KR20240156005A - Apparatus of transfer system with external perturbation to form an artificial protective layer on lithium metal anode - Google Patents

Abstract

The present invention relates to an external perturbation transfer equipment system that enables stable interface bonding by injecting various external energies during a rolling transfer process to form an artificial protective layer on the surface of a lithium metal negative electrode for a secondary battery.

Description

{APPARATUS OF TRANSFER SYSTEM WITH EXTERNAL PERTURBATION TO FORM AN ARTIFICIAL PROTECTIVE LAYER ON LITHIUM METAL ANODE}

The present invention relates to an external perturbation transfer equipment system that enables stable interfacial bonding of an artificial protective layer to the surface of a lithium metal negative electrode for a secondary battery.

Currently, commercially available secondary battery cathodes use cathode materials with graphite as the main component. Graphite has the advantage of high stability, but it has the characteristic of storing only one lithium atom per six carbon atoms (Li ⁺ + C ₆ + e ^- ↔ LiC ₆ ), which is the biggest obstacle to improving the energy storage density characteristics of batteries due to its low theoretical specific capacity (Theoretical specific capacity ~ 350 mAh/g).

On the other hand, lithium metal anodes are considered the most ideal anode material for all types of lithium-based secondary battery systems due to their ability to store large amounts of energy due to their low equilibrium potential (-3.04 V vs. SHE), extremely high theoretical specific capacity (~3860 mAh/g), and light density characteristics (0.534 g/cc).

However, the lithium metal anode undergoes plating/stripping reactions during repeated charge-discharge processes and forms a dendrite structure, which causes structural instability of the electrode (cathode). This structural instability can eventually cause various stability problems as follows. 1) Secondary battery fire due to short-circuit of the device, 2) continuous consumption of electrolyte due to side reaction between lithium with a high surface area formed in the dendrite and electrolyte, 3) short battery life characteristics due to generation of inactive lithium (dead lithium), and 4) voltage decrease due to increased polarization are representative device characteristic degrading phenomena. In particular, this instability can be further aggravated under high-power conditions (e.g., fast charging).

Accordingly, the current lithium-metal anode is having difficulties in practical application due to the critical problem that its life characteristics (stability) cannot be secured, and technologies are being developed to improve the stability of lithium-metal anodes to overcome this.

Specifically, technologies for improving the stability of the lithium-metal negative electrode include a three-dimensional nanostructure host technology strategy, an electrolyte additive strategy, and an artificial protective layer strategy.

The first technology, electrode technology using three-dimensional nanostructures, is based on the main mechanism of significantly increasing the actual working surface area of the electrode, thereby minimizing the effective current density when the actual reaction occurs, thereby inducing stable lithium charge/discharge behavior. In addition, it is a technology with the concept that even if lithium is formed in the form of needles by a complex three-dimensional internal porous structure, it is trapped inside the structure to secure structural stability. However, this technological approach has some limitations in practical application due to the insufficient manufacturing cost and productivity of the three-dimensional nanostructure, the weight and large volume of the three-dimensional nanostructure itself, the increased occurrence of lithium metal-electrolyte side reactions due to the large reaction surface area, and the formation and accumulation of excessive solid electrolyte-interfacial materials.

The second technology, electrolyte additive technology, is a chemical concept approach that optimizes the surrounding electrolyte composition atmosphere when lithium ions and electrodes electrochemically react, thereby inducing lithium behavior in a form that is spread out as widely as possible. This technology seems very effective because it can improve stability of the current battery without any additional process with only the cost of the raw materials of the additive, but there is a fundamental problem in that the composition of the electrolyte changes during repeated charging and discharging, the additive is consumed, and its effect gradually decreases. In addition, since the next-generation secondary battery is being developed as an all-solid-state battery using a solid electrolyte, the future usefulness of liquid electrolyte-based additive technology is questionable.

Therefore, the third technology, which is to form an artificial protective layer on the surface of the lithium metal anode, has the most commercialization potential. The artificial protective layer is formed thinly on the surface of the lithium metal anode and can perform various roles. Representative examples include uniform distribution of lithium ion flux, mechanical inhibition of needle-like lithium growth, minimized solid-electrolyte interface (SEI) formation, and control of the solid-state diffusion rate of lithium ions. Through such combined effects and optimization of each effect, lithium behavior with very high stability can ultimately be induced. This approach is expected to be easily applied to next-generation secondary batteries with the development of solid electrolytes and the commercialization of all-solid-state batteries in the future.

Republic of Korea Patent No. 10-2488680 (Announcement Date: 2023.01.17.)

The present invention has been made to solve the above-described problems, and the purpose of the present invention is to provide an external perturbation transfer equipment system that enables stable interface bonding by injecting various external energies during a rolling transfer process for forming an artificial protective layer on the surface of a lithium metal negative electrode for a secondary battery.

In order to achieve the above-described purpose, the external perturbation transfer equipment system according to the present invention is a transfer equipment system for forming an artificial protective layer on the surface of a lithium metal layer, the system including: a transfer unit for unidirectionally transferring a manufacturing object having an artificial protective layer laminated on the surface of the lithium metal layer; a heating unit for heating the transported manufacturing object to a predetermined temperature by injecting external energy therein to induce fusion between the lithium metal layer and the artificial protective layer; a first rolling roller unit for first rolling the manufacturing object that has passed through the heating unit by passing it between at least one pair of rotating rollers; and a second rolling roller unit formed with a larger diameter than the first rolling roller unit and for secondarily rolling the manufacturing object that has passed through the first rolling roller unit at a higher pressure than the first rolling roller unit.

In this case, the heating unit may include a laser module comprising a laser source that emits light energy, and a scanner that receives the emitted light energy through an aperture, a plurality of reflectors, and an attenuator and adjusts the focusing position of the light.

In addition, the heating unit may further include a lamp that emits light energy, and a lamp module that irradiates light in the width direction of the manufacturing target object through a reflector and a light collecting plate with the emitted light energy.

In addition, the heating unit may further include a high-frequency induction heater in which a high-frequency induction heating coil is wound and installed on the outer surface of the manufacturing target.

In addition, at least one of the upper and lower rollers of the first rolling roller section may further include an ultrasonic vibration generator that applies ultrasonic vibration to a manufacturing target passing through the first rolling roller section.

The external perturbation transfer equipment system for transferring an artificial protective layer surface of a lithium metal negative electrode according to the present invention having the above configuration can, during a rolling transfer process of a manufacturing target to form an artificial protective layer on the surface of a lithium metal layer, heat the manufacturing target to a predetermined temperature by injecting various external energies including optical energy and electrical energy immediately before rolling the manufacturing target without performing rolling only through mechanical pressure, thereby softening the lithium metal layer and inducing efficient fusion of the interface with the artificial protective layer to be transferred.

In addition, since the rolling process temperature can be controlled more precisely, the residual stress on the electrode after rolling can be relieved, and accordingly, the bending or warpage of the electrode can be compensated for, thereby producing a high-quality electrode with high dimensional precision.

In addition, the material inside the electrode is composed of active material powder, conductive nanoparticles, and a polymer binder. The process of melting and bonding the polymer through high-temperature rolling creates a process that makes the adhesion of the polymer between the powders more dense after rolling, thereby manufacturing a mechanically stable electrode.

Figure 1 is a cross-sectional side view showing the laminated structure of a negative electrode for a secondary battery according to the present invention.
Figure 2 is a schematic perspective view showing the overall configuration of a transcription equipment system according to the present invention;
Figure 3 is a side view of Figure 2.

The configuration and operation of specific embodiments of the present invention will be described in detail with reference to the attached drawings.

Here, when adding reference signs to components of each drawing, it should be noted that identical components are indicated with the same signs as much as possible, even if they are shown in different drawings.

FIG. 1 is a cross-sectional side view showing the laminated structure of a negative electrode for a secondary battery according to the present invention, and FIG. 2 is a schematic perspective view showing the entire configuration of a transfer equipment system according to the present invention.

Referring to FIGS. 1 and 2, the present invention is for rolling and transferring an artificial protective layer (13) to the surface of a lithium metal layer (11) constituting an anode of a secondary battery. According to a preferred embodiment, an external perturbation transfer equipment system (1) for transferring an artificial protective layer surface of a lithium-metal anode may include a conveying unit (100), a heating unit (200), a first rolling roller unit (300), and a second rolling roller unit (400).

The composition of the present invention is specifically described as follows.

First, the above-mentioned transport unit (100) transports in one direction a manufacturing target (negative electrode) (10) in which an artificial protective layer (13) is laminated on the surface of a lithium metal layer (11). A structure that can transport the manufacturing target (10) using a plurality of rollers or conveyors can be selectively applied to this transport unit (100). The present invention does not specifically limit the configuration of the transport unit (100).

The heating unit (200) above is configured to heat the manufacturing object (10) to a predetermined temperature by injecting various external energies into the manufacturing object (10) immediately before performing the rolling transfer process of the manufacturing object (10) being transported. The heating unit (200) can soften the lithium metal layer (11) by heating the manufacturing object (10) and induce efficient fusion of the interface with the artificial protective layer (13) to be transferred.

Specifically, a method for injecting external energy into the manufacturing target (10) through the heating unit (200) can utilize optical energy such as a laser module (210) and a lamp module (220).

First, the laser module (210) may include a laser source (211) that emits light energy, and a scanner (213) that receives the emitted light energy through an aperture, multiple reflectors, and an attenuator, and finally adjusts the focusing position of the light. The laser module (210) can accurately irradiate a laser beam between the upper and lower rollers that constitute the first rolling roller unit (300) to be described later. In addition, the laser module (210) can scan a laser beam in the width direction of the manufacturing target (10) during operation, thereby inducing the fusion of the lithium metal layer (11) and the artificial protective layer (13) immediately before the rolling process of the manufacturing target (10).

The above lamp module (220) may include a lamp (221) that emits light energy, and a reflector (223) and a light collecting plate that emits the emitted light energy, and may irradiate light in a width direction intersecting with the direction in which the manufacturing target (10) is transported through the lamp module (220). In this case, the light of the lamp module (220) may be irradiated on the manufacturing target (10) at a stage prior to the rolling process to increase the temperature to a certain level, thereby preventing the manufacturing target (10) from being damaged due to a rapid temperature increase caused by the laser of the laser module (210).

In addition, the heating unit (200) may additionally utilize electrical energy such as a high-frequency induction heater (230) when a high-temperature material fusion process is required. The high-frequency induction heater (230) may perform high-frequency induction heating on the manufacturing target (10) by winding a high-frequency induction heating coil (231) on the outer surface of the manufacturing target (10) before the rolling transfer process. In this case, it is preferable that the high-frequency induction heater (230) be located behind the optical energy laser module (210) and lamp module (220) in the transport direction of the manufacturing target (10).

The first rolling roller unit (300) can first roll a manufacturing target (10) that has passed through a heating unit (200) by passing it between at least one pair of rotating rollers (310)(320). The first rolling roller unit (300) can use rollers (310)(320) with a smaller diameter than the second rolling roller unit (400) described below, and can perform a first rolling transfer process of the manufacturing target (10) by low-pressure mechanical pressing together with precisely controlled heating through the heating unit (200).

In this case, at least one of the upper roller (310) and the lower roller (320) of the first rolling roller unit (300) may be equipped with an ultrasonic vibration generator (330) that applies ultrasonic vibration to the manufacturing target (10) passing through the first rolling roller unit (300).

Specifically, the ultrasonic vibration generator (330) can be symmetrically installed on the rotation shaft (321) on both sides of the lower roller (320). Through the ultrasonic vibration generator (330), the surface of the lithium metal layer (11) melts due to frictional heat and impact force generated by rapid vibration at the interface between the lithium metal layer (11) and the artificial protective layer (13) being rolled and transferred, and the artificial protective layer (13) material can be strongly embedded. Accordingly, high-speed, high-efficiency transfer is possible.

At this time, the lower roller (320) of the first rolling roller unit (300) is formed with a smaller diameter than the second rolling roller unit (400) described later, so that the vibration motion transmitted from the ultrasonic vibration generator (330) can be well transmitted to the surface of the manufacturing target (10) being rolled.

In this case, the vibration of the ultrasonic vibration generator (330) occurs in a random direction, and in order to control the directionality of the vibration, a structure (331) having very high rigidity in the horizontal direction (x, y) and low rigidity in the vertical direction (z) can be installed together with the ultrasonic vibration generator (330). Accordingly, the vibration of the ultrasonic vibration generator (330) can be controlled to occur in the vertical direction in which the lower roller (320) is provided.

Referring to FIG. 3, the second rolling roller unit (400) performs a second rolling of the manufacturing target (10) that has passed through the first rolling roller unit (300). The rollers (410) (420) of the second rolling roller unit (400) are formed with a larger diameter than the first rolling roller unit (300), so that the product can be finished while performing the second rolling of the manufacturing target (10) at a higher pressure than the first rolling.

In this case, in the second finishing rolling through the second rolling roller section (400), defects, voids, etc. of the material that may occur in the first rolling transfer process can be pressed and removed, and the transferred manufacturing target (10) can have a uniform thickness and properties in the width direction of the roll.

In addition, even after the secondary rolling, additional elements such as a 3rd process (heating-cooling, rolling) may be added to resolve crystal phase changes and residual stress of the material of the manufacturing target (10) if necessary.

In addition, the rollers applied to the first and second rolling roller units (300)(400) are not limited to a simple two-stage rolling mill form, and may be configured in the form of a four-stage rolling mill with support rollers attached to the upper and lower sides, a six-stage rolling mill, or a sensor rolling mill.

Also, the roller can mean a precision-machined roller with a concentricity of 2㎛ or less made of aluminum or stainless steel, and a special coating can be applied to the surface of the roller depending on the purpose of the roller and process optimization. For example, the surface of the roller can be coated with metal materials such as titanium, chrome, and tungsten, and very soft silicone rubber or styrene-butadiene rubber can be coated to homogenize the contact pressure. In addition, a coating of a Teflon-based material is also possible to minimize contact friction.

The external perturbation transfer equipment system (1) for transferring an artificial protective layer surface of a lithium metal negative electrode according to the present invention having the above configuration can heat the manufacturing object (10) to a predetermined temperature by injecting various external energies including optical energy and electrical energy immediately before rolling during the rolling transfer process of a manufacturing object (10) to form an artificial protective layer (13) on the surface of a lithium metal layer (11), thereby softening the lithium metal layer (11) and inducing efficient fusion of the interface with the artificial protective layer (13) to be transferred.

Although the present invention has been described and illustrated with specific embodiments above, the present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the technical spirit of the present invention.

1: External perturbation transfer equipment system 10: Manufacturing target
11: Lithium metal layer 13: Artificial protective layer
100: transfer section 200: heating section
210 : Laser module 211 : Laser source
213 : Scanner 220 : Lamp module
221 : Lamp 223 : Reflector
230: High frequency induction heater 231: Coil
300: 1st rolling roller section 310: Upper roller
320: Lower roller 321: Rotating shaft
330: Ultrasonic vibration generator 331: Structure
400: Second rolling roller section 410: Upper roller
420 : Lower roller

Claims (5)

In a transfer equipment system for forming an artificial protective layer on the surface of a lithium metal layer,
A transport unit that transports a manufacturing target having an artificial protective layer laminated on the surface of the lithium metal layer in one direction;
A heating unit that heats the above-mentioned transported manufacturing object to a predetermined temperature by injecting external energy to induce fusion between the lithium metal layer and the artificial protective layer;
A first rolling roller section for first rolling the manufacturing target material that has passed through the above heating section by passing it between at least one pair of rotating rollers; and
An external perturbation transfer equipment system, comprising: a second rolling roller section formed with a larger diameter than the first rolling roller section and performing secondary rolling on a manufacturing target that has passed through the first rolling roller section at a higher pressure than the first rolling roller section.
In the first paragraph,
The above heating part,
An external perturbation transfer equipment system comprising a laser module comprising a laser source that emits optical energy, and a scanner that receives the emitted optical energy through an aperture, multiple reflectors, and an attenuator and adjusts the focusing position of the light.
In the second paragraph,
The above heating part,
An external perturbation transfer equipment system further comprising: a lamp that emits light energy; and a lamp module that irradiates light in the width direction of a manufacturing target object through a reflector and a light collector, the irradiated light energy being transferred thereto.
In the first paragraph,
The above heating part,
An external perturbation transfer equipment system further comprising a high-frequency induction heater having a high-frequency induction heating coil wound and installed on the outer surface of the manufacturing target.
In the first paragraph,
At least one of the upper and lower rollers of the first rolling roller section is provided with:
An external perturbation transfer equipment system further comprising an ultrasonic vibration generator that applies ultrasonic vibration to a manufacturing object passing through the first rolling roller section.

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