KR101830254B1 - Protection layer for secondary cell battery cathode and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a protective layer for a secondary battery positive electrode and a manufacturing method of the same. The present invention relates to an ultra-thin oxide semiconductor technology capable of suppressing stability decrease and improving efficiency characteristics of an existing secondary battery positive electrode due to charging and discharging by applying an Al(2/3)xZnxO protective layer disposed on the secondary battery positive electrode.

Description

     BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a protective layer for a secondary battery,

The present invention relates to a protective layer for a positive electrode of a secondary battery and a method of manufacturing the same.

The secondary battery is a battery that converts chemical energy into electrical energy to supply power to an external circuit, and when discharged, is supplied with external power and converts electrical energy into chemical energy to store electricity.

The rechargeable battery is divided into a nickel battery, an ion battery, a lithium ion battery, a polymer battery, a lithium polymer battery, and a lithium sulfide battery depending on what is used as a charging material.

Lithium-ion batteries currently account for the majority of the secondary battery market, where organic electrolytes are placed between the positive and negative electrodes to repeatedly charge and discharge. It is lighter in weight, and is advantageous in making a high capacity battery, and is widely used in mobile phones and the like. Lithium polymer batteries are a step forward in lithium-ion batteries. They use an electrolyte made of a solid or gel polymer material between the anode and cathode to generate electricity. It has the advantage of being able to vary the shape and making the thinnest battery ever developed.

Conventional secondary battery positive electrode materials have performance and life degradation on the surface of the positive electrode material as the charge and discharge cycles are repeated. In order to solve this problem, a protective layer capable of protecting the surface of the cathode material is applied to suppress the performance degradation due to the charge / discharge cycle.

Conventional secondary battery anode material protection layer technology is based on an oxide having no electric conduction characteristic and thus has a disadvantage in that the electrical characteristics of the anode are deteriorated. In addition, when the atomic layer deposition process is applied, the range of the cathode material is limited, and thus there is a limit in securing the optimum cathode material performance.

Korean Patent Laid-Open Publication No. 10-2014-0107833

SUMMARY OF THE INVENTION The object of the present invention is to provide a protective layer of a secondary battery positive electrode comprising Al _{(2/3) x} Zn _x O

To thereby prevent deterioration of stability in accordance with charge / discharge cycles of the anode and to improve efficiency characteristics, and a method for producing the same.

The secondary battery positive electrode protective layer according to an embodiment of the present invention is characterized by being represented by the following Formula 1 disposed on the secondary battery positive electrode:

≪ Formula 1 >

Al _{(2/3) x} Zn _x O

(Wherein x is a glass number of 0.05 to 0.2).

The thickness of the protective layer may be 1 to 10 nm.

In addition, the active material for the anode may be one selected from the group consisting of NMC, LCO, LMO, and LFP.

The method for manufacturing a protective layer for a secondary battery anode according to an embodiment of the present invention includes: a step (step 1) of depositing a zinc oxide on a secondary battery anode; And doping the zinc oxide with aluminum (step 2); .

The demand for electric vehicles and next-generation large energy storage devices as well as small-sized electronic devices such as mobile phones and notebooks has been rapidly increasing, and development of large-capacity secondary batteries capable of storing energy surplus and being used as needed has been actively developed.

The protection layer for a secondary battery anode and the method for manufacturing the same according to an embodiment of the present invention can increase the initial capacity and capacity retention ratio of the secondary battery by adding aluminum oxide to zinc oxide instead of simple zinc oxide as a protection layer material.

Also, unlike the conventional protective layer, the electrical characteristics and the physical characteristics can be variously adjusted according to the composition ratio of Al _{(2/3) x} Zn _x O, so that it is possible to form a protective layer suitable for the performance of the cathode material.

In addition, since the material properties of the protective layer can be precisely controlled and the protective layer can be uniformly formed on any surface of the cathode material, it can be utilized for improving the performance of various cathode materials used in various kinds of batteries.

In addition, compared with the secondary battery without the positive electrode protection layer, it is possible to suppress the performance and the deterioration of the lifetime as the charge / discharge cycle is repeated.

1 is a view illustrating a secondary battery anode including a protective layer according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements. In the drawings, like reference numerals are used throughout the drawings. In addition, "including" an element throughout the specification does not exclude other elements unless specifically stated to the contrary.

Protective layer for secondary battery anode (SECONDARY CELL BATTERY CATHODE)

As the charge and discharge cycles of the secondary battery are repeated, the lithium secondary phase is irreversibly formed on the surface of the cathode material, resulting in deterioration of performance and service life. In order to solve this problem, a technique has been developed in which a protective layer capable of protecting the surface of a cathode material of a secondary battery is applied to suppress performance deterioration due to charge / discharge cycles. Conventionally, since the material of the protective layer for the secondary battery anode is based on an oxide having no electric conduction characteristic, the electrical properties of the anode are deteriorated and the range of materials for the ALD (Atomic Layer Deposition) There is a limit to securing material performance.

The protective layer for an anode of a secondary battery according to the present invention can be formed by applying an ultra-thin Al _{(2/3) x} Zn _x O oxide by atomic layer deposition, chemical vapor deposition, sputtering, .

In addition, since the Al _{(2/3) x} Zn _x O oxide can control various electrical characteristics and physical properties according to the composition ratio, it is possible to form a protective layer suitable for the performance of the cathode material. In addition, the atomic layer deposition process can uniformly form a protective layer on the surface of the cathode material having any structure.

By utilizing the protection layer technology for a secondary battery anode according to the present invention, it is possible to minimize irreversible formation of lithium secondary phase of a cathode material in accordance with the charging / discharging cycle of the secondary battery while minimizing electrical performance deterioration, Possible new anode materials are possible.

The active material for the positive electrode may be any one of NCM, LCO, LMO, and LFP, and is not particularly limited. The NCM represents the formula of Li [NiCoMn] O2, and the LCO represents the formula of LiCoO2. The LMO represents a chemical formula of LiMn2O4, and LFP represents a chemical formula of LiFePO4 / C.

The thickness of the protective layer for a secondary battery positive electrode according to the present invention is preferably in the range of 1 nm to 10 nm. When the thickness is less than 1 nm, the thickness of the protective layer is too small to function as a protective layer for the positive electrode, and when the thickness exceeds 10 nm, the thickness of the protective layer is too thick, There is a problem that an insulating layer is formed.

The secondary battery positive electrode protective layer according to the present invention has an advantage that the initial capacity and the capacity retention ratio of the secondary battery including the positive electrode active material can be improved at the same time by using the material represented by the above formula (1).

The present invention also provides a secondary battery including the protective layer. Since the secondary battery according to the present invention includes the positive electrode protective layer according to the present invention on the positive electrode, deterioration of performance at the surface of the positive electrode during charging and discharging is suppressed, thereby improving the initial capacity and the capacity retention rate simultaneously .

Further, the present invention provides a method of manufacturing a secondary battery comprising the steps of: (1) depositing zinc oxide on a secondary battery anode; And doping the zinc oxide with aluminum (step 2); The positive electrode active material layer and the negative electrode active material layer.

Hereinafter, the present invention will be described in detail for each step.

Step 1 according to the present invention is a step of depositing a zinc oxide on the anode of a secondary battery and forming a zinc oxide layer as a base of the protective layer on the anode of the secondary battery. At this time, the step of depositing the zinc oxide may be performed by one method selected from the group consisting of atomic layer deposition, chemical vapor deposition, and sputtering, and more preferably, atomic layer deposition is performed.

Next, Step 2 according to the present invention is a step of doping aluminum oxide on the deposited zinc oxide, replacing part of the zinc element of the zinc oxide layer with aluminum. At this time, the step 2 may be performed by one method selected from the group consisting of atomic layer deposition, chemical vapor deposition and sputtering, more preferably atomic layer deposition, and aluminum oxide The aluminum oxide can be doped into the zinc oxide.

The steps 1 and 2 according to the present invention are preferably carried out so that the thickness of the protective layer is 1 nm to 10 nm. When the thickness is less than 1 nm, the thickness of the protective layer is too small to function as a protective layer for the positive electrode. When the thickness exceeds 10 nm, the thickness of the protective layer is too thick, There is a problem that it becomes a layer.

The method for manufacturing a protective layer for a secondary battery positive electrode according to the present invention can improve the initial capacity and the capacity retention rate of the secondary battery including the zinc oxide protective layer doped with aluminum on the positive electrode, The composition and thickness can be easily controlled, and it is easy to appropriately adjust the effect according to the situation.

Hereinafter, the structure and technical characteristics of the secondary battery positive electrode protective layer according to the present invention will be described in detail with reference to the preferred embodiments. However, it should be understood that the present invention is not limited thereto.

Example

Example 1: x = 0.0487 in Al _{(2/3) x} Zn _x O

Diethylzinc (DEZn) was deposited on the anode substrate by an atomic layer deposition process and water (H ₂ O) was introduced as a reactant to form a zinc oxide layer. Thereafter, Trimethyl aluminum (TMA) was deposited by an atomic layer deposition process, and water (H ₂ O) was introduced as a reactant to dope zinc oxide with aluminum to prepare a protective layer 1 for a secondary battery anode. At this time, the thickness of the protective layer 1 was 1.4 nm.

Example 2: x = 0.095 in Al _{(2/3) x} Zn _x O

The protective layer 2 for a secondary battery positive electrode was prepared in the same manner as in Example 1, except that the thickness was adjusted to be x = 0.095 in Example 1. At this time, the thickness of the protective layer 2 was 3 nm.

Example 3: x = 0.1818 in Al _{(2/3) x} Zn _x O

The protective layer 3 for a secondary battery positive electrode was prepared in the same manner as in Example 1, except that the thickness was adjusted to be x = 0.1818 in Example 1. At this time, the thickness of the protective layer 3 was 5.7 nm.

Example 4: Two cycles with x = 0.1818 in Al _{(2/3) x} Zn _x O

The protective layer 4 for a secondary battery positive electrode was prepared in the same manner as in Example 1, except that the thickness was adjusted to be x = 0.1818 in Example 1, and that the thickness was adjusted to be 2 cycles. At this time, the thickness of the protective layer 4 was 9.2 nm.

Example 5

A lithium secondary battery was prepared by a known method. At this time, the positive electrode protective layer 1 prepared in Example 1 was formed on the positive electrode to prepare a secondary battery 1.

Example 6

A lithium secondary battery was prepared by a known method. At this time, the positive electrode protective layer 2 prepared in Example 2 was formed on the positive electrode to prepare a secondary battery 2.

Example 7

A lithium secondary battery was fabricated by a known method. At this time, the positive electrode protective layer 3 prepared in Example 3 was formed on the positive electrode to prepare a secondary battery 3.

Example 8

A lithium secondary battery was prepared by a known method. At this time, the positive electrode protective layer 4 prepared in Example 4 was formed on the positive electrode to prepare a secondary battery 4.

Comparative Example 1

The protective layer 5 for a secondary battery positive electrode was prepared in the same manner as in Example 1, except that the protective layer material was ZnO instead of Al _{(2/3) x} Zn _x O. At this time, the thickness of the protective layer 5 was 5.5 nm.

Comparative Example 2

The secondary battery 5 was prepared by forming the positive electrode protective layer 5 prepared in Comparative Example 1 on the positive electrode.

Comparative Example 3

A lithium secondary battery was prepared by a known method, and a secondary battery 6 was prepared without a protective layer for a positive electrode.

<Experimental Example>

The following experiments were conducted to confirm the charging and discharging characteristics of the secondary batteries manufactured by the examples and comparative examples of the present invention.

Charge-discharge characteristics of the secondary batteries manufactured by Examples 5 to 8 and Comparative Examples 2 and 3 of the present invention were measured by a battery charge / discharge tester. The results are shown in Table 1 below.

x ( Al _{(2/3) x} Zn _x O ) Example 5 Example 6 Example 7 Example 8 Comparative Example 2 Comparative Example 3 Protective layer thickness (nm) 1.4 3 5.7 9.2 5.5 - Initial capacity ( mAh / g) 165 170 172 167 173 176 After 50 cycles  Volume
( mAh / g) 145 149 151 147 130 107 Capacity retention rate ( % ) 87.9 87.7 87.8 88.0 75.1 60.7

According to Table 1, the thickness and the initial capacity of the protective layer, the capacity after 50 cycles and the capacity retention ratio are changed in accordance with the adjustment of x in Al _{(2/3) x} Zn _x O as the protective layer material for the secondary battery anode Able to know.

When x is 0.0487, the thickness of the protective layer is 1.4 nm, the initial capacity of the secondary battery is 165 mAh / g, the capacity after 150 cycles is 145 mAh / g, and the capacity retention rate is 87.9%.

When x is 0095, the thickness of the protective layer is 3 nm, the initial capacity of the secondary battery is 170 mAh / g, the capacity after 149 cycles is 149 mAh / g, and the capacity retention rate is 87.7%.

When x is 0.1818, the thickness of the protective layer is 5.7 nm, the initial capacity of the secondary battery is 172 mAh / g, the capacity after 150 cycles is 151 mAh / g, and the capacity retention rate is 87.8%.

When x is 0.1818, the thickness of the protective layer is 9.2 nm after 2 cycles, the initial capacity of the secondary battery is 167 mAh / g, the capacity after 150 cycles is 147 mAh / g, and the capacity retention rate is 88%.

When the protective layer material for the anode was made of ZnO other than Al _{(2/3) x} Zn _x O, the protective layer thickness was 5.5 nm, the initial capacity of the secondary battery was 173 mAh / g, the capacity after 50 cycles was 130 mAh / g, and the capacity retention rate is 75.1%.

This indicates that the initial capacity is larger than that in the case of using Al _{(2/3) x} Zn _x O according to the present invention as a protective layer, but the performance is deteriorated in terms of the capacity retention rate.

In the case where the protective layer for the secondary battery is not applied, the initial capacity of the secondary battery is 176 mAh / g, the capacity after 50 cycles is 107 mAh / g, and the capacity retention rate is 60.7%.

This indicates that the initial capacity is larger than that in the case of using Al _{(2/3) x} Zn _x O according to the embodiment of the present invention as a protective layer, but the performance is deteriorated in terms of the capacity retention rate.

It can be seen from the above that the positive electrode protective layer according to the present invention can simultaneously improve the initial capacity and the capacity retention rate of the secondary battery.

MANUFACTURING METHOD OF PROTECTION LAYER FOR SECONDARY CELL BATTERY CATHODE

The method for manufacturing a protective layer for a cathode for a secondary battery according to an embodiment of the present invention preferably uses an atomic layer deposition (ALD) process capable of uniformly manufacturing a thin thin layer. Alternatively, sputtering and chemical vapor deposition (CVD) ) May also be used. Manufacturing process techniques that can coat thin metal oxide layers do not limit the specific deposition method.

The atomic layer deposition (ALD) process is a nano thin film deposition technique that utilizes the phenomenon of chemically sticking mononuclear layer during the semiconductor manufacturing process. By alternately advancing adsorption and substitution of molecules on the surface of the wafer, -by-layer deposition, the oxide and metal film can be deposited as thin as possible, and the film formed at the lower temperature (less than 500 degrees) than the chemical vapor deposition (CVD) in which the particles formed by the chemical reaction of the gas are deposited on the wafer surface And it is suitable for manufacturing a system-on-chip (SoC).

The CVD (Chemical Vapor Deposition) process is a process of depositing particles formed by a chemical reaction between reaction gases on a wafer surface to form an insulating film or a conductive film. Two or more gases are blown into the same chamber to produce a specific compound, the reactive chemical is deposited uniformly on the wafer, the remaining unwanted chemical reaction products are made into a gas state, And shows the structure to be discharged.

The sputtering process is a kind of vacuum deposition, which generates a plasma at a relatively low degree of vacuum, accelerates a gas such as argon, which is ionized, and collides with a target to eject a target atom, thereby forming a film on the substrate . There are various types of plasma generation methods. The rate of forming the film was small, but it was 100 times larger than that used so far due to the development of the magnetron type target with the magnet placed on the back side of the target. In sputtering of an alloy, there is an advantage that a film can be formed almost in accordance with the composition of the alloy. When reactive gas is used, film formation (reactive sputtering) of reactant with gas is also possible.

As described above, the functions and the embodiments of the respective components are omitted in order to avoid redundant explanations.

The present invention is not limited to the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

100: anode
200: anode protection layer

Claims (9)

Disposed on the secondary battery anode
1. A protective layer for a secondary battery positive electrode, characterized in that the thickness of the protective layer is 1 nm to 10 nm.
&Lt; Formula 1 >
Al _{(2/3) x} Zn _x O
(Wherein x is a glass number of 0.05 to 0.2).
delete The method according to claim 1,
Wherein the active material for the positive electrode is one selected from the group consisting of NCM, LCO, LMO, and LFP.
The method according to claim 1,
Wherein the secondary battery positive electrode protective layer simultaneously improves the initial capacity and the capacity retention rate of the secondary battery.
anode;
cathode; And
Comprising an electrolyte,
And a protective layer for a positive electrode of a secondary battery, the protective layer being disposed on the positive electrode, wherein the thickness of the protective layer is 1 nm to 10 nm.
&Lt; Formula 1 >
Al _{(2/3) x} Zn _x O
(Wherein x is a glass number of 0.05 to 0.2).
Depositing zinc oxide on the secondary battery anode (step 1); And
Doping the zinc oxide with aluminum (step 2); The method of manufacturing a protective layer for a positive electrode of a secondary battery according to claim 1,
Wherein the positive electrode protective layer is represented by the following general formula (1)
Wherein step 1 and step 2 are performed so that the thickness of the protective layer is 1 nm to 10 nm.
Method for producing protective layer for secondary battery anode:
&Lt; Formula 1 >
Al _{(2/3) x} Zn _x O
(Wherein x is a glass number of 0.05 to 0.2).
The method according to claim 6,
Wherein the step 2 is performed by a method of depositing aluminum oxide.
The method according to claim 6,
Wherein the step 1 and the step 2 are performed by one method selected from the group consisting of an atomic layer deposition, a chemical vapor deposition, and a sputtering process.
delete

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