JP6944113B2 - Positive electrode material and its manufacturing method, and battery and its manufacturing method - Google Patents

Description

The present invention relates to a positive electrode material and a method for producing the same, and a battery and a method for producing the same.

Energy harvesting technology that stores electricity generated from minute energies such as solar energy, vibration energy, and body temperature of humans and animals and uses it for sensors, wireless transmission power, etc. is safe and reliable in all global environments. A secondary battery is required.

In a liquid-based battery using an organic solvent solution that is widely used at present, there is a concern that the positive electrode active material deteriorates as the cycle is repeated, resulting in a decrease in battery capacity. Further, in the liquid-based battery, there is a concern that the organic electrolytic solution in the battery may ignite and ignite due to a short circuit of the battery due to the formation of dendrites.

Therefore, in recent years, an all-solid-state battery in which all the constituent materials are solid has been attracting attention. The all-solid-state battery has the advantages of excellent cycle characteristics without fear of liquid leakage or ignition, and a high degree of freedom in shape.

As the solid electrolyte used in the all-solid-state lithium secondary battery, that is, the lithium ion conductor, for example, the following are known (see, for example, Non-Patent Documents 1 to 3). Sulfide-based solid electrolytes based on sulfide include Li ₂ SB ₂ S ₃ series (Li ₃ BS ₃ ), Li ₂ SP ₂ S ₅ series (Li ₇ P ₃ S ₁₁ and Li _3). PS ₄ , Li ₈ P ₂ S _{6 and the} like), (Li _4-X Ge _1-X P _X S ₄ ) and the like are known.
However, the solid electrolyte of sulfide system, when exposed to the atmosphere, immediately reacts with moisture in the air, highly toxic hydrogen sulfide (H 2 _S) is generated. Therefore, a battery using a sulfide-based solid electrolyte has a problem in safety.

Therefore, an oxide-based solid electrolyte based on an oxide that is stable without hydrolysis in the atmosphere, does not generate hydrogen sulfide even when exposed to the atmosphere, and has no safety problem has been proposed. There is. As the oxide-based solid electrolyte, LLTO (perovskite), LAGP (NASICON), LLZ (garnet), Li ₃ PO _{4- Li 4} SiO ₄ (LISION) and the like are known (for example, Patent Documents 1 and 2). reference).
However, these oxide-based solid electrolytes require a step of sintering (integrally sintering) at a high temperature in the battery manufacturing process. The step of sintering is a step of laminating each powder material of the negative electrode / solid electrolyte / positive electrode, sintering at about 1,000 ° C., and connecting the grain boundaries of these powders. When firing and sintering at such a high temperature, thermal decomposition and diffusion occur between the electrode active material and the solid electrolyte (for example _{, the interface between LiCoO 2} and LAGP), a high resistance layer is formed, and the entire electrode does not work. There is.
Therefore, there is a demand for a battery that can be manufactured without high-temperature sintering and a positive electrode material used for the battery.

Japanese Unexamined Patent Publication No. 2015-176854 Japanese Unexamined Patent Publication No. 2013-37792

N. Kamaya, K.K. Homma, et al. , (2011), Nat Mater, 10 (9), 682-686 K. Homma, T.M. Yamamoto, et al. , (2013), ECS Transitions, 50 (26), 307-314 M. Tassumisago, R.M. Takano, et al. (2014), Journal of Power Sources, 270 (0), 603-607

An object of the present invention is to provide a battery that can be manufactured without requiring high temperature treatment, a positive electrode material that can be used for the battery, and a method for manufacturing the same.

The means for solving the above-mentioned problems are as follows. That is,
In one embodiment, the positive electrode material is
It has a positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety.
The coating site contains Li and Co,
When EDS elemental analysis was performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co in the coating portion to Co in the positive electrode active material portion (Co in the coating portion / Co in the positive electrode active material portion) was , 0.37 to 0.44.

Further, in one embodiment, the method for producing the positive electrode material is
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coated moiety containing at least a part of the surface of the positive electrode active material moiety and containing Li and Co. Have and
When EDS elemental analysis was performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co in the coating portion to Co in the positive electrode active material portion (Co in the coating portion / Co in the positive electrode active material portion) was , 0.37 to 0.44, which is a method for producing a positive electrode material.
A step of coating at least a part of the surface of the positive electrode active material portion with a solid electrolyte containing Li and moving Co from the positive electrode active material portion to the solid electrolyte to form the coated portion is included. ..

Also, in one aspect, the battery
With the negative electrode
A solid electrolyte layer containing a solid electrolyte containing Li and a solid electrolyte layer
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety and contains Li and Co. When the EDS element analysis is performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co of the coating portion to Co of the positive electrode active material portion (Co of the coating portion / positive electrode active material portion). A positive electrode containing a positive electrode material having a Co) of 0.37 to 0.44,
Have.

Moreover, in one embodiment, the method of manufacturing the battery is
With the negative electrode
A solid electrolyte layer containing a solid electrolyte containing Li and a solid electrolyte layer
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety and contains Li and Co. When the EDS element analysis is performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co of the coating portion to Co of the positive electrode active material portion (Co of the coating portion / positive electrode active material portion). A positive electrode containing a positive electrode material having a Co) of 0.37 to 0.44,
A method of manufacturing a battery, which is a method of manufacturing a battery.
The crimping step of crimping the solid electrolyte layer and the positive electrode material in the positive electrode is included.

As one aspect, it is possible to provide a battery that can be manufactured without requiring high temperature treatment.
Further, as one aspect, it is possible to provide a positive electrode material that can be used for a battery that can be manufactured without requiring high temperature treatment.
Further, as one aspect, it is possible to provide a method for producing a positive electrode material that can be used for a battery that can be produced without requiring high temperature treatment.
Further, as one aspect, it is possible to provide a method for manufacturing a battery that can be manufactured without requiring high temperature treatment.

FIG. 1 is a schematic cross-sectional view showing an example of a positive electrode material. FIG. 2 is a schematic view for explaining a method for producing a positive electrode material. FIG. 3 is a schematic cross-sectional view showing an example of a battery. FIG. 4 is a charge / discharge curve of the second embodiment. FIG. 5 shows a TEM image of a cross section of Example 2 and an elemental analysis (EDS) result. FIG. 6 shows the results of the tensile test after the third charge / discharge in Example 2.

(Positive electrode material)
The disclosed positive electrode material has a positive electrode active material portion and a coating portion.
The coated portion covers at least a part of the surface of the positive electrode active material portion.
The boundary (interface) between the coated portion and the positive electrode active material portion may be clear or unclear.

<Positive electrode active material part>
The positive electrode active material portion means a portion of the positive electrode material in which the positive electrode active material is present.
The positive electrode active material moiety contains a positive electrode active material containing Li, Co, P, and O.
The positive electrode active material is not particularly limited as long as it contains Li, Co, P, and O, and can be appropriately selected depending on the intended purpose. Examples thereof include lithium-containing composite oxides. The lithium-containing composite oxide is not particularly limited as long as it is a composite oxide containing lithium and another metal, and can be appropriately selected depending on the intended purpose. For example, LiCoPO ₄ , Li ₂ CoP ₂ O. _{7 and the} like can be mentioned.
These may be used alone or in combination of two or more.
_{Among these, Li 2} CoP ₂ O ₇ is preferable as the positive electrode active material from the viewpoint that the formation of the coating portion described later can be satisfactorily formed.

The shape of the positive electrode active material portion is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include layered and spherical shapes.
The structure of the positive electrode active material portion is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of forming the coating portion described later, a smooth structure without unevenness is preferable.
The size of the positive electrode active material portion is not particularly limited and can be appropriately selected depending on the intended purpose.

<Covered part>
The coating site contains Li and Co. The coating site further preferably further contains P and O, and more preferably contains a phosphate. The phosphates, _{^{e.g., PO 4 3-, P 2 O}} 7 4-, PO 3 - and the like.
Atomic ratio of Co in the coated part to Co in the positive electrode active material part (Co in the coated part / Co in the positive electrode active material part) when EDS (Energy Dispersive X-ray Spectrometry) elemental analysis was performed on the positive electrode active material part and the coated part. Co) is 0.37 to 0.44.
The atomic ratio of Co in the coating site to Co in the positive electrode active material site can be determined by performing EDS analysis at the time of STEM (Scanning transmission electron microscope) measurement. Specifically, it can be obtained using the following measuring devices and conditions.
STEM measurement conditions Electron microscope: JEM-2100F (manufactured by JEOL Ltd.)
Incident energy: 200 kV
Measurement time: 40s
EDS elemental analysis conditions EDS detector: Silicon drift detector Detection area: 100 mm ²
Electron beam diameter: 1 nm

The shape of the covering portion is not particularly limited and may be appropriately selected depending on the intended purpose.
The structure of the covering portion is not particularly limited and may be appropriately selected depending on the intended purpose, but a smooth structure is preferable.
The size of the covering portion is not particularly limited and can be appropriately selected depending on the intended purpose.

The shape of the positive electrode material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include particulate matter. The particulate form includes, for example, a powder form (atypical shape), a spherical shape, a rectangular parallelepiped shape, and the like.
The structure of the positive electrode material is not particularly limited and may be appropriately selected depending on the intended purpose, and may have a smooth surface or may have grooves.
The size of the positive electrode material is not particularly limited and may be appropriately selected depending on the intended purpose.

FIG. 1 is a schematic cross-sectional view of an example of the disclosed positive electrode material. In the positive electrode material of FIG. 1, the coating portion 2 covers the positive electrode active material portion 1.

(Manufacturing method of positive electrode material)
The disclosed method for producing a positive electrode material is the method for producing the above-mentioned positive electrode material. The method for producing a positive electrode material includes a step of forming a coating portion, and further includes other steps if necessary.

<Step of forming the covering part>
The step of forming the coating portion is a step of coating at least a part of the surface of the positive electrode active material portion with a solid electrolyte containing Li and transferring Co from the positive electrode active material portion to the solid electrolyte.
The method of coating the surface of the positive electrode active material portion with the solid electrolyte is not particularly limited and may be appropriately selected depending on the intended purpose. There is a method of arranging and compressing.
The method for moving Co from the positive electrode active material site to the solid electrolyte is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a heating method. In the heating method, the heating temperature is preferably 300 ° C. to 600 ° C. When the method for coating the solid electrolyte is the vacuum sputtering method, Co can be moved from the positive electrode active material portion to the solid electrolyte by the heat of the film formation.

<< Solid electrolyte >>
The solid electrolyte is not particularly limited as long as it contains Li, and can be appropriately selected depending on the intended purpose. However, an oxide solid electrolyte is preferable from the viewpoint of stability in the atmosphere.
Examples of the oxide-based solid electrolyte include perovskite-type oxides, NASICON-type oxides, LISION-type oxides, and garnet-type oxides. These may be used alone or in combination of two or more.

Examples of the perovskite-type oxide include Li-La-Ti-based perovskite-type oxide represented by _{Li a} La _1-a TiO _{3 and the like, and Li b} La _1-b TaO _{3 and} the like. Examples thereof include Li-La-Ta-based perovskite-type oxides, Li _{-La-Nb-based perovskite-type oxides represented by Li c} La _1-c NbO ₃ , and the like (in the above formula, 0 <a <1). , 0 <b <1, 0 <c <1).

As the NASICON type oxide, for example, _{Li m} X _n Y _o P _p O _q (X in the above formula) _{having a crystal represented by Li 1 + l} Al _l Ti _2-l (PO _{4 ) 3} or the like as a main crystal is used. , B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se, at least one element selected from the group, Y is Ti, Zr, Ge, In, Ga, Sn and It is at least one element selected from the group consisting of Al, and examples thereof include oxides represented by 0 ≦ l ≦ 1, m, n, o, p and q). Be done.

As the LISION type oxide, for example, Li ₄ XO _{4- Li 3} YO ₄ (in the above formula, X is at least one element selected from Si, Ge, and Ti, and Y is P, As. And an oxide represented by at least one element selected from V). Among these, Li ₃ PO ₄ is preferable.

Examples of the garnet-type oxide include Li-La-Zr-based oxides represented by _{lithium lanthanum dilconate (Li 7} La ₃ Zr ₂ O _{12) and the like.}

<Other processes>
The other steps are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a step of forming a positive electrode active material site.
The step of forming the positive electrode active material portion is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a method of depositing and forming a film on an arbitrary substrate by a vacuum sputtering method, a positive electrode active material powder. Examples thereof include a step of forming a green compact of the positive electrode active material by crimping.

An example of the disclosed positive electrode material manufacturing method will be described with reference to the drawings. FIG. 2 is a schematic view in which the positive electrode active material portion 1 is coated with the solid electrolyte 3. Next, the positive electrode active material portion coated with the solid electrolyte is annealed at, for example, 300 ° C., and the cobalt atom is transferred from the positive electrode active material portion to the solid electrolyte. As a result, a positive electrode material having a positive electrode active material moiety containing Li, Co, P, and O, which is coated with a coating moiety containing Li and Co, is obtained. In the case of forming a solid electrolyte by the vacuum sputtering method, Co can be moved from the positive electrode active material portion to the solid electrolyte by the heat of the film formation, so that Co can be transferred from the positive electrode active material portion to the solid electrolyte. There is a possibility that the movement of the solid electrolyte is carried out at the same time as the solid electrolyte is vapor-deposited by the vacuum sputtering method to form a film.

(battery)
The disclosed battery has at least a negative electrode, a solid electrolyte layer, and a positive electrode, and further includes other members, if necessary.
The disclosed batteries are also referred to as all-solid-state batteries.

<Negative electrode>
The negative electrode has, for example, at least a negative electrode active material layer, and, if necessary, other members such as a negative electrode current collector.

<< Negative electrode active material layer >>
The negative electrode active material layer is not particularly limited as long as it is a layer containing the negative electrode active material, and can be appropriately selected depending on the intended purpose.
The negative electrode active material layer may be the negative electrode active material itself.

The negative electrode active material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include lithium, lithium aluminum alloy, amorphous carbon, natural graphite and artificial graphite.

The average thickness of the negative electrode active material layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.05 μm to 3.0 μm, and more preferably 0.1 μm to 2.0 μm.

The method for forming the negative electrode active material layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, sputtering using the target material of the negative electrode active material or compression molding of the negative electrode active material. , A method of depositing the negative electrode active material and the like.

<< Negative electrode current collector >>
The size and structure of the negative electrode current collector are not particularly limited and may be appropriately selected depending on the intended purpose.
Examples of the material of the negative electrode current collector include die steel, gold, indium, nickel, copper, and stainless steel.
Examples of the shape of the negative electrode current collector include a foil shape, a plate shape, and a mesh shape.
Examples of the average thickness of the negative electrode current collector include 10 μm to 500 μm.

<Solid electrolyte layer>
The solid electrolyte layer contains a solid electrolyte containing Li. As the solid electrolyte, the above-mentioned ones can be used.

<Positive electrode>
The positive electrode contains a positive electrode material and, if necessary, other materials such as a positive electrode current collector.
As the positive electrode material, those mentioned above can be used.

<< Positive Electrode Current Collector >>
The size and structure of the positive electrode current collector are not particularly limited and may be appropriately selected depending on the intended purpose.
Examples of the material of the positive electrode current collector include die steel, stainless steel, aluminum, aluminum alloy, titanium alloy, copper, nickel and the like.
Examples of the shape of the positive electrode current collector include a foil shape, a plate shape, and a mesh shape.
Examples of the average thickness of the positive electrode current collector include 10 μm to 500 μm.

<Other parts>
The other member is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a battery case.

<< Battery case >>
The battery case is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a known laminated film that can be used in a conventional all-solid-state battery. Examples of the laminated film include a resin-made laminated film and a film in which a metal is vapor-deposited on a resin-made laminated film.

The shape of the battery is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a cylindrical type, a square type, a button type, a coin type, and a flat type.

FIG. 3 is a schematic cross-sectional view of an example of the disclosed battery. In the battery of FIG. 3, the solid electrolyte layer 12 and the positive electrode 11 are laminated in this order on the negative electrode 13. The positive electrode 11 has a positive electrode active material portion 15 and a coating portion 14. The coating portion 14 exists between the positive electrode active material portion 15 and the solid electrolyte layer 12.

(Battery manufacturing method)
The disclosed battery manufacturing method is the method for manufacturing the above-mentioned battery.
The disclosed battery manufacturing method includes a crimping step and, if necessary, other steps.

<Crimping process>
The crimping step is a step of crimping the solid electrolyte layer and the positive electrode material in the positive electrode.
The crimping method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method of fixing while applying a force with a vise or a clip.

<Other processes>
The other steps are not particularly limited and may be appropriately selected depending on the intended purpose, and examples thereof include a first charge / discharge step.
The first charge / discharge step is a step of charging and discharging a battery immediately after it is manufactured by applying a voltage higher than that during normal charging. Immediately after the manufactured battery, the disclosed battery is in a state in which Co in the positive electrode active material portion is diffused into the solid electrolyte, so that the battery can be operated. By applying a voltage to this battery and charging it, the Co diffusion region in which Co atoms are diffused from the positive electrode active material portion into the solid electrolyte layer increases. This Co diffusion region corresponds to the covering site. The battery thus obtained has a low resistance between the coated portion and the solid electrolyte layer, and the performance is improved as compared with the battery having no coated portion.
The charging voltage in the first charge / discharge step is preferably 3.5 V to 4.5 V when the negative electrode is an LTO substrate. If it is lower than this numerical range, it cannot be charged, and if it is larger than this numerical range, materials such as the positive electrode active material and the solid electrolyte may be damaged and the battery may not function.
The temperature in the first charge / discharge step is preferably 50 ° C to 120 ° C.

(Example 1)
<Manufacturing of positive electrode material>
_{Li 2} CoP ₂ O ₇ was vacuum sputtered at room temperature on a substrate on which Pt / Ti was formed on Si / SiO _{2 at 180 nm / 20 nm.} The formed Li ₂ CoP ₂ O ₇ was annealed at 500 ° C. in an Ar atmosphere for crystallization to obtain _{crystalline Li 2} CoP ₂ O _7.
Next, the _Li 3 PO ₄ solid electrolyte on the crystalline _Li 2 _CoP 2 _{O 7,} in the same manner as Li 2 _CoP 2 _{O 7,} and 100nm deposited at room temperature, to obtain a positive electrode material.

<Analysis of positive electrode material>
A cross section of a portion 100 nm from the surface of the obtained positive electrode material was cut out by FIB (focusing ion beam), and elemental analysis (EDS) was performed. As a result, it was found that the portion 100 nm from the surface of the obtained positive electrode material was Li _4.46 Co _0.37 P ₂ O _7.6 (only the amount of Li was estimated). This indicates that the atomic ratio of Co in the coating site to Co in the positive electrode active material site (Co in the coating site / Co in the positive electrode active material site) is 0.37. The estimated value of Li is a value assuming that the valence of cobalt is 2 and the charge balance of the coated portion is balanced (0 as a whole).
Why the atomic ratio of Co became as described _above, when depositing the _Li 3 PO ₄ solid electrolyte on the Li 2 _CoP 2 _{O 7, Li} 3 PO ₄ was interdiffused _Li 2 _CoP 2 _{O 7} It is thought that this is the case.
Further, when the positive electrode material is manufactured several times in the same manner as described above and analyzed in the same manner, the atomic ratio of Co in the coated portion to Co in the positive electrode active material portion (Co in the coated portion / Co in the positive electrode active material portion) is obtained. , 0.37 to 0.44.

(Example 2)
<Manufacturing of all-solid-state batteries>
_{Li 2} CoP ₂ O ₇ (LCPO), which is a positive electrode active material, was formed by vacuum sputtering at room temperature on a substrate in which Pt / Ti was formed on Si / SiO _{2 at 180 nm / 20 nm.} The formed Li ₂ CoP ₂ O ₇ was annealed at 500 ° C. in an Ar atmosphere for crystallization to obtain _{crystalline Li 2} CoP ₂ O _{7.
A Li 3} PO ₄ solid electrolyte was similarly formed on the crystalline Li ₂ CoP ₂ O ₇ at 100 nm at room temperature. At this time, Li ₃ PO ₄ interdiffused with Li ₂ CoP ₂ O _7, and the composition of the formed 100 nm film was Li _4.46 Co _0.37 P ₂ O _7.6 (estimated only for the amount of Li). (The obtained substrate is designated as substrate 1 (positive electrode side)).
_{Li 4} Ti ₅ O ₁₂ (LTO), which is a negative electrode, is vacuum spattered at room temperature for 100 nm on a substrate on which Pt / Ti is formed on Si / SiO _{2 at} 180 nm / 20 nm, and annealed at 600 ° C. for 1 hour. After crystallization, a _{1 μm film of Li 3} PO ₄ solid electrolyte was formed (the obtained substrate is designated as substrate 2 (negative electrode side)).
The substrate 1 and the substrate 2 were cut so as to have a size of 10 mm × 20 mm. After that, the surface of the substrate 1 on which the coating layer (Li _4.46 Co _0.37 P ₂ O _7.6 ) is present and the surface of the substrate 2 on which the solid electrolyte is present are bonded together by ^{10 mm square (1 cm 2).} rice field. Two of the four corners of the bonded substrate 1 and substrate 2 were fixed with an eyeball clip pole bean mouth width of 20 mm (KOKUYO CLI17) to obtain a battery in a state before charging.

The obtained battery in the state before charging was charged and discharged under the following conditions at 120 ° C. in an Ar atmosphere.
The charging conditions were 1uA CC (constant current charging) up to 4.5V (vs. LTO (Li ₄ Ti ₅ O ₁₂ )) and then 4.5V CV (constant voltage charging). The charging conditions were 0.1uA from beginning to end. ..
The discharge conditions were 1 uAC CC discharge, and the condition was 0.5 V from beginning to end.
After the discharge, the second charge and discharge were performed under the same conditions as above. Further, the charging and discharging were performed for the third time. FIG. 4 shows the charge / discharge curves from the first to the third charge / discharge.
From the obtained charge / discharge curves, it was found that the first charge / discharge curve was different from the second / third charge / discharge curves, and the capacities during charging and discharging were significantly different. This is because lithium diffused between the coating site and Li ₃ PO _4, and the resistance was further reduced from the resistance when only contact was made, resulting in an interfacial connection state equivalent to that of film formation by sputtering. When this dense interface is realized, it becomes possible to discharge at the first discharge.

<Evaluation of cross section of interface>
A cross section of the all-solid-state battery of Example 2 was cut out by FIB, and TEM observation and elemental analysis (EDS) were performed. The results are shown in FIG. 5 and Table 1. In addition, the position No. in Table 1 Indicates a number in FIG. For example, the position No. The ratio of elements of 152 shows the analysis result (ratio of elements) in the frame of 152 in FIG.

<Tensile test>
The battery after the third charge / discharge test was subjected to an apparatus (RSA-G2, manufactured by TA Instruments), and a shear test was conducted in the horizontal direction with respect to the substrate bonding surface. The results are shown in FIG.
As a result, a connection strength of 2,000 g was observed for ^{1 cm 2 of the joint.}

(Comparative Example 1)
A battery was produced in the same manner as in Example 2 except _{that the Li 3} PO ₄ solid electrolyte was not formed on the substrate 1 of Example 2.
At the interface between LCPO without a coating layer and Li ₃ PO ₄ , the resistance was high and the battery could not be operated. Further, a tensile test was conducted in the same manner as in Example 2, and the connection strength was 0 g.

From the results of Example 2 and Comparative Example 2, it was clarified that the battery does not operate as an all-solid-state battery without a coated portion. It is considered that this is because the adhesion between the coating portion and the solid electrolyte layer and the positive electrode active material portion was strong for the following reasons.
As a result of the tensile test, the connection strength of Example 2 was 2,000 g, whereas the connection strength of Comparative Example 1 was 0 g. This means that the adhesion between the respective parts constituting the all-solid-state battery of Example 2 is strong, and it is considered that the covered part plays a particularly large role. It is considered that the adhesion between the positive electrode active material portion, the coating portion and the solid electrolyte layer became stronger by having the coating portion between the positive electrode active material portion and the solid electrolyte layer. It is considered that the reason why the adhesion between the coating portion and the solid electrolyte layer and the positive electrode active material portion became stronger is that the region where Co atoms were diffused from the positive electrode active material portion to the solid electrolyte layer increased.
Further, from the result of TEM observation of the cross section of Example 2, it can be seen that the coated portion, the solid electrolyte layer and the positive electrode active material portion are adhered to each other without forming voids or the like from a microscopic point of view. When a void or the like is formed between the coating portion and the solid electrolyte layer and the positive electrode active material portion, the void acts as a barrier to increase the resistance between the coating portion and the solid electrolyte layer and the positive electrode active material portion, so that the battery can be used as a battery. Performance is reduced. Since the all-solid-state battery of Example 2 has obtained the performance as a battery, it is said that the coating portion, the solid electrolyte layer, and the positive electrode active material portion are firmly adhered to each other without forming voids or the like. Conceivable.

Further, the following additional notes will be disclosed.
(Appendix 1)
It has a positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety.
The coating site contains Li and Co,
When EDS elemental analysis was performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co in the coating portion to Co in the positive electrode active material portion (Co in the coating portion / Co in the positive electrode active material portion) was , 0.37 to 0.44, a positive electrode material.
(Appendix 2)
The positive electrode material according to Appendix 1, wherein the covering portion further contains P and O.
(Appendix 3)
The positive electrode material according to Appendix 1 or 2, wherein the coating site contains a phosphate.
(Appendix 4)
The positive electrode material according to any one of Supplementary note 1 to 3, wherein the positive electrode active material portion _{contains Li 2} CoP ₂ O _7.
(Appendix 5)
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coated moiety containing at least a part of the surface of the positive electrode active material moiety and containing Li and Co. Have and
When EDS elemental analysis was performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co in the coating portion to Co in the positive electrode active material portion (Co in the coating portion / Co in the positive electrode active material portion) was , 0.37 to 0.44, which is a method for producing a positive electrode material.
A step of coating at least a part of the surface of the positive electrode active material portion with a solid electrolyte containing Li and moving Co from the positive electrode active material portion to the solid electrolyte to form the coated portion is included. A method for producing a positive electrode material.
(Appendix 6)
With the negative electrode
A solid electrolyte layer containing a solid electrolyte containing Li and a solid electrolyte layer
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety and contains Li and Co. When the EDS element analysis is performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co of the coating portion to Co of the positive electrode active material portion (Co of the coating portion / positive electrode active material portion). A battery comprising: a positive electrode containing a positive electrode material having a Co) of 0.37 to 0.44.
(Appendix 7)
With the negative electrode
A solid electrolyte layer containing a solid electrolyte containing Li and a solid electrolyte layer
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety and contains Li and Co. When the EDS element analysis is performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co of the coating portion to Co of the positive electrode active material portion (Co of the coating portion / positive electrode active material portion). A positive electrode containing a positive electrode material having a Co) of 0.37 to 0.44,
A method of manufacturing a battery, which is a method of manufacturing a battery.
A method for manufacturing a battery, which comprises a crimping step of crimping the solid electrolyte layer and the positive electrode material at the positive electrode.

1 Positive electrode active material part 2 Coating part 3 Solid electrolyte 4 Cobalt atom 11 Positive electrode 12 Solid electrolyte layer 13 Negative electrode

Claims (7)

It has a positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety.
The coating site contains Li and Co,
When EDS elemental analysis was performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co in the coating portion to Co in the positive electrode active material portion (Co in the coating portion / Co in the positive electrode active material portion) was , 0.37 to 0.44, a positive electrode material. The positive electrode material according to claim 1, wherein the covering portion further contains P and O. The positive electrode material according to claim 1 or 2, wherein the coating site contains a phosphate. The positive electrode material according to any one of claims 1 to 3, _{wherein the positive electrode active material contains Li 2} CoP ₂ O _7. A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coated moiety containing at least a part of the surface of the positive electrode active material moiety and containing Li and Co. Have and
When EDS elemental analysis was performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co in the coating portion to Co in the positive electrode active material portion (Co in the coating portion / Co in the positive electrode active material portion) was , 0.37 to 0.44, which is a method for producing a positive electrode material.
A step of coating at least a part of the surface of the positive electrode active material portion with a solid electrolyte containing Li and moving Co from the positive electrode active material portion to the solid electrolyte to form the coated portion is included. A method for producing a positive electrode material. With the negative electrode
A solid electrolyte layer containing a solid electrolyte containing Li and a solid electrolyte layer
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety and contains Li and Co. When the EDS element analysis is performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co of the coating portion to Co of the positive electrode active material portion (Co of the coating portion / positive electrode active material portion). A battery comprising: a positive electrode containing a positive electrode material having a Co) of 0.37 to 0.44. With the negative electrode
A solid electrolyte layer containing a solid electrolyte containing Li and a solid electrolyte layer
A positive electrode active material moiety containing a positive electrode active material containing Li, Co, P, and O, and a coating moiety that covers at least a part of the surface of the positive electrode active material moiety and contains Li and Co. When the EDS element analysis is performed on the positive electrode active material portion and the coating portion, the atomic ratio of Co of the coating portion to Co of the positive electrode active material portion (Co of the coating portion / positive electrode active material portion). A positive electrode containing a positive electrode material having a Co) of 0.37 to 0.44,
A method of manufacturing a battery, which is a method of manufacturing a battery.
A method for manufacturing a battery, which comprises a crimping step of crimping the solid electrolyte layer and the positive electrode material at the positive electrode.

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