JP2011001221A - Method for producing sheet containing lithium phosphorus oxynitride compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a sufficiently flexible sheet containing a lithium phosphorus oxynitride compound.SOLUTION: The present invention solves the problem by providing a method for producing a sheet containing a lithium phosphorus oxynitride compound comprising the preparation step of preparing a raw material composition containing a raw material compound having an Li element and a POskeleton, a nitrogen-containing compound which nitrides the raw material compound and has polymerizability, and a strong alkali compound, the synthesis step of obtaining a lithium phosphorus oxynitride compound-containing composition by performing the synthesis from the raw material composition into the lithium phosphorus oxynitride and the polymerization of the nitrogen-containing compound by firing the raw material composition, and the molding step of molding the lithium phosphorus oxynitride compound-containing composition into a sheet.

Description

  The present invention relates to a method for producing a lithium nitride phosphate compound-containing sheet containing a lithium nitride phosphate compound useful as, for example, a solid electrolyte or an active material.

  With the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones in recent years, development of batteries that are used as power sources has been regarded as important. Also in the automobile industry and the like, development of high-power and high-capacity batteries for electric vehicles or hybrid vehicles is being promoted. Currently, lithium batteries are attracting attention from the viewpoint of high energy density among various batteries.

  The lithium battery currently on the market uses an organic electrolyte that uses a flammable organic solvent as a solvent. Improvement is required. In contrast, an all-solid-state lithium battery in which the liquid electrolyte is changed to a solid electrolyte to make the battery all solid does not use a flammable organic solvent in the battery. Excellent productivity.

  As such a solid electrolyte, for example, an oxide solid electrolyte is known, and it is generally known that an oxide solid electrolyte has low Li ion conductivity. On the other hand, among oxide solid electrolytes, LIPON (a general term for nitrides of lithium phosphate) has high Li ion conductivity and is stable against oxidation and reduction. It is attracting attention as an electrolyte. Conventionally, several methods are known as a synthesis method of LIPON.

  For example, Patent Document 1 discloses a method of forming a lithium nitride lithium phosphate thin film by resistance heating vapor deposition. Patent Document 2 discloses a method of forming lithium nitride lithium phosphate by mixing and firing lithium phosphate and urea.

JP 2004-183078 A Japanese Patent Application No. 2008-260803

  The lithium nitride phosphoric acid thin film described in Patent Document 1 has a problem that it is not flexible and easily peels off and cracks. This invention is made | formed in view of the said problem, and it aims at providing the manufacturing method of the lithium nitride phosphate compound containing sheet | seat excellent in the softness | flexibility.

In order to achieve the above object, the present invention includes a raw material compound having an Li element and a PO ₄ skeleton, a nitrogen-containing compound that nitrides the raw material compound and has polymerizability, and a strong alkali compound. The raw material composition is prepared, and the raw material composition is baked to synthesize the raw material compound into the lithium nitride phosphate compound and polymerize the nitrogen-containing compound. There is provided a method for producing a lithium nitride phosphate compound-containing sheet, comprising: a synthesis step for obtaining a product; and a molding step for forming the lithium nitride phosphate compound-containing composition into a sheet.

  According to the present invention, by using a nitrogen-containing compound that has both the property of nitriding a raw material compound and the polymerizability, a lithium nitride phosphate compound-containing sheet having excellent flexibility can be efficiently obtained.

In the above invention, the starting compound is preferably a _Li 3 PO _4. Moreover, in the said invention, it is preferable that the said raw material compound is a compound which has a NASICON (LISICON) type | mold structure. For example, a sheet useful as a solid electrolyte layer forming sheet can be obtained.

  In the said invention, it is preferable that the said raw material compound is a compound which has an olivine type structure. For example, a sheet useful as a positive electrode active material layer forming sheet can be obtained.

  In the above invention, the nitrogen-containing compound preferably has at least two amino groups. In particular, the nitrogen-containing compound is preferably urea. This is because nitriding of the raw material compound and polymerization of the nitrogen-containing compound can be performed efficiently.

  In the said invention, it is preferable that the said strong alkali compound is calcium hydroxide or lithium hydroxide. This is because the nitrogen-containing compound can be polymerized efficiently.

  In the said invention, it is preferable that the said raw material composition contains the compound which has polymerizability other than the said nitrogen-containing compound. Furthermore, the compound having polymerizability other than the nitrogen-containing compound is preferably formaldehyde. This is because the flexibility can be further improved.

  In the said invention, it is preferable that the calcination temperature in the said synthetic | combination process exists in the range of 150 to 250 degreeC. If the firing temperature is too low, the raw material compound may not be sufficiently nitrided, and if the firing temperature is too high, the nitrogen-containing compound polymer may be excessively decomposed.

  The present invention also provides a lithium nitride phosphate compound-containing sheet comprising a lithium nitride phosphate compound and a nitrogen-containing compound polymer obtained by polymerizing a nitrogen-containing compound.

  According to the present invention, since the lithium nitride phosphate compound and the nitrogen-containing compound polymer are complexed, a lithium nitride phosphate compound-containing sheet having excellent flexibility can be obtained.

  In the said invention, it is preferable that the ratio of the said nitrogen-containing compound polymer exists in the range of 5 volume%-30 volume%. If the proportion of the nitrogen-containing compound polymer is too small, the desired flexibility may not be obtained, and if the proportion of the nitrogen-containing compound polymer is too large, the Li ion conductivity may be lowered. It is.

  In this invention, there exists an effect that the lithium nitride phosphoric acid compound containing sheet | seat excellent in the softness | flexibility can be obtained efficiently. Furthermore, since the lithium nitride phosphate compound is excellent in Li ion conductivity, a lithium nitride phosphate compound-containing sheet excellent in Li ion conductivity can be obtained.

It is explanatory drawing which shows an example of the manufacturing method of the lithium nitride nitride compound containing sheet | seat of this invention. It is a schematic sectional drawing which shows an example of the lithium nitride phosphoric acid compound containing sheet | seat of this invention.

  Hereinafter, the method for producing a lithium nitride phosphate compound-containing sheet of the present invention and the lithium nitride phosphate compound-containing sheet will be described in detail.

A. First, a method for manufacturing a lithium nitride phosphate compound-containing sheet of the present invention will be described. The method for producing a lithium nitride phosphate compound-containing sheet of the present invention includes a raw material compound having an Li element and a PO ₄ skeleton, a nitrogen-containing compound that nitrides the raw material compound and has polymerizability, a strong alkali compound, A preparation step of preparing a raw material composition containing nitrile, and baking the raw material composition to synthesize the raw material compound into a lithium nitride phosphoric acid compound and to polymerize the nitrogen-containing compound. It comprises a synthesis step for obtaining a containing composition and a molding step for molding the lithium nitride phosphate compound-containing composition into a sheet.

In addition, the “lithium nitride phosphate compound” in the present invention refers to a compound having at least a Li element, a PO ₄ skeleton, and an N element, and further includes other elements (for example, transition metal elements) described later. Also good. In addition, the “PO ₄ skeleton” in the present invention is not limited to a skeleton composed of exact PO ₄ but also includes a skeleton composed of the vicinity thereof. When the P element constituting the PO ₄ skeleton is 1, the O element constituting the PO ₄ skeleton is preferably in the range of 2 to 6, and more preferably in the range of 3 to 4.

  According to the present invention, by using a nitrogen-containing compound that has both the property of nitriding a raw material compound and the polymerizability, a lithium nitride phosphate compound-containing sheet having excellent flexibility can be efficiently obtained. Furthermore, since the lithium nitride phosphate compound is excellent in Li ion conductivity, a lithium nitride phosphate compound-containing sheet excellent in Li ion conductivity can be obtained. Moreover, the reason why the lithium nitride phosphate compound-containing sheet obtained by the present invention is excellent in flexibility and flexibility is that the nitrogen-containing compound contained in the raw material composition is polymerized, This is considered to be because the sheet becomes a composite with the nitrogen-containing compound polymer.

FIG. 1 is an explanatory view showing an example of a method for producing a lithium nitride phosphate compound-containing sheet of the present invention. In FIG. 1, first, lithium orthophosphate (Li ₃ PO ₄ ) is prepared as a raw material compound having an Li element and a PO ₄ skeleton, the raw material compound is nitrided, and urea is prepared as a nitrogen-containing compound having polymerizability. Calcium hydroxide is prepared as a strong alkali compound. Next, these are mixed and a raw material composition is prepared (preparation process). Thereafter, the obtained raw material composition is baked, for example, in a vacuum state at 200 ° C., thereby nitriding Li ₃ PO ₄ and simultaneously polymerizing urea (synthesis step). Thereby, a nitrided lithium phosphate compound-containing composition in which nitrided Li ₃ PO ₄ is dispersed in polymerized urea is obtained. Finally, the obtained lithium nitride nitride compound-containing composition is molded into a sheet by a roll press (molding step). Thereby, a nitrided lithium phosphate compound-containing sheet is obtained. Next, the polymerization of urea will be described.

In the formula (1), two ureas react with each other in the presence of KOH as an alkali catalyst to form biuret. On the other hand, in the formula (2), a plurality of ureas react in the presence of KOH as an alkali catalyst to form polymerized urea. Moreover, although not shown, when three ureas react, cyanuric acid (trimer) is formed. Thus, by polymerizing urea, dimers, trimers and higher polymers are formed. Thereby, the lithium nitride phosphoric acid compound containing sheet | seat excellent in the softness | flexibility is obtained.
Hereinafter, the manufacturing method of the lithium nitride phosphoric acid compound containing sheet | seat of this invention is demonstrated for every process.

1. Preparation Step The preparation step in the present invention is a raw material composition containing a raw material compound having an Li element and a PO ₄ skeleton, a nitrogen-containing compound that nitrides the raw material compound and has polymerizability, and a strong alkali compound. Is a step of preparing

(1) Raw material compound starting compound in the present invention are those having a Li element and PO ₄ backbone. The raw material compound may be a single compound or a mixture of a compound having an Li element and a compound having a PO ₄ skeleton. In the former case, the use of the raw material compound having both the Li element and the PO ₄ skeleton has an advantage that the lithium nitride phosphate compound can be obtained more easily.

(I) Raw material compound having both Li element and PO ₄ skeleton First, a raw material compound having both Li element and PO ₄ skeleton will be described. As an example of the raw material compound having both the Li element and the PO ₄ skeleton, Li ₃ PO ₄ can be given. Li ₃ PO ₄ has three Li, and a lithium nitride lithium phosphate compound having high Li ion conductivity can be obtained. Moreover, raw material compound having both Li element and PO ₄ backbone, in addition to the Li element and PO ₄ skeleton may have an element turns into gas by calcination. Examples of such a compound include Li ₂ HPO ₄ and LiH ₂ PO ₄ .

Moreover, raw material compound having both Li element and PO ₄ backbone, in addition to the Li element and PO ₄ skeleton may have other elements. By using such a compound, for example, a solid electrolyte or an active material excellent in Li ion conductivity can be obtained.

Examples of such a compound include a compound having a NASICON (LISICON) type structure. A compound having a NASICON (LISICON) type structure is useful, for example, as a solid electrolyte. The compound having a NASICON (LISICON) structure, for _{example, Li a X b Y c P} d O e ( X is at least one kind selected Ti, Zr, Ge, In, Ga, from the group consisting of Sn and Al Y is at least one selected from the group consisting of B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se, and a to e are 0.5 <a <5. 0, 0.5 ≦ b <3.0, 0 ≦ c <2.98, 0.02 <d ≦ 3.0, 2.0 <c + d <4.0, 3.0 <e ≦ 12.0 (Satisfying relationship) (sometimes referred to as compound (I)).

Examples of compound (I) include Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ and Li _1.3 Si _0.3 Ti ₂ P _2.7 O ₁₂ .

Further, the raw material compound having both the Li element and the PO ₄ skeleton may be a compound having an olivine structure. A compound having an olivine structure is useful, for example, as a positive electrode active material. Examples of the compound having an olivine structure include a compound represented by LiMPO ₄ (M is at least one selected from the group consisting of Ni, Mn, Co, and Fe), and a compound having a composition in the vicinity thereof. Etc.

Another example of the raw material compound having an olivine type structure is Li _{a Xb} Y _{cP d} O _e (X is at least one selected from the group consisting of Mn, Fe, Co and Ni, and Y Is at least one selected from the group consisting of Mg, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In and Zn, and a to e are 0.001 ≦ a ≦ 1.5, 0.7 ≦ b ≦ 1.3, 0 ≦ c ≦ 0.4, 0.7 ≦ b + c ≦ 1.3, 0.7 ≦ d ≦ 1.3, 3.0 ≦ e ≦ 5.0 And a compound represented by (sometimes referred to as compound (II)).

Other examples of the raw material compound having an olivine type structure include Li _{a Xb} Y _{cP d} O _e F _f (X is at least one selected from the group consisting of Mn, Fe, Co, and Ni, and Y Is at least one selected from the group consisting of Mg, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In and Zn, and a to f are 0.001 ≦ a ≦ 1.5, 0.7 ≦ b ≦ 1.3, 0 ≦ c ≦ 0.4, 0.7 ≦ b + c ≦ 1.3, 0.7 ≦ d ≦ 1.3, 3.0 ≦ e ≦ 5.0, 0. 002 ≦ f ≦ 2.0) (sometimes referred to as compound (III)).

In this invention, you may have the synthetic | combination process which synthesize | combines previously the raw material compound before a preparation process. By synthesizing in advance, there is an advantage that the reaction control becomes easy when synthesizing the lithium nitride phosphoric acid compound. The method for synthesizing the above-mentioned compounds (I) to (III) is not particularly limited, and examples thereof include a mechanical milling method. The type and conditions of the mechanical milling method will be described later. As a method of synthesizing compound (III), for example, a method of synthesizing compound (III) using a mixture containing Li source, X source, Y source, PO ₄ source and F source, Examples include a method of synthesizing LiXYPO using a mixture containing a source, an X source, a Y source, and a PO ₄ source, and then synthesizing compound (III) using a LiXYPO and an F source. Of these, the former method is preferred in the present invention. This is because F can be introduced more efficiently. In addition, when “c” in compounds (I) to (III) is 0, the Y source is not used. In addition, the composition of the raw materials usually corresponds to the composition of the target compound.

(Ii) Mixture of compound having Li element and compound having PO ₄ skeleton As described above, the raw material compound in the present invention may be a mixture of a compound having Li element and a compound having PO ₄ skeleton. . In this case, there is an advantage that the ratio of the Li element and the PO ₄ skeleton is easily adjusted. Examples of the compound having Li element include Li ₂ CO ₃ , Li ₂ O, LiNO ₂ , LiNO ₃ , LiCl, CH ₃ COOLi, Li ₂ C ₂ O ₄ , LiOH, LiH, and Li ₃ P. . Especially, it is preferable that the compound which has Li element is a compound from which structural components other than Li element become gas by baking. This is because it is difficult to adversely affect the composition of the target lithium nitride phosphate compound. In particular, in the present invention, the compound containing Li element is preferably Li ₂ CO ₃ .

Examples of the compound having a PO ₄ skeleton include (NH ₄ ) H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , (NH ₄ ) ₃ PO _4, and H ₃ PO ₄ . Of these, compounds having a PO ₄ skeleton is preferably a component other than PO ₄ skeleton is a compound turns into gas. This is because it is difficult to adversely affect the composition of the target lithium nitride phosphate compound. Furthermore, from the viewpoint of promoting the synthesis of the lithium nitride phosphate compound, the compound having a PO ₄ skeleton preferably contains a nitrogen element. From such a viewpoint, the compound having a PO ₄ skeleton is preferably (NH ₄ ) H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ or (NH ₄ ) ₃ PO ₄ . In particular, in the present invention, the compound having a PO ₄ skeleton is preferably (NH ₄ ) H ₂ PO ₄ .

The raw material compound in the present invention may be a mixture of a Li source, an X source, a Y source and a PO ₄ source from which the above-described compound (I) or compound (II) can be obtained. Here, examples of the Li source and the PO ₄ source include the same compounds as the above-mentioned “compound having Li element” and “compound having PO ₄ skeleton”, respectively. The X source is not particularly limited as long as it is a compound containing an X element, and may be an organic compound or an inorganic compound. Examples of the X source include oxalic acid compounds and carbonic acid compounds. The same applies to the Y source. The Li source may further contain at least one of an X element, a Y element, and a PO ₄ skeleton. The same applies to the X source, the Y source, and the PO ₄ source. For example, the Li source may contain an X element in addition to the Li element.

In addition, the raw material compound in the present invention may be a mixture of a Li source, an X source, a Y source, a PO ₄ source and an F source from which the above-described compound (III) can be obtained. In this case, the composition of the mixture usually corresponds to the composition of compound (III). In addition, when “c” in compound (III) is 0, usually no Y source is used. The Li source, X source, Y source, and PO ₄ source are the same as described above. The F source may further contain at least one of Li element, X element, Y element, and PO ₄ skeleton. The same applies to the Li source, the X source, the Y source, and the PO ₄ source. For example, the F source may contain a Li element in addition to the F element. Specifically, LiF etc. can be mentioned.

When a compound having an Li element and a compound having a PO ₄ skeleton are used separately, the addition amount of both compounds is preferably appropriately selected according to the composition of the target lithium nitride phosphate compound. For example, when lithium nitride phosphate is synthesized, assuming that Li in the compound having Li element is 100 mol parts, the PO ₄ skeleton in the compound having PO ₄ skeleton is, for example, in the range of 10 mol parts to 100 mol parts It is preferable that it is in the range of 30 to 60 mol parts.

(2) Nitrogen-containing compound Next, the nitrogen-containing compound in the present invention will be described. The nitrogen-containing compound in the present invention is a material that nitrides the raw material compound and has polymerizability. In the present invention, a lithium nitride phosphate compound-containing sheet having excellent flexibility can be easily produced by using a nitrogen-containing compound that has both the property of nitriding a raw material compound and the polymerizability.

  The nitrogen-containing compound in the present invention is not particularly limited as long as the raw material compound is nitrided and has polymerizability. Among them, the nitrogen-containing compound in the present invention preferably has at least two amino groups, and particularly preferably has two amino groups. This is because nitriding of the raw material compound and polymerization of the nitrogen-containing compound can be performed efficiently. Examples of the nitrogen-containing compound in the present invention include urea, biuret, cyanuric acid, etc. Among them, urea is preferable.

  The nitrogen-containing compound in the present invention is usually solid or liquid at normal temperature (25 ° C.). By being solid or liquid, a raw material composition in which the nitrogen-containing compound and the raw material compound are in physical contact with each other can be produced efficiently, and the nitriding efficiency of the raw material compound is improved.

  The addition amount of the nitrogen-containing compound is preferably selected as appropriate according to the composition of the target lithium nitride phosphate compound and the target content of the nitrogen-containing compound polymer. When Li in the raw material compound is 100 mol parts, N in the nitrogen-containing compound is preferably in the range of 10 mol parts to 1000 mol parts, for example, and in the range of 100 mol parts to 500 mol parts. More preferred.

(3) Strong alkali compound Next, the strong alkali compound in this invention is demonstrated. The strong alkali compound in the present invention contributes to the polymerization of the nitrogen-containing compound. Examples of the strong alkali compound include calcium hydroxide, lithium hydroxide, sodium hydroxide, magnesium hydroxide, potassium hydroxide and the like. Further, the content of the strong alkali compound in the raw material composition is usually an amount capable of causing the polymerization of the nitrogen-containing compound, and is preferably, for example, 50% by weight or less. Moreover, in this invention, in order to improve the dispersibility of a strong alkali compound, the raw material composition may contain a small amount of water. The content of water is preferably the same as the content of the strong alkali compound, for example.

(4) Other components The raw material composition in the present invention contains at least the raw material compound, the nitrogen-containing compound and the strong alkali compound described above. In the present invention, the raw material composition may further contain a polymerizable compound other than the nitrogen-containing compound. Examples of the polymerizable compound other than the nitrogen-containing compound include compounds that are copolymerized with the nitrogen-containing compound, and specific examples include formaldehyde. For example, when the nitrogen-containing compound is urea, a urea resin can be formed by adding formaldehyde to the raw material composition. A specific reaction formula is shown below.

  In formula (3), urea and formaldehyde react (addition reaction) to form an alcohol. Furthermore, in Formula (4), urea resin is formed by dehydration condensation of the obtained alcohol.

  The content of the compound that is copolymerized with the nitrogen-containing compound in the raw material composition is preferably, for example, 50% by weight or less. This is because, within the above range, a lithium nitride phosphoric acid compound-containing sheet having more flexibility can be obtained.

  Moreover, when the raw material compound in this invention is used as a positive electrode active material, the raw material composition may contain the electrically conductive material further. This is because a lithium nitride nitride compound-containing sheet (positive electrode active material layer forming sheet) having excellent conductivity can be obtained. Examples of the conductive material include acetylene black, ketjen black, and carbon fiber.

(5) Preparation of raw material composition The raw material composition in the present invention contains at least the raw material compound, the nitrogen-containing compound and the strong alkali compound described above. As a preparation method of a raw material composition, the method of mixing a raw material compound etc. can be mentioned, for example. The mixing method of the raw materials is not particularly limited, but it is preferable to mix more uniformly. Among them, in the present invention, it is preferable to mix raw material compounds and the like by a mechanical milling method (for example, a ball mill method). By using the mechanical milling method, the raw materials can be pulverized and mixed at the same time, and the contact area of the raw material components can be increased. Further, the mechanical milling method in the present invention may be a mechanical milling method involving a synthesis reaction or a mechanical milling method not involving a synthesis reaction. As described above, the mechanical milling method involving a synthesis reaction is performed when the raw material compound is a mixture of a compound having a Li element and a compound having a PO ₄ skeleton (for example, the raw material compound is a Li source, an X source, a Y source, and In the case of a mixture of PO ₄ sources). On the other hand, the mechanical milling method without a synthesis reaction is used when the raw material compound is a compound having a Li element and a PO ₄ skeleton as described above (for example, when the raw material composition is Li ₃ PO ₄ ). be able to. Thereby, dispersibility, such as a raw material compound, can be improved. Incidentally, when the raw material compound is a compound having a Li element and PO ₄ backbone, using a general stirring means, simply it may be simply mixed. Moreover, when mixing using a ball mill method, a rotational speed is in the range of 100 rpm-11000 rpm, for example, and it is preferable that it exists in the range of 500 rpm-5000 rpm. Further, the treatment time is not particularly limited, and is preferably set as appropriate to obtain a desired raw material composition.

2. Synthesis Step Next, the synthesis step in the present invention will be described. In the synthesis step of the present invention, the raw material composition is baked to synthesize the raw material compound into a lithium nitride phosphate compound and polymerize the nitrogen-containing compound. It is a process to obtain.

  The firing temperature in the present invention is not particularly limited as long as it is usually a temperature at which the synthesis of the lithium nitride phosphate compound and the polymerization of the nitrogen-containing compound can be performed. In general, the lower limit of the firing temperature is preferably a temperature equal to or higher than the temperature at which the nitrogen-containing compound is decomposed or dissolved. A calcination temperature is 150 degreeC or more, for example, and it is preferable that it is 170 degreeC or more. On the other hand, the upper limit of the firing temperature is preferably a temperature equal to or lower than a temperature at which the nitrogen-containing compound polymer can be prevented from being excessively decomposed. A calcination temperature is 250 degrees C or less, for example, and it is preferable that it is 230 degrees C or less. Moreover, the baking time in this invention is 60 minutes or more, for example, 2 hours or more are preferable and 3 hours or more are more preferable. On the other hand, the firing time is, for example, 24 hours or less.

  The atmosphere during firing is not particularly limited, and examples thereof include air atmosphere; inert gas atmosphere such as nitrogen atmosphere and argon atmosphere; reducing atmosphere such as ammonia atmosphere and hydrogen atmosphere; vacuum and the like. Among these, an inert gas atmosphere, a reducing atmosphere, and a vacuum are preferable, and a reducing atmosphere is particularly preferable. This is because the oxidative deterioration of the lithium nitride phosphoric acid compound can be prevented. Moreover, as a baking method of a raw material composition, the method of using a baking furnace etc. can be mentioned, for example. By this step, for example, a cage-like lithium nitride phosphate compound-containing composition is obtained.

3. Next, the molding process in the present invention will be described. The forming step in the present invention is a step of forming the lithium nitride phosphate compound-containing composition into a sheet shape.

  In the present invention, the method for forming the lithium nitride phosphate compound-containing composition into a sheet is not particularly limited, and examples thereof include a pressing method, and the roll pressing method is particularly preferable. This is because the pressing can be performed continuously. In the present invention, it is preferable to carry out the pressing method when the lithium nitride phosphate compound-containing composition is heated and has a high flexibility. This is because the moldability is good. The thickness of the lithium nitride phosphate compound-containing sheet will be described in “B. Lithium nitride phosphate compound-containing sheet” described later. In the present invention, it is preferable to adjust the press pressure so that the thickness described later can be obtained.

4). Others The lithium nitride nitride compound-containing sheet obtained by the present invention is useful, for example, as a solid electrolyte layer forming sheet or a positive electrode active material layer forming sheet. Furthermore, the lithium nitride nitride compound-containing sheet can be used for, for example, a lithium battery. Therefore, in this invention, it can provide the manufacturing method of a lithium battery characterized by having the process of obtaining a nitrided lithium phosphate compound containing sheet | seat by performing the preparation process, synthetic | combination process, and shaping | molding process which were mentioned above. In this case, the lithium nitride phosphate compound-containing sheet may be a solid electrolyte layer forming sheet, a positive electrode active material layer forming sheet, or both. Furthermore, in this invention, the lithium nitride phosphoric acid compound containing sheet | seat characterized by having obtained by performing the preparation process mentioned above, a synthesis | combination process, and a shaping | molding process can be provided.

B. Next, the lithium nitride phosphate compound-containing sheet of the present invention will be described. The lithium nitride phosphate compound-containing sheet of the present invention is characterized by having a lithium nitride phosphate compound and a nitrogen-containing compound polymer obtained by polymerizing a nitrogen-containing compound.

  According to the present invention, since the lithium nitride phosphate compound and the nitrogen-containing compound polymer are complexed, a lithium nitride phosphate compound-containing sheet having excellent flexibility can be obtained. Furthermore, since the lithium nitride phosphate compound is excellent in Li ion conductivity, it has an advantage that it is excellent in Li ion conductivity.

  FIG. 2 is a schematic cross-sectional view showing an example of the lithium nitride phosphate compound-containing sheet of the present invention. The lithium nitride nitride compound-containing sheet 10 shown in FIG. 2 has a particulate lithium nitride phosphate compound 1 and a nitrogen-containing compound polymer 2 formed by polymerizing a nitrogen-containing compound. In the present invention, since the nitrogen-containing compound polymer 2 holds the lithium nitride phosphate compound 1, the lithium nitride phosphate compound-containing sheet 10 having excellent flexibility can be obtained.

The lithium nitride phosphate compound in the present invention is not particularly limited as long as it is obtained by nitriding the raw material compound described in the above-mentioned “A. Production method of lithium nitride phosphate compound-containing sheet”. As an example of the lithium nitride phosphate compound, a compound obtained by nitriding Li ₃ PO ₄ can be given. A sheet containing a compound obtained by nitriding Li ₃ PO ₄ is useful, for example, as a solid electrolyte layer forming sheet.

Another example of the lithium nitride phosphoric acid compound is a compound obtained by nitriding a compound having a NASICON (LISICON) type structure. A sheet containing this compound is useful, for example, as a sheet for forming a solid electrolyte layer. Among them, in the present invention, the lithium nitride lithium phosphate compound is Li _{a Xb} Y _{cP d} O _e N _f (X is at least selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al) Y is at least one selected from the group consisting of B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se, and a to f are 0.5 <a < 5.0, 0.5 ≦ b <3.0, 0 ≦ c <2.98, 0.02 <d ≦ 3.0, 2.0 <c + d <4.0, 3.0 <e ≦ 12. 0, 0.002 <f <2.0 is satisfied). This is because the Li ion conductivity is excellent.

In addition, as another example of the lithium nitride phosphate compound, a compound obtained by nitriding a compound having an olivine structure can be given. The sheet containing this compound is useful, for example, as a positive electrode active material layer forming sheet. Here, as an example of a compound obtained by nitriding a compound having an olivine structure, Li _{a Xb} Y _{cP d} O _e N _f (X is at least one selected from the group consisting of Mn, Fe, Co, and Ni) Y is at least one selected from the group consisting of Mg, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In and Zn, and a to f are 0.001 ≦ a ≦ 1.5, 0.7 ≦ b ≦ 1.3, 0 ≦ c ≦ 0.4, 0.7 ≦ b + c ≦ 1.3, 0.7 ≦ d ≦ 1.3, 3.0 ≦ e ≦ 5. 0, 0.002 ≦ f ≦ 2.0). This compound has the advantage of high Li ion conductivity and electronic conductivity. In particular, since this compound has high electron conductivity, the amount of conductive material used can be reduced compared to the conventional case, and the capacity of the battery can be increased.

As another example of a compound obtained by nitriding a compound having an olivine structure, Li _{a Xb} Y _{c Pd} O _e F _f N _g (X is selected from the group consisting of Mn, Fe, Co, and Ni) At least one, Y is at least one selected from the group consisting of Mg, Al, Ti, Ga, Cu, V, Nb, Zr, Ce, In and Zn, and a to g are 0.001. ≦ a ≦ 1.5, 0.7 ≦ b ≦ 1.3, 0 ≦ c ≦ 0.4, 0.7 ≦ b + c ≦ 1.3, 0.7 ≦ d ≦ 1.3, 3.0 ≦ e ≦ 5.0, 0.002 ≦ f ≦ 2.0, 0.002 ≦ g ≦ 2.0). This compound has the advantage of high Li ion conductivity and electronic conductivity. Furthermore, since it has F in the composition, it can be made excellent in Li ion conductivity, electron conductivity, and durability.

  In the present invention, the lithium nitride lithium phosphate compound is preferably in the form of particles (powder). This is because peeling and cracking do not occur unlike the film-like lithium nitride phosphate compound, and the durability is excellent. The average particle size of the particulate lithium nitride phosphate compound is, for example, preferably 0.1 μm or more, and more preferably in the range of 0.1 μm to 100 μm. The average particle size can be calculated by a laser particle size distribution meter.

  Moreover, it is preferable that the lithium nitride phosphoric acid compound in the present invention is not a material in which N is simply adsorbed on the raw material compound, but is present in the lithium nitride phosphoric acid compound in a state where N is chemically bonded.

  The ratio of the lithium nitride phosphate-containing material contained in the lithium nitride phosphate compound-containing sheet varies depending on the use of the lithium nitride phosphate compound-containing sheet. Generally, when the proportion of the lithium nitride phosphate-containing material is too small, the Li ion conductivity tends to be low, and when the proportion of the lithium nitride phosphate-containing material is too large, the flexibility tends to be low. . For example, when the lithium nitride phosphate compound-containing sheet is used as a sheet for forming a solid electrolyte layer, the proportion of the lithium nitride phosphate-containing material is preferably in the range of 10% by volume to 90% by volume, for example. On the other hand, when the lithium nitride phosphate compound-containing sheet is used as a positive electrode active material layer forming sheet, the ratio of the lithium nitride phosphate-containing material is preferably in the range of 10% by volume to 90% by volume, for example.

  The ratio of the nitrogen-containing compound polymer contained in the lithium nitride phosphate compound-containing sheet is preferably such an amount as to fill the gaps in the obtained lithium nitride phosphate, and specifically, for example, in the range of 5% to 30% by volume. Preferably, it is within the range of 5% by volume to 10% by volume. If the proportion of the nitrogen-containing compound polymer is too small, the desired flexibility may not be obtained, and if the proportion of the nitrogen-containing compound polymer is too large, the Li ion conductivity may be lowered. It is.

  In addition, the thickness of the lithium nitride phosphate compound-containing sheet is not particularly limited, and is preferably selected as appropriate according to the use of the sheet. For example, when the lithium nitride phosphate compound-containing sheet is used as a solid electrolyte layer forming sheet or a positive electrode active material layer, the thickness of the sheet is, for example, in the range of 0.1 μm to 1000 μm, and 0.1 μm to 300 μm. It is preferable to be within the range.

  In the present invention, it is possible to provide a lithium battery using a sheet containing a lithium nitride phosphate compound. In this case, the lithium nitride phosphate compound-containing sheet may be a solid electrolyte layer forming sheet, a positive electrode active material layer forming sheet, or both. Moreover, you may use the sheet | seat for positive electrode active material layer formation for the lithium battery which has electrolyte solution.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
Li ₃ PO ₄ (manufactured by Aldrich), urea (manufactured by Aldrich) and calcium hydroxide (manufactured by Aldrich) were prepared as raw materials. Next, 1 g (about 8.6 mmol) of Li ₃ PO ₄ , 2 g (about 33 mmol) of urea, 0.1 g of calcium hydroxide and 0.1 g of pure water are weighed and mixed in a mortar, and the raw material composition Got. Thereafter, the obtained raw material composition was put in a glass tube and evacuated. Next, the glass tube was baked at 200 ° C. for 5 hours in a tubular furnace to obtain a lithium nitride phosphate-containing composition. The obtained lithium nitride nitride-containing composition was bowl-shaped. Finally, the lithium nitride phosphate-containing composition was formed into a sheet by a roll press to obtain a lithium nitride phosphate-containing sheet.

[Example 2]
As raw materials, Li ₃ PO ₄ (manufactured by Aldrich), urea (manufactured by Aldrich), lithium hydroxide (manufactured by Aldrich) and formaldehyde (manufactured by Aldrich) were prepared. Next, 1 g (about 8.6 mmol) of Li ₃ PO ₄ , 2 g (about 33 mmol) of urea, 0.1 g of lithium hydroxide and 0.1 g of pure water were weighed and mixed in a mortar. The obtained mixture was put into a glass boat, and 0.01 g (about 0.3 mmol) of formaldehyde was put into another glass boat. Then, two glass boats were put into a glass tube and evacuated. Next, the glass tube was baked at 200 ° C. for 5 hours in a tubular furnace to obtain a lithium nitride phosphate-containing composition. The obtained lithium nitride nitride-containing composition was bowl-shaped. Finally, the lithium nitride phosphate-containing composition was formed into a sheet by a roll press to obtain a lithium nitride phosphate-containing sheet.

[Reference Example 1]
In Reference Example 1, nitridation using urea was performed on Li ₃ PO ₄ . In this reference example, no strong alkali compound was used, and no urea polymerization was performed. First, Li ₃ PO ₄ (manufactured by Aldrich) and urea (manufactured by Aldrich) were prepared as raw materials. Next, 1 g each of Li ₃ PO ₄ and urea was weighed and mixed in a mortar to obtain a raw material composition. Thereafter, the obtained raw material composition was molded into 1 cmφ × 2 mmt with a molding machine, and the obtained molded body was put into a glass tube and evacuated. Next, the glass tube was baked in a tube furnace at 300 ° C. for 3 hours. Thereby, a lithium nitride phosphate compound (LIPON) was obtained.

The chemical bonding state of the obtained lithium nitride nitride compound was evaluated using photoelectron spectroscopy (XPS method). As a result, peaks of O—N═O unit, NP3 unit, and P—N = P unit were confirmed. Since these peaks are the same as the peaks of LIPON formed by the conventional high-frequency magnetron sputtering method, it was confirmed that nitriding of Li ₃ PO ₄ occurred.

The obtained lithium nitride phosphate compound was evaluated for crystal structure using an X-ray diffraction (XRD) method. As a result of the analysis, it was found that the obtained lithium nitride lithium phosphate compound was estimated to have O ₃ P—N—PO ₃ units. This suggested that the nitrogen element of the nitrogen-containing compound was not simply adsorbed on the surface of Li ₃ PO ₄ but was incorporated in the chemical bond. Furthermore, it was 50 * 10 < ^-8 > (S / cm) when the ionic conductivity of the obtained lithium nitride phosphoric acid compound was measured by the impedance analysis method.
[Comparative Reference Example 1]
Li ₃ PO ₄ (manufactured by Aldrich) and urea (manufactured by Aldrich) were prepared as raw materials. Next, 1 g each of Li ₃ PO ₄ and urea was weighed and mixed in a mortar to obtain a composition for evaluation. It was 7 * 10 < ^-8 > (S / cm) when the ionic conductivity of the obtained lithium nitride phosphoric acid compound was measured by the impedance analysis method. From the results of Reference Example 1 and Comparative Reference Example 1, it was confirmed that by using urea, Li ₃ PO ₄ was nitrided and Li ion conductivity was improved.

[Reference Example 2]
In Reference Example 2, nitridation using urea was performed on Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ . In this reference example, no strong alkali compound was used, and no urea polymerization was performed. First, Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ was synthesized as a raw material. This compound was synthesized by the method described in H. Aono et al., “Ionic-Conductivity of Solid Electrolytes Based on Lithium Titanium Phosphate”, J. Electrochem. Soc., 137 (1990) 1023. Next, 1 g each of Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ and urea (manufactured by Aldrich) were weighed and mixed in a mortar to obtain a raw material composition. Thereafter, the obtained raw material composition was molded into 1 cmφ × 2 mmt with a molding machine, and the obtained molded body was put into a glass tube and evacuated. Next, the glass tube was fired at 500 ° C. for 3 hours in a tubular furnace. As a result, a lithium nitride phosphate compound was obtained.

The chemical bonding state of the obtained lithium nitride nitride compound was evaluated using photoelectron spectroscopy (XPS method). As a result, peaks of O—N═O unit, NP3 unit, and P—N = P unit were confirmed. From this, it was confirmed that nitridation of Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ occurred. Furthermore, it was 6620 * 10 < ^-8 > (S / cm) when the ionic conductivity of the obtained lithium nitride phosphoric acid compound was measured by the impedance analysis method.

[Comparative Reference Example 2]
Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ used in Reference Example 2 was used as the evaluation composition. It was 3389 * 10 < ^-8 > (S / cm) when the ionic conductivity of the obtained lithium nitride phosphoric acid compound was measured by the impedance analysis method. From the results of Reference Example 2 and Comparative Reference Example 2, it was confirmed that by using urea, Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ was nitrided and Li ion conductivity was improved. It was done.

[Reference Example 3]
In Reference Example 3, nitridation using urea was performed on LiFePO ₄ . In this reference example, no strong alkali compound was used, and no urea polymerization was performed. First, LiFePO ₄ and urea (manufactured by Aldrich) were prepared as raw materials. Next, 1 g each of LiFePO ₄ and urea were weighed and mixed in a mortar to obtain a raw material composition. Thereafter, the obtained raw material composition was molded into 1 cmφ × 2 mmt with a molding machine, and the obtained molded body was put into a glass tube and evacuated. Next, the glass tube was fired at 500 ° C. for 3 hours in a tubular furnace. As a result, a lithium nitride phosphate compound was obtained. The color of the obtained lithium nitride nitride compound was brown.

[Comparative Reference Example 3]
LiFePO ₄ was molded into 1 cmφ × 2 mmt by a molding machine and baked under conditions of 750 ° C. and 24 hours in an Ar atmosphere to obtain a composition for evaluation. The color of the evaluation composition was light gray.

[Reference Example 4]
In Reference Example 4, nitridation using urea was performed on LiFePO ₄ into which F was introduced. In this reference example, no strong alkali compound was used, and no urea polymerization was performed. First, 0.24 g of Li ₂ CO ₃ , 0.34 g of LiF, 2.34 g of FeC ₂ O ₄ and 1.72 g of (NH ₄ ) ₂ HPO ₄ were mixed, and 25 g of ethanol was further added. The obtained composition was ball milled under conditions of 4000 rpm for 3 hours, and then ethanol was evaporated to obtain a raw material compound having an olivine structure (LiFePO ₄ into which F was introduced). A lithium nitride lithium phosphate compound was obtained in the same manner as in Reference Example 3, except that the obtained raw material compound was used. The color of the obtained lithium nitride nitride compound was dark brown.

[Evaluation of Reference Examples 3 and 4 and Comparative Reference Example 3]
XRD measurement was performed using the lithium nitride phosphate compound of Reference Examples 3 and 4 and the composition for evaluation of Comparative Example Reference Example 3. As a result, it was confirmed that Reference Example 3 showed an equivalent peak to Comparative Reference Example 3, and that the main peak near 35.7 ° was shifted. Furthermore, since the color of the sample changed clearly, it is considered that in Reference Example 3, N could be introduced into the iron olivine structure without impurities. It was confirmed that Reference Example 4 showed an equivalent peak to Comparative Reference Example 3 and that the main peak near 35.7 ° was shifted. Furthermore, since the color of the sample changed clearly, it is considered that in Reference Example 4, N and F could be introduced into the iron olivine structure without impurities.

Furthermore, electron conductivity measurement was performed using the lithium nitride phosphate compound of Reference Examples 3 and 4 and the composition for evaluation of Comparative Reference Example 3. As a result, the LiFePO ₄ obtained by introducing a N (Reference Example 3), was 1.3 × ¹⁰ -2 S / cm, the N, LiFePO ₄ was introduced F (Reference Example 4), 2.1 × 10 ^{- 2} S / cm and 0.83 × 10 ⁻² S / cm for LiFePO ₄ (Comparative Reference Example 3). Thereby, it was confirmed that the electron conductivity was improved by introducing N, and the electron conductivity was further improved by introducing N and F.

DESCRIPTION OF SYMBOLS 1 ... Lithium nitride phosphate compound 2 ... Nitrogen-containing compound polymer 3 ... Lithium nitride phosphate compound-containing sheet

Claims (12)

A preparation step of preparing a raw material composition containing a raw material compound having an Li element and a PO ₄ skeleton, nitriding the raw material compound and having a polymerizable nitrogen-containing compound, and a strong alkali compound;
By baking the raw material composition, synthesis from the raw material compound to a lithium nitride phosphate compound and polymerization of the nitrogen-containing compound to obtain a lithium nitride phosphate compound-containing composition;
A molding step of molding the lithium nitride phosphate compound-containing composition into a sheet;
A method for producing a sheet containing lithium nitride phosphate compound, comprising: The starting compound, method of manufacturing the nitride lithium phosphate compound-containing sheet according to claim 1, characterized in that the Li ₃ PO _4.   2. The method for producing a lithium nitride nitride compound-containing sheet according to claim 1, wherein the raw material compound is a compound having a NASICON (LISICON) type structure.   The method for producing a lithium nitride nitride compound-containing sheet according to claim 1, wherein the raw material compound is a compound having an olivine structure.   The said nitrogen-containing compound has at least 2 amino group, The manufacturing method of the lithium nitride phosphate compound containing sheet | seat of any one of Claim 1 to 4 characterized by the above-mentioned.   The said nitrogen-containing compound is urea, The manufacturing method of the lithium nitride phosphoric acid compound containing sheet | seat of any one of Claim 1-5 characterized by the above-mentioned.   The said strong alkali compound is calcium hydroxide or lithium hydroxide, The manufacturing method of the lithium nitride phosphoric acid compound containing sheet | seat of any one of Claim 1-6 characterized by the above-mentioned.   The lithium nitride phosphate compound-containing sheet according to any one of claims 1 to 7, wherein the raw material composition contains a polymerizable compound other than the nitrogen-containing compound. Production method.   9. The method for producing a lithium nitride phosphonate compound-containing sheet according to claim 8, wherein the polymerizable compound other than the nitrogen-containing compound is formaldehyde.   10. The method for producing a lithium nitride nitride compound-containing sheet according to claim 1, wherein a firing temperature in the synthesis step is in a range of 150 ° C. to 250 ° C. 10. .   A lithium nitride phosphate compound-containing sheet comprising: a lithium nitride phosphate compound; and a nitrogen-containing compound polymer obtained by polymerizing a nitrogen-containing compound.   The ratio of the said nitrogen containing compound polymer exists in the range of 5 volume%-30 volume%, The lithium nitride nitride compound containing sheet | seat of Claim 11 characterized by the above-mentioned.

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