KR20160084512A - A solid-state battery and a method for manufacturing it - Google Patents

Abstract

The present invention relates to an all solid battery, and a manufacturing method thereof. More specifically, the present invention relates to an all solid battery which can easily design a negative electrode since the negative electrode can be manufactured by a wet process, and can increase energy density and output performance by increasing a surface area of a solid electrolytic layer and a reaction area inside the negative electrode, by using a metal-based material, which is a negative electrode active material, as powder not a sheet or a foil like the existing all solid battery; and a manufacturing method thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solid-

The present invention relates to a pre-solid battery and a method of manufacturing the same. More particularly, the present invention relates to a pre-solid battery and a method of manufacturing the same. More particularly, the present invention relates to a pre- And can increase the energy density and output performance by increasing the interface area between the solid electrolyte layer and the cathode and the reaction area inside the cathode, and a method for manufacturing the same.

BACKGROUND ART [0002] Today, rechargeable secondary batteries are widely used as large-capacity power storage batteries used in electric vehicles and power storage systems, and portable high-performance energy sources in portable electronic devices such as mobile phones, camcorders, and notebook computers.

The lithium ion battery as a secondary battery has a larger capacity per unit area, a lower self-discharge rate than the nickel-manganese battery or the nickel-cadmium battery, and has advantages in ease of use because there is no memory effect.

The lithium ion battery is composed of a carbon-based cathode, an electrolyte containing an organic solvent, and a lithium-oxide cathode. The lithium-ion battery uses a chemical reaction occurring in the anode and the cathode to discharge lithium ions from the anode, And proceeds to the reverse of the charging process at the time of discharging. That is, it is a representative secondary battery which can perform charging and discharging several times by using the principle that lithium ions come and going between the positive electrode and the negative electrode.

However, since the lithium ion battery uses the liquid electrolyte containing the organic solvent, there are various problems in the stability of the battery due to leakage, impact and the like due to use of the highly volatile organic solvent.

Therefore, in order to secure the safety of a lithium ion battery, research on an all-solid-state battery using a solid electrolyte instead of a liquid electrolyte has been actively conducted.

However, all solid-state batteries have limitations in terms of energy density and output performance that are incompatible with lithium-ion batteries using conventional liquid electrolytes. Therefore, improvements in various aspects such as material and structure design are needed to solve these problems.

In order to improve the performance of a solid-state battery, studies have been actively carried out to apply a metal-based material having an energy density higher than that of a conventional carbon-based material as a negative electrode material, but since it is mainly applied in the form of a sheet or a foil, The contact area with the electrolyte layer is small and the cathode utilization rate is low and only a dry process (press molding) can be performed in the manufacturing process. Therefore, there is a limit in that there is little room for improvement in performance through reduction in thickness when designing a battery cell. Therefore, all solid-state batteries using metal-based cathodes are mainly used for the test battery specification for evaluating materials.

Korean Patent Publication No. 10-2012-0129493

It is an object of the present invention to provide a pre-solid battery having improved output by maximizing a reaction area with a solid electrolyte layer while using a metal-based material as an anode active material.

It is also an object of the present invention to provide a pre-solid battery in which the utilization rate of the anode is expanded to the inside of the cathode to increase the energy density and the life stability.

 The objects of the present invention are not limited to the above-mentioned objects, and other objects of the present invention which are not mentioned can be understood by the following description and can be more clearly understood by the embodiments of the present invention. Further, the objects of the present invention can be realized by the means shown in the claims and their combinations.

In order to achieve the above object, the present invention includes the following configuration.

The pre-solid battery according to the present invention includes a cathode including a cathode active material, and a cathode and a solid electrolyte layer including a metal powder obtained by mixing lithium powder and indium powder.

A method of manufacturing a pre-solid battery according to the present invention includes the steps of preparing a positive electrode composite, preparing an electrolyte slurry, sequentially coating the positive electrode composite and an electrolyte slurry on a substrate to produce a laminated electrode, Preparing a metal powder by mixing the metal powder with a wet process, preparing a negative electrode by pressing the metal powder to a current collector, and pressing the laminate electrode and the negative electrode to manufacture a battery cell.

The present invention has the following effects by including the above configuration.

The present invention has an effect of providing an all solid battery with improved output performance by improving the resistance inside the battery cell and maximizing the interfacial area (reaction area) between the solid electrolyte layer and the cathode .

The present invention provides a pre-solid battery which can be manufactured by a wet process by pulverizing a metal-based material such as a sheet or a foil used as a conventional negative electrode active material, thereby facilitating the design of the electrode.

The present invention provides an all-solid-state battery in which the utilization ratio of the negative electrode is expanded to the inside of the negative electrode to increase the energy density and the life stability.

According to the present invention, the surface area of a negative electrode is increased by powdering a metal-based material to form a negative electrode. Accordingly, the production of dendrite can be dispersed, thereby providing an all-solid battery with improved safety.

1 is a cross-sectional view schematically showing a configuration of a pre-solid battery according to the present invention.
FIG. 2 is a graph showing the results of measurement examples in which the electrochemical performance of all the solid-state batteries according to Examples and Comparative Examples was evaluated.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be easily understood by those skilled in the art.

1, a pre-solid battery according to the present invention includes an anode 10 including a cathode active material 11, a cathode 30 including a metal powder obtained by mixing a lithium powder 31 and an indium powder 33, ) And a solid electrolyte layer (20).

The positive electrode 10 includes a positive electrode active material 11 which is a metal oxide and is configured to generate lithium ions through a chemical reaction upon charging of the entire solid electrolyte cell and preferably includes a conductive material 13, And may further include a solid electrolyte 17.

The positive electrode active material 11 contains a lithium-based positive electrode active material such as LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ , or a lithium-based positive electrode active material containing Ni, Co, Mn, Al, As the transition metal oxide, lithium can be inserted and desorbed freely electrochemically at the time of charging / discharging of the all solid battery.

The cathode active material 11 is coated with a lithium conductive oxide film (not shown) of niobium (Nb), aluminum (Al), or zirconium (Zr) to suppress surface reactivity with the solid electrolyte 17 and improve resistance Can be applied.

Since the cathode active material 11 has low electron conductivity, the conductive material 13 may be made of a conductive material such as carbon black (carbon black), ketjen black, By adding ashes, the electron conductivity in the anode can be improved.

The binder 15 binds the constituent elements of the anode and can also play the role of reducing the interfacial resistance between the constituent elements due to the volume expansion of the pre-solid battery during charging and discharging.

The binder 15 may be a powder type Super P, a rod type Denka or Vapor Growth Carbon Fiber (VGCF), but is not limited thereto, and examples thereof include fluorine type, diene type, acrylic type, Can also be used.

The solid electrolyte 17 is a carrier dedicated to the movement of lithium ions in the anode 10. The entire solid electrolyte according to the present invention has a structure in which the solid electrolyte 13 is separated from the solid electrolyte contained in the solid electrolyte layer 20, 10 and the cathode 30 may contain a predetermined amount of solid electrolyte. The solid electrolyte will be described in detail later.

The anode may be manufactured by mixing the components and coating the current collector. A detailed description will be given later.

The solid electrolyte layer 20 is interposed between the positive electrode 10 and the negative electrode 30 and is a carrier dedicated to the movement of lithium ions according to charge and discharge of the pre-solid battery. The present invention is advantageous in that a high capacity and long life secondary battery can be provided by using a sulfide-based solid electrolyte instead of a liquid electrolyte of a conventional lithium secondary battery.

The solid electrolyte layer 20 _{Li 3 N, LISICON (Lithium Super} Ionic Conductor), LIPON (Li 3 + yPO 4 -xNx), Thio-LISICON (Li 3 .25Ge0.25P0.75S 4), Li 2 S, Li ₂ SP ₂ S ₅ , Li ₂ S-SiS ₂ , Li ₂ S-GeS ₂ , Li ₂ SB ₂ S ₅ , Li ₂ S-Al ₂ S ₅ and Li ₂ O-Al ₂ O ₃ -TiO ₂ - P ₂ O ₅ (LATP), and other oxide-based or sulfide-based materials having an amorphous structure can be used.

Since the solid electrolyte layer 20 needs to transfer lithium ions between the anode 10 and the cathode 30, a material capable of achieving lithium ion conductivity of 10 ^-4 S / cm or more can be used.

Since the cathode 30 includes a metal powder in which a lithium powder 31 and an indium powder 33 are mixed as an active material, the cathode 30 has an energy density superior to that of a carbon-based anode of a conventional lithium secondary battery.

Unlike the conventional all-solid-state battery, the negative electrode 30 is formed by powdering and using a metal-based material in the form of a sheet or a foil, so that the interface area with the solid electrolyte layer 20 And the effective surface area inside the cathode 30 participating in the cell reaction is greatly increased.

The lithium powder 31 and the indium powder 33 may be mixed in a mass ratio of 5:95 to 50:50. If the lithium content in the indium exceeds 50%, the potential due to the electrochemical reaction of lithium changes to cause an unstable reaction of the lithium metal. If the lithium content in the indium is less than 5%, it is difficult to form a rhombic dislocation. And indium powder may be mixed in the above-described mass ratio.

The particle size of the metal powder may preferably be 4 to 8 mu m. In order to produce an indium-lithium alloy cathode having a uniform film shape, a slurry mixing and coating process based on a wet process is performed, and a minimum particle size range in consideration of a normal distribution of the particle size is specified. However, the present invention is not limited to the claims, and it can be applied within a range of dispersibility from several hundred nm to several tens of μm according to the powder dispersion process.

The metal powder may be mixed with the solid electrolyte as described above to secure the ion conduction path in the cathode. The metal powder and the solid electrolyte may be mixed in a mass ratio of 50:50 to 95: 5. The solid electrolyte is contained in an amount of 5% or more to ensure the connectivity between the solid electrolytes in the cathode, and the metal cathode according to the present invention contains metal powder in an amount of 50% or more, .

The negative electrode may be manufactured by mixing the metal powder and the solid electrolyte and then press-molding the same into the current collector. Details will be described later.

A method of manufacturing a pre-solid battery according to the present invention includes the steps of preparing a positive electrode composite, preparing an electrolyte slurry, sequentially coating the positive electrode composite and an electrolyte slurry on a substrate to produce a laminated electrode, Preparing a negative electrode by press-molding the mixed metal powder into a current collector, and pressing the laminate electrode and the negative electrode to manufacture a battery cell.

The positive electrode composite may be prepared by mixing the positive electrode active material, the solid electrolyte, the conductive material, and the binder at a composition ratio of 70: 30: 5: 5.

The positive electrode composite may be put into an organic solvent and mixed for a predetermined period of time to prepare a slurry in which each component is uniformly dispersed. The solids can be adjusted to a viscosity of 800 to 1200 cPs to suit the coating during the mixing process.

The organic solvent may be selected from cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, or a mixture of two or more thereof. Can be used. However, when a sulfide-based electrolyte is used, it may be preferable to use an aromatic hydrocarbon-based non-polar solvent from the viewpoint of chemical reactivity.

The electrolyte slurry is prepared by mixing a solid electrolyte and a binder at a predetermined ratio, and may be added to an organic solvent in the same manner as in the preparation of the positive electrode composite.

The laminated electrode may be manufactured by sequentially coating the positive electrode composite and the electrolyte slurry on a current collector having a predetermined thickness.

The anode composite and the electrolyte slurry may be coated on the collector by a coating method such as a roll-to-roll process, a printing process, or a gravure coating process.

The metal powder is prepared by adding indium and lithium into an electric furnace together with an inorganic solvent such as silicone oil and then heating the emulsion at 200 ° C which is higher than the melting point of indom and lithium and then drying the emulsion. can do.

The metal powder may be mixed with the solid electrolyte at a predetermined mass ratio as described above. At this time, it is preferable to mix them sufficiently for 12 hours or more by dry mixing.

The method of manufacturing the all-solid-state cell according to the present invention uses the metal-based material powdered with the negative electrode active material, so that the negative electrode can be manufactured by the wet process unlike the prior art, so that the thickness of the negative electrode can be easily controlled, And the management and control of the manufacturing environment is simple.

The negative electrode may be prepared by placing a mixture of the metal powder and the solid electrolyte on a current collector, placing the mixture in a mold, and pressing the mixture.

The battery cell can be manufactured by stacking the stacked electrode and the negative electrode, and then densifying the battery cell through a hot-high-pressure hot pressing process.

Example

An actual battery cell was fabricated by the above-described method for manufacturing all-solid-state cells. The details are as follows.

1) Preparation of solid electrolyte

The solid electrolyte included in the entire solid battery of the present invention was prepared as follows.

The amorphous sulphide solid electrolytes Li ₂ S and P ₂ S ₅ starting powders were mixed at a mass ratio of 75:25 and then prepared by high energy milling. At this time, the process was carried out in a glove box in a nitrogen atmosphere in order to prevent contact with air.

2) Preparation of anode composite

LiCoO ₂ as a cathode active material, a solid electrolyte obtained by the above method, carbon black as a conductive material, and a binder were mixed in a composition ratio of 70: 30: 5: 5 to prepare a positive electrode composite.

3) Preparation of electrolyte slurry

The solid electrolyte and the binder were mixed in a mass ratio of 95: 5 to prepare an electrolyte slurry.

4) Fabrication of laminated electrode

The positive electrode composite and the electrolyte slurry were sequentially coated on an aluminum foil (current collector) having a thickness of 15 탆 by using a doctor blade coating method to produce a laminated electrode.

5) Preparation of cathode

Silicon oil was injected into the electric furnace, and indium and lithium were charged into the silicone oil at a mass ratio of 95: 5, followed by heat treatment at 200 占 폚. At this time, a stirrer was charged so that indium and lithium were dissolved and dispersed evenly in the silicone oil.

The emulsified indium and lithium were extracted and dried to prepare a metal powder having a particle size of 6 탆.

The metal powder was dry mixed with the solid electrolyte at a weight ratio of 80:20 for 12 hours, then placed on a nickel foil (current collector), and then pressed using a mold to produce a negative electrode.

6) Fabrication of battery cell

The prepared two types of electrodes were stacked so that a solid electrolyte layer was interposed between the positive electrode and the negative electrode, and then the density was increased by hot pressing at a pressure and a temperature of 5000 kgf and 200 ° C to prepare a battery cell.

A laminate-type pouch was used as a casing of the battery cell, and a battery cell was inserted into the casing, followed by vacuum sealing to complete the manufacturing process of the entire solid battery.

Comparative Example

All solid batteries were prepared in the same manner except that lithium foil was used as a cathode in comparison with the above example.

Measurement example

The electrochemical performance evaluation of all the solid batteries produced by the above-described Examples and Comparative Examples was carried out. Evaluation of all solid cells at 0.2 C based on the anode capacity was performed.

Referring to FIG. 2, it can be seen that the discharge capacity of the all-solid-state battery of the embodiment is 120 mAh / g, which is twice the discharge capacity of the all-solid-state battery of the comparative example.

Accordingly, the entire solid-state cell according to the present invention has improved the output performance by maximizing the interface area between the solid electrolyte layer and the cathode and the reaction area within the cathode by powdering the sheet-like or foil-shaped metal-based material used as the anode active material I could.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Modified forms are also included within the scope of the present invention.

10: anode
11: cathode active material
13: Conductive material
15: binder
17: Solid electrolyte
20: solid electrolyte layer
30: cathode
31: Lithium powder
33: indium powder

Claims (8)

A positive electrode comprising a positive electrode active material,
A negative electrode comprising a metal powder in which lithium powder and indium powder are mixed, and
A solid electrolyte cell comprising a solid electrolyte layer.
The method according to claim 1,
Wherein the lithium powder and the indium powder are mixed in a mass ratio of 5:95 to 50:50.
The method according to claim 1,
Wherein the negative electrode further comprises a solid electrolyte,
Wherein the metal powder and the solid electrolyte are contained in the cathode in a mass ratio of 50:50 to 95: 5.
Preparing a positive electrode composite;
Preparing an electrolyte slurry;
Forming a laminated electrode by sequentially coating the anode composite and the electrolyte slurry on a substrate;
Preparing a metal powder by mixing a lithium powder and an indium powder by a wet process, and pressing the metal powder to a current collector to prepare a negative electrode; And
And pressing the laminated electrode and the negative electrode to manufacture a battery cell.
5. The method of claim 4,
Wherein the positive electrode composite is a mixture of a positive electrode active material, a solid electrolyte, a conductive material and a binder.
5. The method of claim 4,
Wherein the electrolyte slurry is a mixture of a solid electrolyte and a binder.
5. The method of claim 4,
Wherein the lithium powder and the indium powder are mixed in a mass ratio of 5:95 to 50:50.
5. The method of claim 4,
Wherein the metal powder is mixed with a solid electrolyte at a mass ratio of 50:50 to 95: 5 and then press-molded into the current collector.

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