JP6364945B2 - Lithium ion secondary battery - Google Patents

Description

  The present invention relates to a lithium ion secondary battery.

  In recent years, the development of electronic technology has been remarkable, and portable electronic devices have been made smaller, lighter, thinner, and multifunctional. As a result, there is a strong demand for smaller, lighter, thinner, and more reliable batteries that serve as power sources for electronic devices, and all-solid-state lithium-ion secondary batteries that use a solid electrolyte as the electrolyte are attracting attention. Yes.

  In general, all solid-state lithium ion secondary batteries are classified into two types: thin film type and bulk type. The thin film type is produced by thin film technology such as PVD method or sol-gel method, and the bulk type is produced by powder molding of an active material or a sulfide-based solid electrolyte having low grain boundary resistance. However, since it is difficult to increase the thickness of the active material layer or to increase the number of layers, the thin film type has a problem that the capacity is small and the manufacturing cost is high. On the other hand, a sulfide-type solid electrolyte is used for the bulk type, and hydrogen sulfide is generated when it reacts with water. Therefore, it is necessary to produce a battery in a glove box in which the dew point is controlled. In addition, since it is difficult to form a sheet, it is a problem to reduce the thickness of the solid electrolyte layer and to increase the battery stack.

In view of such a problem, in Patent Document 1, an oxide-based solid electrolyte that is stable in the air is used, and each member is formed into a sheet, laminated, and then fired at the same time. An all solid state battery produced by a manufacturing method has been proposed. However, since different materials are fired at the same time, it has been difficult to firmly bond the positive electrode layer, the negative electrode layer, and the solid electrolyte layer.
Therefore, Patent Document 2 discloses a solid electrolyte battery having an intermediate layer made of a substance that functions as an active material or an electrolyte at the interface between the positive electrode layer and / or the negative electrode layer and the solid electrolyte layer. Patent Document 3 discloses that a region constituting a compound containing at least one element of an electrode material and one element of a solid electrolyte is formed at the interface between at least one electrode and the solid electrolyte.

Japanese Patent Publication No. 07-135790 International Publication No. 2008/143027 JP 2004-281316 A

  However, in the solid electrolyte battery described above, the amount of the active material is reduced by forming the intermediate layer using the active material contained in the active material layer, and sufficient battery capacity cannot be obtained.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to improve the discharge capacity of a lithium ion secondary battery using a solid electrolyte.

  In order to solve the above-described problems, a lithium ion secondary battery according to the present invention includes a positive electrode current collector layer, a positive electrode layer composed of a positive electrode active material layer disposed on the positive electrode current collector layer, a negative electrode current collector layer, In a lithium ion secondary battery in which a negative electrode layer composed of a negative electrode active material layer disposed on a negative electrode current collector layer and a positive electrode layer and a negative electrode layer are laminated via an electrolyte layer, the positive electrode active material layer and the negative electrode active material At least one of the layers includes a first compound composed of lithium vanadium phosphate as an active material and a second compound composed of at least one of a metal phosphate, a metal pyrophosphate, and a metal vanadate, The ratio B / A of the particle diameter B of the second compound particles to the particle diameter A of the compound particles is 0.01 <B / A <0.2, and the content of the second compound is 0.1 It is -7.2 wt%.

ADVANTAGE OF THE INVENTION According to this invention, the discharge capacity of the solid battery using this can be improved.
Although this mechanism is not clear, it is considered that it is as follows.
That is, the reaction contact field is increased by filling the second compound particles between the first compound particles, and the ratio of the particle diameter A of the first compound particles to the particle diameter B of the second compound particles is 0. When .01 <B / A, 0.2 and the content of the second compound is 0.1 to 7.2 wt%, it is considered that the discharge capacity is improved due to high active material filling properties.

  In the above invention, the positive electrode active material layer and the negative electrode active material layer both include first compound particles made of lithium vanadium phosphate as an active material, and at least one of metal phosphate, metal pyrophosphate, and metal vanadate. It is preferable that the 2nd compound particle which consists of is included.

  According to the present invention, it is considered that the discharge capacity is improved by using the active material described above for the positive electrode active material layer and the negative electrode active material layer, so that both the positive electrode active material layer and the negative electrode active material layer have high active material filling properties. .

In the present invention, the solid electrolyte is preferably a compound represented by the general formula Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ (0 ≦ x ≦ 0.6).

  According to the present invention, by using the above-described solid electrolyte material, the discharge capacity of a lithium ion secondary battery using the solid electrolyte material can be further improved.

  Moreover, in the said invention, it is preferable that a positive electrode collector layer and a negative electrode collector layer contain Cu.

  According to the present invention, by using Cu for the current collector layer, the discharge capacity of a lithium ion secondary battery using the current collector layer is improved. This is because the materials constituting the positive electrode current collector layer and the negative electrode current collector layer do not react with the positive electrode active material, the negative electrode active material, or the solid electrolyte, so that a decrease in capacity due to a side reaction can be suppressed.

  According to the present invention, a lithium ion secondary battery having a high discharge capacity can be provided.

FIG. 1 is a cross-sectional view showing a conceptual structure of a lithium ion secondary battery.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

(Structure of lithium ion secondary battery)
FIG. 1 is a cross-sectional view showing a conceptual structure of a lithium ion secondary battery 10 according to an example of the present embodiment. In the lithium ion secondary battery 10 of this embodiment, a positive electrode layer 1 and a negative electrode layer 2 are laminated via a solid electrolyte layer 3, and the positive electrode layer 1 includes a positive electrode current collector layer 4 and a positive electrode active material layer 5. The negative electrode layer 2 includes a negative electrode current collector layer 6 and a negative electrode active material layer 7.

  The solid electrolyte layer 3 includes an active material 8, and one or both of the positive electrode active material layer 5 and the negative electrode active material layer 7 include an active material 9 containing lithium vanadium phosphate. In FIG. 1, both the positive electrode active material layer 5 and the negative electrode active material layer 7 include the active material 9 containing lithium vanadium phosphate, but may be included in either one.

  The materials constituting the solid electrolyte layer 3, the positive electrode active material layer 5, and the negative electrode active material layer 7 of the lithium ion secondary battery 10 of this embodiment can be identified by X-ray diffraction measurement. Further, the diffusion of titanium and aluminum can be analyzed by EDS or WDS element mapping of the cross section of the lithium ion secondary battery 10.

  FIG. 1 shows a cross-sectional view of a lithium ion secondary battery 10 composed of a pair of positive electrode layer and negative electrode layer. However, the technology relating to the lithium ion secondary battery 10 of the present embodiment is not limited to FIG. 1, and can be applied to the lithium ion secondary battery 10 in which an arbitrary plurality of layers are stacked, and the required capacity of the lithium ion secondary battery 10. It can be changed widely according to the current specification.

(Solid electrolyte)
As the solid electrolyte 8 constituting the solid electrolyte layer 3 of the lithium ion secondary battery 10 of the present embodiment, it is preferable to use a material having low electron conductivity and high lithium ion conductivity. For example, Li _{3 + x1} Si _x1 P _1-x1 O ₄ (0.4 ≦ x1 ≦ 0.6), Li _{1 + x2} Al _x2 Ti _2-x2 (PO ₄ ) ₃ (0 ≦ x2 ≦ 0.6), germanium phosphate At least one selected from the group consisting of lithium (LiGe ₂ (PO ₄ ) ₃ ), Li ₂ O—V ₂ O ₅ —SiO ₂ , Li ₂ O—P ₂ O ₅ —B ₂ O ₃ , Li ₃ PO _4. It is desirable to be a seed.

(Positive electrode active material and negative electrode active material)
A first compound in which at least one of the positive electrode active material layer 5 and the negative electrode active material layer 7 of the lithium ion secondary battery 10 of the present embodiment is composed of lithium vanadium phosphate, a metal phosphate, a metal pyrophosphate, and a metal vanazine A second compound comprising at least one of the acid salts.

Lithium vanadium phosphate which is the first compound is LiVOPO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , Li ₂ VOP ₂ O ₇ , Li ₂ VP ₂ O ₇ , Li ₄ (VO) (PO ₄ ) ₂ , And Li ₉ V ₃ (P ₂ O ₇ ) ₃ (PO ₄ ) ₂ , preferably one or more of LiVOPO ₄ and Li ₃ V ₂ (PO ₄ ) _3. It is preferable. Further, the positive electrode active material layer 5 and the negative electrode active material 7 may contain a positive electrode active material and a negative electrode active material other than lithium vanadium phosphate.

For example, it preferably contains a transition metal oxide or a transition metal composite oxide. Specifically, the lithium manganese composite oxide _{Li 2 Mn x3 Ma 1-x3} O 3 (0.8 ≦ x3 ≦ 1, Ma = Co, Ni), lithium cobaltate (LiCoO _2), lithium nickelate (LiNiO ₂ ), Lithium manganese spinel (LiMn ₂ O ₄ ), and a general formula: LiNi _x4 Co _y4 Mn _z4 O ₂ (x4 + y4 + z4 = 1, 0 ≦ x4 ≦ 1, 0 ≦ y4 ≦ 1, 0 ≦ z4 ≦ 1) Composite metal oxide, lithium vanadium compound (LiV ₂ O ₅ ), olivine type LiMbPO ₄ (where Mb is one or more selected from Co, Ni, Mn, Fe, Mg, Nb, Ti, Al, Zr) elements), Li excess solid solution positive electrode _{Li 2 MnO 3 -LiMcO 2 (Mc} = Mn, Co, Ni), lithium titanate _(Li 4 _Ti 5 O ₂₎ is preferably any one of _{Li a Ni x5 Co y5 Al z5} O 2 (0.9 <a <1.3,0.9 <x5 + y5 + z5 composite metal oxide represented by <1.1) .

The second compound consisting of at least one of metal phosphate, metal pyrophosphate, and metal vanadate as the second compound is, for example, LiMPO ₄ (M = Fe, Mn, Co, At least one element selected from Ni, Al, Ti, V, VO), MPO ₄ (M = at least one element selected from Fe, Mn, Co, Ni, Al, Ti, V, VO), metal pyrophosphate Li ₂ MP ₂ O ₇ (M = Fe, Mn, Co, Ni, Al, Ti, V, VO) as the salt, and LiMVO ₄ (M = Fe, Mn) as the metal vanadate , at least one element selected Co, Ni, Al, from _{Ti), MVO 4 (M =} Fe, Mn, Co, Ni, Al, at least one element selected from Ti) etc. is increased, et al It is preferable that these be any one or more preferably, compounds especially those containing V, such as LiVOPO _4, VOPO _4.

  Here, there is no clear distinction between the active materials constituting the positive electrode active material layer 5 or the negative electrode active material layer 7, and a compound showing a more noble potential is compared as a positive electrode active material by comparing the potentials of two types of compounds. A compound showing a lower potential can be used as the negative electrode active material. Further, the same compound may be used for the positive electrode active material layer 5 and the negative electrode active material layer 7 as long as the compound has both lithium ion releasing ability and lithium ion storage ability.

  The lithium ion secondary battery according to the present embodiment includes a positive electrode current collector layer, a positive electrode layer including a positive electrode active material layer disposed on the positive electrode current collector layer, a negative electrode current collector layer, and the negative electrode current collector layer. In a lithium ion secondary battery in which a negative electrode layer composed of a negative electrode active material layer disposed on the positive electrode layer and the negative electrode layer are laminated via an electrolyte layer, the positive electrode active material layer and the negative electrode active material layer At least one of the first compound composed of lithium vanadium phosphate as an active material and the second compound composed of at least one of metal phosphate, metal pyrophosphate, and metal vanadate, The ratio B / A of the particle diameter B of the second compound particle to the particle diameter A of the compound particle is 0.01 <B / A <0.2, and the content of the second compound is 0.00. It is desirable that it is 1 to 7.2 wt%.

  The reaction contact field is increased by filling the second compound particles between the first compound particles, and the ratio of the particle size A of the first compound particles to the particle size B of the second compound particles is 0. When 01 <B / A, 0.2 and the content of the second compound is 0.1 to 7.2 wt%, it is considered that the discharge capacity is improved due to high filling properties.

  The ratio B / A of the particle diameter B of the second compound particle to the particle diameter A of the first compound particle is more preferably 0.03 <B / A <0.15, More preferably, the amount of the compound is 1.0 to 5.7 wt%.

  Thereby, the discharge capacity of the lithium ion secondary battery in the present embodiment can be further improved.

  The particle diameter A of the first compound particles and the particle diameter B of the second compound particles can be evaluated by observing the cross section of the lithium ion secondary battery in the present embodiment with SEM, TEM, or the like.

  When the cross section of the lithium ion secondary battery in this embodiment is observed with an SEM, the first compound particles and the second compound particles are observed in the positive electrode active material layer or the negative electrode active material layer, and 100 first compound particles are obtained. The average particle diameter of A and the average particle diameter of 100 second compound particles as B can be calculated as B / A.

  Moreover, there is no clear distinction in the active material which comprises the positive electrode active material layer 5 or the negative electrode active material layer 7, Comparing the electric potential of two types of compounds, and using the compound which shows a more noble electric potential as a positive electrode active material A compound exhibiting a lower potential can be used as the negative electrode active material.

(Positive electrode current collector layer and negative electrode current collector layer)
As the current collector material constituting the positive electrode current collector layer 4 and the negative electrode current collector layer 6 of the lithium ion secondary battery 10 of the present embodiment, it is preferable to use a material having a high conductivity, for example, silver, palladium, Gold, platinum, aluminum, copper, nickel, etc. are preferably used. In particular, copper is preferable because it hardly reacts with the positive electrode active material, the negative electrode active material, and the solid electrolyte, and further has an effect of reducing the internal resistance of the lithium ion secondary battery 10. The materials constituting the positive electrode current collector layer 4 and the negative electrode current collector layer 6 may be the same for the positive electrode and the negative electrode, or may be different.

  The materials constituting the positive electrode current collector layer 4 and the negative electrode current collector layer 6 of the lithium ion secondary battery 10 in this embodiment preferably include a positive electrode active material or a negative electrode active material in addition to the current collector material. .

  Adhesion between the current collector layer and the positive electrode active material layer or the negative electrode active material layer is improved by using a composite of the current collector material and the active material for the positive electrode current collector layer or the negative electrode current collector layer. This is desirable.

  The composite ratio of the current collector material and the active material in the current collector layer in the present embodiment is not particularly limited as long as it functions as a current collector.

(Method for producing lithium ion secondary battery)
In the lithium ion secondary battery 10 of this embodiment, the positive electrode current collector layer 4, the positive electrode active material layer 5, the solid electrolyte layer 3, the negative electrode active material layer 7, and the negative electrode current collector layer 6 are pasted. The green sheet is produced by coating and drying, the green sheets are laminated, and the produced laminate is fired at the same time.

  The method for forming the paste is not particularly limited, and for example, a paste can be obtained by mixing the powder of each of the above materials in a vehicle. Here, the vehicle is a general term for the medium in the liquid phase. The vehicle includes a solvent and a binder. By such a method, the paste for the positive electrode current collector layer 4, the paste for the positive electrode active material layer 5, the paste for the solid electrolyte layer 3, the paste for the negative electrode active material layer 7, and the negative electrode current collector layer 6 Make a paste.

  The prepared paste is applied in a desired order on a substrate such as PET and dried as necessary, and then the substrate is peeled off to produce a green sheet. The paste application method is not particularly limited, and a known method such as screen printing, application, transfer, doctor blade, or the like can be employed.

  The green sheets for the positive electrode current collector layer 4, the positive electrode active material layer 5, the solid electrolyte layer 3, the negative electrode active material layer 7, and the negative electrode current collector layer 6 that are produced are laminated in a desired order. Stacked by number, alignment, cutting, etc. are performed as necessary to produce a laminate. In the case of manufacturing a parallel type or series-parallel type battery, it is preferable to align and stack the end surfaces of the positive electrode layer and the negative electrode layer so that they do not coincide with each other.

  The produced laminate is pressed together. The pressure bonding is performed while heating, and the heating temperature is, for example, 40 to 90 ° C.

  For example, the pressure-bonded laminate is heated and fired in a nitrogen atmosphere. In manufacture of the lithium ion secondary battery 10 of this embodiment, it is preferable that a calcination temperature shall be the range of 720-1000 degreeC. When the temperature is lower than 720 ° C., diffusion and sintering of titanium and aluminum do not proceed sufficiently, and when the temperature exceeds 1000 ° C., problems such as melting of lithium vanadium phosphate occur. Furthermore, it is more preferable to set it as the range of 750-900 degreeC. A range of 750 to 900 ° C. is more preferable for accelerating diffusion and sintering of titanium and aluminum and reducing manufacturing costs. The firing time is, for example, 0.1 to 3 hours.

Example 1
EXAMPLES The present invention will be described in detail below using examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, a part display is a weight part.

(Preparation of the first compound)
As the first compound, Li ₃ V ₂ (PO ₄ ) ₃ prepared by the following method was used. Using Li ₂ CO ₃ , V ₂ O ₅ and NH ₄ H ₂ PO ₄ as starting materials, these were weighed so as to have a molar ratio of 3: 2: 6, and wet mixed in a ball mill for 16 hours using water as a solvent. And then dehydrated and dried. The obtained powder was calcined in a nitrogen-hydrogen mixed gas at 850 ° C. for 2 hours. The calcined product was roughly pulverized, wet-ground by a ball mill for 120 minutes using water as a solvent, and then dehydrated and dried to obtain a first compound powder. The average particle size of this powder was 3.0 μm. The composition of the powder produced is _Li 3 _V 2 _{(PO 4)} is _3, was confirmed using X-ray diffractometer.

(Preparation of the second compound)
As the second compound, LiVOPO ₄ prepared by the following method was used. Using Li ₂ CO ₃ , V ₂ O ₅ and NH ₄ H ₂ PO ₄ as starting materials, these were weighed so as to have a molar ratio of 1: 1: 2, and wet-mixed for 16 hours in a ball mill using water as a solvent. And then dehydrated and dried. The obtained powder was baked in the air at 550 ° C. for 4 hours. The fired product was coarsely pulverized in an agate mortar and dry pulverized for 60 minutes with a ball mill to obtain a second compound powder. The average particle size of this powder was 0.33 μm. The composition of the powder produced is LiVOPO _4, was confirmed using X-ray diffractometer.

(Production of active material paste)
The active material paste is kneaded and dispersed with three rolls by adding 15 parts of ethyl cellulose as a binder and 65 parts of dihydroterpineol as a solvent to 5 parts of the second compound powder with respect to 100 parts of the first compound powder. An active material paste was prepared.

(Preparation of solid electrolyte sheet)
As the solid electrolyte, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ prepared by the following method was used. Using Li ₂ CO ₃ , Al ₂ O ₃ , TiO ₂ and NH ₄ H ₂ PO ₄ as starting materials, these were weighed to a molar ratio of 0.65: 0.15: 1.7: 3, and water was added. After wet mixing with a ball mill as a solvent for 16 hours, it was dehydrated and dried. The obtained powder was calcined in air at 800 ° C. for 2 hours. The calcined product was coarsely pulverized, wet pulverized with a ball mill for 24 hours using water as a solvent, and then dehydrated to obtain a solid electrolyte powder. The average particle size of this powder was 0.2 μm. The composition of the powder produced is _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is _3, was confirmed using X-ray diffractometer.

  Next, 100 parts of ethanol and 200 parts of toluene were added to 100 parts of the powder by a ball mill and wet mixed. Thereafter, 16 parts of polyvinyl butyral binder and 4.8 parts of benzylbutyl phthalate were further added and mixed to prepare a solid electrolyte paste. This solid electrolyte paste was formed into a sheet by a doctor blade method using a PET film as a base material to obtain a solid electrolyte sheet having a thickness of 15 μm.

(Preparation of current collector paste)
After mixing Cu powder and Li ₃ V ₂ (PO ₄ ) ₃ as a current collector so as to have a volume ratio of 60:40, 10 parts of ethyl cellulose as a binder and 50 parts of dihydroterpineol as a solvent were added, and three of them were added. A current collector paste was prepared by kneading and dispersing with a roll. The average particle diameter of Cu was 0.6 μm.

(Preparation of terminal electrode paste)
Silver powder, epoxy resin, and solvent were kneaded and dispersed with three rolls to produce a thermosetting conductive paste.

  Using these pastes, lithium ion secondary batteries were produced as follows.

(Production of active material unit)
An active material paste was printed on the solid electrolyte sheet with a thickness of 5 μm by screen printing. Next, the printed active material paste was dried at 80 to 100 ° C. for 5 to 10 minutes, and the current collector paste was printed thereon with a thickness of 5 μm by screen printing. Next, the printed current collector paste was dried at 80 to 100 ° C. for 5 to 10 minutes, and further, the active material paste was printed again at a thickness of 5 μm by screen printing. The printed active material paste was dried at 80 to 100 ° C. for 5 to 10 minutes, and then the PET film was peeled off. In this way, an active material unit sheet in which the active material paste, the current collector paste, and the active material paste were printed and dried in this order on the solid electrolyte sheet was obtained.

(Production of laminate)
Two active material units were stacked with a solid electrolyte interposed therebetween. At this time, the current collector paste layer of the first active material unit extends only to one end surface, and the current collector paste layer of the second active material unit extends only to the other surface, Each unit was staggered and stacked. A solid electrolyte sheet was stacked on both surfaces of the stacked unit so as to have a thickness of 500 μm, and then this was molded at a temperature of 80 ° C. and a pressure of 1000 kgf / cm ² [98 MPa], and then cut to prepare a laminated block. . Thereafter, the laminated block was simultaneously fired to obtain a laminated body. In the simultaneous firing, the temperature was increased to a firing temperature of 840 ° C. at a temperature rise rate of 200 ° C./hour in nitrogen, maintained at that temperature for 2 hours, and naturally cooled after firing. The battery appearance size after co-firing was 3.2 mm × 2.5 mm × 0.4 mm.

(Terminal electrode formation process)
A terminal electrode paste was applied to the end face of the laminate, and thermosetting was performed at 150 ° C. for 30 minutes to form a pair of terminal electrodes to obtain a lithium ion secondary battery.

(Calculation of particle size ratio of first compound particle and second compound particle)
When the cross section of the lithium ion secondary battery obtained in Example 1 was analyzed by XRD, Li ₃ V ₂ (PO ₄ ) ₃ and LiVOPO ₄ were used for the active material layer, and Li _1.3 Al ₀ was used for the solid electrolyte layer. _.3 Ti _1.7 (PO ₄ ) ₃ was confirmed. Further, when observed by SEM, 100 each of the first compound particles and the second compound particles in the active material layer were observed, and the average particle diameter thereof was observed. The average particle diameter A of the first compound particles A = 3 It was confirmed that 0.0 μm and the average particle diameter B of the second compound particles were 0.33 μm, and 0.01 <B / A <0.2.

(Second compound content calculation)
When the cross section of the lithium ion secondary battery obtained in Example 1 was analyzed by XRD and the obtained results were quantitatively analyzed, the same amount of the second compound as the mixed second compound was found in the active material layer. It was found that it contained.

(Example 2)
A lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that the time of dry pulverization by a ball mill was 45 minutes in the production process of the second compound. The average particle diameter B of the obtained second compound was 0.57 μm, and the value of B / A was 0.19.

(Example 3)
A lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that the time of dry pulverization with a ball mill was set to 80 minutes in the production process of the second compound. The average particle diameter B of the obtained second compound was 0.42 μm, and the value of B / A was 0.14.

Example 4
A lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that the time of dry pulverization with a ball mill was set to 150 minutes in the production process of the second compound. The average particle diameter B of the obtained second compound was 0.12 μm, and the value of B / A was 0.04.

(Example 5)
A lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that the time of dry pulverization with a ball mill was 300 minutes in the production process of the second compound. The average particle size B of the obtained second compound was 0.06 μm, and the value of B / A was 0.02.

(Example 6)
In the production of the active material paste, the lithium ion secondary of Example 6 was used in the same manner as in Example 1 except that the amount of the second compound mixed was 0.1 parts by weight with respect to 100 parts by weight of the first compound. A battery was produced.

(Example 7)
In the production of the active material paste, the lithium ion secondary of Example 6 was made in the same manner as in Example 1 except that the amount of the second compound mixed was 0.3 parts by weight with respect to 100 parts by weight of the first compound. A battery was produced.

(Example 8)
In the production of the active material paste, the lithium ion secondary battery of Example 6 was prepared in the same manner as in Example 1 except that the amount of the second compound mixed was 1 part by weight with respect to 100 parts by weight of the first compound. Produced.

Example 9
In the production of the active material paste, the lithium ion secondary battery of Example 6 was manufactured in the same manner as in Example 1 except that the amount of the second compound mixed was 3 parts by weight with respect to 100 parts by weight of the first compound. Produced.

(Example 10)
In the production of the active material paste, the lithium ion secondary of Example 6 was made in the same manner as Example 1 except that the amount of the second compound mixed was 5.5 parts by weight with respect to 100 parts by weight of the first compound. A battery was produced.

(Example 11)
In the production of the active material paste, the lithium ion secondary of Example 6 was used in the same manner as in Example 1 except that the amount of the second compound mixed was 7.2 parts by weight with respect to 100 parts by weight of the first compound. A battery was produced.

(Examples 12 to 15)
In producing the active material paste, lithium ion secondary batteries of Examples 12 to 15 were produced in the same manner as in Example 1 except that the second compound to be mixed was changed.

(Comparative Example 1)
In the production of the active material paste, a lithium ion secondary battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the second compound was not mixed.

(Comparative Example 2)
In the production of the active material paste, the lithium ion secondary of Example 6 was used in the same manner as in Example 1 except that the amount of the second compound mixed was 7.4 parts by weight with respect to 100 parts by weight of the first compound. A battery was produced.

(Comparative Example 3)
In the production of the active material paste, the lithium ion secondary of Example 6 was used in the same manner as in Example 1 except that the amount of the second compound mixed was 9.3 parts by weight with respect to 100 parts by weight of the first compound. A battery was produced.

(Comparative Example 4)
In the production process of the second compound, the lithium ion secondary battery of Example 2 was obtained in the same manner as in Example 1 except that the grinding method using a ball mill was wet grinding using water as a solvent and the grinding time was 300 minutes. Produced. The average particle size B of the obtained second compound was 0.027 μm, and the value of B / A was 0.009.

(Comparative Example 5)
A lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1 except that in the production process of the second compound, dry pulverization by a ball mill was not performed. The average particle diameter B of the obtained second compound was 0.66 μm, and the value of B / A was 0.22.

(Battery evaluation)
Lead wires were attached to the respective terminal electrodes, and repeated charge / discharge tests were conducted. The measurement conditions were such that the current during charging and discharging was 0.2 μA, and the cutoff voltage during charging and discharging was 4.0 V and 0 V, respectively. Table 1 shows values of discharge capacity in the second charge / discharge cycle in which the charge / discharge behavior is stabilized under the above conditions.

  From Table 1, at least one of the positive electrode active material layer and the negative electrode active material layer includes at least one of a first compound composed of lithium vanadium phosphate as an active material, a metal phosphate, a metal pyrophosphate, and a metal vanadate. The ratio B / A of the particle size B of the second compound particle to the particle size A of the first compound particle is 0.01 <B / A <0.2. It was found that when the content of the second compound is 0.1 to 7.2 wt%, a high discharge capacity is exhibited. Further, from Examples 2 and 5, the ratio B / A of the particle diameter of the second compound particle to the particle diameter A of the first compound particle is 0.03 <B / A <0.15. Moreover, when content of the 2nd compound is 1.0-5.7, it has also confirmed that a favorable discharge capacity was shown.

  As described above, the lithium ion secondary battery according to the present invention is effective in improving the discharge capacity. Providing high capacity contributes greatly, especially in the field of electronics.

DESCRIPTION OF SYMBOLS 1 Positive electrode layer 2 Negative electrode layer 3 Solid electrolyte layer 4 Positive electrode collector layer 5 Positive electrode active material layer 6 Negative electrode collector layer 7 Negative electrode active material layer 8 Solid electrolyte 9 Active material 10 Lithium ion secondary battery

Claims (4)

A positive electrode layer comprising a positive electrode current collector layer, a positive electrode active material layer disposed on the positive electrode current collector layer, and a negative electrode current collector layer and a negative electrode active material layer disposed on the negative electrode current collector layer. In a lithium ion secondary battery in which a negative electrode layer, the positive electrode layer, and the negative electrode layer are stacked via a solid electrolyte layer,
At least one of the positive electrode active material layer and the negative electrode active material layer is made of at least one of a first compound made of lithium vanadium phosphate as an active material and a metal phosphate, a metal pyrophosphate, and a metal vanadate. Including a second compound;
Said second compound is LiMPO4 (at least one element selected from M = Fe, Mn, Co, Ni, Al, Ti, V, VO), MPO4 (M = Fe, Mn, Co, Ni, Al, Ti, Ti). , V, VO), Li2MP2O7 (M = Fe, Mn, Co, Ni, Al, Ti, V, VO), LiMVO4 (M = Fe, Mn, Co) , At least one element selected from Ni, Al, Ti), MVO4 (M = at least one element selected from Fe, Mn, Co, Ni, Al, Ti),
The ratio of the particle size ratio B / A of the second compound particles to the particle size A of the first compound particles is 0.01 <B / A <0.2,
The content of the second compound with respect to the content of the first compound is 0.1 to 7.2 wt%,
Lithium ion secondary battery. The positive electrode layer and the negative electrode layer both include first compound particles made of lithium vanadium phosphate as active materials and second compound particles made of at least one of metal phosphate and metal vanadate. And
The lithium ion secondary battery according to claim 1.   3. The lithium ion secondary battery according to claim 1, wherein the solid electrolyte layer is a compound represented by a general formula Li1 + xAlxTi2-x (PO4) 3 (0 ≦ x ≦ 0.6).   The lithium ion secondary battery according to claim 1, wherein the positive electrode current collector layer and the negative electrode current collector layer contain Cu.

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