Solid electrolyte powder for all-solid batteries

Abstract

The present invention relates to a solid electrolyte powder for all-solid-state batteries. An embodiment of the present invention may include a crystalline powder comprising at least one of an amorphous powder containing Li, B, Al oxides and LiCl, a first crystalline powder containing Li, B, Al oxides and LiCl, and a second crystalline powder containing Li, B oxides and LiCl.

Description

Technical Field

[0001] The present invention relates to a solid electrolyte powder for all-solid-state batteries.

Background Art

[0002] 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. [[ID=1 and 14]]

[0003] As secondary batteries, lithium-ion batteries using a liquid electrolyte are most widely used. However, the liquid electrolyte has a risk of leakage when the battery is subjected to an external impact, and accordingly, additional components and devices are required to ensure safety.

[0004] Recently, in order to improve the safety of secondary batteries, the development of all-solid-state batteries using a solid electrolyte as an electrolyte has been actively carried out. As the solid electrolyte of an all-solid-state battery, there are a polymer-based electrolyte, an oxide-based electrolyte, a sulfide-based electrolyte, etc. Among these, the sulfide-based solid electrolyte has the highest ionic conductivity, but has a problem that it reacts with moisture to generate hydrogen sulfide gas. The polymer-based electrolyte has the advantage that the process is relatively simple and the existing lithium-ion battery process can be used, but has the disadvantage that the ionic conductivity is significantly low. <000 at the end of 017>

[0005] The oxide-based electrolyte has a lower ionic conductivity than the sulfide-based electrolyte, but has the advantage of excellent electrochemical safety. However, the oxide-based electrolyte usually requires a high sintering temperature of 1,000 °C or higher, which can significantly increase the manufacturing cost. Various attempts have been made to lower the sintering temperature of the oxide-based electrolyte, but in fact, it is still necessary to lower the sintering temperature while solving the accompanying problems.

Summary of the Invention

Problems to be Solved by the Invention

[0007] Furthermore, the present invention aims to eliminate the side effects associated with a low sintering temperature while using a solid electrolyte powder composed of an oxide containing Li, B, Al, and LiCl. [Means for solving the problem]

[0008] A solid electrolyte powder for an all-solid-state battery according to one embodiment of the present invention may include an amorphous powder containing Li, B, Al oxides and LiCl; and a crystalline powder containing at least one of a first crystalline powder containing Li, B, Al oxides and LiCl and a second crystalline powder containing Li, B oxides and LiCl.

[0009] According to one embodiment of the present invention, the crystalline powder may contain at least 0.5 mol%.

[0010] According to one embodiment of the present invention, the amorphous powder may contain 20-35 mol% Li2O, 30-40 mol% B2O3, 10-20 mol% Al2O3, and 15-25 mol% LiCl.

[0011] According to one embodiment of the present invention, the first crystalline powder may contain 20-35 mol% Li2O, 30-40 mol% B2O3, 10-20 mol% Al2O3, and 15-25 mol% LiCl.

[0012] According to one embodiment of the present invention, the second crystallized powder may contain 20-35 mol% Li2O, 30-40 mol% B2O3, and 15-25 mol% LiCl.

[0013] According to one embodiment of the present invention, amorphous powder can be produced from Li2CO3, LiCl, H3BO3, and Al2O3 precursors.

[0014] According to one embodiment of the present invention, the first crystalline powder can be produced from Li2CO3, LiCl, H3BO3, and Al2O3 precursors.

[0015] According to one embodiment of the present invention, the second crystallized powder can be produced from Li2CO3, LiCl, and H3BO3 precursors.

[0016] According to one embodiment of the present invention, a solid electrolyte for an all-solid-state battery can be produced by a manufacturing method comprising: producing amorphous powder from Li2CO3, LiCl, H3BO3, and Al2O3 precursors; crystallizing the amorphous powder to produce a first crystallized powder and crystallizing LCB powder to produce a second crystallized powder; mixing the amorphous powder with a crystallized powder containing at least one of the first crystallized powder and the second crystallized powder to produce a mixed powder; and sintering the mixed powder. [Effects of the Invention]

[0017] A solid electrolyte for an all-solid-state battery according to one embodiment of the present invention can be sintered at low temperatures while possessing excellent ionic conductivity.

[0018] In particular, a solid electrolyte powder consisting of oxides containing Li, B, Al, and LiCl can be used to lower the sintering temperature while eliminating problems such as side reactions with the cathode material. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic diagram showing a cross-section of an all-solid-state battery.

[0020] [Figure 2] This flowchart shows a method for producing a solid electrolyte for an all-solid-state battery according to one embodiment of the present invention.

[0021] [Figure 3] This diagram schematically illustrates the action of nucleating agents. [Modes for carrying out the invention]

[0022] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail to such an extent that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it.

[0023] To clearly explain the present invention, descriptions of parts not related to the present invention will be omitted, and the same reference numerals will be assigned to the same components throughout the specification.

[0024] The detailed description to be described later is not made in a limiting sense, and the scope of the present invention should be understood to include the scope claimed by the claims of the claims and all equivalent ranges thereto.

[0025] FIG. 1 is a drawing schematically showing a cross section of a all-solid-state battery.

[0026]

[0027] Referring to FIG. 1, the all-solid-state battery 10 includes a positive electrode 11, a negative electrode 12, and a solid electrolyte layer 13. The solid electrolyte layer 13 is disposed between the positive electrode 11 and the negative electrode 12 and can be in contact with the positive electrode 11 and the negative electrode 12 respectively. The positive electrode 11 and the negative electrode 12 can each include 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 can be in contact with the solid electrolyte layer 13 respectively.

[0028] The positive electrode 11 and the negative electrode 12 can be joined to the solid electrolyte layer 13 by sintering respectively. That is, the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13 can be integrally sintered.

[0029] In FIG. 1, the all-solid-state battery 10 is illustrated in a form including one layer each of the positive electrode 11, the negative electrode 12, and the solid electrolyte layer 13, but the present invention is not limited thereto, and the all-solid-state battery may be configured in a form in which the positive electrode, the negative electrode, and the solid electrolyte layer each consist of a plurality of layers. Or it may be configured as a so-called laminated all-solid-state battery in a form in which a plurality of the positive electrode, the negative electrode, and the solid electrolyte layer are alternately laminated.

[0030] The solid electrolyte layer 13 according to one embodiment of the present invention can be manufactured from a solid electrolyte powder. The solid electrolyte according to one embodiment of the present invention consists of an oxide-based solid electrolyte, and the solid electrolyte powder according to one embodiment of the present invention may contain an oxide-based powder.

[0031] Oxide-based solid electrolytes include Nasicon-type electrolytes such as LAGP and Garnet-type electrolytes such as LLZO. Through continuous research and development, the ionic conductivity of such oxide-based solid electrolytes has been increased to 10. -4 It is known to have improved to the S / cm level.

[0032] However, there are limits to further improving the ionic conductivity of the aforementioned NASCICON and garnet-type oxide solid electrolytes. Moreover, since these oxide solid electrolytes are usually sintered at high temperatures of 1,000°C or higher, although a certain degree of excellent ionic conductivity can be obtained, as mentioned above, it is impossible to avoid the increased manufacturing costs due to high-temperature sintering.

[0033] In one embodiment of the present invention, a new oxide-based solid electrolyte overcomes the limitations of conventional oxide-based solid electrolytes, thereby ensuring excellent ionic conductivity while maintaining a low sintering temperature.

[0034] A solid electrolyte powder for an all-solid-state battery according to one embodiment of the present invention may comprise an amorphous powder and a crystalline powder. In one embodiment, the amorphous powder may include oxides of Li, B, Al, and LiCl. In one embodiment, the crystalline powder may comprise at least one of a first crystalline powder containing oxides of Li, B, Al, and LiCl, and a second crystalline powder containing oxides of Li, B, and LiCl.

[0035] In this specification, powders containing oxides of Li, B, Al, and LiCl are referred to as LCBA powder, and powders containing oxides of Li, B, and LiCl are referred to as LCB powder.

[0036] Thus, the solid electrolyte powder for an all-solid-state battery according to one embodiment of the present invention comprises an amorphous powder containing LCBA powder and a crystalline powder containing at least one of a first crystalline powder containing LCBA powder and a second crystalline powder containing LCB powder.

[0037] An LCBA powder according to one embodiment of the present invention contains Li2O, B2O3, Al2O3, and LiCl, and an LCB powder may contain Li2O, B2O3, and LiCl.

[0038] In solid electrolyte compositions, Li2O can function as a network modifier, providing Li ions and thereby improving ionic conductivity.

[0039] In a solid electrolyte composition, B2O3 can function as a network-forming agent and is a low-temperature component that lowers the sintering temperature.

[0040] In solid electrolyte compositions, Al2O3 can function as a network modifier, increasing the lattice constant of the boron oxide crystal structure. Consequently, a wider range of Li ion migration pathways can be secured in the crystal structure, thereby improving ionic conductivity.

[0041] In the composition of a solid electrolyte, LiCl increases the amount of Li ions in the solid electrolyte, thereby improving ionic conductivity. Cl ions enter the network structure, forming a network structure in which two types of anions coexist, and thus expanding the volume of the network structure.

[0042] On the other hand, as mentioned above, oxide-based solid electrolytes require simultaneous firing with the positive and negative electrodes. During this simultaneous firing process, there is a risk of oxidation of the conductive material or reaction with the positive and negative electrode materials, necessitating a lower sintering temperature. In the case of amorphous LCBA powder, the sintering temperature can be lowered to approximately 490°C. However, it has been confirmed that sintering at 490°C or higher may result in side reactions with the positive electrode material.

[0043] In this invention, in order to solve such side reaction problems while keeping the sintering temperature low, a solid electrolyte powder is constructed by including crystalline powder in amorphous powder.

[0044] Figure 2 is a flowchart showing a method for producing a solid electrolyte for an all-solid-state battery according to one embodiment of the present invention.

[0045] According to one embodiment of the present invention, a method for producing a solid electrolyte for an all-solid-state battery includes the steps of: producing amorphous powder (S1); producing crystalline powder (S2); producing a mixed powder by mixing amorphous powder with crystalline powder (S3); and sintering the mixed powder (S4).

[0046] In step (S1), a precursor powder made by mixing Li2CO3, LiCl, H3BO3, and Al2O3 is pulverized and then melted. The molten material is then cooled and pulverized into fine particles to produce LCBA amorphous powder.

[0047] According to one embodiment of the present invention, the LCBA amorphous powder may contain 20-35 mol% Li2O, 30-40 mol% B2O3, 10-20 mol% Al2O3, and 15-25 mol% LiCl.

[0048] In step (S2), a crystallized powder is produced. According to one embodiment of the present invention, the crystallized powder comprises at least one of a first crystallized powder containing LCBA powder and a second crystallized powder containing LCB powder. That is, the first crystallized powder can be produced by crystallizing the aforementioned LCBA amorphous powder, and the second crystallized powder can be produced by crystallizing LCB amorphous powder.

[0049] Here, LCB powder is produced by pulverizing a precursor powder mixed with Li2CO3, LiCl, and H3BO3, melting it, and then cooling the molten material to pulverize it into fine particles. According to one embodiment of the present invention, the LCB powder may contain 20-35 mol% Li2O, 30-40 mol% B2O3, and 15-25 mol% LiCl.

[0050] According to one embodiment of the present invention, each powder can be crystallized by heat treatment at a temperature of 600°C.

[0051] In step (S3), the crystalline powder is mixed with the amorphous LCBA powder. Here, the crystalline powder may contain at least one of the first crystalline powder and the second crystalline powder, and the crystalline powder can function as a nucleating agent. According to one embodiment of the present invention, the crystalline powder used as a nucleating agent may be added to the amorphous powder in an amount of 0.5 to 5 mol%.

[0052] In step (S4), the mixed powder is sintered to produce a solid electrolyte. According to one embodiment of the present invention, low-temperature sintering is possible by sintering a mixed powder of amorphous powder and crystalline powder.

[0053] Figure 3 is a schematic diagram illustrating the action of a nucleating agent in the crystallization of amorphous powder. The effects of crystallization and sintering when crystallizing powder is included will be explained with reference to this diagram.

[0054] Referring to Figure 3, when a nucleating agent is added (see lower part of Figure 3), the number of nucleation sites increases compared to when no nucleating agent is added (see upper part of Figure 3). Consequently, when a nucleating agent is added, the crystallization of the powder is promoted, and the degree of crystallinity can increase for the same heat treatment. This increase in crystallinity allows the solid electrolyte powder to crystallize with less heat, thereby lowering the sintering temperature of the solid electrolyte powder.

[0055] According to one embodiment of the present invention, a crystalline powder, which has been pre-crystallized, can be added to an amorphous powder of a solid electrolyte powder and used as a nucleating agent. According to this embodiment, a first crystalline powder and / or a second crystalline powder can be used as a nucleating agent. Specifically, a crystalline powder containing at least one of the first crystalline powder and the second crystalline powder is added to an amorphous powder in a predetermined ratio to produce a mixed powder, and the mixed powder is sintered to produce a solid electrolyte for an all-solid-state battery. In this embodiment, the crystalline powder can be added to the amorphous powder in an amount of at least 0.5 wt%.

[0056] According to one embodiment of the present invention, a mixed powder containing crystalline LCBA powder and / or LCA powder as a nucleating agent can preferably have a sintering temperature of 485°C or lower.

[0057] [Examples]

[0058] Amorphous LCBA powder was prepared from precursors containing Li2CO3, LiCl, H3BO3, and Al2O3, and LCB powder was prepared from precursors containing Li2CO3, LiCl, and H3BO3. After mixing the respective precursor powders, they were placed in an Al crucible and melted at approximately 1,000°C for 30 minutes. The molten material was rapidly cooled on a quenching roller, pulverized, and then sieved to obtain fine particles with a size of 10 μm or less.

[0059] Subsequently, six types of mixed powders were produced by varying the type and ratio of crystalline powder added to the LCBA amorphous powder.

[0060] [Comparative Example]

[0061] A comparative example was prepared in which amorphous LCBA powder was obtained through the same process as in the above example, but without the addition of crystalline powder.

[0062] The sintering temperature (Tx) of the solid electrolyte powders in the above examples and comparative examples was measured using a thermal analysis device (STD). Furthermore, the degree of crystallinity, crystal size, and ratio of each crystalline phase after crystallization of each mixed powder at 600°C for 3 hours were measured using an X-ray diffraction analyzer (XRD). The sintering temperatures and degree of crystallinity for each example and comparative example are summarized in Table 1.

[0063] The sintering temperature (Tx) of the solid electrolyte powders in the above examples and comparative examples was measured using a thermal analysis device (STD). Furthermore, the degree of crystallinity, crystal size, and ratio of each crystalline phase after crystallization of each mixed powder at 600°C for 3 hours were measured using an X-ray diffraction analyzer (XRD). The sintering temperatures and degree of crystallinity for each example and comparative example are summarized in Table 1.

[0064] [Table 1]

[0065] In Table 1, the total crystallinity represents the proportion of crystalline material in the total powder. For example, a total crystallinity of 72 means that 72% of the total powder is crystalline and the remaining 28% is amorphous.

[0066] Furthermore, in Table 1, the crystallinity of LCBA and LCB represents the crystalline ratio of each component. For example, if the crystallinity of LCBA is 75.6 and the crystallinity of LCB is 24.4, it means that 75.6% of the total powder's crystalline content consists of LCBA crystals and 24.4% consists of LCB crystals.

[0067] In the comparative example, the total crystallinity was shown to be 72. In contrast, the total crystallinity in Examples 1 to 6 was 73 to 77, indicating an increase. Furthermore, the total crystallinity after 600°C heat treatment tends to increase as the addition ratio of crystallized LCBA powder increases. Additionally, the crystallinity ratio of the LCBA component tends to decrease and the crystallinity ratio of the LCB component tends to increase as the addition ratio of the first crystallized powder increases.

[0068] Furthermore, it can be confirmed that the sintering temperature is lowered to less than 490°C in Examples 1 to 6. As mentioned above, side reaction problems between the solid electrolyte and the cathode material occur at sintering temperatures of 490°C or higher. Therefore, in the examples where the sintering temperature is lowered, the side reaction problem between the solid electrolyte and the cathode material in conventional oxide solid electrolytes can be solved.

[0069] Thus, the solid electrolyte according to the present invention can not only suppress the increase in production costs due to the high sintering temperature of conventional oxide solid electrolytes, but also solve the problem of side reactions with the cathode material during the sintering process.

[0070] Although the present invention has been described above with reference to specific components and limited embodiments, these embodiments are provided merely to aid in a more general understanding of the present invention, and the present invention is not limited thereto. Anyone with ordinary skill in the art to which the present invention belongs can attempt various modifications and variations from this description.

[0071] Therefore, the concept of the present invention should not be limited to the embodiments described above, and it can be said that not only the claims described below, but also all modifications equivalent to or equivalent to these claims, fall within the scope of the concept of the present invention. [Explanation of symbols]

[0072] 10: All-solid-state battery

[0073] 11: Positive electrode

[0074] 12: Negative electrode

[0075] 13: Solid electrolyte layer

Claims

1. A solid electrolyte powder for all-solid-state batteries, Amorphous powder containing Li, B and Al oxides and LiCl A crystallized powder comprising at least one of a first crystallized powder containing Li, B and Al oxides and LiCl, and a second crystallized powder containing Li and B oxides and LiCl; A solid electrolyte powder containing the following:

2. The solid electrolyte powder according to claim 1, comprising at least 0.5 wt% of the crystalline powder.

3. The amorphous powder is 20-35 mol% Li ２ O, 30-40 mol% B ２ O ３ , 10-20 mol% Al ２ O ３ and the solid electrolyte powder according to claim 1, comprising 15 to 25 mol% LiCl.

4. The first crystalline powder is 20 to 35 mol% of Li ２ O, 30 to 40 mol% of B ２ O ３ 、10 to 20 mol% of Al ２ O ３ The solid electrolyte powder according to claim 1, comprising 15 to 25 mol% of LiCl.

5. The aforementioned second crystalline powder is 20-35 mol% Li ２ O, 30-40 mol% B ２ O ３ and the solid electrolyte powder according to claim 1, comprising 15 to 25 mol% LiCl.

6. The amorphous powder is Li ２ CO ３ LiCl, H ３ BO ３ and Al ２ O ３ A solid electrolyte powder according to claim 1, manufactured from a precursor.

7. The first crystalline powder is Li ２ CO ３ LiCl, H ３ BO ３ and Al ２ O ３ A solid electrolyte powder according to claim 1, manufactured from a precursor.

8. The aforementioned second crystalline powder is Li ２ CO ３ , LiCl and H ３ BO ３ A solid electrolyte powder according to claim 1, manufactured from a precursor.

9. A method for manufacturing a solid electrolyte for an all-solid-state battery, Li ２ CO ３ LiCl, H ３ BO ３ and Al ２ O ３ The step of producing amorphous powder from a precursor; A step of producing a first crystalline powder by crystallizing the amorphous powder, and producing a second crystalline powder by crystallizing the LCB powder; A step of producing a mixed powder by mixing the amorphous powder with a crystallized powder containing at least one of the first crystallized powder and the second crystallized powder; and A method for producing a solid electrolyte for an all-solid-state battery, comprising the step of sintering the mixed powder.

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