JP2016184483A - All solid-state lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all solid-state lithium secondary battery capable of effectively reducing resistance in a lithium secondary battery and suppressing cycle deterioration due to charge/discharge.SOLUTION: In an all solid-state lithium secondary battery, a solid electrolyte layer is arranged between a negative electrode layer and a positive electrode layer. At least one of the negative electrode layer and the positive electrode layer contains active material particles capable of absorbing/desorbing lithium and lithium metavanadate (LiVO) filled between the particles and having deliquescence, and is joined to a collector having electron conductivity by lithium metavanadate.SELECTED DRAWING: Figure 2

Description

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

  An all-solid lithium secondary battery using a non-flammable or flame-retardant solid electrolyte can have high heat resistance and can be made safe, so that the module cost can be reduced. In addition, by repeatedly laminating a bipolar electrode with a positive electrode and a negative electrode on both sides of a metal foil and a solid electrolyte layer, a bipolar battery in which single cells of positive electrode / solid electrolyte / negative electrode are connected in series in one battery pack is formed. can do. In conventional lithium batteries, it is necessary to arrange a plurality of battery packs in series in order to enable high voltage storage of 5 V or higher, but bipolar batteries can achieve a desired high voltage in one battery pack. Therefore, it is possible to reduce the volume and cost of the battery pack exterior and terminals when configuring a high voltage, high capacity power storage system.

  As an example of an all-solid battery using a solid electrolyte and a bipolar battery, Patent Document 1 discloses a battery including a solid electrolyte layer containing a lithium element, a phosphorus element, and a sulfur element between a positive electrode and a negative electrode. ing.

Further, in Patent Document 2, in all solid state batteries and bipolar type batteries, for the purpose of improving battery performance such as resistance reduction and capacity increase, an electron conductive collecting foil in contact with the positive electrode and the negative electrode has a porous structure, A structure in which pores are filled with a solid electrolyte containing active material and sulfur, V ₂ O _{5 and the} like is disclosed.

Patent Document 3 discloses a NASICON structure as a solid electrolyte such as Li _1.2 Al _0.2 Ti _1.8 (PO ₄ ) ₃ or Li _1.5 Al _0.5 Ge _1.5 (PO) _3. A bipolar battery obtained by laminating a plurality of green sheets including a current collecting layer, a positive electrode, a solid electrolyte, and a negative electrode using a lithium-containing phosphoric acid compound having a temperature of 700 ° C. or higher is disclosed.

  In addition, as an example of a lithium secondary battery using an oxide-based solid electrolyte, Patent Document 4 includes a solid electrolyte layer together with a positive electrode and a negative electrode, and includes at least one of the positive electrode, the negative electrode, and the solid electrolyte layer. A battery is disclosed that includes a solid electrolyte filler, one of which is thermally melted near 700 ° C., such as a Li—B—O compound.

JP 2008-103285 A JP 2013-105702 A WO2012 / 020700 JP 2013-084377 A

  In Patent Documents 1 to 4, it is difficult to easily and easily obtain a battery with low resistance.

  That is, in Patent Documents 1 and 2, since the sulfur compound used as the solid electrolyte reacts with oxygen and moisture in the atmosphere, ionic conductivity is reduced and toxic gas is generated, battery production in a controlled space with a low dew point Is required. Moreover, since it is necessary to provide an exterior and a safety mechanism for preventing the inside of the produced battery from coming into contact with the atmosphere, the battery system is increased in size.

  In Patent Documents 3 and 4, since an oxide-based electrolyte is used as the solid electrolyte, the problems as in Patent Documents 1 and 2 are solved. However, in order to reduce the resistance of the battery, 700 at a high temperature is used. In addition to the problem of increasing the size of the battery, the current collection material is required to withstand heating in the atmosphere, and Cu and the current collection material for conventional non-aqueous lithium batteries are required. Al becomes difficult to apply.

  In view of these circumstances, an object of the present invention is to provide an electrode material and a battery configuration for obtaining an all-solid battery and a bipolar battery that have low resistance and can be manufactured by a simple process.

  In order to solve the above problems, the lithium battery of the present invention is an all-solid lithium battery in which a negative electrode layer and a positive electrode layer sandwich a solid electrolyte layer, and at least one of the negative electrode layer and the positive electrode layer occludes / releases lithium. It includes a possible active material particle and lithium metavanadate having deliquescence filled between the particles, and is joined to a metal foil having electronic conductivity by lithium metavanadate.

  According to the present invention, lithium metavanadate having ion conductivity and electron conductivity is present in the voids of the active material particles, and the metal metavanadate enhances the bondability with the metal foil, thereby reducing the internal resistance of the electrode. be able to. In addition, since lithium metavanadate has deliquescent properties, a simple battery manufacturing process in the atmosphere is possible by applying and impregnating a slurry containing water.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing of the lithium secondary battery which concerns on one Embodiment of this invention. 1 is a cross-sectional view of a bipolar lithium secondary battery according to an embodiment of the present invention. It is sectional drawing of the principal part of the lithium secondary battery which concerns on one Embodiment of this invention. It is sectional drawing of the principal part of the lithium secondary battery which concerns on one Embodiment of this invention. It is sectional drawing of the principal part of the lithium secondary battery which concerns on one Embodiment of this invention. The block diagram of the bipolar electrode which joined the positive electrode current collector foil 11 and the negative electrode collector 10 with the deliquescent Li conductive filler 46. FIG. The block diagram of the bipolar electrode which has arrange | positioned metal foil between the positive electrode current collector foil 11 and the negative electrode current collector foil 21. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, components having the same function are denoted by the same reference numerals, and repeated description may be omitted.

  FIG. 1 is a cross-sectional view of a lithium secondary battery according to an embodiment of the present invention. As shown in FIG. 1, the lithium secondary battery 100 of the present invention includes a positive electrode 70, a negative electrode 80, a battery case 30, and a solid electrolyte layer 50. The positive electrode 70 is composed of the positive electrode current collector 10 and the positive electrode mixture layer 40, and the negative electrode 80 is composed of the negative electrode current collector 20 and the negative electrode mixture layer 60.

  FIG. 1 is a cross-sectional view of an all-solid lithium battery comprising a pair of positive electrode, solid electrolyte, and negative electrode. A bipolar structure having a structure in which a positive electrode and a negative electrode active material layer are disposed on both surfaces of a current collector foil. You can also.

FIG. 2 shows a sectional view of the bipolar battery. The bipolar battery 200 of the present invention includes a plurality of positive electrode mixture layers 40, negative electrode mixture layers 60, a battery case 30, and a solid electrolyte layer 50. Outermost positive electrode mixture layer 40 and negative electrode mixture layer 60 of 200 in the figure are connected to positive electrode current collector 10 and negative electrode current collector. An interconnector 90 as a current collector is disposed between the positive electrode mixture layer 40 and the negative electrode mixture layer 60 that are adjacent to each other in the battery case. 3 and 4 are cross-sectional views of the main part of the lithium secondary battery shown in FIGS. 1 and 2 according to an embodiment of the present invention.
<Positive electrode current collector>
The positive electrode current collector 10 is electrically connected to the positive electrode mixture layer 40. As the positive electrode current collector 10, a metal foil having a thickness of 10 μm to 100 μm can be used. The material is preferably a metal that does not form an alloy with lithium and is not oxidized even at the positive electrode operating potential (> 2.5 V). Specific examples include noble metals such as platinum, gold, and indium, aluminum, titanium, stainless steel, nickel, and the like. Among these, aluminum has advantages such as light weight, low cost, and excellent durability.

  The positive electrode current collector preferably has a porous shape in addition to a flat thin film shape. For example, a perforated foil or an expanded metal having a through hole, a foamed metal plate, or a metal fiber sintered body can be used. Moreover, the surface of these foils and plate materials is etched by an appropriate technique to roughen the surface. By adopting a structure in which such a hole is filled with an electrode material, it is possible to obtain a battery having a low battery resistance and a battery capacity that does not decrease with respect to a charge / discharge cycle.

  As the perforated foil, an appropriate mask is applied to the metal foil, and then through holes are formed by performing physical and chemical etching.

  Examples of the foam metal plate include a metal foam plate mainly composed of aluminum, nickel, stainless steel (SUS304, 316, etc.) or titanium. In particular, a sponge-like porous body having pore continuity in the plate vertical direction is desirable. Commercially available foam metal plates include Sumitomo Electric's Celmet (R) (nickel, nickel-chromium alloy), foamed aluminum porous body of Mitsubishi Materials, and ERG Materials and Aerospace's aluminum farm. Can be mentioned.

  Examples of the metal fiber sintered body include aluminum, nickel, stainless steel (SUS304, 316, etc.), and a metal fiber mainly composed of titanium sintered by heating to form a sheet. Commercially available examples include UACJ's aluminum fiber sintered sheet “Full Porous”.

  An appropriate hole size may be any size as long as the electrode active material can penetrate, and specifically, 10 μm to 1000 μm, and more preferably 10 μm to 100 μm. If it is smaller than this, it is difficult for the active material to enter the premises, resulting in high resistance. On the other hand, when the ratio is larger than this, the abundance ratio of the electric conductor in the electrode is lowered, so that the battery resistance is increased, and the cycle reduction due to charge / discharge tends to be remarkable.

It is desirable that the porosity of the metal foil (ratio of the pore volume to the metal foil volume) is 10% to 90%. Furthermore, it is 50% to 90%. When the above-mentioned porosity is low, the active material volume fraction in the battery is lowered and the energy density is lowered. If the porosity is too high, the mechanical strength of the current collector foil is weakened, and the breakage progresses in the battery during use of the battery, so that the cycle characteristics deteriorate. In the case of perforated foil or punching metal, the porosity can be regarded as synonymous with the aperture ratio.
<Negative electrode current collector>
The negative electrode current collector 20 is electrically connected to the negative electrode mixture layer 60. As the negative electrode current collector 20, a metal foil having a thickness of 10 μm to 100 μm can be used. The material is preferably a metal that does not form an alloy with lithium and is not reduced even by the negative electrode operating potential (<2.5 V vs. Li / Li ⁺ ). Specific examples include noble metals such as gold and indium, copper, titanium, nickel and the like. Among these, copper has advantages such as light weight, low cost compared to others, and excellent durability.

  The shape of the negative electrode current collector is desirably a porous shape in addition to a flat thin film shape, similarly to the positive electrode current collector. For example, a perforated foil having a through hole, an expanded metal, or a foamed metal plate can be used. Moreover, the surface of these foils and plate materials is etched by an appropriate technique to roughen the surface. By adopting a structure in which such a hole is filled with an electrode material, it is possible to obtain a battery having a low battery resistance and a battery capacity that does not decrease with respect to a charge / discharge cycle.

  An appropriate hole size may be any size as long as the electrode active material can penetrate, and specifically, 10 μm to 1000 μm, and more preferably 10 μm to 100 μm. If it is smaller than this, it is difficult for the active material to enter the premises, resulting in high resistance. On the other hand, when the ratio is larger than this, the abundance ratio of the electric conductor in the electrode is lowered, so that the battery resistance is increased, and the cycle reduction due to charge / discharge tends to be remarkable.

The porosity of the metal foil is preferably 10% to 90%. Furthermore, it is 50% to 90%. When the porosity is low, the active material volume fraction in the battery is lowered, and the energy density is lowered. When the porosity is too high, the mechanical strength of the current collector foil is weakened, and the breakage progresses in the battery during use of the battery, so that the cycle characteristics deteriorate. In the case of perforated foil or punching metal, the porosity can be regarded as synonymous with the aperture ratio.
<Battery case>
The battery case 30 houses the positive electrode current collector 10, the negative electrode current collector 20, the positive electrode mixture layer 40, the solid electrolyte layer 50, the negative electrode mixture layer 60, and the interconnector 90. The battery case 30 has a cylindrical shape, a flat oval shape, a flat elliptical shape, a square shape, or the like according to the shape of the electrode group composed of the positive electrode mixture layer 40, the solid electrolyte layer 50, and the negative electrode mixture layer 60. The shape can be appropriately selected. The material of the battery case 30 can be selected from materials that are corrosion resistant to non-aqueous electrolytes, such as aluminum, stainless steel, and nickel-plated steel.
<Positive electrode mixture layer>
The positive electrode mixture layer 40 includes positive electrode active material particles 42, a positive electrode conductive agent 43 that can optionally be included, solid electrolyte particles 44 that can optionally be included, and a positive electrode binder that can be optionally included.

As the positive electrode active material particles 42, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , Li ₄ Mn ₅ O ₁₂ , LiMn _2−x M _x O ₂ (where M is At least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ti, and x = 0.01 to 0.2), Li ₂ Mn ₃ MO ₈ (where M is Fe, Li _1-x A _x Mn ₂ O ₄ (where A is Mg, B, Al, Fe, Co, Ni, Cr, at least one selected from the group consisting of Co, Ni, Cμ and Zn) It is at least one selected from the group consisting of Zn and Ca, and x = 0.01 to 0.1), LiNi _1-x M _x O ₂ (where M is a group consisting of Co, Fe and Ga) Selected from That is at least one, and _{x = 0.01~0.2), LiFeO 2,} Fe 2 (SO 4) 3, LiCo 1-x M x O 2 ( however, M is Ni, Fe and Mn At least one selected from the group consisting of x = 0.01 to 0.2), LiNi _1-x M _x O ₂ (where M is Mn, Fe, Co, Al, Ga, Ca and And at least one selected from the group consisting of Mg, x = 0.01 to 0.2), Fe (MoO ₄ ) ₃ , FeF ₃ , LiFePO ₄ , LiMnPO _{4 and the} like. Any of the above materials may be contained alone or in admixture of two or more. In the positive electrode active material particles 42, lithium ions are desorbed in the charging process, and lithium ions desorbed from the negative electrode active material particles in the negative electrode mixture layer 60 are inserted in the discharging process.

  The particle diameter of the positive electrode active material particles 42 is normally defined so as to be equal to or less than the thickness of the positive electrode mixture layer 40. When the positive electrode active material particles include coarse particles having a size equal to or larger than the thickness of the positive electrode mixture layer 40, the coarse particles are removed in advance by sieving classification or wind classification, and the positive electrode active material having a thickness equal to or less than the thickness of the positive electrode mixture layer 40. It is preferable to prepare substance particles.

  Further, since the positive electrode active material particles 42 are generally oxide-based and have high electric resistance, a positive electrode conductive agent 43 for supplementing electric conductivity is used. Examples of the positive electrode conductive agent 43 include carbon materials such as acetylene black, carbon black, graphite, and amorphous carbon. Alternatively, oxide particles exhibiting electronic conductivity such as indium tin oxide (ITO) and antimony tin oxide (ATO) can be used.

  Since both the positive electrode active material particles 42 and the positive electrode conductive agent 43 are usually powders, when not filling an oxide filler 46 having Li conductivity as described later, a binder having a binding ability is mixed with the powder. Thus, it is preferable that the powders are bonded to the positive electrode current collector 10 at the same time. Examples of the positive electrode binder include styrene-butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride (PVDF), and a mixture thereof.

  On the other hand, a Li-containing oxide having deliquescence is used as the Li conductive filler 46 in the electrode for the purpose of enhancing electron conduction, ion conduction in the electrode, and the bonding property with the current collector 10 and the interconnector 90. Can be used. The Li-containing oxide having deliquescence is a filler that conducts ions that are carriers responsible for the battery reaction and has deliquescence. In the present invention, having deliquescence means having the property of deliquescence at normal temperature (5 ° C. or more and 35 ° C. or less) in the atmosphere. An active material particle constituting the electrode or the solid electrolyte layer is obtained by dissolving a Li-containing oxide having deliquescence in a solvent containing water to form a slurry and using it in the production of at least one of a positive electrode, a negative electrode and a solid electrolyte layer, and It becomes possible to form a matrix-like structure in which the voids between the solid electrolyte particles are filled with the Li-containing oxide with a high density. Then, by filling the Li conductive filler composed of this Li-containing oxide at a high density, the Li conduction path is increased, and the resistance in the battery can be reduced. Moreover, since the deliquescent Li-containing oxide functions as an adhesive with respect to the positive electrode current collector 10, the adhesion with the positive electrode mixture layer 40 is increased, and the resistance in the battery can be lowered.

  Further, even when a current collecting material having a through hole is used, an active material or a filler can be densely arranged in the through hole due to the presence of a deliquescent Li-containing oxide that can be easily deformed. As a result, the active material and the filler can be disposed in the holes of the current collector foil having through holes as shown in FIG. In FIG. 5, the metal foil 11 having a through hole is filled with positive electrode active material particles 42, an optional positive electrode conductive agent 43, an optional solid electrolyte particle 44, and a Li-containing oxide 46 having deliquescence. Yes. FIG. 5 shows a configuration in which the metal foil 11 having a through hole and the positive electrode current collector foil 10 are joined by a Li-containing oxide 46. With the above configuration, not only the adhesion between the current collector foil and the positive electrode is increased, but also the supply of electrons and lithium to the active material filled in the metal foil 11 having the through holes is smoothed, and the resistance Can be reduced. Further, expansion / contraction of the entire electrode with respect to expansion / contraction of the active material during charge / discharge is suppressed, and cycle deterioration due to structural collapse can be suppressed. In the figure, the positive electrode material is filled only in the through hole, but the effect is obtained even when the electrode material leaks from the through hole to the solid electrolyte layer 50 side and the positive electrode current collector foil 10 side. It is done. In addition, a part of the solid electrolyte layer 50 may enter the through hole. In the figure, the through-hole is formed in the direction perpendicular to the film, but it is inclined with respect to the vertical direction of the foil, or the hole is branched in the foil and connected to another nearby through-hole. May be. Further, the surface of the through hole may be uneven, and the specific surface area may be increased.

Specific examples of the Li-containing oxide having deliquescence include lithium metavanadate (LiVO ₃ ) and lithium-vanadium oxide containing the same. The ionic conductivity of the deliquescent Li conductive filler 4 is preferably 1 × 10 ⁻⁹ S / cm or more, and more preferably 1 × 10 ⁻⁷ S / cm or more. If the ionic conductivity is 1 × 10 ⁻⁹ S / cm or more, the ionic conductivity between the active material particles and the active material particles or between the active material particles and the solid electrolyte particles can be significantly improved. It is possible to satisfactorily reduce the internal resistance of the secondary battery and ensure a higher discharge capacity. In addition, this ionic conductivity is a value in 25 degreeC.

A positive electrode slurry in which a positive electrode active material particle 42, a positive electrode conductive agent 43, a Li conductive filler 46 and an organic solvent containing a trace amount of water are mixed is attached to the positive electrode current collector 10 by a doctor blade method, a dipping method, a spray method, or the like. Then, the positive electrode can be produced by drying the solvent and press-molding with a roll press. In addition, a plurality of positive electrode mixture layers 40 can be laminated on the positive electrode current collector 10 by performing a plurality of times from application to drying. Further, in order to fill the through hole with the positive electrode constituent material as shown in FIG. 5, the current collector foil having the through hole directly applied to the current collector foil 11 having the through hole or on the positive electrode slurry applied in the form of another sheet. 11 can be placed and impregnated. At this time, by drying under reduced pressure, the filling state in the hole is improved, and a battery having a higher energy density and a lower resistance can be obtained.
<Negative electrode mixture layer>
As the negative electrode according to the present invention, both a metal negative electrode layer made of lithium foil and Li alloy foil and a negative electrode mixture layer 60 made of active material particles can be selected and used.

  The negative electrode mixture layer 60 includes negative electrode active material particles 62, a negative electrode conductive agent 63 that can optionally be included, solid electrolyte particles 64 that can optionally be included, and a negative electrode binder that can be optionally included.

  As the negative electrode active material particles 62, a carbon material capable of reversibly inserting and desorbing lithium ions, Si and SiO which are silicon-based materials, lithium titanate in which some elements are substituted or not substituted, and lithium vanadium composite An oxide, an alloy of lithium and a metal such as tin, aluminum, antimony, or the like is used. The carbon material is made of natural graphite, a composite carbonaceous material in which a film is formed on natural graphite by a dry CVD method or a wet spray method, a resin material such as epoxy or phenol, or a pitch-based material obtained from petroleum or coal. Examples thereof include artificial graphite and non-graphitizable carbon material produced by firing. As the negative electrode active material particles 62, any one of the above materials may be used alone or in admixture of two or more. The negative electrode active material particles 62 undergo lithium ion insertion / desorption reaction or conversion reaction during the charge / discharge process.

  The particle size of the negative electrode active material particles 62 is normally defined so as to be equal to or less than the thickness of the negative electrode mixture layer 60. When the negative electrode active material particles 62 include coarse particles having a size equal to or larger than the thickness of the negative electrode mixture layer 60, the coarse particles are removed in advance by sieving classification, wind classification, or the like, and particles having a thickness of the negative electrode mixture layer 60 or less. Is preferably prepared.

  Examples of the negative electrode conductive agent 63 include carbon materials such as acetylene black, carbon black, graphite, and amorphous carbon.

  Since both the negative electrode active material particles 62 and the negative electrode conductive agent 63 are usually powders, when the above-described Li conductive filler 46 is not filled, a binder having a binding ability is mixed with the powders to bond the powders together. At the same time, it is preferably adhered to the negative electrode current collector 20. Examples of the negative electrode binder include styrene-butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride (PVDF), and a mixture thereof.

On the other hand, for the purpose of enhancing electron conduction, ion conduction, and bonding property with the current collector 20 in the electrode, a Li-containing oxide having deliquescence is used as the Li conductive filler 46 in the electrode as in the positive electrode. Can be used. As the Li-containing oxide having deliquescence that can be used for the negative electrode, lithium metavanadate (LiVO ₃ ) or a lithium-vanadium oxide containing the same can be used as in the positive electrode.

However, in the present invention, it is not always necessary to apply a deliquescent Li conductive filler to the negative electrode, and when a deliquescent Li conductive filler is used for the positive electrode, other fillers may be used. The effect is obtained. As another filler candidate, a Li conductive polymer electrolyte film can also be used. In this case, ether and carbonyl bond-containing polymer compounds such as polyethylene oxide (PEO) and polyerylene carbonate (PEC) can be used as the material. Li salts such as LiPF ₆ , LiBF ₄ , LiFSI, and LiTFSI can be used as a solid solution in the polymer. It is also possible to use a Li conductive hydride material based on LiBH ₄ .

A negative electrode slurry obtained by mixing a negative electrode active material particle 62, a negative electrode conductive agent 63, a Li conductive filler 46, and an organic solvent containing a small amount of water is mixed with the negative electrode current collector 20 and the interferometer by a doctor blade method, a dipping method, a spray method, or the like. After making it adhere to the negative electrode surface of the connector 90, an organic solvent is dried, and a negative electrode can be produced by press-molding with a roll press. In addition, a plurality of negative electrode mixture layers 60 can be laminated on the negative electrode current collector 20 and the interconnector 90 by performing a plurality of times from application to drying.
<Solid electrolyte layer>
As shown in FIGS. 3 and 4, the solid electrolyte layer 50 includes solid electrolyte particles 52 and a binder for binding the solid electrolyte particles 52 as necessary. Alternatively, a polymer electrolyte film having Li conductivity can be used as the solid electrolyte layer 50.

  The layer thickness of the solid electrolyte layer 50 is preferably 1 μm to 1 mm. From the viewpoint of ion conductivity and strength, it is preferably 10 μm to 50 μm, particularly preferably 10 μm to 30 μm. When the layer thickness is smaller than 1 μm, the strength cannot be sufficiently maintained. On the other hand, when the layer thickness exceeds 1 mm, the ion conduction resistance increases, and the energy density in the battery decreases.

  The solid electrolyte layer 50 is provided in a sheet shape between the positive electrode 70 and the negative electrode 80. In order to increase the contact area with the electrode, it is preferable to provide unevenness with a size of 1 μm to 100 μm artificially formed on the surface.

  The surface roughness of the fixed electrolyte layer 50 is preferably an arithmetic average roughness Ra of 0.1 μm to 5 μm. A larger roughness is preferable from the viewpoint of adhesion to the electrode. When the roughness is smaller than 0.1 μm, the junction area with the electrode is small and the interface resistance is increased.

The solid electrolyte particle 52 is not particularly limited as long as it is a solid material that conducts lithium ions. However, it is desirable to include a nonflammable inorganic solid electrolyte from the viewpoint of safety. The same material can be used for the solid electrolyte particles 44 optionally used in the positive electrode mixture layer 40 and the solid electrolyte particles 64 optionally used in the negative electrode mixture layer 60. Examples thereof include oxide solid electrolytes such as perovskite oxides, NASICON oxides, LISICON oxides, and garnet oxides, sulfide solid electrolytes, and β alumina. Examples of the perovskite oxide include Li-La-Ti perovskite oxides such as Li _a La _1-a TiO ₃ and Li _b La _1-b TaO _3. Li-La-Ta-based perovskite type _oxide, in _{Li c La 1-c NbO 3} Li-La-Nb -based perovskite oxide represented as such, and the like (the above formula, 0 <a <1 , 0 <b <1, 0 <c <1). The NASICON-type oxide, for _example, in _{Li m X n Y o P p} O q ( Formula to ShuAkira the _{Li 1 + l Al l Ti 2} -l (PO 4) ₃ or the like crystal, X is, B, It is at least one element selected from the group consisting of Al, Ga, In, C, Si, Ge, Sn, Sb, and Se, and Y is composed of Ti, Zr, Ge, In, Ga, Sn, and Al. And at least one element selected from the group, 0 ≦ l ≦ 1, and m, n, o, p, and q are arbitrary positive numbers). As the LISICON type oxide, for example, Li ₄ XO ₄ -Li ₃ YO ₄ (wherein X is at least one element selected from Si, Ge, and Ti, and Y is P, As And an oxide represented by at least one element selected from V). Examples of the garnet oxide include Li—La—Zr-based oxides such as Li ₇ La ₃ Zr ₂ O ₁₂ . Examples of the sulfide-based solid electrolyte include Li ₂ S—P ₂ S ₅ , Li ₂ S—SiS ₂ , Li _3.25 P _0.25 Ge _0.76 S ₄ , and Li _4-r Ge _1-r P. _Examples include _r S ₄ (where 0 ≦ r ≦ 1), Li ₇ P ₃ S ₁₁ , Li ₂ S—SiS ₂ —Li ₃ PO _{4, and the} like. The sulfide-based solid electrolyte may be either a crystalline sulfide or an amorphous sulfide. These solid electrolyte particles may be used alone or in combination of two or more.

  The particle diameter of the fixed electrolyte particles 52 is preferably 0.01 μm to 10 μm. When the particle diameter exceeds 10 μm, voids are likely to occur between the particles. When the particle size is smaller than 0.01 μm, it may be difficult to compress the particles in the step of forming the solid electrolyte layer 50.

The ionic conductivity of the solid electrolyte particles 52 is preferably 1 × 10 ⁻⁶ S / cm or more, and more preferably 1 × 10 ⁻⁴ S / cm or more. If the ionic conductivity of the solid electrolyte particles 52 is 1 × 10 ⁻⁶ S / cm or more, the resistance in the battery can be kept low by the combined use with the Li conductive filler 45 described later. In addition, this ionic conductivity is a value in 25 degreeC.

  The porosity of the solid electrolyte layer 50 is preferably 0 to 10%. From the viewpoint of ionic conductivity, it is preferably 0 to 5%.

Further, a Li conductive polymer electrolyte film can be used as the solid electrolyte layer 50. In this case, an ether bond-containing polymer compound such as polyethylene oxide (PEO) can be used as the material. Li salts such as LiPF ₆ , LiBF ₄ , LiFSI, and LiTFSI can be used as a solid solution in the polymer.

In addition, the effect of the present invention can be obtained even when a solid electrolyte layer 50 in which the inorganic electrolyte and the polymer electrolyte film are laminated is used.
<Interconnector>
In the bipolar battery of FIG. 2, the interconnector 90, which is a current collecting material disposed between the adjacent negative electrode and positive electrode, has high electron conductivity, no ionic conductivity, the negative electrode mixture layer 60 and the positive electrode. For example, the surface in contact with the mixture layer 40 does not exhibit a redox reaction depending on the potential. Materials that can be used for the interconnector include materials that can be used for the positive electrode current collector 10 and the negative electrode current collector 30 described above. Specific examples include aluminum foil and SUS foil. Alternatively, the positive electrode current collector 10 and the negative electrode current collector 30 can be bonded together by cladding molding and electron conductive slurry.

  FIG. 6A shows a configuration diagram of a bipolar electrode as an interconnector when a current collector foil 11 having a through hole and a negative electrode current collector 10 are joined with a deliquescent Li conductive filler 46. . FIG. 6B is a configuration diagram of a bipolar electrode in which a metal foil is disposed between the positive electrode current collector foil 11 and the negative electrode current collector foil 21 having through holes. By laminating these bipolar electrodes with the solid electrolyte layer 50, it is possible to obtain the bipolar battery 200 having a configuration in which the electrode material is filled in the through holes of the metal foil. This bipolar battery can exhibit low resistance and high cycle characteristics.

  Here, although an example of the manufacturing method of a lithium secondary battery including the structure of FIGS. 3-6 is demonstrated, it can produce also by methods other than this.

  When a material that softens and flows when dissolved in a solvent is used as the Li conductive filler 46, i) a step of mixing at least the positive electrode active material particles 42 and the powder of the Li conductive filler 45, and ii) Li A step of adding a solvent in which the conductive filler is dissolved to form an electrode slurry, iii) a step of applying the electrode slurry onto the positive electrode current collector 10 or the positive electrode current collector 11 having a through hole, and iv) a solvent by heating. The metal foil and the electrode mixture layer are bonded with lithium metavanadate, and the all-solid-state Li secondary battery of the present invention can be manufactured.

In i), the positive electrode active material particles 42 and the Li conductive filler 46 powder are blended in a predetermined amount and mixed using an agate mortar or a ball mill. You may add the solid electrolyte particle 44 and the positive electrode electrically conductive agent 43 as needed. In ii), a solvent capable of dissolving the Li conductive filler 46 to form a slurry is added. In the case of using the deliquescent LiVO ₃ material, a polar solvent containing water can be used as a solvent. In iii), an electrode slurry is applied on the positive electrode current collector 10 or the positive electrode current collector having a through hole by using a blade coater method, a screen printing method, a die coater method, a spray coating method, or the like to form a thin film. Can do. After application, the coating film can be pressed as necessary. In the case of the current collector foil 11 having a through hole, the current collector foil 11 having the through hole may be placed and impregnated in a slurry form coated on another sheet. In iv), heating is performed at a temperature at which the solvent used for the electrode slurry can be removed. By carrying out this heating step under reduced pressure, it is possible to obtain a more precise structure of the electrodes.

  The method for manufacturing the positive electrode 70 has been described above, but this method can be similarly applied to the case of manufacturing the negative electrode 80 or the solid electrolyte layer 50.

  Whether or not it is a lithium secondary battery of the present invention is determined by disassembling the lithium secondary battery, observing its cross section with SEM or TEM, and further analyzing its composition with energy dispersive X-ray analysis (EDX), electronic energy. This can be determined by analysis using loss spectroscopy (EELS) or the like.

  As described above, in the present invention, an all-solid lithium battery in which a negative electrode layer and a positive electrode layer sandwich a solid electrolyte layer, and at least one of the negative electrode layer and the positive electrode layer has active material particles capable of occluding and releasing lithium. And lithium metavanadate having deliquescence filled between the particles, and being joined to the metal foil or the metal foil having a through-hole by lithium metavanadate, lithium having low resistance and high cycle characteristics A secondary battery can be obtained.

The lithium secondary battery obtained by the present invention can be used as an electricity storage device by being connected to a cell controller or a control panel and protected by a casing. According to the present invention, charging / discharging at a higher current is possible, and furthermore, a decrease in power storage performance accompanying a cycle can be suppressed. This power storage device can be disposed on the front or bottom of the vehicle body as a power source for automobiles. Furthermore, it can be used as an industrial power supply to balance power supply and demand.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

(Synthesis of Li ₃ BO ₃ filler)
A hot-melt Li ₃ BO ₃ filler used as a comparative example was synthesized.

Lithium carbonate Li ₂ CO ₃ 11.41 g and boron oxide B ₂ O ₃ 3.58 g were blended and mixed in a planetary ball mill using zirconia balls. After mixing, the mixed powder was added to the alumina crucible and heat-treated at 600 ° C. for 24 hours. As a result of analyzing the crystal structure of the obtained powder by XRD, it was confirmed to be Li ₃ BO ₃ . This was designated as _Li 3 BO ₃ fillers. It was 690 degreeC when melting | fusing point was measured from the suggestive thermal analysis (DTA) measurement. The density was 2.4 g / cm ³ .

(Synthesis of LiVO ₃ filler)
Lithium metavanadate (LiVO ₃ ) was synthesized as a Li conductive filler applied to the positive electrode and the negative electrode.

1.85 g of lithium carbonate (Li ₂ CO ₃ ) and 4.55 g of divanadium pentoxide (V ₂ O ₅ ) were weighed and put into a mortar and mixed until uniform. Subsequently, the obtained mixture was replaced with an alumina crucible having an outer diameter of 60 mm and heat-treated in a box-type electric furnace. In addition, this heat processing was set as the process hold | maintained at 580 degreeC for 10 hours, after making it heat up to 580 degreeC with the temperature increase rate of 10 degree-C / min in an atmospheric condition. After heat treatment, the mixture was cooled to 100 ° C., to obtain a LiVO ₃ as deliquescent Li conductive filler.

(Preparation of solid electrolyte slurry containing Li ₃ BO ₃ )
0.15 g of Li ₃ BO ₃ filler is added to 0.85 g of Li ₇ La ₃ Zr ₂ O ₁₂ (Toshima Seisakusho, hereinafter referred to as LLZO) having an average particle size of 1.5 μm, and 5 wt% ethyl cellulose as a resin binder 0.5 g of a solution (solvent: butyl carbitol acetate) was added and mixed to prepare a solid electrolyte slurry containing Li ₃ BO ₃ .

(Preparation of solid electrolyte slurry containing LiVO ₃ )
To 0.85 g of LLZO having an average particle size of 1.5 μm, 0.15 g of LiVO ₃ filler was added, and a total of 0.5 g of a water-NMP mixed solution was added and mixed to prepare a solid electrolyte slurry.

(Comparative Example 1)
In this comparative example, the Li conductive filler in the positive electrode was Li ₃ BO _3, and an all-solid lithium secondary battery in which a positive electrode mixture layer was applied on an aluminum foil, which is a typical positive electrode current collector, was produced.
(1-1) To 1.5 g of LiCoO ₂ powder having an average particle diameter of 10 μm, 0.5 g of Li ₃ BO ₃ powder is added and mixed especially in a mortar, and then 1.5 g of 5 wt% ethylcellulose solution is mixed. In addition, the mixture was kneaded to prepare a positive electrode slurry.
(1-2) The kneaded positive electrode slurry was screen-coated on a 10 mm diameter Al foil.
(1-3) After drying the solvent at 150 ° C., it was cold-pressed with a hand press.
(1-4) The sample was placed on an alumina plate and heated at 400 ° C. to remove ethyl cellulose. As a result of measuring the weight after cooling, the coating amount was 3 mg / cm ² as LiCoO ₂ weight per 1 cm ² of the electrode.
(1-5) The solid electrolyte layer containing Li ₃ BO ₃ was applied on the positive electrode obtained in (1-4). Thereafter, the solid electrolyte was densified in the same manner as (1-3) and (1-4). When the thickness was measured with a micrometer, it was found that a 10 μm solid electrolyte layer was formed.
(1-6) The side surface of the positive electrode obtained in (1-5) above was masked with an insulator. Subsequently, a polyethylene oxide (PEO) film (thickness 50 μm) containing lithium bistrifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi, (LiFSI)) as a lithium salt on the solid electrolyte layer side, and lithium as a negative electrode The foil was laminated and incorporated into a CR2025 type coin battery.

(Comparative Example 2)
In this comparative example, in contrast to Comparative Example 1 in which the Li conductive filler in the positive electrode was Li ₃ BO ₃ , the positive electrode mixture layer was heat treated at 700 ° C. which is the melting point of Li ₃ BO _3. A battery was produced.
(2-1) In Comparative Example 1, everything was the same as Comparative Example 1 except that the heat treatment temperature of the aluminum foil coated with the positive electrode slurry was changed from 400 ° C. to 700 ° C. shown in (1-3) (1-5). Thus, a lithium secondary battery of Comparative Example 2 was produced.

Example 1
In this example, a lithium secondary battery in which Li conductive filler in the positive electrode was LiVO ₃ was produced.
(3-1) 0.5 g of LiVO ₃ powder is added to 1.5 g of LiCoO ₂ powder having an average particle diameter of 10 μm, and after mixing especially in a mortar, 0.1 g of water is used to deliquesce LiVO _3. Further, the viscosity was adjusted with N-methyl 2-pyrrolidone, and a positive electrode slurry containing a deliquescent filler was prepared.
(3-2) The positive electrode slurry obtained in (3-1) above was applied on an aluminum foil current collector, subjected to heat treatment at 120 ° C. for 30 minutes to remove moisture, and then a circle with a cross-sectional area of 1 cm ² . A positive electrode was obtained by punching into a plate and cold pressing. As a result of measuring the weight after cooling, the coating amount was 3 mg / cm ² as LiCoO ₂ weight per 1 cm ² of the electrode.
(3-3) A solid electrolyte layer containing LiVO ₃ was applied on the positive electrode obtained in (3-2). Thereafter, the solid electrolyte was densified in the same manner as in (3-2).
(3-4) The side surface of the positive electrode obtained in (3-3) above was masked with an insulator. Subsequently, a polyethylene oxide (PEO) film (thickness 50 μm) containing lithium bistrifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi, (LiFSI)) as a lithium salt on the solid electrolyte layer side, and lithium as a negative electrode The foil was laminated and incorporated into a CR2025 type coin battery. This was designated Example 1.

(Example 2)
In this example, a lithium secondary battery in which the Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was a joined body of a porous Al metal body and an Al foil was produced.
(4-1) An Al foil (thickness 20 μm) and an Al foil having a through hole (hole diameter 150 μm, open area 25%) are stacked on a glass plate and closely adhered to the glass plate, and then (3-1) The positive electrode slurry blade coater containing LiVO ₃ prepared in step 1 was applied.
(4-2) The whole glass plate was put in a vacuum dryer, heated to 150 ° C. under reduced pressure, and the positive electrode active material and LiVO ₃ were filled into the through-holes while removing the solvent. When the sample after drying was cut and the cross section was confirmed by SEM, the inside of the hole and the surface of the Al foil were filled with LiCoO ₂ and LiVO ₃ , and further LiVO ₃ entered between the porous Al foil and the Al foil, It was confirmed that both were joined.
(4-3) The side surface of the positive electrode obtained in (4-2) was masked with an insulator. Subsequently, a polyethylene oxide (PEO) film (thickness 50 μm) containing lithium bistrifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi, (LiFSI)) as a lithium salt on the solid electrolyte layer side, and lithium as a negative electrode The foil was laminated and incorporated into a CR2025 type coin battery. This was designated Example 2.

Example 3
In this example, a lithium secondary battery in which the Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was a joined body of a porous SUS304 metal body and SUS304 foil was produced.
(5-1) Example 3 was carried out in the same manner as Example 2 except that SUS304 foil (100 μm thickness) and SUS304 foil having a through hole (pore diameter 150 μm, aperture ratio 25%) were used as the positive electrode current collector. Obtained.

Example 4
In this example, a lithium secondary battery using LiVO _{3 as} the Li conductive filler in the negative electrode and Cu foil as the negative electrode current collector was produced.
(6-1) To 1.4 g of Li ₄ Ti ₅ O ₁₂ powder (manufactured by Aldrich) having a primary particle size of 200 μm, 0.5 g of 0.1 g LiVO ₃ powder is added as acetylene black as a conductive additive, In particular, after mixing in a mortar, 0.1 g of water was added to deliquesce LiVO ₃ , and the viscosity was adjusted with N-methyl 2-pyrrolidone to prepare a negative electrode slurry containing a deliquescent filler.
(6-2) The negative electrode slurry obtained in (6-1) above was applied onto a copper foil current collector having a thickness of 10 μm, subjected to heat treatment at 120 ° C. for 30 minutes to remove moisture, and then the cross-sectional area was 1 cm ^2. The negative electrode was obtained by punching out into a disk shape and cold pressing. As a result of measuring the weight after cooling, the coating amount was 2.7 mg / cm ² as Li ₄ Ti ₅ O ₁₂ weight per 1 cm ² of the electrode.
(6-3) The solid electrolyte layer containing LiVO ₃ was applied on the negative electrode obtained in (6-2). Thereafter, the solid electrolyte was densified in the same manner as in (6-2).
(6-4) The side surface of the negative electrode obtained in (6-3) was masked with an insulator. Subsequently, a polyethylene oxide (PEO) film (thickness 50 μm) containing lithium bistrifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi, (LiFSI)) as a lithium salt on the solid electrolyte layer side, and lithium as a negative electrode The foil was laminated and assembled into a CR2025 type coin battery to form a half cell for evaluating negative electrode characteristics. This was designated Example 4.

(Example 5)
In this example, a lithium secondary battery using LiVO _{3 as} the Li conductive filler in the negative electrode and an Al foil as the negative electrode current collector was produced.
(7-1) Example 5 was obtained as a half cell for evaluating negative electrode characteristics in the same manner as in Example 4 except that Al foil (20 μm thickness) was used as the negative electrode current collector.

(Example 6)
In this example, a lithium secondary battery in which the Li conductive filler in the positive electrode was LiVO ₃ and the negative electrode current collector was a joined body of a porous Al metal body and an Al foil was produced.
(8-1) Al foil (20 μm thick) and (Al foil having a through hole (hole diameter 150 μm, hole area ratio 25%)) are stacked on a glass plate and closely adhered to the glass plate, from above (6-1 The negative electrode slurry blade coater containing LiVO ₃ prepared in (1) was applied.
(8-2) The glass plate was placed in a vacuum dryer, heated to 150 ° C. under reduced pressure, and the positive electrode active material and LiVO ₃ were filled into the through hole while removing the solvent. When dried sample was cut cross section was confirmed by SEM, _Li 4 _Ti 5 _{O 12} and LiVO ₃ are filled on the surface of the hole and the Al foil, further, LiVO ₃ between the porous Al foil and Al foil Invaded and confirmed that both were joined.
(8-3) The side surface of the positive electrode obtained in (8-2) was masked with an insulator. Subsequently, a polyethylene oxide (PEO) film (thickness 50 μm) containing lithium bistrifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi, (LiFSI)) as a lithium salt on the solid electrolyte layer side, and lithium as a negative electrode The foil was laminated and this was incorporated into a CR2025 type coin battery, and Example 6 was obtained as a half cell for evaluating negative electrode characteristics.

(Example 7)
In this example, the pore diameter of the porous metal foil was 150 μm to 5 μm compared to Example 2 in which the Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was a joined body of a porous Al metal body and an Al foil. A lithium secondary battery was prepared.
(9-1) Example 7 was obtained in the same manner as Example 2 except that the hole diameter of the Al foil having through-holes to be used (opening ratio: 25%) was 5 μm.

(Example 8)
In this example, the pore diameter of the porous metal foil was 150 μm to 10 μm compared to Example 2 in which the Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was a joined body of a porous Al metal body and an Al foil. A lithium secondary battery was prepared.
(10-1) Example 8 was obtained in the same manner as Example 2 except that the hole diameter of the Al foil having a through-hole to be used (opening ratio: 25%) was 10 μm.

Example 9
In this example, the pore diameter of the porous metal foil was 150 μm to 1000 μm compared to Example 2 in which the Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was a joined body of a porous Al metal body and an Al foil. A lithium secondary battery was prepared.
(11-1) Example 9 was obtained in the same manner as Example 2 except that the hole diameter of the Al foil having a through hole to be used (opening ratio 25%) was 1000 μm.

(Example 10)
In this example, the pore diameter of the porous metal foil was 150 μm to 2000 μm compared to Example 2 in which the Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was a joined body of a porous Al metal body and an Al foil. A lithium secondary battery was prepared.
(12-1) Example 10 was obtained in the same manner as in Example 2 except that the hole diameter of the Al foil having a through hole to be used (opening ratio: 25%) was 2000 μm.

(Example 11)
In this example, Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was equivalent to the porosity of the porous metal foil compared to Example 2 in which the porous Al metal body and Al foil were joined. A lithium secondary battery with an open area ratio of 25% to 10% was produced.
(13-1) Example 11 was obtained in the same manner as Example 2 except that the aperture ratio of the Al foil having through-holes to be used (pore diameter 150 μm) was 10%.

(Example 12)
In this example, Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was equivalent to the porosity of the porous metal foil compared to Example 2 in which the porous Al metal body and Al foil were joined. A lithium secondary battery with an open area ratio of 25% to 50% was produced.
(14-1) Example 12 was obtained in the same manner as Example 2 except that the aperture ratio of the Al foil having through-holes to be used (pore diameter 150 μm) was set to 50%.

(Example 13)
In this example, Li conductive filler in the positive electrode was LiVO ₃ and the positive electrode current collector was equivalent to the porosity of the porous metal foil compared to Example 2 in which the porous Al metal body and Al foil were joined. A lithium secondary battery with an open area ratio of 25% to 90% was produced.
(15-1) Example 13 was obtained in the same manner as Example 2 except that the aperture ratio of the Al foil (through hole diameter 150 μm) having through-holes used was 90%.

(Comparative Example 3)
In this comparative example, the Li conductive filler in the positive electrode is LiVO ₃ and the positive electrode current collector corresponds to the porosity of the porous metal foil compared to Example 2 in which the porous Al metal body and the Al foil are joined. A lithium secondary battery having an open area ratio of 25% to 95% outside the appropriate value was manufactured.
(16-1) Comparative Example 3 was obtained in the same manner as Example 2 except that the aperture ratio of the Al foil having through-holes to be used (pore diameter 150 μm) was 95%.

(Example 14)
In this example, the Li conductive filler was LiVO ₃ and the current collector was an Al foil positive electrode and joined body, and the Li ₄ Ti ₅ O ₁₂ negative electrode having the Li conductive filler as a polymer electrolyte was combined. A lithium secondary battery was prototyped.
(17-1) PEO-based polymer in which 0.1 g of acetylene black as a conductive auxiliary agent is dissolved in NMP against 1.4 g of Li ₄ Ti ₅ O ₁₂ powder (manufactured by Aldrich) having a primary particle size of 200 μm The negative electrode slurry was obtained by adding electrolyte solution so that a polymer electrolyte might be set to 0.5g, and mixing especially in a mortar.
(17-2) The negative electrode slurry obtained in (17-1) above was coated on a 10 μm thick copper foil current collector, NMP was removed by heat treatment at 150 ° C. for 30 minutes, and then a circle with a cross-sectional area of 1 cm ² . A negative electrode was obtained by punching into a plate and cold pressing. As a result of measuring the weight after cooling, the coating amount was 2.7 mg / cm ² as Li ₄ Ti ₅ O ₁₂ weight per 1 cm ² of the electrode.
(17-3) A solid electrolyte layer containing the polymer electrolyte was applied on the negative electrode obtained in (17-2).
(17-4) The side surfaces of the negative electrode obtained in (17-3) and the positive electrode obtained in (3-3) were masked with an insulator. Subsequently, a polyethylene oxide (PEO) film (thickness 50 μm) containing lithium bistrifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ NLi, (LiFSI)) as a lithium salt was used as the solid electrolyte layer, and this was used as the positive electrode This was assembled into a CR2025 type coin battery with a configuration sandwiched between the negative electrode and the negative electrode.

(Example 15)
In this example, the lithium conductive filler is LiVO ₃ and the current collector is a positive electrode with a porous Al foil, and the Li ₄ Ti ₅ O ₁₂ negative electrode with a Li conductive filler as a polymer electrolyte filler is combined. A secondary battery was prototyped.
(18-1) The same procedure as in Example 14 was performed except that the positive electrode to be used was prepared in (4-2), and an Al foil having a through hole was filled with the positive electrode active material and LiVO _3. Example 15 was obtained.

(Example 16)
In this example, a lithium secondary battery in which the positive electrode manufactured in Example 2 and the negative electrode manufactured in Example 5 were combined was prototyped.
(19-1) The positive electrode to be used was prepared in (4-2), the Al foil having a through hole filled with the positive electrode active material and LiVO ₃ , and the negative electrode including LiVO ₃ prepared in (7-1) Example 16 was made in the same manner as Example 14 except that the Li ₄ Ti ₅ O ₁₂ negative electrode was used.

(Example 17)
In this example, a lithium secondary battery in which the positive electrode produced in Example 2 and the negative electrode produced in Example 6 were combined was prototyped.
(20-1) The positive electrode to be used was prepared in (4-2), the Al foil having a through hole filled with the positive electrode active material and LiVO ₃ , and the negative electrode having the through term prepared in (8-2) Example 17 was made in the same manner as Example 14 except that a Li ₄ Ti ₅ O ₁₂ negative electrode containing LiVO ₃ on an Al foil was used.

(Example 18)
In this example, a positive electrode and a negative electrode using LiVO ₃ as a filler were stacked for four cells, and a lithium secondary battery capable of obtaining a voltage four times that of a single cell in one battery was manufactured.
(21-1) After applying the positive electrode slurry obtained in (3-1) on one side of the aluminum foil and the negative electrode slurry obtained in (6-1) on the other side, the aluminum foil was dried at 120 ° C. for 30 minutes, and hand After uniaxial pressing by pressing, punching was performed to φ10 to obtain a bipolar electrode.
(21-2) One surface of the bipolar electrode was removed, and the weights of the remaining positive electrode and negative electrode were measured. As a result, the positive electrode of the bipolar electrode was 3 mg / cm ² as LiCoO _{2 and} 2.7 mg / cm as Li ₄ Ti ₅ O _12. It was found to be cm ² .
(21-3) Four polymer electrolyte films having a diameter of 20 mm and three bipolar electrodes obtained in (21-2) were alternately laminated so that the polymer electrolyte film was outermost. At this time, alignment was performed so that the centers of the respective layers were aligned. Further, a donut-shaped PTFE sheet (30 μm) having an inner diameter of 10 mm and an outer diameter of 22 mm was sandwiched between the polymer electrolyte films so that the polymer electrolyte films did not contact each other.
(21-4) The positive electrode obtained in (3-2) and the negative electrode obtained in (6-2) were bonded to the laminate obtained in (21-3) from the outside. At this time, the positive electrode and the negative electrode were opposed to each other on both surfaces of the four polymer electrolytes.
(21-5) The laminate obtained in (21-4) was assembled into a CR2025 type coin battery, and this was designated as Example 18.

(Example 19)
In this example, a lithium secondary battery in which four cells of a positive electrode and a negative electrode using LiVO ₃ as a filler and an Al foil having a through-hole are stacked and a voltage four times that of a single cell can be obtained in one battery. Prototyped.
(22-1) The positive electrode slurry obtained in (3-1) and the negative electrode slurry obtained in (6-1) were respectively applied to two aluminum foils (150 μm, opening ratio 50%) having through holes, and 80 Pre-drying was performed at 10 ° C. for 10 minutes. Each sheet is sandwiched between Al foils without through-holes, dried in a vacuum dryer under reduced pressure at 120 ° C for 30 minutes, uniaxially pressed by hand press, then punched to φ10 to obtain a bipolar electrode It was.
(22-2) Implemented in the same manner as in Example 18 except that the bipolar electrode obtained in (22-1), the positive electrode obtained in (4-2), and the negative electrode obtained in (8-2) were used. Example 19 was obtained.

(Example 20)
In this example, a lithium secondary battery in which four cells of a positive electrode and a negative electrode using LiVO ₃ as a filler and an Al foil having a through-hole are stacked and a voltage four times that of a single cell can be obtained in one battery. Of these, a solid electrolyte in which an oxide electrolyte sheet was applied was prototyped.
(23-1) Bipolar lithium secondary batteries were all used in the same manner as in Example 19 except that the solid electrolyte used in the lithium secondary battery was changed from a solid polymer electrolyte sheet to a Li ₇ La ₃ Zr ₂ O ₁₂ sheet (200 μm). Example 20 as a secondary battery was obtained.

(Evaluation of positive electrode half cell)
For the coin-type lithium secondary batteries of Comparative Examples 1 to 3 and Examples 1 to 3 and 7 to 13 that were produced, using a 1480 potentiostat made by Solartron, at a 0.1 C rate (450 μA / cm ² ). After charging, the battery was held at SOC = 100% for 1 hour, and the AC resistance was evaluated using an AC impedance device. The AC resistance was fitted with an appropriate equivalent circuit, and the positive electrode resistance was separated and evaluated. Thereafter, the battery was discharged at a 0.1 C rate. The upper limit potential was 4.25 V, the lower limit potential was 3.0 V, and the charge capacity and discharge capacity were measured. After the charge / discharge was repeated 30 times, the ratio of the initial discharge capacity to the 30th discharge capacity was defined as the capacity retention rate.

(Evaluation of negative electrode half cell)
With respect to the coin-type lithium secondary batteries of Examples 4 to 6, the negative electrode made of Li ₄ Ti ₅ O ₁₂ was used at a 0.1 C rate (460 μA / cm ² ) using a 1480 potentiostat manufactured by Solartron. After charging, the battery was held at SOC = 100% for 1 hour, and the AC resistance was evaluated using an AC impedance device. The AC resistance was fitted with an appropriate equivalent circuit, and the negative electrode resistance was separated and evaluated. Thereafter, the battery was discharged at a 0.1 C rate. The upper limit potential was 2.0 V, the lower limit potential was 1.0 V, and the charge capacity and discharge capacity were measured. After the charge / discharge was repeated 30 times, the ratio of the initial discharge capacity to the 30th discharge capacity was defined as the capacity retention rate.

(Evaluation of battery pack)
The coin-type lithium secondary batteries of Examples 14 to 17 were manufactured using a 1480 potentiostat manufactured by Solartron Co., with a negative electrode made of Li ₄ Ti ₅ O ₁₂ and a positive electrode made of LiCoO _{2 having a} 0.1 C rate ( After charging at 450 μA / cm ² ), SOC was maintained at 100% for 1 hour, and the AC resistance was evaluated using an AC impedance device. The AC resistance was fitted with an appropriate equivalent circuit, and the negative electrode resistance was separated and evaluated. Thereafter, the battery was discharged at a 0.1 C rate. The upper limit potential was 2.7 V and the lower limit potential was 1.45 V, and the charge capacity and discharge capacity were measured. After the charge / discharge was repeated 30 times, the ratio of the initial discharge capacity to the 30th discharge capacity was defined as the capacity retention rate.

(Evaluation of bipolar battery)
Regarding the coin-type lithium secondary batteries of Examples 18 to 20, the 1480 potentiostat made by Solartron was used, and the negative electrode made of Li ₄ Ti ₅ O ₁₂ and the positive electrode made of LiCoO ₂ were used using a solid electrolyte. The charging / discharging at the 0.1 C rate (450 μA / cm ² ) of the four stacked bipolar batteries was examined. After charging, the battery was held at SOC = 100% for 1 hour, and the AC resistance was evaluated using an AC impedance device. The AC resistance was fitted with an appropriate equivalent circuit, and the battery internal resistance was separated and evaluated. Thereafter, the battery was discharged at a 0.1 C rate. The upper limit potential was 10.8 V, the lower limit potential was 5.8 V, and the charge capacity and discharge capacity were measured. After the charge / discharge was repeated 30 times, the ratio of the initial discharge capacity to the 30th discharge capacity was defined as the capacity retention rate.

(Consideration of results)
Table 1 shows the battery configuration outline and battery performance in Comparative Examples 1 to 3 and Examples 1 to 20.

(Consideration of results)
In Comparative Examples 1 and 2, when the positive electrode mixture layer containing the Li ₃ BO ₃ filler was applied on the Al foil, the performance was low regardless of the treatment temperature. In the case of low temperature (Comparative Example 1), Li ₃ BO ₃ having a melting point of 700 ° C. does not dissolve, the ion conduction network in the electrode is insufficient, and in the case of high temperature (Comparative Example 2), Al current collector foil (melting point of 660 ° C.) This is thought to be due to dissolution and side reactions with the positive electrode. On the other hand, the positive electrode formed on the Al foil using deliquescent LiVO ₃ as a filler has improved capacity and greatly reduced resistance. Therefore, LiVO ₃ is an effective packing for forming a solid battery positive electrode using Al foil. It can be said to be an agent.

  When Example 1 is compared with Examples 2 and 3, it can be seen that the use of the porous metal foil is effective in reducing resistance and maintaining the capacity after the cycle test. This is presumably because the positive electrode active material and the filler were disposed in the hole surrounded by the metal, and the volume change accompanying the promotion of electron conduction and charge / discharge was suppressed.

  From the results of Examples 4 to 6, it can be confirmed that the effect of the present invention is observed not only in the positive electrode but also in the negative electrode.

  Example 1 and Examples 7 to 10 are different in the hole diameter of the porous Al foil, and there is an appropriate range of the hole diameter from the comparison of the resistance and capacity retention rate. From this example, the hole diameter is 10 μm to 1000 μm. It turns out that an effect is acquired especially.

  Example 1 and Examples 11 to 13 are different in porosity and aperture ratio of the porous Al foil, and there is an appropriate range in the porosity from the comparison of resistance and capacity maintenance rate. From the example, the effect is confirmed at 10% to 90%. On the other hand, in Comparative Example 3 having a porosity of 95%, a short circuit occurred during charging. From the disassembly evaluation after the test, it can be seen that the porous Al foil is broken inside the battery because the porosity is too high, which is considered to be a cause of the short circuit.

In Examples 14 to 17, a deliquescent LiVO ₃ filler was applied to at least the positive electrode, and appropriate charging / discharging was performed in any of the batteries. In particular, it can be seen that the use of a porous Al foil for the positive electrode improves the cycle characteristics. At this time, if deliquescent LiVO ₃ is applied to the positive electrode, the effect can be confirmed whether the negative electrode filler is a polymer electrolyte or LiVO ₃ .

  Examples 18 to 20 are bipolar batteries in which the electrode of the present invention and an all-solid lithium secondary battery are stacked, but a battery voltage of 10 V or more can be obtained, and any of the materials can be charged and discharged. It was. In particular, it was found that Examples 19 and 20 in which the porous Al foil was filled with the positive electrode and the negative electrode were excellent in cycle characteristics. Although the solid polymer film was used for the solid electrolyte layer in Examples 1 to 19, it can be confirmed that the same effect can be obtained in Example 20 using the oxide solid electrolyte.

  Moreover, even when the structure of the present invention is applied to the negative electrode or the solid electrolyte layer, the Li conductivity of the Li conductive filler is improved, and as a result, a lithium secondary battery having excellent charge / discharge characteristics can be obtained.

In this example, a metal foil having a through-hole was used as the porous current collector, but instead of this, even when a foam metal plate or a metal fiber sintered body was used, by applying the same material and process, The effect as seen in this embodiment can be obtained. Moreover, the same effect can be expected when an electrolyte material other than the present embodiment is applied to the negative electrode filler or the solid polymer layer.

DESCRIPTION OF SYMBOLS 10 Positive electrode current collector foil 11 Positive electrode porous current collector 20 having a through hole Negative electrode current collector foil 21 Negative electrode porous current collector 30 having a through hole 30 Battery case 40 Positive electrode mixture layer 42 Positive electrode active material particle 43 Positive electrode conductive agent 44 Solid electrolyte Particle 46 Li conductive filler 50 Solid electrolyte layer 52 Solid electrolyte particle 60 Negative electrode mixture layer 62 Negative electrode active material particle 63 Negative electrode conductive agent 64 Solid electrolyte particle 70 Positive electrode 80 Negative electrode 90 Interconnector 100 Lithium secondary battery 200 Bipolar lithium secondary Secondary battery

Claims (10)

  An all-solid lithium secondary battery in which a solid electrolyte layer is disposed between a negative electrode layer and a positive electrode layer, wherein at least one of the negative electrode layer and the positive electrode layer is inserted between active material particles capable of inserting and extracting lithium and the particles An all-solid-state lithium secondary battery comprising lithium metavanadate having deliquescence filled and being joined to a current collector having electronic conductivity by lithium metavanadate.   The current collector is a joined body of a porous current collector having a through-hole and a metal foil, and the through-hole is filled with a composite of active material particles and deliquescent lithium metavanadate. An all-solid-state lithium secondary battery.   3. The all solid lithium secondary battery according to claim 2, wherein the porous current collector having the through hole is a perforated foil having a through hole, a foamed metal plate, or a metal fiber sintered body.   4. The all-solid lithium secondary battery according to claim 1, wherein the current collector in contact with the positive electrode is aluminum or stainless steel.   5. The all solid lithium secondary battery according to claim 1, wherein the current collector foil in contact with the negative electrode is aluminum, copper, nickel, or stainless steel.   6. The all-solid lithium secondary battery according to claim 2, wherein the average diameter of the through holes of the porous current collector is 10 μm to 1000 μm.   7. The all-solid lithium secondary battery according to claim 2, wherein the porosity of the porous current collector is 10% to 90%.   8. The all-solid-state lithium secondary battery according to claim 1, wherein the all-solid lithium secondary battery has a configuration of a bipolar battery connected in series in a battery pack. i) mixing the active material particles of at least one of the positive electrode or the negative electrode and the lithium metavanadate powder;
ii) adding a solvent containing water that dissolves lithium metavanadate to form an electrode slurry;
iii) applying an electrode slurry to the current collector surface;
iv) drying the solvent by heating and joining the metal foil and the electrode mixture layer with lithium metavanadate;
The manufacturing method of the all-solid-state lithium secondary battery characterized by the above-mentioned. An electricity storage device comprising the all-solid-state lithium secondary battery according to claim 1.

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