JP2014035818A - All-solid-state lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an all-solid-state high capacity lithium ion secondary battery having excellent output characteristics, by preventing short circuit between positive and negative electrodes.SOLUTION: In an all-solid-state high capacity lithium ion secondary battery, a positive electrode layer and a negative electrode layer are laminated while sandwiching a solid electrolyte layer. At least any one of the positive electrode layer and negative electrode layer is an electrode mixture layer containing active material particles and ion conductive assistant particles. When the surface roughness Rmax formed by the active material particles on the surface of the electrode mixture layer on the solid electrolyte layer side is prescribed, average particle size of solid electrolyte particles forming the solid electrolyte layer is 0.1-1.0 times of the Rmax, and the thickness of the solid electrolyte layer is 5 times or more of the Rmax, and less than 100 times of the average particle size of the solid electrolyte particles forming the solid electrolyte layer.

Description

  The present invention relates to an all solid lithium ion secondary battery.

  Lithium ion secondary batteries are widely used in portable devices because of their large capacity per unit volume and weight, and in the future, research and development for higher capacity applications such as electric vehicles are being actively promoted.

  A lithium ion secondary battery mainly includes a positive electrode, a negative electrode, and a liquid electrolyte layer disposed between the positive electrode and the negative electrode. Conventionally, the positive electrode and / or the negative electrode are formed by using an electrode-forming coating solution (for example, slurry or paste) containing each electrode active material, a binder, and a conductive additive. Has been.

  Since the liquid electrolyte uses a flammable organic solvent, a structural measure for preventing liquid leakage is required. The need for this measure increases as the battery size and capacity increase.

  All-solid-state lithium ion secondary batteries that use a solid electrolyte as the electrolyte layer do not use flammable organic solvents, so there is a possibility of drastically solving the battery leakage of conventional batteries. Is underway.

  On the other hand, in order to improve battery capacity, development of materials having a potential of 5 V or more with respect to lithium metal has been advanced in recent years. However, since the potential window of the liquid electrolyte is narrow, there is a problem that the electrolyte is decomposed when the battery is operated. On the other hand, when a solid electrolyte is used, there is an advantage that a high-capacity battery can be obtained by having a wide potential window and suppressing decomposition of the electrolyte.

  Solid electrolytes include ionic conductive polymers such as polyethylene oxide as organic materials, and oxide-based solid electrolytes and sulfide-based solid electrolytes as inorganic materials. However, these solid electrolytes have a problem that output characteristics are inferior because lithium ion conductivity is low as compared with liquid electrolytes. As one of the means for solving such problems, it has been reported that the ionic conductivity of the sulfide-based solid electrolyte is equivalent to that of the liquid electrolyte, and the realization of a high-power all-solid lithium ion secondary battery has been made. Expectations are rising. (For example, Non-Patent Document 1)

JP 2005-327528 A JP-A-1996-195219 JP2011-65982A JP 2009-93947 A

Nature Materials, published online, 31 July 2011

  However, the output characteristics of the all-solid-state lithium ion secondary battery are still not sufficient as compared with the conventional battery using a liquid electrolyte. This is because the distance between the positive and negative electrodes of a conventional battery using a liquid electrolyte is set to about several tens of μm defined by the thickness of the separator, whereas the distance between the positive and negative electrodes of an all-solid lithium ion secondary battery. This is because 10 times or more is required for the following reasons.

  In a conventional battery using a liquid electrolyte, since the liquid electrolyte can easily contact the active material particles in the electrode, good lithium ion conduction between the electrolyte and the active material particles can be ensured. On the other hand, in an all-solid lithium ion secondary battery using a solid electrolyte, in order to ensure lithium ion conduction in the electrode mixture, in the positive electrode mixture, the active material particles include solid electrolyte particles that are ion conductive assistants and In some cases, electronically conductive auxiliary particles such as carbon black are dispersed and used. Then, a positive electrode composite material layer (electrode composite material layer) is formed by, for example, pressure molding the composite material, and a solid electrolyte layer made of only solid electrolyte powder is provided thereon. Further, a negative electrode mixture layer or a negative electrode layer made of Li, Li—In alloy or the like is disposed on the solid electrolyte layer.

Active material particles such as LiCoO ₂ and LiNiO ₂ contained in the electrode mixture are usually particles having a particle diameter of several μm to several tens of μm (for example, Patent Documents 1, 2, and 3). This is because when the particle size is reduced, the surface area increases, the resistance of the grain boundary increases, and both the output and capacity of the battery tend to decrease. To obtain a battery with high capacity and high output, lithium ion conduction is required. It is preferable to use particles with few grain boundaries that hinder the prevention.

  However, such an electrode mixture layer is a green compact obtained by pressure-molding particles, and a large number of active material particles necessarily exist on the surface of the electrode mixture layer. In order to prevent the active material particles from passing between the positive and negative electrodes and causing a short circuit, it is necessary to make the solid electrolyte layer thicker than at least the maximum particle diameter of the active material particles. Considering the expansion and contraction of the active material particles due to the charge / discharge cycle, the layer thickness is several times or more that of the particles. This is considered to be one of the causes that the output as the all-solid-state lithium ion secondary battery is inferior to that of the conventional battery using the liquid electrolyte even if the lithium ion conductivity of the solid electrolyte is equivalent to that of the liquid electrolyte.

  The present invention has been made in view of the above-described problems of the prior art, and it is possible to obtain an all-solid lithium ion secondary battery that prevents short-circuit between positive and negative electrodes, and has high capacity and high output characteristics. Objective.

  In order to achieve the above object, an all-solid-state lithium ion secondary battery according to the present invention comprises a positive electrode layer and a negative electrode layer laminated with a solid electrolyte layer interposed therebetween, and at least one of the positive electrode layer and the negative electrode layer. Is an electrode mixture layer including active material particles and ion conductive auxiliary particles, and the surface roughness Rmax formed by the active material particles on the surface of the electrode mixture layer on the solid electrolyte layer side is defined. The average particle diameter of the solid electrolyte particles forming the solid electrolyte layer is 0.1 times or more and less than 1.0 times Rmax, and the thickness of the solid electrolyte layer is 5 times or more of Rmax. It is less than 100 times the average particle diameter of the solid electrolyte particles forming the layer.

  By doing so, the contact resistance between the electrode mixture layer and the solid electrolyte layer can be reduced, and the interface resistance between the solid electrolyte particles of the solid electrolyte layer can be prevented from becoming the rate-limiting factor for lithium ion conduction. It is possible to obtain an all-solid-state lithium ion secondary battery that has high capacity and high output characteristics. Moreover, the short circuit between positive and negative electrodes can be prevented reliably.

  Furthermore, the all solid lithium ion secondary battery according to the present invention preferably contains a sulfide solid electrolyte as the ion conductive auxiliary particles.

  Thereby, the contact resistance between the active material particles in the electrode mixture layer and the ion conductive auxiliary particles can be lowered, and a high-power all-solid lithium ion secondary battery can be obtained.

  Furthermore, in the all-solid-state lithium ion secondary battery according to the present invention, Rmax formed by the active material particles in the electrode mixture layer is preferably less than 1.0 μm.

  As a result, the solid electrolyte layer can be thinned without causing a short circuit between the positive and negative electrodes, and a high-power all-solid lithium ion secondary battery can be obtained.

  Furthermore, the all-solid-state lithium ion secondary battery according to the present invention preferably includes a solid electrolyte layer having a thickness of 50 times or less the average particle diameter of the solid electrolyte particles contained in the solid electrolyte layer.

  Thereby, the intergranular resistance between the solid electrolyte particles contained in the solid electrolyte layer is lowered, and a high-power all-solid lithium ion secondary battery is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the short circuit between positive / negative electrodes can be prevented, and the all-solid-state lithium ion secondary battery excellent in the output characteristic of high capacity | capacitance and high output can be obtained.

It is sectional drawing of the all-solid-state lithium ion secondary battery in one Embodiment of this invention. It is sectional drawing which shows the calculation method of Rmax which an active material particle forms in the electrode compound-material layer surface in one Embodiment of this invention.

  FIG. 1 is a schematic cross-sectional view of an all solid lithium ion secondary battery which is a preferred embodiment of the present invention. As an example, the all-solid-state lithium ion secondary battery includes a positive electrode active material particle 21 and an ion conductive auxiliary agent particle 20 on a positive electrode current collector 11 and a positive electrode mixture layer 20 on which solid electrolyte particles are formed. The solid electrolyte layer 30 containing 31 is arrange | positioned, and the negative electrode layer 40 and the negative electrode collector 12 are laminated | stacked further on it.

  In the all solid lithium ion secondary battery in the present embodiment, the electrolyte is composed of a substantially solid component.

(Electrode mixture layer)
The positive electrode active material layer 20, which is a positive electrode active material layer that is an example of the electrode composite material layer according to the present embodiment, includes positive electrode active material particles 21 that are active material particles according to the present embodiment and ion conductive auxiliary particles. 22 is included. Examples of the positive electrode active material particles 21 include transition metal oxides such as LiCoO ₂ , LiNiO ₂ , LiNi _1-x Co _x O ₂ , LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , and LiMn ₂ O ₄ , Materials having an olivine structure represented by the formula LiMPO ₄ (wherein M is Fe, Mn, Co, Ni, V, VO, Cu, etc.), transition metal sulfides such as TiS ₂ , MoS _2, FeS ₂ , vanadium Oxides, organic sulfur compounds, and the like can be used.

In the case of the negative electrode active material layer, the negative electrode active material particles that are the active material particles of the present embodiment include carbon materials such as graphite, carbon black, carbon fiber, and carbon nanotube, Si, SiO, Sn, SnO, and CuSn. An alloy material such as LiIn, an oxide such as Li ₄ Ti ₅ O ₁₂ , Li metal, or the like can be used.

The ion conductive auxiliary particles 22 are preferably inorganic materials exemplified below having lithium ion conductivity.
(1) Li ₂ S—P ₂ S ₅ series, Li ₂ S—SiS ₂ —LiPO ₃ series, Li ₂ S—SiS ₂ —LiI series sulfide glass and glass ceramics containing Li and S,
(2) Thioricicon type crystals such as Li _4-x Ge _1-x P _x S ₄ , Li _4-x Si _1-x P _x S ₄ , Li ₁₀ GeP ₂ S ₁₂ ,
(3) NASICON type crystals such as Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ ,
(4) Perovskite crystals such as Li _0.35 La _0.55 TiO ₃ , LiSr ₂ TiTaO ₆ ,
(5) Garnet-type crystals such as Li ₇ La ₃ Zr ₂ O ₁₂ ,
(6) a silicon type crystal such as Li ₁₄ ZnGe ₄ O ₄ ;
(7) Oxide crystals such as LiNbO3 and LiTaO3 and glass,
(8) Li-doped β-Al ₂ O ₃ crystal,
(9) Oxide glass such as Li ₂ O—SiO ₂ —B ₂ O ₃ system, Li ₂ O—SiO ₂ —ZrO ₂ , Li ₂ O—SiO ₂ —V ₂ O ₅ system,
(10) LiPON glass (Li-P-N-O glass),
(11) LiI crystal,
(12) Li ₃ PO ₄ crystal and glass.

  Of these, sulfide solid electrolytes such as sulfide glass and glass ceramics, or thiolysicon type crystals are preferable because they have high ionic conductivity. Sulfide solid electrolytes are advantageous in that they do not require sintering because they have lower grain boundary resistance than oxide solid electrolytes. Therefore, a sulfide solid electrolyte is more preferable because high ionic conductivity can be obtained even with a green compact, and a high-power all-solid lithium ion secondary battery can be easily obtained.

  For the production of these sulfide glasses, a mechanical milling method and a melt quenching method may be used, and among them, a simple mechanical milling method is preferable. According to the mechanical milling method, glass can be produced at room temperature, and the apparatus can be simplified and the process cost can be reduced. Glass ceramics are obtained by heat-treating sulfide glass and tend to have higher ionic conductivity than glass. The heat treatment temperature is preferably performed at a temperature between 200 ° C. and 400 ° C., for example. For producing a sulfide crystal such as a thiolysicon type crystal, for example, a solid phase reaction method is preferably used, and the reaction temperature is preferably about 400 ° C. to 700 ° C.

  The ratio between the active material particles and the ion conductive auxiliary particles 22 is not particularly limited, but the capacity per battery volume can be increased by increasing the active material particle ratio as much as possible within the range in which the ion conductive path can be constructed. Therefore, it is preferable. Specifically, the weight ratio between the active material particles and the ion conductive auxiliary particles is preferably 95: 5 to 20:80. If the weight ratio of the active material particles exceeds this range, the ionic conductive path due to the ion conductive auxiliary particles becomes difficult to form, so the output of the battery tends to be low, and the weight ratio of the active material particles is below this range. And battery capacity tends to be low.

  The particle diameter of the ion conductive auxiliary particles 22 is desirably smaller than the maximum particle diameter of the active material particles. By doing so, the active material particles and the ion conductive auxiliary particles 22 are in close contact with each other in the electrode mixture layer, and an ion conductive path is reliably formed, and the output of the battery can be increased. The maximum particle diameter of the ion conductive auxiliary particles 22 in the present embodiment is obtained from an observation image obtained by observing an arbitrary region with a scanning electron microscope at a magnification at which about 100 to 500 particles are observed in the field of view. The maximum particle diameter of the ferret diameter (constant direction diameter). The specific measurement magnification is about 5000 to 20000 times.

The electrode mixture layer is formed, for example, by compression molding an electrode mixture containing active material particles and ion conductive auxiliary particles 22. In addition to compression molding, a component such as a binder or a solvent may be added to form a paste, and the electrode mixture layer may be formed by applying and drying this paste. The solvent is not only removed by drying, but a solution obtained by dissolving a Li salt such as LiPF _{6 in} a carbonate-based solvent or an ionic liquid may be left in the electrode mixture layer or the solid electrolyte layer 30.

  The electrode mixture layer including the active material particles and the ion conductive auxiliary particles 22 has a certain surface roughness depending on the particle diameter, shape, degree of dispersion, compressibility, and the like of the particles. In the present embodiment, Rmax formed by the active material particles on the surface of the electrode mixture layer is a solid electrolyte layer 30 in a cross section where an arbitrary length of 0.1 mm or more between the electrode mixture layer and the solid electrolyte layer interface can be observed. The maximum roughness of the surface formed only by the active material particles at the boundary portion between the electrode material layer and the electrode mixture layer (the surface of the electrode mixture layer on the solid electrolyte layer 30 side).

  Cross-sectional observation can be performed using a scanning electron microscope at a magnification of about 5000 to 20000 times. FIG. 2 shows an example of the enlarged view of FIG. 1. The positive electrode mixture layer 20 that is an electrode mixture layer has an interface with the solid electrolyte layer 30, and the positive electrode mixture layer 20 that is an electrode mixture layer. The uneven surface is indicated by a boundary line a so that the surface of the positive electrode active material particles 21 which are the active material particles therein can be drawn and the roughness of the active material particles at the interface can be measured. The reference line A1 substantially parallel to the positive electrode current collector 11 is provided on the positive electrode current collector 11 side of the boundary line a so as to be in contact with the most concave portion, and the distance from the line A2 in contact with the most convex portion parallel to this is measured. Let the distance be Rmax.

  The degree of roughness of the boundary line a affects the short circuit between the positive and negative electrodes of the all-solid lithium ion secondary battery. For this reason, it has been found that controlling Rmax, which is the maximum value of roughness, can reliably prevent a short circuit. In addition, controlling Rmax may include, for example, a large number of roughness portions where Ra (arithmetic mean roughness) is equal to or higher than Ra, and short-circuiting between the positive and negative electrodes of the battery can be reliably prevented only by controlling Ra. Therefore, a certain effect cannot be obtained.

  Rmax formed by the active material particles on the surface of the positive electrode mixture layer 20 which is an electrode mixture layer is preferably less than 1.0 μm. By doing so, the solid electrolyte layer 30 can be thinned without causing a short circuit between the positive and negative electrodes of the battery, and an all solid lithium ion secondary battery showing high output can be obtained.

  In order to reduce Rmax formed by the active material particles on the surface of the electrode mixture layer, it is preferable to make the surface roughness of the mold as small as possible when molding using a mold. For this purpose, it is desirable to increase the compression pressure of the electrode mixture layer at the time of molding to such an extent that the molded body does not break. Specifically, it is preferable to set the pressure to 1 MPa or more and less than 100 MPa. In this way, the density of the electrode mixture layer is improved, the charge / discharge capacity per volume is improved, and the contact between the active material particles and the ion conductive auxiliary particles 22 becomes dense, so that the battery The effect of improving the output is obtained.

  In order to make Rmax formed by the active material particles on the surface of the electrode mixture layer less than 1.0 μm, it is preferable to reduce the maximum particle diameter of the active material particles on the surface of the electrode mixture layer to less than about 1.0 μm. . The maximum particle diameter of the active material particles in the electrode mixture layer in this embodiment is observed at a magnification at which about 100 to 500 particles can be observed in the field of view with a scanning electron microscope. The maximum particle diameter in the direction direction). The specific measurement magnification is about 5000 to 20000 times.

Active material particles having high electronic conductivity such as LiCoO ₂ and LiNiO ₂ are preferably particles having few grain boundaries in order to obtain a high battery capacity and output, and usually have a particle size of about 1.0 μm to 10 μm. It is preferable to use particles. In order to make Rmax formed by the active material particles of the electrode mixture layer using these active materials less than 1.0 μm, particles having a maximum particle diameter of less than 1.0 μm are mixed to form the electrode mixture layer. It is preferable.

Further, a first electrode mixture layer is formed using particles having a maximum particle diameter of several μm or more, and a second electrode mixture layer containing particles having a maximum particle diameter of less than 1.0 μm is formed on the surface thereof. You may do it. In this way, an active material using particles having a particle diameter of several μm to several tens of μm, such as LiCoO ₂ or LiNiO ₂ , usually forms active material particles even in the electrode mixture layer. Rmax to be set can be less than 1.0 μm.

A material having an olivine structure represented by a general formula LiMPO ₄ (wherein M is Fe, Mn, Co, Ni, V, VO, Cu, etc.) is a highly heat-resistant active material having a particle diameter of 100 nm or less. A hybridized material obtained by coating the surface of the active material particles with a conductive auxiliary agent can be used. In the present embodiment, it is preferable to use an active material having such a hybridized olivine structure with a particle diameter of 100 nm or less, and the Rmax formed by the active material particles on the surface of the electrode mixture layer is more easily set to 1. It can be less than 0 μm.

  The active material particles having a particle size of 100 nm or less can be obtained by a normal solid phase firing method, a method using an excess lithium source (lithium excess method), a liquid phase laser ablation method, a spray pyrolysis method, a sol-gel. Method, microwave heating method, hydrothermal synthesis method and the like can be used. The obtained particles may be pulverized and pulverized by various known means such as a ball mill.

  In order to reduce the Rmax formed by the active material particles in the electrode mixture layer, the active material particles having sharp protrusions or those having a particle surface with a small concavo-convex shape closer to a sphere than the active material particles having a large aspect ratio Are preferably used. In order to make the particle surface smooth and spherical, for example, as disclosed in Patent Document 4, a method of mechanically rubbing particles in an apparatus, a method of rubbing particles in an air stream, or the like is appropriately used. be able to.

  After forming the electrode mixture layer, Rmax formed by the active material particles can be lowered by treating the surface of the electrode mixture layer. For example, a sand blast method, a reverse sputtering method in plasma, an ion milling method using an ion beam, or the like can be used.

The surface of the active material particles may be coated to reduce the interfacial resistance with the solid electrolyte. Coating materials include LiNbO ₃ , LiTaO ₃ , Li ₄ Ti ₅ O ₁₂ , Li _x La _{(2-x) / 3} TiO ₃ (0.1 ≦ x ≦ 0.5), Li _{7 + x} La ₃ Zr ₂ O _{12+ (X / 2)} (−5 ≦ x ≦ 3), Li _3.6 Si _0.6 P _0.4 O ₄ , Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li _{1. 8 Cr 0.8 Ti 1.2 (PO 4} ) 3, Li 1.4 In 0.4 Ti 1.6 (PO 4) 3 , etc. can be used. The thickness of the coating is preferably 1 nm to 10 nm.

  The electrode mixture layer may contain a conductive additive in order to impart electronic conductivity. As the conductive auxiliary agent, carbon materials such as carbon black such as acetylene black and ketjen black and carbon fiber are preferably used.

(Solid electrolyte layer)
A solid electrolyte layer 30 is provided on the surface of the electrode mixture layer. The solid electrolyte layer 30 may be an integrated member such as a sintered body, or may be a green compact of the solid electrolyte particles 31. The solid electrolyte layer 30 may include insulating inorganic particles such as alumina and silica as necessary. The solid electrolyte particles 31 used for the solid electrolyte layer 30 may be made of a material different from that of the ion conductive auxiliary particles 22. However, since the same material as that used for the ion conductive auxiliary particles 22 tends to reduce the interface resistance, it is more preferably used. In particular, in the case of a sulfide solid electrolyte, a high ion conductivity can be obtained even with a green compact, so that a good ion path between the electrode mixture layer and the solid electrolyte layer 30 can be easily formed, and the output of the all-solid lithium ion secondary battery Can be increased.

As the solid electrolyte particles 31, it is preferable to use the same inorganic materials exemplified below as those of the ion conductive auxiliary particles 22.
(1) Li ₂ S—P ₂ S ₅ series, Li ₂ S—SiS ₂ —LiPO ₃ series, Li ₂ S—SiS ₂ —LiI series sulfide glass and glass ceramics containing Li and S,
(2) Thioricicon type crystals such as Li _4-x Ge _1-x P _x S ₄ , Li _4-x Si _1-x P _x S ₄ , Li ₁₀ GeP ₂ S ₁₂ ,
(3) NASICON type crystals such as Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ ,
(4) Perovskite crystals such as Li _0.35 La _0.55 TiO ₃ , LiSr ₂ TiTaO ₆ ,
(5) Garnet-type crystals such as Li ₇ La ₃ Zr ₂ O ₁₂ ,
(6) a silicon type crystal such as Li ₁₄ ZnGe ₄ O ₄ ;
(7) Oxide crystals such as LiNbO3 and LiTaO3 and glass,
(8) Li-doped β-Al ₂ O ₃ crystal,
(9) Oxide glass such as Li ₂ O—SiO ₂ —B ₂ O ₃ system, Li ₂ O—SiO ₂ —ZrO ₂ , Li ₂ O—SiO ₂ —V ₂ O ₅ system,
(10) LiPON glass (Li-P-N-O glass),
(11) LiI crystal,
(12) Li ₃ PO ₄ crystal and glass.

  In this embodiment, the average particle diameter of the solid electrolyte particles 31 in the solid electrolyte layer 30 is 0.1 times or more and less than 1.0 times Rmax formed by the active material particles on the surface of the electrode mixture layer. By doing in this way, the active material particle of the electrode compound-material layer surface and the solid electrolyte particle 31 can contact effectively, an ion conductive path can be constructed | assembled, and battery capacity and output can be improved. If it is 1.0 times or more, the contact area between the solid electrolyte particles 31 and the active material particles on the surface of the electrode mixture layer is insufficient, so that the output of the battery is lowered. If it is less than 0.1 times, the interface resistance between the solid electrolyte particles is low. The output of the battery decreases due to the tendency to suppress the diffusion of lithium ions because it cannot be ignored. The average particle diameter in the present embodiment is the number average particle diameter of the ferret diameter (constant direction diameter) obtained from an image measured with a scanning electron microscope at a magnification at which about 100 to 500 particles are observed in the field of view. . The specific measurement magnification is about 5000 to 20000 times.

  Moreover, the thickness of the solid electrolyte layer 30 in this embodiment is 5 times or more of Rmax formed by the active material particles on the surface of the electrode mixture layer. By doing in this way, the all-solid-state lithium ion secondary battery by which the short circuit between positive and negative electrodes was prevented reliably can be obtained. If it is less than 5 times, the capacity and output may be temporarily improved. However, repeating charging and discharging may cause a short circuit between the positive and negative electrodes, and may not function as a battery.

  Furthermore, the thickness of the solid electrolyte layer 30 in the present embodiment is less than 100 times the average particle diameter of the solid electrolyte particles 31 in the solid electrolyte layer 30. By doing in this way, it becomes possible to prevent the lithium ion electroconductivity fall by the interface resistance between the solid electrolyte particles in the solid electrolyte layer 30, and a higher output all-solid-state lithium ion secondary battery can be obtained. .

  The thickness of the solid electrolyte layer 30 is preferably 10 times or more the average particle diameter of the solid electrolyte particles 31. If it is less than 10 times, it tends to be difficult to be integrated as the solid electrolyte layer 30, and when the molded body is extracted from the mold after compression molding, the strength tends to decrease and cracks and chips are likely to occur.

(Battery cell)
As an example, the all solid lithium ion secondary battery is formed by compressing and molding an electrode mixture containing positive electrode active material particles 21 and ion conductive auxiliary particles 22 on a positive electrode current collector 11 using a mold or the like. The electrode composite material layer 20 is formed. The solid electrolyte layer 30 is formed by compression-molding the solid electrolyte particles 31 on the surface of the positive electrode mixture layer 20 opposite to the positive electrode current collector 11. You may use the pellet which compression-molded the solid electrolyte particle 31 previously. In addition to compression molding, a component such as a binder or a solvent may be added to obtain a paste, and the electrode mixture layer or the solid electrolyte layer 30 may be formed by applying and drying the paste. The solvent here is not only removed by drying, but a carbonate salt solvent in which a Li salt such as LiPF ₆ is dissolved, or an ionic liquid may be left in the electrode mixture layer or the solid electrolyte layer 30.

  On the surface of the solid electrolyte layer 30 opposite to the positive electrode mixture layer 20, a negative electrode layer 40 made of a metal foil such as Li or a Li—In alloy, or a negative electrode composite containing active material particles and solid electrolyte particles 31. A negative electrode mixture layer obtained by compression-molding the material is provided. The negative electrode current collector 12 is provided on the surface of the negative electrode layer 40 or the negative electrode mixture layer opposite to the solid electrolyte layer 30.

  The current collector is not particularly limited as long as it is an electronic conductor that can be used in a configured battery.

  The positive electrode current collector 11 may be made of aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, or the like, for the purpose of improving adhesiveness, conductivity, and oxidation resistance. A material obtained by treating the surface such as carbon, nickel, titanium, silver, or the like can be used. Negative electrode current collector materials include copper, stainless steel, nickel, aluminum, titanium, baked carbon, conductive polymer, conductive glass, Al-Cd alloy, etc., as well as improved adhesion, conductivity, and oxidation resistance For this purpose, a material obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver or the like can be used. The surface of these materials can be oxidized. As for these shapes, in addition to the foil shape, a film shape, a sheet shape, a net shape, a punched shape, an expanded shape, a lath body, a porous body, a foamed body, a formed body of a fiber group, and the like can be used.

  The present invention has been described based on the embodiments. It will be understood by those skilled in the art that the embodiments are illustrative, and that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. By the way. Accordingly, the description and drawings herein are to be regarded as illustrative rather than restrictive.

Example 1
(Electrode mixture layer for positive electrode)
LiCoO ₂ (maximum particle diameter 2.00 μm) was used as the positive electrode active material particles. An oxide solid electrolyte Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ having an average particle diameter of 1.00 μm was used as an ion conductive auxiliary, and the composition ratio of the electrode mixture for positive electrode was determined according to the positive electrode active material. 80 wt% of particles, 10 wt% of ionic conductive auxiliary particles, 10 wt% of conductive auxiliary (acetylene black, Denka Black DAB50 manufactured by Denki Kagaku Kogyo Co., Ltd.), and the weighed mixed particles are mixed and dispersed in a mortar. The mixed particles were compressed at 20 MPa to obtain a positive electrode mixture layer.

(Solid electrolyte layer)
Li ₂ S particles (high purity chemical research laboratory, model number LII06PB) and P ₂ S ₅ particles (Aldrich company, model number 232106) with a molar ratio of 75:25 were put into a planetary ball mill (Fritch company), and pulverized at 350 rpm for 6 hours. Mixed. The obtained particles were heat treated at 250 ° C. for 2 hours to form glass ceramics. This was again pulverized with a planetary ball mill at 350 rpm for 1 hour to obtain sulfide solid electrolyte particles having an average particle size of 0.70 μm. The solid electrolyte particles were put on the surface of the positive electrode mixture layer in the tablet molding machine and compressed by the tablet molding machine to obtain a laminate in which the positive electrode mixture layer and the solid electrolyte layer were integrated. Table 1 shows a list of these materials and blending ratios.

(Create battery cells)
The laminated body is taken out, Li foil (High Purity Chemical Laboratory, thickness 0.25 μm) is pasted on the surface of the solid electrolyte layer opposite to the positive electrode mixture layer, and the obtained laminated body is about 1 MPa. The battery cell was attached to a jig that was pressurized with pressure. Six battery cells having the same configuration were prepared.

(Battery cell evaluation)
About 5 of the 6 batteries created, charge / discharge was performed under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.0 V / 3.0 V (end of charge voltage / end of discharge voltage). And an average discharge capacity of 84 mAh / g (67% of effective capacity) was obtained. Under the 3C condition, an average discharge capacity of 57 mAh / g was obtained, and a 68% discharge capacity under the 0.1C condition was obtained. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit. The evaluation results are shown in Table 2.

(Evaluation of active material cross section)
For one battery that was not subjected to battery cell evaluation, cross-sectional observation (S-4700, manufactured by Hitachi, Ltd., acceleration voltage 5 kV) was performed using a scanning electron microscope. When the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined by the method shown in FIG. 2 of the embodiment, it was 1.70 μm, the thickness of the solid electrolyte layer was 45.0 μm, and the solid electrolyte of the solid electrolyte layer The average particle size of the particles was 0.70 μm. The average particle diameter of the solid electrolyte particles was 0.41 times Rmax, the thickness of the solid electrolyte was 26.5 times Rmax, and 64.3 times that of the solid electrolyte particles.

(Example 2)
The sulfide solid electrolyte particles used in the solid electrolyte layer of Example 1 were used as the ion conductive auxiliary particles, and the composition ratio of the electrode mixture layer for positive electrode was 75 wt% for positive electrode active material particles and 15 wt% for ion conductive auxiliary particles. As shown in Table 1, a battery cell was prepared in the same manner as in Example 1 except that the conductive assistant (acetylene black) was 10 wt%.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, the average discharge capacity was 89 mAh / g (71% of the effective capacity). there were. The average discharge capacity under the 3C condition was 64 mAh / g, which was 72% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 1.50 μm, the thickness of the solid electrolyte layer was 45.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.70 μm. The average particle diameter of the solid electrolyte particles was 0.47 times Rmax, the thickness of the solid electrolyte was 30.0 times Rmax, and 64.3 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 3)
LiCoO ₂ (maximum particle diameter 2.50 μm) was used as the positive electrode active material particles. The pulverization after the heat treatment of the sulfide solid electrolyte was performed at 500 rpm for 2 hours to obtain sulfide solid electrolyte particles having an average particle diameter of 0.20 μm. Using these particles as the ion conductive auxiliary particles of the positive electrode mixture layer and the solid electrolyte particles of the solid electrolyte layer, as shown in Table 1, the battery cell was formed with the same composition ratio of the electrode mixture layer as in Example 2. Created. The input amount of solid electrolyte particles in the solid electrolyte layer was 0.45 times that in Example 1.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, the average discharge capacity was 93 mAh / g (74% of the effective capacity). there were. The average discharge capacity under the 3C condition was 70 mAh / g, which was 75% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 2.00 μm, the thickness of the solid electrolyte layer was 20.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.20 μm. The average particle diameter of the solid electrolyte particles was 0.10 times Rmax, the thickness of the solid electrolyte was 10.0 times Rmax, and 100.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

Example 4
The same material as in Example 3 was used except that LiCoO ₂ (maximum particle diameter 0.50 μm) was used as the positive electrode active material particles, and the amount of solid electrolyte particles charged in the solid electrolyte layer was 0.30 times that in Example 1. As shown in Table 1, battery cells were prepared.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, the average discharge capacity was 95 mAh / g (76% of the effective capacity). there were. The average discharge capacity under the 3C condition was 73 mAh / g, 77% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 14.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.20 μm. The average particle diameter of the solid electrolyte particles was 0.25 times Rmax, the thickness of the solid electrolyte was 17.5 times Rmax, and 70.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 5)
The same material as in Example 4 was used except that sulfide solid electrolyte particles having an average particle diameter of 0.70 μm were used for the solid electrolyte layer, and the amount of solid electrolyte particles in the solid electrolyte layer was 0.15 times that in Example 1. As shown in Table 1, battery cells were prepared.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, the average discharge capacity was 103 mAh / g (82% of the effective capacity). there were. The average discharge capacity under the 3C condition was 87 mAh / g, which was 84% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 7.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.70 μm. The average particle diameter of the solid electrolyte particles was 0.88 times Rmax, the thickness of the solid electrolyte was 8.8 times Rmax, and 10.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 6)
As shown in Table 1, a green compact in which the electrode mixture layer for positive electrode and the solid electrolyte layer were integrated with the same material and mixing ratio as in Example 5 was prepared. Si (Aldrich) with a maximum particle size of 0.10 μm was used as the negative electrode active material, 55 wt% of the negative electrode active material particles, 25 wt% of sulfide solid electrolyte particles with an average particle size of 0.20 μm as the ion conductive auxiliary particles, The mixed particles weighed 20 wt% of the agent (acetylene black) are mixed and dispersed in a mortar, and the mixture is put on the solid electrolyte layer and compression molded, and the positive electrode mixture layer, the solid electrolyte layer, and the negative electrode mixture layer Was obtained. The laminate was taken out and attached to a jig that was pressurized with a pressure of about 1 MPa to form a battery cell.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, the average discharge capacity was 100 mAh / g (80% of the effective capacity). there were. The average discharge capacity under the 3C condition was 82 mAh / g, which was 82% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not subjected to battery cell evaluation, the Rmax formed by the active material particles on the surface of the positive electrode mixture layer was determined to be 0.80 μm, and the thickness of the solid electrolyte layer was 7.0 μm. The average particle size of the solid electrolyte particles in the electrolyte layer was 0.70 μm. The average particle diameter of the solid electrolyte particles was 0.88 times Rmax, the thickness of the solid electrolyte was 8.8 times Rmax, and 10.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 7)
As shown in Table 1, the same material as in Example 4 was used, and the amount of solid electrolyte particles in the solid electrolyte layer was 0.20 times that in Example 1 to produce a battery cell.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 101 mAh / g (81% of the effective capacity) was Obtained. Under the 3C condition, an average discharge capacity of 84 mAh / g was obtained, and a discharge capacity of 83% of the 0.1C condition was obtained. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not subjected to battery cell evaluation, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 8.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.20 μm. The average particle size of the solid electrolyte particles was 0.25 times Rmax, the thickness of the solid electrolyte was 10.0 times Rmax, and 40.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 8)
LiPoO _{2 with} a maximum particle size of 30.0 μm as positive electrode active material particles, sulfide solid electrolyte particles with an average particle size of 0.70 μm as ionic conductive auxiliary particles, and positive electrode mixture mixed particles consisting of acetylene black as a conductive auxiliary agent A first positive electrode mixture layer was formed by pressure compression with a molding machine. On top of this, a positive electrode mixture comprising LiCoO _{2 having} a maximum particle size of 0.50 μm as a positive electrode active material, sulfide solid electrolyte particles having an average particle size of 0.20 μm as ion conductive auxiliary particles, and acetylene black as a conductive auxiliary agent The particles were put into a tablet molding machine and compressed to form a second positive electrode mixture layer, and a laminated positive electrode mixture layer composed of two layers having different maximum particle diameters was formed. As shown in Table 1, the composition ratio of each positive electrode mixture layer was set to 75 wt% positive electrode active material particles, 15 wt% ion conductive auxiliary particles, and 10 wt% conductive auxiliary agents. Thereafter, solid electrolyte particles having an average particle diameter of 0.70 μm were used, the input amount was 0.15 times that of Example 1, a solid electrolyte layer was formed, and a battery cell was produced.

  As a result of battery cell evaluation under conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 114 mAh / g (91% of the effective capacity) was Obtained. Under the 3C condition, an average discharge capacity of 99 mAh / g was obtained, and a discharge capacity of 87% of the 0.1C condition was obtained. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 7.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.70 μm. The average particle diameter of the solid electrolyte particles was 0.88 times Rmax, the thickness of the solid electrolyte was 8.8 times Rmax, and 10.0 times that of the solid electrolyte particles. The ratio of the thicknesses of the first positive electrode mixture layer and the second positive electrode mixture layer was 4: 1. The evaluation results are shown in Table 2.

Example 9
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 2. This positive electrode mixture layer is introduced into a sputtering chamber, evacuated to 10 ⁻⁴ Pa, Ar gas is introduced, and the surface of the positive electrode mixture layer is RFed at an output of 200 W under a pressure of 0.5 Pa. Sputtered.

  The positive electrode mixture layer is returned to the tablet molding machine, and a solid electrolyte layer is formed thereon using sulfide solid electrolyte particles having an average particle diameter of 0.20 μm with an input amount 0.20 times that of Example 1. A battery cell was created.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 110 mAh / g (88% of the effective capacity) was obtained. Obtained. Under the 3C condition, an average discharge capacity of 92 mAh / g was obtained, and a discharge capacity of 84% of the 0.1C condition was obtained. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.70 μm, the thickness of the solid electrolyte layer was 8.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.20 μm. The average particle diameter of the solid electrolyte particles was 0.29 times Rmax, the thickness of the solid electrolyte was 11.4 times Rmax, and 40.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 10)
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 2. This positive electrode mixture layer is introduced into a sputtering chamber, evacuated to 10 ⁻⁴ Pa, Ar gas is introduced, and LiCoO ₂ is RF-fed onto the mixture layer surface at an output of 200 W under a pressure of 0.5 Pa. Sputtered.

  The positive electrode mixture layer is returned to the tablet molding machine, and a solid electrolyte layer is formed thereon using sulfide solid electrolyte particles having an average particle diameter of 0.70 μm with an input amount 0.15 times that of Example 1. A battery cell was created.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 108 mAh / g (86% of the effective capacity) was Obtained. Under the 3C condition, an average discharge capacity of 90 mAh / g was obtained, and a discharge capacity of 83% of the 0.1C condition was obtained. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.90 μm, the thickness of the solid electrolyte layer was 7.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.70 μm. The average particle diameter of the solid electrolyte particles was 0.78 times Rmax, the thickness of the solid electrolyte was 7.8 times Rmax, and 10.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 11)
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 2. This positive electrode mixture layer was introduced into a sputtering chamber, and after evacuation to 10 ⁻⁴ Pa, Ar gas was introduced, and the mixture layer surface was RF-sputtered at an output of 200 W under a pressure of 0.5 Pa.

  The positive electrode mixture layer is returned to the tablet molding machine, and the solid electrolyte layer is formed thereon using sulfide solid electrolyte particles having an average particle diameter of 0.70 μm, with the input amount being 0.08 times that of Example 1. A battery cell was created.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 109 mAh / g (87% of the effective capacity) was Obtained. Under the 3C condition, an average discharge capacity of 93 mAh / g was obtained, and a discharge capacity of 85% of the 0.1C condition was obtained. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined in the same manner as in Example 1, and found to be 0.70 μm. The thickness of the solid electrolyte layer was 3 The average particle diameter of the solid electrolyte particles in the solid electrolyte layer was 0.70 μm. The average particle size of the solid electrolyte particles was 1.00 times Rmax, and the thickness of the solid electrolyte was 5.0 times Rmax and 5.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Example 12)
Except that LiFePO ₄ (maximum particle size 0.30 μm) was used as the positive electrode active material particles, the same material as in Example 4 was used as shown in Table 1, and the amount of sulfide solid electrolyte particles in the solid electrolyte layer was charged. A battery cell was prepared as 0.10 times of Example 1.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 140 mAh / g) and a charge / discharge end voltage of 4.0 V / 3.0 V, the average discharge capacity was 133 mAh / g (95% of the effective capacity). there were. The average discharge capacity under the 3C condition was 122 mAh / g, which was 92% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined in the same manner as in Example 1, and it was 0.50 μm. The thickness of the solid electrolyte layer was 5 The average particle diameter of the solid electrolyte particles of the solid electrolyte layer was 0.20 μm. The average particle diameter of the solid electrolyte particles was 0.40 times Rmax, the thickness of the solid electrolyte was 10.0 times Rmax, and 25.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Comparative Example 1)
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 4.

  The pulverization after the heat treatment of the sulfide solid electrolyte was performed at 600 rpm for 5 hours to obtain sulfide solid electrolyte particles having an average particle diameter of 0.06 μm. A battery cell was produced in the same manner as in Example 4 except that the sulfide solid electrolyte particles having an average particle size of 0.06 μm were used and the amount of the charged electrolyte was 0.10 times that of Example 1 to form a solid electrolyte layer.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 69 mAh / g (55% of the effective capacity) was Obtained. The average discharge capacity under the 3C condition was 33 mAh / g, which was 48% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not subjected to battery cell evaluation, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 5.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.06 μm. The average particle diameter of the solid electrolyte particles was 0.08 times Rmax, the thickness of the solid electrolyte was 6.3 times Rmax, and 83.3 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Comparative Example 2)
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 4. The pulverization of the sulfide solid electrolyte after the heat treatment was performed at 250 rpm for 30 minutes to obtain sulfide solid electrolyte particles having an average particle diameter of 1.00 μm. A battery cell was produced in the same manner as in Example 4 except that the sulfide solid electrolyte particles having an average particle size of 1.00 μm were used, and the solid electrolyte layer was formed with the input amount being 0.10 times that of Example 1.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 65 mAh / g (52% of the effective capacity) was Obtained. The average discharge capacity under the 3C condition was 29 mAh / g, which was 44% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not subjected to battery cell evaluation, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 5.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 1.00 μm. The average particle diameter of the solid electrolyte particles was 1.25 times Rmax, the thickness of the solid electrolyte was 6.3 times Rmax, and 5.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Comparative Example 3)
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 4. A battery cell was prepared in the same manner as in Example 4 except that sulfide solid electrolyte particles having an average particle size of 0.20 μm were used and the amount of the input was set to 0.08 times that of Example 1 to form a solid electrolyte layer.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 113 mAh / g (90% of the effective capacity) was Obtained. The average discharge capacity under the 3C condition was 98 mAh / g, which was 87% of the 0.1C condition. Thereafter, when 20 cycles of charge and discharge were repeated at 0.1 C, two of the five batteries could not be charged or discharged due to a short circuit between the electrodes.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 0.80 μm, the thickness of the solid electrolyte layer was 3.5 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 0.20 μm. The average particle diameter of the solid electrolyte particles was 0.25 times Rmax, the thickness of the solid electrolyte was 4.4 times Rmax, and 17.5 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Comparative Example 4)
As shown in Table 1, a positive electrode mixture layer was formed with the same material and blending ratio as in Example 4. A battery cell was prepared in the same manner as in Example 4 except that sulfide solid electrolyte particles having an average particle size of 0.20 μm were used, and the solid electrolyte layer was formed with an input amount 0.55 times that of Example 1.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 61 mAh / g (49% of the effective capacity) was obtained. Obtained. The average discharge capacity under the 3C condition was 31 mAh / g, remaining at 51% of the 0.1C condition. Then, 20 cycles charge / discharge was repeated at 0.1 C, and it was confirmed that there was no short circuit.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined in the same manner as in Example 1 and found to be 0.80 μm. The thickness of the solid electrolyte layer was 25 The average particle diameter of the solid electrolyte particles of the solid electrolyte layer was 0.20 μm. The average particle diameter of the solid electrolyte particles was 0.25 times Rmax, the thickness of the solid electrolyte was 31.3 times Rmax, and 125.0 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

(Comparative Example 5)
LiCoO ₂ (maximum particle diameter 30.0 μm) was used as the positive electrode active material particles. The sulfide solid electrolyte was used as ion conductive auxiliary particles without re-grinding after heat treatment. The positive electrode mixture layer was formed using acetylene black as the conductive auxiliary agent, with the compounding ratio of 80 wt% positive electrode active material particles, 10 wt% ionic conductive auxiliary particles, and 10 wt% conductive auxiliary agent. As shown in Table 1, the ion conductive auxiliary particles used for the electrode mixture layer for the positive electrode were also used as solid electrolyte particles of the solid electrolyte layer, and the input amount was 3.0 times that of Example 1, as shown in Table 1. Similarly, a battery cell was prepared.

  As a result of battery cell evaluation under the conditions of 0.1 C (calculated with an effective capacity of 125 mAh / g) and a charge / discharge end voltage of 4.2 V / 3.0 V, an average discharge capacity of 58 mAh / g on average (46% of the effective capacity) Got. The average discharge capacity under the 3C condition was 23 mAh / g, which was only 40% of the 0.1C condition. Thereafter, when 20 cycles of charge and discharge were repeated at 0.1 C, 4 out of 5 batteries could not be charged or discharged due to a short circuit between the electrodes.

  For one battery that was not evaluated for battery cells, the Rmax formed by the active material particles on the surface of the electrode mixture layer was determined to be 27.0 μm, the thickness of the solid electrolyte layer was 125.0 μm, and the solid electrolyte layer The average particle diameter of the solid electrolyte particles was 3.00 μm. The average particle diameter of the solid electrolyte particles was 0.11 times Rmax, the thickness of the solid electrolyte was 4.6 times Rmax, and 41.7 times that of the solid electrolyte particles. The evaluation results are shown in Table 2.

  Table 1 shows a list of materials and blending ratios of these examples and comparative examples, and Table 2 shows the results. Further, the positive electrode layer and the negative electrode layer are laminated with the solid electrolyte layer interposed therebetween, and at least one of the positive electrode layer and the negative electrode layer includes an electrode mixture layer containing active material particles and ion conductive auxiliary particles. The surface roughness formed by the active material particles on the surface of the electrode mixture layer is Rmax, the average particle diameter of the solid electrolyte particles contained in the solid electrolyte layer is “A”, and the thickness of the solid electrolyte layer is “B” As a measurement result. The all solid lithium ion secondary batteries of these examples were confirmed to satisfy 0.1 × Rmax ≦ “A” <1.0 × Rmax and 5.0 × Rmax ≦ “B” <100 “A”. It was.

  From Examples 1 to 10, the average particle diameter of the solid electrolyte particles used in the solid electrolyte layer is 0.1 times or more and less than 1.0 times Rmax formed by the active material particles on the surface of the electrode mixture layer. When the thickness is not less than 5 times Rmax and not more than 100 times the average particle diameter of the solid electrolyte particles used in the solid electrolyte layer, a large discharge capacity is obtained under the 0.1C condition, and the capacity under the 3C condition with respect to the 0.1C condition. It was confirmed that the ratio was high, that is, the output characteristics were high. Moreover, no short circuit was observed in all examples.

  In Comparative Example 1 in which the average particle diameter of the solid electrolyte particles used for the solid electrolyte layer is less than 0.1 times Rmax formed by the active material particles on the surface of the electrode mixture layer, the discharge capacity under the condition of 0.1 C and 0.1 C The ratio of the capacity under the 3C condition relative to the condition was lower than in all examples.

  In Comparative Example 2 in which the average particle diameter of the solid electrolyte particles used in the solid electrolyte layer is 1.0 times or more of Rmax formed by the active material particles on the surface of the electrode mixture layer, the discharge capacity under the condition of 0.1 C and 0.1 C The ratio of the capacity under the 3C condition relative to the condition was lower than in all examples.

  In Comparative Examples 3 and 5 in which the thickness of the solid electrolyte layer is 5 times or less the Rmax formed by the active material particles on the surface of the electrode mixture layer, there are cases where charging / discharging could not be performed due to a short circuit during the charge / discharge test. It was confirmed that it could not withstand practical use as a secondary battery.

  In Comparative Example 4 in which the thickness of the solid electrolyte layer is 100 times or more the average particle diameter of the solid electrolyte particles used in the solid electrolyte layer, the discharge capacity under the 0.1C condition and the ratio of the capacity under the 3C condition to the 0.1C condition Was lower than in all examples.

  From the comparison of Examples 1-2, when the solid electrolyte contained in the electrode mixture layer is a sulfide rather than an oxide, a larger discharge capacity is obtained under the 0.1C condition, and under the 3C condition with respect to the 0.1C condition. It was confirmed that the capacity ratio of was higher.

  From the comparison of Examples 2 to 4, when Rmax formed by the active material particles on the surface of the electrode mixture layer is less than 1.0 μm, a larger discharge capacity is obtained under the 0.1C condition, and the 3C condition with respect to the 0.1C condition. It was confirmed that the percentage of capacity at was higher.

  From the comparison of Examples 5 to 12, when the thickness of the solid electrolyte layer is less than 50 times the average particle diameter of the solid electrolyte particles used in the solid electrolyte layer, a larger discharge capacity is obtained under the 0.1 C condition. It was confirmed that the ratio of the capacity under the 3C condition to the 1C condition was higher.

  As a result, it was confirmed that according to the embodiment of the present invention, an all-solid lithium ion secondary battery having a high capacity and excellent output characteristics can be obtained.

  The all-solid-state lithium ion secondary battery according to the present invention having a high capacity and excellent output characteristics is suitably used as a power source for portable electronic devices, and is also used as an electric vehicle, a household and an industrial storage battery.

DESCRIPTION OF SYMBOLS 11 Positive electrode collector, 12 Negative electrode collector, 20 Electrode compound layer for positive electrodes, 21 Positive electrode active material particles, 22 Ion conductive auxiliary agent particles, 30 Solid electrolyte layer, 31 Solid electrolyte particle, 40 Negative electrode layer

Claims (4)

The positive electrode layer and the negative electrode layer are laminated with the solid electrolyte layer sandwiched between them.
At least one of the positive electrode layer and the negative electrode layer is an electrode mixture layer containing active material particles and ion conductive auxiliary particles,
When the surface roughness Rmax formed by the active material particles on the surface of the electrode mixture layer on the solid electrolyte layer side is defined,
The average particle diameter of the solid electrolyte particles forming the solid electrolyte layer is 0.1 times or more and less than 1.0 times Rmax,
The all-solid-state lithium ion secondary battery, wherein the thickness of the solid electrolyte layer is not less than 5 times Rmax and less than 100 times the average particle diameter of the solid electrolyte particles forming the solid electrolyte layer.   The all-solid-state lithium ion secondary battery according to claim 1, wherein the ion conductive auxiliary particles include a sulfide solid electrolyte.   The all solid lithium ion secondary battery according to claim 1, wherein the Rmax is less than 1.0 μm.   The all-solid-state lithium ion secondary battery in any one of Claims 1-3 provided with the said solid electrolyte layer of thickness less than 50 times the average particle diameter of the said solid electrolyte particle.

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