KR102595758B1 - Sintering aid of solid electrolyet for solid-state battery and solid electrolyet comprising the same - Google Patents

Abstract

The present invention relates to a sintering aid for a solid electrolyte for an all-solid-state battery and a solid electrolyte containing the same. The solid electrolyte for an all-solid-state battery according to an embodiment of the present invention includes a solid electrolyte with a nasicone-type crystal structure and a sintering aid, and the sintering aid is made of an oxide containing Li, Ag, and V.

Description

Sintering aid for solid electrolyte for all-solid-state battery and solid electrolyte containing same {SINTERING AID OF SOLID ELECTROLYET FOR SOLID-STATE BATTERY AND SOLID ELECTROLYET COMPRISING THE SAME}

The present invention relates to a sintering aid for a solid electrolyte for an all-solid-state battery and a solid electrolyte containing the same.

Recently, the use of secondary batteries has increased significantly in various fields, from IT devices such as mobile phones to electric vehicles and energy storage devices.

As secondary batteries, lithium-ion batteries using liquid electrolyte are most widely used. However, liquid electrolyte has a risk of leakage when external shock is applied to the battery, and thus additional parts and devices are needed to ensure safety.

Recently, in order to improve the safety of secondary batteries, development of all-solid-state batteries that use solid electrolytes as electrolytes is actively underway. Solid electrolytes in all-solid-state batteries include polymer electrolytes, oxide electrolytes, and sulfide electrolytes. Among these, sulfide-based solid electrolytes have the highest ionic conductivity, but have the problem of generating hydrogen sulfide gas when they react with moisture. Polymer electrolytes have the advantage of having a relatively simple process and being able to use existing lithium-ion battery processes, but have the disadvantage of having significantly low ionic conductivity.

Oxide-based electrolytes have lower ionic conductivity than sulfide-based electrolytes, but are relatively high and have the advantage of excellent safety. However, oxide-based electrolytes generally require a high sintering temperature of 1,000°C or more, which can significantly increase manufacturing costs.

The present invention is intended to solve the problems of the prior art described above, and its purpose is to provide a sintering aid that can sinter an oxide-based electrolyte at low temperature and has excellent ionic conductivity, and a solid electrolyte containing the same.

The solid electrolyte for an all-solid-state battery according to an embodiment of the present invention includes a solid electrolyte with a nasicone-type crystal structure and a sintering aid, and the sintering aid is made of an oxide containing Li, Ag, and V.

According to one embodiment of the present invention, the sintering aid may be prepared from 45-61 mol% of Li ₂ O, 25-40 mol% of V ₂ O ₅ , and 6-25 mol% of Ag ₂ O.

According to one embodiment of the present invention, the sintering aid includes Li ₂ O, V ₂ O ₅ and Ag ₂ O, and the molar ratio of Li ₂ O, V ₂ O ₅ and Ag ₂ O may be 2:1:1. there is.

The sintering temperature of the solid electrolyte for an all-solid-state battery according to an embodiment of the present invention may be 550°C or lower.

The ion conductivity of the solid electrolyte for an all-solid-state battery according to an embodiment of the present invention at room temperature may be 0.3 X 10 ^-5 to 1.4 X 10 ^-4 S/cm.

According to one embodiment of the present invention, the solid electrolyte with a nasicone-type crystal structure may be a LAGP solid electrolyte or a LATP solid electrolyte.

The sintering aid for the solid electrolyte for an all-solid-state battery according to an embodiment of the present invention is composed of oxides containing Li, Ag, and V.

In addition to this, the solid electrolyte and sintering aid for an all-solid-state battery according to the present invention may further include other additional components without impairing the technical spirit of the present invention.

According to one embodiment of the present invention, low-temperature sintering of a solid electrolyte is possible through a sintering aid containing Li, Ag, and V. Additionally, a solid electrolyte containing such a sintering aid may have excellent ionic conductivity.

1 is a diagram schematically showing a cross section of an all-solid-state battery.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail so that a person skilled in the art can easily implement the present invention.

In order to clearly explain the present invention, descriptions of parts unrelated to the present invention have been omitted, and like reference numerals are assigned to like components throughout the specification. The specific shape, structure, and characteristics described in the specification may be changed and implemented from one embodiment to another without departing from the spirit and scope of the present invention, and the location or arrangement of individual components may also be implemented within the spirit and scope of the present invention. It should be understood as something that can be changed without deviating from it.

Accordingly, the detailed description described below is not to be taken in a limiting sense, and the scope of the present invention should be taken to encompass the scope of the claims and all equivalents thereof.

1 is a diagram schematically showing a cross section of an all-solid-state battery.

Referring to FIG. 1, the all-solid-state battery 10 includes an anode 11, a cathode 12, and a solid electrolyte layer 13. The solid electrolyte layer 13 is disposed between the anode 11 and the cathode 12 and may be in contact with the anode 11 and the cathode 12, respectively. The positive electrode 11 and the negative electrode 12 may each have a positive electrode active material layer and a negative electrode active material layer, and the positive electrode active material layer and the negative electrode active material layer may each be in contact with the solid electrolyte layer 13.

The anode 11 and the cathode 12 may each be bonded to the solid electrolyte layer 13 by sintering. That is, the anode 11, cathode 12, and solid electrolyte layer 13 can be sintered as one piece.

In Figure 1, the all-solid-state battery 10 is shown as including one layer each of the anode 11, the cathode 12, and the solid electrolyte layer 13, but the present invention is not limited thereto and includes the anode, the cathode, and the solid electrolyte layer. An all-solid-state battery may be constructed in a form in which the solid electrolyte layer is each composed of a plurality of layers. Alternatively, it may be configured as a so-called stacked all-solid-state battery in which a plurality of anodes, cathodes, and solid electrolyte layers are alternately stacked.

The solid electrolyte layer 13 according to an embodiment of the present invention includes an oxide-based electrolyte as a solid electrolyte. In one embodiment, the solid electrolyte may include an oxide having a Nasicon-type crystal structure. In one embodiment, the oxide of nasicone-type crystal structure is LAGP (Li _1+x Al _x Ge _2-x (PO ₄ ) ₃ ) or LATP (Li _1+x Al _x Ti _2-x (PO ₄ ) ₃ ). You can.

The solid electrolyte included in the solid electrolyte layer 13 according to an embodiment of the present invention further includes a sintering aid.

Typically, oxide-based electrolytes with a nasicone-type crystal structure are sintered at a high temperature of 1,000°C or higher. In this case, as described above, some excellent ionic conductivity can be obtained, but an increase in manufacturing cost due to high temperature sintering cannot be avoided.

In one embodiment of the present invention, by adding a sintering aid to an oxide-based electrolyte with a Nasicon-type crystal structure, excellent ionic conductivity can be secured while significantly lowering the sintering temperature.

The sintering aid according to an embodiment of the present invention may be composed of a compound containing Li, V, and Ag. For example, the sintering aid according to an embodiment of the present invention may include Li ₂ O, V ₂ O ₅ and Ag ₂ O.

In the oxide that forms the sintering aid, Li ₂ O serves to provide Li ions and improve ionic conductivity.

V ₂ O ₅ is a temperature lowering component and plays a role in lowering the sintering temperature. Additionally, V ions exist as pentavalent ions, so as V ions increase, nonbridging oxygen increases and additional ion flow paths are created in the network structure, thereby improving ionic conductivity.

Ag ₂ O serves to lower the sintering temperature and also acts as a network modifier within the compound. Ag ₂ O can improve ionic conductivity by disconnecting the main glass-forming network and enabling the flow of conductive ions.

In this way, the sintering aid according to an embodiment of the present invention includes Li ₂ O, V ₂ O ₅ and Ag ₂ O, so that V ₂ O ₅ can function as the main glass former and expand the flow path of Li ions. , Ag ₂ O can play a role in breaking the glass network and lowering the sintering temperature.

The sintering temperature of the sintering aid according to one embodiment of the present invention is about 500°C to about 600°C. The sintering aid according to an embodiment of the present invention exhibits ^an ionic conductivity of about ^1.5

The solid electrolyte according to an embodiment of the present invention may include 95% by mass or more of an oxide-based electrolyte with a Nasicon-type crystal structure and 5% by mass or less of a sintering aid. When the solid electrolyte according to an embodiment of the present invention is sintered at 500° ^C to 600°C, the ionic conductivity is about ^1.4

Below, the present invention will be described in more detail with reference to specific examples and test examples of the present invention.

[Example]

Example 1

A precursor powder for the production of a sintering aid was prepared by mixing 48 mol% of Li ₂ O, 27 mol% of V ₂ O ₅ and 25 mol% of Ag ₂ O. After mixing the precursor powder, it was placed in a melting furnace and melted at a temperature of about 1,100°C for about 1 hour. Afterwards, the homogenized melt was poured onto a quenching roller, cooled to room temperature, pulverized, and then sieved to obtain a sintering aid in the form of cullet with a size of 200 ㎛ or less.

Additional Examples and Comparative Examples

Precursor powder was prepared by varying the composition ratios of Li ₂ O, V ₂ O ₅ 25 and Ag ₂ O, and melted at a temperature of 800°C to 1,200°C for about 1 hour depending on the composition ratio, and then through the same process as Example 1. A sintering aid in the form of cullet was obtained.

The composition ratio of the sintering aid according to each of the examples and comparative examples described above is as shown in Table 1.

division Sintering aid composition (mol%) Melting temperature (℃) Li ₂ O V ₂ O ₅ Ag ₂ O Example 1 50 25 25 1,100 Example 2 48 27 25 1,100 Example 3 50 40 10 1,100 Example 4 61 33 6 1,100 Comparative Example 1 40 59 One 1,000 Comparative Example 2 40 60 0 1,000 Comparative Example 3 38 57 5 1,000 Comparative Example 4 36 54 10 1,000

The sintering aids of Examples and Comparative Examples in Table 1 were mixed with LAGP and sintered to prepare a solid electrolyte. Specifically, about 3% by mass of the sintering aid of each Example and Comparative Example was mixed with about 97% by mass of Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ and sintered at about 550° C. for about 12 hours to prepare a solid electrolyte. .

The results of measuring the transition point, crystallization temperature, and ionic conductivity of the solid electrolyte prepared as above are shown in Table 2.

division transition point
(℃) crystallization temperature
(℃) ionic conductivity
(S/cm) Example 1 367 390 ^1.46 Example 2 376 391 ^9.76 Example 3 380 385 ^8.00 Example 4 367 390 ^3.19 Comparative Example 1 551 583 ^3.16 Comparative Example 2 541 584 ^1.63 Comparative Example 3 460 473 ^2.57 Comparative Example 4 443 454 ^2.05

Referring to Table 2, it is confirmed that the solid electrolyte prepared including the sintering aid according to Examples 1 to 4 of the present invention has a transition point of 380°C or less and a crystallization temperature of 400°C or less. In comparison, the solid electrolyte prepared including the sintering aid according to Comparative Examples 1 to 4 has a transition point of 440°C or higher and a crystallization temperature of 450°C or higher. That is, it can be confirmed that the solid electrolyte prepared including the sintering aid according to Examples 1 to 4 has characteristics enabling low-temperature sintering.

The solid electrolyte prepared including the sintering aid according to Examples 1 to 4 of the present invention had an ionic conductivity of ^3.19 Solid electrolytes have ionic conductivities less than this. In particular, including the sintering aid according to Example 1 (i.e., a sintering aid comprising 50 mol% of Li ₂ O, 25 mol% of V ₂ O ₅ , and 25 mol% of Ag ₂ O at a molar ratio of 2:1:1) It was confirmed that the prepared solid electrolyte showed remarkably excellent ionic conductivity.

Although the present invention has been described above with reference to specific details such as specific components and limited examples, the examples are provided only to facilitate a more general understanding of the present invention, and the present invention is not limited thereto. Anyone with ordinary knowledge in the relevant technical field can make various modifications and transformations from this description.

Accordingly, the spirit of the present invention should not be limited to the embodiments described above, and all modifications equivalent to or equivalent to the claims as well as the claims described below shall fall within the scope of the spirit of the present invention. will be.

10: All-solid-state battery
11: anode
12: cathode
13: solid electrolyte layer

Claims (9)

Contains a solid electrolyte and a sintering aid with a nasicon-type crystal structure,
The sintering aid consists of oxides containing Li, Ag, and V,
The sintering aid is manufactured from 45-61 mol% of Li ₂ O, 25-40 mol% of V ₂ O ₅ , and 6-25 mol% of Ag ₂ O.
Solid electrolyte for all-solid-state batteries. delete According to paragraph 1,
The sintering aid includes Li ₂ O, V ₂ O ₅ and Ag ₂ O, and the molar ratio of Li ₂ O, V ₂ O ₅ and Ag ₂ O is 2:1:1,
Solid electrolyte for all-solid-state batteries. According to paragraph 1,
A solid electrolyte for an all-solid-state battery having a sintering temperature of 550°C or lower. According to paragraph 1,
^Ionic conductivity at room temperature is ^0.3
Solid electrolyte for all-solid-state batteries. According to paragraph 1,
The solid electrolyte of the Nasicon type crystal structure is a LAGP solid electrolyte or a LATP solid electrolyte.
Solid electrolyte for all-solid-state batteries. As a sintering aid for a solid electrolyte for an all-solid-state battery,
It consists of oxides containing Li, Ag and V,
Prepared from 45-61 mol% of Li ₂ O, 25-40 mol% of V ₂ O ₅ and 6-25 mol% of Ag ₂ O,
Sintering aid. delete In clause 7,
Comprising Li ₂ O, V ₂ O ₅ and Ag ₂ O, and the molar ratio of Li ₂ O, V ₂ O ₅ and Ag ₂ O is 2:1:1,
Sintering aid.

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