X为选自F、Cl、Br和I之中的至少一种元素。(Disclosed is a negative electrode material which enables the charge/discharge efficiency of a battery to be improved. A negative electrode material (1000) comprises a reducing agent (101) of a 1 st solid electrolyte material and a conductive auxiliary agent (103). The 1 st solid electrolyte material (101) adopts the formula (1): li α M β X γ And (4) showing. Here, in formula (1), α, β, and γ are each a value greater than 0, M is at least one element selected from among metal elements other than Li and semimetal elements, and X is at least one element selected from among F, Cl, Br, and I.)

1. A negative electrode material comprises 1 st solid electrolyte material reduction agent and conductive auxiliary agent,

the 1 st solid electrolyte material is represented by the following formula 1,

Li_αM_βX_γa 1. formula

Wherein, in the formula 1,

alpha, beta and gamma are all values greater than 0,

m is at least one element selected from the group consisting of metal elements other than Li and semimetal elements, and,

x is at least one element selected from F, Cl, Br and I.

2. The negative electrode material according to claim 1,

in an X-ray diffraction pattern of the reducing agent obtained by X-ray diffraction measurement using Cu-K alpha rays as a radiation source, a peak top exists in a range where a value of a diffraction angle 2 theta is theta a or more and theta b or less,

the θ b is a value reflecting a diffraction angle 2 θ of a peak top of a peak of a (220) plane of LiX formed by Li and the X,

the θ a is a value of a diffraction angle 2 θ derived from a peak top of a peak of the 1 st solid electrolyte material, and is a value closest to the θ b.

3. The anode material according to claim 1 or 2,

the 1 st solid electrolyte material satisfies:

1.5≤α≤4.5、

beta is more than or equal to 0.5 and less than or equal to 1.5 and

γ＝6。

4. the negative electrode material according to any one of claims 1 to 3,

the 1 st solid electrolyte material satisfies a relationship of α + m β ═ γ,

wherein M is the valence of M.

5. The negative electrode material according to any one of claims 1 to 4,

the M contains at least one element selected from transition metal elements.

6. The negative electrode material according to claim 5,

the M comprises yttrium.

7. The negative electrode material according to claim 6,

the 1 st solid electrolyte material is represented by the following formula 2,

Li_aMe_bY_cX₆a. formula 2

Wherein, in the formula 2,

a. b and c satisfy a + m_eb +3c is 6 and c > 0,

me is at least one element selected from the group consisting of metal elements other than Li and Y and semimetal elements,

m_eis the valence of said Me.

8. The negative electrode material according to any one of claims 1 to 7,

the conductive aid comprises acetylene black.

9. The negative electrode material according to any one of claims 1 to 8,

and a 2 nd solid electrolyte material, wherein,

the reduction potential with respect to lithium of the 2 nd solid electrolyte material is lower than the reduction potential with respect to lithium of the 1 st solid electrolyte material.

10. The negative electrode material according to claim 9,

the 2 nd solid electrolyte material contains a sulfide solid electrolyte material.

11. The negative electrode material according to claim 10,

the sulfide solid electrolyte material contains Li₂S-P₂S₅。

12. A battery is provided with:

a negative electrode comprising the negative electrode material according to any one of claims 1 to 11;

a positive electrode; and

an electrolyte layer disposed between the negative electrode and the positive electrode.

Technical Field

The present disclosure relates to an anode material and a battery.

Background

Non-patent document 1 discloses an all-solid lithium ion battery using a sulfide solid electrolyte material as a negative electrode material.

Prior art documents

Non-patent document

Non-patent document 1, F.Han et al, "A Battery Made from Single Material", adv.Mater.27(2015), 3473 to 3483

Disclosure of Invention

In the prior art, further improvement in charge and discharge efficiency of a battery has been desired.

The negative electrode material in one embodiment of the present disclosure includes a reduction agent of a 1 st solid electrolyte material and a conductive auxiliary agent, the 1 st solid electrolyte material is represented by the following formula (1),

Li_αM_βX_γthe formula (1)

Here, in the above formula (1), α, β, and γ are each a value larger than 0, M is at least one element selected from among metal elements other than Li and semimetal elements, and X is at least one element selected from among F, Cl, Br, and I.

According to the present disclosure, the charge/discharge efficiency of the battery can be improved.

Drawings

FIG. 1 shows Li as an example of a reduction agent of the 1 st solid electrolyte material_2.7Y _1.1Cl ₆A graph of the X-ray diffraction pattern of the reduced form of (c).

Fig. 2 is a cross-sectional view showing a schematic configuration of a negative electrode material 1000 that is an example of the negative electrode material in embodiment 1.

Fig. 3 is a cross-sectional view showing a schematic configuration of a battery 2000 as an example of the battery in embodiment 2.

Detailed Description

Embodiments of the present disclosure are described below with reference to the drawings.

(embodiment mode 1)

The negative electrode material in embodiment 1 includes a reducing agent (hereinafter also referred to as "halide reducing agent") of the 1 st solid electrolyte material (hereinafter also referred to as "halide solid electrolyte material") and a conductive assistant. The halide solid electrolyte material is a material represented by the following formula (1).

Li_αM_βX_γThe formula (1)

Here, in the above formula (1), α, β, and γ are all values larger than 0. Further, M is at least one element selected from metal elements other than Li and semimetal elements. X is at least one element selected from F, Cl, Br and I.

The "semimetal element" refers to B, Si, Ge, As, Sb and Te.

The "metal element" means:

(i) all elements contained in groups 1 (column 1) to 12 (column 12) of the periodic table of the elements except hydrogen, and

(ii) all elements contained in groups 13 (column 13) to 16 (column 16) of the periodic table except for B, Si, Ge, As, Sb, Te, C, N, P, O, S and Se. That is, the "metal element" refers to an element group which can become a cation when forming an inorganic compound with a halide.

The negative electrode material of embodiment 1 can improve the charge/discharge efficiency of the battery with the above configuration. The charge/discharge efficiency is obtained by the following equation.

Charge-discharge efficiency (%) (discharge capacity/charge capacity) × 100

As described above, non-patent document 1, which is described in the "background art" item, discloses a battery in which a reduction product of a sulfide solid electrolyte material (hereinafter also referred to as "sulfide reduction product") is used as a negative electrode material. The inventors of the present invention conducted extensive studies and found that: a battery using a sulfide-reduced product as a negative electrode material has a problem that the charge/discharge efficiency of the battery is low due to the electron conductivity and ion conductivity of the sulfide-reduced product, and the like. The halide reducer exhibits good electron conductivity and ion conductivity. That is, the negative electrode material of embodiment 1 contains a halide reductant exhibiting good electron conductivity and ion conductivity and a conductive auxiliary agent that assists electron conductivity, and therefore, can improve the charge and discharge efficiency of the battery.

The halide solid electrolyte material in embodiment 1 can also satisfy 1. ltoreq. alpha.ltoreq.5, 0. beta. ltoreq.2, and 5.5. ltoreq. gamma. ltoreq.6.5 in the above formula (1).

In addition, the halide solid electrolyte material in embodiment 1 may satisfy 1.5 ≦ α ≦ 4.5, 0.5 ≦ β ≦ 1.5, and γ ═ 6 in formula (1).

The halide solid electrolyte material in embodiment 1 may satisfy, for example, the formula (1) described above, where α is 2.7, β is 1.1, and γ is 6.

With the above configuration, the charge/discharge efficiency of the battery can be further improved.

The halide solid electrolyte material in embodiment 1 may satisfy the relationship of α + m β ═ γ in the above formula (1). Here, M is the valence of M. When M includes a plurality of elements, M β is the total of the composition ratios of the elements multiplied by the valence number of the elements. For example, M contains an element M1 and an element M2, and the composition ratio of the element M1 is β₁The valence of the element M1 is M₁The composition ratio of the element M2 is beta₂The valence of the element M2 is M₂In the case of (1), m β ═ m₁β₁+m₂β₂. In addition, when a plurality of valences of the element M are conceivable, the above relational expression may be satisfied when those conceivable valences are used as M.

With the above configuration, the charge/discharge efficiency of the battery can be further improved.

In the above formula (1), M may contain at least one element selected from transition metal elements.

With the above configuration, the charge/discharge efficiency of the battery can be further improved.

In the above formula (1), M may include yttrium (═ Y). That is, the halide solid electrolyte material may contain Y as the metal element.

The halide solid electrolyte material containing Y can be represented by, for example, the following formula (2).

Li_aMe_bY_cX₆The type (2)

Here, in the above formula (2), a, b and c satisfy a + m_eb +3c ═ 6, and c > 0, Me is at least one element selected from among metal elements and semimetal elements other than Li and Y. In addition, m_eThe valence of Me. Further, in the case where Me contains a plurality of elements, m_eb is the sum of the values obtained by multiplying the composition ratio of each element by the valence number of the element. For example, Me contains the elements Me1 and Me2, and the composition ratio of Me1 is b₁The valence of the element Me1 is m_e1The composition ratio of the element Me2 is b₂The valence of the element Me2 is m_e2In the case of (2), m_eb＝m_e1b₁+m_e2b₂. Me1 may be at least one member selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta and Nb. In addition, when a plurality of valences of the element Me are conceivable, the conceivable valences are defined as m_eWhen used, the above relational expression may be satisfied.

In the case where the halide solid electrolyte material satisfies the above formula (2) among the negative electrode materials in embodiment 1, the charge-discharge efficiency of the battery can be further improved.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (3).

Li_6-3dY_dX₆The type (3)

Here, in the composition formula (3), X is two or more elements selected from Cl, Br, and I. In the composition formula (3), d satisfies 0< d < 2.

When the halide solid electrolyte material satisfies the above formula (3) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, since the halide solid electrolyte material satisfying the above formula (3) has high ion conductivity, a halide reducing agent can be efficiently produced.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (4).

Li₃YX₆The type (4)

In the composition formula (4), X is two or more elements selected from Cl, Br and I. That is, in the above composition formula (3), d may be 1.

When the halide solid electrolyte material satisfies the above formula (4) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (4) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (5).

Li_3-3δY_1+δCl₆The type (5)

Here, in the composition formula (5), 0< δ ≦ 0.15 is satisfied.

When the halide solid electrolyte material satisfies the above formula (5) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (5) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (6).

Li_3-3δY_1+δBr₆The type (6)

Here, in the composition formula (6), 0< δ ≦ 0.25 is satisfied.

When the halide solid electrolyte material satisfies the above formula (6) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (6) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (7).

Li_3-3δ+aY_1+δ-aMe_aCl_6-x-yBr_xI_yThe type (7)

Here, in the composition formula (7), Me is at least one element selected from Mg, Ca, Sr, Ba, and Zn. Further, in the composition formula (7), the following are satisfied:

-1<δ<2、

0<a<3、

0<(3-3δ+a)、

0<(1+δ-a)、

0≤x≤6、

y is 0. ltoreq. y.ltoreq.6, and

(x+y)≤6。

when the halide solid electrolyte material satisfies the above formula (7) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (7) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (8).

Li_3-3δY_1+δ-aMe_aCl_6-x-yBr_xI_yThe type (8)

Here, in the composition formula (8), Me is at least one element selected from among Al, Sc, Ga, and Bi. Further, in the composition formula (8), the following are satisfied:

-1<δ<1、

0<a<2、

0<(1+δ-a)、

0≤x≤6、

y is 0. ltoreq. y.ltoreq.6, and

(x+y)≤6。

when the halide solid electrolyte material satisfies the above formula (8) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (8) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (9).

Li_3-3δ-aY_1+δ-aMe_aCl_6-x-yBr_xI_yThe type (9)

Here, in the composition formula (9), Me is at least one element selected from among Zr, Hf and Ti. Further, in the composition formula (9), the following are satisfied

-1<δ<1、

0<a<1.5、

0<(3-3δ-a)、

0<(1+δ-a)、

0≤x≤6、

Y is 0. ltoreq. y.ltoreq.6, and

(x+y)≤6。

when the halide solid electrolyte material satisfies the above formula (9) among the negative electrode materials in embodiment 1, the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (9) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

The halide solid electrolyte material in embodiment 1 may be a material represented by the following composition formula (10).

Li_3-3δ-2aY_1+δ-aMe_aCl_6-x-yBr_xI_yThe type (10)

Here, in the composition formula (10), Me is at least one element selected from Ta and Nb. Further, in the composition formula (10), the following are satisfied

-1<δ<1、

0<a<1.2、

0<(3-3δ-2a)、

0<(1+δ-a)、

0≤x≤6、

Y is 0. ltoreq. y.ltoreq.6, and

(x+y)≤6。

when the halide solid electrolyte material of the negative electrode material in embodiment 1 satisfies the above formula (10), the negative electrode material in embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the halide solid electrolyte material satisfying the above formula (10) has high ion conductivity, and therefore can efficiently generate a halide reducing agent.

Specific examples of the halide solid electrolyte material in embodiment 1 include, for example, Li_2.7Y_1.1Cl₆、Li₃YBr₃Cl₃、Li₃YBr₆、Li_2.5Zr_0.5Y_0.5Cl₆、Li₃YBr₂Cl₂I₂、Li_3.1Y_0.9Ca_0.1Cl₆、Li₃Y_0.8Al_0.2Cl₆、Li_2.5Y_0.5Hf_0.5Cl₆、Li_2.8Y_0.9Ta_0.1Cl₆、Li_4.5Y_0.475Bi_0.025Cl₆、Li_1.5Y_1.425Bi_0.075Cl₆And the like.

When the materials exemplified above are used as the halide solid electrolyte material in the negative electrode material of embodiment 1, the negative electrode material of embodiment 1 can improve the cycle characteristics of the battery and can also improve the charge/discharge efficiency of the battery. Further, the materials exemplified above have high ion conductivity, and therefore can efficiently generate a halide reducing agent.

As the halide solid electrolyte material in embodiment 1, in addition to the above, for example, a material satisfying the above formula (1) among known solid electrolyte materials can be used.

The halide reducing agent in embodiment 1 may have a peak top (peak top) in an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu — K α rays as a radiation source in a range where the value of the diffraction angle 2 θ is θ a or more and θ b or less.

Here, θ b is a value reflecting the diffraction angle 2 θ of the peak top of the peak of the (220) plane of LiX formed by Li and halogen (═ X) contained in the halide reducing agent. The peak of the (220) plane of LiX is a peak due to the (220) plane in the miller index hkl of a rock-salt structure having a crystal structure belonging to the space group Fm-3m, such as LiCl, LiBr, and LiI. When two or more kinds of halogens are contained in the halide reducer, a halogen having a smaller atomic number is selected as the halogen for determining θ b.

In addition, θ a is a value of the diffraction angle 2 θ derived from the peak top of the peak of the halide solid electrolyte material, and is the value closest to the above θ b.

With the above configuration, the negative electrode material in embodiment 1 can further improve the charge/discharge efficiency of the battery. Specifically, the peak derived from the halide reduction agent shifts from θ a to θ b with Li occlusion. On the other hand, the peak derived from the halide reducing agent shifts from θ b to θ a with Li release. It is believed that the crystal structure of the halide reductant shrinks and expands with Li occlusion and release. Therefore, it is presumed that the negative electrode material containing the halide reduction improves charge and discharge efficiency.

Here, Li, which is an example of a reduction product of the halide solid electrolyte material, is exemplified_2.7Y_1.1Cl₆By way of example, the X-ray diffraction patterns of the halide solid electrolyte material and the reduced product thereof were confirmed. Furthermore, Li_2.7Y_1.1Cl₆Is a halide solid electrolyte material used in example 1 described later. Hereinafter, Li may be mentioned_2.7Y_1.1Cl₆Is described as "LYC".

LYC was prepared by the same method as described in example 1. In addition, a glass-ceramic solid electrolyte material Li was also produced in the same manner as in example 2₂S-P₂S₅(hereinafter, also referred to as "LPS").

First, 0.44mol of LPS and 0.022mol of LYC were laminated in this order in an insulating outer tube. The resulting laminate was press-molded at a pressure of 370MPa to obtain an LPS-LYC laminate. A working electrode composed of LYC was obtained by placing stainless steel stitches on the LYC in the laminate.

Next, an In — Li alloy was produced by stacking metal In (thickness 200 μm), metal Li (thickness 300 μm), and metal In (thickness 200 μm) In this order In contact with LPS In the stack, and pressure-molding them at a pressure of 80 MPa. By disposing stainless pins on the In-Li alloy, a reference electrode and a counter electrode made of the In-Li alloy were obtained. Thus, a two-pole electrochemical cell made of SUS | LYC | LPS | In-Li alloy was obtained.

Next, the inside of the insulating outer tube is sealed by using an insulating collar while being blocked from the outside atmosphere.

Finally, the electrochemical cell was restrained from above and below by 4 bolts, thereby applying a surface pressure of 150MPa to the electrochemical cell.

By the above steps, an electrochemical cell for producing a reduced form of LYC was produced.

Using the above electrochemical cell, a reduced form of LYC (hereinafter referred to as "red-LYC") was produced under the following conditions.

The electrochemical cell was placed in a thermostat at 70 ℃. Then, the current value was set to 0.1mA/cm²When a current amount of 1 electron coulometric amount with respect to 1 molecule LYC is applied to the electrochemical cell, the working electrode obtained by terminating the application of the current is used as a red-LYC (1e charge) sample, and when a current amount of 2 electron coulometric amount with respect to 1 molecule LYC is applied, the working electrode obtained by terminating the application of the current is used as a red-LYC (2e charge) sample. The current value was set at 0.1mA/cm²The current density of (a) applies a current to the electrochemical cell, thereby lowering the potential of the working electrode to-0.6 v (vs liln), the working electrode of the electrochemical cell being used as a red-LYC (fully charged) sample.

In addition, the current value was 0.1mA/cm²An electrochemical cell in which the potential of the working electrode was lowered to-0.6V (vs LiIn) at a current density of (1), and a current value of 0.1mA/cm was inversely applied²When a current amount of 1 electron charge to LYC was applied, the working electrode obtained by terminating the current application was used as a red-LYC (1e discharge) sample. In addition, the current value was 0.1mA/cm²An electrochemical cell in which the potential of the working electrode was lowered to-0.6V (vs LiIn) at a current density of (1), and a current value of 0.1mA/cm was inversely applied²The current density of (a) applies a current, thereby increasing the potential of the working electrode to 1.9v (vs liin) as a red-LYC (fully discharged) sample.

FIG. 1 is a diagram showing an X-ray diffraction pattern of a red-LYC sample. The results shown in FIG. 1 were measured by the following method.

The X-ray diffraction pattern of red-LYC was measured in a dry environment with a dew point of-50 ℃ or lower using a fully automated multifunctional X-ray diffraction apparatus (RIGAKU, SmartLab). As the X-ray source, Cu-K.alpha.1 rays are used. That is, Cu-Ka radiation (wavelength) is usedI.e., 0.15405nm) was used as an X-ray, and the X-ray diffraction pattern was measured by the θ -2 θ method.

The peak top of the X-ray diffraction peak of red-LYC is present between the peak top position of the X-ray diffraction peak derived from LYC (i.e., the position of θ a) and the peak top position of LiCl (i.e., the position of θ b). The peak of LiCl shown in fig. 1 is described based on data loaded in an Inorganic Crystal Structure Database (ICSD) (ICSD No. 26909).

As shown in fig. 1, the X-ray diffraction peak of red-LYC shifts from the peak top position of the X-ray diffraction peak derived from LYC (i.e., the position of θ a) to the peak top position of the peak of LiCl (i.e., the position of θ b) with charge (Li occlusion), and shifts from the peak top position of the X-ray diffraction peak of LiCl to the peak top position of the peak of LYC with discharge (Li release).

The shape of the halide reducing agent in embodiment 1 is not particularly limited. The halide reducer may be in the form of, for example, needles, spheres, ellipsoids, etc. For example, the halide reducing agent may be in the form of particles.

The method for producing the halide reductase is not particularly limited, and a known method capable of reducing a halide solid electrolyte material can be used. For example, an electrochemical method can be mentioned. For example, an electrochemical cell using a Li-containing compound for the counter electrode and a halide solid electrolyte material for the working electrode is prepared in the same manner as the method for producing LYC. By sweeping a constant current in the cell, the halide solid electrolyte material of the working electrode is reduced, enabling the production of halide reducing agents.

Examples of the conductive aid contained in the negative electrode material of embodiment 1 include graphite such as natural graphite and artificial graphite, carbon black such as acetylene black and ketjen black, conductive fibers such as carbon fibers and metal fibers, fluorocarbon, metal powder such as aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxide such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene. When a carbon-based material is used as the conductive additive, cost reduction can be achieved.

In the anode material in embodiment 1, the conductive auxiliary agent may contain acetylene black. The conductive assistant may be composed of acetylene black alone. In the case where the negative electrode material in embodiment 1 contains acetylene black as a conductive auxiliary, the charge-discharge efficiency of the battery can be further improved.

The anode material in embodiment 1 may further contain a 2 nd solid electrolyte material.

With the above configuration, the charge/discharge efficiency and the discharge capacity of the battery can be further improved.

In addition, the reduction potential with respect to lithium of the 2 nd solid electrolyte material may be lower than the reduction potential with respect to lithium of the 1 st solid electrolyte material.

In the case where the reduction potential with respect to lithium of the 2 nd solid electrolyte material is lower than the reduction potential with respect to lithium of the 1 st solid electrolyte material, the 2 nd solid electrolyte material does not decompose when the halide reducing agent performs absorption and release of Li. Therefore, the negative electrode material in embodiment 1 can ensure good ion conductivity, and can improve the charge-discharge efficiency and discharge capacity of the battery.

The reduction potential of the solid electrolyte material with respect to lithium is measured, for example, by the following method.

First, an SUS foil, a solid electrolyte material, and a lithium foil are sequentially laminated in an insulating outer tube. The laminate was produced by pressure molding. Next, stainless steel current collectors were disposed above and below the stacked body, and current collecting leads were attached to the current collectors. Finally, the insulating outer tube was sealed with an insulating collar to block the outside atmosphere, thereby producing a cell for measuring reduction potential.

The obtained cell for measuring reduction potential was placed in a thermostatic bath at 25 ℃. The reduction potential with respect to lithium was determined by cyclic voltammetry measurements, using lithium as the reference potential, with potential sweeps from-0.5V to 6V at a rate of 5 mV/s.

As the 2 nd solid electrolyte material, for example, a sulfide solid electrolyte material and an oxide solid electrolyte material can be used.

As the sulfide solid electrolyte material, Li can be used₂S-P₂S₅、Li₂S-SiS₂、Li₂S-B₂S₃、Li₂S-GeS₂、Li_3.25Ge_0.25P_0.75S₄、Li₁₀GeP₂S₁₂And the like. Further, LiX (X: F, Cl, Br, I), Li may be added thereto₂O、MO_q、Li_pMO_q(M: at least one selected from P, Si, Ge, B, Al, Ga, In, Fe and Zn) (P, q: natural numbers), and the like.

As the oxide solid electrolyte material, for example, LiTi can be used₂(PO₄)₃NASICON-type solid electrolyte material (LaLi) TiO represented by substituted element thereof₃Perovskite type solid electrolyte material of system, Li₁₄ZnGe₄O₁₆、Li₄SiO₄、LiGeO₄And a LISICON-type solid electrolyte material represented by an element substitution body thereof, and Li₇La₃Zr₂O₁₂And garnet-type solid electrolyte materials typified by element substitutes thereof, and Li₃N and its H-substituted form, Li₃PO₄And N-substituted form thereof, and LiBO₂、Li₃BO₃Etc. based on Li-B-O compound with addition of Li₂SO₄、Li₂CO₃And glass, glass ceramic, and the like.

The 2 nd solid electrolyte material may also contain a sulfide solid electrolyte material. For example, the 2 nd solid electrolyte material may also contain Li₂S-P₂S₅。Li₂S-P₂S₅Is highly ion conductive and stable against reduction. Thus, by including Li₂S-P₂S₅The negative electrode material of embodiment 1 can further improve the charge/discharge efficiency and the discharge capacity of the battery.

The shape of the 2 nd solid electrolyte material is not particularly limited, and may be, for example, a needle shape, a spherical shape, an elliptical spherical shape, or the like. For example, the shape of the 2 nd solid electrolyte material may be a particle shape.

Fig. 2 is a cross-sectional view showing a schematic configuration of a negative electrode material 1000 that is an example of the negative electrode material in embodiment 1. In this example, the halide reducing agent is in the form of particles (for example, spheres), and the 2 nd solid electrolyte material is in the form of particles (for example, spheres).

The negative electrode material 1000 in embodiment 1 includes halide reduction particles 101, 2 nd solid electrolyte particles 102, and a conductive assistant 103.

For example, when the halide reducing particles 101 in embodiment 1 are in the form of particles (for example, spheres), the median particle diameter of the halide reducing particles 101 may be 0.1 μm or more and 100 μm or less. In the present specification, the median diameter of the particles means a particle diameter corresponding to 50% of the volume accumulation (d50) obtained from a particle size distribution measured on a volume basis by a laser diffraction scattering method.

When the median diameter of the halide reductant particles 101 is 0.1 μm or more, the halide reductant particles 101 and the 2 nd solid electrolyte particles 102 can be dispersed in the negative electrode material 1000 in a good state. This improves the charge/discharge characteristics of the battery. When the median diameter of the halide-reduced particles 101 is 100 μm or less, lithium diffusion in the halide-reduced particles 101 becomes fast. Therefore, the operation at high output of the battery becomes easy.

The halide reductant particles 101 may have a median particle size greater than the median particle size of the 2 nd solid electrolyte particles 102. This enables the halide reduced particles 101 and the 2 nd solid electrolyte particles 102 to be in a good dispersion state.

The median diameter of the 2 nd solid electrolyte particles 102 may be 100 μm or less. When the median diameter is 100 μm or less, the halide reduced particles 101 and the 2 nd solid electrolyte particles 102 can be formed in a good dispersion state in the negative electrode material. Therefore, the charge-discharge characteristics are improved.

The median diameter of the 2 nd solid electrolyte particles 102 may be 10 μm or less.

With the above configuration, the halide reducing particles 101 and the 2 nd solid electrolyte particles 102 can be dispersed in the negative electrode material in a good state.

The anode material 1000 in embodiment 1 may include a plurality of halide reductant particles 101 and a plurality of 2 nd solid electrolyte particles 102.

The content of the halide reducing particles 101 and the content of the 2 nd solid electrolyte particles 102 in the negative electrode material 1000 in embodiment 1 may be the same or different from each other.

The anode material in embodiment 1 may also contain materials other than the halide reducing agent, the conduction auxiliary agent, and the 2 nd solid electrolyte material. The negative electrode material in embodiment 1 may contain, for example, a negative electrode active material and a binder. As the binder, a material exemplified as a binder contained in at least one of the negative electrode, the electrolyte layer, and the positive electrode in embodiment 2 described later can be used.

The anode material in embodiment 1 may contain an anode active material having a characteristic of occluding and releasing metal ions (for example, lithium ions). As the negative electrode active material, for example, a metal material, a carbon material, an oxide, a nitride, a tin compound, a silicon compound, or the like can be used. The metallic material may be elemental metal. Alternatively, the metallic material may be an alloy. Examples of the metal material include lithium metal and a lithium alloy. Examples of the carbon material include natural graphite, coke, carbon for graphitization, carbon fiber, spherical carbon, artificial graphite, amorphous carbon, and the like.

The negative electrode material according to embodiment 1 may contain, for example, 30% by mass or more of a halide reducing agent, and may contain 80% by mass or more of a halide reducing agent. When the negative electrode material contains 30 mass% or more of the halide reducing agent, the energy density of the battery can be sufficiently ensured.

With the above configuration, the negative electrode material in embodiment 1 can improve the charge/discharge efficiency of the battery.

The negative electrode material in embodiment 1 may contain, for example, 20 mass% or less of the conductive auxiliary agent, and may contain 10 mass% or less of the conductive auxiliary agent. When the negative electrode material contains 20 mass% or less of the conductive auxiliary agent, the energy density of the battery can be sufficiently ensured.

With the above configuration, the negative electrode material in embodiment 1 can improve the charge/discharge efficiency of the battery.

The negative electrode material in embodiment 1 may contain, for example, 70 mass% or less of the 2 nd solid electrolyte material, and may contain 20 mass% or less of the 2 nd solid electrolyte material.

With the above configuration, the negative electrode material in embodiment 1 can improve the charge/discharge efficiency of the battery.

In the anode material in embodiment 1, with respect to the volume ratio "v: 100-v "(here, v represents the volume ratio of the halide reducing agent), 30. ltoreq. v.ltoreq.95 can be satisfied. When v is 30. ltoreq.v, a sufficient energy density of the battery can be ensured. In addition, in the case where v.ltoreq.95, the operation at high output becomes easy.

The negative electrode material in embodiment 1 can be produced, for example, by mixing a reducing agent of a halide solid electrolyte material produced in advance with a conductive auxiliary agent, and by mixing a reducing agent of a halide solid electrolyte material produced in advance with a conductive auxiliary agent and a 2 nd solid electrolyte material when a 2 nd solid electrolyte material is added. As another method, the negative electrode material in embodiment 1 can be produced, for example, by the following method: an electrochemical cell was prepared by mixing a halide solid electrolyte material, a conduction auxiliary agent, and a 2 nd solid electrolyte material, using the resulting mixture as a working electrode, and a Li-containing compound as a counter electrode, and the halide solid electrolyte material of the working electrode was reduced by sweeping a constant current in the cell.

(embodiment mode 2)

Embodiment 2 is explained below. The description overlapping with embodiment 1 described above is appropriately omitted.

Fig. 3 is a sectional view showing a schematic configuration of a battery in embodiment 2.

The battery 2000 in embodiment 2 includes a negative electrode 201, an electrolyte layer 202, and a positive electrode 203.

The negative electrode 201 includes the same negative electrode material 1000 as in embodiment 1 described above.

The electrolyte layer 202 is disposed between the negative electrode 201 and the positive electrode 203.

With the above configuration, the battery of embodiment 2 can improve charge and discharge efficiency.

The negative electrode 201 may be formed of only the negative electrode material 1000 in embodiment 1.

With the above configuration, the battery of embodiment 2 can further improve the charge/discharge efficiency of the battery.

The thickness of the negative electrode 201 may be 10 μm or more and 500 μm or less. By setting the thickness of the negative electrode to 10 μm or more, a sufficient energy density can be secured. Further, by setting the thickness of the negative electrode to 500 μm or less, the operation at high output is facilitated. That is, if the thickness of the negative electrode 201 is appropriately adjusted, the battery can be operated with high output while the energy density of the battery can be sufficiently ensured.

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

As the solid electrolyte material contained in the electrolyte layer 202, for example, a halide solid electrolyte material, a sulfide solid electrolyte material, an oxide solid electrolyte material, a polymer solid electrolyte material, or a complex hydride solid electrolyte material can be used.

As the halide solid electrolyte material, the same material as the halide solid electrolyte material before the reduction formation of the halide reducing agent contained in the negative electrode material in embodiment 1 may be used, or a different halide solid electrolyte material may be used.

As the sulfide solid electrolyte material, Li can be used₂S-P₂S₅、Li₂S-SiS₂、Li₂S-B₂S₃、Li₂S-GeS₂、Li_3.25Ge_0.25P_0.75S₄、Li₁₀GeP₂S₁₂And the like. Further, LiX (X: F, Cl, Br, I), Li may be added thereto₂O、MO_q、Li_pMO_q(M: is selected fromAt least one of P, Si, Ge, B, Al, Ga, In, Fe, and Zn) (P, q: natural number), etc.

As the polymer solid electrolyte material, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. By having an ethylene oxide structure, a large amount of lithium salt can be contained, and the ionic conductivity can be further improved. As the lithium salt, LiPF can be used₆、LiBF₄、LiSbF₆、LiAsF₆、LiSO₃CF₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)(SO₂C₄F₉)、LiC(SO₂CF₃)₃And the like. As the lithium salt, 1 lithium salt selected from among these lithium salts can be used alone. Alternatively, as the lithium salt, a mixture of two or more lithium salts selected from among these lithium salts can be used.

As the complex hydride solid electrolyte material, LiBH, for example, can be used₄-LiI、LiBH₄-P₂S₅And the like.

The electrolyte layer 202 may contain a solid electrolyte material as a main component. That is, the electrolyte layer 202 may contain 50% by mass or more (50% by mass or more) of the solid electrolyte material, for example, with respect to the entire electrolyte layer 202.

With the above configuration, the charge/discharge characteristics of the battery can be further improved.

The electrolyte layer 202 may contain, for example, 70% by mass or more (70% by mass or more) of a solid electrolyte material in a mass ratio to the entire electrolyte layer 202.

With the above configuration, the charge/discharge characteristics of the battery can be further improved.

The electrolyte layer 202 may contain a solid electrolyte material as a main component, and may also contain unavoidable impurities, starting materials used in synthesizing the solid electrolyte material, by-products, decomposition products, and the like.

The electrolyte layer 202 may contain 100% (100 mass%) of a solid electrolyte material in a mass ratio to the entire electrolyte layer 202, excluding, for example, impurities that cannot be mixed in an unavoidable manner.

With the above configuration, the charge/discharge characteristics of the battery can be further improved.

As described above, the electrolyte layer 202 may be formed only of the solid electrolyte material.

The electrolyte layer 202 may contain two or more of the materials listed as the solid electrolyte material. For example, the electrolyte layer 202 may contain a halide solid electrolyte material and a sulfide solid electrolyte material.

The thickness of the electrolyte layer 202 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 202 is 1 μm or more, the possibility of short-circuiting the negative electrode 201 and the positive electrode 203 is low. In addition, when the thickness of the electrolyte layer 202 is 300 μm or less, the operation at high output becomes easy. That is, if the thickness of the electrolyte layer 202 is appropriately adjusted, the battery can be operated with high output while sufficient safety of the battery can be ensured.

The positive electrode 203 includes positive electrode active material particles and solid electrolyte particles.

The positive electrode 203 contains a positive electrode active material having a characteristic of occluding and releasing metal ions (for example, lithium ions). As the positive electrode active material, a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion material, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxysulfide, a transition metal oxynitride, or the like can be used. In particular, when a lithium-containing transition metal oxide is used as the positive electrode active material, the production cost can be reduced, and the average discharge voltage can be increased. Examples of the lithium-containing transition metal oxide include Li (NiCoAl) O₂、Li(NiCoMn)O ₂、LiCoO ₂And the like.

The positive electrode 203 may contain a solid electrolyte material. As the solid electrolyte material, a solid electrolyte material exemplified as a material constituting the electrolyte layer 202 can be used. With the above configuration, the lithium ion conductivity in the positive electrode 203 is increased, and operation at high output is possible.

The median diameter of the positive electrode active material particles may be 0.1 μm or more and 100 μm or less. If the median diameter of the positive electrode active material particles is 0.1 μm or more, the positive electrode active material particles and the solid electrolyte material can be formed in a good dispersion state in the positive electrode. This improves the charge/discharge characteristics of the battery. When the median diameter of the positive electrode active material particles is 100 μm or less, lithium diffusion in the positive electrode active material particles becomes rapid. Therefore, the operation at high output of the battery becomes easy. That is, if the positive electrode active material particles have an appropriate size, a battery having excellent charge and discharge characteristics and capable of operating at high output can be obtained.

The median particle diameter of the positive electrode active material particles may be larger than the median particle diameter of the solid electrolyte material. This makes it possible to form a good dispersion state of the positive electrode active material particles and the solid electrolyte material.

Regarding the volume ratio "v" of the positive electrode active material particles and the solid electrolyte material contained in the positive electrode 203: 100-v "(here, v represents the volume ratio of the positive electrode active material particles), and 30. ltoreq. v.ltoreq.95. When 30. ltoreq. v, a sufficient energy density of the battery can be ensured. In addition, when v.ltoreq.95, the operation at high output of the battery becomes easy.

The thickness of the positive electrode 203 may be 10 μm or more and 500 μm or less. When the thickness of the positive electrode is 10 μm or more, a sufficient energy density of the battery can be ensured. In addition, when the thickness of the positive electrode is 500 μm or less, the operation of the battery at high output can be realized. That is, if the thickness of the positive electrode 203 is adjusted to an appropriate range, the energy density of the battery can be sufficiently ensured, and the battery can be operated with high output.

A binder may be contained in at least one of the anode 201, the electrolyte layer 202, and the cathode 203. The adhesive can improve the adhesion between the particles. The binder can improve the adhesiveness of the material constituting the electrode. Examples of the binder include: polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexamethyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexamethyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether sulfone, hexafluoropropylene, styrene-butadiene rubber, carboxymethyl cellulose, and the like. As the binder, a copolymer of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene can be used. Two or more materials selected from these materials may be mixed and used as the binder.

At least one of the anode 201 and the cathode 203 may include a conductive aid. The electron conductivity can be improved by the conductive assistant. Examples of the conductive aid include graphite such as natural graphite or artificial graphite, carbon black such as acetylene black or ketjen black, conductive fibers such as carbon fibers or metal fibers, fluorocarbons, metal powders such as aluminum, conductive whiskers such as zinc oxide or potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene. When the carbon conductive additive is used, cost reduction can be achieved.

The battery in embodiment 2 can be configured as a battery having various shapes such as a coin-type, cylindrical, angular (rectangular), sheet-type, button-type, flat-type, and laminated battery.

The operating temperature of the battery is not particularly limited, and may be-50 ℃ to 100 ℃. The higher the temperature, the higher the ionic conductivity of the halide reducing agent, and the higher the output operation.

The battery in embodiment 2 can be manufactured, for example, by preparing a material for forming a positive electrode, a material for forming an electrolyte layer, and a material for forming a negative electrode, respectively, and preparing a laminate in which the positive electrode, the electrolyte layer, and the negative electrode are arranged in this order by a known method.

As another manufacturing method, for example, the following method can be used.

First, a laminate in which a positive electrode, an electrolyte layer, and a negative electrode precursor layer containing a halide solid electrolyte material in a state before reduction formation of a halide reducing agent contained in the negative electrode material in embodiment 1 are arranged in this order is prepared.

Subsequently, a constant current is applied to the laminate. In this case, the positive electrode functions as a counter electrode, the negative electrode precursor layer functions as a working electrode, and the halide solid electrolyte material in the negative electrode precursor layer is reduced. Thus, the battery of embodiment 2 including the positive electrode, the electrolyte layer, and the negative electrode containing the halide reducing agent and the conductive auxiliary agent can be obtained.

That is, an example of the method for manufacturing a battery according to embodiment 2 includes the steps of:

preparing a laminate in which a positive electrode, an electrolyte layer, and a negative electrode precursor layer are arranged in this order, the negative electrode precursor layer containing a conductive auxiliary agent and a halide solid electrolyte material in a state before reduction formation of a halide reducing agent contained in the negative electrode material in embodiment 1; and

applying a current to the laminate.

(examples)

The details of the present disclosure will be described below using examples and comparative examples. The negative electrode material and the battery of the present disclosure are not limited to the following examples.

< example 1 >

[ production of the solid electrolyte Material ]

In an argon glove box with dew point below-60 ℃ with LiCl: YCl₃2.7: 1.1 molar ratio LiCl and YCl as raw material powders were weighed₃. Thereafter, these raw material powders were mixed, and the resulting mixture was subjected to a milling treatment at 600rpm for 25 hours using a planetary ball mill (model P-5 manufactured by フリッチュ). Through the above steps, the 1 st solid electrolyte material Li was obtained_2.7Y_1.1Cl₆(i.e., LYC).