WO2010041598A1 - Method for producing lithium phosphorus oxynitride compound - Google Patents

Abstract

A method for producing a lithium phosphorus oxynitride compound, wherein a lithium phosphorus oxynitride compound can be obtained by simple processes. The method for producing a lithium phosphorus oxynitride compound is characterized by having a preparation step wherein a raw material composition which contains a raw material compound containing Li element and a PO₄ skeleton, and a nitriding agent represented by general formula (1) is prepared, and a synthesis step wherein a lithium phosphorus oxynitride compound is synthesized by firing the raw material composition. In general formula (1), R₁, R₂ and R₃ each independently represents a functional group having at least one of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N).

Description

Method for producing lithium nitride phosphate compound

The present invention relates to a method for producing a lithium nitride phosphoric acid compound capable of obtaining, for example, a lithium nitride lithium phosphate compound useful as a solid electrolyte or an active material by a simple method.

In recent years, with the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras and mobile phones, development of batteries 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.

For example, an oxide solid electrolyte is known as such a solid electrolyte, 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 Literature 1 and Patent Literature 2 disclose a method of forming a lithium nitride lithium phosphate thin film by resistance heating vapor deposition. Further, in Patent Document 3, a lithium nitride phosphate thin film containing a transition metal element is formed by using lithium orthophosphate (Li ₃ PO ₄ ) and a transition metal element (for example, Ti) as a target and using nitrogen as a sputtering gas. A method is disclosed. However, these methods have a problem that the amount that can be synthesized per unit time is extremely small and the mass productivity is poor.

In Patent Document 4, a method of forming an oxynitride by heating a mixture of an oxide having photocatalytic activity (eg, titanium oxide) and a nitrogen compound (eg, urea) adsorbed on the oxide at room temperature. Is disclosed. In Patent Document 5, Li _x M _1-y M ′ _y (XO ₄ ) _n (M is a transition metal, M ′ is Mg ²⁺ , Ca ²⁺ , Al ³⁺ , Zn ^2+, etc., and X is S, P, and Si) are disclosed, and further, a method of reducing the raw materials of the above compounds in an NH ₃ / H ₂ O atmosphere is disclosed. Patent Document 6 discloses that Li _3.0 P _0.8 Si _0.1 Ge _0.1 O _3.45 N _0.8 and Li _2.7 P _0.8 Ge _0.1 B as solid electrolytes. _{0.1 O 3.45 N 0.8, Li 3.0} P 0.8 B 0.1 Al 0.1 O 3.45 N 0.8 , etc. are disclosed. Further, Patent Document 7 discloses a non-aqueous electrolyte secondary battery represented by Li _x MePO _4-x N _y (Me is at least one atom selected from the group consisting of Fe, Co, Ni, and Mn). An active material is disclosed. In this technique, a phosphate compound is heated in a nitrogen gas atmosphere and reacted with ammonia gas to synthesize an active material composed of a phosphate compound containing nitrogen. Specifically, LiFePON and LiCoPOFN are disclosed.

In Patent Document 8, a raw material of a material represented by Li ₂ MePO ₄ F (Me is at least one transition metal element selected from the group consisting of Fe, Co, Mn, and Ni) is mixed and obtained. A method for producing an active material for a non-aqueous electrolyte battery that melts the obtained mixture is disclosed. Patent Document 9 discloses an olivine-type lithium iron phosphate positive electrode material and a method for producing the same. Patent Document 10 discloses a part of olivine-type lithium phosphate represented by LiMPO ₄ (M is composed of at least one element selected from Co, Ni, Mn, and Fe) as a positive electrode active material. The use of those substituted with fluorine is disclosed. Patent Document 11 discloses that after forming an amorphous LIPON, a part thereof is crystallized to form a solid electrolyte layer containing crystal grains.

JP 2004-183078 A JP 2004-228029 A JP 2004-193112 A JP 2002-154823 A Special table 2004-509058 gazette JP 2005-038843 A JP 2005-353320 A JP 2007-073360 A JP 2006-131485 A JP 2003-187799 A JP 2005-93372 A

The present invention has been made in view of the above-mentioned problems, and has as its main object to provide a method for producing a lithium nitride phosphate compound capable of obtaining a lithium nitride phosphate compound by a simple method.

In order to achieve the above object, in the present invention, a preparation step of preparing a raw material composition containing a raw material compound having an Li element and a PO ₄ skeleton and a nitriding agent represented by the following general formula (1) And a synthesis step of synthesizing the lithium nitride phosphate compound by firing the raw material composition and providing a method for producing the lithium nitride phosphate compound.

In the general formula (1), R ₁ , R ₂ and R ₃ are each independently a functional group having at least one of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). is there.

According to the present invention, by using a raw material composition containing a nitriding agent and firing the raw material composition, a lithium nitride phosphate compound can be easily obtained. Further, the conventional sputtering method and vapor deposition method have a problem that the amount that can be synthesized per unit time is extremely small, and the mass productivity is low. On the other hand, the present invention has an advantage that such a problem can be solved.

In the above invention, the starting compound is preferably a _Li 3 PO _4. This is because by using a raw material compound having both the Li element and the PO ₄ skeleton, a lithium nitride phosphate compound can be obtained more easily.

In the above invention, the starting compound is preferably a mixture of _Li 2 CO ₃ and _{(NH 4) H 2 PO 4} . This is because it is easy to adjust the ratio of the Li element and the PO ₄ skeleton. Further, since CO ₂ is generated from Li ₂ CO ₃ and NH ₃ and H ₂ are generated from (NH ₄ ) H ₂ PO ₄ by firing, the composition of the target lithium nitride phosphate compound is hardly adversely affected. Has the advantage.

In the above invention, the raw material compound is Li _{a Xb} Y _c P _d O _e (X is at least one selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al, and 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) It is preferable that it is a compound represented by these. This is because a lithium nitride phosphate compound having high Li ion conductivity can be obtained.

In the above invention, the raw material compound is Li _{a Xb} Y _c P _d O _e (X is at least one selected from the group consisting of Mn, Fe, Co and Ni, and Y is Mg, Al, Ti , Ga, Cu, V, Nb, Zr, Ce, In, and Zn, 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, and 3.0 ≦ e ≦ 5.0. A compound is preferred. This is because a lithium nitride lithium phosphate compound having high Li ion conductivity and electron conductivity can be obtained.

In the above invention, the raw material compound is 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 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 ≦ The compound represented by (2) satisfying the relationship of 2.0 is preferable. This is because a lithium nitride lithium phosphate compound having high Li ion conductivity and electron conductivity can be obtained.

In the above invention, before the preparation step, Li source, X source, Y source, using a mixture containing PO ₄ source and F sources, it is preferable to have a synthesis step of synthesizing the starting compound. This is because it is possible to obtain a lithium nitride lithium phosphate compound having more excellent durability.

In the above invention, the nitriding agent is preferably solid or liquid at normal temperature (25 ° C.). This is because nitriding can be performed efficiently.

In the above invention, the nitriding agent is preferably urea. This is because nitriding can be performed effectively.

In the above invention, the firing temperature in the synthesis step is preferably in the range of 100 ° C to 800 ° C. This is because a lithium nitride phosphate compound having high Li ion conductivity can be obtained.

In the above invention, the firing time in the synthesis step is preferably in the range of 10 minutes to 7 hours. This is because a lithium nitride phosphate compound having high Li ion conductivity can be obtained.

In the present invention, Li _{a Xb} Y _{cP d} O _e N _f (X is at least one selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al, and 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 <Satisfaction of 2.0) is provided. A lithium nitride lithium phosphate compound is provided.

According to the present invention, since it has the above composition, it can be a lithium phosphate lithium compound having high Li ion conductivity. This lithium nitride phosphate compound is usually a compound having a NASICON (LISICON) type structure.

In the present invention, 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, and Y is Mg, Al, Ti, It is at least one selected from the group consisting of 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 The lithium nitride phosphate compound is characterized in that it is represented by the following formula:

According to the present invention, since it has the above composition, it can be a lithium nitride lithium phosphate compound having high Li ion conductivity and electron conductivity because it has the above composition. This lithium nitride phosphate compound is usually a compound having an olivine structure.

In the present invention, Li _{a Xb} Y _{cP d} O _e F _f N _g (X is at least one selected from the group consisting of Mn, Fe, Co and Ni, and Y is Mg, Al, It is at least one selected from the group consisting of 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, 0.002 ≦ g ≦ 2.0). A lithium nitride phosphate compound is provided.

According to the present invention, since it has the above composition, it can be a lithium nitride lithium phosphate compound having high Li ion conductivity and electron conductivity. Furthermore, since it has F in the composition, it can be a lithium nitride phosphate compound excellent in Li ion conductivity, electron conductivity, and durability. This lithium nitride phosphate compound is usually a compound having an olivine structure.

In the above invention, the lithium nitride lithium phosphate compound is preferably in the form of particles. This is because peeling and cracking do not occur and the durability is excellent as compared with a thin film lithium nitride phosphate compound.

In the above invention, the average particle size of the lithium nitride lithium phosphate compound is preferably in the range of 100 nm to 100 μm. This is because it is useful as a solid electrolyte or a positive electrode active material.

In the above invention, the specific surface area of the lithium nitride lithium phosphate compound is preferably in the range of 0.1 m ² / g to 300 m ² / g. This is because a lithium nitride phosphate compound having high Li ion conductivity can be obtained.

The present invention also provides a solid electrolyte layer characterized by containing a compound having the above-mentioned NASICON (LISICON) type structure.

According to the present invention, a solid electrolyte layer having excellent Li ion conductivity can be obtained by using the above compound.

The present invention also provides a positive electrode active material layer comprising the compound having the olivine structure described above.

According to the present invention, a positive electrode active material layer having excellent electron conductivity can be obtained by using the above compound.

In the present invention, there is an effect that a lithium nitride phosphate compound can be obtained by a simple method.

It is explanatory drawing which shows an example of the manufacturing method of the lithium nitride phosphate compound of this invention. It is explanatory drawing which shows the other example of the manufacturing method of the lithium nitride phosphate compound of this invention. 7 shows the results of XPS measurement on the lithium nitride nitride compound of Example 1-1 and Comparative Example 1-1 and the evaluation composition of Comparative Example 1-2. It is a result of the XRD measurement with respect to the lithium nitride nitride compound of Example 1-1. 3 is a result of XPS measurement for a lithium nitride lithium phosphate compound of Example 2. It is a result of the XRD measurement with respect to the lithium nitride phosphate compound of Example 3 and Comparative Example 3. It is a result of the XRD measurement with respect to the lithium nitride phosphate compound of Example 4 and Comparative Example 3.

Hereinafter, a method for producing a lithium nitride phosphate compound, a lithium nitride phosphate compound, a solid electrolyte layer, and a positive electrode active material layer of the present invention will be described in detail.

A. First, the method for producing the lithium nitride phosphate compound of the present invention will be described. The method for producing a lithium nitride lithium phosphate compound of the present invention is a preparation for preparing a raw material composition containing a raw material compound having an Li element and a PO ₄ skeleton and the nitriding agent represented by the general formula (1) described above. It has a process and the synthetic | combination process which bakes the said raw material composition and synthesize | combines a lithium nitride phosphoric acid compound, It is characterized by the above-mentioned.

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 raw material composition containing a nitriding agent and firing the raw material composition, a lithium nitride phosphate compound can be easily obtained. Further, the conventional sputtering method and vapor deposition method have a problem that the amount that can be synthesized per unit time is extremely small, and the mass productivity is low. On the other hand, the present invention has an advantage that such a problem can be solved.

In addition, for example, by using Li ₃ N as a nitriding agent and performing a baking treatment at a temperature of about 800 ° C., there is a possibility that a lithium nitride phosphoric acid compound can be synthesized. However, Li ₃ N is likely to react with moisture, and it is expected that it will be difficult to control the reaction. On the other hand, since the nitriding agent used in the present invention is usually a less reactive material than Li ₃ N, the lithium nitride phosphoric acid compound can be obtained more safely.

FIG. 1 is an explanatory diagram showing an example of a method for producing a lithium nitride lithium phosphate compound 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, and urea is prepared as a nitriding agent. Next, these are mixed by a ball mill or the like to prepare a raw material composition (preparation step). Thereafter, the obtained raw material composition is baked, for example, in a vacuum state at 500 ° C. to obtain a lithium nitride lithium phosphate compound (synthesis process).

FIG. 2 is an explanatory view showing another example of the method for producing a lithium nitride lithium phosphate compound of the present invention. In FIG. 2, a mixture of lithium carbonate (Li ₂ CO ₃ ) and diammonium hydrogen phosphate ((NH ₄ ) H ₂ PO ₄ ) is prepared as a raw material compound having an Li element and a PO ₄ skeleton, and is used as a nitriding agent. Prepare urea. Next, these are mixed by a ball mill or the like to prepare a raw material composition (preparation step). Thereafter, the obtained raw material composition is baked, for example, in a vacuum state at 500 ° C. to obtain a lithium nitride lithium phosphate compound (synthesis process).
Hereafter, the manufacturing method of the lithium oxynitride compound of this invention is demonstrated for every process.

1. Preparation Step The preparation step in the present invention is a step of preparing a raw material composition containing a raw material compound having an Li element and a PO ₄ skeleton and the nitriding agent described above.

(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. 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, carbonic acid compounds, nitric acid compounds, chlorides, sulfuric acid compounds, and fluorides. 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). 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. Preferably, the amount is within the range of 30 to 60 parts by mole.

(2) Nitriding agent Next, the nitriding agent in the present invention will be described. The nitriding agent in the present invention is represented by the following general formula (1).

In the general formula (1), R ₁ , R ₂ and R ₃ are each independently a functional group having at least one of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). is there. In the general formula (1), R ₁ , R ₂ and R ₃ may all be the same or different from each other, and _{two of} R ₁ , R ₂ and R ₃ may be the same. . Moreover, it is preferable that at least one of R ₁ , R ₂ and R ₃ has carbon (C).

Further, the nitriding agent in the present invention may be any of solid, liquid, and gas at normal temperature (25 ° C.), but among them, it is preferable that the nitriding agent is solid or liquid. This is because a raw material composition in which the nitriding agent and the raw material compound are in physical contact efficiently can be produced, and the nitriding efficiency of the raw material composition is improved. It should be noted that particularly when ammonia is used as a nitriding agent, the nitriding reaction hardly occurs, the corrosiveness is high, and the equipment may be expensive.

Examples of the nitriding agent in the present invention include urea, methylamine, ethylamine, diethylamine, triethylamine, aminoethane, aniline, nicotine, cyclohexylamine, ammonia and the like, and urea is particularly preferable. This is because it is difficult to adversely affect the composition of the target lithium nitride phosphate compound. Urea is a compound in which R ₁ and R ₂ are H and R ₃ is —CONH ₂ in the general formula (1).

The addition amount of the nitriding agent is preferably selected as appropriate according to the composition of the target lithium nitride phosphate compound. When Li in the raw material compound is 100 mole parts, N in the nitriding agent is preferably in the range of, for example, 10 mole parts to 100 mole parts, and more preferably in the range of 30 mole parts to 60 mole parts. preferable. In particular, when Li ₃ PO ₄ is used as the raw material compound and urea is used as the nitriding agent, when Li ₃ PO ₄ is 100 parts by weight, the urea is preferably 100 parts by weight or more, and 150 parts by weight or more. More preferably, it is more preferably 200 parts by weight or more. On the other hand, urea is preferably 1000 parts by weight or less. In the present invention, it is important that Li ₃ PO ₄ and urea are sufficiently in contact before firing. Therefore, when the proportion of urea is too large, sufficient nitridation does not occur in the portion that is not in contact with Li ₃ PO ₄ , so that the overall nitridation efficiency may deteriorate.

(3) Preparation of raw material composition The raw material composition in this invention contains the raw material compound and nitriding agent which were mentioned above. Examples of the method for adjusting the raw material composition include a method of mixing a raw material compound and a nitriding agent. The mixing method of the raw materials is not particularly limited, but it is preferable to mix more uniformly. Among these, in the present invention, it is preferable to mix the raw material compound and the nitriding agent 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, the dispersibility of a raw material compound and a nitriding agent 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. When mixing is performed using the ball mill method, the rotational speed is, for example, in the range of 100 rpm to 11000 rpm, and preferably in the range of 500 rpm to 5000 rpm. Further, the treatment time is not particularly limited, and is preferably set as appropriate to obtain a desired raw material composition.

In the present invention, the raw material composition may be prepared by vaporizing the nitriding agent and disposing the raw material compound in the atmosphere. In this state, by firing the raw material composition, it is possible to synthesize a desired lithium nitride phosphate compound.

2. Synthesis Step Next, the synthesis step in the present invention will be described. The synthesis step in the present invention is a step of baking the raw material composition to synthesize a lithium nitride phosphate compound.

The firing temperature in the present invention is not particularly limited as long as it is a temperature at which a desired lithium nitride phosphoric acid compound can be obtained, but is preferably a temperature equal to or higher than the temperature at which the nitriding agent decomposes or dissolves. This is because it becomes easy to obtain a lithium nitride lithium phosphate compound in which a nitrogen element is incorporated into a chemical bond. The firing temperature is preferably appropriately selected according to the type of nitriding agent used, and is, for example, 100 ° C. or higher, preferably 300 ° C. or higher, more preferably 400 ° C. or higher, and further preferably 500 ° C. or higher. On the other hand, a calcination temperature is 800 degrees C or less, for example, and 700 degrees C or less is more preferable. The firing time is, for example, 10 minutes or longer, preferably 30 minutes or longer, and more preferably 1 hour or longer. On the other hand, baking time is 7 hours or less, for example, and 5 hours or less are more preferable.

The atmosphere during firing is not particularly limited, and examples thereof include an air atmosphere; an inert gas atmosphere such as a nitrogen atmosphere and an argon atmosphere; a reducing atmosphere such as an ammonia atmosphere and a hydrogen atmosphere; a 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.

3. Others The lithium nitride phosphate compound obtained by the method for producing a lithium nitride phosphate compound of the present invention is useful, for example, as a solid electrolyte or a positive electrode active material. Furthermore, this solid electrolyte can be used for a solid electrolyte membrane (solid electrolyte layer) of a lithium battery, for example. Therefore, in the present invention, there is provided a lithium battery characterized by comprising a step of obtaining a solid electrolyte by performing the preparation step and the synthesis step described above, and a step of forming a solid electrolyte layer using the solid electrolyte. A method can be provided. Moreover, in this invention, the solid electrolyte characterized by the above-mentioned manufacturing method can be provided. Furthermore, in the present invention, it is possible to provide an all-solid-state lithium battery characterized by having a solid electrolyte layer using the solid electrolyte obtained by the above production method. On the other hand, the positive electrode active material obtained by this invention can be used for the positive electrode active material layer of a lithium battery. Therefore, in the present invention, lithium having a step of obtaining a positive electrode active material by performing the preparation step and the synthesis step described above, and a step of forming a positive electrode active material layer using the positive electrode active material A method for manufacturing a battery can be provided. Moreover, in this invention, the positive electrode active material characterized by obtained by said manufacturing method can be provided. Furthermore, in the present invention, it is possible to provide an all-solid-state lithium battery characterized by having a positive electrode active material layer containing the positive electrode active material obtained by the above production method.

B. Next, the lithium nitride phosphate compound of the present invention will be described. The lithium nitride phosphate compound of the present invention can be roughly divided into three embodiments.

1. First Embodiment A first embodiment of the lithium nitride nitride compound of the present invention is Li _{a Xb} Y _{cP d} O _e N _f (where X is a 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 and 0.002 <f <2.0 are satisfied). Note that 0.02 <f <2.0 is preferable.

According to the first embodiment, since it has the above composition, it can be a lithium phosphate lithium compound having high Li ion conductivity. This lithium nitride phosphate compound is usually a compound having a NASICON (LISICON) type structure. Note that the lithium nitride phosphate compound of the first embodiment is not a material in which N is simply adsorbed to Li _{a Xb} Y _c P _d O _e , but in a state where N is chemically bonded, the lithium nitride phosphate compound (Li _a it is present in _{X b Y c P d O e} N f) within.

In the present invention, the lithium nitride phosphoric acid compound of the first embodiment is preferably in the form of particles (powder). This is because peeling and cracks do not occur unlike the thin film lithium nitride phosphate compound, and the durability is excellent. The average particle diameter of the particulate lithium nitride phosphate compound is, for example, 100 nm or more, preferably 2 μm or more, and particularly preferably 4 μm or more. On the other hand, the average particle diameter is, for example, preferably 100 μm or less, more preferably 20 μm or less. The average particle diameter can be calculated with a laser diffraction particle size distribution meter.

Further, the specific surface area of the lithium nitride lithium phosphate compound is, for example, preferably 0.1 m ² / g or more, more preferably 0.5 m ² / g or more. On the other hand, the specific surface area is, for example, 300 m ² / g or less, preferably 100 m ² / g or less. The specific surface area can be calculated by the BET method (gas adsorption method). In addition, when the thin film using the conventional sputtering method or vapor deposition method is shaved, a particulate lithium nitride phosphate compound may be obtained in the same manner as described above. However, since such particles are formed from a thin film with few irregularities, the specific surface area of the particles becomes small. In contrast, the lithium nitride phosphate compound obtained by the method described in “A. Method for producing lithium nitride phosphate compound” has irregularities on the surface of the particles, and therefore has a large specific surface area.

Examples of the use of the lithium nitride phosphoric acid compound of the first embodiment include a solid electrolyte. When a lithium nitride lithium phosphate compound is used as a solid electrolyte, the powdered lithium nitride phosphate compound can be formed into a pellet and used, for example, as a solid electrolyte layer of an all solid lithium battery. Moreover, you may use lithium nitride phosphoric acid compound as a solid electrolyte material added to the positive electrode layer (positive electrode active material layer) or negative electrode layer (negative electrode active material layer) of an all-solid-state lithium battery. Further, the surface of the electrode active material of a general lithium battery (for example, a non-aqueous electrolyte type lithium battery) is not limited to the all solid-state lithium battery, and may be used by being coated with a lithium nitride phosphate compound.

The lithium nitride phosphate compound of the first embodiment can be obtained, for example, by the method described in “A. Method for producing lithium nitride phosphate compound” above.

2. Second Embodiment A second embodiment of the lithium nitride phosphoric acid compound of the present invention is 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, 0.002 ≦ f ≦ 2.0).

According to the second embodiment, since it has the above composition, it can be a lithium nitride lithium phosphate compound having high Li ion conductivity and high electron conductivity. This lithium nitride phosphate compound is usually a compound having an olivine structure. In addition, the lithium nitride phosphate compound of the second embodiment is not a material in which N is simply adsorbed to Li _{a Xb} Y _c P _d O _e , but in a state in which N is chemically bonded, the lithium nitride phosphate compound (Li _a it is present in _{X b Y c P d O e} N f) within. Moreover, in this invention, it is preferable that the lithium nitride phosphoric acid compound of 2nd embodiment is a particulate form (powder form). About an average particle diameter etc., it is the same as that of the content mentioned above.

Examples of the use of the lithium nitride nitride compound of the second embodiment include a positive electrode active material. Since the electron conductivity is high, when used as a positive electrode active material, the amount of conductive material used can be reduced, and the capacity of the battery can be increased. Moreover, the lithium nitride phosphate compound of the second embodiment can be obtained, for example, by the method described in “A. Method for producing lithium nitride phosphate compound” above.

3. Third Embodiment A third embodiment of the lithium oxynitride compound of the present invention is selected from the group consisting of Li _{a Xb} Y _{c Pd} O _e F _f N _g (X is 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, and 0.002 ≦ g ≦ 2.0).

According to the third embodiment, since it has the above composition, it can be a lithium nitride lithium phosphate compound having high Li ion conductivity and electron conductivity. Furthermore, since it has F in the composition, it can be a lithium nitride phosphate compound excellent in Li ion conductivity, electron conductivity, and durability. This lithium nitride phosphate compound is usually a compound having an olivine structure. In addition, the lithium nitride phosphate compound of the third embodiment is not obtained by simply adsorbing F and N to Li _{a Xb} Y _c P _d O _e , but in a state where F and N are chemically bonded, it is present in the compounds in _{(Li a X b Y c P} d O e F f N g). Moreover, in this invention, it is preferable that the lithium nitride phosphoric acid compound of 3rd embodiment is a particulate form (powder form). About an average particle diameter etc., it is the same as that of the content mentioned above.

The use of the lithium nitride lithium phosphate compound of the third embodiment is the same as that of the second embodiment described above. Moreover, the lithium nitride phosphate compound of the third embodiment can be obtained, for example, by the method described in the above-mentioned “A. Method for producing lithium nitride phosphate compound”.

C. Solid Electrolyte Layer The solid electrolyte layer of the present invention is characterized by containing the above-mentioned compound (compound (I)) having a NASICON (LISICON) type structure. According to this invention, it can be set as the solid electrolyte layer excellent in Li ion conductivity by using the compound (I) mentioned above. Thereby, the high output of a battery can be achieved. The thickness of the solid electrolyte layer of the present invention is not particularly limited, but for example, it is preferably in the range of 0.1 μm to 1000 μm, and more preferably in the range of 0.1 μm to 300 μm. Moreover, as a formation method of a solid electrolyte layer, the method of compression-molding the composition containing compound (I) etc. can be mentioned, for example. In addition, compound (I) may be contained in the positive electrode active material layer.

D. Positive electrode active material layer The positive electrode active material layer of the present invention is characterized by containing the above-described compound (compound (II) or compound (III)) having an olivine structure. According to this invention, it can be set as the positive electrode active material layer excellent in electronic conductivity by using compound (II) or compound (III) mentioned above. The positive electrode active material layer of the present invention contains at least the above-described compound, and may contain a conductive material as necessary. Examples of the conductive material include acetylene black, ketjen black, and carbon fiber. The thickness of the positive electrode active material layer of the present invention is preferably in the range of 0.1 μm to 1000 μm, for example. Moreover, as a formation method of a positive electrode active material layer, the method of compression-molding the composition containing compound (II) or compound (III) etc. can be mentioned, for example.

Note that 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.

The present invention will be described more specifically with reference to the following examples.

[Example 1-1]
Li ₃ PO ₄ (manufactured by Aldrich, average particle size 4 μm) 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 fired at 500 ° C. for 3 hours in a tubular furnace. Thereby, a lithium nitride phosphate compound (LIPON) was obtained. In addition, the specific surface area was measured by the BET method with respect to the obtained lithium nitride phosphate compound. For the measurement, a specific surface area and pore distribution fully automatic gas adsorption measuring device (Auto Soap-1, manufactured by Yuasa Ionics Co., Ltd.) was used. As a result, the specific surface area of the obtained lithium nitride lithium phosphate compound was 0.9 m ² / g.

[Examples 1-2 to 1-7]
A lithium nitride lithium phosphate compound (LIPON) was obtained in the same manner as in Example 1-1 except that the ratio of Li ₃ PO ₄ and urea, the firing temperature, and the firing time were changed to the conditions shown in Table 2 described later. It was.

[Comparative Example 1-1]
Iriyama et al., “Development of all-solid-state thin film rechargeable lithium batteries with high power density by interface regulation approaches”, NEDO FY2002 Industrial Technology Research Grants Results Report, Project ID 01B60011c Then, using a high-frequency magnetron sputtering method, a lithium nitride lithium phosphate compound (LIPON thin film) was obtained.

[Comparative Example 1-2]
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.

[Evaluation 1]
Chemical bonding state evaluation, crystal structure evaluation, and ion conductivity using the lithium nitride phosphate compounds of Examples 1-1 to 1-7 and Comparative Example 1-1 and the evaluation composition of Comparative Example 1-2 Evaluation was performed.

(1) Evaluation method (chemical bond state evaluation)
The chemical bonding state was evaluated by photoelectron spectroscopy (XPS method). The measurement conditions are shown below.
Measuring instrument: SSI, X-ray photoelectron spectrometer SSX-100
Excitation X-ray: Monochrome AlKα _1,2 line (1486.6 eV)
X-ray diameter: 300 × 525 μm ellipse Escape angle: 35 °

(Crystal structure evaluation)
The crystal structure was evaluated by an X-ray diffraction method (XRD method). RINT-TTR III manufactured by Rigaku Corporation was used as the X-ray diffractometer.

(Ion conductivity evaluation)
Ion conductivity was evaluated by an impedance analysis method. A frequency response analyzer 1260 manufactured by Solartron was used as the impedance measuring device. The impedance was measured in the range of 1 Hz to 10 MHz by sandwiching a pellet obtained by molding a measurement sample into 1 cmφ × 2 mmt with a molding machine and firing it at 500 ° C. for 1 hour. . From the arc shape of the obtained cole-cole plot, the ionic conductivity of the measurement sample was determined.

(2) Evaluation Results Chemical bonding state evaluation was performed on the lithium nitride phosphate compounds of Example 1-1 and Comparative Example 1-1 and the evaluation composition of Comparative Example 1-2. The result is shown in FIG. According to the analysis of the binding state of N, in FIG. 3 (a), a-1 is a peak of ON = O unit, a-2 is a peak of NP ₃ unit, and a-4 is a peak of NP ₂ unit. It was confirmed that. Note that a-3 is a peak due to residual urea. Similarly, in FIG. 3 (b), b-1 is a peak of ON = O unit, b-2 is a peak of NP ₃ unit, and b-4 is a peak of NP ₂ unit. confirmed. In contrast, in FIG. 3C, the 402.3 eV peak and the c-4 peak are peaks due to urea. A comparison of the peaks of Example 1-1 and Comparative Example 1-1 is shown in Table 1.

As shown in Table 1, it can be confirmed that there are three types of nitrogen bonding states. Further, when the lithium nitride phosphate compound obtained by firing (Example 1-1) and the lithium nitride phosphate compound obtained by sputtering (Comparative Example 1-1) were compared, N was bonded to each other. Have a state. For this reason, it was confirmed that the lithium nitride phosphate compound similar to that formed by the sputtering method can be obtained by the method for producing the lithium nitride phosphate compound of the present invention.

The crystal structure evaluation was performed on the lithium nitride lithium phosphate compound of Example 1-1. FIG. 4 shows the result of the XRD measurement. As a result of the analysis, a peak of Li ₃ PO ₄ was detected, and at the same time, a peak similar to Li ₄ P ₂ O ₇ was detected. Here, Li ₄ P ₂ O ₇ has O ₃ P—O—PO ₃ units. From the above XPS analysis results, it was confirmed that the P—N—P unit was found, and thus the lithium nitride lithium compound obtained in Example 1-1 had an O ₃ P—N—PO ₃ unit. I guess that. That is, this result suggests that the nitrogen element of the nitriding agent is not simply adsorbed on the surface of Li ₃ PO ₄ but is incorporated in the chemical bond.

The ion conductivity was evaluated for the lithium nitride nitride compounds of Examples 1-1 to 1-7 and the evaluation composition of Comparative Example 1-2. The results are shown in Table 2.

As shown in Table 2, the lithium nitride phosphate compound of Example 1-1 has an ionic conductivity 20 times or more that of the evaluation composition of Comparative Example 1-2. The reason for this is presumed to be that the O ₃ PN—PO ₃ unit described above was formed. Thus, according to the present invention, it was confirmed that a lithium nitride phosphate compound excellent in ion conductivity can be obtained by a simple method. Similarly, the lithium nitride phosphate compounds of Examples 1-2 to 1-7 exhibited high ionic conductivity with respect to the evaluation composition of Comparative Example 1-2. Further, from the results of Examples 1-1 to 1-7, it was found that the firing temperature is preferably 400 ° C. or higher, and more preferably 500 ° C. or higher. Further, from the results of Examples 1-1, 1-3, and 1-4, it was shown that the higher the ratio of urea to Li ₃ PO _{4, the} higher the ionic conductivity.

[Example 2]
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.

[Comparative Example 2]
Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ used in Example 2 was used as an evaluation composition.

[Evaluation 2]
Chemical bonding state evaluation, crystal structure evaluation, and ion conductivity evaluation were performed using the lithium nitride phosphate compound of Example 2 and the evaluation composition of Comparative Example 2. These evaluation methods are as described above.

The chemical bonding state evaluation was performed on the lithium nitride nitride compound of Example 2 and the evaluation composition of Comparative Example 2. FIG. 5 shows the result of the lithium nitride lithium phosphate compound of Example 2. By analysis of the binding state of N, it was confirmed that a-1 is a peak of ON = O unit, a-2 is a peak of NP ₃ unit, and a-4 is a peak of NP ₂ unit. . Note that a-3 is a peak due to residual urea. On the other hand, since the composition for evaluation of Comparative Example 2 did not have N, these peaks were not detected. Table 3 shows a comparison of the peaks of Example 2, Comparative Example 2 and Example 1-1 as a reference.

As shown in Table 3, when the lithium nitride phosphate compound obtained in Example 2 and the lithium nitride phosphate compound obtained in Example 1-1 were compared, N had a bonding state equivalent to each other. is doing. Therefore, it was confirmed that a desired lithium nitride phosphoric acid compound can be obtained.

The ion conductivity evaluation was performed on the lithium nitride nitride compound of Example 2 and the evaluation composition of Comparative Example 2. The results are shown in Table 4.

As shown in Table 4, it was confirmed that the lithium nitride lithium compound of Example 2 had about twice the ionic conductivity with respect to the evaluation composition of Comparative Example 2.

[Example 3]
0.48 g of Li ₂ CO ₃ , 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 (LiFePO ₄ ) having an olivine structure. Next, 1 g of each of the obtained raw material compound and urea (manufactured by Aldrich) 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 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 Example 3]
The raw material compound obtained in Example 3 was molded into 1 cmφ × 2 mmt with 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.

[Example 4]
0.24 g of Li ₂ CO ₃ , 0.34 g of LiF, 2.34 g of FeC ₂ O ₄ , 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 Example 3 except that the obtained raw material compound was used. The color of the obtained lithium nitride nitride compound was dark brown.

[Example 5]
0.48 g of Li ₂ CO ₃ , 2.39 g of CoC 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 (LiCoPO ₄ ) having an olivine structure. A lithium nitride lithium phosphate compound was obtained in the same manner as in Example 3 except that the obtained raw material compound was used.

[Comparative Example 4]
The raw material compound obtained in Example 5 was molded into 1 cmφ × 2 mmt with a molding machine and baked under conditions of 750 ° C. and 24 hours in an Ar atmosphere to obtain a composition for evaluation.

[Evaluation 3]
XRD measurement was performed using the lithium nitride phosphate compound of Examples 3 and 4 and the composition for evaluation of Comparative Example 3. The results are shown in FIGS. As shown in FIG. 6, it was confirmed that Example 3 showed an equivalent peak to Comparative 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 Example 3, N could be introduced into the iron olivine structure without impurities. Further, as shown in FIG. 7, it was confirmed that Example 4 showed an equivalent peak to Comparative 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 Example 4, N and F could be introduced into the iron olivine structure without impurities. 6 and 7, in Examples 3 and 4, a peak was detected at around 28 °. This peak is not detected in Comparative Example 3, but is considered to be due to the influence of residual urea.

Further, electron conductivity measurement was performed using the lithium nitride phosphate compounds of Examples 3 to 5 and the evaluation compositions of Comparative Examples 3 and 4. The measurement conditions of electron conductivity are shown below.
・ Measuring device: MCP-PD51, manufactured by Mitsubishi Chemical Analytech
・ Sample shape: Fill a sample in a cylinder of φ20mm and pressurize to 20kN ・ Measurement method: Measure current value with 90V voltage applied by 4-terminal method, calculate resistance, and calculate the value By converting to the reciprocal, the electron conductivity is obtained.
The results are shown in Table 5.

As shown in Table 5, it was confirmed that the lithium nitride phosphate compounds of Examples 3 and 4 had higher electronic conductivity than the evaluation composition of Comparative Example 3. Similarly, it was confirmed that the lithium nitride phosphoric acid compound of Example 5 had higher electronic conductivity than the evaluation composition of Comparative Example 4. In particular, from the results of Examples 3 and 4, it was found that by introducing F, the electron conductivity was further improved. By increasing the electron conductivity, the amount of conductive material used can be reduced, and the capacity of the battery can be increased.

Claims (19)

1. A preparation step of preparing a raw material composition containing a raw material compound having an Li element and a PO ₄ skeleton, and a nitriding agent represented by the following general formula (1):
   Firing the raw material composition, and synthesizing a lithium nitride phosphate compound;
   A method for producing a lithium nitride lithium phosphate compound, comprising:
   

   

   In the general formula (1), R ₁ , R ₂ and R ₃ are each independently a functional group having at least one of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). is there.
2. The method for producing a lithium nitride lithium phosphate compound according to claim 1, wherein the raw material compound is Li ₃ PO ₄ .
3. The method for producing a lithium lithium phosphate compound according to claim 1, wherein the raw material compound is a mixture of Li ₂ CO ₃ and (NH ₄ ) H ₂ PO ₄ .
4. The raw material compound is Li _{a Xb} Y _{cP d} O _e (X is at least one selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al, and Y is B, Al, At least one selected from the group consisting of 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, 0 ≦ c <2.98, 0.02 <d ≦ 3.0, 2.0 <c + d <4.0, 3.0 <e ≦ 12.0. The method for producing a lithium nitride lithium phosphate compound according to claim 1, wherein:
5. The raw material compound 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 Mg, Al, Ti, Ga, Cu, At least one selected from the group consisting of 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) The method for producing a lithium nitride lithium phosphate compound according to claim 1,
6. The raw material compound is 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 Mg, Al, Ti, Ga, It is at least one selected from the group consisting of 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 The method for producing a lithium nitride lithium phosphate compound according to claim 1, wherein the compound is represented by the following formula:
7. 6. The method according to claim 6, further comprising a synthesis step of synthesizing the raw material compound using a mixture containing a Li source, an X source, a Y source, a PO ₄ source and an F source before the preparation step. The manufacturing method of lithium nitride phosphoric acid compound as described in claim | item.
8. The method for producing a lithium nitride lithium compound according to any one of claims 1 to 7, wherein the nitriding agent is solid or liquid at normal temperature (25 ° C).
9. The method for producing a lithium nitride lithium phosphate compound according to any one of claims 1 to 8, wherein the nitriding agent is urea.
10. The method for producing a lithium nitride lithium compound according to any one of claims 1 to 9, wherein a firing temperature in the synthesis step is in a range of 100 ° C to 800 ° C. .
11. The method for producing a lithium nitride lithium compound according to any one of claims 1 to 10, wherein a firing time in the synthesis step is within a range of 10 minutes to 7 hours. .
12. _{Li a X b Y c P d} O e N f (X is at least one selected Ti, Zr, Ge, In, Ga, from the group consisting of Sn and Al, Y is 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 A lithium nitride phosphate compound, wherein
13. _{Li a X b Y c P d} O e N f (X is at least one selected from the group consisting of Mn, Fe, Co and Ni, Y is 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) A lithium nitride phosphate compound characterized by the above.
14. _{Li a X b Y c P d} O e F f N g (X is at least one selected from the group consisting of Mn, Fe, Co and Ni, Y is 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 is satisfied).
15. 15. The lithium nitride lithium phosphate compound according to any one of claims 12 to 14, which is in the form of particles.
16. 16. The lithium nitride phosphate compound according to claim 15, wherein the average particle size is in the range of 100 nm to 100 μm.
17. The lithium nitride phosphate compound according to claim 15 or 16, wherein the specific surface area is in the range of 0.1 m ² / g to 300 m ² / g.
18. A solid electrolyte layer comprising the lithium nitride lithium phosphate compound according to claim 12.
19. A positive electrode active material layer comprising the lithium nitride phosphoric acid compound according to claim 13 or 14.

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