KR20060098137A - Self-healing gallium alloy electrode, lithium secondary battery using thereof and manufacturing method of gallium alloy electrode - Google Patents

Abstract

The present invention relates to a self-recoverable gallium alloy electrode, a lithium secondary battery and a gallium alloy electrode manufacturing method using the same. In the present invention, spontaneous alloying properties of Ga and fluidity properties of Ga liquid are used to prevent the electrode from cracking or crushing or detaching the electrode active material even during repeated charging and discharging processes in a lithium secondary battery. In addition, the production of the electrode plate by applying only the Ga alloy directly to the current collector without the addition of a conductive material and a binder to increase the capacity of the electrode plate and significantly improve the energy density of the lithium secondary battery. The present invention provides a self-recoverable gallium alloy electrode comprising a gallium alloy, characterized in that the gallium alloy and the current collector is alloyed or the flowability of the gallium alloy above the melting point of the gallium alloy and a lithium secondary battery using the same. do. In addition, the present invention is due to the coating step of applying a gallium alloy to the current collector, the alloying step of the gallium alloy and the current collector or the temperature control step for the liquid fluidization of the gallium alloy above the melting point of the gallium alloy It provides a gallium alloy electrode manufacturing method characterized in that the self-recovery.

Gallium, Alloy, Self-Recovery, Lithium Secondary Battery, High Power Battery, Liquid

Description

Self-recoverable gallium alloy electrode, method for manufacturing lithium secondary battery and gallium alloy electrode using same {SELF-HEALING GALLIUM ALLOY ELECTRODE, LITHIUM SECONDARY BATTERY USING THEREOF AND MANUFACTURING METHOD OF GALLIUM ALLOY ELECTRODE}

1 is a one-time charge and discharge graph of the electrode prepared in Example 1,

2 is a one-time charge and discharge graph of the electrode prepared in Example 2,

3 is a one-time charge and discharge graph of the electrode prepared in Example 3,

4 is a one-time charge and discharge graph of the electrode prepared in Example 4,

5 is a one-time charge and discharge graph of the electrode prepared in Example 5,

6 is a charge and discharge reversibility graph of the electrode prepared in Example 1,

7 is a charge and discharge reversibility graph of the electrode prepared in Example 2,

8 is a charge and discharge reversibility graph of the electrode prepared in Example 5,

9 is a graph showing charge and discharge output characteristics of the electrode manufactured in Example 1. FIG.

The present invention relates to a self-recoverable gallium alloy electrode, a lithium secondary battery and a gallium alloy electrode manufacturing method using the same. More specifically, self-healing by reducing the deterioration phenomenon by using a metal capable of alloy reaction with Ga alloy at high speed as a current collector, or by using Ga as an electrode active material at a temperature above the melting point of the Ga alloy (Self-Healing) The present invention relates to a gallium alloy electrode, a lithium secondary battery and a gallium alloy electrode manufacturing method using the same.

At present, a representative anode material of a lithium secondary battery is a carbon material, which is divided into crystalline graphite and amorphous carbon according to the degree of crystallinity. Graphite materials are also subdivided into natural graphite and artificial graphite, and amorphous carbon is further classified into non-graphitizable carbons and graphitizable carbons. Among them, g-MCMB (Graphitized Meso Carbon Microbeads), a kind of artificial graphite, is the most preferred product as a negative electrode material for secondary batteries. The reason is that the particles are spherical in shape and have advantages such as high packing density of spherical carbon and excellent workability of plate forming. However, graphite carbon, such as g-MCMB, has a theoretical capacity of only 372 mAh / g, which limits the application of a lithium secondary battery having a high capacity or a high energy density as a negative electrode active material.

Metals such as Sn and semiconductors such as Si and metal oxides such as SnO ₂ have been proposed as new anode alloy materials for high capacity lithium secondary batteries. These materials have a high theoretical capacity in the range of 700 mAh / g to 3500 mAh / g, but in the course of charging and discharging, the electrode may crack due to several hundred percent volume change, or the active material of the electrode may be crushed or detached from the electrode, thereby causing the electrode to break. There is a serious problem with reversibility because it deteriorates. Another disadvantage of metal oxides is their large irreversible capacity.

In the case of Ga metal among the alloy materials used as the negative electrode material of the lithium secondary battery, a solid LiGaIn alloy was applied to the negative electrode of the lithium secondary battery (US Patent Number: 4,808,499), and the solid LiGa alloy was a lithium secondary battery negative electrode. There have been reports of their potential as substances (p189-197, vol. 176, 2005, Solid State Ionics). However, the above two studies used Ga in powder form to produce a solid alloy containing Li to use Ga as a negative electrode of a lithium secondary battery. No attempt was made to use metals where alloying takes place.

In addition, in the above study, in order to prepare an active material in a powder state as an electrode, mixing a conductive material and a binder together with a conductive material and a binder, as in preparing an electrode plate of carbon, alloy, and metal oxide materials, adding an organic solvent to the mixture to prepare a slurry. And applying the slurry to a current collector and drying and rolling the current collector to which the slurry is applied.

The composite electrode includes a binder such as polyvinyllidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and the like, which are insulators. Since the binder is a polymer of the insulator, the resistance of the electrode is increased, and when the resistance of the electrode is increased, the performance of the battery is reduced. As a result, the electrical conductivity of the electrode plate is low, and the diffusion of lithium ions into the active material in the solid state is slow, so the output characteristics are limited. In addition, the conductive material and the binder is added, there is a problem that the capacity per unit weight or unit volume is small.

In general, the reaction rate of the lithium secondary battery is determined according to whether or not Li ions diffuse well in the active material. Therefore, in order to use a high current, the diffusion path of Li ions must be reduced or minimized. To this end, a method of reducing the particle size of an existing active material is attempted. It is difficult to manufacture, and there are disadvantages in that it costs a lot to produce fine active material particles.

In order to overcome the above problems of the prior art, the self-recoverable gallium alloy electrode according to the present invention, a lithium secondary battery and a gallium alloy electrode manufacturing method using the same in the lithium secondary battery using the spontaneous alloying properties of Ga or the fluidity characteristics of Ga liquid It is an object of the present invention to prevent an electrode from cracking or crushing or detaching an electrode active material even in repeated charging and discharging processes in a battery. In addition, in the gallium alloy electrode according to the present invention, a lithium secondary battery and a gallium alloy manufacturing method using the same, the electrode plate is manufactured by applying only a Ga alloy directly to a current collector without adding a conductive material and a binder, thereby increasing the capacity of the electrode plate. And to significantly improve the energy density of lithium secondary batteries.

In order to achieve the above object, the present invention includes a gallium alloy, and self-recoverable gallium alloy electrode, characterized in that the gallium alloy and the current collector or the gallium alloy using the liquid fluidity above the melting point of the gallium alloy; It provides a lithium secondary battery using the same. In addition, the present invention includes a coating step of applying a gallium alloy to the current collector, an alloying step of the gallium alloy and the current collector or a temperature control step for using the liquid flow of the gallium alloy above the melting point of the gallium alloy. It provides a gallium alloy electrode manufacturing method characterized in that the self-recovery.

Hereinafter, the present invention will be described in detail based on the drawings and preferred embodiments of the present invention.

Terms used in the present specification are defined as follows.

As used herein, the term “gallium alloy” refers to an alloy made of gallium and one or more other metals, and includes gallium which does not form an alloy.

In the present specification, 'self-recovery' refers to a phenomenon such as cracking, pulverization, and detachment of the electrode, which occurs when gallium reacts with Li ions during charge to cause phase transition to undergo volume expansion and contraction during reverse reaction, and the gallium alloy during discharge. This refers to preventing detachment due to cracking of the electrode through the alloying step of the current collector, or the flow of the liquid gallium alloy that changes as the gallium is completely discharged when the operating temperature is higher than the melting point of the gallium alloy.

The present invention relates to a self-recoverable gallium alloy electrode, a lithium secondary battery and a gallium alloy electrode manufacturing method using the same.

In general, the melting point of metals ranges from several hundred degrees Celsius to thousands of degrees Celsius, while the melting point of Ga is very low, 30 degrees Celsius. If the operating temperature of the lithium secondary battery according to the present invention is maintained at 30 ℃ or more, the Ga electrode is present in the liquid state. In addition, Ga is very reactive and alloys with other metals even at normal temperature and pressure. These physical and chemical properties of Ga can be used to improve or prevent performance degradation due to electrode deformation during charging and discharging through the self-healing ability of the electrode to recover itself to its original state after charging and discharging.

In the present invention, the Ga alloy electrode used as an electrode for spontaneous alloying is composed of an alloy containing at least one metal in which spontaneous alloy reaction occurs with Ga. In general, in the Ga alloy electrode according to the present invention, it is preferable that one or two metals are alloyed in addition to Ga. However, the Ga alloy may be an alloy of 3 or more in addition to Ga, as well as a composite metal electrode with a non-alloyed metal. When using a liquid electrode, alloying with one or two metals besides Ga is possible, regardless of spontaneous alloying with Ga, which depends on the operating temperature. Also possible is a composite metal electrode of a liquid gallium alloy + solid metal with a solid metal that is not alloyed. The composition of the Ga alloy is represented by the following formula. The chemical formula of the Ga alloy represents a Ga alloy having up to four metals forming an alloy with Ga, but the number of metals forming an alloy by combining with Ga in the present invention is not limited thereto.

Formula

Ga _v K _w L _x M _y N _z

(K, L, M or N is one of Cu, Sn, In, Al, Ni, Zn, Si, Mg, Ag, Mn, Fe, Mo, Ti, V, Ge, Sb, 0 <v≤1, 0≤w≤1, 0≤x≤1, 0≤y≤1, 0≤z≤1.)

In the present invention, the self-recovery capability of the Ga alloy electrode is 1) an alloying step in which Ga and other metals are self-recovered by rapidly alloying Ga and other metals during the discharge process, or 2) the Ga alloy is self-recoverable through the liquid fluidity of the Ga electrode after discharge. It is achieved through a temperature control step of temperature control above the melting point of the electrode. Look below.

1) Self-Healing Alloying Step by Ga and Metal Alloying at High Speed

When charging and discharging are performed using Ga _GaV M _w of Ga and metal M, the following reaction occurs. This alloying reaction is possible even above or below the melting point of the Ga alloy.

(a) Ga _v M _w (s) + Li ⁺ + e ⇒ LiGa _v (s) + w M (s): charging

(b) LiGa _v (s) ⇒ Li ⁺ + e + v Ga (s, l): discharge

(c) v Ga (s, l) + w M (s) ⇒ Ga _v M _w (s): spontaneous alloying reaction between Ga and current collector

The above formula represents a spontaneous alloying reaction between Ga and metal M, and two or more metals in which the alloying reaction with Ga occurs. In the present invention, after the charge and discharge, Ga, an active material, spontaneously reacts with the current collector to restore the initial electrode state. This prevents the active material from being pulverized and separated from the current collector. In other words, due to the volume change generated during the charging and discharging cycles in an alloy material such as Sn and Si, the active material is cracked, separated, and detached from the current collector, thereby overcoming the problem of deterioration of the electrode.

Hereinafter, by selecting Cu as a specific example of the M metal, it looks at the spontaneous alloying reaction of Ga and Cu.

First, in order to manufacture a Ga alloy electrode, liquid Ga is applied to a metal current collector. It is preferable that the thickness of Ga to be apply | coated is 0.1 micrometer-50 micrometers, and it is more preferable that a coating thickness is thick. The thicker the coating thickness of Ga, the smaller the amount of current collector is, and the higher the energy density. In the present invention, the thickness of the Ga ₂ Cu alloy is proportional to the amount of Ga applied on the Cu foil. Therefore, the thickness of the alloy produced by adjusting the amount and thickness of the coated Ga can also be adjusted.

When Cu foil is used as a current collector, when Ga is coated on Cu foil, spontaneous alloying of the reaction of 2Ga (l) + Cu (s) → Ga ₂ Cu (s) occurs. In other words, applying a predetermined thickness of liquid Ga on the Cu foil to form a Ga ₂ Cu alloy on the copper surface, this reaction can be accelerated through heat treatment. At this time, since only the upper part of the Ga-coated Cu foil participates in the reaction with Ga, the lower part of the copper foil is used as a current collector as pure Cu. When the Ga ₂ Cu alloy thus formed is used as a negative electrode of a lithium secondary battery, the following process is performed according to charging and discharging.

(a ') Ga ₂ Cu (s) + 2Li ⁺ + 2 ⇒ 2LiGa (s) + Cu (s): charging

(b ') 2LiGa (s) ⇒ x Li ⁺ + x e + (2-x) LiGa (s) + x Ga (s, l): discharge

(b ") x Ga (s, l) + Cu (s) ⇒ g Ga ₄ Cu ₉ (s): spontaneous alloying

(c ') (2-x) LiGa (s) ⇒ zLi ⁺ + ze + y Li ₃ Ga ₁₄ (s): discharge

(d ') y Li ₃ Ga ₁₄ (s) ⇒ (2-xy) Li ⁺ + (2-xy) e + h Ga (s, l): discharge

(d ") h Ga (s, l) + Ga ₅ Cu ₉ (s) ⇒ Ga ₂ Cu: spontaneous alloying

That is, in the (a ') reaction during charging, Li ions enter the Ga ₂ Cu (s) electrode to form 2LiGa (s) + Cu (s), thereby expanding the volume and discharging (b'), ( In the c ') and (d') reactions, the volume shrinks and cracks may occur in the electrode. However, the (b ") and (d") reactions restore the original Ga ₂ Cu electrode, resulting in continuous volume change. Metal fatigue can be reduced.

In other words, the conventional alloy composite electrode is cracked, pulverized, desorption of the electrode due to the volume change of the electrode which is continuous before charging and discharging, thereby reducing the reversibility of the electrode. However, the Ga ₂ Cu electrode can be restored to the state before the electrode is charged and discharged through spontaneous alloying reactions such as (b ″) and (d ″), which prevents fatigue accumulation even if the electrode has a volume change. Since it reduces, the deformation | transformation of an electrode can be suppressed large. This may improve the life of the battery.

The same applies to the GaSn alloy. When the GaSn eutectic alloy in a liquid state at 30 ° C. is applied onto Cu foil, Ga ₂ Cu alloy is formed and Sn is precipitated because Ga is more reactive with Cu than Sn. That is, 0.5Ga ₂ Cu (s) + Sn (s) composite electrode can be manufactured using this method.

On the other hand, the Ga ₂ Cu (s) alloy expresses the negative electrode characteristics through the charging and discharging and spontaneous alloying reactions such as the (a) to (d ") reaction, and the precipitated Sn can also react with lithium. The theoretical capacity of Sn is 994 mAh / g The reaction formula of Sn and lithium is as follows.

22Li ⁺ + 22e + 5Sn ⇔ Li ₂₂ Sn ₅

The gallium alloy electrode according to the present invention can be applied to a lithium secondary battery operated at a temperature at which Ga is spontaneously alloyed with another metal. The field of application is various for automobiles, motorcycles, portable terminals, portable electric appliances, and the like.

By the same principle, Ga _v M _w N _x (M or N is one of Cu, Sn, In, Al, Ni, Zn, Si, Mg, Ag, Mn, Fe, Mo, Ti, V, Ge, Sb, An alloy having a composition of 0 <v ≤ 1, 0 ≤ w ≤ 1, and 0 ≤ x ≤ 1) may also be coated on Cu foil to prepare an electrode. In order for the Ga _v M _w N _x alloy to be coated on Cu foil so that an alloying reaction of Ga occurs, Ga is more reactive with Cu than M or N metal. Ga ₂ Cu alloy is formed and M or N metal is precipitated.

2) Temperature control step to maintain the temperature above the melting point of the Ga alloy to self-healing through the liquid flow of the Ga electrode

When Ga satisfies the temperature condition that can exist in the liquid state, the liquid Ga is charged and discharged as follows.

(e) Ga (l) + 2Li ⁺ + e ⇒ Li ₂ Ga (s): charging

(f) Li ₂ Ga (s) ⇒ 2Li ⁺ + e + Ga (l): discharge

That is, in the charging step, liquid Ga reacts with Li ions to cause a phase transition, and Li ₂ Ga (s) made of the phase transition is restored to liquid Ga (l) upon discharge. Phenomena such as cracking, crushing, and detachment, which occur when the phase changes from a liquid state to a solid state, can be overcome by using the fluidity of the liquid through the reactions (e) and (f).

Let's take a closer look at Ga's self-healing process.

First, in order to manufacture a Ga alloy electrode, liquid Ga is applied to a current collector having excellent conductivity. Liquid Ga is used for easy electrode fabrication and can be heated for this purpose. For example, when Mo foil is used as a current collector, if Ga is applied on Mo foil and then maintained at 30 ° C. or higher, it is possible to manufacture a liquid electrode in which the active material Ga is in a liquid state. However, since Mo is not alloyed with Ga at room temperature and normal pressure, the Mo can be stored in a liquid state.

During charging, the Ga phase in the liquid phase is phase-transferred in the order of Li ₃ Ga ₁₄ (s) ⇒ LiGa (s) ⇒ Li ₂ Ga (s) by alloying with Li, thereby expanding the volume. The theoretical capacity of Li ₂ Ga is 769 mAh / g. When discharging, the reaction proceeds in the reverse order and the volume shrinks. At this time, a crack, pulverization, or detachment of a solid-state alloy of Li and Ga (Li ₃ Ga ₁₄ , LiGa or Li ₂ Ga) may occur. have. However, after the complete discharge, Ga is converted into a liquid state, so that the electrode, which has been cracked through the fluidity of the liquid, aggregates again. The self-healing ability of the present invention reduces the deterioration due to cracking, crushing, and detachment, so that the electrode is excellent in reversibility and greatly extends its lifespan.

In addition to pure Ga, the eutectic alloy of Ga has a low melting point. For example, as a two-component eutectic alloy, GaIn (Ga: In = 75.5 wt%: 24.5 wt%) has a melting point of 17 ° C., and GaSn (Ga: Sn = 92 wt%: 8 wt%) has 25 ° C. . As a three-component eutectic alloy, GaInSn (Ga: In: Sn = 62 wt%: 22 wt%: 16 wt%) has a melting point of 11 ° C. Thus they can also be used as liquid electrode materials and the reversibility is improved.

Even when the two- or three-component alloys have different component ratios from eutectic alloys, they can be used as liquid electrode materials by adjusting the operating temperature above the alloy's melting point. In addition, alloys with different composition ratios from eutectic alloys are in the liquid state during charging and discharging because they exist as a mixture of eutectic alloys and solid metals at the operating temperature between the melting point of the eutectic alloy and the metal melting point and thus are reversible. And high output characteristics are improved.

In the present invention, a temperature control device is provided to maintain the temperature condition above the melting point of the gallium alloy. If the room temperature is above the melting point of the gallium alloy, the thermostat becomes the room environment itself. It is preferable to use a well-known thing for a thermostat.

In the lithium secondary battery including the Ga alloy electrode according to the present invention, since there is no binder and a conductive material, which are non-conductors used in general composite electrodes, excellent electrical conductivity and small electrode resistance have high output characteristics. In addition, the electrode density is improved, and the energy density of the electrode can be improved.

A Ga alloy electrode according to the present invention is used as a cathode, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _4, etc. are used as an anode, and a separator is inserted therebetween.

The membrane blocks the internal short circuit of the two electrodes and impregnates the electrolyte, and materials that may be used include polymer, glass fiber mat, and kraft paper.  2400, 2300 (manufactured by Hoechest Celanese Corp), polypropylene membrane (manufactured by Ube Industries Ltd or Pall RAI). The electrolyte is a system in which lithium salt is dissolved in an organic solvent. Lithium salt is LiClO ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiPF ₆ , LiSCN and LiC (CF ₃ SO ₂ ) ₃ or the like may be used alone or in combination. The organic solvent may be ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, 1, 2-dimethoxyethane, 1,2-diethoxyethane, gamma-butyrolactone, tetrahydrofuran, 2-methyltetra 2-methyltetrahydrofurna, 1,3-dioxene (1,3-dioxolane), 4-methyl-1,3-dioxene (4-methyl-1,3-dioxolane), diethyl ether ), Sulfolane can be used alone or mixed with each other. In addition, a polyethylene electrolyte (PEO) -based polymer electrolyte or a solid electrolyte such as Li ₃ PO ₄ -Li ₂ S-SiS ₂ may be used.

The gallium alloy electrode manufacturing method according to the present invention is a coating step of applying a gallium alloy to the current collector, an alloying step of alloying the gallium alloy and the current collector, or a temperature control step for maintaining the gallium alloy in a liquid state Including a self recovery.

In the coating step, the thickness of the gallium alloy to be applied is preferably 0.1㎛ to 50㎛. The thicker the gallium alloy is, the more preferable it is. A thick gallium alloy reduces the relative amount of current collector, resulting in an increase in energy density.

In the coating step, the coating method is preferably coated with Ga to a predetermined thickness. The coating method generally used for electrodes is used. It is also possible to use a doctor blade or a similar method used in the battery system, it is also possible to use a sputtering method. In case of using doctor blade, the part of the device which is in contact with Ga should be made of SiO ₂ , TiO ₂ , Mo, or Ti which does not react with Ga at the operating temperature of the device.

In the alloying step, the temperature of the gallium alloy and the current collector is higher than the alloying temperature of the gallium alloy and other metals so that an alloy reaction can occur. In the case of Ga, the current contactor and the alloy are made at the melting point of Cu and Ga, 30 ° C. or higher, and in the case of the gallium eutectic alloy, the alloy of the gallium and the current collector is made at the melting point of the eutectic alloy. In the case of gallium eutectic alloy, when the current collector alloys with gallium, it is precipitated as a metal. However, the temperature to be alloyed and the operating temperature of the electrode may not match. When the electrode is operating, the reaction of the electrode occurs within the nano-sized crystal size, so that the alloying reaction occurs at a temperature lower than the actual manufacturing temperature of the electrode.

In the temperature control step, the temperature condition of the gallium alloy electrode is provided with a temperature control device to maintain the melting point of the gallium alloy or more. In the case of a liquid electrode, it is necessary to apply the liquid electrode material to the current collector and to keep it above the melting point of the electrode material so that the electrode material remains in a liquid state. The temperature control device can use a known control device. During the charging reaction, the liquid gallium is combined with Li ions to turn into Li ₂ Ga (s) to increase its volume, and during discharge, Li ₂ Ga (s) turns to liquid gallium while discharging Li ions again. That is, the gallium restored liquid in the process of liquid gallium changes to a solid phase with a volume expansion in the liquid phase, and again changes to a liquid phase with volume contraction has a liquid liquidity to prevent the electrode from cracking, grinding, desorption Can be.

Hereinafter, the present invention will be described in more detail based on the preferred embodiments.

Example 1 Ga ₂ Preparation of Cu Electrode

0.5 g of Ga, a solid at 25 ° C., was heated to 70 ° C., converted to a liquid phase, and then dispersed on Cu foil. When pressure is applied using a glass slide, liquid Ga is coated on the copper foil with a uniform thickness. It was heated in a 120 ° C. vacuum oven for 10 hours to convert to a Ga ₂ Cu alloy. An electrode having a Ga ₂ Cu alloy coated on top of the copper foil was fabricated.

Example 2 Ga ₂ Preparation of Cu + Sn Composite Electrode

A GaSn alloy was prepared by mixing 0.25 g of liquid Ga made by heating to 70 ° C. and 0.25 g of Sn powder (1: 1 mass ratio). It was heated above the melting point (25 ° C.) of GaSn (Ga: Sn = 92% by weight: 8% by weight) eutectic alloy to convert it into a mixture of liquid eutectic alloy and Sn solid metal and applied onto copper foil. When pressure is applied using a glass slide, liquid GaSn is applied to the copper foil with a uniform thickness. It was heated for 10 hours at 120 ℃ vacuum oven to prepare a Ga ₂ Cu + Sn composite electrode.

Example 3 Ga ₂ Preparation of Cu + In Composite Electrode

0.5 g of GaIn eutectic alloy (Ga: In = 75.5 wt%: 24.5 wt%) in a liquid phase at 25 ° C. was dispersed on Cu foil. When pressure is applied using a glass slide, liquid GaIn is coated on Cu foil with a uniform thickness. It was heated for 10 hours at 120 ℃ vacuum oven to prepare a Ga ₂ Cu + In composite electrode.

Example 4 Ga ₂ Preparation of Cu + In + Sn Composite Electrode

0.5 g of GaInSn eutectic alloy (Ga: In: Sn = 6 wt%: 22 wt%: 16 wt%) in a liquid phase at 25 ° C. was dispersed on Cu foil. When pressure is applied using a glass slide, liquid GaInSn is applied to Cu foil with a uniform thickness. This was heated for 10 hours in a 120 ℃ vacuum oven to prepare a Ga ₂ Cu + In + Sn composite electrode.

Example 5 Preparation of Ga Electrode

0.5 g of Ga, a solid at 25 ° C., was heated to 70 ° C. to be converted into a liquid phase, and then dispersed on Mo foil. When pressure is applied using a glass slide, liquid Ga is coated on Mo foil with a uniform thickness. At this time, Ga has no reactivity with Mo, and thus becomes an electrode coated with Ga on Mo foil.

Example 6 Reversibility of a Lithium Secondary Battery Using a Ga Alloy Electrode as a Negative Electrode

Working electrodes prepared as in Examples 1, 2, 3, 4, 5 were dried in a 120 ° C. vacuum oven for at least 10 hours. Coin cells were fabricated using Li metal foil as a counter electrode and 1 mol of LiPF ₆ / EC: DMC (volume ratio 1: 2) or 1 mol of LiBF ₄ / PC as electrolyte, and Constant current charge and discharge experiments were performed. During charging, constant current was applied to 0 V ( vs. Li / Li ⁺ ) at a current density of 100 mA / g, and up to 2 V ( vs. Li / Li ⁺ ) at a current density of 100 mA / g . It was. A 5 minute pause was given between charge and discharge.

Example 7 High Power Characteristics of a Lithium Secondary Battery Using a Ga Alloy Electrode as a Negative Electrode

The electrode prepared in Example 1 was dried in a 120 ° C. vacuum oven for at least 10 hours. Coin cells were prepared in the same manner as in Example 6, and constant current experiments were performed at 55 ° C. under the following conditions. During charging, a constant current was applied to 0 V ( vs. Li / Li ⁺ ) at a current density of 50 mA / g, and up to 2 V ( vs. Li / Li ⁺ ) at constant current. The current density during discharge increased with increasing the number of charge and discharge cycles, and gradually increased from 50 mA / g to 50 A / g. There was also a 5 minute pause between charge and discharge.

1 to 4 are graphs of one time charge and discharge of the electrodes prepared in Examples 1 to 5, respectively. As a result of the charge and discharge, Examples 1 to 5 show 355 mAh / g, 603 mAh / g, and 260 mAh /. Initial discharge capacities of g, 358 mAh / g and 739 mAh / g were shown, respectively, and the initial coulomb efficiencies were 95.6%, 94.7%, 71.4%, 93.7% and 98.0%, respectively. 6 to 8 are charge and discharge reversibility graphs of the electrodes prepared in Examples 1, 2, and 5, respectively, and as the number of charge / discharge recovery proceeds, the reversible capacity does not decrease significantly, thus showing stable reversibility. It can be seen.

9 is a graph of the charge / discharge high power characteristics of the electrode manufactured in Example 1, when the current density is increased 500 times from 50 mA / g to 25 A / g, at 90% of the reversible capacity shown at 50 mA / g. Corresponding doses were expressed, with a dose corresponding to 58% at 50 A / g conditions increased 1000-fold. It can be seen that the high output characteristics are very excellent.

In the above, this invention was demonstrated in detail with reference to an Example centering on a structure. However, the scope of the present invention is not limited to the above embodiments but may be embodied in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the invention as claimed in the claims, any person of ordinary skill in the art is considered to be within the scope of the claims described in the present invention to the extent possible to vary.

As described above, the spontaneous alloying properties of the Ga and the fluidity of the liquid even when the electrode is deformed in the charge and discharge copper by using the self-recoverable gallium alloy electrode, the lithium secondary battery and the gallium alloy electrode manufacturing method using the same according to the present invention By using to recover the original state after the charge and discharge can be overcome the problem of deformation of the electrode due to the volume change. In addition, in the gallium alloy electrode of the present invention, gallium has a high reactivity with lithium and has high electrical conductivity as in general metals, so that only Ga alloy is directly applied to a current collector without adding a conductive material and a binder when manufacturing an electrode plate. It greatly improves and greatly improves the energy density of the lithium secondary battery.

Claims (13)

Includes gallium alloys, Self-recovering gallium alloy electrode, characterized in that the gallium alloy and the current collector is alloying reaction Includes gallium alloys, The gallium alloy electrode which is self-recoverable by the fluidity of the liquid electrode by maintaining the gallium alloy above the melting point by a temperature controller The method according to claim 1 or 2, The gallium alloy is Cu, Sn, In, Al, Ni, Zn, Si, Mg, Ag, Mn, Fe, Mo, Ti, V, Ge, Sb and self recovery, characterized in that the gallium alloys Gallium alloy electrode The method according to claim 1 or 2, The current collector is Mo, Ti, Cu, Sn, In, Al, Ni, Zn, Si, Mg, Fe, Mn, C Self-recoverable gallium alloy electrode, characterized in that the alloy of two or more The method according to claim 1 or 2, The gallium alloy electrode does not contain a conductive material or a binder, the gallium alloy is self-recoverable gallium alloy electrode, characterized in that applied to the current collector A lithium secondary battery using the gallium alloy electrode of any one of claims 1 and 2. The method of claim 6, Salts used in the electrolyte of the lithium secondary battery are LiClO ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiPF ₆ , Lithium secondary battery, characterized in that at least one of LiSCN or LiC (CF ₃ SO ₂ ) ₃ The method of claim 6, In the lithium secondary battery, ethylene carbonate (ethylene carbonate), propylene carbonate (propylene carbonate), diethyl carbonate (diethyl carbonate), dimethyl carbonate (dimethylcarbonate), 1,2-dimethoxyethane (1,2-dimethoxyethane), 1, 2-diethoxyethane, gamma-butyrolactone, tetrahydrofuran, tetrahydrofuran, 2-methyltetrahydrofurna, 1,3-dioxane At least one of 1,3-dioxolane, 4-methyl-1,3-dioxolane, 4-ethyl-1,3-dioxolane, diethyl ether, and sulfolane is used as the organic solvent. Or a lithium secondary battery using at least one of a polyethlene oxide polymer electrolyte or Li ₃ PO ₄ -Li ₂ S-SiS ₂ as a solid electrolyte Applying a gallium alloy to the current collector; Alloying the gallium alloy with the current collector; or Gallium alloy electrode manufacturing method comprising a temperature control step for maintaining the gallium alloy in a liquid state by a temperature control device The method of claim 9, The gallium alloy is a gallium alloy, characterized in that the gallium alloys with at least one of Cu, Sn, In, Al, Ni, Zn, Si, Mg, Ag, Mn, Fe, Mo, Ti, V, Ge, Sb Electrode Manufacturing Method The method of claim 9, Gallium alloy electrode manufacturing method characterized in that the thickness of the gallium alloy is applied in the coating step is 0.1㎛ to 50㎛. The method of claim 9, The current collector is a gallium alloy electrode manufacturing method, characterized in that one or two or more alloys of Mo, Ti, Cu, Sn, In, Al, Ni, Zn, Si, Mg, Fe, Mn, C The method of claim 9, The gallium alloy electrode manufacturing method characterized in that the gallium alloy is applied to the current collector, without including a conductive material or a binder in the coating step.

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