KR102314017B1 - Anode, secondary battery including the same, and manufacturing method thereof - Google Patents

Abstract

The negative electrode according to an embodiment of the present invention includes a porous metal layer comprising a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal, wherein the porous metal layer is in the form of a rod of metal microparticles have a porous three-dimensional network structure that is interconnected.

Description

Anode, secondary battery including same, and manufacturing method thereof

The present invention relates to an anode comprising a porous metal layer having a porous three-dimensional network structure in which micro active material particles including a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal are interconnected. , a method for manufacturing the same, and a secondary battery including the same.

As various portable electronic devices, electric vehicles, etc. are researched and developed, the need for energy storage technology is further increasing. Accordingly, lithium secondary batteries having high energy density and voltage are widely used.

However, due to the high price and limited reserves of lithium, active research is being conducted on a sodium ion battery using sodium having a relatively low price and high energy density as a next-generation battery.

However, even if the graphite negative electrode used in the lithium ion battery is applied to the sodium ion battery, there is a problem that not only cannot achieve a high capacity as in the conventional lithium ion battery, but also a battery having a high energy cannot be developed.

Accordingly, there is a need to develop a new anode capable of achieving a high capacity even when applied to a sodium ion battery.

The present invention has been devised to solve the above problems, and a high-capacity negative electrode comprising a porous metal layer capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal, a method for manufacturing the same and An object of the present invention is to provide a secondary battery including the same.

The negative electrode according to an embodiment of the present invention includes a porous metal layer including a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal.

The porous metal layer may have a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The porous metal layer may have an average pore diameter of 0.1 to 200 μm.

The porous metal layer may have a porosity of 50 to 90% by volume.

The metal microparticles may have an average diameter of 0.1 to 5 μm.

The metal microparticles may have an average length of 0.5 to 20 μm.

The metal microparticles may have an average aspect ratio (length/diameter) of 1 to 10.

The porous metal layer may include 90 wt% or more of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100 wt% of the total porous metal layer.

The porous metal layer may include 90% by weight or more of the metal represented by the following Chemical Formula 1 based on 100% by weight of the total porous metal layer.

[Formula 1]

A _x B

A is Li, Na, Mg, K, or Ca, wherein B is selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi, wherein x is 0 to 6 have.

More specifically, the porous metal layer may include 90% by weight or more of the metal represented by the following Chemical Formula 2 or Chemical Formula 3 based on 100% by weight of the total porous metal layer.

[Formula 2]

Na _y Sn

[Formula 3]

Na _z Bi

The y may be 0 to 1, and the z may be 0 to 3.

A method of manufacturing a secondary battery according to an embodiment of the present invention comprises the steps of constructing a half-cell including a negative electrode including a metal layer and a metal electrode, the half-cell comprising: By performing charging and discharging two or more times, converting the metal layer into a porous metal layer, and a negative electrode including the porous metal layer, a positive electrode including a positive electrode active material, and a full-cell including an electrolyte manufacturing step.

The metal layer may include a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal.

The metal electrode may include an alkali metal or an alkaline earth metal.

The step of converting the metal layer into the porous metal layer may be to perform a cycle of full charge and full discharge by electrically connecting the cathode and the metal electrode.

In the step of converting the metal layer into the porous metal layer, the metal layer may be converted into a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The method may further include manufacturing a cathode including a metal layer by rolling a metal foil before the step of forming the half-cell.

The manufacturing of the negative electrode may be to form a metal layer to a thickness of 25 μm to 2 mm. Specifically, it may be 27 μm to 2 mm.

A secondary battery according to an embodiment of the present invention may include a positive electrode, an electrolyte, and a negative electrode according to an embodiment of the present invention.

The electrolyte may include a metal salt and an ether-based solvent.

The ether solvent is dimethoxyethane (DME), 1,3-dioxolane (1,3-dioxolane), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (Diethylene glycol) dimethyl ether, DEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME), polyethylene oxide (PEO), and mixtures thereof. it could be

A separator may be further included between the anode and the cathode.

The separation membrane may be a nano-pore separation membrane having pores of 10 nm to 100 nm. Specifically, it may be 20 nm to 100 nm, 50 nm to 100 nm, or 80 nm to 100 nm.

The separation membrane may be a micropore separation membrane having pores of 1 μm to 50 μm. Specifically, it may be 3 μm to 50 μm, 5 μm to 50 μm, 10 μm to 50 μm, or 15 μm to 50 μm.

The thickness of the nanopore separator may be 5 μm to 1 mm. Specifically, it may be 10 μm to 1 mm, 15 μm to 1 mm, 20 μm to 1 mm, or 25 μm to 1 mm.

The micropore separation membrane may have pores of 1 μm to 50 μm. Specifically, it may be 3 μm to 50 μm, 5 μm to 50 μm, 8 μm to 50 μm, or 10 μm to 50 μm.

The micropore separator may have a thickness of 0.2 mm to 2 mm. Specifically, it may be 0.5 mm to 2 mm, 0.8 mm to 2 mm, or 1 mm to 2 mm.

The separator may be a multiple separator including a nano-pore separator and a micro-pore separator.

A negative electrode according to an embodiment of the present invention, and a secondary battery including the same, are porous three-dimensional (3D) interconnected metal microparticles capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal. By including the porous metal layer having a network structure, cracking or pulverization does not occur due to volume change of the active material during charging and discharging, cycle characteristics can be improved, and high capacity and high energy can be obtained.

In addition, since the method for manufacturing the negative electrode of the present invention does not include a conventional active material nano-processing in manufacturing the active material layer composed of fine particles, it is possible to facilitate the manufacturing process and reduce the manufacturing cost.

1 is a diagram showing metal micro-particles in the form of rods.
2 is a view showing the structure of the anode porous metal layer according to an embodiment of the present invention.
3 is an actual photograph of the negative electrode porous metal layer of Example 1;
4 is a SEM photograph of the Sn porous metal layer of Example 1;
5 shows the EDS spectrum of the negative electrode porous metal layer of Example 1.
6 is a SEM photograph of Example 1 of a state in which the Sn porous metal layer of the negative electrode completely reacted with Na electrochemically.
7 shows the EDS spectrum results of Example 1 in a state in which the negative electrode porous metal layer was discharged with sodium to 1 mV (Na _{3.75 Sn).}
8 is a charge/discharge graph of the negative electrode of Example 1.
9 is a SEM photograph of the active material layer of the negative electrode of Comparative Example 1.
10 is a charge-discharge graph at 0.1 C-rate of Comparative Example 1.
11 is a cycle graph of the negative electrode of Example 1 and the negative electrode of Comparative Example 1;
12 is an actual photograph of the negative electrode of Example 2;
13 is a SEM photograph of the Bi-porous metal layer of Example 2;
14 is an XRD pattern of Example 2 anode Bi porous metal layer.
15 is a charge/discharge graph of the negative electrode of Example 2.
16 is a graph of 1 to 100 cycles of the negative electrode of Example 2;
17 is a diagram illustrating a half-cell structure.
18 is a diagram showing the structure of a full-cell.

Hereinafter, embodiments of the present invention will be described in detail. However, this is provided as an example, and the present invention is not limited thereto, and the present invention is only defined by the scope of the claims to be described later.

In this specification, the terminology used is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. In the present specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

When a part, such as a layer, film, region, plate, etc., is “on” or “on” another part, it includes not only cases where it is “directly on” another part, but also cases where there is another part in between. In addition, throughout the specification, "on" means to be located above or below the target portion, and does not necessarily mean to be located above the direction of gravity.

In this specification, the metal layer is used in the sense of including a plate-shaped (plate shape) metal having a thickness and an area.

In the present specification, the network structure means that particles have a form in which they are physically interconnected. As such, when the active material particles are physically interconnected, a connection between the active material particles may be formed electrically.

In the present specification, the alloying material absorbs sodium by electrochemically reacting with an alkali metal or alkaline earth metal such as sodium and alloying, and electrochemically emitting sodium or the like by dealloying to electrochemically absorb sodium, etc., material that can be released. These alloying materials (metal active materials) are gallium (Ga, gallium), germanium (Ge, germanium), indium (In, indium), tin (Sn, tin), antimony (Sb, antimony), thallium (Tl, thallium), It may be one selected from the group including lead (Pb, lead), bismuth (Bi, bismuth), and alloys thereof. However, it is not limited to the metals listed above, and metals capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal may be included therein.

The material that can be absorbed and released through the alloying and dealloying reaction with the alloying material may be an alkali metal or an alkaline earth metal, and the alloying and dealloying reaction has the following chemical reaction formula.

xA+ M ↔ A _x M

In the above chemical formula, A is an alkali metal or alkaline earth metal, and M is an alloying material.

At this time, since most of the values of x exceed 1, most of the alloyed materials show high theoretical capacity.

For example, when tin reacts with sodium _{to form the final product Na 15} Sn ₄ (x=3.75), it exhibits a high theoretical capacity of 847 mAh/g. Table 1 below shows the sodium reaction products and theoretical capacity according to the type of alloying material.

Referring to Table 1 below, it can be seen that the ion capacity of the alloying material may vary depending on the type of the alloying material. In addition, the alloying material may have a different capacity (capacity) depending on the degree of sodium (sodium).

cathode material
(Anode material) Sodium products
(Sodiation product) theoretical capacity
(Theoretical capacity) Ga Na _0.56 Ga (Na ₂₂ Ga ₃₉ ) 217 Ge Na ₃ Ge 1106 In NaIn 233 Sn Na _3.75 Sn (Na ₁₅ Sn ₄ ) 847 Sb Na ₃ Sb 660 Tl Na ₆ Tl 787 Pb Na ₁₅ Pb ₄ 485 Bi Na ₃ Bi 385

However, this alloying material (M) expands in volume when alloyed with an alkali metal or alkaline earth metal such as sodium (A _x M), and returns to the original alloying material (M) during de-alloying and decreases in volume. Therefore, when the alloying material is applied as an electrode active material, alloying and de-alloying occur in the electrode active material during charging and discharging of the battery, and intrinsic problems of causing volumetric expansion and contraction in the alloying material make it That is, the volume change due to charging and discharging causes an internal stress in the alloying material, which leads to the generation of cracks in the electrode active material (layer), and finally the cracks grow, and the electrode active material (layer) This cleavage leads to a process in which the electrode active material is pulverized into smaller particles. Due to the pulverization of the electrode active material (layer), there is a problem in that the electrode active material (layer) is electrically disconnected from the current collector or the conductive material in the electrode. Thus, since electrons are not supplied from the current collector, it is put in a state in which an electrochemical reaction can no longer be performed, and as charging and discharging are repeatedly performed, a rapid decrease in capacity occurs. As a result, an electrode having an alloying mechanism has a short charge/discharge cycle life. In order to solve the pulverization problem due to a large volume change rate during charging and discharging of the electrode active material, a method of making the active material into fine particles may be considered. However, in the case of a process of pulverizing an active material into fine particles, there is a problem in that the electrode price increases due to complicated and expensive process costs. In addition, when a powder electrode active material is used, a polymer binder is used to fix the powder electrode active material to the current collector, and a conductive material for improving conductivity is further included. However, the polymer binder and the conductive material are materials that do not react electrochemically, and since the content of the active material in the electrode is reduced, the total capacity of the electrode is reduced.

In order to provide a space capable of accommodating the volume expansion of the electrode active material during charging and discharging, a porous structure can be designed using the same material and different materials as the electrode active material. However, even when a porous structure is designed using a homogeneous material, there is a problem in that a fine powdering technique is required, thereby complicating the manufacturing process. In addition, when a porous structure is designed using a dissimilar material, an electrochemically non-reactive material is added to the electrode, thereby reducing the overall capacity of the electrode.

In addition, since the electrode using the powder has a low tap density, a compression process is necessarily performed. Even after the compression process, the processing density of the electrode using the powder is inevitably lower than that of an electrode made of a single mass, and fine particles It is also generally very difficult to increase the working density of electrodes including these. For the same reason, it is difficult to increase the thickness to improve the electrode loading per area.

Moreover, even if all of the above methods are used, the problems of pulverization of the electrode active material layer due to volume change occurring during the charge/discharge cycle, which are essential problems, a decrease in capacity, and a decrease in cycle characteristics cannot be fundamentally solved.

The present application can provide an anode for a secondary battery having improved charge/discharge cycle characteristics due to a stable porous structure as well as realizing a high-capacity electrode by including an electrode active material having a high capacity.

In addition, it is possible to form an electrode active material layer having a porous structure in which fine electrode active material particles are interconnected without using a micronized electrode active material powder. can provide a way.

In addition, since it is possible to provide an electrode having a porous structure in which micro-sized electrode active material particles not necessarily including a conductive material and/or a binder are interconnected, battery capacity can be improved.

cathode

The negative electrode according to an embodiment of the present invention includes a porous metal layer including a metal capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal.

The porous metal layer has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with the alkali metal or alkaline earth metal may be a metal including an alloying material.

2 is a view showing the structure of the porous metal layer of the negative electrode according to an embodiment of the present invention. As described above, it can be seen that the porous metal layer of the negative electrode according to an embodiment of the present invention has a porous three-dimensional network structure in which rod-shaped metal active material particles are three-dimensionally interconnected. Such a three-dimensional network structure may have a structure continuously connected not only in the thickness direction (longitudinal direction) of the porous metal layer, but also in the area direction (transverse direction). By having such a structure, not only the case of applying a current collector in the form of a surface in contact with the entire area of the porous metal layer, but also, if necessary, the advantage of implementing a negative electrode to which a current collector in contact with only a part of the area of the porous metal layer is applied have.

In addition, by having such a structure, it is possible to easily configure a large-area electrode by connecting a plurality of cathodes in the area direction (transverse direction).

The porous metal layer may include a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal, thereby realizing a high capacity.

Specifically, the alkali metal or alkaline earth metal may be selected from the group consisting of Li, Na, Mg, K, or Ca.

The metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with the alkali metal or alkaline earth metal may be an alloying material. Specifically, the alloying material may be Ga, Ge, In, Sn, Sb, Tl, Pb, or Bi. Such metals have the advantage of realizing high theoretical capacity by alloying with alkali metals or alkaline earth metals.

Since the porous metal layer has a porous structure in which micro metal particles are interconnected, the porous metal layer itself may serve as an active material layer and a current collector. Accordingly, the negative electrode including the porous metal layer may further include a current collector, but is not limited thereto. The current collector may be copper, stainless steel, aluminum, a carbon-coated metal, carbon fiber, or carbon paper. . However, the present invention is not limited thereto, and may include those applicable to the technical common sense in the relevant technical field.

The negative electrode according to an embodiment of the present invention may have a porous three-dimensional network structure in which the porous metal layer is interconnected with rod-shaped metal microparticles.

As described above, when the alloying material is applied as the electrode active material, the active material layer may be crushed or the active material separated from the current collector due to a large volume change during charging and discharging, and the electrical connection of the active material layer may be broken. That is, as the number of times of charging and discharging increases, there is a problem in that electrode performance is remarkably deteriorated.

However, the porous metal layer of the present application may provide a space capable of accommodating the volume change during charging and discharging as described above. In addition, by increasing the specific surface area of the active material layer of the porous active material layer of the present application, it is possible to increase the contact area with the electrolyte, decrease the current per unit area, decrease the internal resistance, decrease the overvoltage, and improve the charge/discharge rate.

Even if the active material layer has a porous structure, cracking of the active material layer may occur due to a change in volume. However, the porous structure of the present application can significantly reduce the breakage of the active material particles and the structure of the active material layer due to the stability of the structure despite the volume change during charging and discharging, and improve the charging and discharging cycle characteristics.

Specifically, the porous metal layer of the negative electrode according to an embodiment of the present invention may have the following characteristics.

The porous metal layer may have an average pore diameter of 0.1 to 200 μm. Specifically, it may be 0.1 to 150 μm, 0.1 to 100 μm, 0.1 to 50 μm, 0.1 to 30 μm, 0.1 to 20 μm, 1 to 15 μm, 1 to 10 μm, or 1 to 5 μm.

The porous metal layer may have a porosity of 50 to 90% by volume. Specifically, it may be 60 to 90% by volume, 70 to 90% by volume, 70 to 85% by volume, or 72 to 81% by volume.

The metal microparticles may have an average diameter of 0.1 to 5 μm. Specifically, it may be 0.1 to 3 μm, 0.3 to 3 μm, 0.5 to 2 μm, or 0.5 to 1.5 μm.

The metal microparticles may have an average length of 0.5 to 20 μm. Specifically, it may be 0.5 to 15 μm, 0.5 to 10 μm, 0.5 to 5 μm, 0.5 to 3 μm, or 1 to 3 μm. If the length of the metal microparticles is too long, the possibility of structural breakage may increase because the volume expansion rate in the longitudinal direction during alloying is large.

By satisfying the above range, it is possible to reduce the occurrence of cracking of particles and contact points due to volume change during charging and discharging, and the problem of crushing the active material (layer) can be reduced.

The metal microparticles may have an average aspect ratio (length/diameter) of 1 to 10. Specifically, it may be 1 to 8, 1 to 7, 1 to 5, 1 to 3, 1.1 to 10, 1.1 to 9, 1.1 to 7, 1.1 to 4, or 1.1 to 3.

The rod-shaped micro-particles are randomly connected, and the particles at most of the contact points may have a structure having a bonding angle of greater than 0° and less than 180°. In this case, since the pressure applied to the contact point due to volume expansion during alloying (especially, expansion in the longitudinal direction of the rod-shaped particle) is reduced compared to the case where the angle is 180°, by reducing the breakage of the contact and the rod-shaped particle, the active material The pulverization of the (layer) can be suppressed and the charge/discharge cycle characteristics can be improved. This structure may be due to most of the contacts having an angle of 180° between particles disappear in a step of repeatedly performing charging and discharging in a half-cell, which will be described later.

In the present specification, the angle between particles means an angle formed by two or more rod-shaped particles with respect to the contact point, and in the case of a contact point where two particles are connected, it means a numerical value of the smaller angle.

In addition, it may have a structure in which five or less particles are mainly connected at the contact point where each rod-shaped micro particle is connected, and preferably, it may have a structure in which two to three particles are connected. As the number of rod-shaped micro particles connected at the contact point increases, the pressure applied to the contact point during volume expansion may increase, and the contact point forming an angle of 180° between the particles increases. The occurrence of cracking, and cracking of the porous structure may increase.

The active material layer of the negative electrode manufactured according to an embodiment of the present invention is formed by using a negative electrode including a metal layer to form a half-cell, and by repeatedly charging and discharging it, the metal layer is converted into a porous metal layer. By repeatedly charging and discharging the half-cell, the metal layer repeatedly contracts and expands, and the metal layer is caused by factors such as reaction heat generated during alloying and de-alloying, and resistance at the contact point generated during half-cell charging and discharging. In the sintering reaction, a solid bond is formed between the particles. In addition, in the process of repeated contraction and expansion, unstable contacts and particles are broken and attached to other particles, and the process of maintaining stable contacts and particles is repeated. Accordingly, it is expected that the finally obtained porous metal layer will have the very stable three-dimensional network porous structure of the present application having a solid contact point between the rod-shaped particles.

4 is a tin porous metal layer (Example 1) prepared according to an embodiment of the present application, and it can be confirmed that the rod-shaped particles have a porous three-dimensional network structure interconnected.

6 is a state in which the tin porous metal layer of Example 1 of FIG. 4 is alloyed with sodium, and the rod-shaped particles are enlarged due to expansion of the active material and the pore volume is reduced, but it can be confirmed that the structure is maintained without breaking. That is, it can be seen that the anode porous metal layer of the present application has a stable structure in which no structural breakage occurs even when the active material layer is expanded by alloying. In the negative electrode including the porous metal layer having such a stable structure, even if the number of charge and discharge increases, crushing, separation of the electrode active material (layer), and electrical disconnection of the active material layer can be significantly reduced, resulting in improved charge/discharge cycle characteristics can contribute to

The rod-shaped metal micro-particles are of a form in which micro-metal particles having a diameter smaller than the length of the metal micro-particles are attached to the surface, or micro-metal particles having a diameter smaller than the length of the metal micro particles are protruded from the surface of the metal micro particles. It may have a surface. Specifically, the average particle diameter of the fine metal particles may be 0.1 to 5 μm. As described above, by repeatedly charging and discharging the half-cell, it may be formed in the process of repeatedly shrinking and expanding the metal layer, and unstable contacts and particles are broken and attached to other particles.

Referring to FIG. 13 , it can be confirmed that the rod-shaped Bi micro-metal particles having an average diameter of 1.4 μm and an average length of 2.3 μm have a protruding shape of micro particles with an average particle diameter of 0.5 μm on the surface.

The porous metal layer may include 90 wt% or more of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100 wt% of the total porous metal layer. Specifically, it may be 90 to 100% by weight, 92 to 100% by weight, 95 to 100% by weight, 97 to 100% by weight, 99 to 100% by weight, or 99.5 to 100% by weight. In this case, since the active material content in the electrode is high, the electrode capacity can be improved.

The form of such a porous metal layer may be formed by the manufacturing method according to an embodiment of the present invention, but may not be limited thereto.

The porous metal layer of the present invention has a three-dimensional porous structure in which micro particles are mutually aggregated, but the active material is finely powdered, and the shape of the particles is controlled to be applied as a composition or compressed to form a metal active material layer. , it is possible to form a porous metal layer composed of micro-sized active material particles having the above shape from the metal layer according to the manufacturing method of the present invention. Therefore, since the process for fine pulverization is not included, manufacturing cost can be reduced, and an active material layer that does not include a material that does not react electrochemically, such as a binder, and an electrode can be formed, thereby contributing to capacity improvement. can

In a specific embodiment of the present invention to be described later, an anode including a porous metal layer having a three-dimensional network structure in which Sn micro-particles are bonded to each other was manufactured. Looking at the surface SEM photograph of the porous metal layer according to the embodiment of the present invention, the porous metal layer of the embodiment provides a space that can sufficiently accommodate the change in the volume of the active material when Na ions are absorbed by the porous three-dimensional network structure in which the metal microparticles are interconnected. It was confirmed that the structure of the porous metal layer does not collapse even when alloyed. In addition, it was confirmed that the charge/discharge cycle characteristics could be maintained even though Sn, which had a large volume change during alloying, was applied as an active material.

The porous metal layer may include 90 wt% or more of a metal selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi based on 100 wt% of the total porous metal layer. Specifically, it may include one or more metals selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi.

As the remainder, other metals or unavoidable impurities may be included.

The content of the metal selected from the group comprising Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi is 97 to 100% by weight, 99 to 100% by weight, or 99.5 to 100% by weight based on 100% by weight of the entire porous metal layer. 100% by weight.

In the case of a porous metal layer prepared according to an embodiment of the present invention and an anode including the same, it does not contain a conductive material and/or binder that does not contribute to the electrode capacity unlike the active material layer prepared using conventional fine powder active material particles. can Therefore, the electrode capacitance can be improved.

The porous metal layer may include 90% by weight or more of the metal represented by the following Chemical Formula 1 based on 100% by weight of the total porous metal layer.

[Formula 1] A _x B

The x may be 0 to 6. Specifically, it may be more than 0, and 6 or less.

Specifically, the porous metal layer may include 90% by weight or more of the metal represented by the following Chemical Formula 2 or 3 based on 100% by weight of the total porous metal layer.

[Formula 2] Na _y Sn

[Formula 3] Na _z Bi

A may be an alkali metal and an alkaline earth metal.

B may be selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi.

The y may be 0 to 1. Specifically, it may be greater than 0, and less than or equal to 1.

The z may be 0 to 3. Specifically, it may be more than 0, and 3 or less.

In one specific embodiment of the present invention to be described later, the porous porous metal layer discloses a negative electrode including 100% by weight of Bi. Another embodiment of the negative electrode of the present invention discloses that the porous metal layer contains 92 wt% of Sn and Na as the balance.

The negative electrode according to an embodiment of the present invention may have a capacity retention rate of 95% or more after 80 times of charging and discharging. Specifically, it may be 95 to 100%, 95% or more and less than 100%, 99.3% or more and less than 100%, 99% to 99.9%, or 99.3% to 99.9%. The negative electrode according to an embodiment of the present invention may have a capacity retention rate of 95% or more after 80 times of charging and discharging. Specifically, it may be 95 to 100%, 95% or more and less than 100%, 99.3% or more and less than 100%, 99% to 99.9%, or 99.3% to 99.9%.

The negative electrode according to an embodiment of the present invention may have a capacity of 80% or more of a theoretical capacity. Specifically, it may be 80% to 100%, 80% or more, and less than 100%, 80% to 99.9%, or 85% to 99.9%.

Secondary battery manufacturing method

A secondary battery manufacturing method according to an embodiment of the present invention comprises: configuring a half-cell including a negative electrode including a porous metal layer, and a metal electrode; converting the metal layer into a porous metal layer by charging and discharging the half-cell two or more times; and manufacturing a full-cell including the negative electrode converted to the porous type, the positive electrode including the positive electrode active material, and the electrolyte. The porous metal layer includes a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal, and the metal electrode includes an alkali metal or alkaline earth metal.

The metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with the alkali metal or alkaline earth metal may be one selected from the group including Ga, Ge, In, Sn, Sb, Tl, Pb, Bi. have.

The alkali metal or alkaline earth metal may include one selected from the group consisting of Li, Na, and Mg.

In this case, the negative electrode according to an embodiment of the present invention can realize a high capacity by alloying and de-alloying with an alkali metal or alkaline earth metal.

In the step of configuring the half-cell, the half-cell may have a structure as shown in FIG. 17 .

In the step of manufacturing the full-cell, the full-cell may have a structure as shown in FIG. 18 .

In the step of converting the metal layer into the porous metal layer, the number of times of charging and discharging and the porous structure of the porous metal layer to be formed may vary depending on the type of metal included in the metal layer and the type of the metal electrode.

In the step of converting the metal layer into the porous metal layer, the porous metal layer may be converted into a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected. In this case, there is an advantage in that the active material layer composed of micro-sized active material particles can be manufactured without a high-cost and complicated process of finely pulverizing the active material and manufacturing the electrode active material layer using the fine powder.

The step of converting the metal layer into the porous metal layer may be to perform a cycle of full charge and full discharge by electrically connecting the cathode and the metal electrode.

In this case, in the half-cell, the cathode including the metal layer may be disposed on the anode, and the metal electrode may be disposed on the cathode to constitute the half-cell.

The volume expansion amount of the metal layer varies depending on the amount of alkali metal ions or alkaline earth metal ions absorbed and released during charging and discharging.

Accordingly, when the filling amount is too small, the volume change of the metal layer is too small to cause cracks in the metal layer, or the crack generation amount is small, so that the conversion into the porous metal layer is not achieved, or the conversion efficiency may be significantly lowered.

In the case of performing full charge and full discharge, it is possible to prepare a porous metal layer having a three-dimensional network structure in which micro-sized particles are interconnected even for a short time and a small number of charge and discharge.

In addition, in the case of an exemplary embodiment of the present invention, even if charging and discharging are repeatedly performed through full charging and full discharging, the horizontal complete fracture of the metal layer may not occur. This is because even if the porous metal layer having high surface energy and diffusion coefficient is cracked or crushed, room temperature sintering may occur in a limited space between the current collector and the separator. In addition, since the negative electrode including the metal layer includes a separator between the metal electrode as the counter electrode and consists of a half-cell to perform charging and discharging, the current collector and the microscopic size even when cracks occur due to the contraction and expansion of the metal layer. The limited space of the separator having pores prevents separation of the metal layer and the metal active material particles, and can support the shape of the metal layer.

configuring the half-cell; It may further include the step of manufacturing a cathode including a metal layer before.

The method of forming the metal layer may be by rolling, plating, sputtering, or aerosol.

The manufacturing of the negative electrode including the porous metal layer may include manufacturing the negative electrode including the metal layer by rolling the metal foil. In this case, a metal layer can be easily formed on the current collector, a metal layer of a desired thickness and area can be easily formed, metal fragments can be easily recycled by pressure welding, and an electrode capacity can be easily designed. have.

In addition, the capacity and energy of the battery are determined by the electrode, and since the thickness of the electrode means the specific gravity of the electrode in the battery, as the thickness of the electrode increases, the capacity and energy of the battery may increase.

However, when a thick metal layer is to be formed by the plating method, since the concentration of the dissolved metal ions is reduced in the process of reducing the metal ions dissolved in the solution, additional control is required to increase the thickness, homogeneity, and density. There are disadvantages. On the other hand, when the metal layer is formed by rolling, there is an advantage in that the thickness of the metal layer can be easily controlled, and a thick metal layer can be easily formed.

The manufacturing of the negative electrode may be to form a metal layer to a thickness of 25 μm to 2 mm. Since the shape and thickness can be changed through the step of assembling a half-cell after the step of manufacturing the negative electrode and converting the metal layer into a porous metal layer, the thickness of the metal layer formed in the step of manufacturing the negative electrode is determined by the following steps. It needs to be set taking into account.

If the thickness of the metal layer is too thin, the electrode may be easily torn, and the electrode may be completely broken due to the pores. If the thickness is too thick, it is difficult to expand the inside of the metal active material, and since the ion transfer may be very slow, the electrochemical reaction, that is, the charge/discharge rate may be significantly reduced.

secondary battery

A secondary battery according to an embodiment of the present invention includes a positive electrode; electrolyte; and a negative electrode according to an embodiment of the present invention.

Specifically, the negative electrode includes a current collector and a porous metal layer including a metal capable of absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal.

The porous metal layer has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected.

The electrolyte may include a metal salt and an ether-based solvent. Specifically, the metal salt may be selected from the group consisting of NaPF ₆ , NaClO ₄ , NaCF ₃ SO ₃ , NaBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiBF ₄ , and LiTFSI.

The ether-based solvent may be selected from the group consisting of DME, TEGDME, DEGDME, PEGDME, and PEO.

Specifically, dimethoxyethane (DME), 1,3-dioxolane (1,3-dioxolane), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (Diethylene glycol dimethyl ether) , DEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (Polyethylene glycol dimethyl ether, PEGDME), polyethylene oxide (Polyethleneoxide, PEO) and mixtures thereof may be selected from the group consisting of have. When the solvent is included, it is possible to suppress the formation of SEI on the metal surface, improve ionic conductivity, and improve stability with respect to an electrode made of an alkali metal and an alkaline earth metal.

The anode is CuS. Cu ₂ S, NiS, Ni ₃ S ₂ , NiS ₂ , TiS ₂ , and MoS ₃ may be selected from the group consisting of.

The secondary battery according to an embodiment of the present invention may further include a separator between the positive electrode and the negative electrode.

The separation membrane may be a nanopore separation membrane.

The nanopore separation membrane may have pores of 10 nm to 100 nm.

When the above range is satisfied, the metal layer particles pulverized according to battery charging and discharging may serve as a physical barrier to prevent separation from the negative electrode. Accordingly, the pulverized metal layer particles may be attached to the metal layer to continuously serve as an active material, and the charge/discharge cycle life may be improved. If the pores of the separator are too large, the pulverized metal layer particles may be separated or separated from the negative electrode, thereby reducing cycle characteristics. If the pores of the separator are too small, it is difficult to impregnate the electrolyte and the contact area between the electrolyte and the electrode is reduced. Ion transfer may not be smooth, and eventually, the ion conduction required for driving the battery may not be satisfied.

The thickness of the nanopore separator may be 5 μm to 1 mm. When the above range is satisfied, it acts as a sufficient physical barrier not to separate from the pulverized metal layer, thereby contributing to improvement of cycle characteristics.

In an embodiment of the present invention to be described later, Celgard 2400 (thickness 25 μm, pores 100 nm or less) was used as the nanopore separator.

The separation membrane may be a micropore separation membrane.

The micropore separation membrane may have pores of 1 μm to 50 μm.

The micropore separator may have a thickness of 0.2 mm to 2 mm.

When the above numerical range is satisfied, the micropore separator can prevent a short circuit inside the battery due to the formation of dendrites generated on the electrode surface during the charging and discharging process.

In an embodiment of the present invention to be described later, a glass fiber filter (thickness of about 1 mm, pores 10 μm or more) is used as the micropore separation membrane.

According to an embodiment of the present invention, a plurality of micropore separation membranes and/or micropore separation membranes may be included.

In an embodiment of the present invention to be described later, a triple separation membrane (Celgard 2400 / glass fiber filter / Celgard 2400) in which nanopore separation membranes are positioned on both sides of one micropore separation membrane, respectively, was used. Specifically, the nanopore separator may be in contact with each electrode, and the micropore separator may be positioned between the two nanopore separators.

In this case, the role of the glass fiber filter can delay the time of internal short circuit due to sodium metal or dendrites of the anode.

In addition, Celgard 2400 in contact with the anode can suppress the formation of dendrites on the anode.

Celgard 2400, which is in contact with the anode, prevents the metal layer particles pulverized into nanopores from being separated from the cathode, and can delay the internal short circuit caused by dendrite formation of the anode.

As a result, the charge/discharge cycle characteristics of the electrode can be improved.

Hereinafter, in order to help the understanding of the present invention, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited thereto.

Example 1: Cathode comprising Sn porous metal layer

In one specific embodiment of the present invention, Sn metal was rolled to form a Sn foil metal layer having a thickness of 27 μm, and a cathode having a diameter of 6 mm including a Sn foil metal layer was manufactured by punching it.

A half-cell was constructed using the negative electrode. Specifically, by connecting the cathode including the Sn foil metal layer and the Na metal electrode, charging and discharging 100 times by applying a current of 0.1 C-rate, the absorption and release of Na in the Sn foil metal layer are repeatedly performed to make Sn The foil metal layer was converted to a porous Sn porous metal layer.

The principle that the Sn foil metal layer is converted into the porous Sn porous metal layer is as follows.

During discharge, Na is absorbed into the Sn foil metal layer, and the volume expands. After charging, Na is released from the Sn foil metal layer and the volume shrinks again, so that the Sn foil metal layer is cracked and pulverized into small particles. The pulverized particles can recombine again to reduce the surface energy. The reason for recombination is believed to be that sintering occurs at the contact point between small particles. During this process, the pulverized particles form interconnected structures.

By repeatedly performing this charge (desodiation, causing volume shrinkage) and discharging (discharge: sodiation, causing volume expansion), the Sn foil metal layer contracts and expands repeatedly, and in this process, pulverization and recombination are repeated. happens A part with a mechanically unstable structure during contraction or expansion cracks or pulverizes again to become small particles, and these small particles recombine to form a new shape. On the other hand, the parts joined in a stable structure during contraction or expansion do not crack or pulverize even after repeated expansion and contraction and maintain their original shape. After sufficiently repeated charging and discharging, the porous metal layer has a stable structure against volume expansion-contraction. That is, the porous metal layer of the negative electrode according to an embodiment of the present invention reacts with sodium (discharge) to expand the volume, or the sodium escapes (charge: charge) so that even if the volume decreases, the occurrence of cracks or pulverization is significantly reduced Thus, a decrease in discharge capacity is suppressed even during repeated charging and discharging, and charging/discharging cycle characteristics can be improved. As such, a structure stable to volume expansion-contraction appears as a porous three-dimensional network structure in which rod-shaped Sn metal microparticles are interconnected in a unique way.

In the present specification, the network structure means that particles have a form in which they are physically interconnected. As such, when the active material particles are physically interconnected, a connection between the active material particles may be formed electrically.

The shape, particle size, or porosity of the porous metal layer may vary depending on the number of times of charging and discharging and the type of metal of the metal layer.

3 is an actual photograph of the porous metal layer of the negative electrode of Example 1; It can be confirmed that the porous metal layer has a three-dimensional network structure interconnected in the area and thickness directions of the electrode without visible cracks.

4 is a low magnification SEM photograph of the Sn porous metal layer of the negative electrode of Example 1; The average pore diameter is 2 μm, and the porosity of the active material layer is 81% by volume. The rod-shaped Sn micro-metal particles have an average diameter of 0.8 μm, an average length of 1.2 μm, and an aspect ratio (length/diameter) of the rod-shaped micro-particles is 1.3. In order to help the understanding of the structure of the porous metal layer, the direction of bonding of the rod-shaped metal particles at the contact point is indicated by a red arrow. It can be seen that the rod-shaped Sn micro-metal particles have a porous three-dimensional network structure by interconnecting in a random direction rather than a straight line in which the angle between the particles is 180 degrees. In particular, 1 to 5 rod-shaped particles are connected at each contact point (connection site) to form a three-dimensional porous structure. As described above, such a porous structure and porosity not only serves to provide a space that can accommodate the increased volume when the porous metal layer reacts with an alkali metal or alkaline earth metal to expand its volume, but also provides a structure stable for volume expansion. By having it, it is possible to reduce cracking or pulverization of active material particles or structures due to charging and discharging, and suppressing capacity reduction during charging and discharging cycles.

5 shows the EDS spectrum of the porous metal layer of the negative electrode of Example 1.

Example 1 The composition of the porous metal layer of the negative electrode is Na _0.08 Sn. That is, 92 wt% of Sn and the balance Na are included with respect to 100 wt% of the porous metal layer.

The Cu peak shown in FIG. 5 is a peak caused by the SEM holder, and the C peak and O peak correspond to peaks independent of the porous metal layer as a result of electrolyte or oxidation.

However, FIG. 5 is a measurement of the EDS spectrum of the porous metal layer in a state in which the negative electrode of Example 1 is not washed. It is understood that Na is due to the electrolyte or is not released and remains in the active material layer after being absorbed into the active material layer in the step of converting to the porous porous metal layer. That is, it is understood that the Sn content in the porous metal layer substantially exceeds 92% by weight based on 100% by weight of the porous metal layer.

6 is an SEM photograph of _{a state (full discharge, Na 3.75} Sn) in which the Sn porous metal layer of the negative electrode of Example 1 is electrochemically fully reacted with Na up to 1 mV. It can be seen that although the size and number of pores in the porous metal layer were reduced as the Sn metal microparticles were maximally expanded by reaction with Na, the pores were still secured. In particular, no cracks or crushed small particles can be observed despite the expansion in volume. That is, it can be seen that the porous active material layer of the anode of the present invention maintains a very stable structure without breakage or collapse of the structure despite volume expansion. Specifically, the Na _3.75 Sn active material layer of Example 1 had an average pore diameter of 0.5 μm and a porosity of 10% by volume. Accordingly, the porous metal layer of the negative electrode of Example 1 provides sufficient space to accommodate volume expansion due to reaction with alkali metal or alkaline earth metal, and at the same time provides an inherently stable internal stress that can be dispersed during volume expansion and contraction. It can be seen that the structure has

7 shows the EDS spectrum results of the porous metal layer of the negative electrode of Example 1 in a state (Na _{3.75 Sn) discharged with sodium to 1 mV.}

When the porous metal layer of the anode of the present invention reacts with sodium, the composition is expressed as Na _x Sn, and the range of x is possible up to 3.75.

The Cu peak shown in FIG. 7 is a peak caused by the SEM holder, and the C peak, O peak, P peak, and F peak are peaks independent of the porous metal layer as a result of electrolyte or oxidation.

8 is a charge/discharge graph of the negative electrode of Example 1.

The configuration of the battery shows the charging/discharging curve of the first cycle at a current of 0.1 C-rate by sequentially stacking a sodium metal counter electrode, a separator layer impregnated with an electrolyte, and the negative electrode of Example 1. Example 1 It can be seen that the negative electrode has both a charge capacity and a discharge capacity of 692 mAh/g, and it can be seen that it has a very reversible charge and discharge capacity.

This is because the rod-shaped metal microparticles have a interconnected porous three-dimensional network structure, which can reduce the interference between particles during volume expansion, the pores inside the electrode active material layer can accommodate the volume expansion, and access to the electrolyte It can be seen that this is due to the easy structure

9 shows an SEM photograph of the negative electrode of Comparative Example 1.

Example 1 In order to compare and confirm the effect according to the structure of the porous metal layer of the negative electrode, a porous tin negative electrode including the tin active material of Comparative Example 1 was prepared using tin powder. Specifically, it was prepared in the form of pellets compressed to 15 tons in a 50mm x 1.5mm mold by mixing tin powder and NaCl powder having 150 nm particles. Thereafter, by removing NaCl with distilled water, a porous electrode composed of only the tin active material of Comparative Example 1 was prepared.

Referring to FIG. 9 , it can be confirmed that tin particles having an average diameter of 150 nm and these particles were aggregated with each other to form a porous tin anode having a structure in which secondary particles of 500 to 1 μm and pores of 200 to 1 μm coexist. .

10 is a graph showing the charging and discharging characteristics at 0.1 C-rate of Comparative Example 1.

After constructing the same battery as in FIG. 8 of Example 1 using the electrode of Comparative Example 1, a charge/discharge test was performed at 0.1 C-rate. The maximum discharge capacity was 1.3 mAh/g, and no charging was performed. In addition, it can be seen that this discharge capacity is significantly lower than the charge/discharge capacity of 692 mAh/g shown in FIG. 8 .

11 is a graph showing cycle characteristics of the negative electrode of Example 1 and the negative electrode of Comparative Example 1; Example 1 The negative electrode had an initial capacity of 692 mAh/g for 80 cycles, a maximum capacity of 757 mAh/g during the cycle, and a minimum capacity of 601 mAh/g. That is, in the case of Example 1, a capacity of 600 mAh/g or more was shown for 80 cycles, which corresponds to about 1.6 to 2 times the theoretical capacity of 372 mAh/g of the conventional graphite anode for lithium ion batteries. In the case of the negative electrode of Example 1, it can be seen that the capacity retention rate after 80 charging and discharging is 99.3%, which has excellent cycle characteristics.

On the other hand, it can be seen that the negative electrode of Comparative Example 1 is discharged at about 1 mAh/g for 6 cycles, and charging does not occur. It can be seen that although the electrode of Comparative Example 1 includes a Sn active material layer having a porous structure, the structure of the active material layer cannot be maintained due to volume change due to charging and discharging, and cracks and pulverization occur.

That is, it can be seen that the active material layer of the negative electrode of Example 1 according to one embodiment of the present application has a stable porous structure of a tight bond as described above, and thus is a high-capacity negative electrode with improved charge/discharge cycle characteristics. Specifically, in the case of Example 1, four or less columnar tin particles are combined in random directions at each contact point between the columnar particles, so it can be confirmed that stress can be effectively dispersed during volume expansion. However, the negative electrode of Comparative Example 1 has a structure in which stress dispersion is difficult because a plurality of particles are bonded in several directions so that the bonding sites of the metal particles are indistinguishable, and more than four particles are bonded to the plurality of bonding sites. That is, it can be seen that even an electrode having a simple porous structure is difficult to maintain a stable structure by effectively dispersing stress during expansion.

Example 2: Anode comprising Bi porous metal layer

Bi metal was rolled to a thickness of 2 mm to form a Bi metal foil layer, and this was punched to prepare a 5 X 5 mm rectangular cathode including a Bi foil metal layer.

A half-cell was constructed using the negative electrode. Specifically, the cathode including the Bi foil metal layer and the Na metal electrode were connected. By applying a current of 0.01 C-rate and charging and discharging 4 times, the Bi foil metal layer was converted into a Bi porous metal layer.

12 is an actual photograph of the Bi porous metal layer of the negative electrode of Example 2; It can be seen that no visible cracks were found in the porous metal layer.

13 is a SEM photograph of the Bi porous metal layer of the negative electrode of Example 2. The average pore diameter is 2 μm, and the porosity of the active material layer is 72% by volume. The rod-shaped Bi micro-metal particles had an average diameter of 1.4 μm, an average length of 2.3 μm, and an aspect ratio (length/diameter) of the rod-shaped micro-particles was 1.6. In addition, it can be confirmed that the rod-shaped Bi micro-metal particles are interconnected in random directions to have a porous three-dimensional network structure. At each contact point (connection site), 1 to 5 rod-shaped particles are connected to form a three-dimensional porous structure. As described above, such a porous structure and porosity can contribute to improving electrode cycle characteristics by providing a space that can accommodate an increased volume when the porous metal layer reacts with an alkali metal or alkaline earth metal to expand the volume. More specifically, it can be seen that the rod-shaped Bi micro-metal particles have a protruding shape with an average particle diameter of 0.5 μm on the surface.

14 is an XRD pattern of the porous Bi porous metal layer of the negative electrode of Example 2; It agrees very well with the bismuth crystal peak of JCPDS #85-1329 used for XRD analysis, and no additional peaks are observed. Accordingly, it can be seen that the Bi porous metal layer is made of only Bi.

15 is a charge/discharge graph of the negative electrode of Example 2.

The configuration of the battery shows the charging/discharging curve of the first cycle at a current of 0.1 C-rate by sequentially stacking a sodium metal counter electrode, a separator layer impregnated with an electrolyte, and a negative electrode of Example 2. The graph shows the charge/discharge graph at 0.01 C-rate of the first cycle. Example 2 It can be seen that the negative electrode has a charge capacity of 366 mAh/g and a discharge capacity of 352 mAh/g, and has a very reversible charge and discharge capacity.

This is because the rod-shaped metal microparticles have a interconnected porous three-dimensional network structure, which can reduce the interference between particles during volume expansion, the pores inside the electrode active material layer can accommodate the volume expansion, and access to the electrolyte It can be seen that this is due to the easy structure

16 is a graph showing the cycle characteristics of the negative electrode of Example 2 1 to 100 times. Charging and discharging proceeded at a current of 0.1 C-rate, with an initial capacity of 330 mAh/g, 330 mAh/g after 100 cycles, and an average capacity of 340 mAh/g, which is 85% of the theoretical capacity. In addition, it can be seen that the discharge capacity is maintained even after 100 cycles, and the capacity retention rate is 99.8%.

The present invention is not limited to the above embodiments, but can be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains can take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (17)

A porous metal layer comprising a metal capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and de-alloying with an alkali metal or alkaline earth metal;
The porous metal layer has a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected, and the rod-shaped metal microparticles have a structure in which the particles have a bond angle of greater than 0° and less than 180° at the contact point,
The porous metal layer does not contain a binder,
The negative electrode of which the capacity retention rate is 95% or more after 80 times of charging and discharging.
According to claim 1,
The porous metal layer has an average pore diameter of 0.1 to 200 μm, a negative electrode.
According to claim 1,
The porous metal layer has a porosity of 50 to 90% by volume, the anode.
According to claim 1,
The metal microparticles have an average diameter of 0.1 to 5 μm, the cathode.
According to claim 1,
The metal microparticles have an average length of 0.5 to 20 μm, the cathode.
According to claim 1,
The metal microparticles have an average aspect ratio (length/diameter) of 1 to 10.
According to claim 1,
The porous metal layer is Ga, Ge, In, Sn, Sb, Tl, Pb, and the negative electrode comprising at least 90% by weight based on 100% by weight of the total porous metal layer of a metal selected from the group including Bi.
According to claim 1,
Wherein the porous metal layer comprises 90 wt% or more of the metal represented by the following formula (1) based on 100 wt% of the total porous metal layer, the anode:
[Formula 1]
A _x B
Wherein A is Li, Na, Mg, K, or Ca,
Wherein B is selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi,
wherein x is 0 to 6.
According to claim 1,
Wherein the porous metal layer comprises 90% by weight or more of the metal represented by Formula 2 or Formula 3 based on 100% by weight of the total porous metal layer, the negative electrode:
[Formula 2]
Na _y Sn
[Formula 3]
Na _z Bi
Wherein y is 0 to 1,
The z is 0 to 3.
constructing a half-cell including a cathode including a metal layer and a metal electrode;
converting the metal layer into a porous metal layer by charging and discharging the half-cell two or more times; and
A negative electrode including the porous metal layer, a positive electrode including a positive electrode active material, and a full-cell including an electrolyte,
The metal layer contains a metal capable of reversibly absorbing and releasing alkali metal or alkaline earth metal ions by alloying and dealloying with an alkali metal or alkaline earth metal,
The metal electrode comprises an alkali metal or alkaline earth metal,
In the step of converting the metal layer into a porous metal layer,
The porous metal layer is converted into a porous three-dimensional network structure in which rod-shaped metal microparticles are interconnected, and the rod-shaped metal microparticles have a bonding angle of greater than 0° and less than 180° at the contact point,
The porous metal layer does not contain a binder,
Which further comprises the step of manufacturing a negative electrode including a metal layer by rolling a metal foil before the step of forming the half-cell,
A method for manufacturing a secondary battery.
11. The method of claim 10,
The step of converting the metal layer into a porous metal layer,
By electrically connecting the cathode and the metal electrode, the cycle proceeds with full charge and complete discharge,
A method for manufacturing a secondary battery.
delete delete 11. The method of claim 10,
The step of preparing the negative electrode is
To form a metal layer to a thickness of 25 μm to 2 mm,
A method for manufacturing a secondary battery.
anode;
electrolyte; and
According to any one of claims 1 to 9, comprising the negative electrode of any one of
secondary battery.
16. The method of claim 15,
The electrolyte will include a metal salt, and an ether-based solvent.
secondary battery.
17. The method of claim 16,
The ether solvent is dimethoxyethane (DME), 1,3-dioxolane (1,3-dioxolane), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (Diethylene glycol) dimethyl ether, DEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol dimethyl ether (PEGDME), polyethylene oxide (PEO), and mixtures thereof. that is,
secondary battery.

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