JP2009158476A - Sulfide-based lithium-ion-conducting solid electrolyte glass, all-solid lithium secondary battery, and method of manufacturing all-solid lithium secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily inexpensively manufacture an all-solid lithium secondary battery having high charge discharge output current density. <P>SOLUTION: The method of manufacturing the all-solid lithium secondary battery is that a mixed electrolyte formed by mixing various sulfide-based lithium ion conductive solid electrolytes with α-alumina is vitrified to form a new lithium ion conductor having improved conductivity. An electrolyte layer 8 using the lithium ion conductor, a positive electrode (I) comprising a positive mix material 3, and a negative electrode (II) comprising negative mix material 7 are composed. At least one of the positive electrode (I) and the negatived electrode (II) and the electrolyte layer 8 are stacked, heated and compressed under conditions in which the electrolyte is not crystallized to integrate them and manufacture the battery. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sulfide-based lithium ion conductive solid electrolyte glass, an all-solid lithium secondary battery, and a method for producing an all-solid lithium secondary battery.

In recent years, with the development of portable devices such as personal computers and mobile phones, the demand for small and lightweight secondary batteries as the power source has become very large. Among the secondary batteries, in particular, the lithium secondary battery has a high energy density because the atomic weight of lithium is small and the ionization energy is large. Therefore, research on such a battery has been actively conducted, and at present, it is used for a wide range of applications such as a power source of a portable device.
Depending on the type of electrolyte, such lithium secondary batteries include a lithium ion battery using a liquid electrolyte, a lithium ion polymer battery using a polymer solid electrolyte, or a lithium ion battery using an inorganic lithium ion conductive solid electrolyte. Etc. can be broadly classified.

Among these, the all-solid lithium secondary battery has a structure as shown in FIG. That is, the positive electrode (I) is inserted into the insulating cylindrical tube 104 made of polypropylene resin, and the positive electrode (I) is formed by adding about 4 tons of a positive electrode mixture 103 made of a positive electrode active material and a solid electrolyte powder by a mold. In this case, the positive electrode current collector 102 that is pressure-molded with a pressure of / cm ² and electrically connected to the positive electrode lead plate 101 is inserted into the positive electrode (I).
The negative electrode (II) is prepared by preparing a negative electrode mixture 107 made of a negative electrode active material and an electrolyte powder, inserting a negative electrode current collector 106, and press-molding it. The lithium ion conductive solid electrolyte layer 108 is interposed between the positive electrode (I) and the negative electrode (II), and the whole is press-pressed to integrate the positive electrode layer, the electrolyte layer, and the negative electrode layer. Thus, an all solid lithium secondary battery element is produced.

Among them, the lithium ion conductive solid electrolyte layer 108 is mixed with α-alumina (Al ₂ O ₃ ) in the sulfide-based lithium ion conductive solid electrolyte, so that the sulfide-based lithium ion conductive solid as a base material is mixed. A material that improves the ionic conductivity of the electrolyte is used. In an all-solid lithium secondary battery using such an electrolyte layer, it is known that the charge / discharge output characteristics of the produced all-solid lithium secondary battery are improved.
In these battery elements, a positive electrode (I) and a negative electrode (II) are press-molded molds that also serve as respective electrode terminals. I) It is created by tightening firmly using bolts and nuts interposing an insulating rod for preventing a short circuit of the negative electrode (II). In addition, these manufacturing processes are processed in a room temperature region in a dry inert gas atmosphere.

The sulfide-based lithium ion conductive solid electrolyte layer 108 used here is mainly a sulfide-based lithium ion conductive solid electrolyte, and these electrolytes are crystalline or amorphous. ing. A battery made using such a material is in a state where the entire battery is pressed and compressed in the insulating cylindrical tube 104 and is firmly solidified, and as a result, occurs during the battery charge / discharge cycle. It is possible to avoid the inhibition of bonding at the contact interface between the electrode active material and the electrolyte powder, which is caused by the volume expansion and contraction of the electrode active material.
Therefore, a decrease in the battery discharge capacity accompanying the charge / discharge cycle is prevented, and the battery exhibits excellent characteristics. Here, assuming a shape of a practical battery that is not tightly surrounded by the insulating cylindrical tube 104, the battery discharge capacity is greatly reduced with the charge / discharge cycle cycle.

  Further, as another all-solid lithium secondary battery, as shown in Non-Patent Document 1 below, an all-solid thin film configured by sequentially forming a positive electrode thin film, an electrolyte thin film, and a negative electrode thin film using a vapor deposition apparatus or a sputtering apparatus. A lithium secondary battery is disclosed, and it has been reported that excellent charge / discharge cycle characteristics of several thousand cycles or more can be obtained. In this battery, the inside of the electrolyte layer formed by vapor deposition is made of a single thin electrolyte plate without grain boundaries, so the movement of lithium ions, which are mobile ions, in the electrolyte is affected by the joint grain boundaries of the electrolyte particles. In this case, the intergranular bonding is hardly inhibited against the volume expansion / contraction caused by the charging / discharging of the electrode active material, so that the charge / discharge cycle life is excellent.

S. D. Jones and J.M. R. Akridge, J .; Power Sources, 43-44, 505 (1993)

  However, in the above-described all solid lithium secondary battery, in the electrolyte layer and the electrode layer, the solid electrolyte is simply formed by compressing the electrolyte powder particles by pressure compression, and the contact interface is in a state where grain boundaries exist. Therefore, the bonding force is weak. In particular, when an all-solid lithium secondary battery is charged at a high rate, due to the difference in current density distribution inside the battery that occurs at that time, the electrode volume change is extremely large in the portion where the current density distribution is strong, and the electrode active material and the electrolyte Electronic bonding inhibition occurs at the particle bonding interface.

  At this time, in a battery system using a reversible precipitation reaction of lithium metal as a reaction of the negative electrode active material, lithium ions are converted into a tree-like lithium metal at the junction grain boundary between the electrolyte powder particles in the electrolyte layer. To precipitate. As a result, in such an all-solid lithium secondary battery, the charge / discharge output current density is lowered with the charge / discharge cycle, and the capacity is also lowered for a while. In addition, the deposited lithium-like lithium metal has various problems such as causing an electrical short circuit between the positive electrode and the negative electrode by spreading the interface between the electrolyte particles and precipitating between them.

  In addition, in order to make an all-solid-state thin film lithium secondary battery a practical battery, it is necessary to use a high-capacity battery. For this purpose, it is used while maintaining the ion conduction path in the electrode layer. It is necessary to increase the amount of electrode active material to be used. When this technique is used and the electrode layer is thickened as it is, the electrode resistance increases. In order to lower such resistance, it is necessary to deposit an ion conductive electrolyte material between electrode active materials at the time of electrode deposition. Not only the deposition time is increased, but the deposition apparatus is an expensive apparatus such as a multi-source evaporation apparatus. And the manufacturing cost of the all-solid-state thin film lithium secondary battery becomes large. As described above, it is extremely difficult to increase the amount of the electrode active material by the conventional vapor deposition method, and it has been impossible to provide a practical lithium secondary battery having high energy at low cost.

  In order to solve these problems, an organic polymer binder is added to the electrolyte powder to be used in the configuration of the lithium ion conductive electrolyte layer in order to give flexibility to the lithium ion conductive electrolyte layer to be used and to improve its workability. Various flexible sheet formations have been studied. However, in any case, inside the prepared solid electrolyte sheet, there are grain boundaries at the junction interface between the electrolyte particles, and even if an all-solid lithium secondary battery is configured using this, In the charge / discharge cycle life, particularly in the deep charge / discharge cycle, due to the phenomenon as described above, that is, due to the difference in current density distribution inside the battery, the electrode volume change is extremely large in the portion where the current density distribution is strong, and the electrode Electronic bonding inhibition at the active material / electrolyte particle bonding interface occurs.

  In addition, in a battery system that uses a reversible precipitation reaction of lithium metal as a reaction of the negative electrode active material to be used, lithium ions are precipitated in the form of a tree-like lithium metal at the joint grain boundary between the electrolyte powder particles in the electrolyte layer. To do. As a result, in such an all-solid lithium secondary battery, the charge / discharge output current density is lowered with the charge / discharge cycle, and the capacity is also lowered for a while. In addition, the deposited lithium-like lithium metal has various problems such as causing an electrical short circuit between the positive electrode and the negative electrode by spreading the interface between the electrolyte particles and precipitating between them.

In addition, in a solid electrolyte sheet prepared by adding an organic polymer binder, the lithium ion conductivity tends to be extremely lower than that of a solid electrolyte alone to which no binder is added, and the lithium ion conductive solid electrolyte to be used Therefore, it was necessary to use a material having excellent ion conductivity as much as possible.
Therefore, for _{example, Li 2 S-SiS 2,} Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 - _{LiI, Li 2 S-SiS 2} -P 2 S 5 -LiI, Li 2 S-B 2 S 3, Li 2 S-B 2 S 3 -LiI, Li 2 S-P 2 S 5, Li 2 S-P _{2 S 5 -LiI, Li 2 S} -P 2 S 5 -ZmSn (Z = Ge, Zn, Ga), Li 2 S-GeS 2, Li 2 S-SiS 2 -Li 3 PO 4, Li 2 S-SiS _2- LixPOy (M = P, Si, Ge, B, Al, Ga, In) -based sulfide lithium ion conductive solid electrolyte glass, crystalline lithium ion conductor containing these components, or a mixture thereof Lithium ion conductive solid electrolyte consisting of From the viewpoint of material with Ion _{conductivity, Li 2 S-B 2 S} 3, Li 2 S-P 2 S 5 other multi-component system lithium ion conductive solid electrolyte materials have been studied.
However, most of them have used a semiconductor material such as Si, Ge, LiI or the like containing lithium halide as a constituent material.

As a sulfide-based lithium ion conductive solid electrolyte material showing excellent ion conductivity, there are many materials containing Si and Ge, and when this is used as an electrolyte of an all-solid lithium secondary battery, in its charge / discharge reaction, Particularly in the negative electrode, since Si and Ge undergo reduction near the potential at which the reduction of lithium ions to metallic lithium proceeds, commonly used carbon can be used as the negative electrode active material for lithium ion batteries. Absent. Accordingly, In, which is a material having a higher reversible reaction potential than lithium, has been used as the negative electrode active material reaction.
As a result, the operating voltage of the constructed battery was lower than that using carbon as the negative electrode. That is, as compared with a battery using carbon as a negative electrode material, the cost is high and the all-solid lithium secondary battery has a low operating voltage.

  In addition, when a sulfide-based lithium ion conductor containing lithium iodide is used as an electrolyte of an all-solid lithium secondary battery as a sulfide-based lithium ion conductive solid electrolyte material, In the positive electrode, the oxidation-reduction reaction of iodine proceeds at about 3.0 V, and inhibits the reaction (about 4.2 V) when lithium cobaltate is used as the positive electrode active material, for example. Therefore, a material exhibiting a high potential charge / discharge reaction could not be used as the positive electrode active material, and only an all solid lithium secondary battery having a low operating voltage could be constructed.

  In order to eliminate such problems in the negative electrode and the positive electrode, the inventors of the present invention add α-alumina to various sulfide-based lithium ion conductors as the ionic conductivity of the sulfide-based lithium ion conductive solid electrolyte. As a result, it has been found that ion conductivity can be improved, and an all-solid secondary battery using this electrolyte has been researched and developed. The present invention further eliminates the grain boundary between the solid electrolyte particles remaining when the electrolyte is molded, thereby improving the grain boundary bonding problem at the interface between the electrolyte particles and having practical performance with excellent performance. It is intended to provide an all-solid-state lithium secondary battery that is rich in materials.

  SUMMARY An advantage of some aspects of the invention is to solve at least the above-described problems, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A sulfide-based lithium ion conductive solid electrolyte glass according to this application example is characterized in that the sulfide-based lithium ion conductive solid electrolyte contains α-alumina.

  According to this, the sulfide-based lithium ion conductive solid electrolyte glass is obtained by heating and melting a material composed of a mixture of α-alumina and a sulfide-based lithium ion conductive solid electrolyte, followed by rapid cooling. Lithium ion conductive solid electrolyte. As a result, the ionic conduction is disordered (no anisotropy) in the solid electrolyte glass, and the ionic conductivity of the solid electrolyte layer made of a powder molded body using these is simply higher than that of a mixture of these materials. , Can be improved to a better electrolyte.

  Application Example 2 In the sulfide-based lithium ion conductive solid electrolyte glass according to the application example, the sulfide-based lithium ion conductive solid electrolyte glass is lithium sulfide-phosphorus sulfide and α-alumina, or lithium sulfide-boron sulfide. And α-alumina.

  According to this, the sulfide-based lithium ion conductive solid electrolyte glass has an ionic conductivity of a binary sulfide-based lithium ion conductor made of lithium sulfide-phosphorus sulfide and α-alumina or lithium sulfide-boron sulfide. Since it can be improved, the working voltage of the all-solid-state lithium secondary battery is high, and a highly practical battery capable of high rate discharge can be provided.

  Application Example 3 An all-solid lithium secondary battery according to this application example is characterized in that sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina is used as a solid electrolyte layer.

  [Application Example 4] The all-solid lithium secondary battery according to this application example uses a sulfide-based lithium ion conductive solid glass containing lithium sulfide-phosphorus sulfide or lithium sulfide-sulfuric boric acid as a solid electrolyte layer. It is characterized by that.

  [Application Example 5] The all-solid lithium secondary battery according to this application example uses an all-solid lithium secondary battery element in which the solid electrolyte layer is interposed between a pair of electrodes composed of a positive electrode layer and a negative electrode layer. And

  [Application Example 6] The all-solid lithium secondary battery according to this application example uses an all-solid lithium secondary battery element in which either the positive electrode layer or the negative electrode layer and the solid electrolyte layer are integrally formed. Features.

  According to this, by using the sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina as the solid electrolyte layer of the all-solid lithium secondary battery, the all-solid lithium having excellent performance in charge and discharge rate. A secondary battery can be provided.

  [Application Example 7] The manufacturing method of an all-solid lithium secondary battery according to this application example is described in any one of Application Examples 1 to 3 between at least a pair of electrodes including a positive electrode layer and a negative electrode layer. The all-solid-state lithium secondary battery element in which the sulfide-based lithium ion conductive solid electrolyte glass is interposed, or at least one of the positive electrode layer and the negative electrode layer, and at least one of Application Example 1 and Application Example 2 Sulfide-based lithium ion conductive material comprising α-alumina, which is an all-solid lithium secondary battery element or electrode layer and electrolyte layer integrally formed by heating and compressing a solid-based lithium ion conductive solid electrolyte glass layer Sulfide-based lithium ion conduction comprising: a first step of heating and melting a solid electrolyte mixture; and a second step of rapidly cooling the heating and melting mixture. Characterized in that it comprises a manufacturing process of the solid electrolyte glass.

  [Adaptation example 8] In addition to the above manufacturing method, the manufacturing method of the all-solid lithium secondary battery according to this application example is based on either the positive electrode layer or the negative electrode layer, and the sulfide-based lithium ion conductive solid electrolyte glass. It includes a third step of forming an all-solid lithium secondary battery element in which the electrode layer and the electrolyte layer are integrally molded by heating and compressing the generated electrolyte glass powder.

  According to this, the manufacturing method of the all-solid lithium secondary battery can be obtained simply by using the sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina as the electrolyte of the all-solid lithium secondary battery. A battery having a low battery internal resistance can be provided as compared with those using a sulfide-based lithium ion conductive solid electrolyte containing alumina. Furthermore, the above-mentioned electrolyte glass powder used here becomes a single glass plate-like electrolyte layer by heat-compressing, and therefore, there is little interface between electrolyte powder particles in the layer, and the ionic conductivity is low. An improved high glassy solid electrolyte layer can be obtained. Therefore, these electrolyte glass powders are interposed between a pair of electrodes consisting of a positive electrode and a negative electrode of an all-solid-state lithium secondary battery in a layered manner. By performing heating and compression processes during integral molding, there are few joint grain boundaries at the joint interface between electrolyte powders in the battery, and an electrolyte layer and an electrode layer excellent in ion conductivity are formed. An all-solid lithium secondary battery element that is integrally formed can be formed, and can be provided using the above-mentioned all-solid lithium secondary battery element, and can be provided with excellent charge / discharge cycle performance. A secondary battery can be provided.

  [Application Example 9] In the method for manufacturing an all-solid lithium secondary battery according to the application example, the temperature condition for the heating is within the glass softening temperature range of the sulfide-based lithium ion conductive solid electrolyte glass. The heating is preferably performed in a time range in which the crystallization of the sulfide-based lithium ion conductive solid electrolyte glass does not proceed.

  According to this, the manufacturing method of the all-solid-state lithium secondary battery can be easily formed by press-molding the sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina in layers in the above-mentioned glass softening temperature region. The glassy solid electrolyte layer with few grain boundaries can be formed. For this reason, the ionic conductivity of the solid electrolyte layer can be improved. Also, the electrode active material particles and the electrolyte particles can be smoothly joined inside the electrode, and an all-solid lithium secondary battery element having excellent charge / discharge cycle performance can be provided. It becomes possible to provide the all-solid lithium secondary battery shown.

  [Application Example 10] In the method for manufacturing an all-solid lithium secondary battery according to the application example, the heating temperature is 200 ° C. to 300 ° C., and the heating time is 5 hours or less. preferable.

  According to this, the all-solid lithium secondary battery needs to avoid crystallization of the solid electrolyte layer, and in the method for manufacturing the all-solid lithium secondary battery, the heating temperature is interposed in the layered manner. In the softening temperature region of the electrolyte glass powder, it is necessary to heat for a time during which the sulfide-based lithium ion conductive solid electrolyte glass powder layer does not crystallize. Softening of the solid electrolyte glass occurs at or above the glass transition temperature of the solid electrolyte glass. In the temperature region where crystallization proceeds, the higher the temperature, the easier the crystallization of the electrolyte glass proceeds, and it is necessary to shorten the heat treatment time.

  The heating temperature is within the softening temperature range of the sulfide-based lithium ion conductive solid electrolyte glass powder layer, and is preferably treated at 200 ° C to 300 ° C. Furthermore, it is preferable to heat for a time during which the sulfide-based lithium ion conductive solid electrolyte glass powder layer does not crystallize, and the processing time is preferably within 5 hours in view of the battery manufacturing process.

  According to such a method, it is possible to avoid crystallization of the sulfide-based lithium ion conductive solid electrolyte glass layer and to have excellent lithium ion conductivity. In addition, since the sulfide-based lithium ion conductive solid electrolyte glass powder is in a softened state, it is possible to smoothly join the joint surfaces with different layers.

  Application Example 11 In the method for manufacturing an all-solid lithium secondary battery according to the application example, the fourth step of sealing the all-solid lithium secondary battery element with a low-melting glass having a softening temperature of 350 ° C. or lower. It is preferable to provide.

  According to this, the manufacturing method of the all-solid lithium secondary battery includes the step of enclosing the periphery of the all-solid lithium secondary battery element with the low-melting glass, thereby sealing the all-solid lithium secondary battery that is a hygroscopic battery. Pore treatment is also possible, and mixing of moisture in the manufacturing process of an all-solid lithium secondary battery can be avoided, and the battery performance can be prevented from being lowered. As a result, the industrial value relating to manufacturing is extremely increased.

[Application Example 12] In the method for manufacturing an all-solid lithium secondary battery according to the application example, it is preferable that the low-melting glass is a glass composed of four components of V ₂ O ₅ , ZnO, BaO and TeO _2. .

According to this, the manufacturing method of the all-solid lithium secondary battery uses an all-solid-state lithium secondary battery that uses low melting point glass composed of at least four components of V ₂ O ₅ , ZnO, BaO, and TeO _2. In the heat compression treatment step, since the performance of the produced battery is rarely lowered, it is preferably selected.

  According to such a method, it is possible to avoid crystallization of the sulfide-based lithium ion conductive solid electrolyte glass layer due to thermal transition when melting the low melting point glass, and it is possible to prevent a decrease in ion conductivity of the electrolyte layer.

  [Application Example 13] In the method for manufacturing an all-solid lithium secondary battery according to the application example, the first step, the second step, the third step, and the fourth step are dry and inert. It is preferable to perform the continuous treatment in a gas atmosphere.

  According to this, the manufacturing method of an all-solid-state lithium secondary battery is provided with each formation process which forms each sulfide type lithium ion conductive solid electrolyte glass layer, a positive electrode layer, and a negative electrode layer, and each formation process is integrated. In the treatment step, the treatment is continuously carried out in a dry inert gas atmosphere.

  As described above, the all-solid lithium secondary battery includes an all-solid lithium secondary battery having a pair of positive and negative electrodes and a sulfide-based lithium ion conductive solid electrolyte glass layer provided between the positive and negative electrodes. A battery, which is manufactured by the method of any one of Application Examples 7 to 13.

  The all-solid-state lithium secondary battery is produced using this sulfide-type lithium ion conductive solid electrolyte glass containing α-alumina, and a layer made of this electrolyte glass powder is at least between the positive electrode layer and the negative electrode layer. Or at least one of the positive electrode layer and the negative electrode layer is laminated, heated, and compressed to integrate them. As a result, the bonding at the bonding interface between different layers becomes dense, and the charge / discharge output current density can be increased in the charge / discharge performance of the produced all-solid lithium secondary battery. At the same time, the bonding interface between the electrolyte powders can be eliminated in the electrolyte glass layer.

  As a result, in particular, in a battery system that uses a reversible deposition reaction of metallic lithium as a negative electrode reaction, it is possible to prevent metal-like deposition of metallic lithium at the negative electrode interface, which is likely to occur at the time of overcharging. Can be avoided. The process of heating and compressing and integrating these different layers is easy, and it is possible to supply products with excellent charge / discharge cycle life in the performance of the prepared all-solid lithium secondary battery. This makes it possible to produce an all-solid-state lithium secondary battery having a high technical value.

  As described above, when a sulfide-based lithium ion conductive solid electrolyte containing α-alumina is used, a sulfide-based lithium ion conductive solid electrolyte glass having lithium ion conductivity superior to that of a sulfide-based lithium ion conductor alone. Can be formed. Here, a sulfide-based lithium ion conductive solid electrolyte glass is produced by heating and melting a mixture of a sulfide-based lithium ion conductive solid electrolyte containing α-alumina and then rapidly cooling the melt. A solid electrolyte layer made of an electrolyte glass powder produced from sulfide-based lithium ion conductive glass containing α-alumina, and at least one of a positive electrode layer and a negative electrode layer are laminated, heated, and compressed. By integrating, the junction at the interface between different layers can be made dense, and the charge / discharge output current density can be increased in the performance of the produced battery.

Further, as a sulfide-based lithium ion conductive solid electrolyte containing α-alumina, a material not containing Si, Ge, for example, Li ₂ S—P ₂ S ₅ , Li ₂ S—B ₂ S ₅ or the like is used. When an all-solid lithium secondary battery is constituted, it is possible to use a reversible deposition reaction of metallic lithium as the reaction at the negative electrode, which is preferable.

  Furthermore, since these do not contain halides such as lithium iodide, the reaction at the positive electrode is not affected by the oxidation-reduction reaction of halides, so it is possible to use an electrode active material that exhibits a high charge / discharge reaction, It becomes more preferable. Using the materials as described above, there is no interfacial bonding between the electrolyte powder particles inside the electrolyte layer inside the created battery, especially in battery systems that use a reversible deposition reaction of metallic lithium as the negative electrode electrode reaction. This leads to the prevention of metallic lithium-like precipitation at the negative electrode interface, which is likely to occur, and as a result, an electrical short circuit between the positive electrode and the negative electrode can be avoided.

  The process of heating and compressing and integrating these different layers is easy, and it is possible to supply products with excellent charge / discharge cycle life in the performance of the prepared all-solid lithium secondary battery. This makes it possible to produce an all-solid lithium secondary battery with high target value. Further, the sulfide-based lithium ion conductive solid electrolyte glass used in the present invention is based on a mixed electrolyte containing α-alumina in a sulfide-based lithium ion conductive solid electrolyte that has already been proposed by the inventors. As a result of studying vitrification of the mixed electrolyte, it has become possible to produce it. All of the above mixed electrolyte containing α-alumina disclosed can be vitrified, and by using the above vitrified sulfide-based lithium ion conductive solid electrolyte, all-solid lithium secondary batteries having excellent battery performance can be obtained. The secondary battery can be manufactured.

  [Application Example 14] The method for integrally forming an electrode and an electrolyte layer according to this application example is at least one of Application Examples 1 to 2 between a pair of electrodes including a positive electrode layer and a negative electrode layer. The all-solid-state lithium secondary battery element in which the solid electrolyte layer made of the sulfide-based lithium ion conductive solid electrolyte glass is interposed is formed. At least one of the positive electrode layer and the negative electrode layer and at least a layer made of the electrolyte glass powder formed from the sulfide-based lithium ion conductive solid electrolyte glass described in any one of Application Example 1 and Application Example 2 is heated and compressed. Thus, the all solid lithium secondary battery element in which the electrode layer and the electrolyte layer are integrally molded can be formed.

  According to this, the above-mentioned method for integrally forming the electrode electrolyte layer is simply by using a sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina as an electrolyte of an all-solid lithium secondary battery. -A battery having a low battery internal resistance can be provided as compared with those using a sulfide-based lithium ion conductive solid electrolyte containing alumina. Furthermore, since the electrolyte glass powder produced from the use here is heated and compressed into a single glass plate-like electrolyte layer, the interface between the electrolyte powder particles is eliminated in the layer, and the ionic conductivity is improved. A single glassy solid electrolyte layer is obtained. For this reason, the above-described method of integrally forming the electrode and the electrolyte layer is obtained by interposing these electrolyte glass powders in layers between a pair of electrodes consisting of a positive electrode and a negative electrode of an all-solid lithium secondary battery. When a secondary battery element is formed, or when an electrode and an electrolyte layer are integrally formed, by adding a heat compression step, there is no bonding grain boundary at the bonding interface between electrolyte powders inside the battery, and ion conductivity It is possible to form an all-solid lithium secondary battery element having a solid electrolyte layer made of a solid electrolyte glass excellent in the above. By using the all-solid lithium secondary battery so that an all-solid lithium secondary battery can be provided, excellent charge / discharge cycle performance can be imparted.

  [Application Example 15] In the method of integrally forming the electrode and the electrolyte layer according to the application example, the temperature condition for the heating is within the range of the glass softening temperature range of the sulfide-based lithium ion conductive solid electrolyte glass. In addition, the heating is preferably performed in a time range in which the crystallization of the sulfide-based lithium ion conductive solid electrolyte glass does not proceed.

  According to this, the above-mentioned method of integrally forming the electrode and the electrolyte layer can be easily performed by press-molding into layers in the softening temperature region of sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina. In addition, it is possible to produce a solid electrolyte layer of plate glass having no grain boundary in the electrolyte layer. For this reason, the ionic conductivity of the electrolyte layer can be improved. Therefore, when creating an all-solid lithium secondary battery element in which these electrolyte glass powders are layered between a pair of electrodes consisting of a positive electrode and a negative electrode of an all-solid lithium secondary battery, or the electrode and the electrolyte layer are integrated. When molding, by heating and compressing in the softening temperature region of the sulfide-based lithium ion conductive solid electrolyte glass powder, it can be a bonding layer without grain boundaries in the electrolyte layer. The joining of the electrode active material particles and the electrolyte particles will be smooth, and an all-solid lithium secondary battery having excellent charge / discharge cycle performance will be provided. A secondary battery can be provided.

  [Application Example 16] In the method of integrally forming an electrode and an electrolyte layer according to the application example, the heating temperature is 200 ° C. to 300 ° C., and the heating time is 5 hours or less. Is preferred.

  According to this, the method of integrally forming the electrode and the electrolyte layer needs to avoid crystallization of the solid electrolyte layer inside the all-solid lithium secondary battery element, and the temperature at which the heating is performed is the sulfide-based lithium. Although it is the softening temperature range of the ion conductive solid electrolyte glass powder layer, it is necessary to heat for a time during which the sulfide-based lithium ion conductive solid electrolyte glass powder layer does not crystallize. Softening of the solid electrolyte glass occurs at or above the glass transition temperature of the solid electrolyte glass. In the temperature region where crystallization proceeds, the higher the temperature, the easier the crystallization of the electrolyte glass proceeds, and it is necessary to shorten the heat treatment time.

  The heating temperature is in the softening temperature region of the sulfide-based lithium ion conductive solid electrolyte glass powder layer, and is preferably treated at 200 to 300 ° C. Furthermore, it is preferable to heat for a time during which the sulfide-based lithium ion conductive solid electrolyte glass powder layer does not crystallize, and the time for performing the heating is preferably within 5 hours in consideration of the battery manufacturing process.

  According to such a method, it is possible to avoid crystallization of the sulfide-based lithium ion conductive solid electrolyte glass and to have excellent lithium ion conductivity. In addition, since the sulfide-based lithium ion conductive solid electrolyte glass powder is in a softened state, it is possible to smoothly join the joint surfaces with different layers.

  Hereinafter, an embodiment of the present invention will be described in detail for a method for producing an all-solid lithium secondary battery. First, a method for producing a sulfide-based lithium ion conductive solid electrolyte glass used as an electrolyte layer of an all-solid lithium secondary battery will be described using Embodiment 1.

(Embodiment 1)
The sulfide-based lithium ion conductive solid electrolyte used in Embodiment 1 is a glassy electrolyte containing α-alumina in a sulfide-based lithium ion conductive solid electrolyte, and the base lithium ion conductive solid electrolyte is: For example, Li ₂ S—SiS ₂ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS ₂ —LiBr, Li ₂ S—SiS ₂ —LiCl, Li ₂ S—SiS ₂ —B ₂ S ₃ —LiI, Li ₂ S—SiS ₂ —P ₂ S ₅ —LiI, Li ₂ S—B ₂ S ₃ , Li ₂ S—B ₂ S ₃ —LiI, Li ₂ S—P ₂ S ₅ , Li ₂ S—P ₂ S _{5 -LiI, Li 2 S-P} 2 S 5 -ZmSn (Z = Ge, Zn, Ga), Li 2 S-GeS 2, Li 2 S-SiS 2 -Li 3 PO 4, Li 2 S-SiS 2 - LixPOy (M = P, Si, Ge, B, Al, Ga, In) Hydride lithium-ion-conducting solid electrolyte glass, and crystalline lithium ion conductor comprising these components, or a lithium ion conductive solid electrolyte consisting of the mixture is chosen.

Next, α-alumina having a particle diameter of 10 μm or less, which is an insulating fine particle, is mixed with the sulfide-based lithium ion conductive solid electrolyte as a base material. The α-alumina used here was heated at 250 ° C. for 5 hours in a high vacuum to remove water that was supposed to be adsorbed on the surface.
A predetermined amount of these were weighed, and the mixture added to the sulfide-based lithium ion conductor was prepared. The prepared mixture was further mixed and pulverized by a planetary ball mill. The pot of the planetary ball mill used here was made of alumina, and the balls contained therein were alumina balls having a diameter of 5 mm and 10 mm.

Next, when vitrification is performed using these sulfide lithium ion conductive solid electrolyte and the prepared α-alumina, the following two methods are applied.
That is, (1) A sulfide-based lithium ion conductive solid electrolyte powder containing the prepared α-alumina is filled in a glassy carbon crucible, and this is vacuum-sealed in a quartz tube. The vacuum ampule was inserted into an electric furnace and heated and melted at about 850 ° C. for about 3 hours. Thereafter, a vacuum ampule was inserted into ice water, and the melt in the glassy carbon crucible was rapidly cooled to obtain a sulfide-based lithium ion conductive solid electrolyte glass containing α-alumina.

As another vitrification method, (2) after filling the glassy carbon crucible with the sulfide-based lithium ion conductive solid electrolyte powder containing the prepared α-alumina, the crucible is connected to a glove box in an electric furnace. The quartz tube was inserted while ventilating dry argon gas, and the crucible was heated at about 850 ° C. for about 3 hours to melt the sulfide-based lithium ion conductive solid electrolyte powder containing α-alumina. After that, the crucible is taken out from the quartz tube, and the melt in the crucible is poured into a stainless steel twin roller provided in the glove box so that the melt is rapidly cooled to provide sulfide-based lithium ion conductive solid electrolyte glass. Can be made.
In the rapid cooling of this melt, it enters the softening temperature region from the molten state, and in this state, it becomes a flexible plate, but after passing through this process, it reaches below the glass transition temperature, and it is a single hard sheet It becomes plate-like glass, and a desired sulfide lithium ion conductive glass can be obtained.

All the vitrification processes using these twin rollers used an electric furnace attached to a dry box in a dry argon atmosphere, and all the sample preparation processes were processed in the dry box. The sulfide-based lithium ion conductive solid electrolyte thus prepared is pulverized, and the powder is used to fill an alumina mold having a cylinder with a diameter of 1 cm. While heating to the softening temperature (about 200 ° C. to 320 ° C.) of the ion conductive solid electrolyte glass, it was pressure-molded at a pressure of about 2 ton / cm ² .
Here, the used male mold for molding was a stainless steel plated with gold. After the molding was cooled to room temperature, its ionic conductivity was measured under the pressure.

  Hereinafter, the sulfide-based lithium ion conductive solid electrolyte glass of Embodiment 1 will be described with reference to examples in order to describe it in more detail.

Example 1
Here, using a lithium ion conductive glass made of Li ₂ S—SiS ₂ —Li ₃ PO ₄ as a sulfide-based lithium ion conductor, which is a starting base material, an insulating property is obtained by the method described in (1) above. A new sulfide-based lithium ion conductive solid electrolyte glass in which α-alumina was mixed at a weight ratio of 7% as part particles was formed.

The obtained sulfide-based lithium ion conductive solid electrolyte glass was pulverized with a planetary ball mill to an average particle size of about 7 μm, and the obtained solid electrolyte powder had a cylinder with a diameter of 1 cm that also served as an ion conductivity measurement cell. An alumina molding jig was filled and pressure molded at a pressure of 2 ton / cm ² . In this pressurization, the jig is heated while being heated (processed within 2 hours) within the softening temperature range (approximately 200 ° C to 320 ° C) of the sulfide-based lithium ion conductive solid electrolyte glass. did.
Here, the used male mold for molding was a stainless steel plated with gold. Subsequently, while maintaining the pressurized state, the measurement cell was cooled to room temperature, and then its ionic conductivity was measured. Moreover, when the solid electrolyte pellet was taken out from the measurement cell after measuring the ionic conductivity, the pellets prepared at a heating temperature of 200 ° C. to 320 ° C. or less were all obtained as a light brown transparent disk. That is, in the electrolyte layer, it is a single transparent plate-like lithium ion conductive glass having no grain boundary bonding, and those prepared at 180 ° C. and 350 ° C. showed an opaque white state of the electrolyte.

When the ionic conductivity of the prepared electrolyte was measured, a transparent plate obtained by processing within a heating range of 200 ° C. to 320 ° C., the pressure applied during the measurement was 2 ton / Despite the low pressure of cm ² , the ionic conductivity showed an excellent value of 1.7 × 10 ⁻³ S / cm ² or more.
On the other hand, the white opaque electrolyte produced by heating and compressing at 350 ° C. showed 0.95 × 10 ⁻⁴ S / cm ^2, and it was found that the ionic conductivity was extremely lowered. However, the white opaque electrolyte layer obtained by warm compression at 180 ° C. showed 1.1 × 10 ⁻³ S / cm ² .
This is because the electrolyte powder crystallized in the treatment at 350 ° C., and the electrolyte powder does not soften in the treatment at 180 ° C. It was thought that it was not a glass plate without grain boundaries.
On the other hand, when the electrolyte powder obtained by simply mixing α-alumina, which is a conventional electrolyte, with the electrolyte base material used in Example 1 is molded at a pressure of 2 ton / cm ² , its ionic conductivity is 0. indicates .9 × 10 ^-3 S / cm ^2, by molding a molding pressure 4 t / cm ² of pressure or more, began to show a ^{2.5 × 10 -3 S / cm 2} .
That is, this is a value that can only be obtained by applying a pressure of 4 ton / cm ² or more to the electrolyte powder as the ionic conductivity, and the color of the formed electrolyte is a white disk. The grain boundary bonding between the electrolyte powder particles was not eliminated, and an opaque white color was exhibited.

The obtained characteristics are collectively shown in FIG. From this result, when an electrolyte powder obtained by simply mixing α-alumina is used, if a pressure of 4 ton / cm ² or more is applied and the pressure is not maintained, an electrolyte layer in an all-solid lithium secondary battery can be obtained. On the other hand, it can be said that a practical electrolyte layer can be easily formed when the electrolyte glass powder of the present invention is used to constitute an electrolyte layer, although it does not have practical battery performance.

(Example 2)
Here, in order to investigate the relationship between the heating temperature and time in the heating and compression molding of the electrolyte glass used in Example 1, an electrolyte glass molded body was similarly prepared, its conductivity was measured, and its appearance was examined. It was. However, the molding pressure used here was 2 ton / cm ² as in Example 1.
The obtained results are collectively shown in FIG. As a result, when heating and compressing in the temperature range of 180 ° C. to 350 ° C. as the heating temperature, the ion conductivity is 1 × 10 ⁻³ S / cm ² or more for all glass molded bodies within a treatment time of 6 hours. It was found that However, when the treatment temperature is 300 ° C. and the treatment time exceeds 5 hours, a slight decrease in ionic conductivity is observed in this temperature region.
It has been found that the treatment temperature is preferably in the temperature range of 200 ° C. to 300 ° C., and the treatment time is preferably within 5 hours. At 180 ° C., since the appearance of the electrolyte molded body was opaque white, it is considered that grain boundary bonding existed in the electrolyte layer, which is not a preferable state.

(Example 3)
Here, using a lithium ion conductive glass made of Li ₂ S—Ge ₂ S ₂ —P ₂ S ₅ as a sulfide-based lithium ion conductor as a starting base material, the method described in (1) above, A new sulfide-based lithium ion conductive solid electrolyte glass in which α-alumina was mixed at a weight ratio of 7% as insulating part particles was similarly constructed.

The obtained sulfide-based lithium ion conductive solid electrolyte glass (hereinafter also referred to as electrolyte glass) with a planetary ball mill was crushed to an average particle size of about 7 μm, and a solid electrolyte powder serving as an ion conductivity measuring cell was 1 cm in diameter. Filled in an alumina mold having a cylindrical shape, and heated to the softening temperature (about 220 ° C.) of the sulfide-based lithium ion conductive solid electrolyte glass produced with this mold (within 2 hours of heating time) Treatment), and pressure-molded at a pressure of about 2 tons / cm ² .
Here, the used male mold for molding was a stainless steel plated with gold. Subsequently, while maintaining the pressurized state, the measurement cell was cooled to room temperature, and then its ionic conductivity was measured. When the solid electrolyte pellet was taken out from the measurement cell after the ionic conductivity measurement, the solid electrolyte pellet was a light brown transparent disk. Also in this case, it was found that the sheet was a single plate-like lithium ion conductive glass having no grain boundary bonding in the electrolyte layer.

As a result of measuring the ionic conductivity of the prepared electrolyte glass, the ionic conductivity was excellent at 3.3 × 10 ⁻³ S / cm ² , regardless of the pressure applied at the time of measurement was as low as 2 ton / cm ² . The value is shown. On the other hand, the ionic conductivity of the electrolyte powder obtained by simply mixing the conventional α-alumina with the base material was measured in the same manner, and when compared, this value was 4 ton / cm ^{2 in the} ionic conductivity measuring cell. It was a value that could not be obtained without applying the above pressure.
That is, the electrolyte powder obtained by simply mixing α-alumina is about 3.0 × 10 ⁻³ S / cm ² by applying a pressure of 4 ton / cm ² or more to the measurement cell. It has been found that, when a conventional electrolyte layer is molded, if the pressure does not exceed this pressure, it is affected by grain boundary bonding inside the electrolyte. Moreover, after the measurement, the electrolyte molded body in the cell was taken out, and a light brown opaque disk was obtained. That is, it was considered that the grain boundary bonding between the electrolyte powder particles was not eliminated in the molded body, and a light brown opaque state was exhibited.

Example 4
Here, as a starting base material, lithium ion conductive glass composed of Li ₂ S—P ₂ S ₅ is used as a sulfide-based lithium ion conductor, and the insulating part particles are formed by the method described in (1) above. A new sulfide-based lithium ion conductive solid electrolyte glass in which α-alumina was mixed at a weight ratio of 7% was constructed.

The obtained electrolyte glass was pulverized with a planetary ball mill to an average particle size of about 7 μm, and this powder was filled into an alumina mold having a 1 cm diameter cylinder also serving as an ionic conductivity measuring cell, and sulfided. The material lithium ion conductive solid electrolyte glass was press-molded at a pressure of about 2 ton / cm ² while being heated (treated within 2 hours of heating time) in the softening temperature region (about 220 ° C.).
Here, the used male mold for molding was a stainless steel plated with gold. Subsequently, while maintaining the pressurized state, the measurement cell was cooled to room temperature, and then its ionic conductivity was measured. Further, when the solid electrolyte pellet was taken out of the measurement cell after measuring the ionic conductivity, the solid electrolyte pellet was obtained as a light brown transparent brownish brown disk. Also in this case, it was found that the sheet was a single plate-like lithium ion conductive glass having no grain boundary bonding in the electrolyte layer.

As a result of measuring the ionic conductivity of the prepared electrolyte glass, the ionic conductivity was 0.85 × 10 ⁻³ S / cm regardless of the pressure applied at the time of measurement being as low as 2 ton / cm ^2. Excellent value was shown. On the other hand, the ionic conductivity of the electrolyte powder obtained by simply mixing the conventional α-alumina with this base material was measured in the same manner. It was found that the value could not be obtained unless a pressure of cm ² or more was applied.
That is, when electrolyte powder obtained by simply mixing α-alumina is used, the pressure does not reach about 0.7 × 10 ⁻³ S / cm ² unless a pressure of 4 ton / cm ² or more is applied to the measurement cell. It has been found that, when a conventional electrolyte layer is molded, if this pressure is not applied, the inside of the electrolyte is affected by grain boundary bonding. Moreover, when the molded electrolyte in the cell was taken out after the measurement, a brownish brown opaque disk was obtained. That is, it was considered that the grain boundary bonding between the electrolyte powder particles was not eliminated inside the molded body, and a brownish brown opaque state was exhibited.

(Example 5)
Here, using the lithium ion conductive glass made of Li ₂ S—P ₂ S ₅ —LiI as the sulfide-based lithium ion conductor as a starting base material, the insulating part particles are obtained by the method described in the above (1). A new sulfide-based lithium ion conductive solid electrolyte glass in which α-alumina was mixed at a weight ratio of 7% was prepared.

The obtained electrolyte glass was pulverized with a planetary ball mill to an average particle size of about 7 μm, and this powder was filled into an alumina mold having a 1 cm diameter cylinder also serving as an ion conductivity measurement cell. The sulfide-based lithium ion conductive solid electrolyte glass was subjected to pressure molding at a pressure of about 2 ton / cm ² while being heated (treated within 2 hours of heating time) to the softening temperature (about 220 ° C.).
Here, the used male mold for molding was a stainless steel plated with gold. Subsequently, while maintaining the pressurized state, the measurement cell was cooled to room temperature, and then its ionic conductivity was measured. When the solid electrolyte pellet was taken out of the measurement cell after measuring the ionic conductivity, a brown black transparent disk was obtained from the solid electrolyte pellet. Also in this case, it was found that the sheet was a single plate-like lithium ion conductive glass having no grain boundary bonding in the electrolyte layer.

As a result of measuring the ionic conductivity of the prepared electrolyte glass, the ionic conductivity was 1.1 × 10 ⁻³ S / cm regardless of the low pressure of 2 ton / cm ² during the measurement, which was extremely excellent. The value is shown. On the other hand, the ionic conductivity of the electrolyte powder obtained by simply mixing the conventional α-alumina with this base material was measured in the same manner, and when compared, this value was 4 ton / cm ^{2 in the} ionic conductivity measuring cell. It was found that the value could not be obtained without applying the above pressure.
That is, when an electrolyte powder obtained by simply mixing α-alumina is used, if the pressure of 4 ton / cm ² or more is not applied to the measurement cell, this ion conductivity is close to about 0.85 × 10 ⁻³ S / It did not become a cm ^2. It has been found that if a pressure higher than this pressure is not applied when forming a conventional electrolyte layer, the material is affected by grain boundary bonding inside the electrolyte. Moreover, when the molded electrolyte in the cell was taken out after the measurement, a dark brown opaque disk was obtained. That is, it was considered that the grain boundary bonding between the electrolyte powder particles was not eliminated inside the molded body, and a brown black opaque state was exhibited.

(Example 6)
Here, as a starting base material, lithium ion conductive glass made of Li ₂ S—B ₂ S ₃ is used as a sulfide-based lithium ion conductor, and the insulating part particles are formed by the method described in (1) above. A new sulfide-based lithium ion conductive solid electrolyte glass in which α-alumina was mixed at a weight ratio of 5% was constructed.

The obtained electrolyte glass was pulverized with a planetary ball mill to an average particle diameter of about 7 μm, and this was filled into an alumina mold having a diameter of 1 cm which also served as an ion conductivity measuring cell, and the sulfide was prepared. The mold was heated (treated within 2 hours of heating time) to the softening temperature (about 220 ° C.) of the physical lithium ion conductive solid electrolyte glass, and pressure-molded at a pressure of about 2 ton / cm ² . Here, the used male mold for molding was a stainless steel plated with gold. Subsequently, while maintaining the pressurized state, the measurement cell was cooled to room temperature, and then its ionic conductivity was measured. When the solid electrolyte pellet was taken out from the measurement cell after the ionic conductivity measurement, the solid potential pellet was a brown transparent disk. Also in this case, it was found that the sheet was a single plate-like lithium ion conductive glass having no grain boundary bonding in the electrolyte layer.

The measurement result of the ionic conductivity of the prepared electrolyte glass shows that the ionic conductivity is 1.0 × 10 ⁻³ S / cm, regardless of whether the pressure applied during the measurement is as low as 2 ton / cm ^2. The value was shown. On the other hand, the ionic conductivity of the electrolyte powder obtained by simply mixing the conventional α-alumina with this base material was measured in the same manner. It was found that the value could not be obtained unless a pressure of cm ² or more was applied.
That is, when an electrolyte powder obtained by simply mixing α-alumina was used, a pressure of 4 ton / cm ² or more was applied to the measurement cell to obtain about 0.9 × 10 ⁻³ S / cm ² . It has been found that, when a conventional electrolyte layer is molded, if this pressure is not applied, the inside of the electrolyte is affected by grain boundary bonding. Moreover, after the measurement, the electrolyte molded body in the cell was taken out, and a light brown opaque disk was obtained. That is, it was considered that the grain boundary bonding between the electrolyte powder particles was not eliminated inside the molded body, and a brown opaque state was exhibited.

In this example, Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₂ S—GeS ₂ —P ₂ S ₅ , Li ₂ S—P ₂ S ₅ , Li ₂ S—P ₂ S ₅ —LiI, Li _Using 5 types of sulfide lithium ion conductive solid electrolytes of ₂ S-B ₂ S ₃ , materials with α-Al ₂ O ₃ added thereto were synthesized, heated to their melting temperature range, and the melt It was found that vitrification was possible by rapid cooling of.
These phenomena are not limited to the sulfide lithium ion conductor used in this specific example, but are common to all materials in which α-alumina is mixed with the sulfide lithium ion conductor. It can be easily estimated that this is possible. In addition, from the results of measuring the ionic conductivity of each, the value is completely different from that obtained by molding a powdered sulfide-based lithium ion conductive solid electrolyte, and the formed electrolyte can be formed without applying high pressure. It has been found that since the layer is made of a single sheet of glass, the problem of electrolyte powder grain boundary bonding is eliminated and the ionic conductivity is improved.

As described above, as can be seen from the results of Examples 1 to 6 described above and the effect of the applied pressure for measuring the ionic conductivity of the electrolyte that does not vitrify, α-Al ₂ O ₃ is sulfided. All sulfide lithium ion conductors mixed into the product lithium ion conductor can be vitrified by heating to the melting temperature range and quenching the melt rapidly. However, it has been found that this can be said to be improved because there is no grain boundary in the electrolyte.
In addition, when electrolyte powder obtained by simply mixing α-alumina is used, if a pressure of 4 ton / cm ² or more is applied and the pressure is not maintained, it can be used as an electrolyte layer in an all-solid lithium secondary battery. Therefore, it is considered that an all-solid lithium secondary battery will not have excellent charge / discharge cycle performance unless the outer periphery of the battery element is strongly compressed. When the electrolyte glass powder of the present invention is used to construct and use an electrolyte layer without grain boundary bonding, it can be said that a practical all-solid lithium secondary battery can be obtained easily.

<All-solid lithium secondary battery>
Next, the all-solid lithium secondary battery of Embodiment 2 provided with the new sulfide lithium ion conductive glass thus obtained will be described.

(Embodiment 2)
This all-solid lithium secondary battery includes a sulfide-based lithium ion conductive solid electrolyte in which a sulfide-based lithium ion conductive solid electrolyte glass is formed in layers.

  FIG. 2 is a longitudinal sectional view of the all-solid lithium secondary battery of the present embodiment. The all-solid lithium secondary battery element shown in FIG. 2 is constructed by interposing a novel sulfide-based lithium ion conductive solid electrolyte glass layer (hereinafter referred to as electrolyte layer) 8 between the positive electrode (I) and the negative electrode (II). However, in this case, the intervening electrolyte layer 8 is formed so as to cover the positive electrode (I) and the negative electrode (II), and the positive electrode lead plate 1 and the negative electrode lead plate 5 are equivalent to the electrolyte layer 8. Or it is set as the form of a larger structure. Further, as a battery seal portion provided so as to cover almost the entire battery element (entire circumference), an insulating seal portion 10 separates the positive electrode terminal 9 and the negative electrode terminal 4 from each other and is sealed. ing.

Hereinafter, first, a battery element (battery element) having the positive electrode (I), the negative electrode (II), and the electrolyte layer 8 will be described. In this embodiment, the configuration of the positive electrode (I) and the negative electrode (II) is Since almost the same configuration is possible, the positive electrode (I) will be described as a representative with reference to FIG.
The positive electrode (I) is composed of electrode active material particles and solid electrolyte powder as an electrode material, and a positive electrode mixture 3 in which a conductive agent such as carbon is mixed, if necessary (the negative electrode (II) is a negative electrode mixture 7) ) Is used. The positive electrode mixture 3 and the negative electrode mixture 7 are used by being filled in a positive electrode current collector 2 and a negative electrode current collector 6 having voids such as a conductive net material.

At this time, the positive electrode current collector 2 and the negative electrode current collector 6 have not only the effect of imparting electronic conductivity for the purpose of equalizing the current and lowering the internal resistance, but also the expansion of the electrode that occurs during charging and discharging of the battery. It is more preferable to have an effect of reinforcing the contraction phenomenon and to be electrically bonded to the positive electrode lead plate 1 and the negative electrode lead plate 5.
Examples of the constituent material of the positive electrode current collector 2 and the positive electrode lead plate 1 include electron conductive metal materials such as Cu, Ni, Ti, and SUS, hard resin materials such as polycarbonate, ceramics such as alumina and glass, and the like. It is necessary to withstand the temperature when heating and compressing to the softening temperature of the electrolyte glass of an all-solid-state lithium secondary battery element, and when using an insulating material, It is preferable to add a conductive thin film.

  The current collector structure used here is shown in FIG. In the figure, 401 is a spot-welded positive electrode current collector 2 and negative electrode current collector 6 made of a metal mesh of the same size on the positive electrode lead plate 1 and negative electrode lead plate 5 having desired dimensions. In the drawing, reference numeral 402 denotes a spot welded positive electrode current collector 2 and negative electrode current collector 6 which are smaller than the dimensions of the positive electrode lead plate 1 and the negative electrode lead plate 5. Reference numerals 403 and 404 in the figure are structural materials in which the current collector structure 401 and the current collector structure 402 are provided with the restricting portion 11 in order to add mechanical strength to the outer peripheral portion of the electrode layer to be configured. An insulating material or a conductive material can be used, and the electrolyte layer 8 can also be used. The electrodes were prepared by appropriately selecting from these various current collector structures according to the battery structure.

Here, the metal mesh materials used as the positive electrode current collector 2 and the negative electrode current collector 6 are slightly different depending on the constituent materials, purposes, and the like, but the opening portion ratio is about 25% to 90% in plan view. It is preferable that it is about 70% to 85%. Furthermore, the average thickness is preferably about 10 μm to 400 μm, and more preferably about 50 μm to 300 μm.
In the electrode of the present embodiment, the positive electrode mixture 3 and the negative electrode mixture 7 are formed on the positive electrode current collector 2 and the negative electrode current collector 6 so as to cover almost the entire surfaces of the positive electrode current collector 2 and the negative electrode current collector 6. Filled.

The thickness of the positive electrode lead plate 1 and the negative electrode lead plate 5 used here is preferably about 300 μm to 500 μm. Examples of the positive electrode mixture 3 and the negative electrode mixture 7 include, for example, an electrode active material alone or a mixture (electrode mixture) containing an electrode active material and a solid electrolyte material, and, if necessary, carbon. These conductivity imparting materials can be mixed and used.
By using a mixture containing an electrode active material and a solid electrolyte material as the positive electrode mixture 3 and the negative electrode mixture 7, the electrode active material and the electrolyte glass powder constituting the positive electrode (I) or the negative electrode (II) By increasing the ion conductive bonding interface with the particles, the adhesion of the interface bonding force can be improved. As a result, the exchange of ions between the electrode and the electrolyte layer 8 can be performed smoothly, and the characteristics (charge / discharge characteristics) of the all-solid lithium secondary battery can be further improved.

The positive electrode active material used in the present embodiment, the lithium cobaltate (Li x CoO _2), lithium nickel oxide (Li x NiO _2), lithium cobalt nickel _{(LiCo 0.3 Ni 0.7 O 2)} , lithium manganate (LiMn ₂ O _4), titanium Lithium oxide (Li _4/3 Ti _5/3 O ₄ ), lithium manganate compound (LiM _y Mn _{2 -y} O ₄ ; M = Cr, Co, Ni), lithium iron phosphate and its compound (Li _1-x FePO ₄ , Li _1-x Fe _0.5 Mn _0.5 PO ₄ ) transition metal oxide material such as olivine compound, TiS ₂ , VS ₂ , FeS, Me.MoS ₈ (Me is Li, Ti, Cu, Sb, Sn, pb, sulfide chalcogenide such as transition metals), such as Ni, lithium metal to _{TiO 2, Cr 3 O 8,} V 2 O 5, MnO 2, CoO metal oxide, such as ₂ and a skeleton Product, and the like.
Further, as the negative electrode active material, carbon, metal materials such as lithium, indium, and aluminum, and alloys composed of these metals and lithium can be used alone or in combination of two or more.

When these electrode active materials and a novel solid electrolyte glass material are mixed and used, the novel solid electrolyte glass material may be the same (same) or different from the electrolyte layer 8 described later, but the same (especially the same). Is preferred. Thereby, while being able to perform the movement of the ion between positive electrode (I) and the electrolyte layer 8 more smoothly, the improvement of the adhesiveness can be aimed at further.
The mixing ratio of the electrode active material and the solid electrolyte glass material is not particularly limited, but is preferably about 4: 6 to 9: 1, more preferably about 5: 5 to 8: 2, by weight ratio. .

Moreover, as an electrode active material, the granular (powder) thing of 20 micrometers or less is used suitably. By using such a granular electrode mixture, the positive electrode mixture 3 and the negative electrode mixture 7 can be more easily and reliably filled into the gaps of the positive electrode current collector 2 and the negative electrode current collector 6.
The average thickness of the positive electrode mixture 3 and the negative electrode mixture 7 is preferably 30 μm or more and 500 μm or less, and more preferably 50 μm or more and 300 μm or less. This is because when the thickness of the positive electrode mixture 3 and the negative electrode mixture 7 is 30 μm or less, the electron conduction network path to the active material in the electrode is reduced, the output current is reduced, and when the thickness is 500 μm or more, the electrolyte layer As a result of the long ion conduction path from the electrode interface contacting 8, the internal resistance of the electrode increases and the output current decreases. Therefore, in order to increase the charge / discharge performance of the all-solid-state secondary battery, an optimum thickness exists as the thickness of the electrode.

Next, a configuration example of the current collector of the positive electrode (I) and the negative electrode (II) will be described. The configuration is shown in FIG. The positive electrode current collector 2 and the negative electrode current collector 6 used are electrically connected to the positive electrode lead plate 1 or the negative electrode lead plate 5, and the positive electrode current collector 2 or the negative electrode current collector 6 has electronic conductivity. A net material may be used.
Further, for example, by using a press-molded body plate having irregularities or a molded body plate by etching, a shape that serves as the positive electrode lead plate 1 or the negative electrode lead plate 5 and the current collector may be used. Reference numerals 403 and 404 each include a regulating portion 11 as a reinforcing body on the outer peripheral portion of the electrode. The reinforcing body described above can use an insulating material or a conductive material, and can also serve as the electrolyte layer 8.

  In addition, in the structure of positive electrode (I) and negative electrode (II), the kind of base material shown in FIG. 4 is different even if it is the same as that used in positive electrode (I) and negative electrode (II), respectively. Also good. In the present embodiment, an electrolyte layer 8 is provided between the positive electrode (I) and the negative electrode (II) so as to cover at least one entire electrode. In the present embodiment, the electrolyte layer 8 is formed as a sheet glass by press-molding a novel solid electrolyte glass powder and heating and compressing it.

Although it does not specifically limit as an average particle diameter of this novel solid electrolyte glass particle, It is preferable that it is about 1 micrometer-20 micrometers, and it is more preferable that it is about 1 micrometer-10 micrometers. The use of solid electrolyte particles of such a size improves the contact between the solid electrolyte glass particles when the electrode is finally heated and compressed to the softening temperature of the electrolyte glass constituting the all-solid lithium secondary battery element. In the inside, the bonding area between the electrode active material and the electrolyte glass particles can be increased, a sufficient migration path of lithium ions can be secured, and the characteristics of the battery element and the laminated secondary battery made using the same can be further improved. Can be improved.
Further, the average thickness of the electrolyte layer 8 is preferably about 10 μm to 500 μm, and more preferably about 30 μm to 300 μm.

As described above, in this embodiment, the battery element is configured with the electrolyte layer 8 covering the periphery of the positive electrode (I) and the negative electrode (II) described above. As a result, in the electrode prepared using the positive electrode mixture 3 and the negative electrode mixture 7 in which the electrode active material and the conductive material such as carbon are mixed, the electrode active material and the conductive material fall off from the electrode, and the electrolyte layer 8 Do not pollute the surrounding edge.
That is, the phenomenon of short-circuiting between the positive electrode (I) and the negative electrode (II) can be eliminated. The short circuit between the electrodes due to the desorption of the active material from the electrode occurs more frequently as the electrolyte layer of the battery element is thinner. As a result, in a laminated battery configured by using a plurality of unit cells composed of a thin electrode group and an electrolyte group, if there is even one defective battery element in the internal battery element, a laminated battery cannot be configured. Further, the effect of this embodiment can be obtained, which is preferable.

  In addition, the positive electrode current collector 2, the negative electrode current collector 6, the positive electrode lead plate 1, and the negative electrode lead plate 5 used in the present embodiment can be those having irregularities on the surface of the lead plate. By using this lead plate, it is possible to exhibit the function of providing the gaps filled with the positive electrode mixture 3 and the negative electrode mixture 7 described above in the concavo-convex portion. As a result, there is an advantage that the positive electrode lead plate 1 and the negative electrode lead plate 5 can omit the use of the positive electrode current collector 2 and the negative electrode current collector 6.

At this time, the cross-sectional shape of the concave and convex portions in the concaves and convexes is not particularly limited, and is round, elliptical, triangular, rectangular, square, rhombus-like quadrilateral, pentagonal, hexagonal, octagonal polygonal, irregular Any of a fixed form etc. is good. Further, two or more types of irregularities having different cross-sectional shapes may be mixed on the surfaces of the positive electrode lead plate 1 and the negative electrode lead plate 5.
The ratio of the area occupied by the concave portions in the positive electrode lead plate 1 and the negative electrode lead plate 5 is preferably about 25% to 90%, and more preferably about 50% to 85% in the plan view.

The average height of the convex portions of the positive electrode lead plate 1 and the negative electrode lead plate 5 is preferably about 50 μm to 400 μm, and more preferably about 100 μm to 200 μm.
By setting the ratios and dimensions of the concave portions and the convex portions within such ranges, the concave and convex portions can more reliably exhibit the function as the current collector.

Next, FIG. 5 shows an all-solid lithium secondary battery having a different structure and a structure in which the battery element is installed in the battery container 19. Here, the positive electrode (I) and the negative electrode (II) of the battery element are provided with a positive electrode terminal 12 and a negative electrode terminal 15 for charging / discharging through connection leads 13 and 16 having conductivity. The positive lead plate 1 and the negative lead plate 5 are connected.
Each of the positive electrode terminal 12 and the negative electrode terminal 15 is connected in advance through hermetic electrode terminals 14 and 17 installed in the battery container lid 20, while the battery container 19 is filled with an insulating fixing material. In addition, this is inserted, and the joint portion 21 of the battery container lid 20 and the battery container 19 is sealed with seam welding or a packing material. Therefore, the positive electrode lead plate 1 and the negative electrode lead plate 5 are configured to penetrate the fixing portion 18.

  The fixed portion 18 is also placed in contact with the regulating portion 11 provided around the positive electrode and the negative electrode, and has the same function as the regulating portion 11, and is a surface for charging / discharging the battery. It has the function of regulating (maintaining) the expansion and contraction in the direction. That is, the positive electrode (I) and the negative electrode (II) have a function of restricting the expansion in the plane direction {direction substantially perpendicular to the direction from the positive electrode (I) to the negative electrode (II)} This also restricts the expansion in the surface direction of the electrolyte layer 8 interposed between the positive electrode and the negative electrode, and acts to inhibit electronic bonding inhibition at the electrolyte / electrode bonding interface.

  In general, in a battery element, the crystal structure of the electrode active material is three-dimensionally deformed (stretched) with charge and discharge. Therefore, for example, in an all-solid-state lithium secondary battery using a conventional configuration in which the restriction portion 11 is not provided on the electrode and a conventionally used sulfide lithium ion conductor, the electrode activity generated when the battery is charged and discharged The crystal structure of the substance is three-dimensionally deformed (changed). On the other hand, the positive electrode (I) and the negative electrode (II) are greatly deformed (stretched) in the plane direction, not in the thickness direction.

As a result, the positive electrode (I) and the negative electrode (II) are formed to protrude from the electrolyte layer 8. Naturally, the electrolyte layer 8 existing between the positive electrode and the negative electrode is also stretched in the plane direction (or expanded and contracted during the reverse reaction). Along with this, in such a portion, due to the occurrence of electronic inhibition to the electrode active material or junction inhibition that cuts the ion conduction path, it becomes difficult for current to flow along with charging / discharging of the battery element.
That is, peeling occurs at the contact interface between the electrode active material and the electrolyte from the portion, and the electronic bonding or ion conduction path is destroyed. This phenomenon gradually progresses by repeatedly charging and discharging the secondary battery. As a result, in the secondary battery, the battery capacity gradually decreases, and finally it becomes difficult to charge and discharge the secondary battery. .

  On the other hand, the battery element of the present embodiment has a function of restricting the expansion in the surface direction of the positive electrode (I) and the negative electrode (II), and occurs in the surface direction of the electrolyte layer 8 accompanying therewith. A configuration in which the restriction portion 11 and the fixing portion 18 having a function of restricting enlargement are provided can be more preferably applied. Thereby, at the time of production of the secondary battery and at the time of charging / discharging, the shape of the secondary battery is maintained as close to the initial shape as possible, that is, the positive electrode (I) and the negative electrode (II), the surface direction of the electrolyte layer 8 The above-mentioned inconvenience can be prevented by restricting the expansion to the above. As a result, it is possible to prevent the battery capacity from being lowered even by the progress of charging / discharging cycles (multiple charging / discharging).

The regulation portion 11 is made of an inactive material that does not affect the battery reaction, both of the electron conductive material and the insulating material. By setting it as this structure, the short circuit between positive electrode (I) and negative electrode (II) can be prevented reliably.
Examples of the insulating material include various resin materials such as thermoplastic resin, thermosetting resin, and photocurable resin, various glass materials, and various ceramic materials. Moreover, you may comprise combining 1 type (s) or 2 or more types among a thermoplastic resin, a thermosetting resin, a photocurable resin, and low melting glass. However, as the material to be used, it is necessary to select a material that needs to withstand the temperature when heated and compressed to the softening temperature of the electrolyte glass of the all-solid lithium secondary battery element.
By using these materials, the restricting portion 11 can be formed more easily. Moreover, it is preferable also from the easy to obtain the control part 11 with high mechanical strength.

  Examples of the thermoplastic resin include polyolefin, ethylene vinyl acetate copolymer, polyamide, and hot melt resin. Examples of the thermosetting resin include epoxy resins, polyurethane resins, and phenol resins. Examples of the photocurable resin include epoxy resins, urethane acrylate resins, vinyl ether resins, and the like.

  Moreover, although the regulation part 11 changes a little depending on the constituent material, purpose, etc., it is preferable that the average thickness (especially the average thickness of the side surface) is about 30 μm to 500 μm, and about 50 μm to 300 μm. More preferably. By setting within this range, the positive electrode (I), the negative electrode (II), and the electrolyte layer 8 can be reliably prevented from expanding in the surface direction, and the function as the restricting portion 11 can be reliably exhibited.

  Next, the process of creating an all-solid lithium secondary battery using the members as described above will be described.

  A conventional process for producing an all-solid-state lithium secondary battery includes, for example, the current collector structure shown in the current collector structure 401 of FIG. 4 with the lower male mold 600 inserted using the mold in FIG. The positive electrode lead plate 1 and the negative electrode lead plate 5 side are inserted into the cylindrical hole 603 of the molding die 602 so as to contact the lower die. Thereafter, the positive electrode composite material 3 and the negative electrode composite material 7 are filled in the cylindrical hole 603, and the positive electrode composite material 3 and the negative electrode composite material 7 are planarized, and then the upper male mold 601 is inserted and preliminarily Press molded. This was taken out and used as a positive electrode and a negative electrode.

Subsequently, the electrolyte layer and the electrode layer were integrally molded using the mold shown in FIG.
For this purpose, first, using the mold shown in FIG. 7, (i): after inserting the electrolyte powder 705A into the cylindrical hole 703A and smoothing [in this state, the electrolyte layer (801 in FIG. 8) State.]
Next, (ii): as the upper male mold, the upper male mold 706A having a convex portion for forming the electrode filling space portion is inserted into the electrolyte layer, and pressurized with a weak force [in this state, the electrolyte layer Is in the state (802 in FIG. 8)].
Subsequently, (iii): The upper male mold 706A is pulled out, and the electrode (positive electrode or negative electrode) already prepared is inserted into the concave surface of the resulting electrolyte layer so that the electrode active material surface is in contact with the electrolyte layer. Then, the upper male mold 701A is preliminarily pressure-molded [in this state, the electrolyte layer and the electrode layer (positive electrode) are integrated into a state of 803 in FIG. 8].
Subsequently, the mold is turned upside down and reversed, and processing is performed in the same manner as in steps (iv) :( i) to (iii), so that the state of (804 in FIG. 8) is obtained, and finally (v ): Then, the battery element of the present invention is configured by setting the state (805 in FIG. 8).

In this step, both the positive electrode and the negative electrode are surrounded by the electrolyte layer, but an electrode on one side and the electrolyte layer may be integrated. In this structure, when these integrated molded products to be described later are further heat-compressed and integrated, they are used to produce a battery element in which lithium, indium or the like having low heat resistance as a negative electrode active material is pressed and pasted.
As described above, the pressure for pressure molding used in these steps is preferably 1 ton / cm ² or more, and more preferably 2 ton / cm ² . Thereby, while being able to compress suitably the positive electrode compound material 3 and the negative electrode compound material 7, the positive electrode compound material 3 and the negative electrode in the space | gap part with which the positive electrode collector 2 and the negative electrode collector 6 (refer FIG. 4) are equipped. The compound material 7 can be reliably filled, and further integration by heating and compression is further ensured.
Under the present circumstances, the various metal mold | die used for manufacture of an all-solid-state lithium secondary battery is not limited to metal, For example, resin and ceramics may be sufficient.

  Next, the manufacturing method for manufacturing the all solid lithium secondary battery of the present invention will be sequentially described in further detail using the flowchart of FIG.

<A> Electrode forming step 901
First, the positive electrode current collector 2 and the negative electrode current collector 6 necessary for electrode preparation shown in FIG. 4 are prepared in advance.

  (I) Electrode creation process: The positive electrode current collector 2 and the negative electrode current collector 6 are arranged so that the positive electrode lead plate 1 and the negative electrode lead plate 5 are in contact with the lower male mold 600 in the cylindrical hole 603 of FIG. The positive electrode mixture 3 and the negative electrode mixture 7 are filled. After the filled positive electrode mixture 3 and negative electrode mixture 7 are planarized, a positive electrode and a negative electrode are created by pressure molding using the upper male mold 601. By extracting this from the mold, the electrode of the battery for the present invention (FIG. 3-1) is created.

<B> Electrolyte integrated joining step 902
Next, a mold (see FIG. 7) having an inner diameter larger than the cylindrical hole 603 used for electrode preparation is prepared as a mold for forming the electrolyte layer, and the lower male mold 700A is placed in the cylindrical hole 703A of the mold. In a state in which is inserted, the electrolyte powder 705A is filled in the cylindrical hole 703A.
Next, in order to form an uneven portion capable of forming an electrode shape in the electrolyte layer in the cylindrical hole 703A, an upper male molding die 706A having a projection 707A serving as an electrode insertion portion is inserted, and this is preliminarily pressure molded. As a result, an electrolyte layer having a portion into which the electrode can be inserted is formed.
Thereafter, the upper male mold 706A is taken out, and the electrode (for example, positive electrode) created in the step <A> electrode forming process 901 is inserted into the electrode insertion portion formed in the electrolyte layer, so that the upper male mold without the protruding portion is inserted. By inserting 701A and performing pre-press molding, an electrolyte layer in which the periphery of the positive electrode is covered with an electrolyte layer and the electrode (positive electrode) can be integrated (803 in FIG. 8).

<C> Battery element creation step 903
Next, without removing the molded body in which the positive electrode and the electrolyte layer are integrated, the molding die (see FIG. 7) is turned upside down, and then the upper lower male molding die 700A is taken out once, and the inside of the cylindrical hole 703A is removed. An electrolyte having a portion into which an electrode (negative electrode) can be inserted by inserting an upper male mold 706A having a projection 707A capable of forming an electrode shape into the surface of the electrolyte layer and preliminarily press-molding it. Form a layer.
Subsequently, the upper male mold 706A is taken out, a terminal electrode (negative electrode) prepared in advance is inserted into this part, a lower male mold 700A having no protrusion is inserted, and pressure molding is performed at a predetermined pressure. A unit cell to be a single cell element (805 in FIG. 8) in which the periphery of the positive electrode layer and the negative electrode layer is covered with an electrolyte layer can be produced.

Molding in this step was performed while heating to a temperature range where the electrolyte softens. Therefore, the applied pressure may be about 1 ton / cm ² , and more preferably 2 ton / cm ² or more. As a result, the battery element is sufficiently compressed, and the periphery of the positive electrode (I) and the negative electrode (II) in the battery element can be completely covered with the electrolyte layer, thereby ensuring the bonding strength or interfacial bonding. .
As a result, it is possible to reliably prevent a short circuit between the positive electrode and the negative electrode in the produced battery element and to produce a battery with a constant battery performance.
Further, a mold release agent for improving the mold releasability of the battery element to be formed may be provided on the inner surface of the cylindrical hole 703A of the female mold for molding 702A used in these steps.

<D> Battery sealing step 904
This process will be described with reference to the battery element of FIG.
<C> The battery element obtained in the battery element creation step 903 is prepared with a mold that is larger than the mold shown in FIG.
Subsequently, after the inserted battery element is filled with a low melting point glass frit having a softening temperature of 350 ° C. or lower, the negative electrode terminal 4 is inserted, and the whole is pressurized so that the periphery between the electrode terminals of the battery element A battery element filled with a low melting point glass frit is prepared.

The battery element in this state is heated to a temperature at which the low melting point glass frit is softened and melted under pressure, and the whole battery element is hermetically sealed (seal portion 10). As the low melting point glass used here, one having a softening temperature in the range of 200 ° C. to 350 ° C. or less was selected.
As such a low melting glass, PbO—B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ based lead glass and other low melting glass not containing lead are also used as sealing materials in this softening temperature range. Is possible. However, if there is lead oxide, if this material is in electrical contact at the negative electrode interface, the reduction proceeds easily, and furthermore, they are included in the sulfide-based lithium ion conductor present inside the battery. In order to use the battery for a long period of time, it is necessary to use a lead-free low-melting glass composed of four components of V ₂ O ₅ , ZnO, BaO and TeO _2. Is around 320 ° C. and can be preferably used.

When this sealing material is used, the whole battery is heated to around 220 ° C. in this way, and the whole battery is compressed within 5 hours. Further, even if the battery sealing part is heated locally, Since it does not reach the temperature for crystallizing the internal sulfide-based lithium ion conductive solid electrolyte glass, it can be used.
Thereby, it becomes possible to eliminate the grain boundary between the electrolyte glass particles in the sulfide-based lithium ion conductive solid electrolyte glass layer existing inside. Furthermore, there is an effect of smoothing the interface bonding between the electrolyte particles and the electrode active material particles inside the electrode, the ion conduction path at the bonding interface is improved, and the effect of improving the battery output characteristics can be expected.

  In order to obtain such an effect, the reduced pressure heating state is maintained until a cured state of 60% or more is reached, and then the reduced pressure is released (pressure bonding may be performed if necessary) and sealing is performed. good. Moreover, in order to use the above-mentioned lead-free low-melting glass more suitably, the melting point may be lowered by adding a trace amount of lead material to these glasses. In order to adjust the thermal expansion of these materials, β-eucryptite, lead titanate, cordierite, etc. may be added to the glass frit used as a filler.

<E> Battery sealing step 905
This step is performed when a battery structure having the structure shown in FIG. 5 is prepared. Here, as the constituent material of the battery case 19 and the battery case lid 20, for example, various metal materials such as aluminum, copper, brass, stainless steel, various resin materials, various ceramic materials, various glass materials, composites made of metal and various resins. Although materials etc. are mentioned, it is needless to say that it is necessary to select a material that can withstand the softening temperature of the electrolyte glass.

  In this process, the positive electrode lead plate 1, the negative electrode lead plate 5, the positive electrode terminal 12, and the negative electrode terminal 15 of the battery element created in the <D> battery sealing step 904 are provided on the battery container lid 20. , 17 in advance. The product in this state is inserted into a pre-melted hot melt container, and the battery container 19 is cooled. Then, a packing is interposed at the junction 21 between the battery container lid 20 and the battery container 19 and pressed. Sealed by sealing.

  Hereinafter, in order to describe the all solid lithium ion secondary battery of the present invention in detail, a specific example will be used.

(Example 7)
Here, a battery configuration according to the present invention (see FIG. 2), that is, a battery element having a shape in which both electrodes are covered with an electrolyte layer between a pair of electrodes was prepared.
First, a positive electrode lead plate 1 or a negative electrode lead plate 5 and a positive electrode current collector 2 or a negative electrode current collector 6 are prepared as a current collector in the cylindrical hole 603 of FIG. The lead plate 5 is disposed so as to be in contact with the lower male mold 600 and filled with the positive electrode mixture 3 or the negative electrode mixture 7.
Subsequently, after the planarized positive electrode mixture 3 and negative electrode mixture 7 are planarized, an electrode (for example, a positive electrode) is formed by pressure molding using the upper male mold 601. By extracting this from the mold, the electrode of the battery for the present invention (see FIG. 3-1) is constructed.

Here, a ternary sulfide lithium ion conductive glass composed of lithium cobaltate as a positive electrode active material and Li ₂ S, SiS ₂ , Li ₃ PO ₄ as an electrolyte is used as a base material, and 5% of α-alumina is added thereto. A positive electrode mixture formed by mixing a new sulfide lithium ion conductor having a ionic conductivity of 3.2 × 10 ⁻³ S / cm ² into a glass powder and mixing them at a weight ratio of 7: 3. A positive electrode having a diameter of 16 mm, a thickness of about 250 μm was prepared.
The same electrolyte was used for the electrolyte layer, and the diameter was 18 mm and the thickness was 300 μm. Also, carbon powder (particle size, 5 μm) was used as the negative electrode active material, and a mixture was prepared by mixing it with the electrolyte at a ratio of 5: 5 by weight to prepare a negative electrode having a diameter of 16 mm, a thickness of 150 μm. . Since the net material as the current collector material used here is 100 μm and the lead plate is a titanium thin film having a thickness of 50 μm, the thickness of the lead plate is added as the total electrode thickness.

Next, a mold (see FIG. 7) having an inner diameter larger than the cylindrical hole 603 of the mold (see FIG. 6) used for electrode preparation is prepared as the electrode / electrolyte layer integration mold. In a state where the lower male mold 700A is inserted into the cylindrical hole 703A included in the mold, the cylindrical powder 705A is first filled with the electrolyte powder 705A.
Subsequently, an upper male molding die 706A having a projection 707A capable of forming an electrode shape is inserted into the cylindrical hole 703A, and an electrolyte layer having a portion into which the electrode can be inserted is preliminarily pressure-molded. Form.
Thereafter, the upper male mold 706A is taken out, the electrode (for example, positive electrode) already created is inserted into the electrode insertion portion formed in the electrolyte layer, and the upper male mold 701A having no protrusion is inserted, and pre-press molding is performed. By doing so, the electrolyte layer and the electrode (positive electrode) in which the periphery of the positive electrode is covered with the electrolyte layer are integrated (state 803 in FIG. 8).

Next, without removing the molded body in which the positive electrode and the electrolyte layer are integrated, the molding die (see FIG. 7) is turned upside down, and then the upper lower male molding die 700A is taken out once, and the inside of the cylindrical hole 703A is removed. An electrolyte layer having a portion into which an electrode (negative electrode) can be inserted is inserted by inserting an upper male mold 706A having a projection 707A capable of forming an electrode shape into the surface of the electrolyte layer and preliminarily press-molding it. Form.
Next, a terminal electrode (negative electrode) prepared in advance is inserted into this part, a lower male mold 700A is inserted, and the positive electrode layer is formed by pressure molding at a predetermined pressure (here, 3 tons / cm ² ). And the single cell element (state of 805 of FIG. 8) by which the circumference | surroundings of the negative electrode layer were covered with the electrolyte layer was created.

The battery element thus prepared is prepared with a mold larger than the mold shown in FIG. 7, and the positive electrode terminal 9 is installed in the mold so that the positive electrode side of the battery element comes into contact therewith. Insert into.
Subsequently, around the inserted battery element, a low melting point glass frit having a softening temperature of 400 ° C. or lower [low melting point glass composed of four components of V ₂ O ₅ —ZnO—BaO—TeO ₂ , YEV8-4103, Yamato Co., Ltd. The negative electrode terminal 4 is inserted and the whole is pressurized at a pressure of 2 ton / cm ² , so that the low melting point glass frit (seal part 10) is formed between the electrode terminals of the battery element. Can be obtained.
This was heated and compressed at about 310 ° C. for 1 hour as it was, then cooled, and an all solid lithium secondary battery having the structure shown in FIG. 2 was produced.

In order to investigate the characteristics of this battery, the electric ground was charged at a constant current of 500 μA / cm ^{2. After} the charging voltage reached 4.2 V, the charging was stopped when the current reached 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.
The results obtained are flat when the discharge voltage is about 4.0 V to 3.5 V, and a discharge capacity of about 115 mAh / gr is obtained at the end of the 3.5 V discharge. It was found to show a value close to the theoretical value of lithium acid.
Further, it has been found that the charge / discharge cycle performance maintains 90% or more of the initial capacity even after about 250 cycles. This is because the solid electrolyte layer has no single grain boundary, and the entire battery element is covered with electrolyte glass. As a result, the all-solid-state thin film battery exhibits excellent charge / discharge cycle characteristics. It is thought that the same characteristics were obtained.

(Comparative Experiment 1)
In order to examine the effect of Example 7, here, the same battery constituent materials were used, and first, a battery element (FIG. 8-805) in which the positive electrode terminal 9 and the negative electrode terminal 4 were not present was pressurized. Integrated molding. At that time, the pressure used was molded at a pressure of 4 tons / cm ² stronger than Example 7.
The positive electrode terminal 9 and the negative electrode terminal 4 are brought into contact with both ends of the battery element thus prepared, and the periphery thereof is insulatively bonded with an epoxy resin to prepare an all-solid lithium secondary battery by a conventional method, and charging / discharging of the battery The cycle characteristics were examined under the same conditions as in Example 7.
As a result, the initial charge / discharge capacity was the same as that of the battery of the present invention. However, with the progress of the charge / discharge cycle, the charge / discharge capacity of the battery prepared by the conventional method decreased for a while and decreased to about 65% of the initial capacity after 100 cycles.
This decrease was considered to have occurred because the grain boundary junction in the electrode layer inside the battery and the electrolyte grain interface in the electrode layer were destroyed along with the charge / discharge cycle, causing an increase in battery internal resistance.

(Example 8)
Here, instead of the electrolyte (α-Al ₂ O ₃ , Li ₂ S, SiS ₂ , Li ₃ PO ₄ ) used in Example 7 for the battery element, sulfide-based lithium ion containing 5% α-alumina An all-solid lithium secondary battery was fabricated in exactly the same manner as in Example 7, except that a novel crystalline sulfide-based lithium ion conductive solid electrolyte glass made of a conductor (Li ₂ S—GeS ₂ —P ₂ S ₅ ) was used. Created.

In order to investigate the characteristics of the battery thus prepared, the electric ground was charged with a constant current of 500 μA / cm ² , and after the charging voltage reached 4.2 V, the charging was stopped when the current became 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.

The obtained results are almost the same as in Example 7. The discharge voltage is flat when the voltage is about 4.0 V to 3.5 V, and a discharge capacity of about 113 mAh / gr is obtained at the end of 3.0 V discharge. These battery capacities were found to be batteries showing values close to the theoretical value of lithium cobalt oxide.
Further, it has been found that the charge / discharge cycle performance maintains 90% or more of the initial capacity even after about 250 cycles. This situation is shown in an all-solid-state thin film battery because the solid electrolyte layer is in a state without a single grain boundary, and as a result of the entire battery element being covered with electrolyte glass, It is thought that the same characteristics as the charge / discharge cycle characteristics have been given.

(Comparative experiment 2)
In order to examine the effect of Example 8, here, the same battery constituent materials were used, and first, a battery element (805 in FIG. 8) without positive electrode terminal 9 and negative electrode terminal 4 was pressurized. Integrated molding. At that time, the pressure used was molded at a pressure of 4 tons / cm ² stronger than Example 7.
The positive electrode terminal 9 and the negative electrode terminal 4 are brought into contact with both ends of the battery element thus prepared, and the periphery thereof is insulatively bonded with an epoxy resin to prepare an all-solid lithium secondary battery by a conventional method, and charging / discharging of the battery The cycle characteristics were examined under the same conditions as in Example 7.

As a result, the initial charge / discharge capacity was the same as that of the battery of the present invention. However, with the progress of the charge / discharge cycle, it has been found that the charge / discharge capacity of the battery produced by the conventional method decreases for a while and decreases to about 77% of the initial capacity after 100 cycles.
This decrease was considered to have occurred because the grain boundary junction in the electrode layer inside the battery and the electrolyte grain interface in the electrode layer were destroyed along with the charge / discharge cycle, causing an increase in battery internal resistance.

Example 9
Here, a novel sulfide-based lithium ion conductive solid electrolyte glass made of a sulfide-based lithium ion conductor (Li ₂ S—P ₂ S ₅ ) containing 5% α-alumina was used as the electrolyte of the battery element, An all solid lithium secondary battery was prepared in exactly the same manner.
In order to investigate the charge / discharge cycle characteristics of the battery thus prepared, the electric charge was charged with a constant current of 500 μA / cm ² , and when the charge voltage reached 4.2 V, the charge was stopped when the current reached 30 μA. Then, after a charge stop time of 30 minutes, discharge was started at the same current value.

The obtained results are almost the same as in Example 7. The discharge voltage is flat when the voltage is about 4.0 V to 3.5 V, and a discharge capacity of about 120 mAh / gr is obtained at the end of 3.0 V discharge. It has been found that these battery capacities are approximately 100% of the theoretical value of lithium cobalt oxide.
Further, it has been found that the charge / discharge cycle performance maintains 95% or more of the initial capacity even after about 270 cycles. This situation is shown in an all-solid-state thin film battery because the solid electrolyte layer is in a state without a single grain boundary, and as a result of the entire battery element being covered with electrolyte glass, It is thought that the same characteristics as the charge / discharge cycle characteristics have been given.

(Comparative Experiment 3)
In order to examine the effect of Example 9, here, the same battery constituent materials were used, and first, a battery element (805 in FIG. 8) without positive electrode terminal 9 and negative electrode terminal 4 was pressurized. Integrated molding. At that time, the pressure used was molded at a pressure of 4 tons / cm ² stronger than Example 7.
The positive electrode terminal 9 and the negative electrode terminal 4 are brought into contact with both ends of the battery element thus prepared, and the periphery thereof is insulatively bonded with an epoxy resin to prepare an all-solid lithium secondary battery by a conventional method, and charging / discharging of the battery The cycle characteristics were examined under the same conditions as in Example 7.

As a result, the initial charge / discharge capacity was the same as that of the battery of the present invention. However, with the progress of the charge / discharge cycle, it has been found that the charge / discharge capacity of the battery produced by the conventional method decreases for a while and decreases to about 75% of the initial capacity after 95 cycles.
This decrease was considered to have occurred because the grain boundary junction in the electrode layer inside the battery and the electrolyte grain interface in the electrode layer were destroyed along with the charge / discharge cycle, causing an increase in battery internal resistance.

(Example 10)
Here, instead of the electrolyte (α-Al ₂ O ₃ , Li ₂ S, SiS ₂ , Li ₃ PO ₄ ) used in Example 7 for the battery element, sulfide-based lithium ion containing 5% α-alumina An all-solid lithium secondary battery was prepared in exactly the same manner as in Example 7, except that a novel crystalline sulfide-based lithium ion conductive solid electrolyte glass made of a conductor (Li ₂ S—B ₂ S ₃ ) was used.
In order to investigate the characteristics of the battery thus prepared, the electric ground was charged with a constant current of 500 μA / cm ² , and after the charging voltage reached 4.2 V, the charging was stopped when the current became 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.

The obtained results are almost the same as in Example 7, and the discharge voltage is flat when the voltage is about 4.0 V to 3.5 V, and when the 3.0 V discharge is completed, a discharge capacity of about 108 mAh / gr is obtained. These battery capacities were found to be batteries showing values close to the theoretical value of lithium cobalt oxide.
Further, it has been found that the charge / discharge cycle performance maintains 92% or more of the initial capacity even after about 220 cycles. This situation is shown in an all-solid-state thin film battery because the solid electrolyte layer is in a state without a single grain boundary, and as a result of the entire battery element being covered with electrolyte glass, It is thought that the same characteristics as the charge / discharge cycle characteristics have been given.

(Comparative Experiment 4)
In order to examine the effect of Example 10, here, the same battery constituent material was used, and first, the battery element (FIG. 8-805) without the positive electrode terminal 9 and the negative electrode terminal 4 was pressurized. Integrated molding. At that time, the pressure used was molded at a pressure of 4 tons / cm ² stronger than Example 7.
The positive electrode terminal 9 and the negative electrode terminal 4 are brought into contact with both ends of the battery element thus prepared, and the periphery thereof is insulatively bonded with an epoxy resin to prepare an all-solid lithium secondary battery by a conventional method, and charging / discharging of the battery The cycle characteristics were examined under the same conditions as in Example 7.

As a result, the initial charge / discharge capacity was the same as that of the battery of the present invention. However, as the charge / discharge cycle progresses, it has been found that the charge / discharge capacity of the battery produced by the conventional method decreases for a while and decreases to about 70% of the initial capacity after 120 cycles.
This decrease was considered to have occurred because the grain boundary junction in the electrode layer inside the battery and the electrolyte grain interface in the electrode layer were destroyed along with the charge / discharge cycle, causing an increase in battery internal resistance.

(Example 11)
Here, the batteries prepared in Examples 7 to 10 were subjected to a continuous voltage application test of 4.2 V in a high-temperature bath at 60 ° C.
As a result, an internal short circuit occurred in all the batteries except for the batteries of Example 9 and Example 10, and the function as a battery was not exhibited.
As for this phenomenon, Si and Ge are contained in the solid lithium ion conductive electrolyte of the battery used in Example 7 and Example 8, and this is reduced when the battery is charged. It was thought that the electrolyte came to have.

Example 12
Here, a battery was prepared in exactly the same manner except that the negative electrode active material of the battery used in Example 7 was prepared using indium powder instead of carbon.
In order to investigate the characteristics of this battery, the electric ground was charged with a constant current of 500 μA / cm ^{2. After} the charging voltage reached 4.0 V, the charging was stopped when the current reached 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.

  The obtained results were flat when the discharge voltage was about 3.7 V to 3.0 V, and when the voltage reached 2.5 V, the discharge was terminated. As a result, a discharge capacity of about 117 mAh / gr was obtained. This battery capacity showed a value almost close to the theoretical value of lithium cobalt oxide. Further, it has been found that the charge / discharge cycle performance maintains 90% or more of the initial capacity even after about 150 cycles.

In this situation, the solid electrolyte layer is in a state without a single particle, and the entire battery element is covered with electrolyte glass. It is considered that the same characteristics as the discharge cycle characteristics have been given.
In addition, as a test of this battery, as a result of overcharging a voltage of 4.0 V in a high temperature layer of 60 ° C. for two consecutive months, no abnormality was found in the charge / discharge performance of the battery after the end. It was.

(Example 13)
Here, a battery was prepared in exactly the same manner except that the negative electrode active material of the battery used in Example 8 was prepared using indium powder instead of carbon.
In order to investigate the characteristics of this battery, the electric ground was charged with a constant current of 500 μA / cm ^{2. After} the charging voltage reached 4.0 V, the charging was stopped when the current reached 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.

The obtained results are flat when the discharge voltage is about 3.7 V to 3.0 V, and a discharge capacity of about 108 mAh / gr is obtained at the end of 2.5 V discharge. The value was close to the theoretical value of lithium acid.
Further, it was found that the charge / discharge cycle performance maintained 89% or more of the initial capacity even after about 150 cycles. This situation is shown in an all-solid-state thin film battery because the solid electrolyte layer is in a state without a single grain boundary, and as a result of the entire battery element being covered with electrolyte glass, It is thought that the same characteristics as the charge / discharge cycle characteristics have been given.
In addition, as a result of conducting an overcharge test for 4.0 months at a voltage of 4.0 V in a high temperature layer of 60 ° C., no abnormality was found in the charge / discharge performance of the battery after the end.

(Example 14)
Here, a battery was prepared in exactly the same manner except that the negative electrode active material used in Example 9 was prepared using indium powder instead of carbon.
In order to investigate the characteristics of this battery, the electric ground was charged with a constant current of 500 μA / cm ^{2. After} the charging voltage reached 4.0 V, the charging was stopped when the current reached 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.

The obtained results are flat when the discharge voltage is about 3.7 V to 3.0 V, and a discharge capacity of about 113 mAh / gr is obtained at the end of 2.5 V discharge. The value was close to the theoretical value of lithium. Further, it has been found that the charge / discharge cycle performance maintains 85% or more of the initial capacity even after about 160 cycles. This situation is shown in an all-solid-state thin film battery because the solid electrolyte layer is in a state without a single grain boundary, and as a result of the entire battery element being covered with electrolyte glass, It is thought that the same characteristics as the charge / discharge cycle characteristics have been given.
In addition, as a result of conducting an overcharge test for 4.0 months at a voltage of 4.0 V in a high temperature layer of 60 ° C., no abnormality was found in the charge / discharge performance of the battery after the end.

(Example 15)
Here, a battery was prepared in exactly the same manner except that Al powder (average particle size: 20 μm) was used instead of carbon as the negative electrode active material of the battery used in Example 9.
In order to investigate the characteristics of this battery, the electric ground was charged with a constant current of 500 μA / cm ^{2. After} the charging voltage reached 4.0 V, the charging was stopped when the current reached 30 μA. Discharge was started at the same current value after a stop time of 30 minutes.

The obtained results show that the discharge voltage is flat when the voltage is about 4.0 V to 3.5 V, and the discharge capacity of about 123 mAh / gr is obtained at the end of the 3.0 V discharge. It was found that the value was close to the theoretical value of lithium acid.
Further, it has been found that the charge / discharge cycle performance maintains 92% or more of the initial capacity even after about 210 cycles. This situation is shown in an all-solid-state thin film battery because the solid electrolyte layer is in a state without a single grain boundary, and as a result of the entire battery element being covered with electrolyte glass, It is thought that the same characteristics as the charge / discharge cycle characteristics have been given.
In addition, as a result of conducting an overcharge test for 4.0 months at a voltage of 4.0 V in a high temperature layer of 60 ° C., no abnormality was found in the charge / discharge performance of the battery after the end.

(Example 16)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced with exactly the same configuration except that the heating and compression conditions of the battery element used were variously changed.
In Example 9, the treatment was performed at 310 ° C. for 1 hour, but in this example, the heat compression temperature was set to 350 ° C., and the battery was produced within a treatment time of 30 minutes. Charging / discharging of the produced battery was performed in the same manner as in Example 9.
As a result, an initial discharge capacity of 27 mAh / gr was obtained. This was about 22% of the theoretical capacity, and this decrease in the discharge capacity was thought to be due to the fact that the electrolyte glass inside the battery crystallized, and as a result, the battery internal resistance increased, resulting in insufficient charging.

(Example 17)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced with exactly the same configuration except that the heating and compression conditions of the battery element used were variously changed.
In Example 9, treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was prepared by heating and compression treatment at a heating condition of 320 ° C. and a treatment time of 5.0.
Charging / discharging of the produced battery was performed in the same manner as in Example 9.
As a result, 113 mAh / gr was obtained as the initial discharge capacity. This was about 94% of the theoretical capacity, and it was found that the theoretical capacity was almost shown.

(Example 18)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced with exactly the same configuration except that the heating and compression conditions of the battery element used were variously changed.
In Example 9, treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was prepared by heating and compression treatment at a heating condition of 320 ° C. and a treatment time of 6.0.
Charging / discharging of the produced battery was performed in the same manner as in Example 9.
As a result, an expected discharge capacity of 89 mAh / gr was obtained. This was about 74% of the theoretical capacity, and it was found that the theoretical capacity was almost shown.

Example 19
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, the treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was produced by heating and compressing at a heating condition of 300 ° C. and a treatment time of 2 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 115 mAh / gr was obtained as the initial discharge capacity. This was about 96% of the theoretical capacity, and it was found that the theoretical capacity was almost shown.

(Example 20)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, the treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was prepared by heating and compressing at a heating condition of 300 ° C. for a treatment time of 5 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 110 mAh / gr was obtained as the initial discharge capacity. This was about 92% of the theoretical capacity, and it was found that almost the theoretical capacity was shown.

(Example 21)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, the treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was produced by heating and compressing at a heating condition of 300 ° C. and a treatment time of 6 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 98 mAh / gr was obtained as the initial discharge capacity. This was about 81% of the theoretical capacity, and it was found that the theoretical capacity was almost shown.

(Example 22)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was produced by heating and compressing at a heating condition of 250 ° C. and a treatment time of 5.0 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 113 mAh / gr was obtained as the initial discharge capacity. This was about 94% of the theoretical capacity, which was found to be close to the theoretical capacity.

(Example 23)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, the treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was prepared by heating and compressing at a heating condition of 220 ° C. and a treatment time of 5.0 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 119 mAh / gr was obtained as the initial discharge capacity. This was about 99% of the theoretical capacity, which was found to be the theoretical capacity.

(Example 24)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was prepared by heating and compression treatment at a heating condition of 200 ° C. and a treatment time of 4.0 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 121 mAh / gr was obtained as the initial discharge capacity. This was about 99% of the theoretical capacity, which was found to be the theoretical capacity.

(Example 25)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, the treatment was performed at 310 ° C. for 1 hour, but in this example, the heating condition was 200 ° C. and the treatment time was 6.0 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.
As a result, 117 mAh / gr was obtained as the initial discharge capacity. This was about 98% of the theoretical capacity, which was found to be the theoretical capacity.

(Example 26)
Here, in producing the battery of Example 9, an all-solid lithium secondary battery was produced in exactly the same configuration except that the battery element used was heated and various compression conditions were changed.
In Example 9, treatment was performed at 310 ° C. for 1 hour, but in this example, a battery was produced by heating and compression treatment at a heating condition of 180 ° C. and a treatment time of 4.0 hours.
The charge / discharge test for the prepared battery was performed in the same manner as in Example 9.

  As a result, 118 mAh / gr was obtained as the initial discharge capacity. This was found to represent about 98% of theoretical capacity. However, in this battery, unlike the batteries of Examples 16 to 24, a significant decrease in charge / discharge capacity was observed in charge / discharge cycle characteristics, and the capacity decreased to about 70% during 95 cycles of charge / discharge. .

The results obtained in Examples 16 to 26 are shown in FIG. In FIG. 11, the discharge capacity obtained in the initial charge / discharge cycle test of the prepared battery is expressed in mAh / gr depending on the processing time and the processing temperature condition.
As can be seen from this result, in the temperature range of about 200 ° C. to 300 ° C., which is the softening temperature range of the sulfide-based lithium ion conductive solid electrolyte glass, the discharge capacity change is It was not so large, and it was found that when the processing temperature was 300 ° C. or higher, the influence of the processing time appeared greatly. It was found that when the processing temperature is around 320 ° C., the discharge capacity is about 74% after 6 hours, and at 350 ° C., the discharge capacity is about 22% after 0.5 hours. These treatment times and treatment temperatures are thought to be due to the fact that the battery internal resistance increases due to the progress of crystallization of the solid electrolyte glass in the all-solid-state lithium secondary battery, so that the charging reaction is not sufficiently performed. It was. As a result, it has been found that the conditions for heating and compressing the entire battery are desirable in the battery preparation process if the temperature range is 200 ° C. to 320 ° C. and the processing time is within 5 hours.

(Example 27)
In the batteries prepared in Example 7 to Example 26, the structure shown in FIG. 2 was used by using a low melting point glass frit (YEV8-4103 manufactured by Yamato Electronics Co., Ltd.) having a softening temperature of 320 ° C. or less around the battery element. The all-solid-state lithium secondary battery of [V ₂ O ₅ —ZnO—BaO—TeO _{2 is used as} a low melting point glass, a low melting point glass consisting of four components of V ₂ O ₅ —ZnO—BaO—TeO ₂ , manufactured by Yamato Electronics Co., Ltd. All solid lithium secondary batteries were made in the same manner as in Example 7.
About the created all-solid-state lithium secondary battery, when the same charging / discharging test and continuous two-month overcharge test of Example 7 were done, it turned out that almost the same characteristic is shown.

(Example 28)
In the batteries prepared in Examples 7 to 26, the structure shown in FIG. 2 was used by using a low melting point glass frit (YEV8-4103 manufactured by Yamato Electronics Co., Ltd.) having a softening temperature of 320 ° C. or less around the battery element. The all-solid-state lithium secondary battery of [V ₂ O ₅ —ZnO—BaO—TeO _{2 is used as} a low melting point glass, a low melting point glass composed of four components, YEV8-3102, manufactured by Yamato Electronics Co., Ltd. All solid lithium secondary batteries were made in exactly the same manner as in Example 7.
About the created all-solid-state lithium secondary battery, when the same charging / discharging test as Example 7 and the continuous two-month overcharge test were done, it turned out that almost the same characteristic is shown.

(Example 29)
In the batteries prepared in Example 7 to Example 26, the structure shown in FIG. 2 was used by using a low melting point glass frit (YEV8-4103 manufactured by Yamato Electronics Co., Ltd.) having a softening temperature of 320 ° C. or less around the battery element. The all-solid-state lithium secondary battery of [V ₂ O ₅ —ZnO—BaO—TeO _{2 is used as} a low melting point glass, a low melting point glass composed of four components, YEV8-3302, manufactured by Yamato Electronics Co., Ltd. All solid lithium secondary batteries were made in the same manner as in Example 7.
About the created all-solid-state lithium secondary battery, when the same charging / discharging test as Example 7 and the continuous two-month overcharge test were done, it turned out that almost the same characteristic is shown.

(Example 30)
In the batteries prepared in Example 7 to Example 26, the structure shown in FIG. 2 was used by using a low melting point glass frit (YEV8-4103 manufactured by Yamato Electronics Co., Ltd.) having a softening temperature of 320 ° C. or less around the battery element. The all-solid-state lithium secondary battery of [V ₂ O ₅ —ZnO—BaO—TeO _{2 is used as} a low melting point glass, a low melting point glass composed of four components, YEV8-3118, manufactured by Yamato Electronics Co., Ltd. All solid lithium secondary batteries were made in exactly the same manner as in Example 7.
About the created all-solid-state lithium secondary battery, when the same charging / discharging test as Example 7 and the continuous two-month overcharge test were done, it turned out that almost the same characteristic is shown.

(Example 31)
In the batteries prepared in Examples 7 to 26, an all-solid lithium secondary battery having the structure shown in FIG. 2 was prepared using a low-melting glass frit having a softening temperature of 320 ° C. or less around the battery element. Here, as the low melting point glass, PbO—B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ based sealed lead glass for IC packages (glass code No. LS-0803) is used, and the heat compression treatment conditions are as follows: An all-solid lithium secondary battery was produced in the same manner as in Example 7 except that the temperature was 360 ° C. for 30 minutes.
The prepared all-solid lithium secondary battery was subjected to the same charge / discharge test and continuous two-month overcharge test as in Example 7. As a result, 99 mAh / gr was obtained as the initial discharge capacity, and discharge performance with a theoretical capacity of 83%. Gave. However, the result of the 60 ° C. overcharge test showed 66 mAh / gr, and it was found that the initial discharge capacity was 55% of the theoretical capacity. This is because the low melting point glass used as the battery seal material contains lead oxide that is susceptible to reduction electrochemically, and this is reduced, and the sealed portion becomes electronically conductive and is charged. It was estimated that the discharge characteristics deteriorated.

(Example 32)
In the batteries prepared in Examples 7 to 26, an all-solid lithium secondary battery having the structure shown in FIG. 2 was prepared using a low-melting glass frit having a softening temperature of 320 ° C. or less around the battery element. Here, as the low melting point glass, PbO—B ₂ O ₃ —SiO ₂ —Al ₂ O ₃ based sealed lead glass for IC packages (glass code No. LS-1101) is used, and the heat compression treatment conditions are as follows: An all-solid lithium secondary battery was produced in exactly the same manner as in Example 7 except that the temperature was 360 ° C. for 30 minutes. The prepared all-solid lithium secondary battery was subjected to the same charge / discharge test and continuous two-month overcharge test as in Example 7. As a result, 102 mAh / gr was obtained as the initial discharge capacity, and the discharge performance with a theoretical capacity of 85% was obtained. Gave. However, the result of the 60 ° C. overcharge test showed an initial discharge capacity of 68 mAh / gr, indicating 57% of the theoretical capacity. This is because the low melting point glass used as a battery sealing material contains lead oxide that is susceptible to reduction electrochemically, so that it is reduced and the sealing part has a slight electronic conductivity. It was estimated that the charge / discharge characteristics were deteriorated.

As described above, in order to seal the all solid lithium secondary battery, the low melting point glass material used does not contain lead that is susceptible to reduction electrochemically, and in the sulfide-based lithium ion conductive solid electrolyte. It has been found that it is necessary to select a material that does not easily react with the sulfur component.
As this condition, it has been found that the use of a low-melting glass composed of four components of V ₂ O ₅ —ZnO—BaO—TeO ₂ is suitable. In FIG. 12, the characteristics of various low melting point glasses are attached for reference.

  In summary, in the all-solid lithium secondary battery of the present invention using various sulfide-based lithium ion conductive solid electrolytes, the electrolyte existing inside the battery is heated to a temperature that softens and the whole is compressed. Thus, it was found that the battery performance, particularly the charge / discharge cycle life, is prevented from decreasing. As the heating temperature, a temperature range of 200 ° C. to 320 ° C. is desirable, and the treatment time needs to be shortened as the treatment temperature increases, but it can be said that the treatment is desirably performed within 2 hours. In addition, this heat compression process makes the bonding interface between the electrode active material particles and the electrolyte particles dense inside the electrode, and the interface bonding is improved. As a result, during the charging and discharging of the battery, the exchange of lithium ions becomes smooth and high. The possibility of rate charging / discharging is naturally an expected effect.

Further, in order to obtain a battery having a high operating voltage, it is desirable to use a reversible precipitation reaction of lithium ions or a reaction of carbon lithium as the negative electrode active material. When such a negative electrode active material is used, an electrolyte can be obtained. It has been found that if semiconductors such as Si and Ge are present, they are reduced during charging, and the electrolyte layer becomes electronically conductive particularly in a continuous overcharged state, which is not preferable. As a sulfide-based lithium ion conductive solid electrolyte, a Li ₂ S—B ₂ S ₃ or Li ₂ S—P ₂ S ₅ binary electrolyte is known as an electrolyte not containing Si or Ge. Alone, the ionic conductivity was as low as 2 × 10 ⁻⁴ S / cm ² , which was not practical. However, when α-alumina is mixed with this sulfide-based lithium ion conductor, and those obtained by vitrification thereof, it shows about 2 × 10 ⁻³ S / cm ^{2 and} can be a practical electrolyte. found. The α-alumina present in the electrolyte does not inhibit the battery reaction at the potential at which the redox reaction of lithium ions occurs. Even if Al is used as the negative electrode active material in the battery of Example 15, no charge / discharge performance is obtained. It has also been proved from the fact that it has no influence, and the application of this glassy electrolyte to a battery can provide a product having excellent battery performance and has a high industrial value.

Concept of a test cell for a conventional all-solid lithium secondary battery. The basic composition side view of the all-solid-state lithium secondary battery of this invention. FIG. 3 is a structure diagram of an electrode current collector used in the battery of the present invention. The electrode block diagram used by this invention. The other battery block diagram of this invention. Configuration surface of the electrode molding die. The metal mold drawing for battery element creation of the present invention. The creation flowchart of this invention battery element. The flowchart of a battery creation process. The figure which shows the influence on ionic conductivity (S / cm < ² >) by heating temperature and time. The figure which shows the influence on the initial stage discharge capacity (mAh / gr) by heat processing temperature and time. The figure which shows the various characteristics which various low melting glass has.

Explanation of symbols

  (I) ... positive electrode, (II) ... negative electrode, 1 ... positive electrode lead plate, 2 ... positive electrode current collector, 3 ... positive electrode mixture, 4 ... negative electrode terminal, 5 ... negative electrode lead plate, 6 ... negative electrode current collector , 7 ... Negative electrode mixture, 8 ... Electrolyte layer, 9 ... Positive electrode terminal, 10 ... Seal part.

Claims (13)

Including sulfide-based lithium ion conductive solid electrolyte,
The sulfide-based lithium ion conductive solid electrolyte glass, wherein the sulfide-based lithium ion conductive solid electrolyte contains α-alumina.   The sulfide-based lithium ion conductive solid electrolyte glass according to claim 1, wherein the sulfide-based lithium ion conductive solid electrolyte contains lithium sulfide-phosphorus sulfide or lithium sulfide-sulfuric boric acid. . As a fixed electrolyte, it has sulfide-based lithium ion conductive solid electrolyte glass,
The all-solid-state lithium secondary battery, wherein the sulfide-based lithium ion conductive solid electrolyte glass contains α-alumina.   The all-solid-state lithium secondary battery according to claim 3, wherein the sulfide-based lithium ion conductive solid electrolyte glass contains lithium sulfide-phosphorus sulfide or lithium sulfide-sulfur boric acid.   The all-solid lithium secondary battery element according to claim 3 or 4, wherein the all-solid lithium secondary battery element in which the solid electrolyte layer is interposed between a pair of electrodes composed of a positive electrode layer and a negative electrode layer is used. battery.   6. The all solid lithium secondary electronic device according to claim 5, wherein either the positive electrode layer or the negative electrode layer and the solid electrolyte layer are integrally molded. Secondary battery. a first step of heating and melting a mixture of sulfide-based lithium ion conductive solid electrolyte containing α-alumina;
A second step of quenching the heated and melted mixture;
The manufacturing method of the all-solid-state lithium secondary battery characterized by including the manufacturing process of the sulfide type lithium ion conductive solid electrolyte glass which has this.   Between a pair of electrodes consisting of a positive electrode layer and a negative electrode layer, a layer made of the electrolyte glass powder produced from the sulfide-based lithium ion conductive solid electrolyte glass and either the positive electrode layer or the negative electrode layer are heated and compressed. The manufacturing method of the all-solid-state lithium secondary battery of Claim 7 including the 3rd process of forming the all-solid-state lithium secondary battery element which integrated the electrode layer and the electrolyte layer by doing . The temperature condition for the heating is within the range of the glass softening temperature region of the sulfide-based lithium ion conductive solid electrolyte glass,
The method for producing an all-solid lithium secondary battery according to claim 8, wherein the heating is performed in a time range in which crystallization of the sulfide-based lithium ion conductive fixed electrolyte glass does not proceed. The glass softening temperature region is 200 ° C to 300 ° C,
The method for producing an all-solid-state lithium secondary battery according to claim 9, wherein the time range in which the crystallization does not proceed is within 5 hours.   11. The method according to claim 8, further comprising a fourth step of sealing at least a part of the all solid lithium secondary battery element with a low-melting glass having a softening temperature of 350 ° C. or lower. The manufacturing method of the all-solid-state lithium secondary battery of description. The method for producing an all-solid-state lithium secondary battery according to claim 11, wherein the low-melting glass is a glass composed of four components of V ₂ O ₅ , ZnO, BaO and TeO ₂ .   The said 1st process, the said 2nd process, the said 3rd process, and the said 4th process are continuously processed in the dry inert gas atmosphere, The Claim 11 or Claim 12 characterized by the above-mentioned. The manufacturing method of the all-solid-state lithium secondary battery of description.

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