KR102223866B1 - Preparation method of composite cathode for solid-state lithium-ion secondary battery - Google Patents

Abstract

The present invention relates to a method of manufacturing a composite positive electrode for a solid-state lithium ion battery.
A method for manufacturing a composite positive electrode for a solid-state lithium ion battery according to an embodiment of the present invention includes: preparing a positive electrode active material powder; Coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; Performing any one or more of primary polymerization and crosslinking of a material containing the coated polymer electrolyte monomer to obtain a polymer-coated positive electrode active material powder; Positioning a positive electrode active material coated with a polymer on a current collector; Injecting a material containing a second polymer electrolyte monomer into the current collector; And secondary polymerization of a material including a monomer for a second polymer electrolyte.

Description

Method for manufacturing composite anode for solid-state lithium-ion battery {PREPARATION METHOD OF COMPOSITE CATHODE FOR SOLID-STATE LITHIUM-ION SECONDARY BATTERY}

The present invention relates to a method of manufacturing a composite positive electrode for a solid-state lithium ion battery. More specifically, it relates to a positive electrode active material for a solid-state lithium ion battery-polymer electrolyte composite positive electrode manufacturing method.

In recent years, portable cordless products such as portable audio devices, multimedia players, mobile phones, smartphones, notebook-type personal computers, tablet-type devices, and video cameras are required to be miniaturized, lightweight, thinner, and portable. In addition, from the viewpoint of environmental problems such as air pollution and an increase in carbon dioxide, hybrid vehicles and electric vehicles are being developed and put into practical use. Accordingly, these electronic devices and electric vehicles require excellent secondary batteries having features such as high efficiency, high output, high energy density, and light weight, and development and research of various secondary batteries as secondary batteries having such characteristics are required. It is being done. In a rechargeable secondary battery, a structure that prevents direct electrical contact between a positive electrode and a negative electrode by spaced apart between a positive electrode (a positive electrode, a cathode) and a negative electrode (a negative electrode, an anode) by a porous polymer film containing an organic electrolyte. It is made into. In the currently commercialized lithium ion battery, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , Li(Ni _x Co _y Mn _z )O _2, etc. are used as 4V-class positive electrode active materials. On the other hand, as a negative electrode, a graphite-based negative electrode material is mainly used, but many studies have been made on alkali metals including metallic lithium. In particular, lithium metal is considered an ideal negative electrode material because it has a high theoretical energy density (weight capacity density 3861 mAh/g) and a low charge/discharge potential (-3.045V vs. SHE).

As the electrolytic solution, for example, a lithium salt dissolved in a non-aqueous organic solvent is used, which has good ionic conductivity. However, a solid electrolyte was developed due to the stability problem of the electrolyte in solution. In the development of solid electrolytes, initially, low ionic conductivity was a problem, but these shortcomings were significantly overcome. In addition, a method of manufacturing a composite positive electrode or a composite negative electrode by adding a solid electrolyte to the positive electrode or negative electrode has been developed, rather than simply placing a solid electrolyte between the positive electrode and the negative electrode.

Regarding the method of manufacturing a composite positive electrode, it is one of the positive electrode active material-polymer electrolyte composite positive electrode manufacturing methods.After preparing a porous electrode such as a positive electrode active material-solid electrolyte, a liquid monomer is injected and then solidified through polymerization. There is a way to make it. However, since this has a shrinkage problem during polymerization, there is a need for a way to improve this.

The present invention is to provide a method of manufacturing a composite positive electrode for a solid-state lithium ion battery. More specifically, to provide a positive electrode active material for a solid-state lithium ion battery-polymer electrolyte composite positive electrode manufacturing method.

A method for manufacturing a composite positive electrode for a solid-state lithium-ion battery according to an embodiment of the present invention includes: preparing a positive electrode active material powder; Coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; Performing any one or more of primary polymerization and crosslinking of a material containing the coated polymer electrolyte monomer to obtain a polymer-coated positive electrode active material powder; Positioning a positive electrode active material coated with a polymer on a current collector; Injecting a material containing a second polymer electrolyte monomer into the current collector; And secondary polymerization of a material containing a second polymer electrolyte monomer.

The material containing the monomer may be the monomer itself.

The material containing the monomer may be liquid.

The monomer may include one selected from polyethylene glycol (PEO), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), polypropylene glycol dimethacrylate (PPGMA), and combinations thereof.

Coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; And injecting a material containing a second polymer electrolyte monomer into the current collector; may be coating or injecting a material containing a monomer and a lithium salt together.

Lithium salts are LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ CO ₂ , LiSbF ₆ , _{LiAlCl 4} , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, LiC( CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carboxylic acid, lithium 4-phenyl borate, imide, and a combination thereof Can include.

In the step of coating the surface of the positive electrode active material powder with a material including a monomer for a first polymer electrolyte, the amount of the material including the monomer relative to the precursor particles may be 0.1 to 20% by weight.

The composite positive electrode for a solid-state lithium ion battery according to an embodiment of the present invention significantly reduces the contact resistance between the positive electrode active material powder and the polymer, thereby improving the output characteristics of the solid polymer electrolyte battery and reducing dead ions. As a result, the capacity and cycle characteristics of the battery are improved.

1 schematically shows a conventional method for manufacturing a composite anode.
2 schematically shows a method of manufacturing a composite anode according to an embodiment of the present invention.

In this specification, terms such as first, second and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

In the present specification, parts irrelevant to the description are omitted in order to clearly describe the present invention, and the same reference numerals are attached to the same or similar components throughout the specification.

In the present specification, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

In this specification, the terminology used is only for referring to specific embodiments and is not intended to limit the present invention. Singular forms as used herein also include plural forms unless the phrases clearly indicate the opposite. As used in the specification, the meaning of "comprising" specifies a specific characteristic, region, integer, step, action, element and/or component, and the presence of another characteristic, region, integer, step, action, element and/or component, or It does not exclude additions.

In the present specification, the term "combination of these" included in the expression of the Makushi form refers to a mixture or combination of one or more selected from the group consisting of the constituent elements described in the expression of the Makushi form, and the constituent elements It means to include one or more selected from the group consisting of.

In this specification, when a part is referred to as being "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when a part is referred to as being "directly above" another part, no other part is interposed between them.

Although not defined differently, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms defined in a commonly used dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal meaning unless defined.

In addition, unless otherwise specified,% means% by weight, and 1 ppm is 0.0001% by weight.

First, the prior art is a technology for manufacturing a composite positive electrode by injecting a liquid monomer after preparing a porous electrode such as a positive electrode active material-polymer electrolyte, and solidifying through polymerization. However, there is a problem when manufacturing a composite anode using such a conventional technique. This is shown in FIG. 1. In the liquid monomer state, the contact between the positive electrode active material powder and the liquid monomer is good, but when polymerization proceeds, the contact between the positive electrode active material and the solid electrolyte is not smooth due to shrinkage of the polymer, which causes an increase in resistance. Since the direction of polymer shrinkage is the direction of the center of the positive electrode active material and the length between the polymers is reduced, there is a possibility that a crack between the positive electrode active material and the polymer may be caused.

Accordingly, the inventors of the present invention devised a method for manufacturing a composite anode as follows.

A method for manufacturing a composite positive electrode for a solid-state lithium-ion battery according to an embodiment of the present invention includes: preparing a positive electrode active material powder; Coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; Performing any one or more of primary polymerization and crosslinking of a material containing the coated polymer electrolyte monomer to obtain a polymer-coated positive electrode active material powder; Positioning a positive electrode active material coated with a polymer on a current collector; Injecting a material containing a second polymer electrolyte monomer into the current collector; And secondary polymerization of a material containing a second polymer electrolyte monomer.

2 is a first polymer electrolyte monomer coated on the surface of the positive electrode active material powder, and the coated polymer electrolyte monomer was first polymerized or cross-linked to obtain a polymer-coated positive electrode active material powder. A schematic illustration of a step of, after that, a second polymer electrolyte monomer is injected, and a second polymerization step of the injected polymer electrolyte monomer is shown.

As can be seen in FIG. 2, through the first coating and the first polymerization and/or crosslinking, the polymer shrinks in the direction of the center of the positive electrode active material powder, thereby minimizing the gap between the polymers coated with the positive electrode active material first, and mechanically Contact is better first. Thereafter, through secondary injection and secondary polymerization, the empty space in the electrode can be filled, and unlike the prior art, the contact between the positive electrode active material and the polymer is good, so that problems such as increase in resistance and occurrence of cracks do not occur. Also, the ionic conductivity inside the anode is improved.

Meanwhile, the material including the monomer for the first polymer electrolyte and the material including the monomer for the second polymer electrolyte may be of the same type or different types. More specifically, they may be of the same type. When they are of the same type, the anode efficiency may be better.

In this case, the material containing a monomer means a monomer itself or a material in which two or more monomers are bonded. More specifically, a material in which two or more monomers are bonded may be one in which 1000 or less monomers are bonded. A material in which 1000 or more monomers are bonded has a disadvantage in that it is difficult to infiltration due to reduced fluidity.

More specifically, the material containing the monomer may be the monomer itself. At this time, the monomer (monomer) refers to a material having a small molecular weight that becomes a unit constituting a polymer compound or a compound. The reason why the monomer is more advantageous is that when it is used for the first polymer electrolyte, the monomer is usually in a liquid state, so it is easy to evenly apply the surface of the positive electrode active material during the first coating. This is because it is possible to improve the contact between the positive electrode active material particles and the first polymer electrolyte. In addition, even when used for the second polymer electrolyte, infiltration can be facilitated when it is a liquid having a low viscosity. When used as a second polymer electrolyte, adding a plasticizer can reduce side effects caused by shrinkage caused by polymerization or crosslinking.

In addition, the material containing the monomer may be liquid.

Meanwhile, the monomer may include one selected from polyethylene glycol (PEO), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), polypropylene glycol dimethacrylate (PPGMA), and combinations thereof. .

In addition, coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; And injecting a material containing a second polymer electrolyte monomer into the current collector; may be coating or injecting a material containing a monomer and a lithium salt together.

At this time, the lithium salt is LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ CO ₂ , LiSbF ₆ , _{LiAlCl 4} , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, 1 selected from LiC(CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carboxylic acid, lithium 4-phenyl borate, imide, and combinations thereof It may contain species.

In addition, coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; In, the amount of the material containing the monomer relative to the precursor particles may be 0.01 to 20% by weight. If the amount of the material containing the monomer is too large, the distance between the positive electrode active material particles increases, thereby increasing overall resistance and lowering the electrode density. Conversely, if the amount is too small, it is difficult to form a continuous primary coating layer.

The present invention is not limited to the above embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains, other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that it can be implemented with Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects.

Claims (7)

Preparing a positive electrode active material powder;
Coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte;
Performing any one or more of primary polymerization and crosslinking of a material containing the coated polymer electrolyte monomer to obtain a positive electrode active material powder coated with a polymer;
Positioning the positive electrode active material coated with the polymer on a current collector;
Injecting a material containing a second polymer electrolyte monomer into the current collector; And
Secondary polymerization of a material containing the second polymer electrolyte monomer;
Including,
The first polymer electrolyte monomer and the second polymer electrolyte monomer are of the same type, a method of manufacturing a composite positive electrode for a solid lithium ion battery.
The method of claim 1,
The material containing the monomer is a monomer, a method for producing a composite positive electrode for a solid lithium ion battery.
The method of claim 1,
The material containing the monomer is a liquid, a method of manufacturing a composite positive electrode for a solid lithium ion battery.
The method of claim 2,
The monomer is solid lithium containing one selected from polyethylene glycol (PEO), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol diacrylate (PPGDA), polypropylene glycol dimethacrylate (PPGMA), and combinations thereof. A method of manufacturing a composite positive electrode for an ion battery.
The method of claim 1,
Coating the surface of the positive electrode active material powder with a material containing a monomer for a first polymer electrolyte; And
Injecting a material containing a second polymer electrolyte monomer into the current collector;
A method for manufacturing a composite positive electrode for a solid-state lithium ion battery in which a material containing the monomer and a lithium salt are coated or injected together.
The method of claim 5,
The lithium salt is, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ CO ₂ , LiSbF ₆ , _{LiAlCl 4} , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiSCN, 1 selected from LiC(CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carboxylic acid, lithium 4-phenyl borate, imide, and combinations thereof Method for producing a composite positive electrode for solid-state lithium ion batteries containing species.
The method of claim 1,
Coating the surface of the positive electrode active material powder with a material including a monomer for a first polymer electrolyte; In,
A method of manufacturing a composite positive electrode for a solid-state lithium ion battery in which the amount of the material containing the monomer relative to the positive electrode active material powder is 0.1 to 20% by weight.

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