KR102282912B1 - Anode, secondary battery including the same, and manufacturing method thereof - Google Patents

Abstract

A negative electrode according to an embodiment of the present invention includes a current collector including a first metal; and an alloy active material layer comprising an alloy of a first metal and a second metal, wherein the first metal included in the current collector and the alloy active material layer is the same metal, and the first metal is Ga, Ge, In, Sn, Sb, Tl, Pb, and selected from the group containing Bi, the second metal is selected from the group containing Na, Li, and Mg, the alloy active material layer is represented by any one of Formulas 1 to 24 including alloys that become

Description

Anode, secondary battery including same, and method for manufacturing the same {ANODE, SECONDARY BATTERY INCLUDING THE SAME, AND MANUFACTURING METHOD THEREOF}

It relates to a negative electrode including an alloy active material 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 secondary battery including the same, and a method for manufacturing 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 was devised to solve the above problems, and to provide a negative electrode including an alloy active material layer having a high capacity and excellent cycle characteristics, a secondary battery including the same, and a manufacturing method thereof.

A negative electrode according to an embodiment of the present invention includes a current collector including a first metal; and

and an alloy active material layer including an alloy of the first metal and the second metal.

The first metal included in the current collector and the alloy active material layer may be the same metal.

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

The second metal may be selected from the group consisting of Na, Li, and Mg.

The alloy active material layer may include an alloy represented by any one of the following Chemical Formulas 1 to 24.

[Formula 1]

Na _a Ga

0 < a < 1/4

[Formula 2]

Na _b Ge

0 < b < 1

[Formula 3]

Na _c In

0 < c < 5/8

[Formula 4]

Na _d Sn

0 < d < 1

[Formula 5]

Na _e Sb

0 < e < 1

[Formula 6]

Na _f Tl

0 < f < 1/2

[Formula 7]

Na _g Pb

0 < g < 1

[Formula 8]

Na _h Bi

0 < h < 1

[Formula 9]

Li _i Ga

0 < i < 1/2

[Formula 10]

Li _j Ge

0 < j < 3

[Formula 11]

Li _k In

0 < k < 2

[Formula 12]

Li _l Sn

0 < l < 1

[Formula 13]

Li _m Sb

0 < m < 2

[Formula 14]

Li _n Tl

0 < n < 1

[Formula 15]

Li _o Pb

0 < o < 1

[Formula 16]

Li _p Bi

0 < p < 1

[Formula 17]

Mg _q Ga

0 < q < 1/2

[Formula 18]

Mg _r Ge

0 < r < 2

[Formula 19]

*Mg _s In

0 < s < 1/2

[Formula 20]

*Mg _t Sn

0 < t < 2

[Formula 21]

Mg _u Sb

0 < u < 3/2

[Formula 22]

Mg _v Tl

0 < v < 1

[Formula 23]

Mg _w Pb

0 < w < 2

[Formula 24]

Mg _y Bi

0 < y < 3/2

The current collector and the alloy active material layer may have an atomic bond connecting the current collector and the alloy active material layer.

The alloy active material layer may include 97 mass% or more of the alloy represented by any one of Formulas 1 to 24 based on 100 mass% of the alloy active material layer.

The alloy active material layer may have a plurality of columnar structures in which micro metal particles are stacked and bonded up and down.

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

The alloy active material layer may have a porosity of 50 to 90% by volume.

The thickness of the alloy active material layer relative to the current collector thickness (alloy active material layer thickness/current collector thickness) may be 0.01 to 200.

Compared to the one-cycle discharge capacity, the retention of the 100-cycle discharge capacity may be 95% or more.

Compared to the one-cycle discharge capacity, the retention of the 30-cycle discharge capacity may be 92% or more.

The difference between the one-cycle discharge capacity and the two-cycle discharge capacity may be 5%.

A secondary battery manufacturing method according to an embodiment of the present invention comprises: configuring a half-cell including a metal foil negative electrode and a metal electrode including an alkali metal or alkaline earth metal; forming an alloy active material layer on one surface of the metal foil negative electrode by discharging the half-cell to less than a boundary point of an initial flat voltage section on a discharge graph; and manufacturing a full-cell including a negative electrode having an alloy active material layer formed on one surface thereof, a positive electrode including a positive electrode active material, and an electrolyte.

The metal foil negative electrode may include a metal selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi.

In the step of forming the alloy active material layer, the discharge capacity may be controlled to less than 1107 mAh/g.

The step of forming the alloy active material layer may be to control the discharge capacity to satisfy Equation 1 below.

[Equation 1] 0 < 100 * (discharge capacity at the boundary of the initial flat voltage section/total theoretical discharge capacity at full discharge) < 100.

When the alkali metal is Li in the step of forming the alloy active material layer, the metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 226 mAh/g, or the metal foil is a Bi metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 128 mAh/g, or the metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 192 mAh/g, or the metal foil is a Ge metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 1623 mAh/g, or the metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 700 mAh/g, or the metal foil is an Sb metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 660 mAh/g, or the metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 525 mAh/g, or the metal foil is a Pb metal foil It is a negative electrode, and the discharge capacity may be controlled to be greater than 0, and less than 569 mAh/g.

When the alkali metal is Na in the step of forming the alloy active material layer, the metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 226 mAh/g, or the metal foil is a Bi metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 128 mAh/g, or the metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 96 mAh/g, or the metal foil is a Ge metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 369 mAh/g, or the metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 145 mAh/g, or the metal foil is an Sb metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 220 mAh/g, or the metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 65 mAh/g, or the metal foil is a Pb metal foil It is a negative electrode, and the discharge capacity may be controlled to be greater than 0, and less than 129mAh/g.

When the alkali metal is Mg in the step of forming the alloy active material layer, the metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 452 mAh/g, or the metal foil is a Bi metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 192 mAh/g, or the metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 192 mAh/g, or the metal foil is a Ge metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 738 mAh/g, or the metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 116 mAh/g, or the metal foil is an Sb metal foil a negative electrode, wherein the discharge capacity is controlled to be greater than 0 and less than 330 mAh/g, or the metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 131 mAh/g, or the metal foil is a Pb metal foil It is a negative electrode, and the discharge capacity may be controlled to be greater than 0, and less than 259mAh/g.

Before forming the half-cell, the method may further include forming a metal foil negative electrode by rolling a metal.

A secondary battery according to an embodiment of the present invention includes a positive electrode; electrolyte; and an anode 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), polyethyleneoxide (PEO), dioxolane (DOL) and these It may be selected from the group comprising a mixture of

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 separator may be a micro-pore separator 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.

By applying an alloy active material 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, the electrode capacity can be improved.

By controlling the composition of the alloy active material layer and the degree of alloying, the active material layer according to the volume change of the active material during charging and discharging suppresses cracking and pulverization, and improves cycle characteristics.

1 is a schematic diagram showing the structure of an electrode according to an embodiment of the present application.
2 is a diagram showing the structure of a half-cell.
3 is a discharge graph showing an electrochemical reaction section for preparing the negative electrode of Example 1;
4 is a photograph of the alloy active material layer of the negative electrode of Example 1.
5 is a photograph of the current collector of the negative electrode of Example 1.
6 is a SEM photograph of the alloy active material layer of the negative electrode of Example 1.
7 is an EDS spectrum of the negative electrode of Example 1.
8 is a graph showing the cycle characteristics of the negative electrode of Example 1 at a current density of 0.01 C.
9 shows a charge/discharge curve at a current density of 0.01 C of the negative electrode of Example 1.
10 is a photograph of the alloy active material layer of the negative electrode of Example 2;
11 is a photograph of the current collector of the negative electrode of Example 2.
12 is a charge/discharge curve at 0.01 C of the negative electrode of Example 2.
Fig. 13 is a discharge graph of the Bi electrode of Example 2;
14 is a graph showing cycle characteristics for 1 to 30 cycles of the Bi anode of Example 2;
15 is an actual photograph of the electrode of Example 1 ( _{a negative electrode including a Na 0.22} Sn alloy active material layer) after performing one charge/discharge cycle.
16 is an actual photograph of the electrode of Comparative Example 1.
17 is an actual photograph after removing the separator of the electrode of Comparative Example 2.
18 is an Sn electrode discharge graph.
19 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 part, and does not necessarily mean to be located above the direction of gravity.

In the present specification, the flat voltage section has a slope of -0.1 dv/d (mAh/g) to -0.1 dv/d (mAh/g) at any point within a micro-region of 1 mAh/g capacity in a normal continuous discharge process without voltage fluctuations due to polarization and voltage drop. It is defined as a voltage section continuously connected to 0.1dv/d (mAh/g). The initial flat voltage section is defined as a section that appears first during discharge among these sections. In other words, the flat voltage section is defined as a section in which the OCV (Open circuit voltage) is the same during the discharging process in the galvanostatic intermittent titration technique (GITT) experiment, until the OCV after 10 mAh/g remains the same after the start of discharging. is defined as the first flat voltage interval.

That is, when discharging is performed with a GITT that measures OCV while discharging, the same OCV appears in the same flat voltage section, so a section continuously having the same OCV can be viewed as a flat voltage section.

In the present specification, the boundary point of the first flat voltage section means a point at which the first flat voltage section that appears during discharge ends.

18 shows a discharge graph of a half-cell using Sn metal as an anode and Na metal as a cathode in order to help understand the flat voltage section. Referring to FIG. 18 , it can be confirmed that the first flat voltage section is the section in which the discharge capacity is 0 to 226 mAh/g-Sn, and the point of 226 mAh/g-Sn is the boundary point of the first flat voltage section.

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 occluding 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. Therefore, since electrons are not supplied from the current collector, it is placed 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 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 includes an electrode active material having a high capacity, thereby realizing a high-capacity electrode, as well as providing a negative electrode for a secondary battery having excellent contact properties and a strong bond between the current collector and the active material layer. As a result, the secondary battery to which such a negative electrode is applied may have improved charge/discharge cycle characteristics.

In addition, it is possible to form an alloy active material layer having a plurality of columnar structures in which fine electrode active material particles are stacked and bonded up and down without using the refined electrode active material powder, and a high-capacity high-capacity electrode with improved contact with the electrolyte at a low cost by a simple method. A negative electrode for a secondary battery and a method for manufacturing a battery including the same can be provided.

In addition, since the active material layer of the negative electrode for a secondary battery of the present application does not necessarily include a conductive material and/or a binder, battery capacity may be improved.

cathode

A negative electrode according to an embodiment of the present invention includes a current collector including a first metal, and an alloy active material layer including an alloy of the first metal and the second metal.

The first metal included in the current collector and the alloy active material layer is the same metal, and the first metal is selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi, and the second metal The metal is selected from the group comprising Na, Li, and Mg.

The alloy active material layer includes an alloy represented by any one of the following Chemical Formulas 1 to 24.

[Formula 1]

Na _a Ga

(0 < a < 1/4 in Formula 1)

[Formula 2]

Na _b Ge

(0 < b < 1 in Formula 2)

[Formula 3]

Na _c In

(0 < c < 5/8 in Formula 3)

[Formula 4]

Na _d Sn

(0 < d < 1 in Formula 4)

[Formula 5]

Na _e Sb

(0 < e < 1 in Formula 5)

[Formula 6]

Na _f Tl

(0 < f < 1/2 in Formula 6)

[Formula 7]

Na _g Pb

(0 < g < 1 in Formula 7)

[Formula 8]

Na _h Bi

(0 < h < 1 in Formula 8)

[Formula 9]

Li _i Ga

(0 < i < 1/2 in Formula 9)

[Formula 10]

Li _j Ge

(0 < j < 3 in Formula 10)

[Formula 11]

Li _k In

(0 < k < 2 in Formula 11)

[Formula 12]

Li _l Sn

(0 < l < 1 in Formula 12)

[Formula 13]

Li _m Sb

(0 < m < 2 in Formula 13)

[Formula 14]

Li _n Tl

(0 < n < 1 in Formula 14)

[Formula 15]

Li _o Pb

(0 < o < 1 in Formula 15)

[Formula 16]

Li _p Bi

(0 < p < 1 in Formula 16)

[Formula 17]

Mg _q Ga

(0 < q < 1/2 in Formula 17)

[Formula 18]

Mg _r Ge

(0 < r < 2 in Formula 18)

[Formula 19]

Mg _s In

(0 < s < 1/2 in Formula 19)

[Formula 20]

Mg _t Sn

(0 < t < 2 in Formula 20)

[Formula 21]

Mg _u Sb

(0 < u < 3/2 in Formula 21)

[Formula 22]

Mg _v Tl

(0 < v < 1 in Formula 22)

[Formula 23]

Mg _w Pb

(0 < w < 2 in Formula 23)

[Formula 24]

Mg _y Bi

(0 < y < 3/2 in Formula 24)

1 is a view showing a negative electrode according to an embodiment of the present invention. It has a structure in which a current collector including a first metal, and an alloy active material layer including an alloy of the first metal and the second metal are positioned on the current collector.

The current collector and the alloy active material layer may have an atomic bond.

The negative electrode manufactured according to an embodiment of the present invention is manufactured by forming an alloy active material layer on one surface of the first metal foil, and the active material composition including a binder is applied on the current collector, or an active material layer prepared separately It is not attached to the current collector. That is, in the negative electrode of the present application, the current collector and the active material layer are initially bonded to atoms in the same material, and even after the active material layer is formed, the atomic bond between the current collector and the active material layer is not completely broken. Therefore, since the adhesive force between the current collector and the alloy active material layer is strong, it is possible to suppress the separation of the active material layer from the current collector, and there are advantages in that the cycle characteristics are excellent and the contact characteristics at the interface are excellent.

The first metal is a metal capable of absorbing and releasing the second metal by alloying and de-alloying with the second metal. Specifically, the first metal may be selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi. The second metal may be selected from the group consisting of Na, Li, and Mg.

The above-described first metals have the advantage of being able to implement a high capacity by alloying with an alkali metal or alkaline earth metal. However, due to a large volume change during alloying with alkali metals or alkaline earth metals, cracks occur in the active material layer during repeated charging and discharging, and the electrical connection of the active material layer is broken due to pulverization, or the cycle characteristics are lowered by falling off from the current collector. there is a problem that

According to one embodiment of the present invention, by applying a negative electrode comprising an alloy active material layer represented by Chemical Formulas 1 to 24, cracks are generated due to repeated charging and discharging and the active material particles and/or the active material layer are pulverized to form the active material layer. It can solve the problem of electrical disconnection.

The alloy active material layer may include 97 mass% or more of the alloy represented by any one of Formulas 1 to 24 based on 100 mass% of the alloy active material layer. Specifically, 97 to 100 mass%, 99 to 100 mass%, 99.7 to 100 mass%, 97 mass% or more and less than 100 mass%, 99 mass% or more, and 100 mass% of the alloy represented by any one of Formulas 1 to 24 Less than, or 99.7 mass% or more and less than 100 mass% may be included. In addition, unavoidable impurities or other metals may be included as the remainder.

As described above, the negative electrode according to the exemplary embodiment of the present invention does not include a material that does not react electrochemically, such as a binder or a conductive material, and is composed of almost 100% by mass of an active material, thereby increasing the total capacity of the electrode. In addition, there is an advantage in that the processing density is high compared to the active material layer prepared using the active material in powder form.

Specifically, the negative electrode according to an embodiment of the present invention, and an alloy active material layer thereof may have the following structure.

The alloy active material layer may have a plurality of columnar structures in which micro metal particles are stacked and bonded up and down.

The alloy active material 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, or 75 to 85% by volume.

The micro metal particles may have an average diameter of 0.1 to 5 μm. Specifically, it may be 0.1 to 3 μm, 0.1 to 2 μm, 0.2 to 1 μm, 0.2 to 0.8 μm, or 0.2 to 0.5 μm.

The shape of the alloy active material layer increases the specific surface area of the active material layer, thereby increasing the contact area with the electrolyte, thereby reducing the current per unit area, thereby reducing the internal resistance of the battery, reducing the overvoltage, and improving the charging/discharging speed.

The shape of the alloy active material layer may be formed by the manufacturing method according to an embodiment of the present invention, but may not be limited thereto.

The thickness of the alloy active material layer relative to the current collector thickness (alloy active material layer thickness/current collector thickness) may be 0.01 to 200. Specifically, it may be 0.1 to 180, or 0.5 to 160. The negative electrode manufactured according to an embodiment of the present invention is manufactured by forming an alloy active material layer on one surface of the first metal foil, and is discharged below the first flat voltage section boundary point on the discharge graph when the alloy active material layer is prepared by Formulas 1 to 24 According to a method of forming an alloy active material layer comprising an alloy selected from among. Accordingly, in the case of the negative electrode manufactured by the above-described manufacturing method, the negative electrode having the thickness of the alloy active material layer within the above range relative to the thickness of the current collector may be manufactured.

The negative electrode manufactured according to an embodiment of the present invention is manufactured by forming an alloy active material layer on one surface of the first metal foil, and the active material composition including a binder is applied on the current collector, or an active material layer prepared separately It is not attached to the current collector. That is, in the negative electrode of the present application, the current collector and the active material layer are initially bonded to atoms in the same material, and even after the active material layer is formed, the atomic bond between the current collector and the active material layer is not completely broken. Therefore, since the adhesive force between the current collector and the alloy active material layer is strong, it is possible to suppress the separation of the active material layer from the current collector, and there are advantages in that the cycle characteristics are excellent and the contact characteristics at the interface are excellent.

The negative electrode according to an embodiment of the present invention may have a retention ratio of 100 cycle discharge capacity compared to 1 cycle discharge capacity of 95% or more. Specifically, 97 to 100%. 98-100%, 99-100%, or 99.5-100%. Looking at the cycle characteristic graph of Example 1, which will be described later, it can be seen that the 100-cycle discharge capacity is maintained at almost 99% or more and close to 100% compared to the 1-cycle discharge capacity. This is because the current collector and the active material layer were initially bonded to atoms in the same material, and even if a new phase is formed by absorbing ions into the lattice of the active material layer, the bond between the atoms is maintained between the active material layer and the current collector.

The negative electrode according to the exemplary embodiment of the present invention may have a retention ratio of 85% or more of a discharge capacity of 30 cycles compared to a discharge capacity of 1 cycle. Specifically, 85 to 100%. 90-100%, 92-100%, or 93-100%.

The negative electrode according to the exemplary embodiment of the present invention may have a difference of 1 cycle discharge capacity and 2 cycle discharge capacity of 5% or less. Specifically, it may be greater than 0% and less than or equal to 5%, greater than or equal to 0% and less than or equal to 3%, greater than or equal to 0% and less than or equal to 1%, or greater than or equal to 0% and less than or equal to 0.3%.

Looking at the cycle characteristic graph of Example 1, which will be described later, it can be seen that the difference between the 1 cycle discharge capacity and the 2 cycle discharge capacity is close to 0%. This is believed to be because the activation of the active material layer is completely terminated in one cycle, and charging and discharging are performed while the current collector and the active material layer maintain the bond between atoms from the second cycle.

Secondary battery manufacturing method

A method of manufacturing a secondary battery according to an embodiment of the present invention comprises: configuring a half-cell including a metal foil negative electrode and a metal electrode including an alkali metal or alkaline earth metal; forming an alloy active material layer on one surface of the metal foil negative electrode by discharging the half-cell to less than a boundary point of an initial flat voltage section on a discharge graph; and manufacturing a full-cell including a negative electrode having an alloy active material layer formed on one surface thereof, a positive electrode including a positive electrode active material, and an electrolyte.

The metal foil negative electrode may include a metal selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi.

The forming of the half-cell may include disposing a metal foil negative electrode on the positive electrode and disposing a metal electrode including an alkali metal or alkaline earth metal on the negative electrode to configure the half-cell.

At this time, the metal foil negative electrode is alloyed with an alkali metal or alkaline earth metal to form an alloy active material layer on one surface of the metal foil negative electrode.

2 illustrates a structure of a half-cell as an example.

The forming of the alloy active material layer on one surface of the metal foil negative electrode may include discharging the half-cell below a boundary point of an initial flat voltage section on a discharge graph.

In the step of forming the alloy active material layer, the discharge capacity may be controlled to less than 1107 mAh/g.

The discharge capacity at the boundary point of the initial flat voltage section and the total theoretical discharge capacity during full discharge may vary according to the types of the first metal and the second metal. Specific values for each metal are shown in Table 2 below.

If the discharge is too much, cracks may occur in the metal foil negative electrode, which may deteriorate the cycle characteristics of the electrode and cause a problem in which the current collector is completely transformed into an active material layer. If the discharge is too small, the usable capacity may decrease. When discharging below the boundary point of the initial flat voltage section, an alloy active material layer in which cracks do not occur may be formed. If cracks do not occur, since electrons can easily move in any direction of the active material layer, it may be easy for all atoms of the active material layer to react.

Specifically, the step of forming the alloy active material layer may be to control the discharge capacity to satisfy Equation 1 below.

[Equation 1] 0 < 100 * (discharge capacity at the boundary of the initial flat voltage section/total theoretical discharge capacity at full discharge) < 100.

Li Na Mg x value in A _{x M} (When fully discharged) Total discharge capacity
(mAh/g) Discharge capacity at the boundary point of the first flat voltage section flat voltage section
(mAh/g) Calculation 1 x value in A _{x M} (When fully discharged) Total discharge capacity
(mAh/g) Discharge capacity at the boundary point of the initial flat voltage section flat voltage section
(mAh/g) Calculation 1 x value in A _{x M} (When fully discharged) Total discharge capacity
(mAh/g) Discharge capacity at the boundary point of the initial flat voltage section flat voltage section
(mAh/g) Calculation 1 Sn <1 993 226 <22.7 <1 847 226 <26.7 <2 452 452 <100 Bi <1 385 128 <33.3 <1 385 128 <33.3 <3/2 192 192 <100 Ga <1/2 769 192 <25 <1/4 217 96 <44.3 <1/2 961 192 <20 Ge <3 1623 1107 <68.2 <1 1107 369 <33.3 <2 738 738 <100 In <2 700 467 <66.7 <5/8 233 145 <62.5 <1/2 664 116 <17.6 Sb <2 660 440 <66.7 <1 660 220 <33.3 <3/2 330 330 <100 Tl <1 525 131 <25 <1/2 787 65 <8.3 <1 328 131 <40 Pb <1 569 129 <22.7 <1 485 129 <26.7 <2 259 259 <100

_{In A x} M of Table 2, A is the second metal, and M is the first metal.

According to the type of the first metal and the second metal, there may be one or more flat voltage sections in the discharge graph. For example, when the second metal is magnesium (Mg) and the first metal is Sn, Bi, Ge, Sb, or Pb, the flat voltage section may be one flat voltage section. As described above, when there is one flat voltage section flat voltage section, the discharge capacity is the first flat voltage section flat voltage section boundary point at the point at which the flat voltage section flat voltage section ends (that is, the point at which the flat voltage section is completely discharged). That is, in this case, the step of forming the alloy active material layer may be controlled to be less than the point of complete discharge.

In the step of forming the alloy active material layer, when the alkali metal is Li,

wherein the metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 226 mAh/g, or the metal foil is a Bi metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 128 mAh/g; or , wherein the metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 192 mAh/g, or the metal foil is a Ge metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 1623 mAh/g, or , wherein the metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 700 mAh/g, or the metal foil is an Sb metal foil negative electrode, and the discharge capacity is controlled to greater than 0 and less than 660 mAh/g; or , wherein the metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 525 mAh/g, or the metal foil is a Pb metal foil negative electrode, and the discharge capacity is controlled to more than 0 and less than 569 mAh/g it could be

When the alkali metal is Na in the step of forming the alloy active material layer,

wherein the metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 226 mAh/g, or the metal foil is a Bi metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 128 mAh/g; or , wherein the metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 96 mAh/g, or the metal foil is a Ge metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 369 mAh/g, or , wherein the metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 145 mAh/g, or the metal foil is an Sb metal foil negative electrode, and the discharge capacity is controlled to more than 0 and less than 220 mAh/g; or , wherein the metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 65 mAh/g, or the metal foil is a Pb metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 129 mAh/g it could be

When the alkali metal is Mg in the step of forming the alloy active material layer,

wherein the metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 452 mAh/g, or the metal foil is a Bi metal foil negative electrode, and the discharge capacity is controlled to more than 0 and less than 192 mAh/g; or , wherein the metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 192 mAh/g, or the metal foil is a Ge metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 738 mAh/g, or , wherein the metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 116 mAh/g, or the metal foil is an Sb metal foil negative electrode, and the discharge capacity is controlled to more than 0 and less than 330 mAh/g; , wherein the metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0 and less than 131 mAh/g, or the metal foil is a Pb metal foil negative electrode, and the discharge capacity is controlled to more than 0 and less than 259 mAh/g it could be

In the step of forming the alloy active material layer, the discharge current may be controlled to 0.01 C-rate to 1 C-rate. Specifically, the discharge current can be controlled to a discharge time at 0.01 C-rate to 0.1 C-rate. If the discharge current is too large, the alloying reaction of the metal foil negative electrode may not be performed well, and if the discharge current is too small, the process time may be prolonged and process efficiency may be reduced.

Before forming the half-cell, the method may further include forming a metal foil electrode.

The forming of the metal foil electrode may include forming a metal foil negative electrode by rolling a metal.

Accordingly, the metal foil electrode can be formed in a simple manner, and the thickness, shape, and size of the electrode can be easily adjusted.

In addition, by forming an alloy active material layer on one surface of the metal foil electrode, a high-capacity negative electrode having improved cycle characteristics can be manufactured by a simple process.

19 illustrates a structure of a full-cell as an example.

The manufacturing of the full-cell may include configuring the full-cell in the structure shown in FIG. 19 .

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 described above.

The electrolyte may include a metal salt and an ether-based solvent. Specifically, the metal salt is NaPF ₆ , NaClO ₄ , NaCF ₃ SO ₃ , NaBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiBF ₄ , LiTFSI, Mg(PF ₆ ) ₂ , Mg(ClO ₄ ) ₂ , Mg(CF _{3 )} SO ₃ ) ₂ , Mg(BF ₄ ) ₂ , Mg(TFSI) ₂ , Mg(HMDS) ₂ , and MgCl ₂ may include one selected from the group consisting of.

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 (PEGDME), polyethyleneoxide (PEO), dioxolane (DOL), and mixtures thereof It may be selected from the group comprising 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 included. However, the present invention is not limited thereto, and those that can be applied as a positive electrode of a secondary battery in the related art may be included therein.

19 illustrates a structure of a full-cell as an example.

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 one 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) was 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 separating 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, preferred examples and comparative examples of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited thereto.

Example 1: Na _0.22 Negative electrode including Sn alloy active material layer

Sn metal was rolled to a thickness of 30 μm and punched to a size of 6 mm in diameter to prepare a Sn metal foil negative electrode.

As shown in FIG. 2 , the Sn metal foil was disposed on the positive electrode, and the Na metal electrode was disposed on the negative electrode, thereby preparing a half-cell. At a discharge current of 0.01 C-rate, a discharge capacity of 50 mAh/g was discharged _{to prepare a negative electrode of Example 1 in which a Na 0.22} Sn alloy active material layer was formed on a Sn current collector. The thickness of the Sn current collector of the prepared negative electrode is 23.4 μm, and the thickness of the Na _0.22 Sn alloy active material layer is 14.51 μm.

3 is a graph showing the electrochemical reaction section for preparing the negative electrode of Example 1. It can be seen that the initial flat voltage section boundary point is a point having a discharge capacity of 226 mAh/g, and in order to manufacture the negative electrode according to an embodiment of the present invention, the discharge capacity must be controlled to be less than 226 mAh/g. When discharging too much, cracks may occur in the alloy active material layer because the current collector completely changes to the active material layer as described above. Looking at the graph, it can be seen that the ratio of Na/Sn of the anode alloy active material layer according to an embodiment of the present invention is greater than 0 and less than 1.

4 is a photograph of the alloy active material layer of the negative electrode of Example 1. It can be seen that the surface of the Sn foil reacted with Na and lost its metallic luster.

5 is a photograph of the current collector of the negative electrode of Example 1. It can be confirmed that the Sn current collector on the back surface of the alloy active material layer maintains metallic luster. In addition, it can be seen that since the current collector is made of metal and the active material layer is firmly connected to the current collector, it can be bent or bent without causing separation or drop-off of the active material layer from the current collector. .

6 is a SEM photograph of the alloy active material layer of the negative electrode of Example 1. It can be seen that the surface of the alloy active material layer has a plurality of columnar structures in which alloy active material particles having an average diameter of 0.25 to 0.5 μm are stacked and bonded up and down. The porosity of the alloy active material layer was 81% by volume.

7 is an EDS spectrum of the alloy active material layer of the negative electrode of Example 1.

Table 3 below is an analysis of the content of the alloy active material layer of the negative electrode of Example 1. C is the solvent of the electrolyte, F is derived from the solute of the electrolyte, O is oxidation and Cu is represented by the holder of the SEM, and cannot be considered as a component included in the anode alloy active material layer. It can be seen that the content of Na and Sn in the negative electrode alloy active material layer of Example 1 of the present application is 99% by weight or more based on 100% by weight of the total negative electrode, except for the components unavoidably included in the component measurement. Preferably, there is no impurities at all, and the content of Na and Sn in the negative electrode can be understood to be 100% by weight.

ingredient content (wt%) C 4.8 O 10.15 F 2.31 Na 5.37 Cu 1.64 Sn 75.73 Sum 100

8 is a graph showing the cycle characteristics of the negative electrode of Example 1 at a current density of 0.01 C. It shows a very stable capacity of 50 mAh/g for 100 cycles. In particular, the retention rate of 100-cycle discharge capacity compared to 1-cycle discharge capacity is 99% or more, which is close to 100%, and the difference between 1-cycle discharge capacity and 2-cycle discharge capacity is also less than 1%, which is almost 0%. can be found close. The current collector and the active material layer were initially bonded to atoms in the same material, and even if a new phase is formed by absorbing ions into the lattice of the active material layer, the interatomic bond between the active material layer and the current collector is maintained. The reduction may be almost non-existent.

9 shows a charge/discharge curve at a current density of 0.01 C of the negative electrode of Example 1. After 10 cycles, the reversible capacity was stabilized at 50 mAh/g, and the charging voltage flat section changes to one section during 100 cycles. One finally completed flat section may make it easier to control the battery voltage. As the cycle progresses, it can be seen that the overvoltage decreases because the voltage of the discharge curve increases. In other words, it means that the influence of internal resistance on expansion has almost disappeared. The expansion and contraction of the active material layer may be smoothly performed during the charging/discharging process.

Example 2: Anode comprising NaBi alloy active material layer

Bi metal was rolled to a thickness of 2 mm and punched to a size of 4 mm x 4 mm to prepare a Bi metal foil negative electrode.

As shown in FIG. 2 , the Bi metal foil was disposed on the positive electrode and the Na metal electrode was disposed on the negative electrode, thereby preparing a half-cell. At a discharge current of 0.01 C-rate, a discharge capacity of 128 mAh/g was discharged to prepare a negative electrode of Example 2 in which a NaBi alloy active material layer was formed on a Bi current collector. The thickness of the Bi current collector of the prepared negative electrode was 0.02 mm, and the thickness of the NaBi alloy active material layer was 3 mm. The ratio of the alloy active material layer thickness/the current collector thickness is 150.

10 is a photograph of the alloy active material layer of the negative electrode of Example 2; It can be seen that the surface loses its metallic luster by reacting with Na.

11 is a photograph of the current collector of the negative electrode of Example 2. It can be seen that the surface retains the Bi metallic luster.

12 is a charge/discharge curve at 0.01 C of the negative electrode of Example 2. It shows a very reversible capacity of 127 mAh/g during the charging and discharging process.

13 is a discharge graph of a Bi electrode in which an electrochemical reaction section (initial flat voltage section) for manufacturing a Bi electrode corresponding to Example 2 is indicated by a red region. According to the discharge graph, the point at which the discharge capacity becomes 128 mAh/g is the boundary point of the first flat voltage section of the Bi electrode.

14 is a graph showing cycle characteristics of the Bi cathode of Example 2 1 to 30 times. It can be seen that the retention of the 30 cycle discharge capacity compared to the 1 cycle discharge capacity is 93.4%, which is very high, and the difference between the 1 cycle discharge capacity and the 2 cycle discharge capacity is also very small at 0.5%.

Evaluation Example 1 - Electrode shape evaluation after charge/discharge cycle

15 is an actual photograph of the electrode of Example 1 ( _{a negative electrode including a Na 0.22} Sn alloy active material layer) after performing one charge/discharge cycle.

Figure 16 (a) shows an actual photograph of the electrode of Comparative Example 1, and Figure 16 (b) is an actual photograph of the electrode after performing one charge/discharge cycle of the electrode of Comparative Example under the same conditions as in Example 1. will be. Specifically, the electrode of Comparative Example 1 was charged and discharged once after completely discharging the _{Sn metal foil to Na 15} Sn _{4 .}

The electrode of Example 1 of FIG. 15 and the electrode of Comparative Example 1 of FIG. 16 differed only in electrodes, and all other experimental conditions were controlled the same, and the experiment was performed.

In the case of the electrode of Example 1, it can be confirmed that the electrode active material layer is stably maintained without being separated from the current collector.

On the other hand, in the case of the electrode of Comparative Example 1, it can be seen that the electrode active material layer is broken due to volume expansion and contraction of the electrode active material and the electrode active material after performing one charge/discharge cycle, so that the electrical connection is completely cut off.

In the case of the electrode of Example 1, the current collector and the active material layer were initially atomicly bonded in the same material, and even if the active material layer is formed on the current collector by partially alloying the current collector, interatomic bonding between the active material layer and the current collector Since it maintains, the bond between the current collector and the active material layer may be strong. As a result, it can be seen that it can contribute to the improvement of the charge/discharge cycle characteristics.

Evaluation Example 2 - Evaluation of adhesion between the current collector and the alloy active material layer

17 shows an actual photograph of the electrode of Comparative Example 2 after removal of the separator.

Specifically, a powder of 70 wt% Sn powder, 20 wt% of MWCNT (multi walled carbon nanotube) conductive material, and 10 wt% of PVdF binder was mixed with a methylpyrrolidone (N-Methyl-2-pyrrolidone, NMP) solvent. A slurry was prepared by milling. This was applied to Cu foil and dried to prepare a tin electrode of Comparative Example 2.

Sodium/Separator+Electrolyte/Comparative Example 2 A battery of Comparative Example 2 was constructed by stacking the tin electrodes in the order, and after performing one charge/discharge cycle, a photograph of the battery and the electrode from which the separator was removed is shown in FIG. 16 .

Referring to FIG. 17 , when the separator is removed, it can be seen that the electrode active material layer is separated from the Cu foil to expose the copper current collector.

15 is a photograph of the battery and the electrode from which the separator was removed after performing one charge/discharge cycle by preparing a battery in the same manner as in Comparative Group 1 except that the electrode of Example 1 was used instead of the tin electrode of Comparative Example 2;

Even after removing the separator, it can be seen that the electrode active material layer is not separated from the current collector and maintains the shape of the electrode active material layer.

That is, it can be seen that the negative electrode of Example 1 has stronger and stronger adhesion between the current collector and the active material layer than the electrode of Comparative Example 2. This is that the negative electrode manufactured according to an embodiment of the present invention is manufactured by forming an alloy active material layer on one surface of the first metal foil, and since the adhesive force between the current collector and the alloy active material layer is strong, the active material layer is separated from the current collector can be suppressed, the cycle characteristics are excellent, and it can contribute to the improvement of the contact characteristics at the interface.

The present invention is not limited to the above embodiments, but can be manufactured in a variety of 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 (18)

a current collector including a first metal; and
Including; an alloy active material layer comprising an alloy of the first metal and the second metal;
The first metal included in the current collector and the alloy active material layer is the same metal,
The first metal is selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi,
The second metal is selected from the group consisting of Na, Li, and Mg,
The current collector and the alloy active material layer have an atomic bond connecting the current collector and the alloy active material layer,
The alloy active material layer has a plurality of columnar structures in which micro metal particles are stacked and bonded up and down,
The alloy active material layer will include an alloy represented by any one of the following formulas 1 to 24, the negative electrode.
[Formula 1]
Na _a Ga
(0 < a < 1/4 in Formula 1)
[Formula 2]
Na _b Ge
(0 < b < 1 in Formula 2)
[Formula 3]
Na _c In
(0 < c < 5/8 in Formula 3)
[Formula 4]
Na _d Sn
(0 < d < 1 in Formula 4)
[Formula 5]
Na _e Sb
(0 < e < 1 in Formula 5)
[Formula 6]
Na _f Tl
(0 < f < 1/2 in Formula 6)
[Formula 7]
Na _g Pb
(0 < g < 1 in Formula 7)
[Formula 8]
Na _h Bi
(0 < h < 1 in Formula 8)
[Formula 9]
Li _i Ga
(0 < i < 1/2 in Formula 9)
[Formula 10]
Li _j Ge
(0 < j < 3 in Formula 10)
[Formula 11]
Li _k In
(0 < k < 2 in Formula 11)
[Formula 12]
Li _l Sn
(0 < l < 1 in Formula 12)
[Formula 13]
Li _m Sb
(0 < m < 2 in Formula 13)
[Formula 14]
Li _n Tl
(0 < n < 1 in Formula 14)
[Formula 15]
Li _o Pb
(0 < o < 1 in Formula 15)
[Formula 16]
Li _p Bi
(0 < p < 1 in Formula 16)
[Formula 17]
Mg _q Ga
(0 < q < 1/2 in Formula 17)
[Formula 18]
Mg _r Ge
(0 < r < 2 in Formula 18)
[Formula 19]
Mg _s In
(0 < s < 1/2 in Formula 19)
[Formula 20]
Mg _t Sn
(0 < t < 2 in Formula 20)
[Formula 21]
Mg _u Sb
(0 < u < 3/2 in Formula 21)
[Formula 22]
Mg _v Tl
(0 < v < 1 in Formula 22)
[Formula 23]
Mg _w Pb
(0 < w < 2 in Formula 23)
[Formula 24]
Mg _y Bi
(0 < y < 3/2 in Formula 24)
delete According to claim 1,
The alloy active material layer will include 97 mass% or more of the alloy represented by any one of Formulas 1 to 24 based on 100 mass% of the alloy active material layer,
cathode.
delete According to claim 1,
The micro metal particles have an average diameter of 0.1 to 5 μm,
cathode.
According to claim 1,
The alloy active material layer has a porosity of 50 to 90% by volume,
cathode.
According to claim 1,
The thickness of the alloy active material layer relative to the current collector thickness (alloy active material layer thickness / current collector thickness) is 0.01 to 200,
cathode.
According to claim 1,
When discharging at a current density of 0.01 C in the half cell, the retention rate of 100 cycle discharge capacity is 95% or more compared to 1 cycle discharge capacity,
cathode.
According to claim 1,
When discharging at a current density of 0.01 C in the half cell, the retention rate of 30 cycle discharge capacity is 92% or more compared to 1 cycle discharge capacity,
cathode.
According to claim 1,
When discharging at a current density of 0.01 C in a half cell, the difference between the discharge capacity of 1 cycle and the discharge capacity of 2 cycles is 5% or less,
cathode.
constructing a half-cell including a metal foil negative electrode including a first metal and a metal electrode including a second metal;
discharging the half-cell to less than a discharge capacity of a boundary point of an initial flat voltage section on a discharge graph to form an alloy active material layer on one surface of the metal foil negative electrode; and
Manufacturing a full-cell (full-cell) including a negative electrode having an alloy active material layer formed on the one surface, a positive electrode including a positive electrode active material, and an electrolyte;
The first metal is selected from the group consisting of Ga, Ge, In, Sn, Sb, Tl, Pb, and Bi,
The second metal is selected from the group consisting of Na, Li, and Mg,
The alloy active material layer includes an alloy of a first metal and a second metal,
The negative electrode on which the alloy active material layer is formed has an atomic bond connecting the current collector and the alloy active material layer to the current collector and the alloy active material layer,
The alloy active material layer will have a plurality of columnar structures in which micro metal particles are stacked and bonded up and down
A method for manufacturing a secondary battery.
12. The method of claim 11,
In the step of forming the alloy active material layer
Controlling the discharge capacity to less than 1107 mAh / g,
A method for manufacturing a secondary battery.
delete 12. The method of claim 11,
In the step of forming the alloy active material layer
When the alkali metal is Li,
The metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 226 mAh/g;
The metal foil is a Bi metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 128 mAh/g;
The metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 192 mAh/g;
The metal foil is a Ge metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 1623 mAh/g;
The metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 700 mAh/g,
The metal foil is an Sb metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 660mAh/g;
The metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 525 mAh/g, or
The metal foil is a Pb metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 569 mAh/g,
When the alkali metal is Na,
The metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 226 mAh/g;
The metal foil is a Bi metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 128 mAh/g;
The metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 96 mAh/g,
The metal foil is a Ge metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 369 mAh/g, or
The metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 145 mAh/g;
The metal foil is an Sb metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 220 mAh/g;
The metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 65 mAh/g;
The metal foil is a Pb metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 129 mAh/g,
When the alkali metal is Mg,
The metal foil negative electrode is a Sn metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 452 mAh/g, or
The metal foil is a Bi metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 192 mAh/g;
The metal foil is a Ga metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 192 mAh/g;
The metal foil is a Ge metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 738 mAh/g;
The metal foil is an In metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 116 mAh/g;
The metal foil is an Sb metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 330mAh/g;
The metal foil is a Tl metal foil negative electrode, and the discharge capacity is controlled to be greater than 0, and less than 131 mAh/g;
The metal foil is a Pb metal foil negative electrode, and the discharge capacity is controlled to more than 0, and less than 259 mAh / g,
A method for manufacturing a secondary battery.
12. The method of claim 11,
Prior to the step of configuring the half-cell,
rolling the metal to form a metal foil negative electrode,
A method for manufacturing a secondary battery.
anode;
electrolyte; and
Claims 1, 3, and that comprising the negative electrode of any one of claims 5 to 10,
secondary battery.
17. The method of claim 16,
The electrolyte will include a metal salt, and an ether-based solvent.
secondary battery.
18. The method of claim 17,
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), polyethyleneoxide (PEO), dioxolane (DOL) and these Which is selected from the group comprising a mixture of
secondary battery.

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