JP7074362B2 - All-solid-state battery and negative electrode - Google Patents

Description

The present invention relates to an all-solid-state battery and a negative electrode.

Due to the recent improvement in the performance of portable electronic devices and hybrid vehicles, the batteries used therein (particularly secondary batteries such as lithium ion secondary batteries) are required to have higher capacities. However, with the current lithium secondary batteries, the capacity of the positive electrode has been delayed compared to that of the negative electrode, and even with the high-capacity Li (Ni, Mn, Co) O ₂ materials that have been actively researched and developed recently, 250 ~ It is about 300 mAh / g. Furthermore, as EV development begins in earnest, prices have more than doubled due to the lack of resources.

Sulfur has a high theoretical capacity of about 1670 mAh / g, and is one of the promising candidates for high-capacity electrode materials because of its abundant resources and low cost. However, elemental sulfur has low conductivity, and in a battery system using an organic electrolytic solution (lithium secondary battery, etc.), lithium polysulfide generated in the charge / discharge process elutes into the electrolytic solution and precipitates on the negative electrode, etc. However, there is a problem of causing a decrease in capacity.

In order to solve this, various attempts have been made to combine elemental sulfur with various organic materials such as resin and pitch to impart conductivity and suppress elution and diffusion of lithium polysulfide into the electrolytic solution. (For example, Patent Documents 1 to 3 and Non-Patent Documents 1 to 4 and the like). It has been reported that these sulfur-carbon complexes exhibit relatively high capacity and relatively good cycle characteristics.

Conventionally, these sulfur-carbon composites use a carbon material such as porous carbon or a solid organic substance such as polyacrylonitrile (PAN) or pitch as a raw material for a carbon source, and heat the raw material with elemental sulfur or a raw material containing sulfur. It has been produced by. In particular, an organic sulfur material produced using PAN as a raw material is listed as a promising candidate material as an electrode material with less cycle deterioration.

Further, in order to improve the safety of the battery, an all-solid-state battery using a sulfide solid electrolyte having lithium ion conductivity instead of a flammable organic electrolyte has been proposed. For example, an all-solid-state battery made of an organic sulfur material using PAN has been introduced (Non-Patent Document 1). Here, if it is an all-solid-state battery, it is expected that the problem of sulfur component elution will be solved.

When these sulfur-based positive electrode materials are used as a battery, unlike conventional oxide positive electrodes, the fact that the positive electrode does not contain lithium is a problem in assembling the battery. Therefore, it has been studied to add lithium to the sulfur-based positive electrode, to configure the negative electrode with lithium itself, or to have the silicon negative electrode hold lithium (Non-Patent Document 2).

When a sulfur-based positive electrode material is used, a negative electrode having a large capacity is required. Graphite has been used for the negative electrode so far, but when it is used for the negative electrode for a high-capacity positive electrode, a larger grain size (meshing: active material filling amount per unit area, mg / cm ² ) is required. This is not desirable because it is bulky and the energy density required for the battery is reduced.

When a high-capacity sulfur-based positive electrode material that does not have lithium is used as a battery, lithium foil or silicon, which is also a large-capacity negative electrode, is desired. Since silicon also does not have lithium, it is used by a method in which an electrode in which lithium is doped in advance, a silicon negative electrode and a lithium foil are bundled in a battery container, and the silicon and the positive electrode are doped with lithium by injecting an electrolytic solution. However, a method has been made in which lithium is electrochemically doped into silicon using an organic electrolytic solution, then the electrolytic solution is removed and incorporated into an all-solid-state battery, but there is a problem in that time and process cost are required. ..

For the electrodes of an all-solid-state battery, a slurry in which an active material, a solid electrolyte, and a conductive auxiliary agent are mixed, mixed with a rubber-based binder, etc., and mixed with a solvent such as heptane is mixed in a glove box as a base material such as aluminum foil or copper foil. The method of coating is done. These operations are performed in an expensive glove box environment because the solid electrolyte is deteriorated by moisture, and are restricted by equipment and operation. On the other hand, ordinary coated electrodes are manufactured using polyimide or the like as a binder when handling a large-capacity active material and do not contain a solid electrolyte, so that it is difficult to diffuse lithium ions when incorporated into an all-solid-state battery. It has been thought that there is. It would be a great manufacturing advantage if the electrodes could be manufactured by the usual method outside the glove box.

In an all-solid-state battery in which the electrolyte is solid, contact between the electrode and the solid electrolyte is important. In some cases, the method of depositing lithium on a solid electrolyte or powdered lithium could be used, but it was said that it was difficult to operate as a battery with a solid electrolyte and lithium foil.

In an all-solid-state battery using such a solid electrolyte, an electrode containing lithium in a positive electrode, using a lithium foil as a negative electrode, containing lithium in a silicon negative electrode by a simple method, or an electrode manufactured by a normal method is used as an all-solid-state battery. If it becomes possible to incorporate it into an all-solid-state lithium-ion secondary battery, it is possible to construct an all-solid-state lithium-ion secondary battery having a large capacity, high safety, and low cost.

Therefore, it has been reported that a high-capacity sulfur-based positive electrode material is produced by heating and refluxing alcohol with sulfur as a raw material (Non-Patent Document 4).

Further, it has been proposed to use a silicon negative electrode for an all-solid-state battery (Non-Patent Document 5).

However, the reality is that there is a demand for an all-solid-state battery with a larger discharge capacity and a negative electrode for that purpose.

Japanese Patent No. 5164286 Japanese Patent No. 5142162 International Publication No. 2010/0444437 Japanese Patent No. 6206900

J. E. Trevey et al., J. Electrochem. Soc., 159, A1019 (2012). Supervised by Tetsuo Sakai "Latest Technology Trends in Rare Metal Free Secondary Batteries" CMC Publishing (2013) X. Ji et al., Nat. Mater., 8, 500 (2009). T. Takeuchi et al., J. Electrochem. Soc., 164, A6288 (2017). N. Machida et al., Solid State Ionics, 176, 473-479 (2005).

In view of the above circumstances, an object of the present invention is to provide an all-solid-state battery having a large discharge capacity and a negative electrode for an all-solid-state battery.

As a result of diligent research to achieve the above object, the present inventors have found that a battery having a large discharge capacity can be obtained by constituting the positive electrode, the solid electrolyte, and the negative electrode with predetermined materials. The present inventors have further studied based on such findings, and have completed the present invention.

That is, the present invention provides the following all-solid-state battery and negative electrode.
Item 1.
An all-solid-state battery comprising an organic sulfur-based positive electrode, a sulfide-based solid electrolyte containing chlorine and / or bromine, and a negative electrode having a lithium layer.
Item 2.
Item 2. The all-solid-state battery according to Item 1, wherein the positive electrode contains a polyimide resin binder.
Item 3.
The negative electrode having the lithium layer includes the lithium layer and the negative electrode.
It is a laminate with a transition metal layer containing one or more selected from the group consisting of copper, titanium and stainless steel.
Item 2. The all-solid-state battery according to Item 1 or 2, wherein the lithium layer is provided between the sulfide-based solid electrolyte and the transition metal layer.
Item 4.
A negative electrode, which is obtained by applying molten lithium to a silicon particle-containing polyimide resin binder layer provided on one side of a base material.
Item 5.
An all-solid-state battery having an organic sulfur-based positive electrode containing a polyimide resin binder, a sulfide-based solid electrolyte containing chlorine and / or bromine, and a negative electrode according to Item 4.
Item 6.
Item 5. The all-solid-state battery according to Item 5, wherein the sulfide-based solid electrolyte contains a rubber-based binder.

According to the all-solid-state battery and the negative electrode according to the present invention, an all-solid-state battery having a large discharge capacity can be obtained.

The sectional view of the all-solid-state battery of Example 1. FIG. Charge / discharge curve of the all-solid-state battery of Example 1. The charge / discharge curve of the battery of Comparative Example 1. The sectional view of the all-solid-state battery of Example 2. FIG. Charge / discharge curve of the all-solid-state battery of Example 2. Charge / discharge curve of the all-solid-state battery of Example 3. Charge / discharge curve of the all-solid-state battery of Comparative Example 2. FIG. 6 is a schematic cross-sectional view of the all-solid-state battery of Example 4. The charge / discharge curve of the all-solid-state battery of Example 4. FIG. 6 is a schematic cross-sectional view of the all-solid-state battery of Example 5. The charge / discharge curve of the all-solid-state battery of Example 5. FIG. 6 is a schematic cross-sectional view of the all-solid-state battery of Example 6. The charge / discharge curve of the all-solid-state battery of Example 6. FIG. 6 is a schematic cross-sectional view of the all-solid-state battery of Example 7. The charge / discharge curve of the all-solid-state battery of Example 7. FIG. 6 is a schematic cross-sectional view of the all-solid-state battery of Example 8. The charge / discharge curve of the all-solid-state battery of Example 8. FIG. 6 is a schematic cross-sectional view of the all-solid-state battery of Example 9. Charge / discharge curve of the all-solid-state battery of Example 9.

(All solid state battery)
The all-solid-state battery of the present invention is characterized by comprising an organic sulfur-based positive electrode, a sulfide-based solid electrolyte containing chlorine and / or bromine, and a negative electrode having a lithium layer. In addition, in this specification, when a numerical value range is shown in the aspect of "A to B", it is defined as including the numerical values A and B at both ends thereof. Further, the all-solid-state battery of the present invention includes, and is not limited to, an all-solid-state lithium secondary battery, an all-solid-state lithium-sulfur secondary battery, and the like, depending on the material used.

Organic sulfur-based positive electrode The organic sulfur-based positive electrode can be obtained by using a material made of polyacrylonitrile, pitch, rubber, anthracene, amines, polyethylene glycol, carboxylic acid, linear alcohol and the like as raw materials. These can be used alone or in combination of two or more. In particular, it is preferable to construct an organic sulfur-based positive electrode using a composite (1-nonanol sulfide) obtained by reflux heat-treating a linear alcohol with sulfur as a material.

The material used for producing the above-mentioned organic sulfur-based positive electrode (hereinafter, also referred to as an organic sulfur-based positive electrode material) is preferably obtained by contacting the raw material with sulfur and heating at 290 to 310 ° C., and is in an amorphous state. It is preferable to have. Although it has properties as a polymer and its elemental composition is known, its structure and the like are unknown.

The organic sulfur-based positive electrode material is preferably a relatively low-density black solid having a density of 1.6 to 2.0 g / cm ³ (more preferably 1.7 to 1.9 g / cm ³ ). Unlike the oxide-based positive electrode material, since it does not substantially contain oxygen, it does not release oxygen and burn the organic electrolyte to cause a fire even when the temperature reaches 200 ° C. or higher in a charged state. In addition, it is difficult to decompose even at a high temperature of 300 ° C. and has high stability.

Further, by constructing an all-solid-state battery using a positive electrode using an organic sulfur-based positive electrode material, an all-solid-state battery having a sufficient discharge capacity can be obtained. Sufficient discharge capacity of the resulting all-solid-state battery when oxide-based positive electrode materials such as LiCo O ₂ , LiNi _0.333 Co _0.333 Mn _0.333 O ₂ , and LiNi _0.8 Co _0.15 Al _0.05 O ₂ are used in the production of the positive electrode. Cannot be secured.

On the other hand, since the organic sulfur-based positive electrode material has a low conductivity of ^10-8 to ^10-10 S / cm, it is also preferable to use acetylene black or the like as a conductive auxiliary agent to form a positive electrode.

Since these materials have a large capacity, the amount of lithium stored and released is relatively large, and therefore the amount of expansion and contraction is large. In a strong polyimide binder, the positive electrode is less likely to be broken as compared with a conventional binder such as PVDF, and high capacity characteristics can be used for a long period of time. Currently, in all-solid-state batteries, a large-area electrode is coated with a rubber-based binder and a solid electrolyte as a slurry using a low-polarity solvent that does not easily react with sulfide-based solid electrolytes (does not have oxygen or hydroxyl groups that strongly bind to solid electrolytes). It has been made. Since it is difficult to use a sulfur-based positive electrode material with severe expansion and contraction in such an electrode manufacturing method, if a positive electrode manufactured using a polyimide resin binder can be used, it will contribute to the industrialization of all-solid-state batteries. It becomes.

When an organic sulfur-based positive electrode material and silicon are used in a normal organic solvent-based electrolytic solution, lithium is about 5 times per unit weight in and out of the oxide-based positive electrode due to its large capacity, and the material particles expand. Shrinkage occurs with charge and discharge. Due to this volume change, the binder that holds the particles in the electrode is destroyed, and the contact between the electrode particles and the conductive auxiliary agent is hindered, so that the electrode characteristics are impaired. Therefore, it is preferable to use a polyimide resin having a strong bond so that the electrode is not broken as a binder.

As the polyimide resin binder, a known polyimide resin binder used for manufacturing a secondary battery including an all-solid-state battery can be widely used.

Specific examples include Kapton H (registered trademark) of DuPont, Skybond (registered trademark) and Dreambond (registered trademark) of commercial IST, as represented by the following general formula (I). Of course, it is not limited to these. Of the diamines and acid anhydrides that are the constituent elements of polyimide, which will be described later, polyamics, which are polyimide precursors, are combined by combining molecules that do not have polar groups, such as -OH and -NH, that react with solid electrolytes after being polyimideized. An acid can be formed, and such a polyimide-based resin binder can also be preferably used. These can be used alone or in combination of two or more.

In the production of the above-mentioned Kapton H (registered trademark), a known method can be widely adopted, and for example, it can be produced as follows. The 4,4'-Diaminodiphenyl Ether represented by the following general formula (II) and the 1,2,4,5-Benzenetetracarboxylic Dianhydride represented by the following general formula (III) are weighed at a molar ratio of 1: 1 and 1 each. -Dissolve in an organic solvent such as Methyl-2-pyrrolidone and then mix to create a (-CO-NH-) polyamic acid in which the amino group and one of the two carboxyl groups form a bond. In this state, it is a viscous solution and gives a preferable viscosity to the electrode coating. A polyamic acid (by mass of raw material) of 10 to 20% by mass and acetylene black as a conductive auxiliary agent are mixed at 75 to 85% by mass of the electrode material at 1 to 10% by mass, and coated on aluminum foil for the positive electrode and copper foil for the negative electrode. After drying, when the aluminum foil is fired in an inert gas atmosphere and the copper foil is fired in a hydrogen atmosphere at 250 to 300 ° C. for 30 minutes to 2 hours, water is desorbed from the polyamic acid and two adjacent carboxyl groups are bonded to the amino group. By forming an imide bond (-CO-N-CO-), it changes to polyimide, and a polyimide coated electrode can be manufactured.

The content of the polyimide resin binder is preferably, for example, 10 to 20 parts by mass per 100 parts by mass of the positive electrode. By having such a configuration, an all-solid-state battery having good charge / discharge characteristics can be obtained.

The thickness of the positive electrode is preferably 5 μm or more, and more preferably 10 μm or more in order to increase the basis weight. On the other hand, in order to ensure good contact with the solid electrolyte, the thickness of the positive electrode is preferably 20 μm or less, and more preferably 15 μm or less.

Solid sulfide electrolyte The solid sulfide electrolyte is not particularly limited as long as it is a sulfide solid electrolyte containing chlorine and / or bromine, and Li ₆ PS ₅ Cl, Li ₆ PS ₅ Br, etc. can be used. be. These can be used alone or in combination of two or more. When an all-solid-state battery is manufactured using a sulfide solid electrolyte containing neither chlorine nor bromine, an interface that hinders charging / discharging at the electrode may be formed depending on the material of the negative electrode described later. Above all, it is preferable to use a sulfide solid electrolyte having an Argyrodite type structure containing chlorine and / or bromine because of its high conductivity and high resistance to lithium metal.

Further, among the above-exemplified sulfide solid electrolytes containing chlorine and / or bromine (hereinafter, also simply referred to as solid electrolytes), the conductivity is relatively good, the amount of rare elements used is relatively small, and synthesis is performed. It is particularly preferable to use either or both of Li ₆ PS ₅ Cl and Li ₆ PS ₅ Br because of the ease of use. In addition, Li ₆ PS ₅ Cl and Li ₆ PS ₅ Br show stable operation on the lithium foil when the lithium foil is used in the negative electrode described later, so that it is possible to perform charge / discharge with particularly high sustainability.

The solid electrolyte disappears at grain boundaries at a pressure of 280 to 320 MPa and can exhibit high conductivity. The electrolyte in the laboratory is 90 to 110 mg in a 10 mmΦ metal tube or polyethylene terephthalate tube pressed with a die at a pressure of 130 to 150 MPa, with a positive electrode on one side and a negative electrode on the other side at 290 to 310 MPa (10 mmΦ). It is possible to construct a battery by crimping with a pressure of 2t).

It is preferable that the solid electrolyte is made into a sheet by coating or thinned by coating the solid electrolyte on the electrode. By performing the coating, it is possible to maintain a good balance between the weight of the battery and the amount of the electrode active material. It is preferable to prepare a slurry by mixing either or both of Li ₆ PS ₅ Cl and Li ₆ PS ₅ Br with 100 mg heptane in a mortar and adding a solution in which 3 mg of a rubber binder (MP-10) is dissolved in heptane. .. By applying this slurry to an electrode prepared by using an organosulfur-based positive electrode material and polyimide as a binder, which will be described later, an electrode-electrolyte thin layer can be produced.

The solid electrolyte is solid but can conduct only lithium ions between a negative electrode having a low potential and a positive electrode having a high potential. Since the sulfide-based solid electrolyte does not form a good interface with the generally used oxide-based positive electrode, it is preferable to apply various coatings such as LiNbO ₃ to the positive electrode material particles, but the organic sulfur-based positive electrode material is used. Can perform smooth charging and discharging without any special coating.

Further, the solid electrolyte portion substantially composed of the solid electrolyte may contain a binder in addition to the solid electrolyte. As the binder used here, a binder known as a binder used for producing a solid electrolyte of an all-solid-state battery can be widely used. Specific examples thereof include rubber-based binders, polytetrafluoroethylene, polyvinylidene difluoride and the like. These can be used alone or in combination of two or more. However, from the viewpoint of durability during use, it is preferable to use a rubber-based binder. As such a rubber-based binder, a known rubber-based binder can be widely adopted.

At this time, the blending amount of the binder is preferably 1 to 3 parts by mass in terms of the solid content of the binder per 100 parts by mass of the solid electrolyte portion so as not to interfere with the ion conduction.

The thickness of the solid electrolyte portion substantially composed of the solid electrolyte is preferably 0.04 to 0.3 mm, preferably 0.05 to 0.1 mm, in order to reduce the electric resistance of the battery. More preferred.

Negative electrode 1 (lithium foil type or lithium coating type on transition metal layer)
The all-solid-state battery of the present invention includes a negative electrode 1 having a lithium layer. The purity of lithium constituting the lithium layer is preferably 99% by mass or more. Examples of the impurities include, but are not limited to, Na, K, Al, Ca, Fe, Si, N and the like. The upper limit of the lithium purity is not particularly limited, and may be, for example, 100% by mass.

The thickness of the lithium layer is preferably 0.005 mm or more, and more preferably 0.01 mm or more, because it is easy to handle in manufacturing. On the other hand, the thickness of the lithium layer is preferably 0.1 mm or less, and more preferably 0.05 mm or less, for the reason of preventing a short circuit due to penetration during compression.

The method for forming the lithium layer can be formed by a known method, and is not particularly limited. Specifically, a lithium foil may be used, and the lithium foil itself may be configured as a lithium layer, or the lithium layer may be formed by a method such as applying molten lithium to a transition metal layer described later.

Further, the negative electrode 1 in the all-solid-state battery of the present invention is preferably a laminate of the above-mentioned lithium layer and a transition metal layer having higher conductivity. Here, the lithium foil is preferably provided between the sulfide-based solid electrolyte and the transition metal layer. The metal contained in the transition metal layer is not particularly limited as long as it is a metal that is difficult to alloy with lithium, and is preferably one or more selected from the group consisting of, for example, copper, titanium, and stainless steel. Of course, it is not limited to these.

One or more metals selected from the group consisting of copper, titanium and stainless steel contained in the transition metal layer are preferably contained in, for example, 99% by mass or more in the transition metal layer. In the present specification, when the transition metal layer contains 99% by mass or more of stainless steel, the transition metal layer contains 99% by mass or more of the components constituting the stainless steel (in other words, impurities described later are contained. It is defined as less than 1% by weight in the transition metal layer). Examples of impurities include, for example, Ag, Sn, and the like, and of course, the impurities are not limited thereto. The upper limit of the purity of copper is not particularly limited, and may be, for example, 100% by mass.

The thickness of the transition metal layer is preferably 0.005 mm or more, more preferably 0.01 mm or more, in order to withstand the deformation stress associated with charging and discharging. On the other hand, considering the energy per weight, it is preferably 0.03 mm or less, and more preferably 0.02 mm or less.

As a method for forming the transition metal layer, a known method can be widely adopted, and there is no particular limitation. Specifically, a method of laminating transition metal foils can be mentioned.

Here, even if nickel and / or indium are used as the transition metal contained in the transition metal layer in addition to those described above, it is possible to obtain an all-solid-state battery having a constant discharge capacity.

Further, it is considered that an all-solid-state battery having a constant discharge capacity can be obtained even if a carbon layer is used instead of the transition metal layer. However, even if the organic sulfur-based positive electrode material has a large discharge capacity, if the transition metal layer is used for the support of the lithium layer, there is an advantage that the negative electrode can be configured in a bulky manner. It is preferable to use a metal layer.

(Negative electrode 2 and all-solid-state battery using the negative electrode)
Negative electrode 2 (lithium coating type on resin binder layer)
Further, the negative electrode 2 of the present invention is characterized in that it is obtained by applying molten lithium to a silicon particle-containing polyimide resin binder layer provided on one side of a base material.

As the base material, a known base material used for the negative electrode of the secondary battery can be widely used. Specifically, copper, stainless steel, titanium, nickel and the like can be used. Above all, it is preferable to use copper in consideration of ease of handling and cost. As the material of the base material, one of the above-mentioned metals may be used alone, or an alloy composed of two or more kinds of metals may be used.

The thickness of the base material is preferably 0.005 to 0.02 mm in order to reduce the weight and withstand the deformation stress associated with charging and discharging.

The silicon particle-containing polyimide resin binder layer can be obtained by using a polyimide resin as a binder and adhering a material in which silicon particles are substantially uniformly dispersed to one side of a base material. Here, the content ratio of the silicon particles contained in the polyimide resin binder layer containing silicon particles to the polyimide resin binder is the mass ratio (silicon particles): (polyimide resin binder in terms of solid component) = 7: 1. ~ 4: 1 is preferable. By blending in such a ratio, it is possible to prevent the electrode from being destroyed by the expanding active material.

As the polyimide resin binder, the same ones as those described above can be used.

The particle size of the silicon particles is preferably 0.03 to 5 micrometers, more preferably 0.05 to 1 micrometer. By setting this numerical range, it is possible to prevent the electrode from being destroyed due to expansion. The particle size of the silicon particles can be obtained by analyzing the half width of the peak of XRD.

The silicon particle-containing polyimide resin binder layer may further contain a conductive auxiliary agent such as acetylene black. As conductive aids, in addition to acetylene black, vapor phase growth carbon fiber (specific products include vapor phase method carbon fiber VGCF (registered trademark); Vapor Grown Carbon Fiber of Showa Denko Co., Ltd.) and multi-walled. Examples thereof include carbon nanotubes, nano-sized carbon (specific products include Timcal's carbon-based conductive auxiliary agent SuperP (registered trademark)), carbon nanofibers, and graphene. These can be used alone or in combination of two or more.

The content of the conductive auxiliary agent in the silicon particle-containing polyimide resin binder layer is 2 to 8% by mass in 100% by mass of the silicon particle-containing polyimide resin binder layer in consideration of ensuring conductivity and ionic conductivity. It is preferable to do so.

As a method for providing the silicon particle-containing polyimide resin binder layer on the substrate, a composition in which silicon particles and, if necessary, acetylene black are appropriately dispersed in the polyimide resin binder described above is used as a base. It can be obtained by coating the material.

Since silicon has a larger capacity than the above-mentioned sulfur-based positive electrode material, the amount of lithium stored and released is relatively large, and therefore the amount of expansion and contraction is large. Since the positive electrode itself is destroyed in the conventional binder such as PVDF, the high capacity characteristic of the strong polyimide resin binder has made it possible to use it for a long period of time. Currently, in all-solid-state batteries, a large-area electrode is coated with a rubber-based binder and a solid electrolyte as a slurry using a low-polarity solvent that does not easily react with sulfide-based solid electrolytes (does not have oxygen or hydroxyl groups that strongly bind to solid electrolytes). It has been made. In such an electrode manufacturing method, it is difficult to use a sulfur-based positive electrode material positive electrode or a silicon negative electrode that expands and contracts rapidly. Therefore, if an electrode manufactured by a conventional method using a polyimide resin binder can be used, it is an all-solid-state battery. It will contribute to the industrialization of batteries.

The thickness of the silicon particle-containing polyimide resin binder layer is preferably 0.005 mm or more, and more preferably 0.01 mm or more in consideration of increasing the capacity of the battery. Further, in consideration of contact with the solid electrolyte, the thickness of the silicon particle-containing polyimide resin binder layer is preferably 0.03 mm or less, and more preferably 0.02 mm or less.

The negative electrode 2 of the present invention is obtained by applying molten lithium to the above-mentioned silicon particle-containing polyimide resin binder layer. The melting temperature is preferably 185 to 220 ° C because the melting point of lithium is 180.5 ° C.

Silicon has the drawback that the received lithium cannot be used effectively. Only 70% of the lithium received at the time of initial discharge can be taken out by charging, and since 70% of the lithium is exchanged with the positive electrode, 30% of the lithium that can no longer be used is called irreversible capacity. The method of eliminating the irreversible capacity of silicon in advance is called lithium pre-doping, in which lithium is electrochemically reacted in the electrolytic solution and the lithium used for the exchange between the irreversible reaction lithium and sulfur is stored in advance. The method is done. Mass production is difficult in the battery industry because it requires time, effort and equipment. The negative electrode 2 of the present invention achieves lithium pre-doping by adopting a configuration in which molten lithium is applied to a silicon particle-containing polyimide resin binder layer.

By bringing molten lithium into contact with the silicon particle-containing polyimide resin binder layer, the silicon particles of the silicon polyimide electrode can be changed into silicon-lithium alloy particles. Unlike the powder mixture electrode, the mass per unit area is small and the area can be increased, and this can be used to construct an all-solid-state battery together with an organic sulfur-based positive electrode material in an all-solid-state battery.

The amount of molten lithium applied is preferably 0.2 mg / cm ² to 1.2 mg / cm ² in consideration of increasing the basis weight of the battery and the balance between the irreversible capacity removal and the positive electrode capacity.

After coating, the molten lithium may form an alloy with the silicon particles in the silicon particle-containing polyimide resin binder layer, and the lithium layer may not be further formed on the silicon particle-containing polyimide resin binder layer. On the other hand, when a sufficient amount of molten lithium is applied, the surplus lithium that does not form an alloy with the silicon particles forms a lithium layer on the silicon particle-containing polyimide resin binder layer. The amount of the lithium layer is preferably 0.03 mg / cm ² to 0.5 mg / cm ² , preferably 0.06 mg / cm ² to 0.36, in consideration of using this lithium to eliminate the irreversible capacity of the positive electrode. More preferably, it is mg / cm ² .

Electrodes made using polyimide as a binder do not have particles in close contact with a solid electrolyte having a relatively large amount ratio, unlike a mixture electrode. However, the ions are transferred through oxygen and nitrogen contained in the polymer chain of the polyimide, or the electrolyte particles are pushed into the gaps between the electrodes due to the softness of the sulfide-based solid electrolyte. Conduction is possible.

Positive electrode and all-solid-state battery It is also preferable to use an all-solid-state battery in which the above-mentioned positive electrode is combined with the negative electrode of the present invention (the above-mentioned negative electrode 1 or 2).

As the solid electrolyte used here, the above-mentioned sulfide-based solid electrolyte containing chlorine and / or bromine can be used. Among them, those containing a rubber-based binder are particularly preferable. By using a rubber-based binder, surface deterioration of the solid electrolyte can be prevented.

The rubber-based binder used can be a known rubber-based binder used for the solid electrolyte of the secondary battery, and is not particularly limited. Specifically, MP-10, isoprene rubber, styrene-butadiene rubber, nitrile rubber and the like can be used. These can be used alone or in combination of two or more.

At this time, the blending amount of the binder is 1 to 5 parts by mass in terms of the solid content of the binder per 100 parts by mass of the solid electrolyte part because the resistance increase due to the addition is suppressed while maintaining the structure of the electrolyte layer as a sheet. Is preferable.

The thickness of the solid electrolyte portion substantially composed of the solid electrolyte is preferably 0.04 to 0.15 mm, more preferably 0.05 to 0.1 mm, from the viewpoint of ease of handling and reduction of resistance. preferable.

Although the embodiments of the present invention have been described above, the present invention is not limited to these examples, and it is needless to say that the present invention can be implemented in various forms without departing from the gist of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

(Example 1) 1-nonanol sulfide / Li ₆ PS ₅ Cl / InLi alloy negative electrode all-solid-state lithium secondary battery
Sulfur (Hosoi Kagaku 99.9%) 42.35 g, acetylene black (Denka black) 0.65 g, 1-Nonanol (1-Nonanol, Sigma-Aldrich 98%) 1.30 g were placed in a quartz tanman tube (inner diameter 80 mm, length 300 mm). After that, it was sealed with a silicone rubber stopper equipped with a thermocouple and a gas outlet / inlet, and nitrogen gas was supplied through a silicone tube to create a nitrogen atmosphere inside. The sample temperature was kept at 300 ° C in an electric furnace at 400 ° C, 2 ml of 1-nonanol was added every hour, a total of 10 ml was added, and heat treatment was performed for 4 hours. The crude product was pulverized and heated to 300 ° C. under a nitrogen stream to remove unreacted sulfur for 4 hours to give 4.75 g of 1-nonanol sulfide as a black powder.

Since solid electrolytes have high hygroscopicity, all work dealing with them was carried out in an argon atmosphere unless otherwise specified. The solid electrolyte Li ₆ PS ₅ Cl is LiCl (Wako, 99%) 0.638 g, lithium sulfide (Li ₂ S, Mitsuwa Kagaku 99.9%) 1.714 g, diphosphorus sulfide (P ₂ S ₅ , Sigma Aldrich, 99%). ) 1.658 g was placed in a zirconia pot and mixed with an experimental vibrating cup mill (MC-4A) manufactured by Ito Seisakusho for 30 minutes. The mixed powder was press-molded with a force of 1 ton using a 15 mmΦ carbon die to prepare pellets. The pellets were placed in a gold crucible, heated to 550 ° C. in a quartz test tube under vacuum, and calcined for 2 hours. The resulting product was ground in a mortar and used as a standard solid electrolyte. This solid electrolyte was measured by XRD (RINT TTR-III; Rigaku) to confirm that it was 92% by weight Li ₆ PS ₅ Cl with 8% by weight of lithium sulfide remaining. Conductivity was measured on pellets compressed (29MPa) of about 100mg of solid electrolyte powder with a 10.1mmΦ die, and 2.2 × 10 which is nearly 10 times that of 75Li ₂ S-25P ₂ S ₅ which has been generally used so far. It was confirmed that the material had a conductivity of ^-3 S / cm.

A positive electrode mixture was prepared by mixing 1-nonanol sulfide (39 mg), a solid electrolyte (57 mg), and acetylene black (6 mg). 77 mg of solid electrolyte was placed in a 10.1 mmΦ pet tube and compressed with a stainless die with a force of 1 ton to create a solid electrolyte disk in the PET tube. 10 mg of the positive electrode mixture was put on one side of the solid electrolyte disk and pressed with a force of 2.5 tons. On the other side of the solid electrolyte disk, indium foil (Niraco 99.99%, 0.05mmt, 10mmΦ), lithium foil (Honjo Metal 0.2mmt, 9mmΦ), indium foil (Niraco 99.99%, 0.2mmt, 8mmΦ), 1 ton of force was applied in this order and compressed to prepare a 1-nonanol sulfide / solid electrolyte / LiIn battery. The schematic cross-sectional view of the battery of Example 1 is as shown in FIG. This battery was charged and discharged in the range of 2.4-0.4V, starting from discharging and fixing at a current of 0.05mA. As shown in FIG. 2, in the initial discharge, sulfur of 1-nonanol sulfide was reduced, lithium ions were occluded, and the capacity was 970 mAh / g. Oxidation of sulfur occurred by charging, lithium ions were extracted from 1-nonanol sulfide, and reduction of sulfur occurred by discharging again, showing a capacity of 691 mAh / g. Sulfur-based positive electrode materials generally contain an irreversible capacity (about 280 mAh / g) in which the second discharge capacity is close to the reversible capacity and the first discharge exceeds the reversible capacity. Since it is generally known that the indium-lithium alloy negative electrode operates satisfactorily, it was found that the 1-nonanol sulfide positive electrode is a material exhibiting a high capacity of 691 mAh / g.

(Comparative Example 1) 1-nonanol sulfide / 1MLiPF ₆ + EC / DMC (3: 7) / Li lithium secondary battery
For comparison with the all-solid-state battery, 1-nonanol sulfide was incorporated into a battery using a general organic electrolyte and compared.

6.1 mg of 1-nonanol sulfide was mixed with 5.0 mg of acetylene black, and 0.5 mg of PTFE was added to prepare a positive electrode mixture. 2 drops of Kishida Chemical mixed electrolyte 1MLiPF6 + EC / DMC (3: 7) dropped on the positive electrode mixture, 2 polypropylene separators 21mmΦ soaked in the electrolyte, Watman glass filter 15mmΦ, lithium foil (Honjo Metal) The battery was constructed by mounting 0.2mmt) 15mmΦ made by Japan. It was cycled for the first time from discharge with a current of 0.1 mA in the range of 3-1 V. As shown in FIG. 3, the second discharge capacity was 467 mAh / g. From this, it was found that the all-solid-state battery had a discharge capacity higher than that of a normal liquid battery.

(Example 2) 1-nonanol sulfide / Li ₆ PS ₅ Cl / Li Negative electrode All-solid-state lithium secondary battery
A positive electrode mixture was prepared by mixing 1-nonanol sulfide (39 mg), a solid electrolyte (57 mg), and acetylene black (6 mg). 89.5 mg of solid electrolyte was placed in a 10.1 mmΦ pet tube and compressed with a stainless die with a force of 1 ton to create a solid electrolyte disk in the PET tube. 8.2 mg of the positive electrode mixture was put on one side of the solid electrolyte disk and pressed with a force of 2.5 tons. A lithium foil (0.2 mmt, 9 mmΦ made by Honjo Metal) was attached to the other surface of the solid electrolyte disk and compressed by applying a force of 1 ton to prepare a 1-nonanol sulfide / solid electrolyte / Li battery. A schematic cross-sectional view of the battery of the second embodiment is as shown in FIG. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 5, in the initial discharge, sulfur of 1-nonanol sulfide was reduced, lithium ions were occluded, and the capacity was 977 mAh / g. The discharge capacity of the second cycle was 646 mAh / g, and it was maintained at 413 mAh / g even after 10 cycles. When metallic lithium is used as the negative electrode, in an all-solid-state battery, needle-shaped lithium dendrites come into contact with the positive electrode and cause a short circuit. In that case, the curve at the time of charging may be disturbed or stretched, but since these were not observed in this battery and charging / discharging could be performed, it is possible to use a lithium foil as a negative electrode. Shown.

(Example 3) 1-nonanol sulfide / Li ₆ PS ₅ Br / Li Negative electrode all-solid-state lithium secondary battery
Li ₆ PS ₅ Br is LiBr (Kishida Chemical, 95%) 0.555g, Lithium Sulfide (Li ₂ S, Mitsuwa Chemical 99.9%) 0.734g, Diphosphorus Sulfide (P ₂ S ₅ , Sigma Aldrich, 99%) 0.710 g was placed in a zirconia pot with a zirconia disk, and mixed for 30 minutes with an experimental vibrating cup mill (MC-4A) manufactured by Ito Seisakusho. The mixed powder was press-molded with a force of 1 ton using a 15 mmΦ carbon die to prepare pellets. The pellets were placed in a gold crucible, heated to 550 ° C. in a quartz test tube under vacuum, and calcined for 2 hours. The obtained product was pulverized in a mortar and used as a solid electrolyte Li ₆ PS ₅ Br. This Li ₆ PS ₅ Br was measured by XRD (RINT TTR-III; Rigaku), and it was confirmed that it was 92% by weight Li ₆ PS ₅ Br with 8% by weight of lithium sulfide remaining. Conductivity measurements were performed on pellets (29 MPa) in which approximately 100 mg of solid electrolyte powder was compressed with a 10.1 mmΦ die, and it was confirmed that the material had a conductivity of 2.1 × 10 ^-3 S / cm.
A positive electrode mixture was prepared by mixing 1-nonanol sulfide (39 mg), a solid electrolyte (57 mg), and acetylene black (6 mg). Li ₆ PS ₅ Br91.6mg was put into a 10.1mmΦ pet tube and compressed with a stainless die with a force of 1t to create a solid electrolyte disk in the PET tube. 11.2 mg of positive electrode mixture was put on one side of the solid electrolyte disk and pressed with a force of 2.5 tons. A lithium foil (0.2 mmt, 8 mmΦ made by Honjo Metal) was attached to the other surface of the solid electrolyte disk and compressed by applying a force of 1 ton to prepare a 1-nonanol sulfide / solid electrolyte / Li battery. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 6, in the initial discharge, sulfur of 1-nonanol sulfide was reduced, lithium ions were occluded, and the capacity was 880 mAh / g. The discharge capacity of the second cycle was 516 mAh / g. Even with this battery, no phenomenon indicating a short circuit during charging was observed.

(Comparative Example 2) 1-nonanol sulfide / Li ₆ PS ₅ I / lithium negative electrode All-solid-state lithium secondary battery
LiI (Kishida Kagaku, 97%) 0.744g, Lithium Sulfur Sulfur (Li ₂ S, Mitsuwa Kagaku 99.9%) 0.638g, Diphosphorus Sulfide (P ₂ S ₅ , Sigma-Aldrich, 99%) 0.618g in a zirconia pot A zirconia disk was inserted, and the mixture was mixed with an experimental vibrating cup mill (MC-4A) manufactured by Ito Seisakusho for 30 minutes. The mixed powder was press-molded with a force of 1 ton using a 15 mmΦ carbon die to prepare pellets. The pellets were placed in a gold crucible, heated to 550 ° C. in a quartz test tube under vacuum, and calcined for 2 hours. The obtained product was pulverized four times for 30 minutes with a vibrating cup mill (MC-4A), and the obtained powder was used as a solid electrolyte Li ₆ PS ₅ I. This Li ₆ PS ₅ I was confirmed to be Li ₆ PS ₅ I with a small amount of lithium sulfide remaining by XRD (RINT TTR-III; manufactured by Rigaku) measurement. Conductivity measurements were performed on pellets (29 MPa) in which approximately 100 mg of solid electrolyte powder was compressed with a 10.1 mmΦ die, and it was confirmed that the material had a conductivity of 0.5 × 10 ^-3 S / cm.

A positive electrode mixture was prepared by mixing 38 mg of 1-nonanol sulfide, 64 mg of Li ₆ PS ₅ I, and 5 mg of acetylene black.
Li ₆ PS ₅ I107mg was put into a 10.1mmΦ pet tube and compressed with a stainless die with a force of 1t to create a solid electrolyte disk in the PET tube. 10 mg of the positive electrode mixture was put on one side of the solid electrolyte disk and pressed with a force of 2.5 tons. A lithium foil (0.2 mmt, 10 mmΦ made by Honjo Metal) was attached to the other surface of the solid electrolyte disk and compressed by applying a force of 1 ton to prepare a 1-nonanol sulfide / Li ₆ PS ₅ I / lithium battery. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 7, in the initial discharge, sulfur of 1-nonanol sulfide was reduced, lithium ions were occluded, and the capacity was 1041 mAh / g. The charging curve, which indicates a slight short circuit during charging in the second cycle, was torn and vibrated, and the charging capacity was seen to become extremely large after the third cycle. Although the discharge capacity in the second cycle is as high as 715 mAh / g, it was found that the lithium foil cannot be used as the negative electrode for the Li ₆ PS ₅ I solid electrolyte unless some measures are taken because the efficiency decreases due to a short circuit.

(Example 4) Polyimide coating 1-nonanol sulfide positive electrode / Li ₆ PS ₅ Cl / Li foil negative electrode All-solid-state lithium secondary battery
As the organic sulfur-based positive electrode material, an electrode having good characteristics can be obtained by using a polyimide as a binder, in which the electrode is not destroyed by expansion due to lithium occlusion in a battery using a conventional organic electrolytic solution (Non-Patent Document 1). ). If electrodes manufactured by such a well-known method can be brought into an all-solid-state battery, it will be a great advantage in the industrial production of the battery. A polyimide electrode of 1-nonanol sulfide was prepared and applied to an all-solid-state battery.

Kapton H was used as the polyimide. Two monomers constituting Kapton H were mixed as a solution to prepare a precursor. 2.0024 g (10 mmol) of 4,4'-Diaminodiphenyl Ether (Wako) was dissolved in 18.0761 g of N-methyl-2-pyrrolidone (Kishida Chemistry, 99.5%). On the other hand, 2.1849 g (10 mmol) of 1,2,4,5-Benzenetetracarboxylic Dianhydride (Wako) was dissolved in 18.013 g of N-methyl-2-pyrrolidone. When one of the transparent liquids was added to the other liquid, the color turned brown, and by stirring, it became a lemon yellow solution and slightly generated heat. At this time, the amino group and the carboxyl group were bonded to form a polyamic acid solution which is a precursor of polyimide. The solid content of this liquid is 10 weight percent.

0.2003 g of 1-nonanol sulfide was ground in a mortar and mixed with 0.0126 g of acetylene black in a dry manner, and then about 1 ml of N-methyl-2-pyrrolidone and 0.345 ml (0.375 g) of the above polyamic acid solution were added and mixed. It became a viscous slurry. The slurry was coated on aluminum foil with the coating thickness set to 150 microns with a doctor blade. After drying at 70 ° C. overnight, it was calcined at 300 ° C. for 1 hour under a nitrogen stream. The produced electrode is hereinafter referred to as a 1-nonanol polyimide sulfide electrode.

When this 1-nonanol sulfide polyimide electrode is punched out to a diameter of 10 mm in a glove box and the mass of the aluminum foil of the base material is subtracted, 1.1 mg of active material is applied, of which 0.88 mg is 1-nonanol sulfide. rice field. A PET tube was placed on a die, a 1-nonanol sulfide polyimide electrode was placed in the PET tube, and a solid electrolyte Li ₆ PS ₅ Cl 81.6 mg was placed on the electrode surface and pressed with 2 tons. A lithium foil (0.2 mmt, 8 mmΦ) was placed on the other surface of the solid electrolyte and pressed with a force of 1 ton to prepare a battery. A schematic cross-sectional view of the battery of Example 4 is as shown in FIG. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 9, the initial discharge showed a capacity of 915 mAh / g. The discharge capacity in the second cycle was 442 mAh / g, which was lower than that of the mixed-material electrode of Example 2, but showed a relatively large capacity as a positive electrode of a lithium ion secondary battery, and was an electrode outside the conventional glove box. It was found that the 1-nonanol sulfide polyimide electrode obtained by the production method was operable.

The electrodes of the all-solid-state battery are manufactured by coating a slurry in which a solid electrolyte, an active substance, and acetylene black are mixed with a rubber-based binder or the like in an argon atmosphere. The 1-nonanol sulfide polyimide electrode is excellent in that it is manufactured by a simple conventional method. Since 1-nonanol sulfide is wrapped in polyimide and acetylene black and does not contain a solid electrolyte that contributes to ion conduction even if it is in contact with it, part of the ion conduction is that of oxygen and nitrogen contained in the polyimide chain. It is thought that it is transmitted through non-shared electronic equality.

(Example 5) 1-nonanol sulfide + acetylene black polyimide coated positive electrode / Li ₆ PS ₅ Cl / lithium coated copper foil negative electrode All-solid-state lithium secondary battery
Due to the high pressure compression that is indispensable for manufacturing all-solid-state batteries, soft lithium foil may pass through small gaps such as cracks in the solid electrolyte and cause a short circuit, making it difficult to use lithium foil itself industrially. Is. Therefore, it was considered to apply lithium thinly to the copper foil and use it.

4 mg of metallic lithium foil was placed on the copper foil, heated with a soldering iron to melt it, and spread thinly on the copper foil. The basis weight of lithium on the copper foil was 1.65 mg / cm ² , which was 6.4 mAh / cm ² in terms of the capacity of the negative electrode.

This lithium-coated copper foil was put into a PET tube with a diameter of 10.1 mm, 77.8 mg of solid electrolyte Li ₆ PS ₅ Cl was put into it, and 1 ton of force was applied to compress it with a stainless die. A battery was prepared by adding the above-mentioned 1-nonanol sulfide + acetylene black polyimide coated positive electrode (10 mmφ, 5.2 mg, base material Al foil 4.1 mg, active material 0.9 mg) from above and pressing with a force of 2.5 tons. The schematic cross-sectional view of the battery of Example 5 is as shown in FIG. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 11, the initial discharge showed a capacity of 746 mAh / g. The discharge capacity of the second cycle was 312 mAh / g. It was shown that it is a battery system in which a copper foil coated with lithium can be used as a negative electrode.

(Example 6) 1-nonanol sulfide + acetylene black polyimide coated positive electrode / Li ₆ PS ₅ Cl / lithium coated titanium foil negative electrode All-solid-state lithium secondary battery
4 mg of metallic lithium foil was placed on a titanium foil (99.5% made by Niraco, 0.02 mmt), heated with a soldering iron to melt it, and spread thinly to form a lithium layer. The basis weight of lithium on the titanium foil was 1.8 mg / cm ² , which was 7.0 mAh / cm ² in terms of the capacity of the negative electrode.

This lithium-coated titanium foil was placed in a 10.1 mmΦ pet tube, and then 78.9 mg of the solid electrolyte Li ₆ PS ₅ Cl was placed and compressed with a stainless die using a force of 1 ton. A battery was prepared by adding the above-mentioned 1-nonanol sulfide + acetylene black polyimide coated positive electrode (10 mmφ, 5.1 mg, base material Al foil 4.1 mg, active material 0.8 mg) from above and pressing with a force of 2.5 tons. A schematic cross-sectional view of the battery of Example 6 is as shown in FIG. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 13, the initial discharge showed a capacity of 573 mAh / g. The discharge capacity of the second cycle was 583 mAh / g. The discharge capacity and the capacity at 10 cycles were higher than those when the copper foil base material was used. It was shown that it is a battery system in which a titanium foil coated with lithium can be used as a negative electrode.

(Example 7) 1-nonanol sulfide + acetylene black polyimide coated positive electrode / Li ₆ PS ₅ Cl / lithium coated stainless steel foil negative electrode All-solid-state lithium secondary battery
4 mg of metallic lithium foil was placed on a stainless steel foil (SUS316, 0.01 mmt manufactured by Niraco), heated with a soldering iron to melt it, and spread thinly to form a lithium layer. The basis weight of lithium on the stainless steel foil was 1.0 mg / cm ² , which was 3.9 mAh / cm ² in terms of the capacity of the negative electrode.

This lithium-coated stainless steel foil was placed in a 10.1 mmΦ pet tube, and then 75.0 mg of the solid electrolyte Li ₆ PS ₅ Cl was placed and compressed with a stainless die using a force of 1 ton. A battery was prepared by adding the above-mentioned 1-nonanol sulfide + acetylene black polyimide coated positive electrode (10 mmφ, 5.4 mg, base material Al foil 4.1 mg, active material 1.0 mg) from above and pressing with a force of 2.5 tons. A schematic cross-sectional view of the battery of Example 7 is as shown in FIG. This battery was charged and discharged by starting from discharging in the range of 3-1V and fixing it at a current of 0.05mA. As shown in FIG. 15, the initial discharge showed a capacity of 908 mAh / g. The discharge capacity of the second cycle was 433 mAh / g. The discharge capacity and the capacity at 10 cycles were higher than those when the copper foil base material was used. It was shown that it is a battery system in which a stainless steel foil coated with lithium can be used as a negative electrode.

(Example 8) 1-nonanol sulfide + acetylene black polyimide coated positive electrode / Li ₆ PS ₅ Cl / lithium coated silicon polyimide coated all-solid-state lithium secondary battery consisting of negative electrode
As a method of supporting lithium on silicon in a short time, we examined a lithium-coated silicon polyimide negative electrode based on the idea that the battery system would be completed by carrying lithium, which the sulfur-based positive electrode does not have, on the negative electrode. ..

The method for manufacturing the silicon polyimide negative electrode is as follows. Nanosilicon (particle size: 30-50 nm, Nanostructured & Amorphous Materials) is mixed with acetylene black and polyamic acid (Skybond, manufactured by IST), which is a precursor of polyimide, at a weight ratio of 80: 5: 15, N-methyl-2. -Mix pyrrolidone (NMP) as a solvent to prepare a slurry, apply this slurry on a copper foil, dry it at 80 ° C, treat it in vacuum at 300 ° C for 10 hours to make it polyimide, and perform siliconization. A silicon polyimide electrode sheet having an amount of 1.5 mg / cm ² was prepared. 4 mg of metallic lithium foil was placed on this silicon polyimide electrode, heated with a soldering iron to melt it, and spread thinly on the electrode.

Put this lithium-coated silicon polyimide negative electrode 7.6 mg (10 mmφ, lithium 1.1 mg, silicon polyimide 1.0 mg, base copper foil 5.5 mg) in a 10.1 mmΦ pet tube, and then put 74.0 mg of solid electrolyte Li ₆ PS ₅ Cl. It was compressed with a stainless die with a force of 1 ton. The above-mentioned 1-nonanol sulfide + acetylene black polyimide coated positive electrode 5.3 mg (10 mmφ, base material Al foil 4.0 mg, active material 1.0 mg) was put on it and pressed with a force of 2.5 tons to prepare a battery. The schematic cross-sectional view of the battery of Example 8 is as shown in FIG. This battery was charged and discharged in the range of 2.7-0.7V, starting from discharging and fixing at a current of 0.05mA. As shown in FIG. 17, the initial discharge showed a capacity of 1081 mAh / g. The discharge capacity of the second cycle was 517 mAh / g. This indicates that both the positive electrode and the negative electrode manufactured by the conventional method using polyimide as a binder can be used as a full cell in an all-solid-state battery using a sulfide solid electrolyte.

(Example 9) 1-nonanol sulfide + acetylene black polyimide coated positive electrode / Li ₆ PS ₅ Cl + rubber binder coated electrolyte / lithium coated silicon polyimide coated all-solid-state lithium secondary battery consisting of negative electrode
The all-solid-state lithium secondary battery composed of the polyimide coated positive electrode of 1-nonanol sulfide + acetylene black of Example 8 positive electrode / dust Li ₆ PS ₅ Cl / lithium coated silicon polyimide coated negative electrode is the compact Li ₆ PS which is an electrolyte. ₅ Cl is 74 mg, which accounts for 85% of the total mass of the battery. Reducing this electrolyte contributes to the energy density of the battery. Therefore, an electrolyte slurry was prepared with a rubber-based binder, and the weight and layer thickness of the battery were examined by applying it to the positive electrode.

A negative electrode using polyimide as a binder and a lithium-coated silicon polyimide negative electrode 8.9 mg (10 mmφ, lithium 2.4 mg, silicon polyimide 1.0 mg, base copper foil 5.5 mg) similar to those used in Example 8 were used. In addition, a heptane solution (3 drops) containing 0.7 ml of heptane (Kishida Chemical, 99%) and 1.4 mg of rubber-based binder (MP-10) was added to 107.1 mg of solid electrolyte (Li ₆ PS ₅ Cl) to prepare a slurry. It was applied to a polyimide coated positive electrode of 1-nonanol sulfide + acetylene black (mass of 10 mmφ, mass 5.7 mg, base material Al foil 4.1 mg, active material 1.3 mg, solid electrolyte + rubber binder mass 14.9 mg). The mass of 10 mmφ of this coated electrode was 20.6 mg.

This lithium-coated silicon polyimide negative electrode was placed on top of each other and placed in a 10.1 mmΦ pet tube, and compressed with a stainless die using a force of 2 tons to prepare a battery. A schematic cross-sectional view of the battery of Example 9 is as shown in FIG. This battery was charged and discharged in the range of 3.0-0.6V, starting from discharging and fixing at a current of 0.05mA. As shown in FIG. 19, the initial discharge showed a capacity of 582 mAh / g. The discharge capacity of the second cycle was 173 mAh / g. Although the capacity is lower than that of the compacted solid electrolyte, by using the rubber binder of the coated solid electrolyte, the total weight of the battery is 29.5 mg, which is one-third of the 86.9 mg of the compacted battery, and the thickness is 0.70. I was able to make it as thin as 0.24 mm from mm. We were able to manufacture a battery that operates at the volume required for practical use.

Claims (2)

Molten lithium is applied to an organic sulfur-based positive electrode containing a polyimide resin binder, a sulfide-based solid electrolyte containing chlorine and / or bromine, and a silicon particle-containing polyimide resin binder layer provided on one side of a substrate. An all-solid-state battery having a negative electrode obtained from the above. The all-solid-state battery according to claim 1 , wherein the sulfide-based solid electrolyte contains a rubber-based binder.

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