KR20240038368A - Electrode protective layer and battery including the same - Google Patents

Abstract

Disclosed herein are lignin-containing compounds; metal salt; and binder; It relates to an electrode protective layer containing.

Description

Electrode protective layer and battery including the same {ELECTRODE PROTECTIVE LAYER AND BATTERY INCLUDING THE SAME}

The present application relates to an electrode protective layer and a battery including the same.

Recently, with the rapid development in the field of portable electronic devices and electric vehicles, the miniaturization, weight reduction, and high performance of electronic products and communication devices are rapidly progressing, and there is a demand for secondary batteries with high energy density that can be used as a power source for these products. It's getting bigger.

Among these secondary batteries, lithium-metal batteries that use metal materials as cathode active materials are known as promising next-generation battery candidates with high energy density due to the low density of lithium metal and high theoretical capacity (3860 mAh/g). However, when charging and discharging a lithium-metal battery, side reactions that occur between the highly reactive lithium and the electrolyte can create an unstable SEI layer and result in low coulombic efficiency. In addition, due to non-uniform lithium electrodeposition, it grows into a dendrite and pierces the separator, causing a short circuit, which has the limitation of low safety. To prevent this phenomenon, research is being conducted on additives that can be used to manufacture lithium metal batteries.

Korean Patent Publication No. 10-2022-0091505, which is the background technology of this application, is about a lithium metal anode and a method of manufacturing the same.

The purpose of the present application is to solve the problems of the prior art described above and to provide an electrode protective layer containing a lignin-containing compound extracted from waste wood and a method for manufacturing the same.

Additionally, the present application aims to provide an electrode structure including the electrode protection layer, and a secondary battery including the electrode structure.

However, the technical challenges sought to be achieved by the embodiments of the present application are not limited to the technical challenges described above, and other technical challenges may exist.

As a technical means for achieving the above-mentioned technical problem, the first aspect of the present application is a lignin-containing compound; metal salt; and binder; It provides an electrode protective layer containing.

According to one embodiment of the present application, the lignin-containing compound may be extracted from waste wood, but is not limited thereto.

According to one embodiment of the present application, the lignin-containing compound may include lignin and a functional group selected from the group consisting of a sulfonate group, an amine group, and combinations thereof. It is not limited.

According to one embodiment of the present application, the binder is polyvinylpyrrolidone (PVP), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polyethylene amine, and these. It may include, but is not limited to, those selected from the group consisting of combinations.

In addition, the second aspect of the present application is an electrode material; and an electrode protective layer according to the first aspect. It provides an electrode structure comprising a.

According to one embodiment of the present application, the electrode protective layer may have a porous structure, but is not limited thereto.

According to one embodiment of the present application, the electrode material is Cu, Li, Na, K, Rb, Cs, Ni, Co, Sc, Ti, V, Cr, Mn, Fe, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Ag, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, It may include, but is not limited to, those selected from the group consisting of Ho, Er, Tm, Yb, Lu, and combinations thereof.

In addition, a third aspect of the present application includes a first electrode including the electrode structure according to the second aspect, a second electrode disposed opposite the first electrode and including a metal; and an electrolyte filled between the first electrode and the second electrode; It provides a secondary battery comprising a.

According to one embodiment of the present application, during charging and discharging of the secondary battery, ions of the metal may be electrodeposited on the first electrode through the electrolyte, but are not limited thereto.

According to one embodiment of the present application, the metal may be electrodeposited between the electrode protection layer and the electrode material, but is not limited thereto.

According to one embodiment of the present application, the electrode protection layer can control the growth direction of ions electrodeposited on the electrode material, but is not limited thereto.

According to one embodiment of the present application, the electrode protection layer may suppress dendrite generation due to the ions, but is not limited thereto.

According to one embodiment of the present application, the metal may include one selected from the group consisting of Li, Na, K, Rb, Cs, and combinations thereof, but is not limited thereto.

The above-described means of solving the problem are merely illustrative and should not be construed as intended to limit the present application. In addition to the exemplary embodiments described above, additional embodiments may be present in the drawings and detailed description of the invention.

In general, when charging and discharging a lithium-metal battery, there is a problem that lithium is not uniformly deposited and dendrites are generated, resulting in rapid performance deterioration.

In order to solve these problems of the prior art, the electrode protective layer according to the present invention is extracted from waste wood, and contains lignosulfonic acid sodium salt having affinity for lithium, a sulfonate group, And using an amine group, uniform electrodeposition of lithium ions can be induced.

In addition, the electrode protective layer according to the present application enables rapid ion transfer and effective ion exchange through the lignosulfonic acid-sodium salt, amine group, and sulfonate group. Through this, the electrode protection layer suppresses the growth of lithium dendrites and enables stable charging and discharging, thereby providing an improved electrochemical battery.

However, the effects that can be obtained herein are not limited to the effects described above, and other effects may exist.

Figure 1a is a schematic diagram of the effect of an electrode protective layer according to an embodiment of the present application.
Figure 1b is a schematic diagram of the effect of an electrode protective layer according to an embodiment of the present application.
Figure 1c is a schematic diagram of the effect of an electrode protective layer according to an embodiment of the present application.
Figure 2a is an SEM image of an electrode protective layer according to an embodiment of the present application.
Figure 2b is an SEM image of an electrode protective layer according to an embodiment of the present application.
Figure 2c is an SEM image of an electrode protective layer according to an embodiment of the present application.
Figure 3a is an SEM image of an electrode protective layer according to a comparative example of the present application.
Figure 3b is an SEM image of an electrode protective layer according to a comparative example of the present application.
Figure 3c is an SEM image of an electrode protective layer according to a comparative example of the present application.
Figure 4a is an SEM image of an electrode protective layer according to a comparative example of the present application.
Figure 4b is an SEM image of an electrode protective layer according to a comparative example of the present application.
Figure 4c is an SEM image of an electrode protective layer according to a comparative example of the present application.
Figure 5 is a graph of the coulombic efficiency of a battery according to an example and a comparative example of the present application.
6A to 6D are graphs showing electrical properties of a battery according to an embodiment of the present application.

Below, with reference to the attached drawings, embodiments of the present application will be described in detail so that those skilled in the art can easily implement them.

However, the present application may be implemented in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present application in the drawings, parts that are not related to the description are omitted, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout this specification, when a part is said to be “connected” to another part, this includes not only the case where it is “directly connected,” but also the case where it is “electrically connected” with another element in between. do

Throughout this specification, when a member is said to be located “on”, “above”, “at the top”, “below”, “at the bottom”, or “at the bottom” of another member, this means that a member is located on another member. This includes not only cases where they are in contact, but also cases where another member exists between two members.

Throughout the specification of the present application, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components unless specifically stated to the contrary.

As used herein, the terms “about,” “substantially,” and the like are used to mean at or close to a numerical value when manufacturing and material tolerances inherent in the stated meaning are presented, and to aid understanding of the present application. It is used to prevent unscrupulous infringers from unfairly exploiting disclosures in which precise or absolute figures are mentioned. Additionally, throughout the specification herein, “a step of” or “a step of” does not mean “a step for.”

Throughout this specification, the term "combination thereof" included in the Markushi format expression means a mixture or combination of one or more components selected from the group consisting of the components described in the Markushi format expression, It means including one or more selected from the group consisting of.

Throughout this specification, description of “A and/or B” means “A or B, or A and B.”

Hereinafter, the electrode protective layer of the present application and the battery including the same will be described in detail with reference to implementation examples, examples, and drawings. However, the present application is not limited to these embodiments, examples, and drawings.

As a technical means for achieving the above-mentioned technical problem, the first aspect of the present application is a lignin-containing compound; metal salt; and binder; It provides an electrode protective layer containing.

The electrode protective layer according to the present disclosure can be used in lithium-metal batteries.

The lithium-metal battery according to the present application replaces graphite or silicon, which is an anode material of a lithium ion battery, with lithium metal, and can have a higher energy density than a conventional lithium ion battery. However, during the charging process of lithium-metal batteries, lithium ions precipitate on the surface of the anode or cathode and dendrites are formed. These dendrites damage the separator of the battery and hinder the movement of lithium ions, thereby damaging the battery. There is a problem that reduces lifespan and stability.

To prevent this problem, the growth of dendrites can be suppressed or the dendrites can be controlled to grow as uniformly as possible by forming an electrode protective layer on the anode or cathode surface of the lithium-metal battery. To this end, the electrode protective layer according to the present disclosure may include a lignin-containing compound.

According to one embodiment of the present application, the lignin-containing compound may be extracted from waste wood, but is not limited thereto.

According to one embodiment of the present application, the lignin-containing compound may include lignin and a functional group selected from the group consisting of a sulfonate group, an amine group, and combinations thereof. It is not limited.

Lignin according to the present application refers to a fat-soluble phenol polymer among the components constituting the xylem part of wood, and the unit structure of C ₁₈ H ₂₄ O ₁₁ to C ₄₀ H ₄₅ O ₁₈ is repeated, and the unit structure includes hydroxyl group and methoxyl group as functional groups. It refers to a substance that can contain various functional groups such as group, sulfonate group, and amine group.

The electrode protective layer according to the present disclosure includes lignin containing a sulfonate group and/or an amine group as a functional group, and can control the growth of lithium dendrites through the lignin. At this time, functional groups such as the sulfonate group and/or amine group have good affinity for lithium ions and control the electrodeposition position of lithium ions to induce uniform electrodeposition of lithium ions and suppress the formation or growth of dendrites. You can.

At this time, when lignin containing both a sulfonate group and an amine group is used as an electrode protective layer, abundant defect sites are formed, improving electrical conductivity and compensating for the low electrical conductivity of kraft lignin. there is.

In addition, since the electrode protective layer according to the present application is manufactured by extracting lignin from discarded waste wood, the electrode protective layer can be manufactured in an environmentally friendly manner in terms of recycling of resources.

As will be described later, the electrode protective layer is disposed between the electrode to be protected and the electrolyte, and lithium ions can pass through the protective layer.

Specifically, the electrode protection layer has a porous structure, allowing lithium ions to move during charging and discharging. In addition, lithium dendrites have the problem of damaging the separator and causing a short circuit, but the electrode protection layer can function as a physical protective film to prevent lithium dendrites generated during the charging and discharging process from passing through the separator. .

According to one embodiment of the present application, the binder is polyvinylpyrrolidone (PVP), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polyethylene amine, and these. It may include, but is not limited to, those selected from the group consisting of combinations.

In addition, the second aspect of the present application is an electrode material; and an electrode protective layer according to the first aspect. It provides an electrode structure comprising a. As will be described later, the electrode structure can be used as an anode.

According to one embodiment of the present application, the electrode protective layer may have a porous structure, but is not limited thereto.

According to one embodiment of the present application, the electrode material is Cu, Li, Na, K, Rb, Cs, Ni, Co, Sc, Ti, V, Cr, Mn, Fe, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Ag, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, It may include, but is not limited to, those selected from the group consisting of Ho, Er, Tm, Yb, Lu, and combinations thereof.

The electrode material may function as a material that collects current in a secondary battery, which will be described later. For example, the electrode material may include copper foil.

In addition, a third aspect of the present application includes an anode including a metal and an electrode structure according to the second aspect, a cathode disposed opposite the anode and including an electrode active material; and an electrolyte filled between the anode and the cathode; It provides a secondary battery comprising a.

At this time, the electrode structure includes an electrode protective layer according to the first aspect, and the electrode protective layer is disposed on the anode. However, an electrode protection layer may not be disposed on the cathode, but may be disposed as needed.

In this regard, the secondary battery according to the present application may refer to a lithium-metal battery.

According to one embodiment of the present application, the metal may include one selected from the group consisting of Li, Na, K, Rb, Cs, and combinations thereof, but is not limited thereto. Preferably, the metal of the anode may include Li.

For example, the anode may include a lithium metal electrode and an electrode structure disposed on the lithium metal electrode and including copper foil and an electrode protection layer formed on the copper foil.

According to one embodiment of the present application, the electrode active material may include a material selected from the group consisting of Li ⁺ O, LiMn ₂ O ₄ , LiFePO ₄ , LiMnO ₂ , LiCoO ₂ , and combinations thereof, but is limited thereto. no.

In this regard, both the anode and the cathode may include Li, but the anode includes Li metal and the cathode includes Li ions, such as Li ⁺ O, LiMn ₂ O ₄ , LiFePO ₄ , LiMnO ₂ , etc. Contains compounds.

As described above, the electrode structure may be disposed on the surface of the anode, and Li ions may move between the anode and the cathode during charging and discharging of the secondary battery. At this time, the lithium ions can pass through the electrode structure and can be reduced at the anode during charging.

Generally, reduced lithium ions grow in dendrites on the surface of the metal of the anode and form dendrites, which may damage the separator of the secondary battery. However, the electrode structure according to the present application includes the electrode protection layer and protects the electrode. The layer includes a lignin-containing compound, and the lithium ion-friendly nature of the lignin-containing compound can be used to control the lithium dendrites to be uniformly formed on the metal surface of the anode.

According to one embodiment of the present application, during charging and discharging of the secondary battery, ions of the metal may be electrodeposited on the anode through the electrolyte, but are not limited thereto.

1A to 1C are schematic diagrams of the effect of an electrode protective layer according to an embodiment of the present application. Specifically, FIGS. 1A to 1C show copper foil as an electrode material, where FIG. 1A shows only the electrode material, FIG. 1B includes kraft lignin without a functional group, and FIG. 1C shows lignin containing lignin according to the present application. It includes an electrode protective layer containing a compound.

According to one embodiment of the present application, the metal may be electrodeposited between the electrode protection layer and the electrode material, but is not limited thereto.

When the secondary battery is discharged, the metal is eluted as ions and may head to the cathode. At this time, when the secondary battery is charged, metal ions directed to the cathode may be directed to the anode. At this time, the metal ions may pass through the electrode protective layer and be reduced and electrodeposited into metal at a point between the electrode material and the electrode protective layer.

According to one embodiment of the present application, the electrode protection layer can control the growth direction of ions electrodeposited on the electrode material, but is not limited thereto.

According to one embodiment of the present application, the electrode protection layer may suppress dendrite generation due to the ions, but is not limited thereto. The dendrite grows from the anode or cathode and can damage the separator between the electrolyte and the anode or the electrolyte and the cathode, causing a decrease in battery performance.

Referring to FIGS. 1A to 1C, when using an electrode protective layer containing the lignin-containing compound, a uniform lithium metal layer can be formed by electrodepositing lithium ions between the electrode protective layer and the copper foil, but only the electrode material is used. Alternatively, when kraft lignin is used, it can be confirmed that lithium dendrites are formed on the surface of the copper foil.

The present invention will be described in more detail through the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

[Example 1]

A slurry was prepared by mixing Lignin-SO ₃ H, a binder, and a dispersant, and then a protective layer was prepared using the slurry. Next, a 2032 coin cell was manufactured by coating the protective layer on Cu foil.

[Example 2]

A slurry was prepared by mixing Lignin-NH₂ (amine group), a binder, and a dispersant, and then a protective layer was prepared using the slurry. Next, a 2032 coin cell was manufactured by coating the protective layer on Cu foil.

[Example 3]

Lignin-NH ₂ /SO ₃ H, a binder, and a dispersant were mixed to prepare a slurry, and then a protective layer was prepared using the slurry. Next, a 2032 coin cell was manufactured by coating the protective layer on Cu foil.

At this time, Lignin-NH ₂ /SO ₃ H refers to lignin having both NH ₂ groups and SO ₃ H groups.

[Comparative Example 1]

A coin cell was manufactured in the same manner as in Example 1, except that kraft lignin containing no functional group was used instead of lignin sulfonic acid-sodium salt.

[Comparative Example 2]

A coin cell was manufactured in the same manner as in Example 1, except that only Cu foil was used without a protective layer.

[Experimental Example 1]

2A to 4C are SEM images of protective layers according to an example and a comparative example of the present application. Specifically, FIGS. 2A to 2C show the surface of the protective layer according to Example 1, the lithium electrodeposition surface after 10 cycles, and the lithium electrodeposition surface after 100 cycles, and FIGS. 3A to 3C show the protective layer according to Comparative Example 1. surface, the lithium electrodeposition surface after 10 cycles, and the lithium electrodeposition surface after 100 cycles, and Figures 4A to 4C show the surface of the protective layer according to Comparative Example 2, the lithium electrodeposition surface after 10 cycles, and the lithium electrodeposition surface after 100 cycles. . At this time, the cycle means repeated charging and discharging of the coin cells according to Example 1, Comparative Example 1, and Comparative Example 2.

Referring to FIGS. 2A to 4C, the protective layer according to Example 1 has a rougher surface than the protective layers according to Comparative Examples 1 and 2 in the initial state without charging or discharging. However, when comparing the surface after performing 10 or 100 charge/discharge cycles, the protective layer according to Example 1 showed little surface change, but the protective layer according to Comparative Examples 1 and 2 showed severe surface change, forming lithium dendrites. It can be confirmed that multiple occurrences occurred.

[Experimental Example 2]

Figure 5 is a graph of the coulombic efficiency of a battery according to an example and a comparative example of the present application.

Referring to FIG. 5, the coulomb efficiency of the coin cell according to Comparative Examples 1 and 2 decreases from 140 to 160 cycles, while the coulomb efficiency of the coin cell according to Example 1 (Lignin-SO ₃₎ decreases from 140 to 160 cycles. It can be confirmed that there is no change in coulombic efficiency even after 220 cycles (including H).

[Experimental Example 3]

The coulombic efficiency and voltage-areal capacity of the battery according to Example 2 and the battery according to Example 3 were analyzed.

6A to 6D are graphs showing the electrical properties of the battery according to the above example. Specifically, FIGS. 6A and 6B show a battery according to Example 2, and FIGS. 6C and 6D show a battery according to Example 3.

Referring to FIGS. 6A to 6D, the battery according to Example 2 (using Lignin-NH ₂ ) and the battery according to Example 3 (using Lignin-NH ₂ /SO ₃ H) are stable even after 140 cycles. It can be confirmed that it has electrical properties, and through this, it can be confirmed that the formation of dendrites has been suppressed.

In addition, Lignin-NH ₂ /SO ₃ H has stable coulombic efficiency, and it can be confirmed that the reaction occurs stably by confirming the reformation of the plateau section.

The description of the present application described above is for illustrative purposes, and those skilled in the art will understand that the present application can be easily modified into other specific forms without changing its technical idea or essential features. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present application.

Claims (14)

lignin-containing compounds;
metal salt; and
bookbinder;
Including,
Electrode protective layer.
According to claim 1,
The lignin-containing compound is an electrode protective layer extracted from waste wood.
According to claim 1,
The electrode protection layer, wherein the lignin-containing compound includes lignin and a functional group selected from the group consisting of a sulfonate group, an amine group, and combinations thereof.
According to claim 1,
The electrode protective layer wherein the metal salt includes one selected from the group consisting of Na, Li, K, Rb, Cs, and combinations thereof.
According to claim 1,
The binder is selected from the group consisting of polyvinylpyrrolidone (PVP), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polyethylene amine, and combinations thereof. Containing an electrode protective layer.
electrode material; and
The electrode protective layer according to any one of claims 1 to 5;
Including,
Electrode structure.
According to claim 6,
An electrode structure wherein the electrode protective layer has a porous structure.
According to claim 6,
The electrode materials include Cu, Li, Na, K, Rb, Cs, Ni, Co, Sc, Ti, V, Cr, Mn, Fe, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Ag, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, An electrode structure comprising one selected from the group consisting of Lu, and combinations thereof.
A first electrode comprising the electrode structure according to claim 6;
a second electrode disposed opposite the first electrode and containing metal; and
Electrolyte filled between the first electrode and the second electrode;
which includes,
Secondary battery.
According to clause 9,
In the process of charging and discharging the secondary battery, ions of the metal are electrodeposited on the first electrode through the electrolyte.
According to claim 10,
A secondary battery in which the metal is electrodeposited between the electrode protective layer and the electrode material.
According to claim 10,
A secondary battery, wherein the electrode protection layer controls the growth direction of ions electrodeposited on the electrode material.
According to claim 12,
The electrode protection layer is a secondary battery that suppresses the generation of dendrites due to the ions.
According to clause 9,
A secondary battery wherein the metal includes one selected from the group consisting of Li, Na, K, Rb, Cs, and combinations thereof.