JP7345748B2 - Manufacturing method for secondary batteries - Google Patents

Description

The present invention relates to a method for manufacturing a secondary battery used, for example, in portable electronic devices and electric vehicles.

Lithium-ion secondary batteries have established themselves as high-capacity, lightweight power sources that are essential for mobile devices, electric vehicles, etc. Current lithium ion secondary batteries mainly use flammable organic electrolytes as electrolytes, which raises concerns about the risk of fire. As a method to solve this problem, development of a lithium ion all-solid-state secondary battery using a solid electrolyte in place of an organic electrolyte is underway (for example, see Patent Document 1).

In addition, due to concerns about the worldwide rise in raw material prices for lithium, sodium is also attracting attention as an alternative material to lithium, and sodium ion conductive crystals made of NASICON type Na ₃ Zr ₂ Si ₂ PO ₁₂ are being used as solid electrolytes. A sodium ion all-solid-state battery has been proposed (see, for example, Patent Document 2). In addition, β-alumina (theoretical composition formula: Na ₂ O 11Al ₂ O ₃ ), β''-alumina (theoretical composition formula: Na ₂ O 5.3Al ₂ O ₃ ), Li ₂ O stabilized β'' - Beta such as alumina (Na _1.7 Li _0.3 Al _10.7 O ₁₇ ), MgO stabilized β''-alumina ((Al _10.32 Mg _0.68 O ₁₆ ) (Na _1.68 O)) Alumina-based solid electrolytes and Na ₅ YSi ₄ O ₁₂ are also known to exhibit high sodium ion conductivity, and these solid electrolytes can also be used for sodium ion all-solid-state secondary batteries.

Japanese Patent Application Publication No. 5-205741 Japanese Patent Application Publication No. 2010-15782

The electrode layer and solid electrolyte layer that constitute a secondary battery are usually produced by turning raw material powder into a paste or green sheet, and then firing it. However, such a method has a problem in that it takes a long time to fabricate each layer. Furthermore, it is difficult to produce a layer having a fine structure.

The present invention was made in view of the above-mentioned circumstances, and it is possible to produce electrode layers and solid electrolyte layers that constitute a secondary battery in a short time, and it also makes it possible to produce electrode layers and solid electrolyte layers that have a fine structure. It is an object of the present invention to provide a method that is also capable of producing a solid electrolyte layer.

The method for manufacturing a secondary battery of the present invention is characterized by sintering the powder material and forming an electrode layer or a solid electrolyte layer by irradiating the powder material containing a laser light absorbing component with laser light. do. In this way, the laser light-absorbing component contained in the powder material absorbs the laser light, and the powder material softens and flows, resulting in fusion bonding (sintering). Layers can be created in a short time. Further, by pinpointing a laser beam to a predetermined position, it is also possible to produce an electrode layer or a solid electrolyte layer having a fine structure.

In the method for manufacturing a secondary battery of the present invention, the powder material is preferably an oxide powder.

In the method for manufacturing a secondary battery of the present invention, the laser light absorbing component is preferably at least one selected from transition metal oxides and rare earth element oxides.

In the method for manufacturing a secondary battery of the present invention, the laser light absorbing component is at least one oxide selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Er, Nd, Sm, and Dy. It is preferable that

In the method for producing a secondary battery of the present invention, it is preferable that the powder material contains 0.3 to 70% of a laser light absorbing component in terms of mol% in terms of oxide.

In the method for manufacturing a secondary battery of the present invention, it is preferable that the powder material is glass. In this way, the powder material can be easily softened and fluidized by laser beam irradiation.

In the method for manufacturing a secondary battery of the present invention, the powder material is preferably an electrode active material powder, a solid electrolyte powder, or a solid electrolyte fusion powder.

In the method for manufacturing a secondary battery of the present invention, it is preferable that the wavelength of the laser light is 750 to 1600 nm.

In the method for manufacturing a secondary battery of the present invention, the laser light is preferably a semiconductor laser, a YAG laser, a Yb fiber laser, or a YVO ₄ laser.

The powder material of the present invention is a powder material used to form an electrode layer or a solid electrolyte layer of a secondary battery by irradiating and sintering with laser light, and contains a laser light absorbing component. It is characterized by

According to the manufacturing method of the present invention, it is possible to manufacture electrode layers and solid electrolyte layers that constitute a secondary battery in a short time, and it is also possible to manufacture electrode layers and solid electrolyte layers that have fine structures. It is possible.

The method for manufacturing a secondary battery of the present invention is characterized by sintering the powder material and forming an electrode layer or a solid electrolyte layer by irradiating the powder material containing a laser light absorbing component with laser light. do. For example, oxide powder is used as the powder material.

As the laser light absorption component, at least one oxide selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Er, Nd, Sm and Dy, specifically, TiO ₂ , V Oxidation of transition metal oxides such as ₂ O ₅ , Cr ₂ O ₃ , MnO, FeO, CoO, NiO, CuO, and rare earth elements such as Er ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Dy ₂ O ₃ Things can be mentioned. These can be used alone or in combination of two or more. Among these, CuO, FeO, or NiO, which have excellent laser light absorption ability, are preferred.

The powder material preferably contains 0.3 to 70%, 0.5 to 60%, particularly 1 to 50% of a laser light absorbing component in terms of mole % in terms of oxide. If the content of the laser light-absorbing component is too small, the laser light cannot be absorbed sufficiently, so the powder material does not soften and flow, which tends to make it difficult to fabricate electrode layers and solid electrolyte layers. On the other hand, even if the content of the laser light absorbing component is too large, the powder material is difficult to soften and flow. Furthermore, as will be described later, when the powder material is used as a functional powder such as an electrode active material powder or a solid electrolyte powder, there is a possibility that the performance of the functional powder may not be obtained.

The average particle diameter of the powder material is preferably 0.01 to 15 μm, 0.05 to 12 μm, particularly 0.1 to 10 μm. If the average particle diameter of the powder material is too small, the cohesive force between the powder materials becomes strong and the dispersibility tends to be poor when formed into a paste. As a result, it becomes difficult to obtain a homogeneous electrode layer or solid electrolyte layer. As a result, problems may occur, such as the internal resistance of the battery becoming larger and the operating voltage tending to decrease, or the electrode density decreasing and the capacity per unit volume of the battery decreasing. On the other hand, if the average particle diameter of the powder material is too large, the density and surface smoothness of the electrode layer and solid electrolyte layer tend to be poor. Furthermore, when the powder material is an electrode active material powder, ion diffusivity tends to decrease and internal resistance increases.

In the present invention, the average particle diameter means D ₅₀ (volume-based average particle diameter), and refers to a value measured by a laser diffraction scattering method.

Powder materials include glass or ceramics. When the powder material is glass, it has a relatively low softening point, so it can be easily softened and fluidized by irradiation with laser light.

The powder material can take the form of, for example, an electrode active material powder (including an electrode active material precursor glass powder before crystallization), a solid electrolyte powder, or a solid electrolyte fusion powder. Hereinafter, various embodiments mainly related to sodium ion secondary batteries will be described in detail. The present invention can also be applied to electrode active material powder, solid electrolyte powder, solid electrolyte fusion powder for lithium ion secondary batteries, etc., as long as the powder material contains the above-mentioned laser light absorbing component. .

(1) When the powder material is an electrode active material powder The positive electrode active material powder includes, for example, at least one of phosphates, silicates, and borates, and is capable of occluding and releasing sodium; Examples include those containing 8 to 55% of Na ₂ O, 10 to 70% of CrO+FeO+MnO+CoO+NiO, and 15 to 70% of P ₂ O ₅ +SiO ₂ +B ₂ O ₃ in terms of mol% in oxide terms. The reason why each component is limited in this way will be explained below. In addition, in the description regarding the content of each component below, unless otherwise specified, "%" means "mol%". Moreover, in this specification, "○+○+..." means the total amount of each corresponding component.

Na ₂ O serves as a source of sodium ions that move between the positive electrode active material and the negative electrode active material during charging and discharging. The content of Na ₂ O is preferably 8 to 55%, 15 to 45%, particularly 25 to 35%. If there is too little Na ₂ O, there will be fewer sodium ions that contribute to occlusion and release, and the discharge capacity will tend to decrease. On the other hand, if there is too much Na ₂ O, foreign crystals such as Na ₃ PO ₄ that do not contribute to charging and discharging tend to precipitate, so that the discharge capacity tends to decrease.

CrO, FeO, MnO, CoO, and NiO are laser light absorbing components. In addition, the valence of each transition element changes during charging and discharging, causing a redox reaction, thereby acting as a driving force for storing and releasing sodium ions. Among them, NiO and MnO have a large effect of increasing the redox potential. Moreover, FeO is particularly easy to stabilize the structure during charging and discharging, and is easy to improve cycle characteristics. The content of CrO+FeO+MnO+CoO+NiO is preferably 10-70%, 15-60%, 20-55%, 23-50%, 25-40%, particularly 26-36%. If CrO+FeO+MnO+CoO+NiO is too small, redox reactions accompanying charging and discharging become difficult to occur, and fewer sodium ions are occluded and released, which tends to reduce discharge capacity. In addition, the laser light absorption ability is poor, and there is a possibility that the powder material will not be sufficiently softened and fluidized when irradiated with laser light. On the other hand, if there is too much CrO+FeO+MnO+CoO+NiO, foreign crystals tend to precipitate and the discharge capacity decreases.

Since P ₂ O ₅ , SiO ₂ and B ₂ O ₃ form a three-dimensional network structure, they have the effect of stabilizing the structure of the positive electrode active material. In particular, P ₂ O ₅ and SiO ₂ are preferred because they have excellent ionic conductivity, and P ₂ O ₅ is most preferred. The content of P ₂ O ₅ +SiO ₂ +B ₂ O ₃ is 15 to 70%, preferably 20 to 60%, particularly 25 to 45%. If P ₂ O ₅ +SiO ₂ +B ₂ O ₃ is too small, the discharge capacity tends to decrease during repeated charging and discharging. On the other hand, if P ₂ O ₅ +SiO ₂ +B ₂ O ₃ is too large, foreign crystals such as P ₂ O ₅ that do not contribute to charging and discharging tend to precipitate. The content of each component of P ₂ O ₅ , SiO ₂ and B ₂ O ₃ is preferably 0 to 70%, 15 to 70%, 20 to 60%, particularly 25 to 45%.

Further, vitrification can be facilitated by containing various components in addition to the above components within a range that does not impair the effect as a positive electrode active material. Such components include MgO, CaO, SrO, BaO, ZnO, CuO, Al ₂ O ₃ , GeO ₂ , Nb ₂ O ₅ , ZrO ₂ , and Sb ₂ O ₅ in oxide notation, and in particular, network formation Al ₂ O ₃ which acts as an oxide and V ₂ O ₅ which serves as an active material component are preferable. The total content of the above components is preferably 0 to 30%, 0.1 to 20%, particularly 0.5 to 10%.

The negative electrode active material powder is particularly one that contains at least one of phosphate, silicate, and borate and is capable of absorbing and desorbing sodium, specifically, SnO 0 to 0 in terms of mol% in terms of oxide. 90%, Bi ₂ O ₃ 0-90%, Nb ₂ O ₅ 0-90%, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO + FeO + CoO + NiO + CuO + Er ₂ O ₃ +Nd ₂ O ₃ +Sm ₂ O ₃ +Dy ₂ O ₃ 0. 3 70%, SiO ₂ +B ₂ O ₃ +P ₂ O ₅ 5-75%, and Na ₂ O 0-80%. With the above configuration, a structure is formed in which the negative electrode active material components Sn ions, Bi ions, Ti ions, Fe ions, or Nb ions are more uniformly dispersed in the oxide matrix containing Si, B, or P. Ru. Moreover, by containing Na ₂ O, the material becomes even more excellent in sodium ion conductivity. As a result, it is possible to suppress the volume change when occluding and releasing sodium ions, and it is possible to obtain a negative electrode active material with even better cycle characteristics.

The reason why the composition of the negative electrode active material powder is limited as described above will be explained below.

SnO, Bi ₂ O ₃ and Nb ₂ O ₅ are negative electrode active material components that serve as sites for occluding and releasing alkali ions. By containing these components, the discharge capacity per unit mass of the negative electrode active material becomes larger, and the charge/discharge efficiency (ratio of discharge capacity to charge capacity) at the time of initial charge/discharge is more likely to be improved. However, if the content of these components is too large, the volume change accompanying storage and release of sodium ions during charging and discharging cannot be alleviated, and cycle characteristics tend to deteriorate. In view of the above, it is preferable that the content range of each component is as follows.

The content of SnO is preferably 0 to 90%, 45 to 85%, 55 to 75%, particularly 60 to 72%.

The content of Bi ₂ O ₃ is preferably 0 to 90%, 10 to 70%, 15 to 65%, particularly 25 to 55%.

The content of Nb ₂ O ₅ is preferably 0 to 90%, 7 to 79%, 9 to 69%, 11 to 59%, 13 to 49%, particularly 15 to 39%. Note that SnO+Bi ₂ O ₃ +Nb ₂ O ₅ is preferably 0 to 90%, 5 to 85%, particularly 10 to 80%.

TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO, FeO, CoO, NiO, CuO, Er ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ and Dy ₂ O ₃ are laser light absorbing components. Further, like SnO, Bi ₂ O ₃ and Nb ₂ O ₅ , these components can function as negative electrode active material components that serve as sites for occluding and releasing alkali ions. The content of TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd ₂ O ₃ +Sm ₂ O ₃ +Dy ₂ O ₃ is 0.3 to 70%, 0.5 to 60%, especially 1 to 50%. It is preferable that there be. If the content of these components is too small, the laser light cannot be absorbed sufficiently, so that the negative electrode active material powder (powder material) does not soften and flow, which tends to make it difficult to prepare the electrode layer. On the other hand, if the content of these components is too large, the negative electrode active material powder tends to not soften and flow, making it difficult to prepare the electrode layer. Moreover, there is a possibility that the performance as a negative electrode active material may not be obtained.

SiO ₂ , B ₂ O ₃ and P ₂ O ₅ are network-forming oxides that surround the sodium ion occlusion and release sites in the negative electrode active material component and have the effect of further improving cycle characteristics. Among them, SiO ₂ and P ₂ O ₅ not only further improve the cycle characteristics but also have excellent sodium ion conductivity, so they have the effect of further improving the rate characteristics.

SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is preferably 5 to 85%, 6 to 79%, 7 to 69%, 8 to 59%, 9 to 49%, particularly 10 to 39%. If SiO ₂ + B ₂ O ₃ + P ₂ O ₅ is too small, the volume change of the negative electrode active material component due to occlusion and release of sodium ions during charging and discharging cannot be alleviated, resulting in structural destruction, which tends to deteriorate cycle characteristics. Become. On the other hand, when SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is too large, the content of the negative electrode active material component tends to be relatively small, and the charge/discharge capacity per unit mass of the negative electrode active material tends to be small.

In addition, the preferable range of each content _{of SiO2} , _{B2O3 ,} and _P2O5 is as follows.

The content of SiO ₂ is preferably 0 to 75%, 5 to 75%, 7 to 60%, 10 to 50%, 12 to 40%, particularly 20 to 35%. If the content of SiO ₂ is too large, the discharge capacity tends to decrease.

The content of P ₂ O ₅ is preferably 5 to 75%, 7 to 60%, 10 to 50%, 12 to 40%, particularly 20 to 35%. If the content of P ₂ O ₅ is too low, it will be difficult to obtain the above effects. On the other hand, if the content of P ₂ O ₅ is too high, the discharge capacity will tend to decrease, and the water resistance will also tend to decrease. Further, when a water-based electrode paste is produced, undesired foreign crystals are generated and the P ₂ O ₅ network is cut, so that cycle characteristics tend to deteriorate.

The content of B ₂ O ₃ is preferably 0 to 75%, 5 to 75%, 7 to 60%, 10 to 50%, 12 to 40%, particularly 20 to 35%. If the content of B ₂ O ₃ is too high, the discharge capacity will tend to decrease, and the chemical durability will also tend to decrease.

Na ₂ O is a component that improves the initial discharge capacity by making it difficult for sodium ions to be absorbed into the negative electrode active material during initial charging. It also has the effect of increasing sodium ion conductivity and lowering the operating voltage of the negative electrode. The content of Na ₂ O is preferably 0 to 80%, 1 to 70%, particularly 5 to 60%. If the content of Na ₂ O is too high, a large amount of heterogeneous crystals (Na ₄ P ₂ O ₇ , NaPO _{4 ,} etc.) containing sodium ions are formed, and the cycle characteristics tend to deteriorate. Furthermore, since the content of the active material component becomes relatively small, the discharge capacity tends to decrease.

Note that the electrode active material powder may be mixed with a conductive additive such as solid electrolyte powder or carbon powder, which will be described later, and used as an electrode mixture.

(2) When the powder material is a solid electrolyte powder As a solid electrolyte powder, Na ₂ O 1-80%, SiO ₂ +B ₂ O ₃ +P ₂ O ₅ 1-80%, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd _{2 O 3 +Sm 2 O 3} + _{Dy 2} O ₃ 0.3 to 70%. The reason why each component is limited in this way will be explained below.

Na ₂ O is a component that increases sodium ion conductivity. The content of Na ₂ O is preferably 1 to 80%, 5 to 70%, particularly 10 to 60%. The content of Na ₂ O is preferably 0 to 80%, 1 to 70%, particularly 5 to 60%. If the content of Na ₂ O is too low, sodium ion conductivity tends to be poor. On the other hand, if the content of Na ₂ O is too high, the sodium ion conductivity tends to be rather poor.

SiO ₂ , B ₂ O ₃ and P ₂ O ₅ are network-forming oxides, and are components that enhance the softening fluidity of the solid electrolyte powder. It also has the effect of improving sodium ion conductivity. SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is preferably 1 to 80%, 5 to 79%, 10 to 79%, particularly 20 to 69%. If SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is too small, it tends to become difficult to soften and flow, and chemical durability tends to decrease. On the other hand, if the content of SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is too large, sodium ion conductivity tends to decrease.

The content of each component of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ should be 0 to 80%, 1 to 80%, 5 to 79%, 10 to 79%, especially 20 to 69%. is preferred.

TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO, FeO, CoO, NiO, CuO, Er ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ and Dy ₂ O ₃ are laser light absorbing components. The content of TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd ₂ O ₃ +Sm ₂ O ₃ +Dy ₂ O ₃ is 0.3 to 70%, 0.5 to 60%, especially 1 to 50%. It is preferable that there be. If the content of these components is too small, laser light cannot be absorbed sufficiently, so the solid electrolyte powder (powder material) does not soften and flow, which tends to make it difficult to produce a solid electrolyte layer. On the other hand, if the content of these components is too large, the solid electrolyte powder tends to not soften and flow, making it difficult to produce a solid electrolyte layer. Furthermore, there is a possibility that the performance as a solid electrolyte may not be obtained.

(3) When the powder material is a solid electrolyte fusion powder The solid electrolyte fusion powder contains 0 to 80% Na ₂ O, SiO ₂ + B ₂ O ₃ + P ₂ O ₅ 1 to 80% in terms of oxide mole%. 80%, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd ₂ O ₃ +Sm ₂ O ₃ +Dy ₂ O ₃ 0.3 to 70%. The reason why each component is limited in this way will be explained below.

Na ₂ O is a component that increases sodium ion conductivity. The content of Na ₂ O is preferably 0 to 80%, 1 to 80%, 5 to 70%, particularly 10 to 60%. Even if the content of Na ₂ O is too high, the sodium ion conductivity tends to be rather poor.

SiO ₂ , B ₂ O ₃ and P ₂ O ₅ are network-forming oxides, and are components that enhance the softening fluidity of the powder for solid electrolyte fusion. It also has the effect of improving sodium ion conductivity. SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is preferably 1 to 80%, 5 to 79%, 10 to 79%, particularly 20 to 69%. If SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is too small, it tends to become difficult to soften and flow, and chemical durability tends to decrease. On the other hand, if the content of SiO ₂ +B ₂ O ₃ +P ₂ O ₅ is too large, sodium ion conductivity tends to decrease.

The content of each component of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ should be 0 to 80%, 1 to 80%, 5 to 79%, 10 to 79%, especially 20 to 69%. is preferred.

TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO, FeO, CoO, NiO, CuO, Er ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ and Dy ₂ O ₃ are laser light absorbing components. The content of TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd ₂ O ₃ +Sm ₂ O ₃ +Dy ₂ O ₃ is 0.3 to 70%, 0.5 to 60%, especially 1 to 50%. It is preferable that there be. If the content of these components is too low, the laser light cannot be absorbed sufficiently, so the solid electrolyte fusion powder (powder material) will not soften and flow, making it difficult to create a solid electrolyte layer. . On the other hand, if the content of these components is too large, the solid electrolyte fusion powder does not soften and flow, and it tends to be difficult to prepare a solid electrolyte layer.

It is preferable that the laser beam has a wavelength in the near-infrared region to the infrared region, specifically, a wavelength of 750 to 1,600 nm, 900 to 1,400 nm, 950 to 1,200 nm, and especially 1,000 to 1,100 nm because it is easily absorbed by the laser light absorption component.

The laser beam is preferably one that can irradiate light with a wavelength in the above range, and includes, for example, a semiconductor laser, a YAG laser, a Yb fiber laser, and a YVO ₄ laser.

Note that the powder material may be crystallized by firing at a predetermined temperature and atmosphere as necessary after the laser beam irradiation.

Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited to these Examples.

(Examples 1-1 to 1-11: Examples in which the powder material is positive electrode active material precursor glass powder)
(a) Preparation of positive electrode active material precursor powder Table 1 shows Examples 1-1 to 1-11.

A raw material batch was prepared to have the composition shown in Table 1. Raw materials include sodium carbonate (Na ₂ CO ₃ ), sodium metaphosphate (NaPO ₃ ), sodium dihydrogen phosphate (NaH ₂ PO ₄ ), liquid phosphoric acid (H ₃ PO ₄ ), nickel oxide (NiO), and Iron acid (FeC ₂ O ₄ ), manganese oxide (MnO), magnesium oxide (MgO) or silica (SiO ₂ ) were used. The raw material batch was placed in a graphite crucible and melted at 1200° C. for 1 hour in a nitrogen atmosphere, and the resulting molten glass was poured into a water-cooled roller and rapidly cooled to obtain a film-like glass. A positive electrode active material precursor glass powder (powder material) having an average particle diameter _D50 of 0.6 μm was obtained by pulverizing the film-like glass with a ball mill. In this example, the laser light absorbing components in the powder material are NiO, FeO, and MnO.

(b) Preparation of solid electrolyte powder Solid electrolyte powder with an average particle size of 2.5 μm was obtained by crushing β''-alumina or NASICON crystal (Na ₃ Zr ₂ PSi ₂ O ₁₂ ) with a ball mill and air classification. Ta.

(c) Preparation of positive electrode composite material paste A positive electrode composite material was obtained by mixing a positive electrode active material precursor glass powder, a solid electrolyte powder, and acetylene black as a conductive additive in a mass ratio of 71:25:4. To 100 parts by mass of the positive electrode composite material, 10 parts by mass of polypropylene carbonate (PPC) is added as a binder, and N-methylpyrrolidone is used as a solvent so that the solid content concentration (total amount of the positive electrode composite material and binder) is 60% by mass. A positive electrode composite paste was prepared by adding and kneading the mixture as follows.

(d) Formation of positive electrode composite layer The positive electrode composite paste was placed on a 0.5 mm thick solid electrolyte layer (solid electrolyte sheet) made of the same material as the solid electrolyte powder used in the positive electrode composite material, and a 4 mm long wire A positive electrode composite material layer was formed by printing and coating to have a width of 0.8 mm and a thickness of 70 μm. After removing the binder and solvent from the positive electrode composite layer by baking it in the air at 350° C. for 1 hour, it was irradiated with laser light under the conditions listed in Table 1 using a Yb fiber laser with a wavelength of 1080 nm. SEM (scanning electron microscopy) observation shows that the glass powder, which is a positive electrode active material precursor, is softened and fluidized by laser light, and the positive electrode composite materials and the positive electrode composite layer and solid electrolyte layer are fused and bonded. Those in which it was confirmed that the positive electrode active material precursor glass powder was not softened and flowed and were not fused and bonded were evaluated as "fail".

(e) Preparation of test battery The positive electrode composite layer was fired under the crystallization conditions listed in Table 1 to crystallize the positive electrode active material precursor in the positive electrode composite layer to obtain a positive electrode active material. Table 1 shows the results of identifying the positive electrode active material crystals in the positive electrode composite material layer using an X-ray diffraction apparatus. In addition to the positive electrode active material crystals, crystals derived from the solid electrolyte were confirmed in all samples.

After forming a metal aluminum thin film as a current collector on the surface of the positive electrode composite layer by sputtering, metallic sodium was pasted on the surface of the solid electrolyte layer opposite to the surface on which the positive electrode composite layer was formed to form a CR2032 type test battery. was created. When the test battery was subjected to a charge/discharge test, it was confirmed that it worked.

(Examples 2-1 to 2-10: Examples in which the powder material is positive electrode active material precursor crystal powder)
Table 2 shows Examples 2-1 to 2-10.

(a) Preparation of positive electrode active material powder A raw material batch was prepared to have the composition shown in Table 2, and film glass was obtained in the same manner as in Examples 1-1 to 1-11. Film glass is pre-crystallized at 500 to 600°C in an inert atmosphere of nitrogen or argon, or a mixed gas atmosphere of hydrogen and an inert gas, and then pulverized with a ball mill to reduce the average particle size _D50 to 0. .8 μm positive electrode active material precursor crystal powder (powder material) was obtained. In this example, the laser light absorbing components in the powder material are NiO, FeO, and MnO.

(b) Preparation of solid electrolyte powder NASICON crystal (Na ₃ Zr ₂ PSi ₂ O ₁₂ ) was ground in a ball mill and air classified to obtain a solid electrolyte powder with an average particle size of 2.5 μm.

(c) Preparation of positive electrode composite paste Examples 1-1 to 1- except that the positive electrode active material precursor crystal powder obtained in (a) above was used instead of the positive electrode active material precursor glass powder. A positive electrode composite paste was prepared in the same manner as in Example 11.

(d) Formation of positive electrode composite layer The positive electrode composite paste was placed on a 0.5 mm thick solid electrolyte layer (solid electrolyte sheet) made of the same material as the solid electrolyte powder used in the positive electrode composite material, and a 4 mm long wire A positive electrode composite material layer was formed by printing and coating to have a width of 0.8 mm and a thickness of 70 μm. After removing the binder and solvent from the positive electrode composite layer by baking it in the air at 350° C. for 1 hour, it was irradiated with laser light under the conditions listed in Table 2 using a Yb fiber laser with a wavelength of 1080 nm. In each example, the positive electrode active material precursor crystal powder is melted by laser irradiation and becomes amorphous, and the positive electrode composite materials and the positive electrode composite layer and solid electrolyte layer are fused and bonded. was confirmed.

(e) Preparation of test battery The positive electrode composite material layer was fired under the crystallization conditions listed in Table 2. As a result, the positive electrode active material precursor crystal powder, which had been melted and amorphized by laser irradiation, was crystallized to form a positive electrode active material. Table 2 shows the results of identifying the positive electrode active material crystals in the positive electrode composite material layer using an X-ray diffraction device. In addition to the positive electrode active material crystals, crystals derived from the solid electrolyte were confirmed in all samples.
Thereafter, test batteries were prepared in the same manner as in Examples 1-1 to 1-11, and when a charge/discharge test was performed, it was confirmed that they worked.

(Examples 3-1 to 3-2: Examples in which the powder material is negative electrode active material powder)
Table 3 shows Examples 3-1 to 3-2.

(a) Preparation of negative electrode active material powder A raw material batch was prepared to have the composition shown in Table 3. Raw materials include sodium carbonate (Na ₂ CO ₃ ), bismuth oxide (Bi ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), copper oxide (CuO), boron oxide (B ₂ O ₃ ), or silica (SiO ₂ )It was used. A raw material batch was placed in a platinum crucible and melted at 1100° C. for 1 hour, and the resulting molten glass was poured into a water-cooled roller and rapidly cooled to obtain a film-like glass. A negative electrode active material powder (powder material) having an average particle diameter _D50 of 0.8 μm was obtained by pulverizing the film-like glass with a ball mill. In this example, the laser light absorbing components in the powder material are Er ₂ O ₃ and CuO.

(b) Preparation of solid electrolyte powder β''-alumina was ground in a ball mill and air classified to obtain a solid electrolyte powder with an average particle size of 2.5 μm.

(c) Preparation of negative electrode composite material paste A negative electrode composite material was obtained by mixing negative electrode active material powder, solid electrolyte powder, and acetylene black as a conductive additive in a mass ratio of 89:10:1. To 100 parts by mass of the negative electrode composite material, 7 parts by mass of polypropylene carbonate was added as a binder, and N-methylpyrrolidone was added as a solvent so that the solid content concentration (total amount of negative electrode composite material and binder) was 65% by mass. A negative electrode composite material paste was prepared by kneading the mixture.

(d) Formation of negative electrode composite material layer A negative electrode composite material paste is placed on a 0.5 mm thick solid electrolyte layer (solid electrolyte sheet) made of the same material as the solid electrolyte powder used in the negative electrode composite material, and a 4 mm long wire A negative electrode composite layer was formed by printing and coating to a width of 0.8 mm and a thickness of 70 μm. The negative electrode composite layer was baked in the air at 320°C for 1 hour to remove the binder and organic solvent, and then irradiated with laser light under the conditions listed in Table 3 using a Yb fiber laser with a wavelength of 1080 nm. . In each of the examples, it was confirmed that the negative electrode active material powder melted and flowed due to laser irradiation, and the negative electrode composite materials and the negative electrode composite material layer and the solid electrolyte layer were fused and bonded. In addition, as a result of identifying the crystals in the negative electrode composite material layer using an X-ray diffraction device, it was confirmed that the negative electrode active material was amorphous in all samples, and crystals derived from the solid electrolyte powder were confirmed. Ta.

(e) Preparation of test battery After forming a metal aluminum thin film as a current collector on the surface of the negative electrode composite layer by sputtering, metallic sodium A CR2032 type test battery was prepared. When the test battery was subjected to a charge/discharge test, it was confirmed that it worked.

(Examples 4-1 to 4-3: Examples in which the powder material is a powder for solid electrolyte fusion)
Table 4 shows Examples 4-1 to 4-3.

(a) Preparation of Solid Electrolyte Fusion Powder A raw material batch was prepared to have the composition shown in Table 4, and film glass was obtained in the same manner as in Examples 1-1 to 1-11. A solid electrolyte fusion powder (powder material) having an average particle diameter _D50 of 1.5 μm was obtained by pulverizing the film-like glass with a ball mill. In this example, the laser light absorbing component in the powder material is CuO.

(b) Preparation of solid electrolyte powder NASICON crystal (Na ₃ Zr ₂ PSi ₂ O ₁₂ ) was ground in a ball mill and air classified to obtain a solid electrolyte powder with an average particle size of 2.5 μm.

(c) Preparation of solid electrolyte mixture paste A solid electrolyte mixture was prepared by mixing solid electrolyte powder and solid electrolyte fusion powder at a mass ratio of 72:28. To 100 parts by mass of the solid electrolyte mixture, 10 parts by mass of polypropylene carbonate was added as a binder, and N-methylpyrrolidone was added as a solvent so that the solid content concentration (total amount of solid electrolyte mixture and binder) was 70% by mass. A solid electrolyte mixture paste was prepared by adding the mixture to the solid electrolyte mixture and kneading it.

(d) Preparation of positive electrode composite material layer The positive electrode composite material paste prepared in Examples 1-1 to 1-11 was applied to a thickness of 100 μm on a polyethylene terephthalate (PET) sheet, and dried in the air at 80°C for 1 hour. A positive electrode composite green sheet was prepared. After pressing the positive electrode composite green sheet, cutting it into a size of 45 mm x 45 mm and releasing it from the PET sheet, it is crystallized by firing at 500°C in an atmosphere of H ₂ /N ₂ = 4/96 (volume %). A positive electrode composite material layer (positive electrode composite material sheet) was prepared.

(e) Formation of solid electrolyte composite material layer Solid electrolyte composite material paste was applied to the surface of the positive electrode composite material layer in the form of 30 columns x 2 rows of lines with a length of 20 mm, a line width of 0.8 mm, and a thickness of 150 μm, with an interval of 0.5 mm. A solid electrolyte composite material layer was formed by printing and coating in a lined manner. After drying the solid electrolyte composite layer in the air at 80°C and baking it in nitrogen at 350°C to remove the binder and organic solvent, it was exposed to laser light under the conditions listed in Table 4 using a Yb fiber laser with a wavelength of 1080 nm. was irradiated. In each example, it was confirmed that the solid electrolyte fusion powder softened and flowed due to laser irradiation, and the solid electrolyte composite materials and the positive electrode composite material layer and the solid electrolyte composite material layer were fused and bonded. It was done.

(f) Preparation of test battery After forming a metal aluminum thin film as a current collector on the surface of the positive electrode composite layer by sputtering, the surface of the solid electrolyte composite layer opposite to the surface on which the positive electrode composite layer was formed A CR2032 type test battery was prepared by pasting metallic sodium onto the battery. When the test battery was subjected to a charge/discharge test, it was confirmed that it worked.

(Examples 5-1 to 5-3: Examples in which the powder material is solid electrolyte powder)
Table 5 shows Examples 5-1 to 5-3.

(a) Production of solid electrolyte powder The solid electrolyte fusion powders produced in Examples 4-1 to 4-3 were used as the solid electrolyte powder (powder material) in this example.

(b) Preparation of solid electrolyte paste 10 parts by mass of polypropylene carbonate as a binder was added to 100 parts by mass of solid electrolyte powder, and N-methylpyrrolidone was added as a solvent until the solid content concentration (total amount of solid electrolyte powder and binder) was adjusted to 100 parts by mass. A solid electrolyte paste was prepared by adding it to a concentration of 70% by mass and kneading it.

(c) Preparation of positive electrode composite material layer The positive electrode composite material layers (positive electrode composite material sheets) produced in Examples 4-1 to 4-3 were used.

(d) Formation of solid electrolyte layer The positive electrode mixture was prepared in the same manner as in Examples 4-1 to 4-3, except that the solid electrolyte paste prepared in (b) above was used instead of the solid electrolyte mixture paste. A solid electrolyte layer was formed on the layer. After drying the solid electrolyte composite layer in the air at 80°C and baking it in nitrogen at 350°C to remove the binder and organic solvent, it was exposed to laser light under the conditions listed in Table 5 using a Yb fiber laser with a wavelength of 1080nm. was irradiated. In each of the examples, it was confirmed that the solid electrolyte powders were softened and fluidized by laser irradiation, and the solid electrolyte powders and the positive electrode composite layer and the solid electrolyte layer were fused and bonded.

(e) Production of test batteries Test batteries were produced in the same manner as in Examples 4-1 to 4-3, and a charge/discharge test was conducted, and it was confirmed that they worked.

(Comparative Example 6-1: Comparative example where the powder material is positive electrode active material precursor glass powder)
Table 6 shows Comparative Example 6-1.

(a) Preparation of positive electrode active material precursor glass powder A raw material batch was prepared to have the composition shown in Table 6, and a positive electrode with an average particle diameter _D50 of 0.8 μm was prepared in the same manner as in Examples 1-1 to 1-11. An active material precursor glass powder (powder material) was obtained. In this example, the powder material does not contain a laser light absorbing component.

(b) Preparation of solid electrolyte powder NASICON crystal (Na ₃ Zr ₂ PSi ₂ O ₁₂ ) was ground in a ball mill and air classified to obtain a solid electrolyte powder with an average particle size of 2.5 μm.

(c) Preparation of positive electrode composite paste Using the positive electrode active material precursor glass powder obtained in (a) above, positive electrode composite pastes were produced in the same manner as in Examples 1-1 to 1-11.

(d) Formation of positive electrode composite layer The positive electrode composite paste was placed on a 0.5 mm thick solid electrolyte layer (solid electrolyte sheet) made of the same material as the solid electrolyte powder used in the positive electrode composite material, and a 4 mm long wire A positive electrode composite material layer was formed by printing and coating to have a width of 0.8 mm and a thickness of 70 μm. After removing the binder and solvent from the positive electrode composite layer by baking it in the air at 350° C. for 1 hour, it was irradiated with laser light under the conditions listed in Table 6 using a Yb fiber laser with a wavelength of 1080 nm. As a result, the positive electrode active material precursor glass powder was not melted by laser irradiation, and the positive electrode composite materials and the positive electrode composite material layer and the solid electrolyte layer were not fused and bonded.

(Comparative Examples 7-1 to 7-2: Comparative examples where the powder material is negative electrode active material powder)
Table 7 shows Comparative Examples 7-1 and 7-2.

(a) Preparation of negative electrode active material powder A raw material batch was prepared to have the composition shown in Table 7, and a negative electrode active material having an average particle diameter _D50 of 0.8 μm was prepared in the same manner as in Examples 3-1 to 3-3. A powder (powder material) was obtained. In this example, the powder material does not contain a laser light absorbing component.

(b) Preparation of solid electrolyte powder β''-alumina was ground in a ball mill and air classified to obtain a solid electrolyte powder with an average particle size of 2.5 μm.

(c) Preparation of negative electrode composite paste A negative electrode composite paste was produced in the same manner as in Examples 3-1 to 3-3 using the above negative electrode active material powder and solid electrolyte powder.

(d) Formation of negative electrode composite material layer Using the above negative electrode composite material paste, the same material as the solid electrolyte powder used in the negative electrode composite material was made in the same manner as in Examples 3-1 to 3-3 to a thickness of 0.5 mm. A negative electrode composite material layer was formed on the solid electrolyte layer (solid electrolyte sheet).

Next, the surface of the negative electrode composite material layer was irradiated with laser light under the conditions listed in Table 7 using a Yb fiber laser with a wavelength of 1080 nm. As a result, the negative electrode active material powder was not melted by laser irradiation, and the negative electrode composite materials and the negative electrode composite material layer and the solid electrolyte layer were not fused and bonded.

(Comparative Example 8-1: Comparative example where the powder material is a powder for solid electrolyte fusion)
Table 8 shows Comparative Example 8-1.

(a) Preparation of powder for solid electrolyte fusion A raw material batch was prepared to have the composition shown in Table 8, and film glass was obtained in the same manner as in Examples 1-1 to 1-11. A solid electrolyte fusion powder (powder material) having an average particle diameter _D50 of 1.5 μm was obtained by pulverizing the film-like glass with a ball mill. In this example, the powder material does not contain a laser light absorbing component.

(b) Preparation of solid electrolyte powder Solid electrolyte powder with an average particle diameter of 2.5 μm was obtained by pulverizing β'' alumina with a ball mill and air classification.

(c) Preparation of solid electrolyte composite paste A solid electrolyte composite paste was produced in the same manner as in Examples 4-1 to 4-3 using the solid electrolyte fusion powder and solid electrolyte powder described above.

(d) Preparation of positive electrode composite material layer A positive electrode composite material layer (positive electrode composite material sheet) was produced in the same manner as in Examples 4-1 to 4-3.

(e) Formation of solid electrolyte composite layer A solid electrolyte composite precursor layer is formed on the positive electrode composite layer using the solid electrolyte composite paste in the same manner as in Examples 4-1 to 4-3. did.

Next, the solid electrolyte precursor layer was irradiated with laser light using a Yb fiber laser with a wavelength of 1080 nm under the conditions listed in Table 8. As a result, the solid electrolyte fusion powder was not melted by laser irradiation, and the solid electrolyte composite materials and the positive electrode composite material layer and the solid electrolyte composite material layer were not fused and bonded.

INDUSTRIAL APPLICATION This invention is suitable for the manufacture of the secondary battery used, for example as the main power supply of a mobile communication device, a portable electronic device, an electric bicycle, an electric two-wheeled vehicle, an electric vehicle, etc.

Claims (8)

A method for manufacturing a secondary battery, comprising irradiating a powder material containing a laser light absorbing component with laser light to sinter the powder material to form an electrode layer, the method comprising:
The laser light absorption component is at least one selected from the group consisting of CrO, FeO, MnO, CoO, and NiO,
The powder material is a positive electrode active material powder containing 15 to 55% of Na ₂ O, 20 to 70% of CrO+FeO+MnO+CoO+NiO, and 15 to 60 % of P ₂ O ₅ +SiO ₂ +B ₂ O ₃ in terms of mol% in oxide terms. , a method for manufacturing a secondary battery. A method for manufacturing a secondary battery, comprising irradiating a powder material containing a laser light absorbing component with laser light to sinter the powder material to form an electrode layer, the method comprising:
_The laser light absorption component is _TiO2 , _{V2O5 , Cr2O3} , _{MnO, FeO, CoO, NiO, CuO, Er2O3 , Nd2O3 , Sm2O3 ,} and _{Dy2O3 .} At least one species selected from the group consisting of;
The powder material has a mole percentage of B i ₂ O ₃ 25 to 70 %, Nb ₂ O ₅ 0 to 49 %, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd ₂ O ₃ in terms of mol% in terms of oxides. A method for producing a secondary battery, which is a negative electrode active material powder containing +Sm ₂ O ₃ +Dy ₂ O ₃ 0.3 to 50 %, SiO ₂ 20 to 50 %, and Na ₂ O 5 to 20 %. A method for manufacturing a secondary battery, comprising: irradiating a powder material containing a laser light absorbing component with laser light to sinter the powder material to form a solid electrolyte layer, the method comprising:
_The laser light absorption component is _TiO2 , _{V2O5 , Cr2O3} , _{MnO, FeO, CoO, NiO, CuO, Er2O3 , Nd2O3 , Sm2O3 ,} and _{Dy2O3 .} At least one species selected from the group consisting of;
The powder material contains Na ₂ O 1 to 32.7 %, SiO ₂ +B ₂ O ₃ +P ₂ O ₅ 50 to 80%, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO + FeO + CoO + NiO + CuO + Er ₂ in terms of mol% in terms of oxides. A method for producing _a secondary battery, which is a solid electrolyte powder containing 0.3 to 30 % _{of O 3 +} Nd 2 O ₃ +Sm ₂ O ₃ +Dy 2 O 3. The method for manufacturing a secondary battery according to any one of claims 1 to 3, wherein the wavelength of the laser light is 750 to 1600 nm. 5. The method for manufacturing a secondary battery according to claim 1, wherein the laser beam is a semiconductor laser, a YAG laser, a Yb fiber laser, or a YVO ₄ laser. A powder material containing a laser light absorbing component and used to form an electrode layer of a secondary battery by irradiating and sintering with laser light,
The laser light absorption component is at least one selected from the group consisting of CrO, FeO, MnO, CoO, and NiO,
The powder material is a positive electrode active material powder containing 15 to 55% of Na ₂ O, 20 to 70% of CrO+FeO+MnO+CoO+NiO, and 15 to 60 % of P ₂ O ₅ +SiO ₂ +B ₂ O ₃ in terms of mol% in oxide terms. , powder material. A powder material containing a laser light absorbing component and used to form an electrode layer of a secondary battery by irradiating and sintering with laser light,
_The laser light absorption component is _TiO2 , _{V2O5 , Cr2O3} , _{MnO, FeO, CoO, NiO, CuO, Er2O3 , Nd2O3 , Sm2O3 ,} and _{Dy2O3 .} At least one species selected from the group consisting of;
The powder material has a mole percentage of B i ₂ O ₃ 25 to 70 %, Nb ₂ O ₅ 0 to 49 %, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO+FeO+CoO+NiO+CuO+Er ₂ O ₃ +Nd ₂ O ₃ in terms of mol% in terms of oxides. A powder material that is a negative electrode active material powder containing +Sm ₂ O ₃ +Dy ₂ O ₃ 0.3 to 50 %, SiO ₂ 20 to 50 %, and Na ₂ O 5 to 20 %. A powder material containing a laser light absorbing component, which is used to form a solid electrolyte layer of a secondary battery by irradiating and sintering with laser light,
_The laser light absorption component is _TiO2 , _{V2O5 , Cr2O3} , _{MnO, FeO, CoO, NiO, CuO, Er2O3 , Nd2O3 , Sm2O3 ,} and _{Dy2O3 .} At least one species selected from the group consisting of;
The powder material contains Na ₂ O 1 to 32.7 %, SiO ₂ +B ₂ O ₃ +P ₂ O ₅ 50 to 80%, TiO ₂ +V ₂ O ₅ +Cr ₂ O ₃ +MnO + FeO + CoO + NiO + CuO + Er ₂ in terms of mol% in terms of oxides. A powder material which is _a solid electrolyte powder containing 0.3 to 30 % of O ₃ +Nd ₂ O ₃ +Sm ₂ O ₃ +Dy ₂ O 3 .