JP6248498B2 - All-solid battery and method for manufacturing the same - Google Patents

Description

  The present invention relates to an all-solid battery and a method for manufacturing the same.

  In recent years, the demand for batteries as a power source for portable electronic devices such as mobile phones and portable personal computers has greatly increased. In a battery used for such an application, an electrolyte (electrolytic solution) such as an organic solvent has been conventionally used as a medium for moving ions.

  However, in the battery having the above configuration, there is a risk that the electrolyte solution leaks. Moreover, the organic solvent etc. which are used for electrolyte solution are combustible substances. For this reason, it is required to further increase the safety of the battery.

  Therefore, as one countermeasure for enhancing the safety of the battery, it has been proposed to use a solid electrolyte as the electrolyte instead of the electrolytic solution. Furthermore, development of an all-solid battery in which a solid electrolyte is used as an electrolyte and the other constituent elements are also made of solid is being promoted.

  For example, Japanese Patent Laid-Open No. 2007-5279 (hereinafter referred to as Patent Document 1) discloses an all-solid-state battery manufacturing method in which an active material containing a phosphoric acid compound and a solid electrolyte are mixed with a solution containing a binder and a plasticizer, respectively. The active material green sheet and the solid electrolyte green sheet obtained by forming the slurry by dispersing in the slurry are laminated, and the binder and the plasticizer are thermally decomposed and removed, followed by firing. Thus, it is described that a laminate of an all-solid battery is manufactured.

JP 2007-5279 A

  In the laminate of an all-solid battery obtained by firing as described in Patent Document 1, since the resin such as the binder and the plasticizer is not sufficiently removed, carbon or carbide as a resin residue Remains inside the solid electrolyte layer.

  Moreover, since the solid electrolyte material that is the main component of the solid electrolyte layer has a smaller action of decomposing or burning the resin than the electrode active material and the conductive material, among the layers constituting the laminate of the all-solid battery, The solid electrolyte layer is the layer where the resin is most difficult to remove.

  Therefore, electronic conductivity is generated in the solid electrolyte layer due to the resin residue, which may cause an internal short circuit between the positive electrode layer and the negative electrode layer via the solid electrolyte layer. Further, there is a problem that the charge / discharge characteristics of the all-solid battery are deteriorated by the resin residue.

  Therefore, an object of the present invention is to provide a method for producing an all-solid battery capable of promoting the removal of a resin and an all-solid battery obtained by the production method.

  As a result of various studies by the inventors in order to solve the above-mentioned problems, at least the unfired body of the solid electrolyte layer contains a de-resin accelerator, and the unfired body is fired to promote resin removal. I found out that I can make it. Based on such knowledge of the inventors, the present invention has the following features.

A method for producing an all-solid battery according to the present invention includes a green body production step of producing a green body including at least one electrode layer of a positive electrode layer or a negative electrode layer, and a solid electrolyte layer containing a resin; A laminate forming step of laminating the unfired bodies to form a laminate, and a firing step of firing the laminate. In the green body preparation step, at least one selected from the group consisting of oxides, hydroxides, and oxyhydroxides as a de-resin accelerator for the green body including at least the solid electrolyte layer The compound is contained in an amount of 0.1% by weight or more.

  Moreover, it is preferable to include a transition metal containing compound 0.1 to 10weight% with respect to the material which comprises a non-fired body in a green body preparation process.

  Furthermore, in the green body production step, it is preferable to add the transition metal-containing compound to the green body by adding the transition metal-containing compound to the slurry forming the green body.

  Alternatively, in the green body preparation step, it is preferable to include the transition metal-containing compound in the green body by mixing the slurry that forms the green body and the solution containing the transition metal ions.

  The transition metal is preferably at least one selected from the group consisting of iron, nickel, copper, chromium, vanadium, silver, titanium, and niobium.

  Specifically, the transition metal-containing compound includes iron oxide, iron hydroxide, iron oxyhydroxide, nickel oxide, nickel hydroxide, nickel oxyhydroxide, copper oxide, chromium oxide, vanadium oxide, silver oxide, titanium oxide, In addition, at least one selected from the group consisting of niobium oxide is preferable.

  In the method for producing an all solid state battery of the present invention, the unfired body only needs to have the form of a green sheet or a printed layer.

  The solid electrolyte material included in the electrode layer and the solid electrolyte material included in the solid electrolyte layer preferably include a lithium-containing phosphate compound.

  The solid electrolyte material preferably includes a lithium-containing phosphate compound having a NASICON type structure.

  The all solid state battery of the present invention is manufactured by the manufacturing method having the above-described characteristics.

  According to the present invention, the removal of the resin can be promoted by adding the resin removal accelerator to the unfired body including at least the solid electrolyte layer and firing the unfired body. It becomes possible to suppress a decrease in performance.

It is sectional drawing which shows typically the cross-section of an all-solid-state battery laminated body as one embodiment of this invention. Solid iron oxide as deresination accelerator in the electrolyte layer (Fe ₂ O ₃₎ is a diagram showing the relationship between the content and conductivity. Solid in the electrolyte layer of iron oxide as deresination accelerator (Fe ₂ O ₃₎ is a diagram showing the relationship between the content and the carbon content. It is a figure which shows the relationship between the various de-resin promoters contained in a solid electrolyte layer, and conductivity. It is a figure which shows the relationship between the various de-resin promoters and carbon content which are contained in a solid electrolyte layer.

  As shown in FIG. 1, an all solid state battery laminate 10 as an embodiment to which the manufacturing method of the present invention is applied is a laminate in which a positive electrode layer 11, a solid electrolyte layer 13, and a negative electrode layer 12 are laminated in this order. Consists of. The positive electrode layer 11 is disposed on one surface of the solid electrolyte layer 13, and the negative electrode layer 12 is disposed on the other surface opposite to the one surface of the solid electrolyte layer 13. In other words, the positive electrode layer 11 and the negative electrode layer 12 are provided at positions facing each other with the solid electrolyte layer 13 interposed therebetween. Each of the positive electrode layer 11 and the negative electrode layer 12 includes at least an electrode active material, and may further include a solid electrolyte. The solid electrolyte layer 13 includes a solid electrolyte. Each of the positive electrode layer 11 and the negative electrode layer 12 may contain carbon, a metal, an oxide, etc. as an electronic conductive material.

  In order to manufacture the all-solid battery stack 10 configured as described above, in the present invention, first, an unfired body including at least one electrode layer of the positive electrode layer 11 or the negative electrode layer 12 and the solid electrolyte layer 13 is formed. Prepare (unfired body manufacturing step). Thereafter, the produced green body is laminated to form a laminated body (laminated body forming step). And the obtained laminated body is baked (baking process). In the green body preparation step, the green resin including at least the solid electrolyte layer 13 includes a deresin accelerator.

  In this way, the removal of the resin can be promoted by baking the green body by including the resin removal accelerator in the green body including at least the solid electrolyte layer 13. As a result, it is possible to suppress a decrease in battery performance due to the residual resin.

  Note that, when the green body including at least the solid electrolyte layer 13 is fired without including a resin removal accelerator, carbon or carbide as a resin residue remains in the solid electrolyte layer 13. Further, the solid electrolyte material that is the main component of the solid electrolyte layer 13 has a smaller action of decomposing or burning the resin than the electrode active material and the conductive material. The solid electrolyte layer 13 is the layer in which the resin is most difficult to remove. Therefore, electronic conductivity is generated in the solid electrolyte layer 13 due to the resin residue, which may cause an internal short circuit between the positive electrode layer 11 and the negative electrode layer 12 via the solid electrolyte layer 13. According to the present invention, the above-mentioned problem can be solved by adding the resin removal accelerator to the unfired body including at least the solid electrolyte layer 13 and firing the unfired body. It is possible to suppress a decrease in battery performance.

  If it is a material which has the effect which accelerates | stimulates the removal of resin, although the kind of deresin promoter is not limited, It is preferable that it is a transition metal containing compound.

  Moreover, it is preferable to include a transition metal containing compound 0.1 to 10weight% with respect to the material which comprises a non-fired body in a green body preparation process. If the content of the transition metal-containing compound is less than 0.1% by weight, the effect of promoting the decomposition or combustion of the resin in the firing step may not be sufficiently obtained. When the content is 0.1% by weight or more, the above-described effects can be obtained. If the content of the transition metal-containing compound exceeds 10% by weight, the ionic conductivity of the solid electrolyte layer 13 is greatly reduced, so that sufficient charge / discharge characteristics may not be obtained. If the amount is 10% by weight or less, the ionic conductivity inherently exhibited by the solid electrolyte material can be maintained.

  Furthermore, in the green body production step, it is preferable to add the transition metal-containing compound to the green body by adding the transition metal-containing compound to the slurry forming the green body. By adding the transition metal-containing compound to the slurry that forms the green body, it is possible to produce a green body in which the transition metal-containing compound is uniformly dispersed, so that the decomposition or combustion of the resin is promoted in the baking process. The effect can be obtained efficiently.

  Alternatively, in the green body preparation step, it is preferable to include the transition metal-containing compound in the green body by mixing the slurry that forms the green body and the solution containing the transition metal ions. In this case, in the step of drying the green body and removing the solvent contained in the slurry, the transition metal compound is precipitated on the surface of the inorganic material, that is, the solid electrolyte material, contained in the green body. An unfired body in which a metal-containing compound is uniformly dispersed can be produced, and an effect of promoting decomposition or combustion of the resin in the firing step can be efficiently obtained. The slurry and the solution containing transition metal ions may be mixed by directly dissolving the transition metal salt, complex salt, or the like in the slurry.

The material of the transition metal-containing compound is not limited as long as the material has an effect of promoting the resin removal, but the transition metal includes iron (Fe), nickel (Ni), copper (Cu), chromium (Cr), It is preferably at least one selected from the group consisting of vanadium (V), silver (Ag), titanium (Ti), and niobium (Nb). The transition metal-containing compound is preferably at least one selected from the group consisting of oxides, hydroxides, and oxyhydroxides. Specifically, the transition metal-containing compound includes iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ , FeO), iron hydroxide (Fe (OH) ₂ ), iron oxyhydroxide (FeOOH), nickel oxide (Ni ₂ O ₃ , NiO), nickel hydroxide (Ni (OH) ₂ ), nickel oxyhydroxide (NiOOH), copper oxide (CuO, Cu ₂ O), chromium oxide (Cr ₂ O ₃ ), vanadium oxide (V ₂ O ₅ , V ₂ O ₃ ), silver oxide (AgO, Ag ₂ O), titanium oxide (TiO ₂ ), and at least one selected from the group consisting of niobium oxide (Nb ₂ O ₅ ) are preferable. .

  In the method for producing an all solid state battery of the present invention, the unfired body only needs to have the form of a green sheet or a printed layer.

  The solid electrolyte material contained in at least one of the positive electrode layer 11 and the negative electrode layer 12 and the solid electrolyte material contained in the solid electrolyte layer 13 preferably contain a lithium-containing phosphate compound. The solid electrolyte material preferably includes a lithium-containing phosphate compound having a NASICON type structure.

  The all-solid-state battery stack 10 of the present invention is manufactured by a manufacturing method having the characteristics described above.

Although all types of electrode active material contained in the positive electrode layer 11 or negative electrode layer 12 of the solid battery stack 10 is not limited to the production method of the present invention is applied, as the cathode active material, Li ₃ V ₂ (PO ₄ ) Lithium-containing phosphoric acid compounds having a NASICON type structure such as _3, lithium-containing phosphoric acid compounds having an olivine type structure such as LiFePO ₄ and LiMnPO ₄ , LiCoO ₂ , LiCo _1/3 Ni _1/3 Mn _1/3 O A layered compound such as ₂ or a lithium-containing compound having a spinel structure such as LiMn ₂ O ₄ or LiNi _0.5 Mn _1.5 O ₄ can be used.

As the negative electrode active material, MOx (M is at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, and Mo, and x is in the range of 0.9 ≦ x ≦ 2.0. A compound having a composition represented by the following numerical value can be used. For example, a mixture in which two or more active materials having a composition represented by MOx containing different elements M such as TiO ₂ and SiO ₂ may be used. As the negative electrode active material, graphite-lithium compounds, lithium alloys such as Li-Al, oxidations such as Li ₃ V ₂ (PO ₄ ) ₃ , Li ₃ Fe ₂ (PO ₄ ) ₃ , Li ₄ Ti ₅ O ₁₂ Can be used.

Further, the type of the solid electrolyte contained in the positive electrode layer 11, the negative electrode layer 12, or the solid electrolyte layer 13 of the all-solid battery stack 10 to which the manufacturing method of the present invention is applied is not limited. A lithium-containing phosphate compound having a mold structure can be used. Lithium-containing phosphoric acid compound having a NASICON-type structure, the chemical formula _{Li x M y (PO 4)} 3 ( Formula, x 1 ≦ x ≦ 2, y is a number in the range of 1 ≦ y ≦ 2, M Is one or more elements selected from the group consisting of Ti, Ge, Al, Ga and Zr). In this case, part of P in the above chemical formula may be substituted with B, Si, or the like. Mixing two or more compounds having different compositions of lithium-containing phosphate compounds having a NASICON type structure, such as Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ and Li _1.2 Al _0.2 Ti _1.8 (PO ₄ ) ₃ You may use the mixture.

  In addition, the lithium-containing phosphate compound having a NASICON structure used in the above solid electrolyte includes a powder containing a crystal phase of a lithium-containing phosphate compound having a NASICON structure, or a lithium-containing phosphate having a NASICON structure by heat treatment You may use the glass which precipitates the crystal phase of a phosphoric acid compound.

In addition, as a material used for said solid electrolyte, it is possible to use the material which has ion conductivity and is so small that electronic conductivity can be disregarded other than the lithium-containing phosphate compound which has a NASICON structure. Examples of such a material include lithium halide, lithium nitride, lithium oxyacid salt, and derivatives thereof. In addition, Li—PO compounds such as lithium phosphate (Li ₃ PO ₄ ), LIPON (LiPO _4−x N _x ) in which nitrogen is mixed with lithium phosphate, and Li—Si—O such as Li ₄ SiO ₄ Compounds such as La-based compounds, Li-P-Si-O based compounds, Li-V-Si-O based compounds, La _0.51 Li _0.35 TiO _2.94 , La _0.55 Li _0.35 TiO ₃ , Li _3x La _{2 / 3-x} TiO ₃ Examples thereof include a compound having a lobskite structure, a compound having a garnet structure having Li, La, and Zr.

  At least one of the positive electrode material, the solid electrolyte material, and the negative electrode material of the all-solid-state battery stack 10 to which the manufacturing method of the present invention is applied includes a solid electrolyte composed of a lithium-containing phosphate compound having a NASICON structure. Is preferred. In this case, high ion conductivity that is essential for battery operation of an all-solid battery can be obtained. Further, when a glass powder or glass ceramic powder having a composition of a lithium-containing phosphate compound having a NASICON structure is used as a solid electrolyte, a denser sintered body can be easily obtained due to the viscous flow of the glass phase in the firing process. Therefore, it is particularly preferable to prepare the starting material for the solid electrolyte in the form of glass powder or glass ceramic powder.

  Moreover, it is preferable that at least one material of the positive electrode material or the negative electrode material of the all-solid-state battery stack 10 to which the manufacturing method of the present invention is applied includes an electrode active material made of a lithium-containing phosphate compound. In this case, the phase change of the electrode active material in the firing step or the reaction of the electrode active material with the solid electrolyte can be easily suppressed by the high temperature stability of the phosphoric acid skeleton. The capacity can be increased. In addition, when an electrode active material composed of a lithium-containing phosphate compound and a solid electrolyte composed of a lithium-containing phosphate compound having a NASICON structure are used in combination, the reaction between the electrode active material and the solid electrolyte is suppressed in the firing step. It is particularly preferable to use a combination of the electrode active material and the solid electrolyte material as described above, since both of them can be obtained and good contact can be obtained.

  Furthermore, the current collector layer formed in the all solid state battery stack 10 to which the manufacturing method of the present invention is applied includes an electron conductive material. The electron conductive material preferably contains at least one selected from the group consisting of conductive oxides, metals, and carbon materials.

You may seal the laminated body baked in the manufacturing method of said all-solid-state battery laminated body 10 in a coin cell, for example. The sealing method is not particularly limited. For example, you may seal the laminated body after baking with resin. Alternatively, an insulating paste having an insulating property such as Al ₂ O ₃ may be applied or dipped around the laminate, and the insulating paste may be heat-treated for sealing.

  Note that a current collector layer such as a carbon layer, a metal layer, or an oxide layer may be formed on the positive electrode layer 11 and the negative electrode layer 12 in order to efficiently draw current from the positive electrode layer 11 and the negative electrode layer 12. Examples of the method for forming the current collector layer include a sputtering method. Alternatively, the metal paste may be applied or dipped and heat-treated.

  In the laminate forming step, it is preferable to laminate the unfired bodies of the positive electrode layer 11, the solid electrolyte layer 13, and the negative electrode layer 12 to form an unfired laminated body having a single cell structure. Furthermore, in the laminated body forming step, a laminated body may be formed by laminating a plurality of laminated bodies having the above single cell structure with an unfired body of the current collector interposed therebetween. In this case, a plurality of laminates having a single battery structure may be laminated electrically in series or in parallel.

  The method for forming the green body is not particularly limited, but a doctor blade method, a die coater, a comma coater, or the like may be used to form a green sheet, or screen printing may be used to form a printing layer. it can. The method for laminating the unfired electrode layer and the unfired solid electrolyte layer is not particularly limited, but the unfired electrode layer and the unfired electrode layer may be formed using a hot isostatic press, a cold isostatic press, an isostatic press, or the like. A fired solid electrolyte layer can be laminated.

  The slurry for forming the green sheet or the printed layer includes an organic vehicle in which an organic material is dissolved in a solvent, and a positive electrode active material and a solid electrolyte, a negative electrode active material and a solid electrolyte, a solid electrolyte, or a current collector material. Can be prepared by wet mixing. Media can be used in wet mixing, and specifically, a ball mill method, a viscomill method, or the like can be used. On the other hand, a wet mixing method that does not use media may be used, and a sand mill method, a high-pressure homogenizer method, a kneader dispersion method, or the like can be used. The organic material contained in the slurry for forming the green sheet or the printing layer is not particularly limited, but polyvinyl acetal resin, cellulose resin, acrylic resin, urethane resin, vinyl acetate resin, polyvinyl alcohol resin, and the like can be used. The effect of the present invention can be obtained when the slurry contains at least one of these resins.

  The slurry may contain a plasticizer. Although the kind of plasticizer is not particularly limited, phthalic acid esters such as dioctyl phthalate and diisononyl phthalate may be used.

  In the firing step, the atmosphere is not particularly limited, but it is preferably performed under conditions that do not change the valence of the transition metal contained in the electrode active material. The firing temperature is preferably 400 ° C. or higher and 1000 ° C. or lower.

  Next, examples of the present invention will be specifically described. In addition, the Example shown below is an example and this invention is not limited to the following Example.

(Example A)
Hereinafter, a solid electrolyte layer is produced by firing a green sheet containing iron oxide (Fe ₂ O ₃ ), which is an example of a deresin accelerator, in a green sheet that is an unfired body of a solid electrolyte layer, An example of verifying the resin removal promoting effect will be described.

First, as Fe ₂ O ₃ powder as deresination accelerator is contained in weight percent shown in Table 1 below with respect to the main material of the solid electrolyte layer, Fe ₂ O ₃ powder and, Li as a solid electrolyte material by mixing a glass powder having a composition of _{1.4 Al 0.4 Ge 1.6 (PO 4} ) 3, to prepare a main material of the solid electrolyte layer of the sample No. 102 to 107. The main material of the solid electrolyte layer of sample number 101 is made of glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ as a solid electrolyte material. The obtained main material, polyvinyl acetal resin, and alcohol were mixed at a weight ratio of 85: 15: 140 to prepare a slurry for forming a solid electrolyte layer. The obtained slurry was formed into a green sheet having a thickness of 10 μm. The obtained green sheet was punched into a circular shape having a diameter of 10 mm. Ten circular green sheets were laminated to produce a green body of a solid electrolyte layer. In order to remove the polyvinyl acetal resin from the green body in a state where the green body is sandwiched between two porous ceramic plates, the green body is at a temperature of 500 ° C. in a nitrogen gas atmosphere containing 1% by volume of oxygen gas. After firing, a solid electrolyte layer fired body was fabricated by firing at a temperature of 650 ° C. in a nitrogen gas atmosphere.

  The appearance of the obtained solid electrolyte layers of sample numbers 101 to 107 was observed.

As a result, the solid electrolyte layer of Sample No. 101 that does not contain Fe ₂ O ₃ has an appearance of resin residue, that is, black or gray derived from carbon or carbide, and the resin residue of the solid electrolyte layer It was confirmed that a large amount remained inside. When a solid battery is manufactured using such a solid electrolyte layer, electronic conductivity is generated in the solid electrolyte layer, which may cause an internal short circuit between the positive electrode layer and the negative electrode layer via the solid electrolyte layer. Therefore, it is not preferable.

The solid electrolyte layer of the sample No. 102 to 107 Fe ₂ O ₃ content is 0.1 wt% or more, in accordance with Fe ₂ O ₃ content increases, the white appearance is derived from the solid electrolyte material The proportion occupied increased. The solid electrolyte layer of the sample No. 105 to 107 is Fe ₂ O ₃ content of 5.0 wt% or more, the appearance ratio of red brown from Fe ₂ O ₃ is increased. For the solid electrolyte layers of Sample Nos. 102 to 107 having an Fe ₂ O ₃ content of 0.1% by weight or more, black or gray derived from the resin residue is not confirmed, and the resin residue is relatively A small amount was confirmed. Therefore, it was confirmed that the removal of the resin proceeded effectively for the solid electrolyte layers of Sample Nos. 102 to 107 having an Fe ₂ O ₃ content of 0.1% by weight or more.

Next, electrodes were formed by sputtering platinum (Pt) of each of the obtained solid electrolyte layers of sample numbers 101 to 107, and the conductivity was measured under the conditions of a frequency of 0.1 to 1 MHz and an amplitude of 100 mV. When the obtained conductivity value was 1 × 10 ⁻² S / cm or more, it was judged that the electron conductivity was shown, and when it was 1 × 10 ⁻³ S / cm or less, the ionic conductivity was shown.

  Moreover, the carbon content contained in each of the solid electrolyte layers of sample numbers 101 to 107 was measured with a CS meter.

  These measurement results are shown in Table 1, FIG. 2 and FIG.

From Table 1 and FIG. 2, the conductivity of the solid electrolyte layer of sample numbers 102 to 106 having an Fe ₂ O ₃ content of 0.1 wt% or more and 10.0 wt% or less is 1 × 10 ⁻⁵ S / It was confirmed that the ion conductivity of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ which is a solid electrolyte material was exhibited. The solid electrolyte layer of sample number 101 that does not contain Fe ₂ O ₃ has a conductivity of 3.0 × 10 ⁻² S / cm, and electronic conductivity is generated in the solid electrolyte layer due to the resin residue. confirmed. It was confirmed that the ionic conductivity of the solid electrolyte layer of Sample No. 107 having an Fe ₂ O ₃ content of 20.0% by weight was greatly reduced.

From Table 1 and FIG. 3, it was confirmed that the carbon content contained in the solid electrolyte layer decreased as the Fe ₂ O ₃ content increased.

Therefore, by including Fe ₂ O ₃ which is an example of a deresin accelerating agent in the green sheet which is an unfired body of the solid electrolyte layer, the effect of removing the resin is promoted, and the Fe ₂ O ₃ content, That is, it was confirmed that the content of the deresin accelerator is preferably 0.1% by weight or more and 10.0% by weight or less.

(Example B)
Hereinafter, a solid electrolyte layer is produced by firing a green sheet by including various transition metal oxides as a de-resin accelerator in a green sheet which is an unfired body of a solid electrolyte layer, thereby promoting the resin removal promotion effect. An example of verifying the above will be described.

First, the transition metal oxide powder and Li _1.4 Al _0.4 as the solid electrolyte material were contained so that the transition metal oxide powder shown in Table 2 below was contained at 3.0% by weight with respect to the main material of the solid electrolyte layer. by mixing a glass powder having a composition of Ge _1.6 (PO _{4) 3,} to prepare a main material of the solid electrolyte layer of the sample No. 202-212. The main material of the solid electrolyte layer of sample number 201 is made of glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ as a solid electrolyte material.

  A fired body of the solid electrolyte layer was produced in the same manner as the production method described in Example A.

  The appearance of the obtained solid electrolyte layers of sample numbers 201 to 212 was observed.

  As a result, the solid electrolyte layer of Sample No. 201 containing no resin removal accelerator has a black or gray appearance derived from a resin residue, that is, carbon or carbide, and the resin residue is a solid electrolyte layer. It was confirmed that a large amount remained inside. With respect to the solid electrolyte layers of Sample Nos. 202 to 212 containing the deresin accelerator, a clear black color derived from the resin residue, that is, carbon or carbide, was not observed in the appearance.

  Next, the conductivity and carbon content of each of the obtained solid electrolyte layers of Sample Nos. 201 to 212 were measured in the same manner as the measurement method described in Example A.

  These measurement results are shown in Table 2 and FIGS.

From Table 2 and FIG. 4, the solid electrolyte layer of sample number 201 that does not contain the deresin accelerator has a conductivity of 3.0 × 10 ⁻² S / cm, and the resin residue causes electrons in the solid electrolyte layer. It was confirmed that conductivity occurred. The conductivity of the solid electrolyte layer of Sample Nos. 202 to 212 containing the deresin accelerator is in the range of 1 × 10 ⁻⁶ to 10 × 10 ⁻⁴ S / cm, and Li _1.4 Al _0.4 Ge which is a solid electrolyte material. It was confirmed that _1.6 (PO ₄ ) ₃ exhibited ionic conductivity.

  From Table 2 and FIG. 5, the carbon content of the solid electrolyte layers of sample numbers 202 to 212 including the deresin accelerator is higher than that of the solid electrolyte layer of sample number 201 not including the deresin accelerator. It was confirmed that the carbon content contained in the layer decreased.

  Therefore, it was confirmed that the effect of removing the resin was promoted by including various transition metal oxides as a de-resin accelerator in the green sheet which is an unfired body of the solid electrolyte layer.

In Embodiments A and B described above, α-Fe ₂ O ₃ (III) was used as Fe ₂ O ₃ as a deresin accelerator, but other crystal forms of iron oxide such as β phase and γ phase were used. May be used. As TiO ₂ , anatase-type titanium oxide was used, but other crystal forms may be used. Other transition metal oxides may be in any crystal form as long as the effect of removing the resin can be obtained.

(Example C)
Hereinafter, Examples 1 to 11 of the all-solid battery produced by firing a green sheet containing a deresin accelerator and Comparative Example 1 of an all-solid battery produced by firing a green sheet not containing a deresin accelerator explain.

  First, in order to produce the all solid state batteries of Examples 1 to 11 and Comparative Example 1, as a starting material for the positive electrode layer, the negative electrode layer, and the solid electrolyte layer, each main material was prepared as follows, Each slurry was produced and each green sheet was produced using each slurry.

<Preparation of each main material>
<Preparation of positive electrode main material 1>
A powder having a crystal phase of a NASICON structure having a composition of Li ₃ V ₂ (PO ₄ ) _{3 as} a positive electrode active material and a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ as a solid electrolyte material A powder obtained by mixing glass powder and carbon powder as a conductive agent at a weight ratio of 45:45:10 was used as a main material.

<Preparation of positive electrode main material 2>
A powder having a crystal phase of a NASICON structure having a composition of Li ₃ V ₂ (PO ₄ ) _{3 as} a positive electrode active material and a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ as a solid electrolyte material A powder obtained by mixing glass powder, carbon powder as a conductive agent, and Fe ₂ O ₃ powder as a deresin accelerating agent in a weight ratio of 45: 44: 10: 1 was used as a main material.

<Preparation of solid electrolyte main material 1>
Glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ was used as a main material.

<Preparation of solid electrolyte main material 2>
A powder obtained by mixing glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and Fe ₂ O ₃ powder as a deresin accelerating agent at a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 3>
A powder obtained by mixing glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and Fe ₃ O ₄ powder as a deresin accelerating agent at a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 4>
A powder obtained by mixing a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and CuO powder as a deresin accelerating agent in a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 5>
A powder obtained by mixing glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and Cu ₂ O powder as a deresin accelerating agent at a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 6>
A powder obtained by mixing a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and a V ₂ O ₅ powder as a resin removal accelerator at a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 7>
A powder obtained by mixing a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and a V ₂ O ₃ powder as a deresin accelerating agent at a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 8>
A powder obtained by mixing a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and Ag ₂ O powder as a deresin accelerating agent at a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 9>
A powder obtained by mixing glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and TiO ₂ powder as a deresin accelerating agent in a weight ratio of 99: 1 was used as a main material.

<Preparation of solid electrolyte main material 10>
A powder obtained by mixing a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ and Nb ₂ O ₅ powder, which is a resin removal accelerator, at a weight ratio of 99: 1 was used as a main material.

<Preparation of negative electrode main material 1>
A powder having a crystal phase of anatase-type titanium oxide (TiO ₂ ) as a negative electrode active material, a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ as a solid electrolyte material, and a conductive material A powder obtained by mixing carbon powder at a weight ratio of 45:45:10 was used as a main material.

<Preparation of negative electrode main material 2>
A powder having a crystal phase of anatase-type titanium oxide (TiO ₂ ) as a negative electrode active material, a glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ as a solid electrolyte material, and a conductive material A powder obtained by mixing carbon powder and Fe ₂ O ₃ powder, which is a deresinification accelerator, at a weight ratio of 45: 44: 10: 1 was used as a main material.

<Preparation of each slurry>
Each main material prepared above, polyvinyl acetal resin, and alcohol are mixed at a mass ratio of 85: 15: 140, and positive electrode slurries 1 and 2, solid electrolyte slurries 1 to 10, and negative electrode slurries 1 and 2 are mixed. Was made.

The solid electrolyte slurry 11 was produced as follows. A glass powder having a composition of Li _1.4 Al _0.4 Ge _1.6 (PO ₄ ) ₃ , a polyvinyl acetal resin, and an alcohol in which 0.03 M iron (III) chloride hexahydrate is dissolved, 85: 15: 140 The solid electrolyte slurry 11 was prepared by mixing at a weight ratio (this corresponds to a case where a slurry forming a green sheet as an unfired body and a solution containing transition metal ions as a de-resin accelerator are mixed. To do). In addition, since the weight ratio of the solid electrolyte material contained in the solid electrolyte slurry 11 and the iron chloride dissolved in the slurry is approximately 99: 1, the content of the deresin accelerator included in the solid electrolyte slurry 11 is It was equivalent to the solid electrolyte slurry 2-10.

<Production of each green sheet>
Each slurry prepared above is formed into a sheet so that the thickness is 10 μm, and further cut to have a planar size of 25 mm × 15 mm, and the positive electrode layer sheets 1 and 2, the solid electrolyte layer sheets 1 to 11, Negative electrode layer sheets 1 and 2 were prepared.

<Preparation of all-solid battery>
Using the positive electrode layer sheets 1 and 2, the solid electrolyte layer sheets 1 to 11, and the negative electrode layer sheets 1 and 2 obtained as described above, all solid state batteries of Examples 1 to 11 and Comparative Example 1 were produced. did. The structures of the green sheets used for the positive electrode layer, the solid electrolyte layer, and the negative electrode layer of the all solid state batteries of Examples 1 to 11 and Comparative Example 1 are as shown in Table 3 below.

  By laminating three positive electrode layer sheets, ten solid electrolyte layer sheets, and two negative electrode layer sheets in this order, each laminate of Examples 1 to 11 and Comparative Example 1 was prepared. Each laminate was further cut to a planar size of 10 mm × 10 mm. Then, in a state where each laminate is sandwiched between two porous ceramic plates, a temperature of 500 ° C. is used in a nitrogen gas atmosphere containing 1% by volume of oxygen gas in order to remove the polyvinyl acetal resin from the green body. After firing, firing was performed at a temperature of 650 ° C. in a nitrogen gas atmosphere, so that all-solid battery stacks of Examples 1 to 11 and Comparative Example 1 were produced as fired bodies.

  A platinum (Pt) layer was formed as a current collector layer on the surfaces of the positive electrode layer and the negative electrode layer by sputtering. Then, after drying at the temperature of 100 degreeC and removing a water | moisture content, it sealed with the 2032 type | mold coin cell, and produced the all-solid-state battery of Examples 1-11 and the comparative example 1.

<Evaluation of all solid state battery>
The solid batteries of Examples 1 to 11 and Comparative Example 1 obtained as described above were placed in a thermostatic bath maintained at a temperature of 25 ° C., and the current was about 0.2 C with respect to the weight of the positive electrode active material. The battery was charged to a voltage of 3.25 V with a corresponding current of 60 μA, held at a voltage of 3.25 V for 5 hours, then rested for 3 hours, discharged to a voltage of 0 V with a current of 60 μA, and then rested for 3 hours. This cycle was performed three times, and the discharge capacity at the third cycle is shown in Table 4 below.

  From the above results, it is considered that the all-solid-state battery of Comparative Example 1 in which the solid electrolyte layer does not contain a resin removal accelerator has a very small discharge capacity, causing an internal short circuit between the positive and negative electrode layers via the solid electrolyte layer. It was confirmed that the all-solid-state batteries of Examples 1 to 11 in which the solid electrolyte layer contains a resin removal accelerator have a high discharge capacity and excellent charge / discharge characteristics. In particular, the all-solid-state battery of Example 10 in which the positive and negative electrode layers and the solid electrolyte layer contain a de-resin accelerator is more discharged than the all-solid battery of Example 1 in which the same kind of de-resin accelerator is contained only in the solid electrolyte layer. It was confirmed that the charge and discharge characteristics were improved when the capacity was high and the positive and negative electrode layers contained a resin removal accelerator.

  It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

  The removal of the resin can be promoted by including the resin removal accelerator in the unfired body including at least the solid electrolyte layer, and the deterioration of the battery performance due to the residual resin is suppressed. The present invention is particularly useful in the production of solid state batteries.

10: all-solid battery stack, 11: positive electrode layer, 12: negative electrode layer, 13: solid electrolyte layer.

Claims (10)

An unsintered body preparation step of preparing an unsintered body including at least one electrode layer of the positive electrode layer or the negative electrode layer and a solid electrolyte layer containing a resin;
A laminated body forming step of forming a laminated body by laminating the green body;
A firing step of firing the laminate,
In the green body preparation step, at least one transition selected from the group consisting of oxides, hydroxides, and oxyhydroxides as a deresin accelerator for the green body including at least the solid electrolyte layer A method for producing an all-solid-state battery, comprising 0.1% by weight or more of a metal-containing compound.   2. The method for producing an all-solid battery according to claim 1, wherein in the green body manufacturing step, the transition metal-containing compound is included in an amount of 0.1 wt% or more and 10 wt% or less with respect to a material constituting the green body. .   In the said green body preparation process, the said transition metal containing compound is included in the said green body by adding the said transition metal containing compound to the slurry which forms the said green body. The manufacturing method of the all-solid-state battery of description.   In the said unsintered body preparation process, the said transition metal containing compound is included in the said unsintered body by mixing the slurry which forms the said unsintered body, and the solution containing the said transition metal ion. Item 3. A method for producing an all-solid-state battery according to Item 2.   The transition metal according to any one of claims 1 to 4, wherein the transition metal is at least one selected from the group consisting of iron, nickel, copper, chromium, vanadium, silver, titanium, and niobium. Manufacturing method of all solid state battery. The transition metal-containing compound is iron oxide, iron hydroxide, iron oxyhydroxide, nickel oxide, nickel hydroxide, nickel oxyhydroxide, copper oxide, chromium oxide, vanadium oxide, silver oxide, titanium oxide, and niobium oxide. The manufacturing method of the all-solid-state battery of any one of Claim 1- Claim 5 which is at least 1 type chosen from the group which consists of. The said green body is a manufacturing method of the all-solid-state battery of any one of Claim 1- Claim 6 which has a form of a green sheet or a printing layer. The solid electrolyte according to any one of claims 1 to 7 , wherein the solid electrolyte material included in the electrode layer and the solid electrolyte material included in the solid electrolyte layer include a lithium-containing phosphate compound. Battery manufacturing method. The manufacturing method of the all-solid-state battery of Claim 8 with which the said solid electrolyte material contains the lithium containing phosphoric acid compound which has a NASICON type | mold structure. The all-solid-state battery manufactured by the manufacturing method of any one of Claim 1- Claim 9 .

Images