Solid electrolyte powder for all-solid-state battery

Abstract

The present invention relates to a solid electrolyte powder for an all-solid-state battery. The solid electrolyte for an all-solid-state battery, according to one embodiment of the present invention, may comprise: amorphous powder including LiCl and oxides of Li, B and Al; and crystallized powder including a first crystallized powder including LiCl and oxides of Li, B and Al, and / or a second crystallized powder including LiCl and oxides of Li and B.

Description

Solid electrolyte powder for all-solid-state batteries

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

[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.

[0003] Lithium-ion batteries, which use liquid electrolytes, are the most widely used secondary batteries. However, liquid electrolytes pose a risk of leakage if the battery is subjected to external shocks, necessitating the use of additional components and devices to ensure safety.

[0004] Recently, active development of all-solid-state batteries using solid electrolytes has been underway to improve the safety of secondary batteries. Solid electrolytes for all-solid-state batteries include polymer electrolytes, oxide electrolytes, and sulfide electrolytes. Sulfide solid electrolytes have the highest ionic conductivity, but they have the problem of reacting with moisture to produce hydrogen sulfide gas. Polymer electrolytes offer the advantages of a relatively simple process and compatibility with existing lithium-ion battery processes, but their significantly low ionic conductivity is a drawback.

[0005] Oxide-based electrolytes have lower ionic conductivity than sulfide-based electrolytes, but offer the advantage of superior electrochemical safety. However, oxide-based electrolytes typically require high sintering temperatures, typically exceeding 1,000°C, which can significantly increase manufacturing costs. Various attempts have been made to lower the sintering temperature of oxide-based electrolytes, but the need to lower the sintering temperature while addressing the associated issues remains.

[0006] The present invention is intended to solve the problems of the prior art described above, and its purpose is to provide a solid electrolyte powder for an all-solid-state battery that can be sintered at low temperature and has excellent ionic conductivity.

[0007] In addition, the present invention aims to lower the sintering temperature in a solid electrolyte powder composed of an oxide including Li, B, Al, and LiCl while eliminating side effects resulting therefrom.

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

[0009] According to one embodiment of the present invention, the crystallized powder may be included in an amount of at least 0.5 mol%.

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

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

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

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

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

[0015] According to one embodiment of the present invention, the second crystallization powder can be prepared 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 manufactured through a manufacturing method including the steps of: manufacturing an amorphous powder from Li2CO3, LiCl, H3BO3, and Al2O3 precursors; crystallizing the amorphous powder to manufacture a first crystallized powder and crystallizing LCB powder to manufacture a second crystallized powder; mixing a crystallized powder including at least one of the first crystallized powder and the second crystallized powder into the amorphous powder to manufacture a mixed powder; and sintering the mixed powder.

[0017] A solid electrolyte for an all-solid-state battery according to one embodiment of the present invention can have excellent ionic conductivity while being capable of low-temperature sintering.

[0018] In particular, it is possible to resolve problems such as side reactions with the cathode material while lowering the sintering temperature in a solid electrolyte powder composed of oxides including Li, B, Al, and LiCl.

[0019] Figure 1 is a drawing schematically showing a cross-section of an all-solid-state battery.

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

[0021] Figure 3 is a diagram schematically showing the action of a nucleating agent.

[0022] [Explanation of symbols]

[0023] 10: All-solid-state batteries

[0024] 11: Bipolar

[0025] 12: Cathode

[0026] 13: Solid electrolyte layer

[0027] Hereinafter, with reference to the attached drawings, a preferred embodiment of the present invention will be described in detail to a degree that a person having ordinary skill in the art to which the present invention pertains can easily practice the present invention.

[0028] In order to clearly explain the present invention, the description of parts unrelated to the present invention is omitted, and the same reference numerals are used for the same components throughout the specification.

[0029] The detailed description set forth below is not intended to be limiting, and the scope of the present invention should be taken to encompass the scope claimed in the claims and all scopes equivalent thereto.

[0030] Figure 1 is a drawing schematically showing a cross-section of an all-solid-state battery.

[0031] 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 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 can each be in contact with the solid electrolyte layer (13).

[0032] The positive electrode (11) and the negative electrode (12) can each be joined to the solid electrolyte layer (13) by sintering. That is, the positive electrode (11), the negative electrode (12), and the solid electrolyte layer (13) can be sintered as one body.

[0033] In Fig. 1, an all-solid-state battery (10) is illustrated as including one layer each of a positive electrode (11), a negative electrode (12), and a solid electrolyte layer (13), but the present invention is not limited thereto, and an all-solid-state battery may be configured in a form in which the positive electrode, the negative electrode, and the solid electrolyte layer are each composed of multiple layers. Alternatively, the all-solid-state battery may be configured in a form in which a positive electrode, a negative electrode, and a solid electrolyte layer are alternately laminated in multiple layers, a so-called laminated all-solid-state battery.

[0034] A 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 is composed of an oxide-based solid electrolyte, and the solid electrolyte powder according to one embodiment of the present invention can include an oxide-based powder.

[0035] As oxide-based solid electrolytes, Nasicon type such as LAGP and Garnet type such as LLZO are known, and through continuous research and development, the ionic conductivity of these oxide-based solid electrolytes has been increased to 10 -4 It is known to have improved to the S / cm level.

[0036] However, there are limits to further improving ionic conductivity with the above-mentioned NASICON-type and garnet-type oxide-based solid electrolytes. Furthermore, these oxide-based solid electrolytes are typically sintered at high temperatures, typically exceeding 1,000°C. Therefore, even if a certain degree of excellent ionic conductivity can be achieved, the increased manufacturing costs associated with high-temperature sintering cannot be avoided.

[0037] In one embodiment of the present invention, a novel oxide-based solid electrolyte is used to overcome the limitations of conventional oxide-based solid electrolytes, thereby securing excellent ionic conductivity while lowering the sintering temperature.

[0038] A solid electrolyte powder for an all-solid-state battery according to one embodiment of the present invention may include an amorphous powder and a crystalline powder. In one embodiment, the amorphous powder may include an oxide of Li, B, Al, and LiCl. In one embodiment, the crystalline powder may include at least one of a first crystalline powder including an oxide of Li, B, Al, and LiCl, and a second crystalline powder including an oxide of Li, B, and LiCl.

[0039] In this specification, a powder containing oxides of Li, B, Al and LiCl is referred to as LCBA powder, and a powder containing oxides of Li, B and LiCl is referred to as LCB powder.

[0040] In this way, the solid electrolyte powder for an all-solid-state battery according to one embodiment of the present invention comprises an amorphous powder including LCBA powder, and a crystallized powder including at least one of a first crystallized powder including LCBA powder and a second crystallized powder including LCB powder.

[0041] The LCBA powder according to one embodiment of the present invention may include Li2O, B2O3, Al2O3 and LiCl, and the LCB powder may include Li2O, B2O3 and LiCl.

[0042] In the composition of the solid electrolyte, Li2O can function as a network modifier and plays a role in improving ionic conductivity by providing Li ions.

[0043] In the composition of the solid electrolyte, B2O3 can function as a network forming agent and, as a low-temperature component, plays a role in lowering the sintering temperature.

[0044] In the composition of the solid electrolyte, Al2O3 can function as a network modifier and increase the lattice constant of the boron oxide crystal structure. Accordingly, a wider migration path for Li ions can be secured in the crystal structure, thereby improving ionic conductivity.

[0045] In the composition of the solid electrolyte, LiCl increases the amount of Li ions in the solid electrolyte, thereby improving ionic conductivity, and Cl ions enter the network structure, forming a network structure in which two types of anions coexist, thereby expanding the volume of the network structure.

[0046] Meanwhile, as described above, oxide-based solid electrolytes require simultaneous firing with the positive and negative electrodes. During this simultaneous firing process, the conductive material may oxidize or react with the positive and negative electrode materials, necessitating a lower sintering temperature. While the sintering temperature for amorphous LCBA powder can be lowered to approximately 490°C, it has been confirmed that side reactions with the positive electrode material may occur when sintered at temperatures of 490°C or higher.

[0047] In the present invention, in order to solve this side reaction problem while lowering the sintering temperature, a solid electrolyte powder is formed by including a crystalline powder in an amorphous powder.

[0048] Figure 2 is a flowchart showing a method for manufacturing a solid electrolyte for an all-solid-state battery according to one embodiment of the present invention.

[0049] According to one embodiment of the present invention, a method for manufacturing a solid electrolyte for an all-solid-state battery includes a step of manufacturing an amorphous powder (S1); a step of manufacturing a crystallized powder (S2); a step of manufacturing a mixed powder by mixing the crystallized powder with the amorphous powder (S3); and a step of sintering the mixed powder (S4).

[0050] In step (S1), a precursor powder mixed with Li2CO3, LiCl, H3BO3, and Al2O3 is pulverized and then melted, and the melt is then cooled and pulverized into fine particles to produce an LCBA amorphous powder.

[0051] According to one embodiment of the present invention, the LCBA amorphous powder may comprise 20 to 35 mol% of Li2O, 30 to 40 mol% of B2O3, 10 to 20 mol% of Al2O3, and 15 to 25 mol% of LiCl.

[0052] In step (S2), a crystallized powder is prepared. According to one embodiment of the present invention, the crystallized powder includes at least one of a first crystallized powder including LCBA powder and a second crystallized powder including LCB powder. That is, the first crystallized powder can be prepared by crystallizing the above-described LCBA amorphous powder, and the second crystallized powder can be prepared by crystallizing the LCB amorphous powder.

[0053] Here, the LCB powder is manufactured by grinding a precursor powder mixed with Li2CO3, LiCl, and H3BO3, melting it, and then cooling the melt to grind it into fine particles. According to one embodiment of the present invention, the LCB powder may include 20 to 35 mol% of Li2O, 30 to 40 mol% of B2O3, and 15 to 25 mol% of LiCl.

[0054] According to one embodiment of the present invention, each powder can be crystallized through heat treatment at a temperature of 600°C.

[0055] In step (S3), a crystallization powder is mixed into the LCBA amorphous powder. Here, the crystallization powder may include at least one of a first crystallization powder and a second crystallization powder, and the crystallization powder may function as a nucleating agent. According to one embodiment of the present invention, the crystallization powder to be used as a nucleating agent may be added to the amorphous powder in an amount of 0.5 to 5 mol%.

[0056] In step (S4), a solid electrolyte is manufactured by sintering the mixed powder. According to one embodiment of the present invention, low-temperature sintering is possible by sintering a mixed powder of amorphous powder and crystalline powder.

[0057] Figure 3 is a schematic diagram showing the action of a nucleating agent in the crystallization of an amorphous powder. With reference to this, the effects of crystallization and sintering when including a crystallizable powder are explained.

[0058] Referring to Fig. 3, when a nucleating agent is added (see the lower part of Fig. 3), the number of nucleation sites increases compared to when no nucleating agent is added (see the upper part of Fig. 3). Accordingly, when a nucleating agent is added, crystallization of the powder is promoted, and the degree of crystallinity can increase for the same heat treatment. As the degree of crystallinity increases, the solid electrolyte powder can be crystallized with less heat, thereby lowering the sintering temperature of the solid electrolyte powder.

[0059] According to one embodiment of the present invention, a pre-crystallized crystallization powder may be added to an amorphous powder of a solid electrolyte powder and used as a nucleating agent. According to this embodiment, a first crystallization powder and / or a second crystallization powder may be used as a nucleating agent. Specifically, a crystallization powder including at least one of the first crystallization powder and the second crystallization powder is added to an amorphous powder at a predetermined ratio to prepare a mixed powder, and the mixed powder is sintered to prepare a solid electrolyte for an all-solid-state battery. In one embodiment, the crystallization powder may be added to the amorphous powder at at least 0.5 wt%.

[0060] According to one embodiment of the present invention, the mixed powder including the crystallized powder of LCBA powder and / or LCA powder as a nucleating agent may preferably have a sintering temperature of 485°C or less.

[0061]

[0062] Example

[0063] LCBA amorphous 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 each precursor powder, it was placed in an Al crucible and melted at approximately 1,000°C for 30 minutes. The melt was rapidly cooled on a quenching roller, ground, and sieved to obtain fine particles having a size of 10 μm or less.

[0064] Afterwards, six types of mixed powders were manufactured by varying the type and ratio of crystallization powder added to the LCBA amorphous powder.

[0065]

[0066] Comparative example

[0067] An LCBA amorphous powder was obtained through the same process as the above example, and a comparative example was prepared in which no crystallized powder was added.

[0068]

[0069] For the solid electrolyte powders according to the above examples and comparative examples, the sintering temperature (Tx) was measured using a thermal analysis device (STD). In addition, the crystallinity, crystal size, and ratio of each crystal phase after crystallization of each mixed powder at 600°C for 3 hours were measured using an X-ray diffraction analyzer (XRD). The sintering temperature and crystallinity for each example and comparative example are summarized in Table 1.

[0070]

[0071]

[0072] In Table 1, total crystallinity refers to the percentage of crystalline matter 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.

[0073] Additionally, the crystallinity of LCBA and LCB in Table 1 indicates the crystalline ratio of each component. For example, if the crystallinity of LCBA is 75.6 and the crystallinity of LCB is 24.4, this means that 75.6% of the crystals in the entire powder are crystals of the LCBA component and 24.4% are crystals of the LCB component.

[0074] In the comparative example, the total crystallinity was 72. In contrast, the total crystallinity in Examples 1 to 6 was found to have increased to 73 to 77. In addition, as the addition ratio of the crystallized LCBA powder increased, the total crystallinity tended to increase after the 600°C heat treatment. In addition, as the addition ratio of the first crystallized powder increased, the crystal ratio of the LCBA component decreased, and the crystal ratio of the LCB component tended to increase.

[0075] In addition, it can be confirmed that the sintering temperature is lowered to less than 490°C in Examples 1 to 6. As described above, since a problem of side reactions between the solid electrolyte and the positive electrode material occurs at a sintering temperature of 490°C or higher, in the case of an example in which the sintering temperature is lowered, the problem of side reactions between the solid electrolyte and the positive electrode material of the conventional oxide solid electrolyte can be solved.

[0076] In this way, the solid electrolyte according to the present invention can not only suppress the increase in production cost 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.

[0077] Although the present invention has been described above with specific details such as specific components and limited examples, the above examples are provided only to help a more general understanding of the present invention, and the present invention is not limited thereto, and those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations based on this description.

[0078] Therefore, the idea of ​​the present invention should not be limited to the embodiments described above, and all things that are modified equally or equivalently to the claims described below as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. As a solid electrolyte powder for an all-solid-state battery, Amorphous powder containing oxides of Li, B and Al and LiCl; and A crystallized powder comprising at least one of a first crystallized powder comprising oxides of Li, B and Al and LiCl and a second crystallized powder comprising oxides of Li and B and LiCl; Including Solid electrolyte powder.

2. In paragraph 1, Containing at least 0.5 wt% of the above crystallized powder Solid electrolyte powder.

3. In paragraph 1, The above amorphous powder is, Containing 20 to 35 mol% of Li2O, 30 to 40 mol% of B2O3, 10 to 20 mol% of Al2O3 and 15 to 25 mol% of LiCl. Solid electrolyte powder.

4. In paragraph 1, The above first crystallized powder, Containing 20 to 35 mol% of Li2O, 30 to 40 mol% of B2O3, 10 to 20 mol% of Al2O3 and 15 to 25 mol% of LiCl. Solid electrolyte powder.

5. In paragraph 1, The above second crystallization powder is, Containing 20 to 35 mol% Li2O, 30 to 40 mol% B2O3 and 15 to 25 mol% LiCl Solid electrolyte powder.

6. In paragraph 1, The above amorphous powder is, Manufactured from Li2CO3, LiCl, H3BO3 and Al2O3 precursors. Solid electrolyte powder.

7. In paragraph 1, The above first crystallized powder is, Manufactured from Li2CO3, LiCl, H3BO3 and Al2O3 precursors. Solid electrolyte powder.

8. In paragraph 1, The above second crystallization powder is, Manufactured from Li2CO3, LiCl and H3BO3 precursors Solid electrolyte powder.

9. A method for manufacturing a solid electrolyte for an all-solid-state battery, A step of preparing an amorphous powder from Li2CO3, LiCl, H3BO3 and Al2O3 precursors; A step of crystallizing the amorphous powder to produce a first crystallized powder, and crystallizing the LCB powder to produce a second crystallized powder; A step of preparing a mixed powder by mixing a crystallization powder including at least one of the first crystallization powder and the second crystallization powder into the amorphous powder; and Comprising a step of sintering the above mixed powder. Method for producing a solid electrolyte for an all-solid-state battery.

Images