JP2014102911A - Electrode material for all-solid battery, method of manufacturing the same and all-solid battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode material having high volume energy density, and Li ionic conductivity.SOLUTION: Disclosed is an electrode material for an all-solid battery containing a solid electrolyte and an active material, and the active material is a spherical particle-shaped active material having an average aspect ratio which is 1 or more and less than 1.15.

Description

  The present invention relates to an electrode material for an all-solid battery, a method for producing the same, and an all-solid battery using the same.

An all-solid battery in which the electrolyte is a solid electrolyte does not use a flammable organic solvent in the battery, and thus it is considered that the safety device can be simplified and that the manufacturing cost and productivity are excellent. In particular, in recent years, as the demand for hybrid vehicles and the like increases, it is demanded that an all-solid-state secondary battery has a higher energy density and output density and a smaller size.
In the field of such all-solid-state batteries, it has been reported that an oxide type electrode material is manufactured by a sintering method or the like. The sintering method is advantageous in terms of manufacturing cost because many products can be manufactured at the same time, but since the sintering process is performed at a high temperature, there is a concern that the reaction between the active material and other electrode components may occur. Is done. It is also desirable to increase the sintering density in order to increase the volume energy density of the electrode. In order to prevent the reaction between the active material and the solid electrolyte due to firing at a high temperature and to increase the density of the electrode after firing, the solid electrolyte that softens at a relatively low temperature (for example, Li _1.5 Al _{0. 5} Ge _0.5 (PO ₄ ) ₃ (hereinafter referred to as “LAGP”) is mixed with the active material, followed by firing (press firing) under a pressure of 100 kg / cm ² or more to form a positive electrode and a negative electrode. To do so was proposed in Patent Document 1. The press firing method proposed in Patent Document 1 is an effective method for obtaining a dense electrode. However, in order to produce a relatively large size battery (for example, a vehicle-mounted battery), the press firing method is used. Is necessary for mass production of batteries because it requires complicated equipment and increases costs. Therefore, in this technical field, it has been desired to produce an electrode having an improved volume energy density without the need for press firing.
Furthermore, in order to improve the volumetric energy density of the electrode, it is important to increase the ratio of the active material in the electrode material, but in the oxide type electrode material manufactured by the sintering method, the ratio of the active material is increased. Along with this, the binding of active material particles by the solid electrolyte and the lithium (Li) ion conduction path are reduced, and it is difficult to achieve a balance between volume energy density and Li ion conductivity.

JP 2010-225390 A

  In view of the above problems, an object of the present invention is to provide an electrode material having high volume energy density and Li ion conductivity.

  As a result of intensive studies on the above problems, the present inventor has sintered a mixture of a solid electrolyte and a spherical particulate active material having a specific average aspect ratio of 1 to less than 1.15 at a temperature equal to or higher than the softening point of the solid electrolyte. It has been found that a dense electrode material having a high relative density (or “sintered density”) with few voids can be obtained without performing press firing. Since the electrode material of the present invention is dense with few voids, the filling rate of the active material is high, and as a result, it has a high energy density. Furthermore, since the electrode material of the present invention is dense with few voids, it has high Li ion conductivity. When the active material particles having an average aspect ratio exceeding the specific range are used when the active material is a spherical particle active material having an average aspect ratio within the specific range as described above. Compared to, a dense electrode material having a high relative density can be obtained. The reason why a dense electrode material having a high relative density is obtained is that when a spherical particle-shaped active material having a specific average aspect ratio of 1 or more and less than 1.15 is used, When the solid electrolyte is softened by sintering the mixture with the solid electrolyte at a temperature equal to or higher than the softening point of the solid electrolyte, there is less friction and catching between the active material particles, and the softened solid electrolyte is activated by the capillary action. It is considered that the active material particles easily rearrange spontaneously by penetrating in between. Simultaneously with the rearrangement of the active material particles, the surface tension of the softened solid electrolyte becomes a driving force, causing the active material particles and the softened solid electrolyte to aggregate, resulting in voids in the mixture of the active material and the solid electrolyte. It is considered that a dense electrode material having a high relative density (or “sintered density”) is obtained.

  That is, according to one aspect of the present invention, an electrode material for an all-solid battery containing a solid electrolyte and a spherical particulate active material, wherein the active material has a spherical particulate shape having an average aspect ratio of 1 or more and less than 1.15. An electrode material for an all-solid battery that is an active material is provided.

  According to another aspect of the present invention, the all solid state battery includes a positive electrode, a negative electrode, and a solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode or the negative electrode is formed on a current collector and one surface thereof. Each of the positive electrode and the negative electrode is formed on the current collector and one side thereof on the condition that the electrode material layer is included or the positive electrode active material exhibits a potential nobler than the redox potential of the negative electrode active material. An all-solid-state battery including a layer made of the electrode material for all-solid-state batteries is provided.

According to yet another aspect of the invention,
(A) a step of mixing a solid electrolyte and a spherical particle-shaped active material having an average aspect ratio of 1 or more and less than 1.15;
(B) a step of press-molding the mixture obtained from step (a) to form a preform, and (c) the preform formed in step (b) of the solid electrolyte in an inert gas atmosphere. Sintering at a temperature above the softening point;
The manufacturing method of the electrode material for all-solid-state batteries containing is provided.

  The electrode material for an all-solid-state battery of the present invention includes a solid electrolyte and a spherical particulate active material having an average aspect ratio of 1 or more and less than 1.15 as an active material, thereby realizing a high sintering density. As a result, high volume energy density and high conductivity can be achieved.

FIG. 1 is a graph showing the relative density (%) of the pellet-shaped sintered bodies of Comparative Examples 1 and 2. FIGS. 2A and 2B show scanning electron microscope (SEM) photographs of the pellet-like sintered bodies of Comparative Examples 1 and 2, respectively. 3A to 3E show SEM photographs of the active materials used in Comparative Example 3, Example 1, and Comparative Examples 4 to 6, respectively. FIG. 4 shows a graph in which the average aspect ratio of the active material particles is plotted on the horizontal axis and the relative density (%) of the sintered body is plotted on the vertical axis. FIG. 5 shows the relative density (%) of the preform before sintering of Comparative Example 3 and Example 1 and the relative density (%) of the sintered body (electrode material) obtained by sintering the preform. The graph for comparing is shown. 6A and 6B show SEM photographs of the sintered bodies of Comparative Example 3 and Example 1, respectively. FIG. 7 shows a graph in which active material / (active material + solid electrolyte) is plotted on the horizontal axis and Li ion conductivity (S / cm) is plotted on the vertical axis for the electrode material. FIGS. 8A and 8B show an electrode material having an active material / (active material + solid electrolyte) of 0.70 and an electrode material having an active material / (active material + solid electrolyte) of 0.75, respectively. The SEM photograph of is shown.

Examples of the solid electrolyte that can be used for the electrode material for an all-solid battery of the present invention include a glassy solid electrolyte that softens at the firing temperature, for example, LiPO ₄ , Li ₂ SiO ₂ , Li ₂ SiO ₄ , Li _{1 + x} Al _x Ti _{2. -x (PO 4) 3 (0} ≦ x ≦ 2), Li 1 + x Al x Ge 2-x (PO 4) 3 (0 ≦ x ≦ 2), Li 2 O-B 2 O 3, Li 2 O-Al _{2 O 3, LiTaO 3, Li} 2 S-P 2 S 5, Li is _{2 I-Li 2 S-P} 2 S 5 and the like. As the solid electrolyte, Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ (0 ≦ x ≦ 2), particularly from the viewpoint of conductivity, from the viewpoint of having high conductivity and a stable reduction potential, Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ (hereinafter referred to as “LAGP”) is preferable. In particular, LAGP has a crystallization temperature of 590 ° C., and it is known that the lithium ion conductivity is improved when crystallized. Also, since the softening point is 540 ° C., it is compared with the conventional sintering method. It is possible to produce electrodes at sintering temperatures as low as 600 ° C.

Examples of the active material in the form of spherical particles that can be used for the electrode material for an all-solid battery of the present invention include Nb ₂ O ₅ , WO ₂ , TiO ₂ , Li ₄ Ti when the active material is used as a negative electrode active material. ₅ O ₁₂ , or one or a combination of two or more thereof may be mentioned. Furthermore, as an example of the active material in the form of spherical particles that can be used for the electrode material for an all solid state battery of the present invention, when the active material is used as a positive electrode active material, LiCoO ₂ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNiPO ₄ , LiMnPO ₄ , LiNiO ₂ , LiMnO ₂ , LiCoMnO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , or one or a combination of two or more thereof can be given. As the spherical particle-like active material, Nb ₂ O ₅ , TiO ₂ , and WO ₂ are preferable, and Nb ₂ O ₅ is more preferable in that it does not react with LAGP at the heat treatment temperature.

The spherical particulate active material has an average aspect ratio of 1 or more and less than 1.15. In this specification, the average aspect ratio is the ratio of the major axis (DL) to the minor axis (DS) of a particle image measured using a scale by selecting 100 arbitrary particles from a photographic image of an electron microscope (DL / DS) is defined as the average value. The active material in the form of spherical particles having such an average aspect ratio is, for example, an active material powder (for example, Nb ₂ O ₅ powder) air-flowed with a carrier gas (for example, O ₂ gas), and separately supplied fuel with an oxygen burner. It can be produced by passing through a high-temperature flame generated by combustion to melt the powder particles and spheroidizing by the surface tension of the melt.

  In the electrode material for an all-solid-state battery of the present invention, the higher the volume fraction of the spherical active material particles, the higher the volume energy density, but in order to ensure a practically desirable conductivity, preferably a solid electrolyte and The volume percentage of the total volume of the spherical particle active material to be the total volume of the spherical particle active material is 70% by volume or less, that is, (total volume of the spherical active material particles) / [(of the spherical active material particles The spherical active material particles are preferably present in the electrode material in such an amount that the total volume) + (total volume of the solid electrolyte)] is 0.7 or less. The volume ratio of the spherical particulate active material to the solid electrolyte is more preferably 70:30 to 30:70, and most preferably 70:30 to 50:50. The ratio between the active material in the form of spherical particles and the solid electrolyte can be determined by a known method such as ICP (inductively coupled plasma) emission spectroscopy, and the void ratio can be determined by a known method such as mercury intrusion. It can ask for. The all-solid-state battery electrode material of the present invention preferably has a relative density of 87% or more.

  The electrode material of the present invention may be an optional component known in the art as a solid material for an electrode for an all solid state battery, for example, a conductive additive (for example, carbon black, carbon fiber, etc.), a binder, if necessary. (Binder) may be included. However, as described above, since the electrode material of the present invention can achieve high conductivity by the combination of the solid electrolyte and the spherical active material particles, when the electrode material of the present invention contains a conductive additive, The amount of conductive aid is preferably less, and in order to achieve a higher volumetric energy density, it is preferred not to include a conductive aid. Further, in the electrode material of the present invention, since the solid electrolyte can act as a binder for the active material in the form of spherical particles as described above, no binder is included to achieve high conductivity. It is preferable.

The electrode material of the present invention is
(A) a step of mixing a solid electrolyte and a spherical particle-shaped active material having an average aspect ratio of 1 or more and less than 1.15 (and optional components if necessary);
(B) a step of press-molding the mixture obtained from step (a) to form a preform, and (c) the preform formed in step (b) of the solid electrolyte in an inert gas atmosphere. Sintering at a temperature above the softening point;
It can manufacture by the method containing.

  By using a spherical particle-shaped active material having an average aspect ratio of 1 or more and less than 1.15, the molding density of a preform (before sintering) obtained by mixing the active material with a solid electrolyte and press-molding is reduced. Can be improved. Further, by sintering the preform obtained by press molding at a temperature equal to or higher than the softening point of the solid electrolyte in an inert gas atmosphere, the softened solid electrolyte is intercalated between the active material particles by capillary action as described above. It is thought that the active material particles easily rearrange spontaneously by penetrating into. Simultaneously with the rearrangement of the active material particles, the surface tension of the softened solid electrolyte becomes the driving force, causing the active material particles and the softened solid electrolyte to agglomerate. It is considered that the shrinkage of the body occurs, and as a result, the voids existing in the preform can be reduced, and a denser, that is, sintered body (electrode material) having a higher relative density can be obtained. It is done.

  In the step (a), a powdered solid electrolyte and a spherical particle-shaped active material having an average aspect ratio of 1 or more and less than 1.15 are expressed by (total volume of spherical active material particles) / [(spherical active material). The mixing can be performed, for example, at room temperature in such a ratio that the total volume of the substance particles) + (the total volume of the solid electrolyte)] is 0.7 or less. Mixing can be performed, for example, by mortar mixing or ball mill mixing.

The step (b) is a step in which the mixture obtained from the step (a) is press-molded to form a preformed body having a shape such as a pellet or a film. Press molding can be performed by a known method. In press molding, for example, the mixture obtained from step (a) is filled in a mold, and using a pressing device such as a uniaxial press, a cold isostatic pressing (CIP) device, or a hot press, for example, The pressing can be performed at a temperature of about room temperature (20 ° C.) to about 150 ° C. and a pressure of about 0.2 to about 20 ton / cm ² for about 3 seconds to about 30 minutes.

In the step (c), the preform formed in the step (b) is heated to a temperature equal to or higher than the softening point of the solid electrolyte in an inert gas (eg, argon gas) atmosphere (however, the solid electrolyte and the active material). And a temperature lower than the decomposition temperature). The obtained sintered body is allowed to cool to room temperature.
The electrode material of the present invention achieves high volume energy density and high Li ion conductivity without press firing, but press firing is performed in order to obtain a denser or higher relative density electrode material. It is not excluded.

  An electrode (a negative electrode or a positive electrode, or both a negative electrode and a positive electrode) can be obtained by forming a current collector on one surface of the electrode material formed in the step (c) by a method known in the art. it can. For example, a film-like or foil-like current collector material (for example, copper, aluminum, gold) is applied to one side of the electrode material formed in the step (c), or the current collector material is used in the step (c). An electrode can be obtained by vapor-depositing on one side of the electrode material formed in (1).

  The electrode material of the present invention may be used as a negative electrode material or a positive electrode material. Therefore, the all-solid-state battery which a negative electrode material or a positive electrode material consists of the electrode material of this invention can be comprised. Moreover, all the solid-state batteries which both a negative electrode material and a positive electrode material consist of the electrode material of this invention can also be comprised. That is, an all-solid battery can be constructed using the electrode material of the present invention for at least one of a negative electrode material and a positive electrode material. However, in the case where both the negative electrode material and the positive electrode material constitute an all-solid battery comprising the electrode material of the present invention, the positive electrode active material is required to exhibit a potential nobler than the redox potential of the negative electrode active material. . Furthermore, when both the negative electrode material and the positive electrode material constitute an all-solid battery comprising the electrode material of the present invention, the negative electrode material and the positive electrode material each independently have an active material in the form of spherical particles of 1 or more and 1.15. The condition of having an average aspect ratio of less than is satisfied.

The solid electrolyte disposed between the positive electrode and the negative electrode is not particularly limited as long as it is made of a material that can function as a solid electrolyte. As the solid electrolyte, those similar to those generally used in all solid state batteries can be used. Examples of solid electrolytes include, for example, sulfide-based solid electrolytes (eg, Li ₂ S—P ₂ S ₅ , Li ₂ I—Li ₂ S—P ₂ S ₅ ), oxide-based solid electrolytes (eg, LiPO ₄ , Li ₂ SiO ₂ , Li ₂ SiO ₄ , Li _1.5 Al _0.5 Ti _1.5 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ , Li ₂ O—B ₂ O ₃ , Li ₂ O—Al ₂ O ₃ ) and the like. The solid electrolyte is disposed between the negative electrode and the positive electrode in any size and shape depending on the intended use of the all-solid battery, and the type and shape of the solid electrolyte are not particularly limited, and depend on the use of the all-solid battery. It can be selected appropriately.

  The all solid state battery obtained by using the electrode material of the present invention can have a positive electrode terminal and a negative electrode terminal connected to the positive electrode current collector and the negative electrode current collector in addition to the above-described members. The types and shapes of these members can be appropriately selected according to the use of the all solid state battery.

  The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited by these Examples.

Comparative Example 1: Press firing of solid electrolyte (LAGP) pellets 0.3 g of solid electrolyte Li _1.5 Al _0.5 Ge _0.5 (PO ₄ ) ₃ (LAGP) powder (Hosokawa Micron Corporation) under an argon gas atmosphere Obtained, and filled in a carbon die (inner diameter 10 mm) and heated by a hot press machine at 600 ° C. under a pressure of 0.5 ton / cm ² for 0.5 hour under an argon gas atmosphere. A shaped sintered body was obtained.

Comparative Example 2: Solid electrolyte (LAGP) single pellet firing (no press load)
In an argon gas atmosphere, 0.3 g of LAGP powder (obtained from Hosokawa Micron Co., Ltd., average particle size 200 nm) is filled in a die (inner diameter 10 mm) and pressed at a pressure of 1.5 ton / cm ² for 1 minute. A pellet-like molded body was obtained. Next, the pellet-shaped formed body was taken out of the die and fired at 600 ° C. for 2 hours in an argon gas atmosphere by an atmosphere control furnace to obtain a pellet-shaped sintered body.

About the pellet-shaped sintered compact obtained in Comparative Examples 1 and 2, the relative density (or sintered density) (%) was 65% and 84%, respectively. About the pellet-shaped sintered compact obtained by the comparative examples 1 and 2, the scanning electron microscope (SEM) photograph was image | photographed (JSMOL JSM-6610LA was used, and so on). The relative density results are shown in FIG. 1, and SEM photographs of Comparative Examples 1 and 2 are shown in FIGS. 2 (a) and 2 (b), respectively.
For Comparative Examples 1 and 2, the relative density (%) was determined by the following formula.
Relative density (%) = 100 × bulk density of sintered body (g / cm ³ ) / true density of solid electrolyte (g / cm ³ )
As shown in FIG. 1, the pellet-like sintered body of Comparative Example 1 obtained using a hot press machine, contrary to expectation, was sintered by Comparative Example 2 formed by firing without a press load. The relative density is much lower than the body.
From the SEM photographs of FIGS. 2 (a) and (b), the pellet-like sintered body of Comparative Example 1 was not subjected to the observation of the melt structure of the solid electrolyte, despite being press-fired by a hot press machine. It was confirmed to have a structure with many voids. When the pellet-like sintered body of Comparative Example 1 was further examined with an infrared absorption carbon sulfur analyzer, carbon was detected. The pellet-like sintered body of Comparative Example 1 is considered to be densified by carbon. It became clear that hot pressing is not an effective densification means for LAGP, which is a promising electrolyte as an oxide solid electrolyte.

Example 1 and Comparative Examples 3-6
Niobium pentoxide (Nb ₂ O ₅ ) powder (hereinafter referred to as “raw powder”) (average aspect ratio 2.14) obtained from Mitsui Kinzoku Co., Ltd. is air-flowed with a carrier gas (O ₂ gas) and supplied separately. The resulting fuel is passed through a high-temperature flame generated by burning with an oxygen burner to melt the powder particles, and spheroidized by the surface tension of the melt, to form spherical particles of Nb ₂ O ₅ (average aspect ratio 1.08) ( Hereinafter also referred to as “spherical powder”.
Since niobium pentoxide (Nb ₂ O ₅ ) has the property of being columnarized by heat treatment, an average aspect ratio of 1 is obtained by heat-treating the spherical particle-shaped Nb ₂ O ₅ (spherical powder) at 1000 ° C. for 2 hours. .15 Nb ₂ O ₅ particles (hereinafter referred to as “1000 ° C. calcined powder”), and the spherical particles of Nb ₂ O ₅ (spherical powder) are heat-treated at 1100 ° C. for 2 hours to obtain an average aspect ratio. An average aspect ratio is obtained by obtaining Nb ₂ O ₅ particles (hereinafter referred to as “1100 ° C. calcined powder”) of 1.21, and heat treating the spherical Nb ₂ O ₅ (spherical powder) at 1200 ° C. for 2 hours. Nb ₂ O ₅ particles (hereinafter referred to as “1200 ° C. calcined powder”) having an A of 1.28.
The average aspect ratio of these Nb ₂ O ₅ particles was determined by selecting 100 arbitrary particles from a photographic image of an electron microscope and measuring the major axis (DL) and minor axis (DS) of the particle image using a scale. And it calculated | required by calculating the average value of ratio (DL / DS). The SEM photograph of said raw material powder, spherical powder, 1000 degreeC calcined powder, 1100 degreeC calcined powder, and 1200 degreeC calcined powder is shown to Fig.3 (a)-(e).

The above raw material powder was mixed with a solid electrolyte (LAGP) at a volume ratio of 50:50 in an argon gas atmosphere at room temperature using a mortar, and the resulting mixture was then made into a press molding machine (manufactured by Sansho Industry Co., Ltd.). Using a Newton press machine, press molding (uniaxial molding) was performed at a pressure of 1.5 ton / cm ² to form a pellet-shaped preform. The relative density of the pellet-shaped preform was 58%. The obtained preform was sintered for 2 hours at 600 ° C. under an argon gas atmosphere in an atmosphere control furnace and allowed to cool to room temperature. The relative density of the obtained sintered body was 59.3% (Comparative Example 3).
A pellet-shaped preform was formed in the same manner as in Comparative Example 3 except that the raw material powder was replaced with a spherical powder. The relative density of this preform was 65.2%. The obtained pellet-shaped preform was sintered in an atmosphere control furnace for 2 hours under an argon gas atmosphere, and the obtained sintered body was allowed to cool to room temperature. The relative density of the obtained sintered body was 87.7% (Example 1).
A sintered body (electrode material) was obtained in the same manner as in Comparative Example 3 except that the raw material powder was replaced with calcined powder at 1000 ° C., and then the relative density of the sintered body was determined. The relative density of the sintered body was 67% (Comparative Example 4).
After obtaining a sintered body (electrode material) in the same manner as in Comparative Example 3 except that the raw material powder was replaced with calcined powder at 1100 ° C., the relative density of the sintered body was determined. The relative density of the sintered body was 65% (Comparative Example 5).
A sintered body (electrode material) was obtained in the same manner as in Comparative Example 3 except that the raw material powder was replaced with 1200 ° C. calcined powder, and then the relative density of the sintered body was determined. The relative density of the sintered body was 65% (Comparative Example 6).
FIG. 4 shows a graph in which the average aspect ratio obtained for each sintered body is plotted on the horizontal axis and the relative density (%) of the sintered body is plotted on the vertical axis. Furthermore, the graph which compares the relative density (%) of the preformed body (before sintering) of Comparative Example 3 and Example 1 and the sintered body (electrode material) obtained after sintering is shown in FIG.
In addition, about Example 1 and Comparative Examples 3-6, the relative density (%) was calculated | required by the following formula.
Relative density (%) = 100 × d ₀ / {(m ₁ + m ₂ ) / (m ₁ / d ₁ + m ₂ / d ₂ )}
In the above formula, d ₀ is the bulk density (g / cm ³ ) of the sintered body, d ₁ is the true density of the solid electrolyte (g / cm ³ ), and d ₂ is the true density of the active material (g / cm ³ ). cm ³ ), m ₁ is the mass (g) of the solid electrolyte, and m ₂ is the mass (g) of the active material.

  From FIG. 4, it can be seen that when the average aspect ratio is less than 1.15, the relative density increases rapidly. 5 that the relative density of the preformed body of Example 1 and the sintered body obtained after sintering is considerably higher than that of Comparative Example 3.

<Measurement of Li ion conductivity>
About the sintered compact of said Example 1 and Comparative Example 3, Li ion conductivity was calculated | required by the alternating current impedance method in the range of 10 mV alternating current voltage and 1 MHz-0.1 MHz at the temperature of 25 degreeC. The Li ion conductivity of Comparative Example 3 was 3.3 × 10 ⁻⁶ S / cm, whereas the Li ion conductivity of Example 1 was 1.3 × 10 ⁻⁵ S / cm. 1 surprisingly showed a Li ion conductivity about 4 times that of Comparative Example 3.

  6A and 6B show SEM photographs of the sintered bodies of Comparative Example 3 and Example 1, respectively. 6 (a) and 6 (b), it can be seen that the sintered body of Example 1 has fewer voids and is denser than the sintered body of Comparative Example 3. Further, from the SEM photograph of the sintered body of Comparative Example 3 (FIG. 6A), it is recognized that there are continuous voids in a network form, whereas the SEM photograph of the sintered body of Example 1 (Figure From 6 (b), no network-like continuous voids as observed in Comparative Example 3 are observed. When network-like continuous voids are present in the electrode material, the Li ion conduction path becomes long, resulting in low Li ion conductivity. The sintered body of Example 1 is considered to exhibit high Li ion conductivity because the solid electrolyte forming the Li ion conduction path is closely packed between the active material particles.

  Next, the solid electrolyte (LAGP) and the active material in the form of spherical particles (“spherical powder”) used in Example 1 were mixed at the blending ratio shown in Table 1 below, and the sintered body was the same as in Comparative Example 3 above. After obtaining (electrode material), about the obtained sintered compact (electrode materials 1-7), Li ion conductivity is measured by the alternating current impedance method in the range of AC voltage of 10mV at the temperature of 25 degreeC, and 1MHz-0.1MHz. Asked. The electrode material 2 is the sintered body of Example 1.

  About the obtained electrode materials 1-7, the graph which plotted the active material / (active material + solid electrolyte) on the horizontal axis | shaft and Li ion conductivity on the vertical axis | shaft is shown in FIG.

From FIG. 7, it can be seen that when the active material / (active material + solid electrolyte) exceeds 0.70 (indicated by a bold dotted line in FIG. 7), the Li ion conductivity rapidly decreases.
Electrode material 4 [active material / (active material + solid electrolyte) = 0.70] and electrode material 5 [active material / (active material + solid electrolyte) = 0.75 shown in FIGS. 8 (a) and 8 (b), respectively. ], The active material / (active material + solid electrolyte) exceeds 0.70, and there are many continuous voids in the electrode material. When the lithium ion conduction path becomes longer due to the continuous air gap, the Li ion conductivity decreases. The decrease in the Li ion conductivity when the active material / (active material + solid electrolyte) exceeds 0.70 is considered to be due to the decrease in the Li ion conduction path.

Claims (7)

  An electrode material for an all solid state battery comprising a solid electrolyte and an active material, wherein the active material is an active material in the form of spherical particles having an average aspect ratio of 1 or more and less than 1.15.   The electrode material for all-solid-state batteries according to claim 1, wherein the solid electrolyte is an oxide solid electrolyte.   The electrode material for an all-solid-state battery according to claim 1 or 2, wherein the volume percentage of the spherical particulate active material with respect to the total volume of the solid electrolyte and the spherical particulate active material is 70 volume% or less. The oxide solid electrolyte is _{Li 1 + x Al x Ge 2} -x (PO 4) 3 (0 ≦ x ≦ 2), all solid state battery electrode material according to claim 2.   The electrode material for an all-solid-state battery according to any one of claims 1 to 4, wherein the spherical particulate active material is niobium pentoxide.   The positive electrode, the negative electrode, and a solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode or the negative electrode is formed on a current collector and one surface thereof. Each of the positive electrode and the negative electrode on the one side of the current collector on the condition that the positive electrode active material exhibits a potential nobler than the redox potential of the negative electrode active material. The all-solid-state battery containing the layer which consists of the electrode material for all-solid-state batteries as described in any one of Claims 1-5 formed in this. (A) a step of mixing a solid electrolyte and a spherical particle-shaped active material having an average aspect ratio of 1 or more and less than 1.15;
(B) a step of pressing the mixture obtained from step (a) to form a preform, and (c) the solid electrolyte formed in step (b) under an inert gas atmosphere. Sintering at a temperature equal to or higher than the softening point of
The manufacturing method of the electrode material for all-solid-state batteries containing.