JP2016207326A - Electrode composite manufacturing method and lithium battery manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode composite manufacturing method capable of efficiently manufacturing an electrode composite applicable to a lithium battery, and a lithium battery manufacturing method capable of efficiently manufacturing a lithium battery including the electrode composite.SOLUTION: An electrode composite manufacturing method includes a first step of forming an active material compact 2 having a void, and a second step of putting the active material compact 2 and a liquid material 3X (fluid material) containing a solid electrolyte forming material in a pressure tight case 5 and increasing the pressure in an internal space 54 of the pressure tight case 5 higher than an atmospheric pressure. The second step can obtain an electrode composite by impregnating the liquid material 3X in the void of the active material compact 2. The pressure tight case 5 includes a cylindrical body 51, a filter 52, and a piston 53, and is configured so as to change the pressure in the internal space 54 by moving the piston 53.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for producing an electrode assembly and a method for producing a lithium battery.

  Lithium batteries (including primary batteries and secondary batteries) are used as a power source for many electric devices including portable information devices. The lithium battery includes a positive electrode, a negative electrode, and an electrolyte layer that is disposed between these layers and mediates conduction of lithium ions.

  In recent years, all-solid-state lithium batteries that use a solid electrolyte as a material for forming an electrolyte layer have been proposed as lithium batteries that achieve both high energy density and safety (see, for example, Patent Documents 1 to 3).

  These all solid-state lithium batteries are required to have higher output and higher capacity. In order to obtain a high-power and high-capacity all-solid-state lithium battery, it is necessary to highly control the shape of the positive electrode or negative electrode active material and the shape of the electrolyte layer.

  For this reason, in manufacturing a lithium battery, there is a problem that a high manufacturing technique is required and manufacturing efficiency is low.

JP 2006-277797 A JP 2004-179158 A Japanese Patent No. 4615339

  One of the objects of the present invention is to provide an electrode composite manufacturing method capable of efficiently manufacturing an electrode composite applicable to a lithium battery, and a lithium battery capable of efficiently manufacturing a lithium battery including such an electrode composite. It is to provide a manufacturing method.

Such an object is achieved by the present invention described below.
The method for producing an electrode composite of the present invention includes a first step of forming an active material molded body having voids,
A second step of placing the active material molded body and a liquid material containing a solid electrolyte forming material in a pressure resistant container, and setting the pressure inside the pressure resistant container to be higher than atmospheric pressure;
It is characterized by including.

  Thereby, the electrode composite body applicable to a lithium battery can be manufactured efficiently. As a result, for example, an active material molded body having a small inner diameter of a void can be efficiently filled with a liquid material containing a solid electrolyte forming material, so that an electrode composite applicable to a high-power lithium battery can be efficiently used. Can be manufactured well.

  In the method for producing an electrode assembly of the present invention, it is preferable to change the pressure inside the pressure vessel by changing the volume inside the pressure vessel.

  Thereby, since the pressure inside the pressure vessel can be easily changed, the work of impregnating the liquid material into the voids of the active material molded body can be efficiently performed with a simple and low-cost apparatus.

  In the method for manufacturing an electrode composite according to the present invention, it is preferable that the pressure vessel is provided with a filter through which the liquid material can permeate.

  Thereby, the excess gas remaining inside the pressure vessel can be discharged to the outside. As a result, the gas present in the voids of the active material molded body can be efficiently replaced with the liquid material.

  In the method for producing an electrode composite according to the present invention, the filter preferably includes a porous body.

  As a result, a filter having a relatively uniform size and a high mechanical strength is realized, so even when a pressure higher than the atmospheric pressure is applied to the liquid material placed inside the pressure vessel. A filter that allows the liquid material to pass through while maintaining the pressure is realized.

  In the method for producing an electrode composite according to the present invention, the filter preferably contains a ceramic material.

  As a result, a filter having a particularly high mechanical strength and chemical resistance is realized, so that a sufficiently high pressure can be applied to the inside of the pressure vessel and the filter is hardly affected by the liquid material. .

  In the method for producing an electrode composite of the present invention, it is preferable that the pressure inside the pressure vessel is changed in a state where the active material molded body and the filter are in contact with each other.

  Thereby, the air pushed out from the space | gap of an active material molded object with internal pressurization can transfer to a filter efficiently. As a result, it is possible to efficiently discharge air to the outside of the pressure vessel through the filter while suppressing air from being mixed into the liquid material.

In the method for producing an electrode composite according to the present invention, the pressure vessel is
A cylindrical body having two openings facing each other along an axis;
The filter provided by closing one of the two openings;
A piston provided by closing the other of the two openings and slidable along the axis;
It is preferable to provide.

  Thereby, since the structure of a pressure vessel is simple, this manufacturing method can be performed at low cost.

The method for producing a lithium battery of the present invention includes a third method in which a current collector is joined to one surface of the electrode composite produced by the method for producing an electrode composite of the present invention so as to be in contact with the active material molded body. Process,
A fourth step of providing an electrode composition on the other surface of the electrode composite;
Including
The other surface is characterized in that the active material molded body is not exposed.

  Thereby, a lithium battery provided with the electrode assembly mentioned above can be manufactured efficiently. As a result, for example, a liquid material containing a solid electrolyte forming material can be efficiently filled into an active material molded body having a small inner diameter of the void, and thus a high-power lithium battery can be efficiently produced.

It is a longitudinal cross-sectional view of the lithium secondary battery manufactured by applying the manufacturing method of the electrode assembly which concerns on this invention, and the manufacturing method of a lithium battery. It is a figure for demonstrating the formation method of an active material molded object. It is a figure for demonstrating the manufacturing method of an electrode composite_body | complex. It is a figure for demonstrating the manufacturing method of an electrode composite_body | complex. It is a figure for demonstrating the manufacturing method of an electrode composite_body | complex. It is a figure for demonstrating the manufacturing method of a lithium secondary battery. It is a figure for demonstrating the formation method of an active material molded object. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the lithium secondary battery manufactured by applying the manufacturing method of the lithium battery of this invention. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the lithium secondary battery manufactured by applying the manufacturing method of the lithium battery of this invention. It is a longitudinal cross-sectional view which shows 4th Embodiment of the lithium secondary battery manufactured by applying the manufacturing method of the lithium battery of this invention.

  Hereinafter, a method for producing an electrode assembly and a method for producing a lithium battery according to the present invention will be described with reference to the drawings. Note that the drawings used for explanation may be described by appropriately changing the dimensions and ratios of the constituent elements in order to make the drawings easier to see and understand, but this is for convenience. It is. For convenience of explanation, the upper side of the description is referred to as “upper” and the lower side is referred to as “lower”.

(First embodiment)
In the present embodiment, a method for manufacturing an electrode assembly and a method for manufacturing a lithium battery according to the present invention will be described. Moreover, the lithium secondary battery manufactured by applying the manufacturing method of the electrode assembly and the manufacturing method of the lithium battery according to the present invention will be described.

  First, a lithium secondary battery 100 manufactured by applying an electrode composite manufacturing method and a lithium battery manufacturing method according to the present invention will be described. FIG. 1 is a longitudinal sectional view of a lithium secondary battery 100.

  The lithium secondary battery 100 includes a stacked body 10 and an electrode 20 joined on the stacked body 10. The lithium secondary battery 100 is a so-called all solid-state lithium (ion) secondary battery.

  The laminated body 10 includes a current collector 1, an active material molded body 2, and a solid electrolyte layer 3. Hereinafter, the combined structure of the active material molded body 2 and the solid electrolyte layer 3 is referred to as an electrode composite 4. The electrode assembly 4 is located between the current collector 1 and the electrode 20 and is bonded to each other on a pair of opposing surfaces 4a and 4b. Therefore, the laminate 10 has a configuration in which the current collector 1 and the electrode assembly 4 are laminated.

  The current collector 1 is an electrode for taking out the current generated by the battery reaction, and is provided in contact with the active material molded body 2 on the one surface 4 a of the electrode composite 4.

  The current collector 1 functions as a positive electrode when the active material molded body 2 is composed of a positive electrode active material, and functions as a negative electrode when the active material molded body 2 is composed of a negative electrode active material.

  Moreover, as a forming material (component material) of the current collector 1, for example, copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc ( One metal selected from the group consisting of Zn), aluminum (Al), germanium (Ge), indium (In), gold (Au), platinum (Pt), silver (Ag) and palladium (Pd) And alloys containing two or more metal elements selected from this group.

  The shape of the current collector 1 is not particularly limited, and examples thereof include a plate shape, a foil shape, and a net shape. Further, the joint surface of the current collector 1 with the electrode composite 4 may be smooth or uneven, but the contact area with the electrode composite 4 is maximized. Preferably it is formed.

  The active material molded body 2 is a porous molded body that includes particulate active material particles 21 containing an active material as a forming material, and each of the plurality of active material particles 21 is three-dimensionally connected. is there.

  The active material molded body 2 which is a porous molded body has a plurality of pores. Spaces in the plurality of pores are voids of the active material molded body 2. A portion in which the plurality of pores communicate with each other in a mesh shape inside the active material molded body 2 forms a communication hole. When the solid electrolyte layer 3 enters the communication hole, a wide contact area can be secured between the active material molded body 2 and the solid electrolyte layer 3.

  The active material particles 21 can be either a positive electrode or a negative electrode by appropriately selecting the type of active material forming material. When the current collector 1 is used as a positive electrode, for example, a known lithium oxide can be used as a material for forming the active material particles 21 as the positive electrode active material, and in particular, a lithium double oxide can be preferably used.

  In the present specification, the “lithium double oxide” refers to an oxide that always contains lithium and contains two or more kinds of metal ions as a whole and in which the presence of oxo acid ions is not recognized.

Examples of such lithium double oxides include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li ₂ Mn ₂ O ₃ , LiFePO ₄ , Li ₂ FeP ₂ O ₇ , LiMnPO ₄ , LiFeBO ₃ , Li ₃ V _{2. (PO 4) 3, Li 2} CuO 2, LiFeF 3, Li 2 FeSiO 4, Li 2 MnSiO 4 , and the like. In this specification, solid solutions in which some atoms in the crystal of these lithium double oxides are substituted with other transition metals, typical metals, alkali metals, alkali rare earths, lanthanoids, chalcogenides, halogens, etc. These solid solutions can be used as the positive electrode active material.

Further, when the current collector 1 is a negative electrode, the active material molded body 2 is made of, for example, a lithium composite oxide such as Li ₄ Ti ₅ O ₁₂ or Li ₂ Ti ₃ O ₇ as a negative electrode active material. Can be used.

  By including such a lithium oxide, the active material particles 21 transfer electrons between the plurality of active material particles 21, and transfer lithium ions between the active material particles 21 and the solid electrolyte layer 3. The function as the active material molded body 2 is exhibited well.

  The average particle diameter of the active material particles 21 is preferably 300 nm to 5 μm, more preferably 450 nm to 3 μm, and further preferably 500 nm to 1 μm. When an active material having such an average particle diameter is used, the porosity of the obtained active material molded body 2 can be set within a preferable range. As a result, the surface area in the pores of the active material molded body 2 can be increased, and the contact area between the active material molded body 2 and the solid electrolyte layer 3 can be easily expanded, and the lithium battery using the laminate 10 can be easily increased in capacity. Become.

  Here, the porosity is, for example, (1) the volume (apparent volume) of the active material molded body 2 including pores obtained from the outer dimensions of the active material molded body 2 and (2) the active material molded body. 2 is a value measured based on the following formula (I) from the mass of 2 and (3) the density of the active material constituting the active material molded body 2.

  The porosity is preferably 10% or more and 50% or less, and more preferably 30% or more and 50% or less. Since the active material molded body 2 has such a porosity, the surface area in the pores of the active material molded body 2 is increased, and the contact area between the active material molded body 2 and the solid electrolyte layer 3 is easily expanded. It becomes easy to increase the capacity of the lithium battery using the laminate 10.

  When the average particle size of the active material particles 21 is less than the above lower limit, depending on the type of the forming material of the solid electrolyte layer 3, the active material molded body has a fine pore radius of several tens of nm. It is difficult to allow the liquid material containing the inorganic solid electrolyte precursor to enter the pores, and as a result, it may be difficult to form the solid electrolyte layer 3 that contacts the surface inside the pores. .

  Moreover, when the average particle diameter of the active material particles 21 exceeds the above upper limit, the specific surface area, which is the surface area per unit mass, of the formed active material molded body 2 becomes small, and the active material molded body 2 and the solid electrolyte layer The contact area with 3 may be reduced. Therefore, there is a possibility that sufficient output cannot be obtained in the lithium secondary battery 100. Moreover, since the ion diffusion distance from the inside of the active material particle 21 to the solid electrolyte layer 3 becomes long, the lithium oxide near the center in the active material particle 21 may hardly contribute to the function of the battery.

  The average particle diameter of the active material particles 21 is, for example, after dispersing the active material particles 21 in n-octanol so as to have a concentration in the range of 0.1% by mass to 10% by mass, and then the light scattering particle size. It can measure by calculating | requiring a median diameter using a distribution measuring apparatus (the Nikkiso Co., Ltd. make, nano track UPA-EX250).

  Moreover, although mentioned later in detail, the porosity of the active material molded object 2 is controllable by using the pore making material comprised in a particulate organic substance in the process of forming the active material molded object 2. FIG.

  The solid electrolyte layer 3 is formed in contact with the surface of the active material molded body 2 including the inside of the pores (voids) of the active material molded body 2 using the solid electrolyte as a forming material (constituent material).

The solid _{electrolyte, SiO 2 -P 2 O 5 -Li} 2 O, SiO 2 -P 2 O 5 -LiCl, Li 2 O-LiCl-B 2 O 3, Li 3.4 V 0.6 Si 0.4 O ₄ , Li ₁₄ ZnGe ₄ O ₁₆ , Li _3.6 V _0.4 Ge _0.6 O ₄ , Li _1.3 Ti _1.7 Al _0.3 (PO ₄ ) ₃ , Li _2.88 PO _{3. 73} N _0.14 , LiNbO ₃ , Li _0.35 La _0.55 TiO ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₂ S—SiS ₂ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS _{2 -P 2 S 5, LiPON,} Li 3 N, LiI, LiI-CaI 2, LiI-CaO, LiAlCl 4, LiAlF 4, LiI-Al 2 O 3, LiF-Al 2 O 3, LiBr-Al 2 O 3 , _{i 2 O-TiO 2, La} 2 O 3 -Li 2 O-TiO 2, Li 3 NI 2, Li 3 N-LiI-LiOH, Li 3 N-LiCl, Li 6 NBr 3, LiSO 4, Li 4 SiO 4 _{, Li 3 PO 4 -Li 4 SiO} 4, Li 4 GeO 4 -Li 3 VO 4, Li 4 SiO 4 -Li 3 VO 4, Li 4 GeO 4 -Zn 2 GeO 2, Li 4 SiO 4 -LiMoO 4, LiSiO Examples include oxides such as _4- Li ₄ ZrO ₄ , sulfides, halides, and nitrides. The solid electrolyte may be crystalline or amorphous. Further, in the present specification, solid solutions in which some atoms of these compositions are substituted with other transition metals, typical metals, alkali metals, alkali rare earths, lanthanoids, chalcogenides, halogens, and the like may be used as solid electrolytes. it can.

  The solid electrolyte that is a constituent material of the solid electrolyte layer 3 is generated by firing (heating) a precursor of the solid electrolyte. At the time of firing, the generated solid electrolyte constitutes a granular body 31 composed of secondary particles formed by granulating the primary particles. Therefore, although the solid electrolyte layer 3 is provided in contact with the surface of the active material molded body 2 including the inside of the voids of the active material molded body 2, the solid electrolyte layer 3 is configured by an aggregate of the granular bodies 31. As with the active material molded body 2, it is also composed of a porous body.

The ionic conductivity of the solid electrolyte layer 3 is preferably 5 × 10 ⁻⁵ S / cm or more, and more preferably 1 × 10 ⁻⁵ S / cm or more. Since the solid electrolyte layer 3 has such ionic conductivity, ions contained in the solid electrolyte layer 3 at a position away from the surface of the active material molded body 2 reach the surface of the active material molded body 2, and the active material It becomes possible to contribute to the battery reaction in the molded body 2. Therefore, the utilization factor of the active material in the active material molded body 2 is improved, and the capacity can be increased. At this time, if the ionic conductivity is less than the above lower limit, depending on the type of the solid electrolyte layer 3, only the active material in the vicinity of the surface layer on the surface facing the counter electrode in the active material molded body 2 contributes to the battery reaction. Capacity may be reduced.

  The “ionic conductivity of the solid electrolyte layer 3” refers to the “bulk conductivity” that is the conductivity of the inorganic electrolyte itself that constitutes the solid electrolyte layer 3, and the crystal in the case where the inorganic electrolyte is crystalline. It refers to the “total ionic conductivity” which is the sum of the “grain boundary ionic conductivity” which is the conductivity between particles.

  The ionic conductivity of the solid electrolyte layer 3 is determined by, for example, pressing a solid electrolyte powder into a tablet shape at 624 MPa and sintering it at 700 ° C. for 8 hours in an air atmosphere. In addition, a platinum electrode having a diameter of 0.5 cm and a thickness of 100 nm is formed as a specimen, and then measured by an AC impedance method. For example, an impedance analyzer (manufactured by Solartron, model number SI1260) is used as the measuring device.

  The laminate 10 may contain an organic material such as a binder that joins the active materials and a conductive aid for ensuring the conductivity of the active material molded body 2, but in this embodiment, When the active material molded body 2 is molded, the active material molded body 2 is molded without using a binder, a conductive auxiliary agent, or the like, and is substantially composed of only an inorganic substance. Specifically, in this embodiment, the mass reduction rate when the electrode assembly 4 (the active material molded body 2 and the solid electrolyte layer 3) is heated at 400 ° C. for 30 minutes is 5% by mass or less. . The mass reduction rate is more preferably 3% by mass or less, further preferably 1% by mass or less, and particularly preferably no mass reduction is observed or an error range. Since the electrode composite 4 has such a mass reduction rate, the electrode composite 4 is vaporized by being burned or oxidized under a predetermined heating condition or a substance such as a solvent or adsorbed water that evaporates under a predetermined heating condition. An organic matter will be contained only 5 mass% or less with respect to the whole structure.

  The mass reduction rate of the electrode assembly 4 is determined by heating the electrode assembly 4 under predetermined heating conditions by using a differential thermal-thermogravimetric simultaneous measurement device (TG-DTA), and heating the electrode assembly 4 under predetermined heating conditions. The mass of the electrode assembly 4 can be measured and calculated from the ratio of the mass before heating to the mass after heating.

In the laminate 10 of the present embodiment, the active material molded body 2 has communication holes in which a plurality of pores communicate with each other in a mesh shape, and the solid portion of the active material molded body 2 also forms a network structure. doing. For example, LiCoO ₂ that is a positive electrode active material is known to have anisotropy in the electronic conductivity of crystals. Therefore, when trying to form an active material molded body using LiCoO ₂ as a forming material, a structure in which pores are extended in a specific direction, such as forming pores by machining, Depending on the direction of the electron conductivity, it may be difficult to conduct electrons inside. However, if the pores are connected in a network shape like the active material molded body 2 and the solid portion of the active material molded body 2 has a network structure, the anisotropy of the electron conductivity or ion conductivity of the crystal Regardless, an electrochemically lubricious continuous surface can be formed. Therefore, good electronic conduction can be ensured regardless of the type of active material used.

  Moreover, in the laminated body 10 of this embodiment, since the electrode assembly 4 is the above structures, the addition amount of the binder and conductive support agent contained in the electrode composite 4 can be suppressed, The capacity density per unit volume of the laminate 10 is improved as compared with the case where a conductive additive is used.

  Therefore, the lithium secondary battery 100 having the stacked body 10 has an improved capacity per unit volume and higher output than other lithium secondary batteries not having the stacked body 10. It has become.

  In the lithium secondary battery 100, the electrode 20 is bonded to the other surface 4 b of the electrode assembly 4. The electrode 20 is provided in contact with the solid electrolyte layer 3 without being in contact with the active material molded body 2. With such a configuration, in the lithium secondary battery 100, the electrode 20 and the current collector 1 can be prevented from being connected via the active material molded body 2, that is, a short circuit can be prevented. Therefore, the solid electrolyte layer 3 also functions as a short-circuit prevention layer that prevents the occurrence of a short circuit in the lithium secondary battery 100.

  The electrode 20 functions as a negative electrode when the active material molded body 2 is composed of a positive electrode active material, and functions as a positive electrode when the active material molded body 2 is composed of a negative electrode active material.

  As a forming material (constituent material) of the electrode 20, for example, lithium (Li) may be used when the electrode 20 is a negative electrode, and for example, aluminum (Al) may be used when the electrode 20 is a positive electrode.

  Although the thickness of the electrode 20 is not specifically limited, For example, it is preferable that they are 1 micrometer or more and 100 micrometers or less, and it is more preferable that they are 20 micrometers or more and 50 micrometers or less.

Next, the manufacturing method of the electrode assembly 4 will be described.
First, the process (1st process) which forms the active material molded object 2 is demonstrated. By heating the active material particles 21 in the form of a plurality of particles, they are three-dimensionally connected to obtain an active material molded body 2 made of a porous body.

  For example, as shown in FIG. 2, the active material molded body 2 compresses a mixture of a plurality of active material particles 21 using a molding die F having a space corresponding to the shape of the active material molded body 2 to be formed. (See FIG. 2 (a)), and then the obtained compression-molded product can be obtained by heat treatment (see FIG. 2 (b)).

  The heat treatment in the first step is preferably performed at a processing temperature of 850 ° C. or higher and lower than the melting point of the lithium oxide to be used. Thereby, the molded object integrated by sintering the active material particles 21 can be obtained reliably. By performing heat treatment in such a temperature range, the resistivity of the obtained active material molded body 2 can be preferably 700 Ω / cm or less without adding a conductive auxiliary. Thereby, the obtained lithium secondary battery 100 is provided with sufficient output.

  At this time, if the treatment temperature is less than 850 ° C., depending on the type of lithium oxide used, not only does the sintering proceed sufficiently, but the electron conductivity itself in the crystal of the active material itself decreases, so that the obtained lithium The secondary battery 100 may not be able to obtain a desired output.

  Further, when the treatment temperature exceeds the melting point of the lithium oxide, lithium ions are excessively volatilized from within the crystal of the lithium oxide, resulting in a decrease in the electronic conductivity of the lithium oxide, resulting in an electrode composite. The capacity of 4 may be reduced.

  Therefore, in order to obtain an appropriate output and capacity, the treatment temperature is preferably 850 ° C. or higher and lower than the melting point of the lithium oxide, more preferably 875 ° C. or higher and 1000 ° C. or lower, and 900 ° C. or higher and 920 ° C. or lower. More preferably.

  The heat treatment in the first step is preferably performed for 5 minutes to 36 hours, more preferably 4 hours to 14 hours.

  By performing the heat treatment as described above, the growth of grain boundaries in the active material particles 21 and the sintering between the active material particles 21 proceed, so that the resulting active material molded body 2 can easily maintain its shape, The amount of binder added to the active material molded body 2 can be reduced. Moreover, since a bond is formed between the active material particles 21 by sintering and an electron transfer path between the active material particles 21 is formed, the amount of the conductive additive added can also be suppressed.

As a material for forming the active material particles 21, LiCoO ₂ can be suitably used. Thereby, the said effect can be exhibited more notably. That is, the active material molded body 2 integrated by sintering the active material particles 21 can be obtained more reliably.

  In addition, the obtained active material molded body 2 is constituted by communication holes in which a plurality of pores communicate with each other in a mesh shape inside the active material molded body 2.

  Further, an organic polymer compound such as polyvinylidene fluoride (PVdF) or polyvinyl alcohol (PVA) may be added to the forming material used for forming the active material particles 21 as a binder. These binders are combusted or oxidized in the heat treatment in the first step, and the amount thereof is reduced.

In addition, it is preferable to add a particulate pore-forming material using a polymer or carbon powder as a forming material for pores at the time of compacting. By mixing these pore formers, it becomes easy to control the porosity of the active material molded body 2. Such a pore former is decomposed and removed by combustion or oxidation during heat treatment, and the amount of the resulting active material molded body 2 is reduced.
The average particle diameter of the pore former is preferably 0.5 μm or more and 10 μm or less.

  Furthermore, the pore former preferably includes particles (first particles) whose material is a deliquescent material. Since the water generated around the first particles by deliquescent of the first particles functions as a binder that joins the particulate lithium oxide, until the particulate lithium oxide is compression-molded and heat-treated, The shape can be maintained. Therefore, an active material molded body can be obtained without adding another binder or while reducing the amount of the binder added, and a high-capacity electrode composite can be easily obtained.

  As such 1st particle | grains, the particle | grains which use polyacrylic acid as a forming material can be mentioned.

  Moreover, it is preferable that the pore former further includes particles (second particles) whose material is a material having no deliquescence. The pore former containing such second particles is easy to handle. Moreover, although it is only 1st particle | grains, the porosity of an active material molded object may deviate from a desired setting value according to the moisture content around a pore forming material, but it does not deliquesce as a pore forming material. By including the particles at the same time, it is possible to suppress a gap in porosity.

  Note that the first step can also be performed by other methods. As an example, a method using a slurry will be described with reference to FIG.

  First, a binder is dissolved in a solvent, and active material particles 21 are dispersed therein to prepare a slurry 26. The slurry 26 may contain a dispersant such as oleylamine.

  Thereafter, a mold F2 having a bottom F21 having a recess F25 and a lid F22 is prepared, and after slurry 26 is dropped into the recess F25, the bottom F21 is covered with the lid F22.

  The total content of the active material particles 21 in the slurry 26 is preferably 10% by mass to 60% by mass, and more preferably 30% by mass to 50% by mass. Thereby, the active material molded object 2 which has a preferable porosity will be obtained.

  Although it does not specifically limit as a binder, A cellulose type binder, an acrylic binder, a polyvinyl alcohol type binder, a polyvinyl butyral type binder, etc. other than a polycarbonate are mentioned, Among these, it uses combining 1 type, or 2 or more types. Can do.

  Further, the solvent is not particularly limited, but is preferably an aprotic solvent, for example, whereby deterioration of the active material particles 21 due to contact with the solvent can be reduced.

  Specific examples of such an aprotic solvent include butanol, ethanol, propanol, methyl isobutyl ketone, toluene, xylene and the like, and this single solvent or mixed solvent can be used as a solvent.

  Next, the slurry 26 containing the active material particles 21 is heated. Thereby, while drying the slurry 26, the active material particles 21 contained in the slurry 26 can be sintered, and the active material molded object 2 is obtained.

  The heating temperature for heating the slurry 26 is set in the same manner as the conditions for heat-treating the compression-molded product described above.

  Furthermore, the heating of the slurry 26 is preferably performed in multiple stages where the temperature condition is increased stepwise. Specifically, after drying at room temperature, the slurry 26 is heated from room temperature to 300 ° C. for 2 hours, to 350 ° C. for 0.5 hour. It is preferable that the temperature is raised to 1000 ° C. for 5 hours over 2 hours, and then the concave portion F25 is covered with the lid portion F22 and fired at 1000 ° C. for 8 hours. By raising the temperature under such conditions, the binder contained in the solvent can be surely burned off.

  The active material molded object 2 can be obtained using a slurry by passing through the above processes.

  Next, the process (2nd process) which forms the electrode composite 4 using the active material molded object 2 formed at the 1st process mentioned above is demonstrated.

  First, the pressure vessel 5 is prepared. The pressure vessel 5 includes a tubular body 51 having a tubular shape, a filter 52, and a piston 53 slidable along the axis of the tubular body 51, and the pressure of the internal space 54 defined by these. Is a container that can be maintained in a state higher than atmospheric pressure.

  The pressure vessel 5 is used for a process in which the active material molded body 2 and a liquid material 3X containing a solid electrolyte forming material are accommodated and the active material molded body 2 is impregnated with the liquid material 3X. By this treatment, the solid electrolyte layer 3 formed from the liquid material 3X is finally formed so as to be in contact with the surface of the active material molded body 2 including the inside of the voids of the active material molded body 2.

  Since the pressure vessel 5 according to this embodiment has a simple structure, the manufacturing method can be performed at low cost.

  The cylindrical body 51 has a cylindrical shape having an axis in the vertical direction in FIG. 3, and includes an opening 511 on the lower end side of the axis and an opening 512 on the upper end side. Therefore, the opening 511 and the opening 512 are opposed to each other in the direction along the axis.

  The shape of the cylindrical body 51 is not particularly limited except that it is cylindrical. For example, a cylindrical shape having a circular cross section perpendicular to the axis or a cylindrical shape having a polygonal cross section may be used.

  The constituent material of the cylindrical body 51 is not particularly limited as long as it is a material having airtightness and mechanical strength that can withstand the pressure applied to the internal space 54. For example, a metal material such as stainless steel or aluminum, Examples thereof include a ceramic material such as alumina, a resin material such as an acrylic resin, and an epoxy resin.

  The filter 52 is provided so as to close the opening 511 of the cylindrical body 51. Thereby, the clearance gap between the filter 52 and the inner wall of the cylindrical body 51 has liquid-tightness.

  The filter 52 is configured to allow the gas and the liquid material 3 </ b> X contained in the internal space 54 to pass between the internal space 54 and the external space 55 of the pressure-resistant container 5. Thereby, excess gas remaining in the internal space 54 can be discharged to the external space 55. As a result, the gas present in the voids of the active material molded body 2 can be efficiently replaced with the liquid material 3X.

  Further, it is possible to easily determine whether or not the voids of the active material molded body 2 can be filled with the liquid material 3X by allowing the filter 52 to pass through the liquid material 3X. That is, when the active material molded body 2 is positioned in contact with the filter 52, when the liquid material 3X is filled in the gap of the active material molded body 2, a part of the liquid material 3X permeates the filter 52. As a result, it leaks into the external space 55. Therefore, by confirming that the liquid material 3X leaks from the filter 52, it can be indirectly confirmed that at least a part of the gap in the active material molded body 2 is filled with the liquid material 3X. As a result, the impregnation operation of the liquid material 3X can be performed more efficiently.

  Although the constituent material of the filter 52 is not specifically limited, For example, a porous body, a woven fabric, a nonwoven fabric, a net | network, a granular material etc. are mentioned. Among these, the filter 52 containing a porous body is preferably used. Many porous bodies have communication holes with relatively uniform sizes and high mechanical strength. For this reason, even when a pressure higher than the atmospheric pressure is applied to the liquid material 3X placed in the internal space 54 by using a filter containing a porous body, the liquid material is maintained in a state in which the pressure is maintained. A filter 52 capable of transmitting 3X is realized.

  The filter 52 is more preferably one containing a ceramic material. Since the ceramic material has particularly high mechanical strength and chemical resistance, a sufficiently high pressure can be applied to the internal space 54 of the pressure vessel 5 in the process described later, and it is difficult to be attacked by the liquid material 3X. . For this reason, this high pressure can be used as a driving force to efficiently push the liquid material 3X into the voids of the active material molded body 2 accommodated in the internal space 54. As a result, it is possible to increase the probability that the liquid material 3X is distributed to every corner in the gap of the active material molded body 2.

  Examples of ceramic materials include various oxide ceramics such as alumina, zirconia, titania, magnesia, and silica, various nitride ceramics such as aluminum nitride, titanium nitride, and boron nitride, aluminum carbide, and titanium carbide. Such various carbide-based ceramics can be mentioned.

  The piston 53 is a member that is provided so as to close the opening 512 of the cylindrical body 51 and is slidable along the inner wall surface of the cylindrical body 51.

  Therefore, the volume of the internal space 54 of the pressure vessel 5 can be reduced by sliding the piston 53 closer to the filter 52. Thereby, the pressure of the internal space 54 can be raised.

  On the other hand, by sliding the piston 53 away from the filter 52, the volume of the internal space 54 of the pressure vessel 5 can be increased. Thereby, the pressure of the internal space 54 can be reduced.

  Note that the gap between the piston 53 and the inner wall surface of the cylindrical body 51 has air tightness and liquid tightness.

  Thus, by changing the volume of the internal space 54 using the piston 53, the pressure of the internal space 54 can be easily changed. For this reason, the operation | work which impregnates the liquid material 3X in the space | gap of the active material molded object 2 can be efficiently performed with a simple and low-cost apparatus. Further, by operating the piston 53, the pressure in the internal space 54 can be adjusted to a desired value.

  The material of the piston 53 is not particularly limited as long as it is a material having airtightness and mechanical strength that can withstand the pressure applied to the internal space 54. For example, the same material as that of the cylindrical body 51 is used.

  The configuration of the pressure vessel 5 is not limited to that described above, and any pressure vessel may be used as long as it can accommodate the active material molded body 2 and the liquid material 3X.

  As shown in FIG. 3A, the active material molded body 2 and the liquid material 3X containing the solid electrolyte forming material are placed in the internal space 54 of the pressure vessel 5. In this way, by allowing the active material molded body 2 and the liquid material 3X to coexist in the internal space 54, for example, a certain amount of the liquid material 3X can be formed in the gap (communication hole) of the active material molded body 2 by using a capillary phenomenon as a driving force. ). However, it is difficult to impregnate the liquid material 3X into every corner of the gap of the active material molded body 2. For this reason, in the process mentioned later, it is preferable to forcibly impregnate by applying a pressure.

  In addition to the solid electrolyte precursor, the liquid material 3X may include a solvent in which the solid electrolyte precursor is soluble. When the liquid material 3X contains a solvent, the solvent may be appropriately removed after this step and before firing. For the removal of the solvent, a method known in the art such as heating, reduced pressure, and air blowing, or a method combining two or more types can be employed.

  Thus, since the solid electrolyte layer 3 is formed using the fluid material 3X having fluidity, the solid electrolyte layer 3 is also formed on the inner surfaces of the pores of the fine active material molded body 2. Therefore, the contact area between the active material molded body 2 and the solid electrolyte layer 3 can be increased, and the output of the lithium secondary battery 100 can be increased.

Examples of the solid electrolyte precursor include the following (A), (B), and (C).
(A) A composition having a metal atom contained in an inorganic solid electrolyte in a proportion according to the composition formula of the inorganic solid electrolyte and having a salt that becomes an inorganic solid electrolyte by oxidation

(B) The composition which has a metal alkoxide which contains the metal atom which an inorganic solid electrolyte has in the ratio according to the composition formula of an inorganic solid electrolyte

(C) Inorganic solid electrolyte fine particles, or a dispersion in which fine particle sol containing metal atoms of inorganic solid electrolyte in a proportion according to the composition formula of the inorganic solid electrolyte is dispersed in a solvent, or (A) or (B)

  In addition, the salt contained in (A) contains a metal complex. Moreover, (B) is a precursor in the case of forming an inorganic solid electrolyte using a so-called sol-gel method. In (A) and (B), the granular material 31 is produced | generated by reaction of a precursor, and in (C), the granular material 31 is produced | generated by removing a dispersion medium.

  In addition to the active material molded body 2 and the liquid material 3X, the internal space 54 may contain air, various gases, or the like.

  Next, as shown in FIG. 3B, the piston 53 is moved so that the piston 53 comes close to the filter 52. Thereby, a pressure larger than the atmospheric pressure is applied to the internal space 54.

  Since a pressure exceeding atmospheric pressure is also applied to the liquid material 3X, the liquid material 3X enters into the gap as the air escapes and contracts in the gap of the active material molded body 2. And the air in a space | gap is discharged | emitted from the space | gap of the active material molded object 2 so that it may be extruded by the liquid material 3X. Thereby, the active material molded object 2 which impregnated the liquid material 3X in the space | gap is obtained (refer Fig.4 (a)).

  In the present embodiment, since the liquid material 3X is impregnated while applying a pressure exceeding the atmospheric pressure in this way, the liquid material 3X is also efficiently applied to the active material molded body 2 including a void having a smaller inner diameter than the conventional one. It can be impregnated. For this reason, according to this embodiment, it becomes easy to enlarge the contact area of the active material molded object 2 and the solid electrolyte layer 3, and the high output of the lithium secondary battery 100 can be achieved. Furthermore, since the solid electrolyte layer 3 can be spread to every corner of the gap of the active material molded body 2, the capacity of the lithium secondary battery 100 can be increased.

  In addition, since the pressure resistant container 5 according to the present embodiment includes the filter 52, the air in the gap of the active material molded body 2 is discharged to the external space 55 through the filter 52. For this reason, the air in the gap can be easily replaced with the liquid material 3X. As a result, it is possible to increase the probability that the liquid material 3X is distributed to every corner in the gap of the active material molded body 2.

  The positional relationship between the active material molded body 2 and the liquid material 3X in the pressure vessel 5 is not particularly limited, but is preferably set at a position where the active material molded body 2 is in contact with the filter 52. Thereby, in this process, the internal space 54 is pressurized, the liquid material 3X enters into the gap of the active material molded body 2, and the air pushed out from the gap is in contact with the active material molded body 2. The filter 52 can be efficiently transferred. As a result, air can be efficiently discharged to the external space 55 via the filter 52 while suppressing air from being mixed into the liquid material 3X.

  In addition, the filter 52 according to the present embodiment transmits not only air but also the liquid material 3X. For this reason, the liquid material 3 </ b> X that has entered the gap of the active material molded body 2 passes through the gap and is discharged to the external space 55 through the filter 52. Therefore, by confirming that the liquid material 3X is discharged from the filter 52, it can be indirectly confirmed that the liquid material 3X is filled so as to pass through the voids of the active material molded body 2. As a result, the impregnation operation of the liquid material 3X can be performed more efficiently.

  From the above viewpoint, the pore size of the filter 52 is set to a pore size that allows the liquid material 3X not to pass through when the pressure is lower than atmospheric pressure, but allows the liquid material 3X to pass through when a pressure higher than atmospheric pressure is applied. Is preferred. Thus, the liquid material 3X can be stored before pressure is applied to the internal space 54, and the filter 52 that can transmit the liquid material 3X can be realized after pressure is applied.

  Since such a pore diameter is appropriately adjusted according to the composition of the liquid material 3X, the constituent material of the filter 52, and the like, it cannot be generally specified, but is, for example, about 3 nm to 10 μm.

  The pressure applied to the internal space 54 is not particularly limited as long as it is greater than atmospheric pressure, but is preferably set to 101% to 2000% of atmospheric pressure, more preferably 110% to 1000% of atmospheric pressure. The

  When the atmospheric pressure is 100 kPa, the pressure applied to the internal space 54 is preferably set to 10.1 MPa to 200 MPa, more preferably 11 MPa to 100 MPa.

  By setting the pressure applied to the internal space 54 within the above range, the pressure resistance of the pressure vessel 5 is increased more than necessary while the liquid material 3X is impregnated in the gap of the active material molded body 2 in a relatively short time. You can avoid that.

  In addition, you may be made to perform this process in multiple times as needed. That is, after performing this process and impregnating the liquid material 3X in the voids of the active material molded body 2, the active material molded body 2 is taken out from the pressure vessel 5 and the liquid material 3X is dried. You may make it perform this process by putting the body 2 and the liquid material 3X in the internal space 54.

  Next, heat treatment for firing the liquid material 3X is performed. Thereby, the liquid material 3X is dried and fired, and the granular material 31 is generated. The plurality of granular bodies 31 are sintered or connected to form the solid electrolyte layer 3 (see FIG. 4B).

The firing of the liquid material 3X is preferably performed at a temperature lower than the heat treatment for obtaining the active material molded body 2 described above in an air atmosphere. Specifically, the baking temperature is preferably in the temperature range of 300 ° C. or higher and 700 ° C. or lower. By firing, an inorganic solid electrolyte is produced from the precursor, and the solid electrolyte layer 3 is formed. In particular, Li _0.35 La _0.55 TiO ₃ can be suitably used as a material for forming the solid electrolyte layer.

  By baking in such a temperature range, a solid-phase reaction occurs due to mutual diffusion of the elements constituting each at the interface between the active material molded body 2 and the solid electrolyte layer 3, and an electrochemically inactive byproduct. Can be suppressed. Further, the crystallinity of the inorganic solid electrolyte is improved, and the ionic conductivity of the solid electrolyte layer 3 can be improved. In addition, the adhesion between the active material molded body 2 and the solid electrolyte layer 3 becomes higher, and charge transfer at the interface between the active material molded body 2 and the solid electrolyte layer 3 becomes easy. Thereby, the capacity | capacitance and output of a lithium battery using the electrode assembly 4 are improved.

  The firing may be performed by a single heat treatment, and the first heat treatment for depositing the precursor on the surface of the active material molded body 2 and the temperature condition of the first heat treatment to 700 ° C. or higher. It is good also as performing by dividing into the 2nd heat processing heated by. By performing firing by such stepwise heat treatment, the charge mobility at the interface between the active material molded body 2 and the solid electrolyte layer 3 can be further enhanced.

  As described above, an electrode assembly 4 including the active material molded body 2 and the solid electrolyte layer 3 is obtained.

Then, the manufacturing method of the lithium secondary battery 100 using the electrode assembly 4 is demonstrated.
First, the laminate 10 is formed using the electrode assembly 4. The laminate 10 can be formed by bonding the current collector 1 to the electrode assembly 4. The laminate 10 can be used as a component on one electrode side of the battery.

The electrode composite 4 and the current collector 1 can be joined as follows.
By grinding and polishing one surface 4a of the electrode assembly 4, both the active material molded body 2 and the solid electrolyte layer 3 are exposed from the one surface 4a (see FIG. 5B).

  In addition, in the said process, when the electrode composite 4 is formed, both the active material molded object 2 and the solid electrolyte layer 3 may be exposed from the one surface 4a. In this case, grinding / polishing on the one surface 4a of the electrode assembly 4, that is, this step can be omitted.

  Next, as shown in FIG. 6A, the current collector 1 is joined to the one surface 4a of the electrode assembly 4 (third step). Thereby, the laminated body 10 provided with the active material molded object 2, the solid electrolyte layer 3, and the electrical power collector 1 is formed.

  The current collector 1 may be joined by joining a current collector formed as a separate body to the one surface 4a of the electrode assembly 4, or the current collector 1 described above on the one surface 4a of the electrode composite 4. The current collector 1 may be formed on the one surface 4 a of the electrode assembly 4 by forming the current forming material.

  Moreover, as a film-forming method of the electrical power collector 1, various physical vapor deposition methods (PVD) and chemical vapor deposition methods (CVD) can be used.

Next, the lithium secondary battery 100 is formed using the stacked body 10.
As described above, the laminate 10 is a component that can be used as one electrode of the battery, and the battery is obtained by joining the other electrode component to the other surface 4b of the electrode composite 4 included in the laminate 10. Can be formed. The battery in this embodiment is a lithium secondary battery. The lithium secondary battery 100 is formed through the following steps after the above-described steps.

  As shown in FIG.6 (b), the electrode 20 which is the other electrode structure is joined to the other surface 4b of the electrode composite 4 (4th process).

  The electrode 20 may be joined by joining a separately formed electrode to the other surface 4b of the electrode assembly 4, and the electrode 20 forming material is formed on the other surface 4b of the electrode assembly 4. In addition, the electrode 20 may be formed on the other surface 4 b of the electrode assembly 4.

The electrode 20 can be formed by the same method as described in the method of forming the current collector 1 in the above step.
Through the steps as described above, the lithium secondary battery 100 is manufactured.

(Second Embodiment)
In the present embodiment, a lithium secondary battery having a structure different from that of the first embodiment and a manufacturing method thereof will be described. In the following embodiments including this embodiment, the same number is assigned to the same component as the component in the first embodiment, and the description thereof may be omitted.

FIG. 8 is a longitudinal sectional view of the lithium secondary battery 100A in the present embodiment.
In the lithium secondary battery 100 </ b> A, an electrode composite 4 </ b> A having a configuration different from that of the electrode composite 4 is provided to be joined to the current collector 1 and the electrode 20.

  The volume of the liquid material 3X for forming the solid electrolyte layer 3 may be reduced in the firing process by heating. As a result, the electrode composite 4 has a gap between the active material molded body 2 and the liquid material 3X. There may be new voids of different shapes. The electrode assembly 4A is obtained by filling the new void with the filling layer 30.

The filling layer 30 is formed of a solid electrolyte that conducts lithium ions and is amorphous (glassy or amorphous) at room temperature. The filling layer 30 is formed of, for example, a lithium double oxide containing Si or B having lithium ion conductivity. Specifically, the filling layer 30 may include at least one of Li ₂ SiO ₃ and Li ₆ SiO ₅ .

  Such a packed bed 30 may be formed by, for example, impregnating the above-mentioned new voids with a precursor solution having fluidity, that is, a precursor solution of a solid electrolyte that is amorphous at room temperature, followed by heating. Can be formed.

In addition, as the filling layer 30, it is preferable to use a material that is solid (amorphous) at room temperature and has a volume shrinkage smaller than that of the solid electrolyte layer 3 when the precursor is fired. Moreover, it is preferable that the filling layer 30 can be formed at the same level as or lower than the solid electrolyte layer 3. This is to suppress mutual diffusion between the solid electrolyte layer 3 and the filling layer 30. For example, _Li 0.35 _La 0.55 TiO ₃ as the solid electrolyte layer 3, a case of using the _Li 2 SiO ₃ as the filling layer 30. In this case, the firing temperature at the time of forming the solid electrolyte layer 3 is about 700 ° C., but if the formation temperature at the time of forming the filling layer 30 exceeds 800 ° C., the solid electrolyte layer 3 and the filling layer 30 mutually Diffusion may occur. After satisfying this condition, the precursor of the filling layer 30 may be any one of (A) to (C) as in the precursor of the solid electrolyte layer 3. This is diluted with a solvent (for example, an alcohol compound) to obtain a precursor solution. The precursor solution is impregnated in the new void. The method for impregnating the precursor solution is the same as that described for the solid electrolyte layer 3.

  Moreover, the heating temperature which heats the precursor solution with which said new space | gap was filled is set to 300 to 450 degreeC, for example.

(Third embodiment)
In the present embodiment, a lithium secondary battery having a structure different from that of the first embodiment and the second embodiment and a manufacturing method thereof will be described.

FIG. 9 is a longitudinal sectional view of the lithium secondary battery 100B in the present embodiment.
In the lithium secondary battery 100 </ b> B, an electrode composite 4 </ b> B having a configuration different from that of the electrode composite 4 is provided to be joined to the current collector 1 and the electrode 20.

  That is, in the lithium secondary battery 100B of the third embodiment, the electrode assembly 4B includes the active material molded body 2, the solid electrolyte layer 3, and the electrolytic solution 36 filled in the voids remaining due to the formation of the solid electrolyte layer 3. And an electrolyte-impregnated layer 35 bonded to both of the solid electrolyte layer 3 and the electrode 20. In other words, the electrode assembly 4 </ b> B is provided between the electrode assembly 4 and the electrode 20, and the electrolytic solution 36 provided by filling the voids remaining in the electrode assembly 4 of the first embodiment. The electrolyte solution impregnated layer 35 is further provided.

  In this electrode complex 4B, an electrolyte solution impregnated layer 35 is provided between the electrode complex 4 and the electrode 20, and the electrolyte solution 36 is supplied to the remaining space from the electrolyte solution impregnated layer 35 to fill the electrode complex 4B. Is done. As a result, the contact area between the active material molded body 2 and the solid electrolyte layer 3 is prevented from decreasing in the gap, and the resistance between the active material molded body 2 and the solid electrolyte layer 3 is increased. Thus, it is possible to reliably prevent the ion conductivity between the active material molded body 2 and the solid electrolyte layer 3 from being lowered.

  In general, when the charge / discharge cycle is repeated in the lithium secondary battery, the volume of the active material molded body or the solid electrolyte layer may vary. On the other hand, in the present embodiment, for example, even when the volume shrinks and the voids expand, the electrolytic solution further oozes out from the electrolytic solution impregnated layer 35 and the voids are filled with the electrolytic solution 36. On the other hand, even if the volume is increased and the gap is narrowed, the electrolyte solution 36 in the gap is immersed in the electrolyte-impregnated layer 35. As described above, the gap of the electrode assembly 4B becomes a buffer space that absorbs the volume fluctuation, and leads to securing of a charge conduction path. That is, a high output battery can be obtained.

  Note that since the electrolytic solution 36 (ionic liquid in the electrolytic solution-impregnated layer) is small and non-volatile, there is no problem of liquid leakage and combustion.

  The electrolyte solution impregnated layer 35 is a film that functions as a supply source of a lithium-resistant film and a polymer gel electrolyte. The electrolytic solution impregnated layer 35 is a film impregnated with an electrolytic solution that conducts lithium ions. That is, the electrolytic solution impregnated layer 35 includes a support and a polymer gel electrolyte (electrolytic solution).

  The support is for physically supporting the structure of the electrolyte solution impregnated layer (PEG film) 35. The support preferably does not precipitate impurities, does not react with other materials such as a polymer gel electrolyte, and has high wettability with ionic liquid + Li salt + monomer. If impurities are deposited or a chemical reaction occurs, the characteristics may change. Further, when the wettability is poor, there is a possibility that the polymer cannot be formed uniformly on the support. It is possible to improve the strength by increasing the ratio of the polymer component in the polymer gel electrolyte without using the support, but increasing the ratio of the polymer component causes a decrease in the conductivity of Li, so use the support. Is preferred. As the support, for example, long fiber cellulose or hydrophobic PVDF (polyvinylidene fluoride) is used.

  The polymer gel electrolyte is required to have a property that is chemically stable to Li and can be gelled to hold an electrolytic solution. A normal PEG (polyethylene glycol) film becomes a lithium-resistant reduction layer that suppresses reduction, and battery operation can be confirmed. However, the PEG film cannot be expected to improve ion conductivity, and there is a possibility that a practical output as a battery cannot be obtained. In order to obtain a practical output as a battery, it is necessary to improve the conductivity of Li. Therefore, in this embodiment, a gel polymer electrolyte that does not volatilize the electrolyte is used.

  In such an electrode composite 4B, for example, an electrolyte-impregnated layer 35 is attached to one surface of the composite of the active material molded body 2 and the solid electrolyte layer 3 in which voids remain, whereby the electrolyte-impregnated layer 35 is obtained. The electrolyte solution can be formed using a method of supplying the electrolyte solution to the gap.

  The electrolytic solution impregnated layer 35 is produced, for example, by impregnating a support (base material) with a precursor solution containing an electrolytic solution and a monomer and photopolymerizing the precursor solution. The electrolytic solution includes an ionic liquid and a lithium salt. As the ionic liquid, for example, P13-TFSI (N-methyl-N-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide) is used. As the lithium salt, Li-TFSI (lithium N, N-bis (trifluoromethanesulfonyl) imide) is used. For example, polyethylene glycol diacrylate (TEGDA) is used as the monomer. A polymerization initiator and ethylene carbonate are mixed in the above electrolytic solution to obtain a PGE preparation solution. As the polymerization initiator, for example, a radical photopolymerization initiator (for example, IRGACURE651,2,2-dimethoxy-1,2-diphenylethane-1-one manufactured by BASF) is used. The polymerization initiator is mixed at a mixing ratio of, for example, 6: 1 by weight. Ethylene carbonate is used as a SEI (Solid Electrolyte Interface) forming material. SEI is a coating that inactivates and stabilizes the surface of the Li electrode. SEI is produced by a reductive decomposition reaction of the electrolytic solution, and it has been confirmed that charges are consumed by the decomposition reaction of ethylene carbonate in the first cycle. Ethylene carbonate is mixed at a mixing ratio of 1. The support is impregnated with this PGE preparation solution. As the support, for example, a hydrophobic PVDF membrane filter manufactured by MILLIPORE is used. The support impregnated with the PGE preparation solution is irradiated with light of a predetermined wavelength band (for example, ultraviolet light) to photopolymerize the monomer and polymerize to obtain the electrolyte solution impregnated layer 35. The electrolytic solution contained in the electrolytic solution-impregnated layer 35 is filled in the remaining gap and functions as the electrolytic solution 36.

The electrolyte contained in the electrolyte-impregnated layer 35 has good wettability to the solid electrolyte (Li _0.35 La _0.55 TiO ₃ ), and soaks in the remaining voids along the solid electrolyte layer 3. As a result, the electrolyte solution 36 is filled in the gap.

(Fourth embodiment)
In the present embodiment, a lithium secondary battery having a structure different from those in the first to third embodiments and a method for manufacturing the lithium secondary battery will be described.

  FIG. 10 is a longitudinal sectional view of a lithium secondary battery 100C in the present embodiment. The lithium battery 100 </ b> C includes an electrode composite 4 </ b> C having a configuration different from that of the electrode composite 4 between the current collector 1 and the electrode 20.

  The electrode composite 4 </ b> C includes an active material molded body 2 </ b> C having active material particles 21 and noble metal particles 22, and a solid electrolyte layer 3. The noble metal particles 22 are in the form of particles, and are attached to the surfaces of a plurality of active material particles 21 connected to each other or interposed between the active material particles 21.

  Thereby, the noble metal particles 22 are interposed in the transfer of electrons between the plurality of active material particles 21 and the transfer of lithium ions between the active material particles 21 and the solid electrolyte layer 3, and these can be performed more smoothly. Will be able to. Furthermore, the transfer of electrons between the plurality of active material particles 21 and the transfer of lithium ions between the active material particles 21 and the solid electrolyte layer 3 are stably maintained over a long period of time. Therefore, by applying the electrode assembly 4C having such a configuration to the lithium secondary battery 100C, the lithium secondary battery 100C can stably maintain a high output and a high capacity over a long period of time. The noble metal particles 22 preferably contain a noble metal having a melting point of 1000 ° C. or higher as a forming material (constituent material).

  The noble metal having a melting point of 1000 ° C. or higher is not particularly limited, but gold (Au; melting point 1061 ° C.), platinum (Pt; melting point 1768 ° C.), palladium (Pd; melting point 1554 ° C.), rhodium (Rh; melting point 1964 ° C.) ), Iridium (Ir; melting point 2466 ° C.), ruthenium (Ru; melting point 2334 ° C.), osmium (Os; melting point 3033 ° C.), and these metals can be used alone, or alloys of these metals are used. You may do it. Among these, at least one of platinum and palladium is preferable. These noble metals are relatively inexpensive and easy to handle among the noble metals, and are excellent in lithium ion and electron conductivity. Therefore, by using it as a constituent material of the noble metal particles 22, the transfer of electrons between the plurality of active material particles 21 and the transfer of lithium ions between the active material particles 21 and the solid electrolyte layer 3 are performed more smoothly. And capable of being more stably maintained over a long period of time.

  The noble metal particles 22 preferably have an average particle size of 0.1 μm to 10 μm, and more preferably 0.1 μm to 5 μm. The average particle diameter of the noble metal particles 22 can be measured using the same method as that for measuring the average particle diameter of the active material particles 21.

  Furthermore, the content of the noble metal particles 22 in the active material molded body 2C is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 10% by mass or less.

  By setting the average particle size and content of the noble metal particles 22 within the above ranges, the noble metal particles 22 can be more reliably attached to the surface of the active material particles 21 or between the active material particles 21. It becomes possible to intervene. As a result, the transfer of electrons between the plurality of active material particles 21 and the transfer of lithium ions between the active material particles 21 and the solid electrolyte layer 3 can be performed more smoothly, and over a long period of time. It becomes possible to maintain it stably.

  Such an active material molded body 2C can be manufactured, for example, by adding the noble metal particles 22 together with the active material particles 21 in the above-described method for manufacturing a lithium secondary battery.

As mentioned above, although the manufacturing method of the electrode composite_body | complex of this invention and the manufacturing method of a lithium battery were demonstrated based on embodiment of illustration, this invention is not limited to this. For example, one or two or more arbitrary steps may be added to the method for producing an electrode assembly and the method for producing a lithium battery of the present invention. Moreover, the manufacturing method of the lithium battery of this invention is applicable also to manufacture of a primary battery other than manufacture of the lithium secondary battery demonstrated in the said each embodiment. Moreover, the electrode composite manufactured by the method for manufacturing an electrode composite of the present invention has a configuration in which two or more configurations of the electrode composite manufactured in each embodiment described above are arbitrarily combined. Also good.
Note that the present invention can be widely applied without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Current collector 2 Active material molded object 2C Active material molded object 3 Solid electrolyte layer 3X Liquid material 4 Electrode complex 4A Electrode complex 4B Electrode complex 4C Electrode complex 4a One side 4b Other side 5 Pressure-resistant container 10 Laminate 20 Electrode 21 Active Material Particles 22 Precious Metal Particles 26 Slurry 30 Packing Layer 31 Granule 35 Electrolyte Impregnated Layer 36 Electrolyte 51 Tubular Body 52 Filter 53 Piston 54 Internal Space 55 External Space 100 Lithium Secondary Battery 100A Lithium Secondary Battery 100B Lithium Secondary Secondary battery 100C Lithium secondary battery 511 Opening 512 Opening F Molding die F2 Molding die F21 Bottom F22 Lid F25 Recess

Claims (8)

A first step of forming an active material molded body having voids;
A second step of placing the active material molded body and a liquid material containing a solid electrolyte forming material in a pressure resistant container, and setting the pressure inside the pressure resistant container to be higher than atmospheric pressure;
A method for producing an electrode composite comprising:   The method for producing an electrode assembly according to claim 1, wherein the pressure inside the pressure vessel is changed by changing the volume inside the pressure vessel.   The method for producing an electrode assembly according to claim 1, wherein the pressure vessel includes a filter that allows the liquid material to pass therethrough.   The said filter contains a porous body, The manufacturing method of the electrode composite_body | complex of Claim 3 characterized by the above-mentioned.   The method for manufacturing an electrode structure according to claim 3, wherein the filter includes a ceramic material.   The production of the electrode assembly according to any one of claims 3 to 5, wherein the pressure inside the pressure vessel is changed while the active material molded body and the filter are in contact with each other. Method. The pressure vessel is
A cylindrical body having two openings facing each other along an axis;
The filter provided by closing one of the two openings;
A piston provided by closing the other of the two openings and slidable along the axis;
The method for producing an electrode assembly according to any one of claims 3 to 6, further comprising: A current collector joined to one surface of an electrode composite manufactured by the method for manufacturing an electrode composite according to any one of claims 1 to 7 so as to be in contact with the active material molded body. 3 steps,
A fourth step of providing an electrode composition on the other surface of the electrode composite;
Including
The method of manufacturing a lithium battery, wherein the active material molded body is not exposed on the other surface.

Images