KR20170098199A - Solid electrolyte, method for manufacturing the same, and all solid state rechargeable lithium battery including the same - Google Patents

Abstract

The present invention relates to a solid electrolyte, a method for manufacturing the same and a lithium secondary battery including the same. The solid electrolyte has tantalum (Ta) and boron (B) doped at the same time and comprises an oxide in a Garnet structure with the high doping amount of B.

Description

TECHNICAL FIELD [0001] The present invention relates to a solid electrolyte, a method for producing the same, and a lithium secondary battery including the same. [0002]

A solid electrolyte, a process for producing the same, and a lithium secondary battery comprising the solid electrolyte.

Lithium-ion batteries have a higher energy density per unit volume than those of other battery systems, and are widely used in electronic devices and the like, and have been widely used in automobiles and energy storage devices.

However, since a known lithium ion battery basically uses a liquid electrolyte, a problem of safety related to explosion or ignition is constantly generated.

As a substitute for such a liquid electrolyte, there has been proposed a solid electrolyte classified into three types, namely, a sulfide system, a polymer system, and an oxide system. However, the sulfide-based solid electrolyte has a high reactivity with atmospheric and / or oxide-based cathode active materials such as LiCoO ₂ , and thus is difficult to handle as such. In the case of a polymer-based solid electrolyte, thermal stability is poor, And in the case of an oxide-based solid electrolyte, there is a problem that it exhibits a relatively low ionic conductivity of 10 ^-6 to 10 ^-5 S / cm.

In addition, in particular, in the case of an oxide-based solid electrolyte, it is common to mix and sinter with an anode and apply it to a lithium ion battery. However, since the sintering temperature is high, lithium (Li) A reaction is induced at each interface or a difference in thermal expansion coefficient between the respective materials causes a problem such as desorption.

Therefore, in order to commercialize a middle- or large-sized lithium ion battery, solving the safety problem of a liquid electrolyte by using a solid electrolyte, overcoming the disadvantages of a generally known solid electrolyte with high reactivity or low ion conductivity, It is necessary to lower the sintering temperature.

The solid electrolyte provided in one embodiment of the present invention is one in which tantalum (Ta) and boron (B) are simultaneously doped, and includes an oxide of Garnet structure having a high doping amount of boron. .

In another embodiment and another embodiment of the present invention, a method for producing the solid electrolyte and a lithium secondary battery including the solid electrolyte are provided.

Solid electrolyte

In one embodiment of the present invention, a solid electrolyte including an oxide of Garnet structure doped with boron (B) and tantalum (Ta), wherein the molar ratio of boron (B) to the solid electrolyte is 0.1 or more.

In this connection, the molar ratio of the tantalum (Ta) to the boron (B) may be 0.35 / 0.1 to 0.35 / 0.4.

On the other hand, the oxide of the garnet structure may be doped with aluminum (Al). In this case, the molar ratio of the aluminum (Al) to the boron (B) may be 0.5 / 0.1 to 0.1 / 0.4.

Specifically, the solid electrolyte may be represented by the following general formula (1).

Li _(7-ax) M ¹ _x La ₃ Zr _{2 -yw} Ta _y B _z M ² _w O ₁₂

Wherein M ¹ is selected from the group consisting of Al, Na, K, Rb, Cs, Fr, Mg, Ca and combinations thereof; M ² is selected from the group consisting of Nb, Sb, Sn, Hf, Bi, W , Se, Ga, Ge, and combinations thereof, and 0? A? 0.1, 0? X? 0.5, 0.005? Y? 0.5, 0.1? Z? 0.5, 0.15.)

More specifically, in Formula 1, M ¹ may be Al.

In the above formula (1), 0.1? Z? 0.4.

Independently, in the above formula (1), 0? X? 0.3.

The crystal structure of the solid electrolyte may be a cubic structure.

The ionic conductivity of the solid electrolyte may be 0.9 x 10 ^-4 S / cm or more.

Method for producing solid electrolyte

In another embodiment of the present invention, there is provided a method for producing a mixed powder, comprising the steps of: preparing a mixed powder comprising a lithium raw material, a lanthanum raw material, a zirconium raw material, a tantalum raw material, and a boron raw material; Pulverizing the mixed powder; And calcining the pulverized mixed powder to obtain a powdery solid electrolyte, wherein the solid electrolyte obtained is a garnet (G) doped with boron (B) and tantalum (Ta) Wherein the molar ratio of the boron (B) to the solid electrolyte is 0.1 or more, and the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material Preparing a mixed powder comprising the steps of: charging each of the raw materials at a molar ratio corresponding to the molar amount of lithium, lanthanum, zirconium, and tantalum in the obtained solid electrolyte, By weight, based on the total weight of the solid electrolyte.

Specifically, in the step of preparing a mixed powder comprising the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material,

And the molar ratio of tantalum to boron in the mixed powder is 0.35 / 0.1 to 0.35 / 0.4.

The mixed powder may further include an aluminum raw material, a sodium raw material, a potassium raw material, a rubidium raw material, a cesium raw material, a franc raw material, a magnesium raw material, a calcium raw material, or a combination thereof .

More specifically, the mixed powder may further comprise an aluminum raw material. In this case, the molar ratio of aluminum to boron in the mixed powder may be 0.5 / 0.1 to 0.1 / 0.4.

On the other hand, the step of preparing the mixed powder including the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material may be a step of mixing lithium, lanthanum, zirconium, Adding the respective raw materials at a molar ratio corresponding to the molar amount of the raw materials, and mixing the raw materials; Thereafter, the lithium primary material may be further added to the primary mixed material and the secondary mixed material may be mixed.

Specifically, in the step of additionally adding and mixing lithium raw material to the primary mixed material, the amount of the lithium raw material to be added is preferably 1 to 10 times the lithium raw material in the primary mixed material To 5 mol%.

On the other hand, calcining the pulverized mixed powder to obtain a powdery solid electrolyte; Thereafter, the solid electrolyte obtained is formed into a pellet; And sintering the formed pellets.

Specifically, sintering the formed pellets may be performed at a temperature ranging from 850 to 950 ° C.

Independently, the step of sintering the formed pellets may be performed for 7 to 20 hours.

The step of pulverizing the mixed powder may be a ball mill, a mortar, a sieve, an attrition mill, a disk mill, a jet mill, ), A jaw crusher, a crusher, or a combination thereof.

Lithium secondary battery

In another embodiment of the present invention, cathode; Wherein the solid electrolyte is a solid electrolyte including an oxide of Garnet structure doped with boron (B) and tantalum (Ta), the boron (B) to the solid electrolyte, Is 0.1 or more.

The solid electrolyte provided in one embodiment of the present invention includes an oxide of a Garnet structure doped with tantalum (Ta) and boron (B), and particularly, a boron (B) capable of liquid phase sintering ) Is high, and high ion conductivity and excellent sintering property can be secured even at a low temperature.

The method for producing a solid electrolyte according to another embodiment of the present invention has an advantage that a solid electrolyte having excellent properties can be mass-produced by a simple process.

The lithium secondary battery according to another embodiment of the present invention can improve its electrochemical performance by including the solid electrolyte having the excellent characteristics.

1 is a graph showing the total ion conductivity with respect to the solid electrolyte produced according to Production Example 1 of the present invention.
2 shows a Nyquist plot with respect to the solid electrolyte produced according to Production Example 1 of the present invention.
FIG. 3 shows an x-ray diffraction (XRD) pattern with respect to the solid electrolyte produced according to Preparation Example 1 of the present invention.
4 to 9 show distribution diagrams of the respective elements with respect to the solid electrolyte produced according to Production Example 1 of the present invention.
10 shows a Nyquist plot with respect to the solid electrolyte produced according to Production Example 2 of the present invention.
11 to 14 are scanning electron microscopy (SEM) photographs of each solid electrolyte produced according to Production Examples 3 and 1 of the present invention.
15 to 22 show distribution diagrams of the respective elements with respect to the solid electrolyte produced according to Production Example 3 of the present invention.
Fig. 23 shows the potential window of the solid electrolyte produced according to Production Example 3 of the present invention. Fig.
FIG. 24 shows a 10th charge / discharge graph of a battery including the solid electrolyte produced according to Production Example 3 of the present invention.
FIG. 25 is a graph showing the life-time characteristics of the battery including the solid electrolyte produced according to Production Example 3 of the present invention at 10 times of charge / discharge cycle.
26 is a graph showing the charging / discharging characteristics of the all-solid-state battery including the solid electrolyte produced according to Production Example 3 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

Solid electrolyte

In one embodiment of the present invention, a solid electrolyte including an oxide of Garnet structure doped with boron (B) and tantalum (Ta), wherein the molar ratio of boron (B) to the solid electrolyte is 0.1 or more.

This is because it contains an oxide of garnet structure doped with tantalum (Ta) and boron (B), and particularly the doping amount of boron (B) which enables liquid phase sintering is high, And is a solid electrolyte capable of ensuring sintering properties.

Generally, the garnet structure oxide is relatively wide in potential window, low in water reactivity, less reactive with metallic lithium, and suitable for use as a solid electrolyte replacing liquid electrolyte.

On the other hand, the crystal structure of the garnet structure oxide is classified into tetragonal and cubic structures. Among them, the cubic structure having high disordering of lithium (Li) has ion conductivity Is about 10 to 100 times higher.

However, for the basic composition (Li ₇ La ₃ Zr ₂ O ₁₂ ) of the Garnet structure, it is necessary to synthesize phases at a high temperature of 1,230 ° C. or more in order to produce the cubic system structure from the tetragonal structure.

However, due to the high sintering temperature, lithium (Li) evaporates at the anode when the lithium secondary battery is manufactured in the form of a pre-solid battery (i.e., the structure of the anode / solid electrolyte / cathode) Reaction occurs, or the material is separated due to a difference in thermal expansion coefficient between the respective materials.

As described later, the solid electrolyte may include an oxide having a cubic system structure among the garnet structure. However, the doping amount of the boron (B) is high, while the ion conductivity is increased by the doping of the decarburization (Ta) The temperature can be lowered and the sintering property can be improved.

Specifically, in the case of tantalum (Ta), there is no reactivity with lithium (Li) in a small amount of doping, but since the content of lithium (Li) is reduced by substituting zirconium (Zr) , The content of lithium (Li) can be reduced. This can contribute to improving the ion conductivity by increasing the vacancy of lithium (Li). Niobium (Nb) may also play a role similar to tantalum (Ta), but tantalum (Ta) is less reactive with lithium.

However, when the tantalum (Ta) alone is doped, the cubic system structure can be stably formed, but it is confirmed that it is difficult to lower the sintering temperature to 1,000 ° C. or less. It is supported by examples.

On the other hand, in the case of boron (B), as described above, liquid phase sintering is possible and the doping element makes the oxide structure of the cubic system structure dense in the garnet structure.

With reference to the above description, the solid electrolyte provided in one embodiment of the present invention will be described in detail.

1. The solid electrolyte includes an oxide of a garnet structure in which tantalum (Ta) and boron (B) are simultaneously doped and boron (B) has a high doping amount.

Specifically, the molar ratio of tantalum (Ta) to boron (B) in the garnet structure oxide contained in the solid electrolyte may be 0.35 / 0.1-0.35 / 0.4, that is, the doping amount of tantalum (Ta) When molar, the doping amount of boron (B) may be 0.1 to 0.4 mol.

As described above, when boron (B) is doped at a high rate of 0.1 mol to 0.4 mol to an oxide of garnet structure which is basically doped with 0.35 mol of tantalum (Ta) to ensure high ion conductivity, the above-described liquid phase sintering is possible Whereby the sintering temperature of the solid electrolyte can be lowered to 1,000 ° C or lower.

Particularly, when the molar ratio is appropriately controlled, as described in the following examples and evaluation examples thereof, the solid electrolyte (e.g., LiCoO ₂ ) can be co-sintered with the cathode active material The sintering temperature can be lowered.

Further, as the doping amount of boron (B) increases within the above-mentioned limited range, the phase of the solid electrolyte is stabilized and the sintering property can be improved.

2. Further, the oxide of the garnet structure included in the solid electrolyte may be further doped with aluminum (Al).

Specifically, in the garnet structure oxide contained in the solid electrolyte, the molar ratio of aluminum (Al) to boron (B) may be 0.5 / 0.1-0.1 / 0.4. That is, when the doping amount of boron (B) is 0.1 to 0.4 mole, the doping amount of aluminum (Al) may be 0.1 to 0.5 mole. When the solid electrolyte in this case is formed into pellets, the pores are reduced and the density is improved.

3. As will be described later, the solid electrolyte may be prepared by excessively adding a lithium raw material to the target composition.

The lithium source material added in such an excess amount forms a lithium borate by being partially bound to boron, and the lithium borate is distributed between the solid electrolyte particles and the particles to bridge the bridge of lithium ), And can ultimately contribute to improving the ionic conductivity and pellet density of the solid electrolyte.

Regarding the above-mentioned contents, the solid electrolyte may be represented by the following general formula (1).

Li _(7-ax) M ¹ _x La ₃ Zr _{2 -yw} Ta _y B _z M ² _w O ₁₂

Wherein M ¹ is selected from the group consisting of Al, Na, K, Rb, Cs, Fr, Mg, Ca and combinations thereof; M ² is selected from the group consisting of Nb, Sb, Sn, Hf, Bi, W , Se, Ga, Ge, and combinations thereof, and 0? A? 0.1, 0? X? 0.5, 0.005? Y? 0.5, 0.1? Z? 0.5, 0.15.)

In the above formula (1), 0.1? Z? 0.4, which means the doping amount of boron (B) described above.

In the above formula (1), M ¹ may be Al, which means the additional doping of aluminum as described above.

In the above formula (1), 0? X? 0.3, which relates to a lithium raw material added in an excess amount as described above.

On the other hand, the solid electrolyte may have a cubic structure and is more advantageous in improving the ion conductivity than the tetragonal structure as described above.

Further, although it is generally necessary to synthesize a phase at a high temperature of 1,230 ° C. or more to form a cubic system structure, the solid electrolyte can be sintered at a temperature lower than 1,000 ° C. to form a stable phase.

The ionic conductivity of the solid electrolyte may be 0.9 x 10 ^-4 S / cm or more. This is an ion conductivity exhibiting excellent durability due to the fact that tantalum (Ta) and boron (B) are simultaneously doped and contain an oxide of garnet structure with a high doping amount of boron (B).

Specifically, the ionic conductivity may be 0.95 x 10 ^-4 S / cm or more in accordance with the control of the amount of boron (B) doping and / or the control of the amount of lithium source material added excessively in the production of the solid electrolyte.

Method for producing solid electrolyte

In another embodiment of the present invention, there is provided a method for producing a mixed powder, comprising the steps of: preparing a mixed powder comprising a lithium raw material, a lanthanum raw material, a zirconium raw material, a tantalum raw material, and a boron raw material; Pulverizing the mixed powder; And calcining the pulverized mixed powder to obtain a powdery solid electrolyte, wherein the solid electrolyte obtained is a garnet (G) doped with boron (B) and tantalum (Ta) Wherein the molar ratio of the boron (B) to the solid electrolyte is 0.1 or more, and the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material Preparing a mixed powder comprising the steps of: charging each of the raw materials at a molar ratio corresponding to the molar amount of lithium, lanthanum, zirconium, and tantalum in the obtained solid electrolyte, By weight, based on the total weight of the solid electrolyte.

This is equivalent to the method of producing the solid electrolyte described above. The raw materials are mixed in an amount equal to the molar amount of each element in the final solid electrolyte to be obtained, and the thus mixed powder is pulverized and fired, And a series of steps of obtaining an electrolyte.

Hereinafter, the above-described steps will be described in detail, omitting duplicate descriptions.

1. Specifically, in the step of preparing a mixed powder comprising the lithium source material, the lanthanum source material, the zirconium source material, the tantalum raw material, and the boron source material, the molar ratio of tantalum to boron in the mixed powder is 0.35 / 0.1 to 0.35 / 0.4.

In this case, a solid electrolyte satisfying the above-mentioned molar ratio range can be finally obtained.

2. On the other hand, the step of preparing a mixed powder comprising the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material is a step of mixing lithium, lanthanum, zirconium, And molar ratios corresponding to molar amounts of tantalum; Thereafter, the lithium primary material may be further added to the primary mixed material and the secondary mixed material may be mixed.

This corresponds to a process of charging excess lithium raw material in preparation for the target composition.

Specifically, in the step of additionally adding and mixing lithium raw material to the primary mixed material, the amount of the lithium raw material to be added is preferably 1 to 10 times the lithium raw material in the primary mixed material To 5 mol%.

Some of the excess is volatilized during sintering of the final solid electrolyte while the other part is combined with boron and the remaining part is combined with carbon dioxide (CO ₂ ) in the atmosphere to form lithium-boron-carbon oxide, lithium borate lithium borate, and lithium carbonate, and the materials thus formed may be present between the solid electrolyte particles and the particles.

In particular, the lithium borate is distributed between the solid electrolyte particles and the particles during the sintering of the final solid electrolyte to mediate the movement of lithium ions and can contribute to the improvement of the pellet density.

3. On the other hand, the mixed powder may further comprise at least one of aluminum raw material, sodium raw material, potassium raw material, rubidium raw material, cesium raw material, francium raw material, magnesium raw material, calcium raw material, .

More specifically, the mixed powder may further include an aluminum raw material, for doping aluminum (Al) together with tantalum (Ta) and boron (B).

In this case, the molar ratio of aluminum to boron in the mixed powder may be in the range of 0.5 / 0.1 to 0.1 / 0.4. When the molar ratio satisfies the molar ratio, the solid electrolyte satisfying the molar ratio is obtained .

On the other hand, calcining the pulverized mixed powder to obtain a powdery solid electrolyte; Thereafter, the solid electrolyte obtained is formed into a pellet; And sintering the formed pellets.

This corresponds to the step of molding the solid electrolyte in a form suitable for application to all solid batteries.

Specifically, the step of sintering the formed pellets may be performed at a temperature of less than 1,000 ° C, more specifically, 850 to 950 ° C. This is very low compared to the sintering temperature of a generally known solid electrolyte due to the high boron (B) doping amount. A detailed explanation related to this is as described above.

Independently, the step of sintering the formed pellets may be performed for 7 to 20 hours. If this is carried out for less than 7 hours, the pellets can not be sufficiently sintered and the pellet density becomes low. However, it is not economical to perform over 20 hours.

In addition, sintering the formed pellets may be performed in an oxygen (O ₂ ) atmosphere. In this case, excellent electrical conductivity can be secured as compared with the case of performing in an atmospheric environment, because oxygen is supplied so that the reaction can sufficiently take place even when the sintering temperature is low.

The step of pulverizing the mixed powder may be a ball mill, a mortar, a sieve, an attrition mill, a disk mill, a jet mill, ), A jaw crusher, a crusher, or a combination thereof.

Lithium secondary battery

In another embodiment of the present invention, cathode; Wherein the solid electrolyte is a solid electrolyte including an oxide of Garnet structure doped with boron (B) and tantalum (Ta), the boron (B) to the solid electrolyte, Is 0.1 or more.

Specifically, the solid electrolyte may be one according to any one of those described above. In this case, the lithium secondary battery may exhibit excellent charge / discharge characteristics and life characteristics.

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the present invention is not limited to the following examples.

Specifically, the doping amount of boron (B) was measured in the same manner as in Production Example 1, _{except that} an oxide (Li _6.65 La ₃ Zr _1.65 Ta _0.35 O ₁₂ ) having a Garnet structure doped with 0.35 mol of decarburization (Ta) The effect according to the control is first confirmed, and the optimum range is derived.

On the basis of the results, the respective effects of controlling the amount of lithium raw material to be added in an excessive amount in the mixing step of the raw material (Production Example 2) and further doping (Production Example 3) of aluminum (Al) are confirmed.

Production Example 1

(1) Synthesis of solid electrolyte

As previously mentioned, but the composition of the tantalum oxide powder (Ta) is a garnet (Garnet) doped structure _{0.35mol (Li 6. 65 La 3} Zr 1. 65 Ta 0. 35 O 12) as a basic composition, the boron (B).

As a raw material therefor, LiOH · H ₂ O powder (Alfa Aesar, 99.995%), La 2 O 3 powder (Kanto, 99.99%), ZrO 2 powder (Kanto, 99%), Ta 2 O 5 powder (Aldrich, 99%), and H ₃ BO ₃ Powder (Aldrich, 99.9%) were prepared.

Among the raw materials, La ₂ O ₃ powder, ZrO ₂ The powder, Ta ₂ O ₅ powder, and H ₃ BO ₃ (Aldrich, 99.9%) were mixed with the desired Li _{6 . 65} La ₃ Zr _{1 . 65} Ta _{0 .} Were each weighed to meet the molar ratio of ₃₅ B _(x) O ₁₂ (x = 0, 0.02, 0.05, 0.1, 0.2, 0.3, or 0.4). At this time, with respect to the x value indicating the doping amount of the boron (B), it is decided whether or not the embodiment or the comparative example is to be made in the evaluation example 1 to be described later.

On the other hand, in the case of LiOH.H ₂ O powder as a raw material of lithium, in consideration of the volatilization of lithium at the time of pellet sintering in the future, 5 mol% excess relative to the target composition was prepared.

Prior to mixing the raw materials, the La ₂ O ₃ was dried at 900 ° C. for 24 hours to remove any adsorbed water. The LiOHH ₂ O powder It was also dried at 200 ° C for 6 hours to remove water adsorbed on the surface.

ZrO ₂ , Ta ₂ O ₅ , and H ₃ BO ₃ were mixed together with the dried La ₂ O ₃ and LiOH · H ₂ O, and mixed with zirconia (Zirconia) having a diameter of 3 mm and a diameter of 5 mm at a ratio of 1: 1 After loading in a Nalgene bottle with ball, anhydrous IPA was added and ball milled at 25 ° C for 24 hours. At this time, in order to improve the mixing performance, a small amount (about 1% by weight with respect to the total weight of the mixed powder) of 28% ammonia water as a dispersant was added.

The ball milled powder was dried in a drying furnace at 200 ° C for 24 hours and then calcined in a sintering furnace at 900 ° C for 7 hours. The rate of temperature increase at this time was 2 ° C / min. The fired powder was ball-milled at 25 DEG C for 12 hours to obtain a uniform powder having an average particle diameter of 2 mu m or less A solid electrolyte powder was obtained.

Specifically, the solid electrolyte powder finally obtained in Production Example 1 satisfied the composition of Li _6.65 La ₃ Zr _1.65 Ta _0.35 B _(x) O ₁₂ (x = 0, 0.02, 0.05, 0.1, 0.2, 0.3 or 0.4) Is an oxide powder of garnet structure.

 (2) Pellets  Preparation of sintered body

The solid electrolyte of Preparation Example 1, the _{(Li 6. 65 La 3 Zr} 1. 65 Ta 0. 35 B (x) O 12, x = 0, 0.02, 0.05, 0.07, 0.1, 0.2, 0.3, or _0.4) powders each Dried and then formed into a pellet by applying a pressure of ² ton / cm ² with a forming mold, followed by sintering in an oxygen atmosphere for 14 hours.

At this time, the sintering temperature was set to 2 ° C / min, and the final sintering temperature was controlled to 850, 900, 950, 1000, or 1,050 ° C to obtain respective sintered bodies.

Evaluation Example 1: Evaluation concerning Production Example 1

(One) Evaluation of total ion conductivity by doping amount of boron and sintering temperature

A pellet sintered body of Production Example 1 (Li _6.65 La ₃ Zr _1.65 Ta _0.35 B _(x) O ₁₂ , x = 0, 0.02, 0.05, 0.07, 0.1, 0.2, 0.3 or 0.4 ₎ The total ion conductivity was measured, and the results are shown in Fig.

Referring to FIG. 1, at a high sintering temperature of 1,000 ° C. or higher, the total ion conductivity is maintained in a high range of 3 × 10 ^-4 to 6 × 10 ^-4 S / cm regardless of the doping amount of boron .

However, in order to commercialize all solid-state batteries, it is necessary to lower the sintering temperature of the solid electrolyte to such a degree that co-sintering with a cathode active material (for example, LiCoO ₂ ) It is necessary to evaluate the total ionic conductivity appearing at the temperature.

Specifically, at a sintering temperature of 950 ° C. or lower, it can be seen that the value of the total ionic conductivity drastically changes with the boron doping amount of 0.1 mol as a boundary. More specifically, when there is no doping amount of boron or less than 0.1 mol, the total ion conductivity shows a low value in the range of -10 ^-6 to -10 ^-7 S / cm.

On the other hand, when the doping amount of boron is 0.1 mol, the total ionic conductivity of the solid electrolyte rapidly rises to a high value, and the total ion conductivity thus increased is maintained steadily in the range of 0.1 mol to less than 0.4 mol of the boron doping amount Can be confirmed.

Accordingly, at a sintering temperature of 950 ° C. or lower, it can be estimated that the doping amount of boron has a significant influence on the total ion conductivity of the solid electrolyte. Specifically, when the doping amount of boron (B) is 0.1 mol or more and 0.4 mol or less among the solid electrolytes synthesized in Production Example 1, the doping amount of the example, boron (B) is less or less than 0.1 mol, it can be evaluated as a comparative example.

Further, when the doping amount of boron (B) is 0.3 mol, the total ionic conductivity is 1.1 x 10 ^-4 S / cm even at a very low sintering temperature of 850 ° C, which means that the cathode active material (for example, LiCoO ₂ ) And a low-temperature sinterable solid electrolyte capable of co-sintering.

(2) Depending on the sintering temperature Total ionic conductivity evaluation

More specifically, for each pellet sintered body obtained by varying the doping amount of boron (B) in the solid electrolyte of Production Example 1 to 0.3 mol, the sintering temperature was varied to 850, 900, 950, or 1000 ° C, AC impedance) were measured. 2 corresponds to a polar coordinate plot (Nyquist plot) according to the measurement of the AC resistance.

Specifically, at the time of the AC resistance measurement, gold (Au) was deposited at 300 nm on both surfaces of each pellet sintered body to be measured. The initial vacuum degree was 5 × 10 ^-6 torr or less and the gold target was 3 inches. The pre-sputtering before deposition was performed at a rate of 10 Min. Also, for uniform deposition, the substrate was rotated at 100 rpm, the deposition rate was 20 nm / min, and argon (Ar) was used as the process gas.

Each of the pellet sintered bodies on which gold (Au) was deposited on both sides was connected to an AC impedance analyzer (BioLogic) using a Teflon jig, and the measurement frequency was changed from 7 MHz to 1 Hz To obtain a Nyquist plot.

Typically, the total resistance of a solid electrolyte made of a crystalline phase is calculated as the sum of the grain boundary resistance and the grain interior resistance. In the Nyquist plot, two semicircles appear. The semicircle in the high frequency region is denoted by the grain interior resistance, and the semicircle in the low frequency region is denoted by the grain boundary resistance. Thereby analyzing each graph in Fig.

Specifically, in FIG. 2, as the sintering temperature increases, the grain interior resistance and the grain interior resistance tend to increase, but the increase range is not large. A high ionic conductivity of ~ 10 ^-4 S / cm was measured at all temperature ranges from 850 to 1,000 ° C. The doping of boron (B) improved the total ion conductivity of the solid electrolyte at low sintering temperatures You can check your contributions once again.

(3) Evaluation of stability of phase according to doping amount of boron (B)

The sintering temperature for the solid electrolyte of Production Example 1 was kept constant at a low temperature of 850 DEG C, and the doping amount of boron was varied to 0.07, 0.1, 0.2, 0.3, or 0.4 mol, and x-ray diffraction x -ray diffraction (XRD) pattern, and the result is shown in FIG.

As described above, the possible crystal structures of garnet-like oxides include a tetragonal crystal structure and a cubic crystal structure. Generally, in the analysis of the XRD graph, 16 °, 25 °, Peak split in the 31 °, 34 °, and 52 ° regions is estimated to be exhibited by a typical tetragonal crystal structure.

3, when the doping amount of boron is 0.07 mol, the peak split phenomenon appears slightly in the above region. However, the above phenomenon gradually disappears as the boron doping amount increases to more than 0.1 mol, It is confirmed that the above phenomenon hardly occurs.

That is, as the doping amount of boron (B) increases, the cubic crystal structure is stabilized at a low sintering temperature.

(4) Evaluation of elemental distribution

The sintered pellet having a sintering temperature of 950 DEG C was selected to obtain more definite results in the case where the doping amount of boron in the solid electrolyte of Production Example 1 was 0.3 mol, and the distribution of each element contained in the pellet sintered body was shown in Figs. 9.

Specifically, the sintered body was processed using a focused ion beam (FIB), and the processed cross section was scanned using an electron probe micro-analyzer (EPMA). As a result, 4 to 9 were obtained. Specifically, FIG. 4 is a bright field image, and FIGS. 5 to 8 are images for each element.

4 to 9, tantalum (Ta), which is a doping element as well as lanthanum (La), zirconium (Zr), and oxygen (O) as main elements is uniformly distributed in solid electrolyte particles constituting the sintered body (Figs. 4 to 7).

However, in the case of boron (B) which is another doping element (FIG. 9), it is confirmed that not only the inside of the solid electrolyte particle constituting the sintered body but also the same position between carbon and the solid electrolyte particle (Fig. 8).

These results indicate that, when mixing the raw materials in Production Example 1, the excess amount of lithium raw material (i.e., LiOH.H ₂ O Powder).

Particularly, some of the excess is volatilized during sintering, while the other part is bonded to boron and the remaining part is bonded to carbon dioxide (CO ₂ ) in the atmosphere to form lithium-boron-carbon oxide, lithium borate lithium borate, and lithium carbonate, and it is understood that the materials thus formed are present between the solid electrolyte particles and the particles.

Particularly, the lithium borate includes lithium and boron, and is expected to serve as a bridge for mediating movement of lithium between the solid electrolyte particles and the particles.

Thus, boron (B) is not only a doping element in the solid electrolyte, but also acts as a glue layer for connecting the solid electrolyte particles to the particles during sintering of pellets or as a bridge for mediating the movement of lithium .

Production Example 2

(1) Synthesis of solid electrolyte

Unlike Production Example 1, the amount of boron doped was changed, but the amount of lithium raw material added in excess was changed when the raw material was mixed.

Specifically, La ₂ O ₃ powder, ZrO ₂ The powder, Ta ₂ O ₅ powder and H ₃ BO ₃ powder were weighed to be in a molar ratio of Li _6.65 La ₃ Zr _1.65 Ta _0.35 B _(x) O ₁₂ (x = 0.1) H ₂ O The powders were prepared and mixed in excess of 1, 3, and 5 mol%, respectively, relative to the target composition.

That is, in the production example 2, the reference for blending each of the raw materials mentioned above corresponds to the molar ratio of Li _x La ₃ Zr _1.65 Ta _0.35 B _0.1 O ₁₂ (x = 6.72, 6.85, or 6.98).

The remaining process was the same as Production Example 1, and each solid electrolyte powder of Production Example 2 was obtained.

(2) Preparation of pellet sintered body

Each of the solid electrolyte powders of Preparation Example 2 was subjected to the same conditions as in Production Example 1, except that sintering temperature was all set to 950 캜, thereby producing respective pellet sintered bodies.

Evaluation Example 2: Evaluation concerning Production Example 2

(1) Assessment of total ionic conductivity with excess lithium source material

For each pellet sintered body of Production Example 2, a Nyquist plot of Fig. 10 was obtained in the same manner as in (2) of Evaluation Example 1.

According to FIG. 10, it can be seen that the size of the semi circle is drastically reduced in the case of 3 mol% and 5 mol%, respectively, as compared with the case where the amount of the lithium raw material added in excess to the target composition is 1 mol% .

(2) Evaluation of total ionic conductivity , pellet density , and activation energy for excess lithium input materials

Further, the total ionic conductivity (? _Total ) was determined based on the size of the semicircle obtained from the Nyquist plot of FIG. 10, and the pellet density and the activation energy of each pellet were measured and shown in Table 1 below.

Specifically, the total ion conductivity (sigma _total ) in the following Table 1 is calculated by calculating the total resistance of the solid electrolyte as the sum of the grain boundary resistance and the grain interior resistance, Is calculated by substituting into the following equation (1).

[Equation 1]? _Total = (1 /? _Total ) x (L / A)

(σ _total = total ion conductivity, Ω _total = total resistance = grain boundary resistance and sum of grain interior resistance, L = thickness of pellet, A = area of pellet)

Amount of lithium raw material added excessively to target composition
(Amount of Li Excess) Total ion conductivity
(Total Ionic Conductivity, 298.15K) Pellet density
(Pellet Density) Activation energy
(Ea) 1 mol% 3.89 x 10 ^-5 S / cm 2.89 g / cm < ³ > 0.48 eV 3 mol% 8.16 x 10 ^-5 S / cm 3.46 g / cm < ³ > 0.45 eV 5 mol% 2.80 x 10 ^-4 S / cm 4.18 g / cm < ³ > 0.47 eV

According to Table 1, the total ionic conductivity increased to 2.8 x 10 ^-4 S / cm and the pellet density increased to 4.18 g / cm ³ as the amount of lithium raw material added in excess of the target composition increased Is confirmed.

These results are inferred from the results of (4) in Evaluation Example 1, that is, a part of the lithium source material added in excess to the target composition binds to boron to form lithium borate between the electrolyte particles and the particles The pellet density can be increased.

In general, the activation energy is understood as a measure of the change in ionic conductivity with temperature, which can be obtained from log (σT) and slope of 1000 / T (σ: total ion conductivity, T: absolute temperature; K) .

In the case of the solid electrolyte, the lower the activation energy, the lower the dependency on the temperature. Thus, the solid electrolyte exhibits good characteristics as a solid electrolyte. In Table 1, although the amount of the lithium raw material used in Production Example 2 is increased, It is confirmed that the value is not largely changed. That is, even if the amount of the lithium raw material used in Production Example 2 is increased, it can be estimated that the activation energy is not lowered.

Production Example 3

Unlike Production Example 1, an additional aluminum raw material was added.

Specifically, La ₂ O ₃ powder, ZrO ₂ Powder, Ta ₂ O ₅ powder, and H ₃ BO ₃ The powder was weighed to be in a molar ratio of Li _6.65 La ₃ Zr _1.65 Ta _0.35 B _(x) O ₁₂ (x = 0.3), and the lithium raw material LiOHH ₂ O The powder was prepared in excess of 5 mol% in comparison with the above-mentioned composition in the same manner as in Preparation Example 1.

Then, an additional amount of γ-Al ₂ O ₃ powder (Aldrich, 99.9%) as an aluminum raw material was added, and the amount of the addition was determined such that 0.2 mol of aluminum (Al) was further doped to the target composition.

The remaining process was the same as Production Example 1, and each solid electrolyte powder of Production Example 3 was obtained.

(2) Preparation of pellet sintered body

For each solid electrolyte powder of Production Example 3, sintering temperatures were controlled to 850, 900, 950, or 1000 ° C in various manners, and the other pellet sintered bodies were produced under the same conditions as in Production Example 1.

Evaluation Example 3: Comparative Evaluation of Production Examples 1 and 3

Each of the pellet sintered bodies of Production Example 3 was obtained in the same manner as in Production Example 1 except that Li _{6 . 65} La ₃ Zr _{1 . 65} Ta _{0 . 35} B (x) O ₁₂ (x = 0.3).

(1) Evaluation of total ion conductivity , pellet density, and activation energy by doping with aluminum (Al)

Specifically, for each of the sintered bodies, the total ion conductivity (? _Total ) was determined in the same manner as in Evaluation Example 2, and the pellet densities and activation energies of the respective sintered bodies were measured and shown in Table 2 below.

In Table 2 below, those marked with Al = 0 relate to 1 in the preparation and those marked with Al = 0.2 relate to Preparation Example 3.

Sintering temperature
(Sintering Temp.) Total ion conductivity
(Total Ionic Conductivity,
298.15K) Pellet density
(Pellet Density) Activation energy
(Ea) Al = 0 850 ℃ 1.09 x 10 ^-4 S / cm 2.83 0.48 900 ℃ 1.64 x 10 ^-4 S / cm 3.34 0.46 950 ℃ 2.59 x 10 ^-4 S / cm 3.64 0.49 1,000 ℃ 6.43 x 10 ^-4 S / cm 4.72 0.38 Al = 0.2 850 ℃ 9.81 x 10 ^-5 S / cm 3.23 0.46 900 ℃ 3.34 x 10 ^-4 S / cm 4.00 0.43 950 ℃ 3.53 x 10 ^-4 S / cm 4.60 0.42 1,000 ℃ 2.77 x 10 ^-4 S / cm 4.39 0.36

Referring to Table 2, the ionic conductivity of Preparation Example 3 doped with 0.2 mol of aluminum (Al) was similar to that of Preparation Example 1, but the pellet density was greatly improved.

On the other hand, in Table 2, the activation energy (Ea) does not differ greatly depending on whether or not the aluminum (Al) is further doped, except in the case of sintering at a high temperature of 1,000 ° C.

(2) Evaluation of pore characteristics of pellets by further doping with aluminum (Al)

Sintering electron microscopy (SEM) photographs of the cut surfaces of the pellet sintered bodies of Production Example 3 and Production Example 1, which were the evaluation targets of Evaluation Example 3, at sintering temperatures of 900 and 950 ° C, Respectively.

Specifically, FIG. 11 (sintering temperature: 900 DEG C) and FIG. 12 (sintering temperature: 950 DEG C) Production Example 3 ".

Referring to FIGS. 11 to 14, it is confirmed that pores are reduced in Production Example 3 in which 0.2 mol of aluminum (Al) is further doped, regardless of sintering temperature, as compared to Production Example 1. As a result, aluminum doped further in Production Example 3 was found to have an effect of reducing the pores in the pellets, thereby contributing to improvement of the pellet density.

(3) Evaluation of elemental distribution

The sintered pellets of Production Example 3 (sintering temperature: 950 deg. C) were shown in FIG. 15 to FIG. 22 for distribution of each element contained in the pellet sintered body in the same manner as in (4) of Evaluation Example 1.

15 to 22, lanthanum (La), zirconium (Zr), oxygen (O), and tantalum (Ta) are uniformly distributed in solid electrolyte particles constituting the sintered body, (C) shows the same distribution at the positions between the particles and the particles (Figs. 15 to 21).

These results indicate that the evaluation results confirmed in (4) of Evaluation Example 1, that is, not only the boron (B) is a doping element in the solid electrolyte, but also an adhesive layer for connecting the solid electrolyte particles to the particles layer or a bridge that mediates the movement of lithium.

On the other hand, in the case of aluminum (Al), it is deduced that it helps the functions of boron (B) and carbon (C), specifically the glue layer function.

Evaluation Example 4: Evaluation concerning Production Example 3

1) First, the voltage stability of the pellet sintered body of Production Example 3 was evaluated, and 2) the voltage stability of the solid electrolytic cell of Production Example 3 was evaluated. A battery containing a small amount of liquid electrolyte was produced with the pellet sintered body, and the charge and discharge characteristics thereof were evaluated. 3) A pre-solid battery including only the pellet sintered body of Production Example 3 and containing no liquid electrolyte was prepared , And evaluated.

(1) Evaluation of voltage stability of the pellet sintered body of Production Example 3

First, the stability window of the pellet sintered body of Production Example 3 was measured to examine the reactivity in all regions, high voltage and low voltage.

Specifically, metal lithium (Li) was deposited on one side of the pellet sintered body (sintering temperature: 950 占 폚) of Production Example 3 having a thickness of 250 占 퐉 to a thickness of 3 占 퐉 or more using a vacuum thermal deposition method, On the surface, gold (Au) was deposited to a thickness of 300 nm by a sputtering method.

The surface on which the gold (Au) was deposited was used as a working electrode and the surface on which the lithium (Li) was deposited was used as a counter and a reference electrode.

Starting from an open circuit voltage (OCV) at a scan rate of 0.1 mV / sec, the battery was subjected to a cyclic voltage (cyclic voltage) cycle in the potential range of 5.3 to 0 V (vs. Li / Li ⁺ voltammogram) were measured.

Fig. 23 shows the potential window obtained as a result of the cyclic voltammetry measurement. From 1 to 5.3 V, it can be confirmed that it is driven very stably without the decomposition reaction of the electrolyte.

At this time, the current change abruptly appearing at a low potential means a reaction due to electrodeposition and electrodissolution of lithium, and it is estimated that the pellet sintered body of Production Example 3 does not react with lithium.

Therefore, the pellet sintered body of Production Example 3 can be evaluated that the voltage stability in all regions is ensured.

(2) Evaluation of charge / discharge characteristics of the battery including the pellet sintered body of Production Example 3

In fact, prior to the production of the entire solid battery, a battery containing a small amount of liquid electrolyte together with the pellet sintered product of Production Example 3 was prepared and evaluated for its charge-discharge characteristics.

Specifically, for a pellet sintered body (sintering temperature: 950 캜) of Production Example 3 having a thickness of 250 탆, metallic lithium (Li) was deposited on one side by vacuum thermal evaporation to a thickness of 3 탆, , An electrode was placed, and the inside of the electrode was impregnated with a liquid electrolyte to prepare a battery.

At this time, the electrode, LiNi _{0. 8} Co _{0 . 1} Mn _{0 . 1} O using the positive electrode active material (NCM811) of the _second composition and the mixture containing the positive electrode active material, binder, and conductive material 92: the weight ratio of 4:04 to the (base sequence, the positive electrode active material: conductive material: binder) , The mixture was uniformly applied on an aluminum (Al) foil having a thickness of 15 μm and dried as conventionally known to obtain an electrode having a 50 μm-thick active material layer.

The liquid electrolyte was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7 (EC: EMC) in a volume ratio of 1.2 M Of LiPF ₆ were dissociated.

The electrode was impregnated with the liquid electrolyte by wetting sufficiently, but the periphery of the electrode was well sealed with the pellet sintered product of Production Example 3 so as not to come into contact with metal lithium (Li).

FIG. 24 shows a graph of a tenth charge / discharge cycle of the battery, and a graph corresponding to a voltage profile of a typical nickel-manganese-cobalt (NMC) system is confirmed. Specifically, the discharge capacity at the 10th cycle (114.2 mA) at a charge / discharge condition of 0.1 C rate is 114.4 mAh / g, which means that 58% of the reference capacity is maintained.

From these results, it is estimated that the pellet-sintered product of Production Example 3 performs well the function of conducting lithium (Li) ions when applied to a battery containing a small amount of liquid electrolyte.

(3) Characteristic evaluation of all solid-state batteries including the pellet-sintered body of Production Example 3

Further, a full solid battery including only the pellet sintered product of Production Example 3, without containing any liquid electrolyte, was prepared, and its characteristics were evaluated.

For this purpose, a 10 μm thick anode was formed on one side of the pellet sintered body (sintering temperature: 950 ° C.) of Production Example 3 having a thickness of 200 μm by a printing method, And a metal lithium was deposited on the other surface (the surface on which the anode was not formed) of the pellet sintered body by a vacuum thermal evaporation method to a thickness of 3 탆. In this manner, A solid cell was fabricated.

Specifically, the positive electrode is formed by uniformly coating the positive electrode material and then performing a heat treatment at 600 ° C. At this time, as the positive electrode material, a mixture of a positive electrode active material and an ion conductor was mixed with a binder in a weight ratio of 99.9: 0.1 (the order of description is a binder of a positive electrode active material and an ion conductor: binder).

More specifically, LiCoO ₂ was used as a cathode active material and Li ₃ BO ₃ was used as an ion conductor, and the mixture was mixed at a weight ratio of 95: 5 (the order of description is a cathode active material: Ion conductor) were used.

As the binder, cellulose (ethyl cellurose) was dissolved in ethyl alcohol (concentration: 1M).

On the other hand, gold (Au) having a thickness of 300 nm was deposited on the anode using a sputtering method. The deposited Au functions not only as a positive current collector, It was possible to perform the function of preventing impregnation of the anode.

FIG. 25 shows the life cycle of the pre-solid electrolyte cell 10 times. It is confirmed that the capacity is kept almost constant and the discharge capacity is maintained despite the 10 charge / discharge cycles.

26 is a graph showing charge / discharge characteristics of the pre-solid battery when a constant current of 10 인가 was applied to an anode area of 0.283 cm 2. According to this, it is confirmed that a discharge flattening section (plateau) appears in the 3.8 V region when driven in a voltage range of 4.2 to 3.0 V, and a capacitance of 0.1 mAh / cm 2 appears in the first discharge.

From these results, it is estimated that the pellet sintered product of Production Example 3 exhibits good lifetime characteristics and charge / discharge characteristics even when fabricated from a pre-solid battery which does not contain any liquid electrolyte.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (22)

Is a solid electrolyte containing an oxide of Garnet structure doped with boron (B) and tantalum (Ta)
Wherein the molar ratio of the boron (B) to the solid electrolyte is 0.1 or more,
Solid electrolyte.
The method according to claim 1,
The molar ratio of the tantalum (Ta) to the boron (B)
0.35 / 0.1 to 0.35 / 0.4,
Solid electrolyte.
The method according to claim 1,
Wherein the oxide of the garnet structure is further doped with aluminum (Al)
Solid electrolyte.
The method of claim 3,
The molar ratio of the aluminum (Al) to the boron (B)
0.5 / 0.1 to 0.1 / 0.4,
Solid electrolyte.
The method according to claim 1,
Wherein the solid electrolyte is represented by the following general formula (1)
Solid electrolyte.
[Chemical Formula 1]
Li _(7-ax) M ¹ _x La ₃ Zr _{2- y W} Ta _y B _z M ² _w O ₁₂
In Formula 1,
M ¹ is selected from the group consisting of Al, Na, K, Rb, Cs, Fr, Mg, Ca,
M ² is selected from the group consisting of Nb, Sb, Sn, Hf, Bi, W, Se, Ga, Ge,
0? A? 0.1,
0? X? 0.5,
0.005? Y? 0.5,
0.1? Z? 0.5,
0? W <0.15.
6. The method of claim 5,
In Formula 1,
M &^lt; ^{1 &gt;} is Al,
Solid electrolyte.
6. The method of claim 5,
In Formula 1,
0.1? Z? 0.4,
Solid electrolyte.
6. The method of claim 5,
In Formula 1,
0? X? 0.3,
Solid electrolyte.
The method according to claim 1,
The solid electrolyte has a crystal structure,
Wherein the substrate is a cubic structure.
Solid electrolyte.
The method according to claim 1,
The ionic conductivity of the solid electrolyte is,
0.9 x 10 &lt; ^-4 &gt; S / cm or more.
Solid electrolyte.
Preparing a mixed powder comprising a lithium raw material, a lanthanum raw material, a zirconium raw material, a tantalum raw material, and a boron raw material;
Pulverizing the mixed powder; And
Calcining the pulverized mixed powder to obtain a powdery solid electrolyte,
The obtained solid electrolyte is a solid electrolyte containing an oxide of Garnet structure doped with boron (B) and tantalum (Ta), and the molar ratio of boron (B) to the solid electrolyte is 0.1 or more And,
Preparing the mixed powder of the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material is a step of preparing a mixed powder of lithium, lanthanum, zirconium, and tantalum Wherein the raw materials are mixed and mixed in a molar ratio,
A method for producing a solid electrolyte.
12. The method of claim 11,
In the step of producing the mixed powder including the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material,
Wherein the molar ratio of tantalum to boron in the mixed powder is from 0.35 / 0.1 to 0.35 / 0.4.
A method for producing a solid electrolyte.
12. The method of claim 11,
In preparing the mixed powder comprising the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material,
The mixed powder,
The method of claim 1, further comprising the steps of: preparing an aluminum raw material, a sodium raw material, a potassium raw material, a rubidium raw material, a cesium raw material, a franc raw material, a magnesium raw material, a calcium raw material,
A method for producing a solid electrolyte.
12. The method of claim 11,
In preparing the mixed powder comprising the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material,
The mixed powder,
Lt; RTI ID = 0.0 &gt; aluminum, &lt; / RTI &gt;
A method for producing a solid electrolyte.
15. The method of claim 14,
In preparing the mixed powder comprising the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material,
Wherein the molar ratio of aluminum to boron in the mixed powder is 0.5 / 0.1 to 0.1 / 0.4.
A method for producing a solid electrolyte.
12. The method of claim 11,
The step of preparing the mixed powder including the lithium source material, the lanthanum source material, the zirconium source material, the tantalum source material, and the boron source material may include:
Charging each of the raw materials at a molar ratio corresponding to the molar amount of lithium, lanthanum, zirconium, and tantalum in the obtained solid electrolyte, and mixing the primary raw materials; Since the,
Further adding a lithium raw material to the primary mixed material and secondary mixing the mixture,
A method for producing a solid electrolyte.
17. The method of claim 16,
Further adding a lithium raw material to the primary mixed material and secondary mixing,
The amount of the lithium raw material to be added is,
Is 3 to 5 mol% based on the lithium raw material in the primary mixed material.
A method for producing a solid electrolyte.
12. The method of claim 11,
Calcining the pulverized mixed powder to obtain a powdery solid electrolyte; Since the,
Forming the obtained solid electrolyte into a pellet; And
And sintering the formed pellets. &Lt; RTI ID = 0.0 &gt;
A method for producing a solid electrolyte.
19. The method of claim 18,
The step of sintering the formed pellets comprises:
Lt; RTI ID = 0.0 &gt; 850 &lt; / RTI &gt;
A method for producing a solid electrolyte.
19. The method of claim 18,
The step of sintering the formed pellets comprises:
RTI ID = 0.0 &gt; 7-20 &lt; / RTI &gt;
A method for producing a solid electrolyte.
12. The method of claim 11,
The step of pulverizing the mixed powder comprises:
A ball mill, a mortar, a sieve, an attrition mill, a disk mill, a jet mill, a jaw crusher, a crusher crusher, or a combination thereof.
A method for producing a solid electrolyte.
anode;
cathode; And
Comprising a solid electrolyte,
Wherein the solid electrolyte is a solid electrolyte including an oxide of Garnet structure doped with boron (B) and tantalum (Ta), wherein the molar ratio of the boron (B) to the solid electrolyte is 0.1 or more,
Lithium secondary battery.

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