KR20200084209A - Lithium primary battery having inorganic coating layer with excellent thermal stability - Google Patents

Abstract

Disclosed is a lithium primary battery having an inorganic coating layer with excellent thermal stability, which is designated to overcome an initial voltage delay effect occurring in an early stage discharge process. According to the present invention, the lithium primary battery comprises: a case having an open upper side and having an electrolyte immersed thereinto; a lithium negative electrode disposed inside the case; a positive electrode disposed inside the case to face the lithium negative electrode; a separator disposed between the lithium negative electrode and the positive electrode; and a header covering and sealing the upper side of the case. The lithium negative electrode comprises a lithium metal layer and an inorganic coating layer covering a surface of the lithium metal layer.

Description

Lithium primary battery with inorganic coating layer with excellent thermal stability{LITHIUM PRIMARY BATTERY HAVING INORGANIC COATING LAYER WITH EXCELLENT THERMAL STABILITY}

The present invention relates to a lithium primary battery having an inorganic coating layer having excellent thermal stability, and more specifically, a lithium primary battery having an inorganic coating layer having excellent thermal stability, which is designed to overcome an initial voltage delay phenomenon generated during an initial discharge process. It is about.

Generally, a battery is a driving source that generates electricity by inducing an oxidation/reduction reaction of a chemical substance, and is used for supplying electricity to various types and purposes of equipment because it is easy to carry and can be manufactured in a small size.

Lithium thionyl chloride battery (Li/SOCl ₂ ), which is a lithium primary battery, has excellent energy density and high operating voltage characteristics of 3 V or more, and thus is widely used as a power source having high capacity and long-term reliability.

Lithium thionyl chloride batteries with these advantages also have lithium chloride (LiCl), a non-conductive film generated on the surface of lithium, when used for a long time after storage, resulting in increased internal resistance, resulting in a decrease in initial voltage and a decrease in operating voltage. There were problems.

In order to solve this, conventionally, a cathodic treatment technology in which a cyanoacrylate-based organic material is coated on the surface of a lithium anode has been applied.

However, this technique shortened the initial voltage delay time to within a few seconds to hundreds of seconds, but did not improve the phenomenon of a drop in the lowest minimum voltage (TMV) after high temperature storage above 70°C.

In addition, the conventional cyanoacrylate (cyanoacrylate)-based cathodic treatment technology coated with an organic material is a gas generated by a chemical reaction in organic sulfonyl (SO ₂ Cl ₂ ) electrolyte or thionyl (SOCl ₂ ) electrolyte The product accumulates and there is a problem of continuously increasing the internal pressure of the battery.

In addition, the organic coating layer had a problem in that it was vulnerable to safety degradation, ignition, and other safety during thermal shock because a problem of deformation and hardening occurred at a temperature higher than the thermal deformation temperature of the polymer.

As a related prior document, there is Korean Patent Registration No. 10-0873166 (announced on December 10, 2008), and the document describes a lithium/thionyl chloride battery.

An object of the present invention is to provide a lithium primary battery having an inorganic coating layer having excellent thermal stability, which is designed to overcome an initial voltage delay phenomenon generated during an initial discharge process.

Lithium primary battery having an inorganic coating layer excellent in thermal stability according to an embodiment of the present invention for achieving the above object is the upper side is opened, the case is impregnated with an electrolyte solution; A lithium negative electrode disposed inside the case; An anode disposed inside the case to face the lithium anode; A separator disposed between the lithium anode and the anode; And a header covering and sealing the upper side of the case, wherein the lithium negative electrode comprises a lithium metal layer and an inorganic coating layer covering the surface of the lithium metal layer.

The lithium negative electrode, positive electrode, and separator have a winding structure wound in a roll shape inside the case.

The inorganic coating layer has a thickness of 1 ~ 100㎛.

The inorganic coating layer includes 70 to 99% by weight of ceramic particles and 1 to 30% by weight of binder.

At this time, the ceramic particles are Li _{1 + x} Al _x Ge _{2 -x} (PO ₄ ) ₃ (LAGP), Li _{1 + x} Al _x Ti _{2 -x} (PO ₄ ) ₃ (LATP), Li _{1 + x} Ti _{2 - x Al x Si y (PO} 4) 3 -y, LiAl x Zr 2 -x (PO 4) 3, LiTi x Zr 2 -x (PO 4) 3, Li 10 GeP 2 S 12 (LGPS) and Al ₂ O ₃ may include one or more selected from among ceramic materials.

(Where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1)

The ceramic particles preferably have an average particle size of 1 ~ 30㎛.

In addition, the binder includes at least one selected from polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), polyvinyleden floride (PVDF), polyvinyl alcohol (PVA), and epoxy resin.

A lithium primary battery having an inorganic coating layer having excellent thermal stability according to the present invention does not coat a cyanoacrylate-based organic material on the surface of a lithium anode, but forms an inorganic coating layer containing ceramic particles and a binder. Thereby, the generation of internal pressure can be reduced by minimizing the organic matter.

In the technique of coating the existing organic material by heat generated at the end of discharge, there was a possibility of deformation and ignition of the coating layer, but the lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention has a flash point on the surface of the lithium anode. And by forming a ceramic-based inorganic coating layer having a considerably high heat deflection temperature, it is possible to effectively dissipate heat generated from the lithium anode, thereby ensuring excellent thermal stability, as well as fundamentally deforming and igniting potential of the coating layer. Can be solved.

As a result, the lithium primary battery having an inorganic coating layer having excellent thermal stability according to the present invention can effectively improve the initial voltage delay because the ceramic particle strength is higher than the prior art polymer, even in the surface strength directly contributing to the initial voltage delay phenomenon. .

1 is a cross-sectional view showing a lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention.
Figure 2 is a plan view showing a lithium primary battery having an inorganic coating layer excellent in thermal stability according to an embodiment of the present invention.
3 is an enlarged cross-sectional view of the lithium anode of FIG. 1.
Figure 4 is a graph showing the results of evaluating the initial output characteristics of the lithium primary battery prepared according to Example 1 and Comparative Example 1.
5 is a graph showing the results of evaluating the output characteristics of the lithium primary battery prepared according to Example 2 and Comparative Example 2.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Hereinafter, a lithium primary battery having an inorganic coating layer having excellent thermal stability according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention, and FIG. 2 is a plan view showing a lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention to be.

1 and 2, the lithium primary battery 100 having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention is a case 110, a lithium cathode 120, a cathode 130, a separator 140 ) And header 150.

The upper side of the case 110 is opened, and an electrolyte is impregnated therein. The case 110 may have a cylindrical shape in which the upper side is opened, or may be designed in a rectangular shape such as a rectangular parallelepiped or a hexagonal column. Stainless steel (SUS) may be used as the material of the case 110, but is not limited thereto.

At this time, as the electrolyte, sulfonyl (SO ₂ Cl ₂ ) electrolyte or thionyl (SOCl ₂ ) electrolyte may be used, but is not limited thereto.

The lithium negative electrode 120 is disposed inside the case 110 and is wound facing the positive electrode 130. The lithium cathode 120 is electrically separated from the anode 130 by the separator 140. In particular, in the present invention, the lithium negative electrode 120 may have an inorganic coating layer (124 of FIG. 3), and the detailed configuration of the lithium negative electrode 120 will be described later.

The positive electrode 130 is disposed inside the case 110 and is wound around the negative electrode 120. At this time, the positive electrode 130 may be made of a material made of carbon and a binder, but is not limited thereto.

The separator 140 is disposed between the lithium negative electrode 120 and the positive electrode 130. Accordingly, the lithium negative electrode 120, the positive electrode 130, and the separator 140 have a winding structure wound in a roll shape inside the case 110, and are inserted into the case 110 in which the upper side is opened.

The separator 140 is disposed between the lithium negative electrode 120 and the positive electrode 130 to electrically separate the lithium negative electrode 120 from the positive electrode 130. At this time, the material of the separator 140 is glass fiber (Glass Fiber), polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyacrylonitrile ( PAN), polyacrylamide (PAAm), polytetrafluoro ethylene (PTFE), polysulfone, polyethersulfone (PES), polycarbonate (PC), polyamide (PA), polyimide (PI), polyethylene oxide ( PEO), polypropylene oxide (PPO), a microporous film prepared by using at least one polymer selected from the group consisting of cellulose-based polymers and polyacrylic polymers may be used. In addition, the separator 140 may be a multilayer film obtained by polymerizing a porous film.

The header 150 covers and seals the upper side of the case 110. The header 150 may be joined to the case 110 by spot welding or laser welding. At this time, the header 150 may be coupled to the glass 170, the header portion 160 may be fastened to the central portion of the header 150.

In addition, although not shown in detail in the drawings, the header 150 may be provided with an electrolyte injection hole (not shown) for impregnating the electrolyte.

At this time, in the present invention, the lithium anode 120 and the anode 130 and the separator 140 between the lithium anode 120 and the anode 130 are stacked in a parallel structure inside the case 110 in which the upper side is opened. In the roll (ROLL) has a winding structure, the lithium cathode 120, the anode 130 and the separator 140 is inserted into the center of the case (110). Thereafter, after welding the upper side of the case 110 with the header 150, after impregnating the electrolyte inside the case 110 through the electrolyte injection hole of the header 150, a final sub-ball (not shown) It is sealed by welding.

At this time, the upper insulating plate 145 may be further disposed on the lower surface of the header 150. The upper insulating plate 145 prevents the electrolyte from leaking inside the case 110.

Meanwhile, FIG. 3 is an enlarged cross-sectional view of the lithium negative electrode of FIG. 1, and will be described in more detail with reference to this.

3, the lithium cathode 120 according to an embodiment of the present invention includes a lithium metal layer 122 and an inorganic coating layer 124 covering the surface of the lithium metal layer 122.

As described above, in the present invention, by forming the inorganic coating layer 124 on the surface of the lithium metal layer 122, the inorganic coating layer 124 can not only inhibit the growth of LiCl, but also occur in the lithium metal layer 122. It can dissipate heat effectively and contribute to improving stability. As a result, it is possible to improve the electrical output characteristics and thermal stability of the lithium primary battery.

To this end, the inorganic coating layer 124 includes ceramic particles and a binder. More specifically, the inorganic coating layer 124 preferably includes 70 to 99% by weight of ceramic particles and 1 to 30% by weight of binder.

The ceramic particles are Li _{1 + x} Al _x Ge _{2 -x} (PO ₄ ) ₃ (LAGP), Li _{1 + x} Al _x Ti _{2 -x} (PO ₄ ) ₃ (LATP), Li _{1 + x} Ti _{2 -x} Al _x Si _y (PO ₄ ) _3-y , LiAl _x Zr _{2 -x} (PO ₄ ) ₃ , LiTi _x Zr _{2 -x} (PO ₄ ) _3, Li ₁₀ GeP ₂ S ₁₂ (LGPS) and Al ₂ O ₃ It includes at least one selected from among the ceramic materials, and it is preferable to use LATP.

Here, 0≤x≤1 and 0≤y≤1.

In addition, the binder may include one or more selected from polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), polyvinyleden floride (PVDF), polyimide (PI), polyvinyl alcohol (PVA), and epoxy resin. It is preferable to use heavy PVC.

If the addition amount of the ceramic particles is less than 70% by weight, it may be difficult to properly exhibit the heat dissipation effect. Conversely, when the addition amount of the ceramic particles exceeds 99% by weight, the binder content may be low, and thus the coating layer may be detached due to a decrease in binding force.

The inorganic coating layer 124 preferably has a thickness of 1 ~ 100㎛. When the thickness of the inorganic coating layer 124 is less than 1 µm, the thickness is too thin, so the heat dissipation effect is weak, so it may be difficult to properly exhibit the effect of improving the thermal stability, and it may not effectively prevent the growth of LiCl, thereby improving the initial voltage delay. It may not be. Conversely, when the thickness of the inorganic coating layer 124 exceeds 100 μm, it may act as a factor to increase only the thickness without increasing the effect, and is not economical, and the battery output may be reduced due to the increase in internal resistance due to the increase in thickness. Can.

In addition, it is preferable to use ceramic particles having an average particle size of 1 to 30 μm. When the average particle size of the ceramic particles is less than 1 μm, the adhesion force may be reduced due to the problem of dispersibility of the particles as the size becomes finer. Conversely, when the average particle size of the ceramic particles exceeds 30 μm, it is necessary to relatively increase the binder content, so that it may be difficult to properly exhibit the effect of improving the thermal stability.

As described so far, the lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention does not coat the surface of the lithium anode with a cyanoacrylate-based organic material, but also ceramic particles and By forming the inorganic coating layer containing the binder, it is possible to minimize the organic matter and reduce the occurrence of internal pressure.

In the technique of coating the existing organic material by heat generated at the end of discharge, there was a possibility of deformation and ignition of the coating layer, but the lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention has a flash point on the surface of the lithium anode. And by forming a ceramic-based inorganic coating layer having a considerably high heat deflection temperature, it is possible to effectively dissipate heat generated from the lithium anode, thereby ensuring excellent thermal stability, as well as fundamentally deforming and igniting potential of the coating layer. Can be solved.

As a result, the lithium primary battery having an inorganic coating layer having excellent thermal stability according to an embodiment of the present invention has a higher ceramic particle strength than the prior art polymer, even at the surface strength directly contributing to the initial voltage delay phenomenon, thereby effectively improving the initial voltage delay. can do.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is provided as a preferred example of the present invention and cannot be interpreted as limiting the present invention by any means.

The contents not described herein will be sufficiently technically inferred by those skilled in the art, and thus the description thereof will be omitted.

One. Lithium primary battery Produce

Example One

On the surface of the lithium metal layer, an inorganic coating layer composed of 85 wt% of LATP and 15 wt% of polyvinyl chloride (PVC) having an average particle size of 17 μm was formed to a thickness of 25 μm to prepare a lithium negative electrode.

Next, a long separator was placed between the lithium negative electrode and the positive electrode, and wound into a rolled structure to be inserted into a case in which the upper side was opened.

Next, after welding the upper side of the case with a header, a lithium primary battery was manufactured by injecting and sealing the electrolyte inside the case through the electrolyte injection hole of the header.

Example 2

The same method as in Example 1, except that a lithium negative electrode was prepared by forming an inorganic coating layer composed of 76 wt% of LATP and 24 wt% of polyvinyl chloride (PVC) having an average particle size of 11 μm on the surface of the lithium metal layer to a thickness of 100 μm. In order to prepare a lithium primary battery.

Comparative example One

A lithium negative electrode composed of only a lithium metal layer was prepared without forming an inorganic coating layer.

Next, a long separator was placed between the lithium negative electrode and the positive electrode, and wound into a rolled structure to be inserted into a case in which the upper side was opened.

Next, after welding the upper side of the case with a header, a lithium primary battery was manufactured by injecting and sealing the electrolyte inside the case through the electrolyte injection hole of the header.

Comparative example 2

On the surface of the lithium metal layer, an organic material coating layer made of cyanoacrylate was formed to a thickness of 120 µm to prepare a lithium negative electrode.

Next, a long separator was placed between the lithium negative electrode and the positive electrode, and wound into a rolled structure to be inserted into a case in which the upper side was opened.

Next, after welding the upper side of the case with a header, a lithium primary battery was manufactured by injecting and sealing the electrolyte inside the case through the electrolyte injection hole of the header.

2. Property evaluation

Table 1 compares the properties of the coating materials used in Example 1 and Comparative Example 2.

[Table 1]

As shown in Table 1, the organic material cyanoacrylate (cyanoacrylate) has a flash point of approximately 85 to 93°C, but the ceramic type LATP has a flash point of approximately 500°C or higher, which is significantly higher than that of organic materials.

In addition, the organic material cyanoacrylate (cyanoacrylate) has a heat deflection temperature of approximately 74 to 100°C, but the ceramic type LATP has a heat deflection temperature of approximately 900°C or higher.

On the other hand, Figure 4 is a graph showing the results of evaluating the initial output characteristics of the lithium primary battery prepared according to Example 1 and Comparative Example 1. At this time, after accelerating the high temperature under the storage condition of 72°C for 3 days, the initial output of the lithium primary battery prepared according to Example 1 and Comparative Example 1 was measured.

As illustrated in FIG. 4, the initial output characteristics of the lithium primary battery prepared according to Example 1 in which the inorganic coating layer was formed is significantly higher than that of the lithium primary battery prepared according to Comparative Example 1 in which the coating layer is not formed on the lithium anode. You can see the improvement.

5 is a graph showing the results of evaluating the output characteristics of the lithium primary battery prepared according to Example 2 and Comparative Example 2. At this time, after the battery capacity 1% pre-discharge, after accelerating the high temperature in 72 days 3 days storage conditions, the initial output of the lithium primary battery prepared according to Example 2 and Comparative Example 2 was measured.

As shown in FIG. 5, it can be seen that the lithium primary battery prepared according to Example 2 in which the inorganic coating layer was formed was improved compared to the lithium primary battery prepared according to Comparative Example 2 in which the organic coating layer was formed.

As can be seen from the above experimental results, the lithium primary batteries prepared according to Examples 1 to 2 have not only excellent thermal stability due to a very high flash point and heat deflection temperature, as well as lithium primary batteries prepared according to Comparative Examples 1 to 2. Compared with the above, it was confirmed that the electrical output characteristics were improved.

In the above, the embodiments of the present invention have been mainly described, but various changes or modifications can be made at the level of a person skilled in the art to which the present invention pertains. Such changes and modifications can be said to belong to the present invention without departing from the scope of the technical idea provided by the present invention. Therefore, the scope of the present invention should be judged by the claims set forth below.

100: lithium primary battery 110: case
120: lithium cathode 122: lithium metal layer
124: inorganic coating layer 130: anode
140: separator 150: header
160: header pin

Claims (7)

A case in which the upper side is opened and the electrolyte is impregnated therein;
A lithium negative electrode disposed inside the case;
An anode disposed inside the case to face the lithium anode;
A separator disposed between the lithium anode and the anode; And
Includes a header that covers and seals the upper side of the case.
The lithium negative electrode is a lithium primary battery having an inorganic coating layer excellent in thermal stability, characterized in that it comprises a lithium metal layer, an inorganic coating layer covering the surface of the lithium metal layer.
According to claim 1,
The lithium negative electrode, the positive electrode and the separator
Lithium primary battery having an inorganic coating layer having excellent thermal stability, characterized in that it has a winding structure wound in a roll form inside the case.
According to claim 1,
The inorganic coating layer
Lithium primary battery having an inorganic coating layer having excellent thermal stability, characterized in that it has a thickness of 1 ~ 100㎛.
According to claim 1,
The inorganic coating layer
A lithium primary battery having an inorganic coating layer having excellent thermal stability, comprising 70 to 99% by weight of ceramic particles and 1 to 30% by weight of a binder.
According to claim 4,
The ceramic particles
Li _{1 + x} Al _x Ge _{2 -x} (PO ₄ ) ₃ (LAGP), Li _{1 + x} Al _x Ti _{2 -x} (PO ₄ ) ₃ (LATP), Li _{1 + x} Ti _{2 - x} Al _x Si _y Ceramic containing (PO ₄ ) _{3 -y} , LiAl _x Zr _2-x (PO ₄ ) ₃ , LiTi _x Zr _{2 -x} (PO ₄ ) ₃ , Li ₁₀ GeP ₂ S ₁₂ (LGPS) and Al ₂ O ₃ Lithium primary battery having an inorganic coating layer excellent in thermal stability, characterized in that it comprises at least one selected from the material.
(Where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1)
According to claim 4,
The ceramic particles
Lithium primary battery having an inorganic coating layer having excellent thermal stability, characterized in that it has an average particle size of 1 ~ 30㎛.
According to claim 4,
The binder
Excellent thermal stability, characterized by containing at least one selected from polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), polyvinyleden floride (PVDF), polyimide (PI), polyvinyl alcohol (PVA), and epoxy resin. Lithium primary battery having an inorganic coating layer.

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