JP2008243735A - Solid electrolyte, its molding method, lithium ion secondary battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte having low resistance, its molding method, a lithium ion secondary battery having low internal resistance using the solid electrolyte, and its manufacturing method. <P>SOLUTION: The lithium ion secondary battery has a positive electrode 10, a negative electrode 20, and the solid electrolyte 30 formed of a solid formed of fusion-bonding particles having a crystal phase interposed between the positive electrode 10 and the negative electrode 20. Preferably, the solid electrolyte 30 has a recess and projection on its surface, and the positive electrode 10 and/or the negative electrode 20 have/has a surface shape matching the recess and projection of the solid electrolyte 30. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid electrolyte and a forming method thereof, a lithium ion secondary battery using the solid electrolyte, and a method of manufacturing the same.

  Currently, the electrolyte of a lithium ion secondary battery that is put into practical use in a mobile phone or a notebook computer is composed of a non-aqueous electrolyte solution or a gel electrolyte in which the polymer polymer is held. Since these non-aqueous electrolytes are flammable and have a problem of high possibility of explosion and ignition, it has been studied to use a solid electrolyte made of an inorganic material as an electrolyte.

In general, the solid electrolyte is supplied in the form of powder or particles. When this powdery solid electrolyte is formed into a sheet, conventionally, the solid electrolyte powder and a material for bonding the powders are mixed to form a sheet (see Patent Document 1).
JP 2001-126758 A

  However, in this case, the molded solid electrolyte contains a material that does not contribute to electric conduction, and there is a problem that the internal resistance of the solid electrolyte increases and the ionic conductivity decreases. On the other hand, the solid electrolyte as an aggregate of powder that does not contain an adhesive material has a problem that the resistance inside the solid electrolyte similarly increases due to the contact resistance between the powders.

  An object of the present invention is to provide a solid electrolyte having a low resistance and a molding method thereof, a lithium ion secondary battery having a low internal resistance using the solid electrolyte, and a method for producing the same.

  In order to solve the above-mentioned problems, the solid electrolyte according to the present invention is characterized in that particles having a crystalline phase are fused and formed.

  According to such a configuration, since the particles having a crystal phase are fused, the contact resistance is lower than when the particles are simply in contact with each other. Moreover, since one molded solid electrolyte is comprised even if it does not contain materials, such as a binder which does not contribute to electrical conduction, resistance can be made low compared with such a case.

  In order to solve the above problems, a lithium ion secondary battery according to the present invention includes a positive electrode, a negative electrode, and a solid electrolyte formed by fusing particles having a crystalline phase interposed between the positive electrode and the negative electrode. And including.

  According to such a configuration, since the particles having a crystal phase are fused, the contact resistance is lower than when the particles are simply in contact with each other. Therefore, the resistance of the solid electrolyte can be lowered. Even if a material such as a binder that does not contribute to electrical conduction is not included, one molded solid electrolyte is formed, so that the resistance can be lowered as compared with such a case. Since the resistance of the solid electrolyte can be lowered, the internal resistance of the battery is reduced.

  The solid electrolyte preferably has irregularities formed on the surface thereof, and the positive electrode and / or the negative electrode preferably have a surface shape that matches the irregularities of the solid electrolyte. The power density of the battery is also related to the contact area between the electrode and the solid electrolyte. For this reason, the output density of a battery can be raised with the said structure.

  More preferably, the positive electrode and / or the negative electrode include a sheet-like current collector and an active material layer including active material particles provided on the solid electrolyte side of the current collector. When the active material layer disposed on the solid electrolyte side of the current collector contains particles of the active material, the particles are filled in the irregularities on the surface of the solid electrolyte, and as a result, the surface shape of the active material layer is solid. It matches the unevenness of the electrolyte surface. In the above configuration, the patterning step is not required in order to obtain the surface shape of the active material layer that matches the surface shape of the solid electrolyte.

  The active material layer preferably includes the active material particles and the solid electrolyte particles, and the active material and the solid electrolyte particles are preferably fused. Thus, the contact area between the active material and the solid electrolyte particles can be increased as compared with the case where the active material and the solid electrolyte particles are in contact only at the interface between the active material layer and the solid electrolyte. Moreover, the contact resistance between different particles can be kept low by fusing the active material and the solid electrolyte particles.

  In order to solve the above problems, a method for forming a solid electrolyte according to the present invention includes pressing a solid electrolyte powder in a heated state to fuse particles in the powder to form a solid electrolyte. It is characterized by.

  According to such a configuration, the particle surface layer is bonded (fused) in a slightly melted state, and a solid electrolyte molded product is obtained. Accordingly, a solid electrolyte molded product can be obtained from the solid electrolyte powder without using an adhesive that does not contribute to electrical conduction.

  In order to solve the above-described problems, a method for manufacturing a lithium ion secondary battery according to the present invention includes pressing a solid electrolyte powder in a heated state to fuse particles in the powder to obtain a solid electrolyte. A step of forming, and a step of thermocompression bonding the positive electrode and the negative electrode on both sides of the solid electrolyte.

  According to such a configuration, the surface layer of the particles is joined (fused) in a slightly melted state to obtain a solid electrolyte molded product, and the positive electrode and the negative electrode are thermocompression bonded to both sides of the solid electrolyte. A lithium ion secondary battery is manufactured. Therefore, a molded product of the solid electrolyte can be manufactured from the powder of the solid electrolyte without using an adhesive that does not contribute to electrical conduction, and a lithium ion secondary battery is manufactured using the solid electrolyte.

  In the step of forming the solid electrolyte, the solid electrolyte powder is preferably pressed in a state of being heated to a temperature not lower than the transition temperature of the solid electrolyte and not higher than the softening temperature. By heating above the transition temperature of the solid electrolyte, the particles in the powder can be crystallized and fused. In addition, if the heating exceeds the softening point temperature, the crystal structure may change and the electrical conductivity may decrease, so it is preferable to heat to a temperature below the softening point temperature.

  In the step of forming the solid electrolyte, the solid electrolyte powder is pressed in a heated state under reduced pressure. Thereby, the space | gap between solid electrolyte particles can be reduced, and a denser fusion | fusion is attained. Dense fusion leads to an increase in the contact area of the solid electrolyte particles, and can reduce the resistance of the solid electrolyte.

  According to the solid electrolyte of the present invention, the resistance of the solid electrolyte can be lowered. Moreover, according to the lithium ion secondary battery of this invention, the internal resistance of a battery can be made low by making resistance of a solid electrolyte low. Further, according to the method for molding a solid electrolyte of the present invention, a solid electrolyte having low resistance can be easily molded without using an adhesive. Furthermore, according to the manufacturing method of the lithium ion secondary battery of this invention, a lithium ion secondary battery with low internal resistance can be manufactured.

  Embodiments of the present invention will be described below with reference to the drawings.

<Configuration of lithium ion secondary battery>
FIG. 1 is a schematic cross-sectional view of a lithium ion secondary battery according to this embodiment. The lithium ion secondary battery includes a positive electrode 10, a negative electrode 20, and an electrolyte 30 interposed between the positive electrode 10 and the negative electrode 20.

  The positive electrode 10 includes a sheet-like positive electrode current collector 11 and a positive electrode active material layer 12 disposed on the solid electrolyte 30 side of the positive electrode current collector 11.

  The positive electrode current collector 11 is disposed for collecting the positive electrode 10 and is made of a metal or an alloy such as aluminum, titanium, or stainless steel. In order to promote the retention of the active material, the surface of the current collector can be roughened, roughened, or provided with a large number of minute holes (50 μm or less).

The positive electrode active material layer 12 includes positive electrode active material particles made of a metal oxide containing lithium capable of electrochemically inserting or removing lithium by an oxidation-reduction reaction. The metal oxide containing such a lithium, lithium-cobalt composite oxide such as LiCoO _2, lithium-nickel composite oxide such as LiNiO _2, lithium-manganese-based composite oxide such as LiMn ₂ O _4, Lithium / vanadium complex oxides such as V ₂ O ₅ and lithium / iron complex oxides such as LiFeO ₂ can be used.

  In addition to the positive electrode active material particles, the positive electrode active material layer 12 may include a binder for solidifying the positive electrode active material particles and a conductive agent for enhancing electrical conduction. As the binder, rubber resins such as styrene-butadiene rubber (SBR), fluorine resins such as polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), N · methyl · 2 pyrrolidone (NMP), etc. It can be suspended in an aqueous solution or solvent. However, since the binder does not contribute to electrical conduction, it is preferable not to use it as much as possible. As the conductive agent, a carbon-based material such as acetylene black, graphite, or carbon nanotube can be used.

  The negative electrode 20 includes a sheet-like negative electrode current collector 21 and a negative electrode active material layer 22 disposed on the solid electrolyte 30 side of the negative electrode current collector 21. In order to promote the retention of the active material, the surface of the current collector can be roughened, roughened, or provided with a large number of minute holes (50 μm or less).

  The negative electrode current collector 21 is disposed for collecting current of the negative electrode 20, and a metal or an alloy such as copper, aluminum, nickel, titanium, or stainless steel can be used. Moreover, in order to promote retention of the active material, the surface of the current collector can be provided with irregularities, roughened surface, or a large number of fine holes (50 μm or less).

  The negative electrode active material layer 22 includes negative electrode active material particles capable of electrochemically inserting or removing lithium by an oxidation-reduction reaction. Examples of such negative electrode active material particles include metallic lithium and LiAl, LiAg, LiPb, and LiSi alloys that are alloyed with lithium. Also, general carbon materials such as graphite, non-graphitizable carbon obtained by firing carbonized resin, graphitizable carbon obtained by heat treating coke, and fullerene can be used.

  In addition to the negative electrode active material particles, the negative electrode active material layer 22 may include a binder for solidifying the negative electrode active material particles and a conductive agent for enhancing electrical conduction. However, since the binder does not contribute to electrical conduction, it is preferable not to use it as much as possible. The types of the binder and the conductive agent are the same as those described for the positive electrode active material layer 12.

The material of the solid electrolyte 30 is preferably a flame retardant glass ceramic material, such as lithium phosphate such as LiPON, or lithium sulfide such as Li ₂ S—P ₂ S ₅ or thio-LISICON. A composite oxide system such as LiNbO ₃ and LiTaO ₃ can be used. In particular, Li ₂ S—P ₂ S ₅ shows the same conductivity even if it is repeatedly heat-treated in the temperature range of 240 ° C. to 360 ° C. for many hours, so heat treatment processes such as heat fusion molding and heat fusion pressure bonding It is preferable in the process of performing several times.

  FIG. 2 is a diagram illustrating an example of a detailed configuration of the lithium ion secondary battery 1 according to the present embodiment. FIG. 3 is a cross-sectional view showing a preferred embodiment of the solid electrolyte 30.

  As shown in FIG. 2, the solid electrolyte 30 according to the present embodiment is formed by fusing and molding solid electrolyte particles 31 having a crystal phase and having a particle diameter of around several tens of microns. The average particle size of the solid electrolyte particles 31 is preferably 5 μm to 50 μm, more preferably about 10 μm to about 20 μm. Here, it is not preferable that the average particle diameter is less than 5 μm, since the particles easily aggregate. When the average particle size is larger than 50 μm, the contact area between the fine particles becomes small, and voids are contained inside the molded body, which is not preferable.

  As shown in FIG. 3, it is preferable that irregularities are formed on the surface of the solid electrolyte 30. The active material layers 12 and 22 of the positive electrode 10 and / or the negative electrode 20 that are in contact with the solid electrolyte surface have an uneven shape according to the uneven shape. In this case, the unevenness on the surface of the solid electrolyte may be formed only on one side or on both sides. However, when a metal is used for the positive electrode and / or the negative electrode active material, it is natural that the pole side is preferably flat. With regard to the uneven shape, various shapes such as a cylinder, a cone, a quadrangular column, a quadrangular pyramid, a wave shape, and a linear shape are conceivable, and combinations thereof may be used. It is preferable that the uneven shape is formed on almost the entire surface of the solid electrolyte.

  The aspect ratio (b / a) of the unevenness of the solid electrolyte 30 is preferably 2 or more, more preferably 5 or more. As the aspect ratio of the irregularities on the surface of the solid electrolyte 30 increases, the contact area between the solid electrolyte 30 and the electrode increases accordingly, so that the output density can be improved.

  In addition, as shown in FIG. 2, in the present embodiment, the positive electrode active material layer 12 includes the positive electrode active material particles 13 and the same solid electrolyte particles 14 as the particles constituting the solid electrolyte 30, It is preferable that the solid electrolyte particles 14 are fused. The negative electrode active material layer 22 includes the same solid electrolyte particles 24 as the particles constituting the negative electrode active material particles 23 and the solid electrolyte 30, and the negative electrode active material particles 23 and the solid electrolyte particles 24 are fused. preferable. Note that the solid electrolyte particles dispersed in the active material particles themselves are ionic conductors, and therefore do not increase the resistance of the positive electrode active material layer 12. In addition, a binder need not be added to the active material layers 12 and 22, but a conductive agent may be added as necessary.

  The effects of the solid electrolyte according to the present embodiment and the lithium ion secondary battery 1 using the solid electrolyte will be described.

  Since the solid electrolyte 30 according to the present embodiment is made of a solid in which particles having a crystal phase are fused, the contact resistance can be remarkably reduced as compared with a state where the particles are simply in contact with each other. In addition, since the solid electrolyte 30 does not include a material (component) such as a binder that does not contribute to electrical conduction, the resistance can be lowered as compared with such a case.

  Further, by making the surface of the solid electrolyte 30 uneven, and disposing the positive electrode and the negative electrode that match the surface shape of the solid electrolyte 30, the surface area of the electrode is increased compared to the case where the surface of the solid electrolyte 30 is flat. can do. Therefore, the capacity of the lithium ion secondary battery can be increased. In this case, the unevenness on the surface of the solid electrolyte may be one side or both sides.

  Further, since the positive electrode active material layer 12 includes the positive electrode active material particles 13 and the solid electrolyte particles 14 and the positive electrode active material particles 13 and the solid electrolyte particles 14 are fused, the different types of particles simply come into contact with each other. The contact resistance can be remarkably reduced as compared with the existing state. The same applies to the negative electrode active material layer 22.

  By forming the positive electrode active material layer 12 and / or the negative electrode active material layer 22 from an aggregate of particles, it is easy to form a three-dimensional shape that matches the surface shape of the solid electrolyte 30 without using a technique such as lithography or etching. Become. Therefore, the surface area of the electrode can be easily increased, and a high capacity can be realized.

  Further, the solid electrolyte particles in the positive electrode active material layer 12 and / or the negative electrode active material layer 22 are fused to the particles in the solid electrolyte 30, so that the solid electrolyte 30 and the active material layers 12 and 22 are bonded. They can be integrated, and the interface resistance between them can be reduced.

  Next, a method for forming the solid electrolyte 30 and a method for manufacturing the lithium ion secondary battery 1 according to the present embodiment will be described.

<Solid electrolyte production method>
4 to 6 show an outline of a jig configuration for forming a solid electrolyte. In order to produce a solid electrolyte having irregularities and a positive electrode and / or a negative electrode, the solid electrolyte is first molded. A pressure jig is used for molding. For example, as shown in FIG. 4, a hollow ring 40 having a sufficiently high strength and thickness is prepared. Further, as shown in FIG. 5, two cylinders 41 having a diameter that can be inserted into the ring inner diameter without any gap are prepared. A predetermined concavo-convex shape 42 is formed on one side of the cylinder 41, and the other end is processed into a flat 43. Further, as shown in FIG. 6, two cylinders 49 having a diameter that can be inserted into the inner diameter of the hollow ring 40 without a gap and flat on both sides are prepared.

  As shown in FIG. 7, first, one column 41 is placed on the holding jig 44a with the concavo-convex shape 42 facing up. Then, the hollow ring 40 is inserted into the cylinder 41. At this time, the height of the cylinder 41 is adjusted by a holding jig so as not to jump out of the hollow ring 40.

  Next, as shown in FIG. 8, an appropriate amount of solid electrolyte powder 45 made of fine powder is put into the hollow ring 40. This amount determines the thickness of the solid electrolyte after pressure fusion molding. If the amount is too small, holes are formed due to the formed irregularities, and if the amount is too large, the resistance value becomes high. Therefore, it is preferable to add an amount that gives a thickness (average) of about 50 μm to about 500 μm after molding. After the solid electrolyte powder 45 is added, vibration or the like may be applied to the holding jig 44a so that the particles have a uniform thickness on the uneven shape 42.

  Next, as shown in FIG. 9, the remaining cylinder 41 is inserted into the hollow ring 40 so that the concave / convex shape 42 faces downward. At this time, the flat portion 43 of the cylinder 41 protrudes from the hollow ring 40.

  Next, as shown in FIG. 10, the holding jig 44b is placed on the holding jig 44a. The holding jig 44b is preferably provided with a decompression port 46 for decompressing the inside of the hollow ring 40.

  Next, as shown in FIG. 11, a spring 47 that absorbs an impact during pressurization is placed on the holding jig 44 b, and the pressurizing pin 48 presses the flat part 43 of the column 41 to the holding jig 44 b. insert.

  As the jig used for the heat fusion molding, a material which is not deformed by heating or pressurization and has a small expansion is selected. In particular, since the hollow ring 40 and the two cylinders 41 are important parts involved in molding, Fe-Ni-Mo alloys such as Hastelloy and N-155, Fe-Ni-Cr-Co alloys, graphite, quartz, etc. It is preferable to use a material having a small coefficient of thermal expansion and high heat resistance and strength.

  After preparing for pressurization in this way, pressurization is performed. For pressurization, a general press apparatus such as a hydraulic press can be used in accordance with the shape of the pressurizing jig. Although the pressurization may be in the vertical direction or the horizontal direction, in order to keep the solid electrolyte particles uniformly between the cylinders 41, it is preferable to press in the vertical direction.

Here, if the pressure of the pressurization is small, the fusion is incomplete and the unevenness cannot be formed well. On the other hand, since the solid electrolyte is destroyed when the pressure becomes 10 t / cm ² or more, the pressure is at least 2000 kg / cm ² , and it is preferable to change this pressure depending on the amount of the solid electrolyte particles introduced. In addition, by reducing the pressure inside the hollow ring 40 from the pressure reducing port 46 to the atmospheric pressure or lower during pressurization, voids between the solid electrolyte particles can be eliminated, and a denser fusion can be achieved.

  Although the pressurization time at the time of holding the target heating temperature depends on the holding temperature and the amount of the solid electrolyte powder, it cannot be generally specified, but is preferably several hours or less. Further, it is preferable that the pressurization is continued in all the steps of raising temperature, maintaining temperature, and decreasing temperature.

  Since the heating may be performed so long as the portion where the solid electrolyte is formed reaches a predetermined temperature, for example, only the portion containing the solid electrolyte particles may be heated, or the entire heating jig may be heated.

  A normal heating method can be used for heating. For example, resistance heating, high frequency heating, or the like can be used. At this time, temperature control is performed by a temperature controller or the like so that the temperature of the portion where the solid electrolyte is formed becomes relatively uniform. The heating temperature is preferably a temperature not lower than the transition point temperature and not higher than the softening point temperature of the solid electrolyte material. More preferably, it is not lower than the transition temperature and not higher than the transition temperature + 200 ° C. If the heating temperature exceeds the softening point temperature, the crystal structure may change and the conductivity may decrease, and the softened solid electrolyte may be firmly attached to the pressure jig, which is preferable. Absent.

  By the heating, the particles in the solid electrolyte powder 45 are crystallized. And, together with the effect of pressurization, particles having a crystal phase are fused together to form a desired molded product. It is not necessary to simultaneously crystallize and fuse the particles, and heat treatment for crystallizing the solid electrolyte powder 45 may be performed before heat fusion molding. The heat treatment temperature at this time is the same as that in the heat fusion molding described above.

  After producing the three-dimensional solid electrolyte molded product 50 by heat fusion molding, the electrodes are crimped. In this case as well, a pressurizing jig is used, but unlike the case of the solid electrolyte, two cylinders 49 in which both ends of the cylinder 41 are flat are used. The column 49 is set up on the holding jig 44a, and the hollow ring 40 is inserted into the column. Then, a metal foil to be the negative electrode current collector 21 cut out to a diameter slightly smaller than the inner diameter of the hollow ring is placed on the cylinder 49, and further, the solid electrolyte particles 24 are added and dispersed in the negative electrode active material particles 23 thereon. (Hereinafter, negative electrode agent) is introduced so as to have a uniform thickness. At this time, vibration may be applied to the holding jig 44a.

  Next, a molded product of the solid electrolyte 30 formed by heat fusion molding is placed on the negative electrode agent, and a solid electrolyte particle 14 added and dispersed on the positive electrode active material particles 13 thereon (hereinafter, positive electrode agent) is used as the electrolyte agent. Put evenly on the surface. At this time, vibration may be applied to the holding jig 44a again. Then, a metal foil serving as a positive electrode current collector cut out to a diameter slightly smaller than the inner diameter of the hollow ring is placed on the positive electrode agent, and another cylinder 49 is inserted into the hollow ring 40.

  In this way, the negative electrode current collector-negative electrode agent-solid electrolyte-positive electrode agent-positive electrode current collector is laminated, and after preparation for pressurization is completed, heat fusion is performed in the same manner as the heat fusion molding of the solid electrolyte. The lithium ion secondary battery 1 having a three-dimensional electrode is manufactured by performing pressure bonding. In this case as well, the pressurization may be in either the vertical direction or the horizontal direction, but since a large number of materials are laminated, it is preferable to apply pressure in the vertical direction. In this example, the negative electrode current collector is laminated, but the positive electrode current collector may be laminated. By laminating in this way, the battery cell structure can be formed by one-time heat fusion bonding, which is effective for cost reduction. Further, in this example, the negative electrode current collector-negative electrode agent (hereinafter referred to as negative electrode) and the positive electrode current collector-positive electrode agent (hereinafter referred to as positive electrode) were simultaneously heat-sealed and bonded, but the negative electrode formed by a coating method or the like in advance. Alternatively, a positive electrode, a negative electrode, an electrolyte agent, and a positive electrode can be laminated and heat-sealed.

Since a large number of materials are laminated in the heat fusion pressure bonding, since a laminated structure is not formed if the pressure at the time of pressurization is low, it is preferable to pressurize at a pressure of at least 1000 kg / cm ² . This pressure is preferably changed according to the height of the laminated structure, that is, the negative electrode agent input amount, the thickness of the solid electrolyte, and the positive electrode agent input amount. In addition, when a high pressure is applied at a stretch, the laminated structure may be broken, so it is preferable to increase the pressure gradually.

  On the other hand, the heating temperature is preferably the same as the temperature at which the solid electrolyte is heat-sealed or formed, or higher by several tens of degrees Celsius. When the heat fusion pressure bonding temperature is too high, although stronger fusion is possible, fusion to the pressure jig is also not preferable.

  Here, it is shown that the solid electrolyte having a crystalline phase is formed by heat fusion molding. However, the solid electrolyte is heated simultaneously with the crystallization of the glassy solid electrolyte also as a heat treatment for precipitating the crystalline phase on the glassy solid electrolyte particles. Fusion molding may be performed.

[Example 1]
First, one side was flat, and two cylinders 41 with a diameter of 20 mm were prepared on the remaining one side, with linear traces having a depth of 200 μm, a line width of 100 μm, and a vertical and horizontal pitch of 200 μm. The hollow ring 40 was inserted with the cylinder standing on the holding jig with the line traces facing up.

Next, Li ₂ S—P ₂ S ₅ , which is a lithium sulfide-based crystal, was prepared as the solid electrolyte powder 45. Li ₂ S—P ₂ S ₅ was prepared as follows. Weighing so that Li ₂ S: P ₂ S ₅ = 70: 30 (molar ratio), mixing in a mortar, and treatment for 20 hours at room temperature in a nitrogen atmosphere by mechanical milling using a planetary ball mill To obtain glassy Li ₂ S—P ₂ S ₅ . Thereafter, this glassy Li ₂ S—P ₂ S ₅ was heat-treated at 300 ° C. to obtain a solid electrolyte Li ₂ S—P ₂ S ₅ having a crystalline phase. The Tg of this solid electrolyte was about 210 ° C. The average particle size was 21 μm.

100 mg of this solid electrolyte powder was placed on the linear trace so that the height was uniform. Then, the other cylindrical column 41 is inserted into the hollow ring 40 with the linear mark down, and the holding jig 44b is placed on them, and the spring 47 and the pressure pin 48 are placed in a fixed position before pressing. It was a product. This pre-pressurized product was set in a hydraulic press machine, the pressure inside the pre-pressurized product was reduced to 10 Pa, and the pre-pressurized product was heated at 330 ° C. for 1 hour while applying a pressure of 3800 kg / cm ² . Thereafter, the temperature was lowered while continuing the pressurization to obtain a solid electrolyte molded product heat-sealed to a diameter of 20 mm and a thickness of 500 μm. A linear shape having a depth of about 180 μm was transferred to the front and back surfaces of the solid electrolyte.

On the other hand, LiCoO ₂ is prepared as the positive electrode active material particles 13 and graphite is prepared as the negative electrode active material particles 23, and the positive electrode is LiCoO ₂ : acetylene black: solid electrolyte = 5: 1: 4 (wt%). In this ratio, a negative electrode and a negative electrode were prepared by uniformly mixing them in a ratio of graphite: solid electrolyte = 5: 5 (wt%). Moreover, as the positive electrode current collector 11 and the negative electrode current collector 21, an aluminum foil and a copper foil each having a diameter of 20 mm were prepared. Further, two cylinders 49 having flat ends are prepared.

  Next, the hollow ring 40 was inserted with the cylinder 49 standing on the holding jig 44a. Then, the copper foil is placed on a cylinder, and thereafter, the negative electrode agent, the solid electrolyte, the positive electrode agent, and the aluminum foil are laminated in this order. Finally, the cylinder 49 is inserted into the hollow ring, the holding jig 44b, the spring 47, and the pressurization. The pin 48 was placed at a fixed position to obtain a pre-crimped product.

This pre-compression product was set in a hydraulic press, the pre-compression product was depressurized to 10 Pa, and the pre-compression product was heated at 360 ° C. for 1 hour while applying a pressure of 2800 kg / cm ² . Thereafter, the temperature was lowered while continuing the pressurization to obtain a battery which was heat-sealed and bonded to an outer diameter of 20 mm and a thickness of 900 μm. When the electric conductivity of this battery was measured using the alternating current impedance method, it was 3.2 × 10 ⁻³ S / cm. When the capacity was further examined, it was 203 mAh / g.

[Example 2]
When producing the solid electrolyte of Example 1, a battery was fabricated in the same manner as in Example 1 except that a cylinder in which both ends were flat on the surface in contact with the negative electrode side and indium foil was used as the negative electrode agent. Produced. In this case, the positive electrode side of the solid electrolyte agent of the battery is uneven, and the negative electrode side is flat. The conductivity of this battery was measured using an AC impedance method and found to be 2.9 × 10 ⁻³ S / cm. When the capacity was examined, it was 135 mAh / g.

[Example 3]
When producing the solid electrolyte of Example 1, a battery was produced in the same manner as in Example 1 except that two cylinders having flat ends were used. In this case, the surface of the solid electrolyte of the battery is flat with no irregularities. The conductivity of this battery was measured using an AC impedance method and found to be 2.3 × 10 ⁻³ S / cm. When the capacity was examined, it was 88 mAh / g.

[Comparative Example 1]
In the case of producing the solid electrolyte of Example 1, the same method as in Example 1 was used except that two cylinders with flat ends were used and the solid electrolyte was molded by applying pressure without heating. A battery was produced. In this case, the surface of the solid electrolyte of the battery is flat with no irregularities. The conductivity of this battery was measured using an AC impedance method and found to be 8.3 × 10 ⁻⁴ S / cm. When the capacity was examined, it was 59 mAh / g.

The present invention is not limited to the description of the above embodiment.
In addition, various modifications can be made without departing from the scope of the present invention.

It is a schematic sectional drawing of the lithium ion secondary battery which concerns on this embodiment. It is sectional drawing which shows the detailed structure of a lithium ion secondary battery. It is a figure which shows the structure of a solid electrolyte. It is a figure which shows the jig | tool used for shaping | molding of a solid electrolyte. It is a figure which shows the jig | tool used for shaping | molding of a solid electrolyte. It is a figure which shows the jig | tool used for shaping | molding of a solid electrolyte. It is a figure for demonstrating the shaping | molding method of a solid electrolyte. It is a figure for demonstrating the shaping | molding method of a solid electrolyte. It is a figure for demonstrating the shaping | molding method of a solid electrolyte. It is a figure for demonstrating the shaping | molding method of a solid electrolyte. It is a figure for demonstrating the shaping | molding method of a solid electrolyte.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lithium ion secondary battery, 10 ... Positive electrode, 11 ... Positive electrode collector, 12 ... Positive electrode active material layer, 13 ... Positive electrode active material particle, 14 ... Solid electrolyte particle, 20 ... Negative electrode, 21 ... Negative electrode collector 22 ... Negative electrode active material layer, 23 ... Negative electrode active material particle, 24 ... Solid electrolyte particle, 30 ... Solid electrolyte, 31 ... Solid electrolyte particle, 40 ... Hollow ring, 41 ... Cylinder, 42 ... Uneven portion, 43 ... Flat portion, 44a, 44b ... holding jig, 45 ... solid electrolyte powder, 46 ... decompression port, 47 ... spring, 48 ... pressure pin, 49 ... cylinder

Claims (9)

The particles having a crystalline phase are fused and shaped,
Solid electrolyte. A positive electrode;
A negative electrode,
A solid electrolyte formed by fusing particles having a crystalline phase interposed between the positive electrode and the negative electrode;
Lithium ion secondary battery containing. The solid electrolyte has irregularities formed on the surface,
The positive electrode and / or the negative electrode has a surface shape that matches the irregularities of the solid electrolyte,
The lithium ion secondary battery according to claim 2. The positive electrode and / or the negative electrode is
A sheet-like current collector;
An active material layer including active material particles provided on the solid electrolyte side of the current collector;
The lithium secondary battery according to claim 3, comprising: The active material layer is
Particles of the active material;
The solid electrolyte particles,
The active material and the solid electrolyte particles are fused.
The lithium ion secondary battery according to claim 4. By pressing the solid electrolyte powder in a heated state, the particles in the powder are fused to form a solid electrolyte.
A method for forming a solid electrolyte. Pressing the solid electrolyte powder in a heated state to fuse the particles in the powder to form a solid electrolyte; and
Heat-pressing a positive electrode and a negative electrode on both sides of the solid electrolyte;
The manufacturing method of the lithium ion secondary battery which has this. In the step of forming the solid electrolyte, the powder of the solid electrolyte is pressed at a temperature equal to or higher than the transition temperature of the solid electrolyte and heated to a temperature equal to or lower than the softening temperature.
The manufacturing method of the lithium ion secondary battery of Claim 7. In the step of forming the solid electrolyte, pressing the solid electrolyte powder in a heated state under reduced pressure,
The manufacturing method of the lithium ion secondary battery of Claim 7.

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