KR20150143365A - All solid battery and preparation method thereof - Google Patents

Abstract

The present invention relates to a battery which comprises: a porous positive electrode; a negative electrode facing the positive electrode; a first solid electrolyte provided on at least one portion of an inner pore or a surface of the positive electrode; and a second solid electrolyte provided on at least one side, which faces the positive electrode, of the negative electrode, wherein at least one electrolyte of the first and the second solid electrolyte is solid. The present invention further relates to a production method thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solid-

This application claims the benefit of the filing date of Korean Patent Application No. 10-2014-0072474 filed with the Korean Intellectual Property Office on June 13, 2014, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD [0001] The present invention relates to a whole solid battery and a manufacturing method thereof.

With the miniaturization and weight reduction of portable electronic devices, there is a continuing need for high capacity, miniaturization and stabilization of the lithium secondary battery used as its power source. Therefore, it is essential to develop a high-performance, ultra-small and light-weight battery. In particular, a battery that satisfies these conditions while charging and discharging is possible in consideration of economical aspects is a battery including a solid electrolyte.

In the battery including the solid electrolyte, the solid electrolyte may be deposited on the electrode within a few micrometers using a thin film deposition technique.

However, the thin film battery in which the electrode and the solid electrolyte are laminated using the above-mentioned thin film deposition technique is disadvantageous in terms of capacity and size.

Accordingly, attempts have been made to increase the area of the cathode or to increase the thickness thereof in order to increase the capacity of the battery including the solid electrolyte. This is because the energy density, reversibility and discharge speed, which are important factors in the performance of a battery including a general solid electrolyte, are determined by the cathode material among the constituent elements of the battery. Therefore, it is important to develop a suitable cathode material in order to use it at a high energy density for a long time, and in particular, it is necessary to increase the thickness of the anode.

As described above, in order to increase the capacity of a battery, a technology for increasing the capacity of a battery by forming a thick anode by a thick film process in which an electrode active material rather than a thin film is mixed with a solid electrolyte is used as a composite material, However, when the thickness of the anode is increased by the thick film, the contact between the particles is poor and voids are generated. As a result, the internal resistance of the battery becomes very high, A phenomenon appears.

Therefore, development of a battery having improved charging / discharging efficiency, capacity, specification, and stability compared to a battery using a conventional liquid electrolyte by applying a solid electrolyte is required.

Korean Patent Application Publication No. 2004-0047610

The present specification is intended to provide a pre-solid battery and a method of manufacturing the same.

According to one embodiment of the present disclosure,

A positive electrode of porous structure;

A negative electrode facing the positive electrode;

A first solid electrolyte provided on at least a part of inner pores and surfaces of the anode; And

And a second solid electrolyte provided on a surface of the negative electrode opposite to at least the positive electrode.

According to another embodiment of the present invention, the first solid electrolyte comprises a polymer electrolyte.

According to another embodiment of the present invention, the second solid electrolyte comprises at least one of a polymer electrolyte, an inorganic electrolyte, and a lithium-ion exchange material.

In addition, one embodiment of the present invention provides a method of manufacturing the pre-solid battery.

According to one embodiment of the present invention, it is possible to manufacture a pre-solid battery with improved safety and / or efficiency. In addition, according to the embodiments of the present invention, it is possible to manufacture a full-thickness solid-state battery in a thick-film form, thereby enabling the capacity of the entire solid-state battery to be increased.

1 is a schematic view of a battery including a solid electrolyte.
FIG. 2 is a graph showing initial charging / discharging results of all solid-state batteries according to an embodiment of the present invention. FIG.

Hereinafter, the present invention will be described in more detail.

The pre-solid battery according to one embodiment of the present invention

A positive electrode of porous structure;

A negative electrode facing the positive electrode;

A first solid electrolyte provided on at least a part of inner pores and surfaces of the anode; And

And a second solid electrolyte provided on a surface of the negative electrode facing at least the positive electrode.

In a lithium ion battery, during the discharging process, lithium ions move from the cathode to the anode through the electrolyte, and when charged, lithium ions move back from the anode to the cathode through the electrolyte and find their positions. When the liquid phase electrolyte used in the conventional lithium ion battery is replaced with a solid phase, ignition and explosion due to the decomposition reaction of the electrolyte and the like are not generated at all, so that safety can be greatly improved. On the other hand, in order to solve the problem that the contact property between the electrode active material and the electrolyte is poor when the solid electrolyte is used, the first solid electrolyte is applied to the anode of the porous structure as described above in the embodiments of the present invention do. The first solid electrolyte is applied to the positive electrode of the porous structure to widen the surface area of the positive electrode active material and the type of the first solid electrolyte provided on the anode side is appropriately selected to improve the contact property between the positive electrode active material and the first solid electrolyte have. For example, a polymer electrolyte material may be used as the first solid electrolyte material. More preferably, the above-mentioned contact property can be greatly improved by allowing the first solid electrolyte to include a polymer electrolyte having impregnation or wetting property with respect to the inside of the anode of the porous structure. Such a configuration can achieve higher safety and efficiency, unlike the technique of mixing the cathode active material and the solid electrolyte.

In addition, according to the embodiments of the present disclosure, a two-layered solid electrolyte is included by using a first solid electrolyte on the anode of the porous structure and a second solid electrolyte on the cathode side. This makes it possible to freely select the materials and the thicknesses of the respective solid electrolytes, thereby maximizing the safety and efficiency of the battery.

According to one embodiment of the present disclosure, the first solid electrolyte is provided on at least a part of the inner pores of the anode of the porous structure and at least a part of the outer surface.

According to one embodiment of the present invention, the first solid electrolyte is provided on at least a part of the inner pores of the anode of the porous structure and the entire outer surface.

1 is a schematic view of a battery according to an embodiment of the present invention. 1, the first solid electrolyte 12 is present on the entire outer surface of the anode 11 of the porous structure and at least a part of the inner pores to form the composite 12 including the anode and the first solid electrolyte . Also, a laminate 20 in which the cathode 21 and the second solid electrolyte 22 are laminated is applied. As shown in FIG. 1, the first solid electrolyte is provided on at least a part of the outer surface of the anode and the inner pores of the porous structure, thereby greatly improving the contact characteristics between the cathode active material and the electrolyte. Furthermore, when the polymer electrolyte having impregnation property or wettability with respect to the inside of the anode is used as the first solid electrolyte, the above contact property can be further improved.

Although the lithium ion battery has been described above, the scope of the present invention is not limited thereto. The present invention is also applicable to other types of batteries such as a sodium battery, a magnesium battery, and a calcium battery, and lithium batteries or sodium batteries are preferable. The entire solid battery described in this specification may be a primary battery or a secondary battery, but it is preferably a secondary battery.

According to another embodiment of the present invention, the first solid electrolyte comprises a polymer electrolyte.

As the material of the first solid electrolyte, a polymer electrolyte may be used, and the polymer electrolyte is not particularly limited as long as it has an ion conductive property and an insulating property for performing an electrolyte function. Polymer electrolytes are easy to process, have high flexibility, and are safe. The first solid electrolyte preferably includes a polymer electrolyte having impregnation or wettability with respect to the interior of the anode of the porous structure.

According to another embodiment of the present invention, the polymer electrolyte is not particularly limited as long as it is an ion conductive polymer. For example, the polymer electrolyte may include at least one selected from the group consisting of a hydrocarbon-based polymer, a fluorine-based polymer, and a polyether-based polymer.

The hydrocarbon-based polymer may be selected from the group consisting of a sulfonated polyimide, a sulfonated polysulfone, a polyphenylene ether-based polymer, a sulfonated polybenzoxazole, a ketal group-containing polymer, a sulfonate ester-containing polymer and a polybenzonitrile copolymer But is not limited thereto.

The fluoropolymer includes, but is not limited to, polytetrafluoroethylene (PTFE), Nafion, and the like.

The polyether-based polymer includes, but is not limited to, polyethylene oxide (PEO).

According to an embodiment of the present invention, the first solid electrolyte may further include an electrolyte salt, and the electrolyte salt may be a lithium salt, preferably lithium bis (trifluoromethylsulfonyl) imide , But is not limited thereto.

According to another embodiment of the present disclosure, the anode of the porous structure may be composed of a cathode material known in the art, except that it has a porous structure. The anode includes a cathode active material, and if necessary, a binder or other additives may be added.

Examples of the positive electrode active material is LiNi _x Co _{0 0 .8-. 2} Al _x O ₂ , LiCo _x Mn _y O ₂ , LiNi _x Co _y O ₂ , LiNi _x Mn _y O ₂ , LiNi _x Co _y Mn _z O ₂ , LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiFePO ₄ , LiCoPO ₄ , Lithium transition metal oxides such as LiMnPO ₄ and Li ₄ Ti ₅ O ₁₂ ; Cu ₂ Mo ₆ S ₈ , chalcogenides such as FeS, CoS and MiS, but are not limited thereto.

The shape of the cathode active material is not particularly limited and may be a particle shape, for example, a spherical shape, an elliptical shape, a rectangular parallelepiped shape, or the like. The average particle diameter of the cathode active material may be within the range of 1 to 50 占 퐉, but is not limited thereto. The average particle diameter of the cathode active material can be obtained, for example, by measuring the particle size of the active material observed by a scanning electron microscope and calculating the average value thereof.

The binder contained in the positive electrode is not particularly limited, and a fluorine-containing binder such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) may be used.

The content of the binder is not particularly limited as long as it can fix the cathode active material, and may be in the range of 0 to 10 wt% with respect to the whole anode.

If a first solid electrolyte is applied to the anode, a binder may not be required. This is because the first solid electrolyte can also function as a binder.

The anode may further include a conductive material. The conductive material is not particularly limited as long as it can improve the conductivity of the anode, and may include acetylene black, carbon fiber, and the like. The content of the conductive material may be selected in consideration of other battery conditions such as the kind of the conductive material, and may be, for example, within the range of 1 to 10 wt% with respect to the entire anode.

According to one embodiment of the present invention, the porosity of the anode of the porous structure may be within a range of 0.01 to 50%, but is not limited thereto.

According to another embodiment of the present disclosure, the cathode has a non-porous structure.

According to another embodiment of the present disclosure, the non-porous cathode is advantageous for manufacturing a high capacity battery. For example, when a metallic foil is directly used as a non-porous cathode, a very high capacity battery can be provided.

According to another embodiment of the present disclosure, the cathode comprises a metal. The metal included in the negative electrode includes a single metal such as lithium or sodium, or two or more metal alloys. For example, in the case of a lithium battery, the negative electrode includes lithium or a lithium alloy. The cathode may have the form of a metal foil.

According to another embodiment of the present invention, when the anode contains lithium, since lithium is light, it has the highest theoretical capacity, and the oxidation and reduction potentials are lowest in the metal, so that a high capacity battery can be realized.

According to one embodiment of the present invention, the second solid electrolyte is not limited as long as it is an electrolyte material having ion conductivity. Since the negative electrode has a non-porous structure, the material of the second solid electrolyte provided on the negative electrode side is not particularly limited. For example, the second solid electrolyte may include at least one of a polymer electrolyte, an inorganic electrolyte, and a lithium-ion exchange material.

When the second solid electrolyte comprises a polymer electrolyte, it may be the same kind as the polymer electrolyte included in the first solid electrolyte described above, or may be a different kind. The description of the polymer electrolyte exemplified as the first solid electrolyte material described above can be applied to the polymer electrolyte that can be used as the material of the second solid electrolyte.

The inorganic electrolyte may include at least one selected from the group consisting of sulfides, oxides, nitrides, halides, and phosphates.

As the sulfide, an electrolyte material known in the art may be used. For example, P ₂ S ₅ -Li ₂ S-based, B ₂ S ₃ -Li ₂ S-based, Li _{4 - x} Ge _{1 - x} P _x S ₄ (0 _{? X? 1} ), Li _{4 - x} Ge _{1 - x} P _x S ₁ (0? X? 1), but the present invention is not limited thereto.

As the oxide, an electrolyte material known in the art can be used. Examples of the oxide include GeO ₂ , Li ₄ SiO ₄ , (La, Li) TiO ₃ and LiAl _x Co _{1 - x} O ₂ ), But are not limited thereto.

Examples of the phosphate include Li _{1 + x} Al _x Ge _{2 -x} (PO ₄ ) ₃ (0? _X ? 0.5), Li _{1 + x} Ti _{2 - x} Al (PO ₄ ) ₃ (0? _X ? 0.4) and Li _{1 + x} Ti _2-x Al _x (PO ₄ ) ₃ (0? _X ? 0.4).

As the nitride, an electrolyte material known in the art may be used. For example, lithium nitride, lithium alloy nitride, or the like may be used, but the present invention is not limited thereto.

As the halide, an electrolyte material known in the art may be used. For example, lithium halide, lithium alloy halide, or the like may be used, but the present invention is not limited thereto.

According to another embodiment of the present disclosure, the lithium-ion exchange material includes at least one selected from the group consisting of a hydrocarbon-based ion exchange material, a fluorine-based ion exchange material, and a polyether-based ion exchange material.

According to another embodiment of the present invention, the hydrocarbon-based ion exchange material is a sulfonated polyimide, a sulfonated polysulfone, and a polyphenylene ether-based polymer; Sulfonated polybenzoxazole; Polymer containing ketal group; A sulfonic acid ester-containing polymer; And polybenzonitrile copolymers, but the present invention is not limited thereto.

According to another embodiment of the present invention, the fluorine-based ion exchange material includes at least one selected from the group consisting of polytetrafluoroethylene (PTFE) and nafion, but is not limited thereto.

According to another embodiment of the present disclosure, the polyether ion exchange material includes, but is not limited to, polyethylene oxide (PEO).

According to another embodiment of the present invention, the thickness of the second solid electrolyte may be selected as required, for example, 1 nm to 100 占 퐉. The second solid electrolyte may serve not only as an electrolyte on the cathode side, but also as a separator separating the anode and the cathode. When the second solid electrolyte provided on the cathode side is too thick, the weight of the second solid electrolyte increases, thereby reducing the energy density per unit weight of the whole battery. In view of this, one skilled in the art can select an appropriate second solid electrolyte thickness.

According to one embodiment of the present disclosure, a method of manufacturing a pre-solid battery is provided. For example, the method of manufacturing the pre-solid battery includes forming a first solid electrolyte on the anode having a porous structure; Forming a second solid electrolyte on the cathode, and assembling a cathode having the first solid electrolyte and a cathode having the second solid electrolyte.

In this specification, the formation of the first solid electrolyte and the second solid electrolyte can be carried out using a method known in the art. For example, there can be used a sintering method, a chemical vapor deposition method, a metal substitution method, a spraying method, a filtering method, a dip coating method, a bar coating method, Inkjet printing, and inkjet printing. However, the present invention is not limited thereto.

Hereinafter, preferred embodiments and examples of the present invention will be described in order to facilitate understanding of the present invention. However, the following Preparation Examples and Examples are provided for illustrating the present invention, and thus the scope of the present invention is not limited thereto.

<Production Example>

PREPARATION EXAMPLE 1. Preparation of First Solid Electrolyte and Positive Electrode Including It

Lithium salt of polyethylene oxide (PEO) and lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) was added to the solvent at a ratio of ethylene oxide (EO) / Li = 9, An electrolyte solution was prepared. In the polymer electrolyte solution, the conductive material and LiNi _{0 .8 - x} Co _{0 . 2} Al _x O ₂ (NCA) active material was mixed in a weight ratio of active material: polyelectrolyte: conductive material = 75.52: 20.29: 4.19 and mixed with a paste mixer to prepare a slurry. The slurry was applied on an aluminum foil and then a cathode was prepared using a bar coater.

Production Example 2. Preparation of Second Solid Electrolyte and Negative Electrode Containing It

The starting materials Li ₂ S and P ₂ S _5, 45ml ball mill of the LiCl ZrO ₂ material (ball mill) and then put into a container and added to seal the vessel to 5mm ZrO ₂ ball (ball) planetary ball mill (planetary ball mill. And then subjected to mechanical milling at 500 rpm for 40 hours to prepare Li ₂ SP ₂ S ₅ -LiCl as the second solid electrolyte.

Li ₂ SP ₂ S ₅ -LiCl was mixed with a polyvinylidene fluoride (PVDF) solution (PVDF: toulene = 8: 92 wt%) to prepare a slurry and then applied to a thickness of 50 μm on 150 μm lithium foil To prepare a second solid electrolyte and a negative electrode containing the same.

<Examples>

Example 1 Preparation of a Whole Solid Battery

The positive electrode and negative electrode (negative electrode whose surface was covered with the solid electrolyte) prepared in Preparation Examples 1 and 2 were pulverized to a size of? 14 and? 15, respectively, and pressed at 400 MPa, assembled in a 2032 coin cell All solid batteries were prepared.

&Lt; Evaluation example &

Evaluation example 1. Evaluation of cell

The cells of Example 1 were charged and discharged at 60 DEG C in the range of 2.5 V to 4.2 V at 0.1 C, and the results are shown in FIG.

2 is a diagram showing the initial charge / discharge results of all solid-state cells according to an embodiment of the present invention.

Through the graph of FIG. 2, it can be seen that the pre-solid battery according to the present invention works effectively.

10: Composite of anode and first solid electrolyte
11: anode of porous structure
12: First solid electrolyte
20: A laminate of a negative electrode and a second solid electrolyte
21: cathode
22: Second solid electrolyte

Claims (9)

A positive electrode of porous structure;
A negative electrode facing the positive electrode;
A first solid electrolyte provided on at least a part of inner pores and surfaces of the anode; And
And a second solid electrolyte provided on a surface of the negative electrode opposite to at least the positive electrode. The pre-solid battery according to claim 1, wherein the first solid electrolyte comprises a polymer electrolyte. The pre-solid battery according to claim 2, wherein the polymer electrolyte comprises at least one selected from the group consisting of a hydrocarbon-based polymer, a fluorine-based polymer, and a polyether-based polymer. The pre-solid battery according to claim 1, wherein the cathode comprises a metal. The pre-solid battery according to claim 1, wherein the second solid electrolyte comprises at least one of a polymer electrolyte, an inorganic electrolyte and a lithium-ion exchange material. The pre-solid battery according to claim 5, wherein the polymer electrolyte comprises at least one selected from the group consisting of a hydrocarbon-based polymer, a fluorine-based polymer, and a polyether-based polymer. The pre-solid battery according to claim 5, wherein the inorganic electrolyte comprises at least one selected from the group consisting of sulfides, oxides, nitrides, halides and phosphates. The pre-solid battery according to claim 5, wherein the lithium-ion exchange material comprises at least one selected from the group consisting of a hydrocarbon-based ion exchange material, a fluorine-based ion exchange material, and a polyether-based ion exchange material. Forming a first solid electrolyte on the anode of the porous structure;
Forming a second solid electrolyte on the cathode; And
The method of any one of claims 1 to 8, comprising the step of assembling a cathode having the first solid electrolyte and a cathode having the second solid electrolyte.

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