KR102649420B1 - Anode, manufacturing method thereof and secondary battery comprising same - Google Patents

Abstract

The cathode according to an embodiment of the present invention includes rolled copper foil and porous silicon embedded in the rolled copper foil.
In this way, the negative electrode, the manufacturing method thereof, and the secondary battery including the same according to the present invention embed porous silicon with high energy density as a negative electrode active material in rolled copper foil, thereby suppressing expansion of the porous silicon during charging and discharging, thereby achieving high battery capacity. While implementing this, safety can also be greatly improved.

Description

Anode, manufacturing method thereof and secondary battery comprising same}

The present invention relates to a negative electrode that has high battery capacity and can also improve safety, a method of manufacturing the same, and a secondary battery including the same.

Secondary batteries, which are mainly used as a power source in mobile devices and small home appliances such as mobile phones, laptops, and cordless vacuum cleaners, are batteries that can convert external electrical energy into chemical energy, store it, and reuse it.

Additionally, recently, in addition to the mobile devices and small home appliances mentioned above, secondary batteries have been used as a main power source in the field of electric vehicles. Types of these secondary batteries include nickel cadmium batteries (NiCd), nickel hydride batteries (NiMH), and lithium ion batteries (Li-ion). Among them, lithium ion batteries are 4 to 5 times more powerful than conventional batteries. It is most widely used due to its energy density, three times higher voltage than existing batteries, non-memory effect, and high lifespan. These lithium-ion batteries are currently being researched into technologies to further increase battery capacity, but in the process, a problem has arisen in which the risk of battery explosion also increases.

Korean Patent Publication No. 10-1999616 (2019.07.08.)

Therefore, the present invention is intended to solve this problem, and the problem to be solved by the present invention is to provide a negative electrode that can further improve safety while having high battery capacity, a method of manufacturing the same, and a secondary battery including the same.

The cathode according to an embodiment of the present invention includes rolled copper foil and porous silicon embedded in the rolled copper foil.

The porous silicon may include silicon carbide in the form of particles, a carbon layer surrounding the surface of the silicon carbide, and a conductive polymer layer surrounding the surface of the carbon layer.

The cathode according to an embodiment of the present invention may further include a protective layer formed on the upper surface of the rolled copper foil with the porous silicon embedded therein.

The protective layer may be made of at least one of carbon, graphene, and PVDF (polyvinylidene fluoride).

A secondary battery according to another embodiment of the present invention includes a negative electrode, a positive electrode containing a positive electrode active material, an electrolyte used as an ion transfer medium between the negative electrode and the positive electrode, and a separator that transfers ions between the negative electrode and the positive electrode. .

A method of manufacturing a cathode according to another embodiment of the present invention includes preparing a rolled copper foil by rolling a bulk type copper foil through a first rolling roller, placing the rolled copper foil on an upper part of a positively charged electrode plate, Steps of charging the rolled copper foil with a positive charge, charging the porous silicon powder with a negative charge, spraying the porous silicon powder negatively charged on the positively charged upper surface of the rolled copper foil to transform a portion of the upper surface of the rolled copper foil into porous silicon. It includes the steps of applying, heat treating the upper surface of the rolled copper foil, and rolling the rolled copper foil with a second rolling roller to bury the porous silicon into the rolled copper foil to manufacture a cathode.

A method of manufacturing a cathode according to another embodiment of the present invention may further include forming a protective layer on the upper surface of the rolled copper foil in which the porous silicon is embedded.

The step of forming a protective layer on the upper surface of the rolled copper foil with the porous silicon embedded therein includes forming the protective layer by applying at least one of carbon, graphene, and PVDF (polyvinylidene fluoride) to the entire upper surface of the rolled copper foil. You can.

In this way, the negative electrode according to the present invention, the method for manufacturing the same, and the secondary battery including the same are embedded in the rolled copper foil with porous silicon having a high energy density as the negative electrode active material, thereby suppressing expansion of the porous silicon during charging and discharging, thereby achieving high battery capacity. While implementing this, safety can also be greatly improved.

1 is a cross-sectional view of a cathode according to an embodiment of the present invention.
Figure 2 is a cross-sectional view of porous silicon.
Figure 3 is a flowchart of a method for manufacturing a cathode according to another embodiment of the present invention.
Figure 4 is a cross-sectional view of the cathode at each stage.
Figure 5 is a diagram showing the direction in which porous silicon embedded in rolled copper foil expands.

Hereinafter, with reference to the attached drawings, preferred embodiments through which the present invention can be easily implemented by those skilled in the art will be described in detail. However, these examples are for illustrating the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

The configuration of the invention to clarify the solution to the problem to be solved by the present invention will be described in detail with reference to the accompanying drawings based on preferred embodiments of the present invention, and the reference numbers to the components in the drawings will be the same. Components are given the same reference numbers even if they are in different drawings, and it is stated in advance that components of other drawings can be cited when necessary when explaining the relevant drawings. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In addition, when explaining in detail the operating principle of a preferred embodiment of the present invention, if it is judged that a detailed description of a known function or configuration related to the present invention and other matters may unnecessarily obscure the gist of the present invention, The detailed description is omitted.

In addition, throughout the specification, when a part is said to be 'connected' to another part, this does not only mean 'directly connected', but also 'indirectly connected' with another element in between. Includes. In addition, 'including' a certain component does not mean excluding other components unless specifically stated to the contrary, but rather means that other components may be further included.

Additionally, terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms may be used for the purpose of distinguishing one component from another component. For example, a first component may be referred to as a second component, and similarly, the second component may be referred to as a first component without departing from the scope of the present invention.

The terms used in the present invention are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of implemented features, numbers, steps, operations, components, parts, or combinations thereof, but are not intended to indicate the presence of one or more other features or numbers. It should be understood that this does not preclude the existence or addition of steps, operations, components, parts, or combinations thereof.

Unless specifically defined differently, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted as having an ideal or excessively formal meaning. .

The present invention relates to a negative electrode that has high battery capacity and can also improve safety, a method of manufacturing the same, and a secondary battery including the same.

Hereinafter, with reference to FIG. 1, we will look at the cathode according to an embodiment of the present invention in more detail.

1 is a cross-sectional view of a cathode according to an embodiment of the present invention.

As shown in FIG. 1, the cathode 100 according to an embodiment of the present invention includes rolled copper foil 120 and porous silicon 140.

The rolled copper foil 120 is prepared to a thin thickness by using a first rolling roller to roll bulk-type copper foil. This rolled copper foil 120 is used as a current collector, and has very excellent copper density compared to electrolytic copper foil produced by plating a base member.

Porous silicon 140 is a negative electrode active material and is embedded inside the rolled copper foil 120. At this time, the porous silicon 140 may be embedded in a position of 50% to 90% of the total thickness of the rolled copper foil 120.

Hereinafter, the porous silicon 140 will be looked at in more detail with reference to FIG. 2.

This porous silicon 140 includes silicon carbide 142, a carbon layer 144, and a conductive polymer layer 146.

Silicon carbide (142, SiC, Silicon carbide) is in the form of particles with a diameter of about 2 um to 8 um, and has a Mohs hardness of 13. At this time, in addition to the silicon carbide 142, silicon oxide (SiOx) can be used, and if it is a silicon-based material with a Mohs hardness higher than the rolled copper foil 120 with a Mohs hardness of 3, the silicon carbide 142 can be replaced. It can be used.

A carbon layer 144 is coated to surround the surface of the silicon carbide 142.

The conductive polymer layer 146 is formed to surround the surface of the carbon layer 144. At this time, the total coating thickness including the carbon layer 144 and the conductive polymer layer 146 is 100 nm to 2 um.

As described above, the anode 100 manufactured according to an embodiment of the present invention can be applied to a secondary battery. In particular, mainly used lithium-ion secondary batteries are formed in a structure in which a polymer separator is added to an electrolyte composed of an organic solvent and lithium salt. During discharging, lithium ions move from the cathode to the anode, and as the lithium is ionized, the generated electrons also move from the cathode to the anode, and during charging, they move in the opposite direction. The driving force for this lithium ion movement is generated by chemical stability depending on the potential difference between the cathode and anode. In particular, capacity (Ah), which indicates the performance of a secondary battery, is determined by the amount of lithium ions moving from the negative electrode to the positive electrode or from the positive electrode to the negative electrode.

Therefore, when applying the negative electrode 100 produced according to an embodiment of the present invention to a secondary battery, the porous silicon 140 used as the negative electrode active material has a relatively large particle size of 2 um to 8 um. By having a high electron tolerance, the battery capacity can be greatly increased by this high electron tolerance.

In addition, as porous silicon 140 with high energy density is embedded inside the rolled copper foil 120, even if the porous silicon 140 tries to expand during the charging and discharging process of the secondary battery, the rolled copper foil 120 By suppressing the expansion of the porous silicon 140, the risk of the secondary battery exploding due to this can be prevented.

Additionally, the cathode 100 according to an embodiment of the present invention may further include a protective layer 160 in addition to the rolled copper foil 120 and the porous silicon 140.

The protective layer 160 is formed on the upper surface of the rolled copper foil 120 with the porous silicon 140 embedded therein. This protective layer 160 may be made of at least one of carbon, graphene, and PVDF (polyvinylidene fluoride). This protective layer 160 not only prevents the porous silicon 140 embedded inside the rolled copper foil 120 from easily leaving the rolled copper foil 120, but also provides conductivity for the porous silicon 140. can be further increased.

Hereinafter, a method for manufacturing a cathode according to another embodiment of the present invention will be examined in detail with reference to FIG. 3.

Figure 3 is a flowchart of a method for manufacturing a cathode according to another embodiment of the present invention.

As shown in Figure 3, in the method of manufacturing a cathode according to another embodiment of the present invention, first, a first rolling roller rolls a bulk type copper foil to prepare a rolled copper foil 120 having a thin thickness. (S210). This rolled copper foil 120 is provided inside the roll-to-roll device, and subsequent steps are performed while moving from the first winding roller to the second winding roller.

At this time, a positively charged electrode plate is positioned between the first winding roller and the second winding roller, and the rolled copper foil 120 is positioned on top of the electrode plate, so that the rolled copper foil 120 is positively charged. (S220).

Additionally, the porous silicon powder 140 is negatively charged (S230).

Thereafter, the injection unit located at the rear end of the electrode plate sprays the porous silicon powder 140, which was negatively charged in the previous step S230, onto the upper surface of the rolled copper foil 120, which was charged positively in step S220, to the rolled copper foil ( A portion of the upper surface of 120) is coated with porous silicon 140 (S240). At this time, the rolled copper foil 120 is charged with a positive charge, and the porous silicon powder 140 is charged with a negative charge, so when the porous silicon powder 140 is sprayed on the upper surface of the rolled copper foil 120, the rolled copper foil 140 is charged with a positive charge. The porous silicon powder 140 may be well attached to the upper surface of 120.

In particular, as shown in FIG. 4(a), the porous silicon 140 is applied to a portion of the rolled copper foil 120 rather than the entire upper surface. At this time, the area to which the porous silicon 140 is applied may be 10% to 80% of the total area of the rolled copper foil 120.

Afterwards, the rolled copper foil 120 moves again for a predetermined section in the direction of the second winding roller through the roll-to-roll device, and then the upper surface of the rolled copper foil 120 is heat treated (S250). At this time, a heat gun is disposed at the rear end of the injection unit, and heat of about 160° C. to 180° C. can be supplied to the upper surface of the rolled copper foil 120.

Subsequently, the rolled copper foil 120 moves again for a predetermined section in the direction of the second winding roller.

At this time, the second rolling roller located at the rear end of the hot air blower rolls the rolled copper foil 120 and embeds the porous silicon 140 located on the upper surface into the rolled copper foil 120 to manufacture the cathode 100. Do it (S260). FIG. 4(b) shows a cross section of the cathode 100 in which the porous silicon 140 is partially exposed to the surface of the rolled copper foil 120 after performing step S260.

That is, when the second rolling roller rolls the rolled copper foil 120 coated with porous silicon 140, a lateral force acts and the rolled copper foil 120 becomes soft, so that the rolled copper foil 120 Porous silicon 140 can be easily embedded therein. In particular, the second rolling roller can perform heat treatment on the rolled copper foil 120 using a steel roll located at the lower part of the rolled copper foil 120 among rollers facing each other with the rolled copper foil 120 in between. there is. At this time, the steel roll may apply heat of 600°C to 800°C to the rolled copper foil 120.

Additionally, the position where the porous silicon 140 is embedded within the rolled copper foil 120 may be 50% to 90% of the total thickness of the rolled copper foil 120. That is, the porous silicon 140 may be embedded between a position that is half of the total thickness of the rolled copper foil 120 and a position close to the surface of the rolled copper foil 120.

In addition, the method of manufacturing a cathode according to another embodiment of the present invention includes, in addition to the above-described steps, the rolled copper foil 120 with the porous silicon 140 embedded therein, as shown in FIG. 4(c). A step of forming a protective layer 160 on the upper surface may be further included. This protective layer 160 may be made of at least one of carbon, graphene, and PVDF (polyvinylidene fluoride). The protective layer 160 absorbs energy from the porous silicon 140 to expand in the vertical direction when charging and discharging the secondary battery using the previously manufactured negative electrode 100 and prevents the porous silicon 140 from expanding in the vertical direction. It can suppress and improve conductivity.

Hereinafter, with reference to FIG. 5, the anode 100 manufactured through the above-described steps is applied to a secondary battery, and when the secondary battery is charged and discharged, the porous silicon 140 embedded in the rolled copper foil 120 expands. Let’s take a closer look at the process of suppressing what you want to do.

Figure 5 is a diagram showing the direction in which porous silicon embedded in rolled copper foil expands.

As shown in FIG. 5, porous silicon 140, which is a negative electrode active material, is embedded inside the rolled copper foil 120, which is a current collector plate within the negative electrode 100. In this state, when the anode 100 is applied to a secondary battery and charges and discharges are performed, the porous silicon 140 tends to expand in the X, Y, and Z directions, respectively, due to the high energy density. At this time, the indicates the direction in which it wants to expand.

However, at this time, the rolled copper foil 120 absorbs energy from the porous silicon 140 to expand in the X and Y directions, respectively. Additionally, when the protective layer 160 is formed in the cathode 100 according to the present invention, the protective layer 160 absorbs energy from the porous silicon 140 to expand in the Z direction.

Therefore, even if the porous silicon 140 tries to expand in the By absorbing the material, the porous silicon 140 is prevented from substantially expanding, thereby preventing explosion of the secondary battery and ensuring the safety of the product.

In this way, the negative electrode according to the present invention, the method for manufacturing the same, and the secondary battery including the same are embedded in the rolled copper foil with porous silicon having a high energy density as the negative electrode active material, thereby suppressing expansion of the porous silicon during charging and discharging, thereby achieving high battery capacity. While implementing this, safety can also be greatly improved.

The preferred embodiments of the present invention described above have been disclosed for illustrative purposes, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions will be possible. The addition should be viewed as falling within the scope of the patent claims below.

100: cathode 120: rolled copper foil
140: porous silicon 142: silicon carbide
144: carbon layer 146: conductive polymer layer
160: protective layer

Claims (8)

Rolled copper foil: and
Porous silicon embedded within 50% to 90% of the total thickness of the rolled copper foil;
A cathode containing.
According to paragraph 1,
The porous silicon is
Silicon carbide in particle form;
a carbon layer surrounding the surface of the silicon carbide; and
A conductive polymer layer surrounding the surface of the carbon layer;
A cathode comprising:
According to paragraph 1,
a protective layer formed on the upper surface of the rolled copper foil with the porous silicon embedded therein;
A cathode characterized in that it further comprises.
According to paragraph 3,
The protective layer is
A cathode characterized by being made of at least one of carbon, graphene, and PVDF (polyvinylidene fluoride).
A cathode according to any one of claims 1 to 4;
A positive electrode containing a positive electrode active material;
An electrolyte used as an ion transfer medium between the cathode and the anode; and
a separator that transfers ions between the cathode and the anode;
A secondary battery containing a.
Preparing rolled copper foil by rolling bulk-type copper foil through a first rolling roller;
Charging the rolled copper foil with a positive charge by placing the rolled copper foil on top of a positively charged electrode plate;
Charging the porous silicon powder with a negative charge;
Spraying the negatively charged porous silicon powder on the positively charged upper surface of the rolled copper foil to coat a portion of the upper surface of the rolled copper foil with porous silicon;
heat treating the upper surface of the rolled copper foil; and
manufacturing a negative electrode by rolling the rolled copper foil with a second rolling roller and embedding the porous silicon at a position of 50% to 90% of the total thickness of the rolled copper foil;
A method of manufacturing a cathode comprising.
According to clause 6,
forming a protective layer on the upper surface of the rolled copper foil with the porous silicon embedded therein;
A method of manufacturing a negative electrode further comprising:
In clause 7,
The step of forming a protective layer on the upper surface of the rolled copper foil with the porous silicon embedded therein is
A method of manufacturing a cathode, characterized in that the protective layer is formed by applying at least one of carbon, graphene, and PVDF (polyvinylidene fluoride) to the entire upper surface of the rolled copper foil.

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