KR20210103243A - Thin film encapsulation for all solid-state batteries and method for fabricating the same - Google Patents

Abstract

In the present specification, provided is a hybrid thin film encapsulation which comprises an organic material layer comprising parylene, and an inorganic layer stacked on the organic material layer. According to the present invention, oxygen and moisture permeation can be prevented.

Description

Thin-film encapsulation and manufacturing method for all-solid-state thin-film secondary batteries {THIN FILM ENCAPSULATION FOR ALL SOLID-STATE BATTERIES AND METHOD FOR FABRICATING THE SAME}

In the present specification, as a thin film-type thin film encapsulation for packaging an all-solid-state thin film secondary battery, it is disclosed with respect to a hybrid type thin film encapsulation.

A thin-film secondary battery refers to a rechargeable battery in which battery components are thinly implemented on a thin-film substrate. The thin film battery has a very thin thickness of 0.1 mm or less and can implement a positive electrode, an electrolyte, and a negative electrode, so it is suitable for use as a power source for thin electronic devices. However, in the thin film secondary battery, the thickness of the encapsulant is thicker or it is difficult to encapsulate the thin film in the form of a thin film compared to the very thin thickness.

In addition, there are currently no patents for thin film encapsulation for all-solid-state thin film batteries. In the case of the patent on thin film encapsulation for thin film cells in Patent Document 1, 15 or more metal layers and nitride layers were alternately deposited to block oxygen and moisture in the atmosphere, but the difficulty in controlling the uniform deposition conditions of the multilayer thin film and the complexity of the process exist.

Accordingly, there is a need for packaging having excellent WVTR and long lifespan characteristics while maintaining a very thin thickness of the thin film secondary battery.

US 8518581 B2

In one aspect of the present invention, while the thin film secondary battery can be implemented with a very thin thickness, the packaging is produced in a pouch type or a housing type, and since the thickness and size of the packaging is larger than that of the thin film secondary battery, the advantages of the thin film battery are utilized. An attempt is made to solve a problem that is difficult to apply to an ultra-small energy storage device.

In addition, in one aspect of the present invention, since the organic thin film has a high water vapor transmission rate (WVTR) characteristic, the production of a multilayer film is unavoidable, and the inorganic thin film alternately deposits a metal layer and a nitride layer in the prior art while repeatedly depositing the process. to solve problems that are vulnerable to defects such as pinholes in

In one embodiment of the present invention in order to achieve the above object, an organic material layer containing parylene (Parylene); and an inorganic material layer laminated on the organic material layer; including, a hybrid thin film encapsulation is provided.

In an exemplary embodiment, the organic material layer may have a thickness of 1 to 10 μm.

In an exemplary embodiment, the inorganic material layer may have a stacked structure including at least one of a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, and a silicon oxide (SiOy) layer.

In an exemplary embodiment, the inorganic material layer may have a structure in which a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, and a silicon oxide (SiOy) layer are sequentially stacked.

In an exemplary embodiment, the silicon nitride (SiNx) layer has a thickness of 100 to 800 nm, the silicon nitride oxide (SiNxOy) layer has a thickness of 3 to 8 nm, and the silicon oxide (SiOy) layer has a thickness of 50 to 200 nm may have a thickness.

In an exemplary embodiment, the thickness of the hybrid thin film encapsulation may be less than 10 μm.

In another embodiment of the present invention, an electrochemical device; and the above-described hybrid thin film encapsulation layered on the electrochemical device, wherein the hybrid thin film encapsulation includes an organic material layer containing parylene and an inorganic material layer stacked on the organic material layer, a secondary battery comprising: is provided

In an exemplary embodiment, the secondary battery may be an all-solid-state thin film secondary battery.

In another embodiment of the present invention, forming an organic material layer containing parylene (Parylene) on the electrochemical device; and forming an inorganic layer on the organic layer.

In an exemplary embodiment, the forming of the inorganic material layer may include depositing a silicon nitride (SiNx) layer; _{Coating a SiO 2} sol (silica sol) on a silicon nitride (SiNx) layer; and _{heat-treating the SiO 2} sol to form a silicon oxide (SiOy) layer and a silicon nitride oxide (SiNxOy) layer between the silicon nitride (SiNx) layer and the silicon oxide (SiOy) layer.

In an exemplary embodiment, the silicon nitride oxide (SiNxOy) layer may be formed by solid-state diffusion of SiNx and SiOy at the interface between the silicon nitride (SiNx) layer and the silicon oxide (SiOy) layer.

Accordingly, the thin film encapsulation for an all-solid-state thin film secondary battery according to an embodiment of the present invention can prevent oxygen and moisture permeation by applying an organic-inorganic hybrid thin film encapsulation including an organic material layer and an inorganic material layer. Through this, all-solid-state thin-film secondary batteries and thin-film encapsulation can be manufactured within tens of micrometers, and accordingly, various micro-devices and various forms will be possible.

1 is a cross-sectional view schematically showing the structure of an all-solid-state thin film secondary battery according to an embodiment of the present invention.
2 shows a cross-sectional structure of a thin film encapsulation for an all-solid-state thin film secondary battery according to an embodiment of the present invention.
3A shows a cross-sectional SEM image of a thin film encapsulation for an all-solid-state thin film secondary battery according to an embodiment of the present invention.
3b shows a cross-sectional TEM image of a thin film encapsulation for an all-solid-state thin film secondary battery according to an embodiment of the present invention.
4a and 4b show the oxidation degree of the Li electrode according to the presence or absence of an organic material layer in a thin film encapsulation for an all-solid-state thin film secondary battery, respectively, showing the case in which there is no parylene organic material layer (Fig. 4a) and the case in which the parylene organic material layer is present (Fig. 4b). do.
Figure 5a shows the results of the charge-discharge graph according to time of the all-solid-state thin-film secondary battery without thin-film encapsulation.
FIG. 5B shows the results of charging and discharging graphs according to time of an all-solid-state thin-film secondary battery encapsulated with only an organic material layer (parylene).
FIG. 5c shows the results of charging and discharging graphs according to time of the all-solid-state thin film secondary battery encapsulated with the hybrid thin film encapsulation according to Example 2 of the present invention.
6A and 6B show the results of measuring the charging and discharging characteristics of the all-solid-state thin film secondary battery encapsulated with the hybrid thin film encapsulation according to Example 2 of the present invention in an atmospheric atmosphere.

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

The embodiments of the present invention disclosed in the text are illustrated for the purpose of explanation only, and the embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in the text. .

The present invention is not intended to limit the present invention to a specific disclosed form, but is not intended to limit the present invention to a specific disclosed form, as various changes may be made and may have various forms, and all changes, equivalents or substitutes included in the spirit and scope of the present invention should be understood as including

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hybrid thin film encapsulation

Accordingly, the present inventors, in one embodiment of the present invention, in order to solve the problems as described above, an organic material layer containing parylene (Parylene); and an inorganic material layer laminated on the organic material layer; including, a hybrid thin film encapsulation.

The hybrid thin film encapsulation for an all-solid-state thin-film secondary battery according to an embodiment of the present invention serves to encapsulate the all-solid-state thin-film secondary battery and isolate it from the external environment. may play a role in preventing

In one embodiment, the organic material layer containing parylene may prevent oxidation of the all-solid-state thin film secondary battery to the SiO _{2 sol solution due to defects such as pinholes during the SiO 2 sol solution dip coating process.} .

In one embodiment, the organic material layer may have a thickness of 1 to 10 μm, preferably 2 to 6 μm. When the thickness of the organic material layer is less than 1 μm, it may be oxidized during the dip coating process, and when the thickness is more than 10 μm, the inorganic layer is not uniformly coated, and WVTR characteristics may be reduced.

In an embodiment, the inorganic material layer may have a stacked structure including at least one of a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, and a silicon oxide (SiOy) layer. For example, the inorganic material layer may have a structure in which a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, and a silicon oxide (SiOy) layer are sequentially stacked. Here, the inorganic layer may play a role such as oxygen permeation and moisture permeation prevention, and in particular, a silicon nitride oxide (SiNxOy) layer may play a decisive role in oxygen permeation and moisture permeation prevention.

However, when only an inorganic material layer including a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, or a silicon oxide (SiOy) layer is applied, defects such as pinholes occur during the _{SiO 2 sol solution dip coating process.} can occur In addition, as shown in FIG. 4 , in the sample without the parylene thin film as the organic material layer, it can be seen that the Li electrode was peeled off while being oxidized and damaged.

Accordingly, the hybrid thin film encapsulation according to an embodiment of the present invention includes an organic material layer including Parylene; and an inorganic material layer laminated on the organic material layer.

In one embodiment, the silicon nitride (SiNx) layer may have a thickness of 100 to 800 nm, preferably 300 to 500 nm, and the silicon nitride oxide (SiNxOy) layer has a thickness of 3 to 8 nm, The silicon oxide (SiOy) layer may have a thickness of 50 to 200 nm, preferably 85 to 120 nm. When the thickness of the silicon nitride (SiNx) layer, the silicon nitride oxide (SiNxOy) layer, and the silicon oxide (SiOy) layer is within the above-mentioned range, the best WVTR characteristic may be exhibited.

In one embodiment, the thickness of the hybrid thin film encapsulation may be less than 15 μm. When the thickness of the hybrid thin film encapsulation exceeds 15 μm, cracks may be formed during the process, and the advantages of thin film encapsulation disappear.

thin film secondary battery

In another embodiment of the present invention, an electrochemical device; and the above-described hybrid thin film encapsulation layered on the electrochemical device, wherein the hybrid thin film encapsulation includes an organic material layer containing parylene and an inorganic material layer stacked on the organic material layer, a secondary battery comprising: is provided

In one embodiment, the secondary battery may be an all-solid-state thin-film secondary battery, for example, an all-solid-state thin-film secondary battery having the structure shown in FIG. 1 . The all-solid-state thin film secondary battery applied in the hybrid thin film encapsulation of the embodiment of the present invention is not particularly limited, and may be specifically as follows:

For example, in the present invention, the all-solid-state thin film secondary battery may include a structure including a positive electrode active material, a negative electrode active material, a solid electrolyte, and a current collector formed on a substrate.

In an embodiment, the substrate may include a flexible substrate in which a polymer material such as polyimide, PET, or PEN and glass or mica are peeled off.

In one embodiment, the positive electrode active material is _{LiCoO 2, LiMnO 2, LiNiO 2} , LiNi x Mn y Co 1 -x- y O 2, LiFePO 4, LiMnPO 4, LiNiPO 4, LiFe 1 - x Mn x PO 4, LiMn It may include a cathode active material for secondary batteries, such as ₂ O _{4 .} In addition, the negative active material may include an anode active material for a secondary battery such as Li, Si, Si-Al, SiN _x , Li ₄ Ti ₅ O _{12 , graphite, carbon nanotubes, or graphene.}

In one embodiment, the solid electrolyte may include a solid electrolyte for a secondary battery, such as _{LiPON, LiBON, or LiLaTiO 3 .}

In one embodiment, the current collector may include a thin film made of Pt, Al, Cu, Ni, or Ni-Cr.

In one embodiment, the thin film battery may be a laminated flexible thin film battery including a positive electrode material, an electrolyte, or a negative electrode material.

Meanwhile, the all-solid-state thin film secondary battery may have a structure in which a current collector, a negative electrode, a solid electrolyte, a positive electrode, and a current collector thin films are sequentially stacked on a flat substrate as described above, wherein the constituent material is, for example, sputtering It may be formed through a deposition process such as In addition, the spheroid material may be deposited using other thin film deposition equipment such as PLD, ALD, evaporator, E-beam, spin-coater, spray-deposition, CVD, PECVD, and the like, but is not limited thereto.

In one embodiment, the hybrid thin film encapsulation according to the present invention encapsulates all of the all-solid-state thin-film secondary batteries in a state in which the all-solid-state thin-film secondary battery in which the deposition process of constituent materials such as cathode material, anode material, solid electrolyte, and current collector has been completed is prepared may have the form

For example, a thin film encapsulation in which parylene, SiNx, SiNxOy, and SiOy are sequentially stacked on an all-solid-state thin film secondary battery in a quadruple-layer structure is presented. SiO ₂ sol (silica sol) is coated on the _{SiNx thin film, and the SiO 2} sol is converted into a SiOy thin film through heat treatment, and the SiNxOy thin film is formed at the interface between the SiNx thin film and the SiOy thin film. It is possible to manufacture a hybrid thin film encapsulation.

Hybrid thin film encapsulation method

In another embodiment of the present invention, forming an organic material layer containing parylene (Parylene) on the electrochemical device; and forming an inorganic layer on the organic layer.

In an embodiment, the forming of the inorganic material layer may include depositing a silicon nitride (SiNx) layer; _{coating a SiO 2} sol (silica sol) on a silicon nitride (SiNx) layer; and _{heat-treating the SiO 2} sol to form a silicon oxide (SiOy) layer and a silicon nitride oxide (SiNxOy) layer between the silicon nitride (SiNx) layer and the silicon oxide (SiOy) layer.

In an embodiment, the silicon nitride oxide (SiNxOy) layer may be formed by solid-state diffusion of SiNx and SiOy at the interface between the silicon nitride (SiNx) layer and the silicon oxide (SiOy) layer. Specifically, the SiNxOy thin film formed at the interface between the SiNx thin film and the SiOy thin film by the solid-state diffusion has a dense tissue structure, and can play a decisive role in preventing oxygen permeation and moisture permeation of the thin film encapsulation.

On the other hand, the SiOy thin film is SiO ₂ sol (silica sol) is converted by heat treatment, the SiNxOy thin film may be formed by solid-state diffusion of SiNx and SiOy during heat treatment.

In an embodiment, the silicon nitride oxide (SiNxOy) layer may be formed through solid-phase diffusion by heat treatment, and specifically may be heat-treated in an atmospheric atmosphere.

For example, the silicon nitride oxide (SiNxOy) layer may be formed by heat treatment at a temperature of 80 to 160 °C, preferably at a temperature of 100 to 140 °C. In addition, the silicon nitride oxide (SiNxOy) layer may be formed by heat treatment for 5 hours to 15 hours, and preferably, heat treatment for 8 hours to 12 hours. When the heat treatment is performed in the above-described temperature and/or time range, the formed SiNxOy thin film has a dense tissue structure, and can play a decisive role in preventing oxygen permeation and moisture permeation of the thin film encapsulation.

Example

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example 1: Preparation of all-solid-state thin film secondary battery

Platinum was used as the anode current collector thin film, and it was deposited through DC sputtering. On the anode thin film, a LiMPO ₄ (M=Fe, Ni, etc.) thin film is deposited using a sputtering method, and then a solid electrolyte such as LiPON is deposited using a sputtering method. A cathode thin film such as Li, SiNx or Li ₄ Ti ₅ O ₁₂ is deposited on the solid electrolyte, and finally, a cathode current collector is deposited using DC sputtering. The details are as follows.

A single-phase target having a composition of LiFePO _{4 was} formed on a polyimide substrate on which platinum was deposited using RF magnetron sputtering (Samwon Vacuum, Korea). The initial vacuum degree before film formation was 5Х10 ^-6 mTorr or less, and a thin film was manufactured at a pressure of 40 mTorr during film formation. The output at the time of film formation was fixed at 160 W (4" target, 2 W/cm2), which was derived as an optimal condition through preliminary experiments. For the crystallization of the thin film, the temperature of the substrate was fixed at room temperature, and then the thin film was manufactured, and the atmosphere was controlled. _{Heat treatment was performed in a reducing atmosphere while injecting 3% H 2} /(Ar+H ₂ ) at a rate of 800 cc/min in an electric furnace capable of this. At this time, the heat treatment temperature was 400° C. and the heat treatment was performed for 2 hours at a temperature increase rate of 3° C./min. , crystallization takes place after heat treatment in an atmosphere furnace.

As the solid electrolyte, a Li ₃ PO ₄ target was used, and a LiPON thin film was formed at room temperature through reactive sputtering using RF magnetron sputtering.

For the cathode, Li metal or SiNx is deposited at room temperature using thermal or e-beam evaporator and sputtering, respectively.

As the cathode current collector thin film, a copper thin film is deposited using DC sputtering at room temperature.

Example 2: Hybrid thin film encapsulation application

The parylene thin film was deposited using a thermal evaporator. On the all-solid-state thin-film secondary battery of Example 1, the parylene source was heated to 150° C. and secondary to 600° C. to vaporize to form a polymer thin film. Then, in a state in which an all-solid-state thin film secondary battery is mounted in a PECVD chamber for SiNx thin film deposition, SiH ₄ , NH ₃ , N ₂ gas is injected into the chamber at 25, 100, and 380 sccm, respectively, and RF power of 400W was applied and the process pressure of 430 mTorr was maintained for 8 minutes to form SiNx with a thickness of about 400 nm on the all-solid-state thin film secondary battery on which parylene was deposited.

Then, in an N ₂ atmosphere, SiO ₂ sol was dip-coated and heat-treated in an oven at a temperature of 120° C. for 10 hours. During _{dip coating of SiO 2} sol, the extraction speed is varied to 0.5 mm/s, 1 mm/s, 3 mm/s, and 5 mm/s, so that the SiO ₂ sol is coated with a thickness of about 40 nm, about 85 nm, about 117 nm, and about 225 nm, respectively. made to be

As shown in the SEM picture of FIG. 3a, it can be confirmed that a SiOy thin film of about 100 nm is formed, and referring to the TEM picture of FIG. Confirmed.

Therefore, it can be confirmed that the thin film encapsulation for an all-solid-state thin film secondary battery of Example 2 is provided by stacking a four-layered thin film in which Parylene, SiNx, SiNxOy, and SiOy are sequentially stacked as shown in FIG. 2 .

Comparative Example 1: Parylene thin film encapsulation application

The parylene thin film was deposited using a thermal evaporator. On the all-solid-state thin-film secondary battery of Example 1, the parylene source was heated to 150° C. and secondary to 600° C. to vaporize to form a polymer thin film. The all-solid-state thin-film secondary battery thus prepared was sealed only with an organic thin film (parylene).

Experimental Example 1: Charge/discharge test

A charge/discharge test according to time of the all-solid-state thin film secondary battery to which the thin film encapsulation according to Examples and Comparative Examples was applied was performed. All samples were measured in air.

5A shows the results of the charge-discharge graph according to time of the all-solid-state thin-film secondary battery without thin-film encapsulation of Example 1. FIG. After 10 minutes of charging, it was confirmed that the potential rapidly increased under the influence of oxidation of the Li anode, and then an open circuit was formed.

FIG. 5b shows the results of charging and discharging graphs according to time of the all-solid-state thin film secondary battery encapsulated only with the organic material layer (parylene) of Comparative Example 1. FIG. For about 6 hours, charging proceeded normally in the first cycle, but oxidation of Li proceeded during discharging, and the voltage flux could be observed. From the second cycle, a voltage plateau at 3.4V could not be observed, and a sudden voltage rise and voltage drop were confirmed. In the 3rd cycle, the effect of Li oxidation was greater and the voltage flux became greater. Also, the complete oxidation of Li could no longer be measured. In the case of the thin film encapsulation sample using SiNx, SiNxOy, and SiOy without parylene, the battery was damaged immediately after the thin film encapsulation process, so charging and discharging could not proceed.

FIG. 5c shows the results of charging and discharging graphs according to time of the all-solid-state thin film secondary battery encapsulated with the hybrid thin film encapsulation of Example 2. FIG. It was confirmed that charging and discharging were stably performed when charging and discharging was performed for 3 or more cycles for about 30 hours, and thus, the long-term stability of the hybrid thin film encapsulation according to the embodiment of the present invention was confirmed.

Experimental Example 2: Long-term stability test

In order to confirm the stability of the thin film encapsulation for the all-solid-state thin-film secondary battery implemented in the present invention, the charging and discharging characteristics of the all-solid-state thin-film secondary battery were measured in the atmosphere.

As shown in Fig. 6a, it was confirmed that the battery was stably driven even when exposed to the air for a long time. As shown in Fig. 6b, the result of electrochemical impedance spectroscopy analysis showed a slight increase to 390 ohm after 1 cycle and 410 ohm after 2 cycles, but slightly increased to 310 ohm after 10 cycles. As a result, the resistance decreased and a metastable state maintaining a saturation value of about 330 ohm after 50-100 cycles was confirmed, confirming that both the electrode and the electrolyte were stably present.

The embodiments of the present invention described above should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can improve and change the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the protection scope of the present invention as long as they are apparent to those of ordinary skill in the art.

Claims (13)

an organic material layer containing parylene; and
A hybrid thin film encapsulation comprising; an inorganic material layer laminated on the organic material layer. According to claim 1,
The organic layer is characterized in that having a thickness of 1 to 10 ㎛, hybrid thin film encapsulation. According to claim 1,
The inorganic material layer is a hybrid thin film encapsulation, characterized in that it has a stacked structure including at least one of a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, and a silicon oxide (SiOy) layer. 4. The method of claim 3,
The inorganic material layer is a hybrid thin film encapsulation, characterized in that it has a structure in which a silicon nitride (SiNx) layer, a silicon nitride oxide (SiNxOy) layer, and a silicon oxide (SiOy) layer are sequentially stacked. 4. The method of claim 3,
The silicon nitride (SiNx) layer has a thickness of 100 to 800 nm, the silicon nitride oxide (SiNxOy) layer has a thickness of 3 to 8 nm, and the silicon oxide (SiOy) layer has a thickness of 50 to 200 nm. which is a hybrid thin film encapsulation. According to claim 1,
The hybrid thin film encapsulation has a thickness of less than 10 μm, characterized in that the hybrid thin film encapsulation. electrochemical devices; and
A hybrid thin film encapsulation of any one of claims 1 to 6, which is laminated on the electrochemical device.
The hybrid thin film encapsulation comprises an organic material layer containing parylene and an inorganic material layer stacked on the organic material layer, a secondary battery. 8. The method of claim 7 .
The secondary battery is an all-solid-state thin film secondary battery, characterized in that the secondary battery. forming an organic material layer including parylene on the electrochemical device; and
A hybrid thin film encapsulation manufacturing method comprising; forming an inorganic layer on the organic layer. 10. The method of claim 9,
The inorganic material layer forming step,
depositing a silicon nitride (SiNx) layer;
_{Coating a SiO 2} sol (silica sol) on a silicon nitride (SiNx) layer; and
SiO ₂ Heat treatment of the sol to form a silicon oxide (SiOy) layer, and a silicon nitride oxide (SiNxOy) layer between the silicon nitride (SiNx) layer and the silicon oxide (SiOy) layer; characterized in that it comprises a, hybrid A method for manufacturing a thin film encapsulation. 10. The method of claim 9,
The silicon nitride oxide (SiNxOy) layer is a hybrid thin film encapsulation manufacturing method, characterized in that it is formed by solid-state diffusion of SiNx and SiOy at the interface between the silicon nitride (SiNx) layer and the silicon oxide (SiOy) layer. 10. The method of claim 9,
The silicon nitride oxide (SiNxOy) layer is a hybrid thin film encapsulation manufacturing method, characterized in that it is formed by heat treatment at a temperature of 80 to 160 ℃. 10. The method of claim 9,
The silicon nitride oxide (SiNxOy) layer is a hybrid thin film encapsulation manufacturing method, characterized in that it is formed by heat treatment for 5 to 15 hours.

Images