Electrolytes with ultra-high closoborate concentrations

Abstract

To provide a solid electrolyte for an electrochemical device with high ionic conductivity.SOLUTION: An ultra-high closo-borate concentration solid state electrolyte is provided that is a combined salt of an alkali metal or alkaline earth metal closo-borate and a conductivity-increasing SISE. The combined salts allow significantly higher conductivity in the solid state than the contained alkali metal or alkaline earth metal closo-borate. The combined salts can be prepared by mechanical combination or combination in solution. This salt can be used in a solid state electrochemical device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to electrochemical cells, and more particularly to electrolytes containing borane salts for batteries. [Background technology]

[0002] background Solid-state electrolytes offer many advantages in secondary battery design, including mechanical stability, nonvolatility, and ease of construction. Typical inorganic solid-state electrolytes with high ionic conductivity are hard materials that may fail after battery cycling due to insufficient contact with the electrode materials. Polymer and other organic solid-state electrolytes overcome poor contact with cycling due to their "soft" nature. Unfortunately, these electrolytes typically exhibit low ionic conductivity.

[0003] Batteries based on the Li-ion rocking chair mechanism have been developed in which Li + ions into the active material, and during electrochemical oxidation, Li + Extract the ions. Li + The repeated insertion and extraction of ions causes a change in the volume of the electrolyte and electrode materials. In the case of a liquid electrolyte battery, the change in volume of the active material occurs when the electrolyte is Li + This has little effect on the ability to transport ions over time. However, in solid-state batteries, the solid electrolyte is subjected to mechanical stress, which can physically degrade and cause cracks in the solid electrolyte layer. Electrolyte cracking can lead to internal short circuits or battery failure due to loss of electrical conductivity of the solid electrolyte. Summary of the Invention [Problem to be solved by the invention]

[0004] SISEs based on soft ionic solid-state electrolytes (SISEs), such as organic ionic plastic crystals (OIPCs), exhibit intermediate states between the extremes of inorganic electrolytes and polymer and organic solid-state electrolytes, respectively. The non-flammable, non-volatile, soft, and highly electrochemically and thermally stable nature of SISEs offers great promise for battery applications. These SISEs can be further doped with lithium salts for use as lithium ion conductors. The solubility of the lithium salts in these SISEs is limited, and the resulting compositions contain Li ions below their solubility limit. + The ion concentration is often insufficient to achieve the desired conductivity.

[0005] Therefore, to achieve robust and ultra-concentrated solid-state electrolytes of lithium closoborate salts in SISEs, it is still necessary to increase the lithium concentration beyond the saturation limit in the molten mixture at high temperatures, so as to obtain solid-state electrolytes that exhibit higher conductivity at room temperature compared to the parent starting materials. [Means for solving the problem]

[0006] overview In various non-limiting embodiments, LiCB in at least one soft ionic solid electrolyte SISE having closoborate anions. 11 H 12 or other alkali metal or alkaline earth metal closoborates, wherein at least one SISE has the structure [(CR 1 R 2 ) n ] w Z(R 3 ) 4-2w + (n is 4 to 6, w is 0 to 2, Z is N or P) and has an ammonium or phosphonium cation. 1 and R 2 The groups are independently hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C6-C 14 Aryl, or C6-C 14aryloxy, where the carbon is unsubstituted or substituted one or more times with fluorine, alkyl, partially fluorinated or perfluorinated alkyl, alkoxy, partially fluorinated or perfluorinated alkoxy, phenyl, partially fluorinated or perfluorinated phenyl, phenoxy, or partially fluorinated or perfluorinated phenoxy, and any alkyl or alkoxy group is linear, branched, or cyclic. 3 The groups are independently C1-C8 alkyl or C6-C1 aryl, where the carbons are unsubstituted or substituted one or more times with fluorine, alkyl, partially fluorinated or perfluorinated alkyl, alkoxy, partially fluorinated or perfluorinated alkoxy, phenyl, partially fluorinated or perfluorinated phenyl, phenoxy, or partially fluorinated or perfluorinated phenoxy, and any alkyl or alkoxy group is linear, branched, or cyclic. When w is 0 or 1, R 3 The group may contain at least two different structures, or all R 3 When the groups are identical, R 3 Although the group contains a chiral center, the combined R 3 is racemic. When w is 2, two spiro-ammonium or phosphonium ions [(CR 1 R 2 ) n ]Z + The ring structures can be different, or two [(CR 1 R 2 ) n ]Z + If the rings are identical, CR 1 R 2 At least one of the R 1 and R 2 group, and R 1 and R 2 The groups are randomly positioned on both sides of the structure, for example, randomly positioned on the axial and equatorial positions of a ring where n=5. The Z atom may be, but is not necessarily, a chiral center, or R 1 , R 2 Or R3 Any of the groups may, but need not, be a chiral center. + The concentration exceeds the solubility of the lithium closoborate salt in the SISE when processed without prolonged heating of the mixture at elevated temperatures, resulting in a room temperature conductivity that is higher than that of the neat lithium closoborate salt.

[0007] One embodiment provided herein is an ammonium or phosphonium CB 11 H 12 LiCB combined at ultra-high concentrations in a mixture with at least one SISE that is a salt 11 H 12 This method is a method for preparing a lithium closoborate salt or other alkali or alkaline earth metal closoborate salt. Ultra-high concentrations are concentrations that exceed the saturation concentration of the Li salt in a liquid-phase mixture with the SISE. The lithium closoborate salt is combined with the SISE and heated to at least 160°C to form a mixture, which is held at that temperature for a period of time sufficient to form a partially fluid phase or composition. The mixture may be stirred to improve mixing between its components. By not reaching a high temperature or maintaining that temperature for a sufficient period of time, the mixture may become viscous, e.g., LiCB 11 H 12 If the mol percent is greater than about 45 mole percent, it will contain some portion of the starting salt upon cooling.

[0008] In one embodiment provided herein, an ultra-high concentration alkali metal or alkaline earth metal closoborate / SISE mixture is a solid electrolyte for a solid-state electrochemical device. Accordingly, provided herein is an electrochemical device comprising an anode, a cathode, and an ultra-high concentration alkali metal or alkaline earth metal closoborate / SISE mixture that is a solid electrolyte in contact with the anode and cathode. The electrochemical device may be a secondary battery or a subunit of a secondary battery. The anode is the electrode that undergoes oxidation during device discharge and reduction during device charging. Similarly, the cathode is the electrode where reduction of the cathode material occurs during device discharge and oxidation of the cathode material occurs during device charging.

[0009] These and other features of the electrolyte and its preparation will become apparent from the following detailed description when read in conjunction with the drawings and examples which are illustrative and not limiting.

[0010] For a better understanding of the processes and devices involving ultra-high concentration lithium-containing electrolytes, in conjunction with the specific variations and examples described herein, reference is made to the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] Figure 1 shows a composite Arrhenius plot of the conductivity of LiCB11H12 at 100, 81, 80, 62 (ultra-high concentration), 45, 37, 20, and 0 mole percent in organic ionic plastic crystals (SISEs) such as Pyr14CB11H12, showing that the ionic conductivity of the combined salts is higher than that of neat LiCB11H12(·) at temperatures below approximately 70 °C. [Figure 2] FIG. 2 shows a bar graph of activation energy for Li+ conductivity of homogeneous mixtures, where the low temperature phase reflects the slope at low temperatures in the plot of FIG. 1, and the high temperature phase reflects the slope at high temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0012] The drawings described herein are intended to illustrate general features of methods and devices, among other features of the present technology. It should be noted that the drawings may not precisely reflect the features of a given aspect and are not necessarily intended to define or limit specific embodiments within the scope of the present teachings.

[0013] Detailed Description The present disclosure provides ultra-high concentration lithium solid-state electrolytes, other alkali metal electrolytes, or alkaline earth metal electrolytes, and 11 H 12 , or other alkali metal, or alkaline earth metal closoborate is included with at least one organic ionic plastic crystal (SISE) or SISE-like material. Lithium closoborate is included at a concentration greater than the saturation concentration of the solution formed upon mixing of the components in the molten state. As used herein, a SISE may be a SISE-like component that has long-range order, excluding short-range disorder that may result from rotational motion of molecules occurring at one or more solid-solid phase transitions that allow the onset of molecular rotation. Any reference herein to a SISE may also refer to compositions that may be conventionally characterized as solid electrolytes (SEs) and / or SISE-like materials, and SISEs include compositions disclosed herein without implying that the SISEs herein have the specific properties of conventional SISEs. CB 11 H 12 -1 In addition to the closoborate anion, B 12 H 12 -2 or any substituted derivative thereof.

[0014] The closoborate anion has the structure [B y H (y-z-i) R z X i ] -2 , [CB (y-1) H (y-z-i) R z X i ]- , [C2B (y-2) H (y-t-j-1) R t X j ] - , [C2B (y-3) H (y-t-j) R t X j ] - or [C2B (y-3) H (y-t-j-1) R t X j ] -2 , where y is 6 to 12, z is 0 to y, i is 0 to yz, t is 0 to (y-1), j is 0 to (y-1-t), X is independently a halogen, R is independently alkyl, alkoxy, aryl, alkylaryl, arylalkyl, or aryloxy, where alkyl can be linear, branched, or cyclic, and any R is unsubstituted, partially fluorinated, or fully fluorinated. The halogen can be F, Cl, Br, or I.

[0015] SISE is a structure [(CR 1 R 2 ) n ] w Z(R 3 ) 4-2w + where n is 4 to 6, w is 0 to 2, and Z is N or P. 1 and R 2 The groups are independently hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C6-C 14 Aryl, or C6-C 14aryloxy, where the carbon is unsubstituted or substituted one or more times with fluorine, alkyl, partially fluorinated or perfluorinated alkyl, alkoxy, partially fluorinated or perfluorinated alkoxy, phenyl, partially fluorinated or perfluorinated phenyl, phenoxy, or partially fluorinated or perfluorinated phenoxy, and any alkyl or alkoxy group is linear, branched, or cyclic. 3 The groups are independently C1-C8 alkyl or C6-C 14 aryl, wherein the carbon is unsubstituted or substituted one or more times with fluorine, alkyl, partially fluorinated or perfluorinated alkyl, alkoxy, partially fluorinated or perfluorinated alkoxy, phenyl, partially fluorinated or perfluorinated phenyl, phenoxy, or partially fluorinated or perfluorinated phenoxy, and any alkyl or alkoxy group is linear, branched, or cyclic. When w is 0 or 1, R 3 The group may contain at least two different structures, or all R 3 When the groups are identical, R 3 Although the group contains a chiral center, the combined R 3 is racemic. When w is 2, two spiro-ammonium or phosphonium ions [(CR 1 R 2 ) n ]Z + The ring structures can be different, or two [(CR 1 R 2 ) n ]Z + If the rings are identical, CR 1 R 2 At least one of the R 1 and R 2 group, and R 1 and R 2 The groups are randomly positioned on both sides of the structure, for example, randomly positioned on the axial and equatorial positions of a ring where n=5. The Z atom may be, but is not necessarily, a chiral center, or R 1 , R 2Or R 3 Any of the groups may, but need not, be a chiral center. Partially fluorinated alkyl, alkoxy, phenyl, or phenoxy groups are those in which not all hydrogens are replaced with fluorine. Ultra-high concentration lithium electrolytes are mixtures processed in at least a partial molten state at high temperatures that exhibit higher conductivity than neat lithium closoborate or saturated solutions formed by mixing in the high-temperature molten state. Ultra-high concentration electrolytes are easily pressed under relatively low uniaxial pressure to form pellet-like layered structures. The electrolyte composition can have an equal or greater mole fraction of lithium closoborate in the SISE. For example, the mole ratio of lithium closoborate to SISE material can be 1:1, 2:1, 3:1, 4:1, or higher.

[0016] In other embodiments, lithium closoborate can be substituted for sodium closoborate, magnesium closoborate, or any other alkali or alkaline earth metal closoborate used as an electrolyte for sodium batteries, magnesium batteries, or any alkali or alkaline earth metal batteries. SISEs or SISE-like materials may be similar to those used with lithium closoborate. In other embodiments of the present invention, the closoborate anion of the SISE may be substituted or combined with a triflate anion, a bis(trifluoromethanesulfonyl)imide anion, a bis(fluorosulfonyl)imide anion, a tetrafluoroborate anion, a hexafluorophosphate anion, or any combination thereof. It should be understood that, in the following specification, lithium closoborate can be substituted with any alkali or alkaline earth metal closoborate, and the SISE does not exclude anions other than closoborate.

[0017] In one embodiment, the ultra-high concentration lithium electrolyte is formed as a layer. In this method, lithium closoborate and at least one SISE are combined as solids and then crushed or milled to form a mixed powder. The mixed powder is heated to a temperature of at least 160°C to achieve a fluid state, such as a molten or partially molten state. The fluid state is stirred or otherwise agitated for a sufficient period, e.g., more than one hour, and then cooled to room temperature to obtain a mixture malleable enough to be pressed into a layer under relatively low pressure. The preheated mixture can be mechanically milled or otherwise pulverized to break the combined lithium closoborate SISE-like mixed salt into particles having micrometer or nanometer dimensions. Ball milling, jet milling, and other milling or grinding techniques can be applied to achieve sufficient dispersion of the two or more salts. After blending the particles, heat can be applied to make the mixture fluid, and stirring can be used to promote diffusion into a SISE or SISE-like, continuous lithium closoborate / SISE composition. These compositions can be converted into solid electrolyte layers for inclusion in batteries or other electrochemical devices using a press or roller under relatively low pressure to provide a form that can be inserted into the electrochemical device.

[0018] In one embodiment, the ultra-high concentration lithium electrolyte is included in an electrochemical device, such as a secondary battery or a subunit of a secondary battery. The anode is the electrode where oxidation occurs during device discharge and reduction occurs during device charging. Similarly, the cathode is the electrode where reduction of the cathode material occurs during device discharge and oxidation of the cathode material occurs during device charging.

[0019] The anode can include any material or combination of materials effective to participate in the electrochemical oxidation of a metal during discharge of the device. Similarly, the anode can include any material or combination of materials effective to participate in the electrochemical reduction of lithium cations and incorporate reduced lithium during charging of the device. In embodiments, the anode can consist essentially of elemental lithium or include at least one surface layer of elemental lithium.

[0020] The cathode may include any material or combination of materials that allows electrochemical insertion of a cathode material during device discharge. Similarly, the cathode may include any material or combination of materials for electrochemical extraction of a cathode material during device charging. In some variations, the cathode material inserted into the cathode during device discharge and extracted from the cathode during device charging events may include lithium. The cathode may also include any material capable of storing cations through a conversion mechanism.

[0021] SISE or SISE-like materials with LiCB 11 H 12 The ultra-high concentration lithium electrolyte formed by combining it with lithium closoborate, such as HCl, can exhibit conductivity at room temperature that is more than twice that of neat lithium closoborate or of a saturated solution of lithium closoborate in a SISE. As can be seen in Figure 1, at room temperature, + The conductivity of N-butyl-N-methylpyrrolidinium 1-carba-closo dodecaborate (Py 14 CB 11 H 12 ) in Neat LiCB 11 H 12 and about 45 mol% LiCB 11 H 12 The saturated solution of Py formed by treatment at temperatures above 160°C for more than 1 hour is almost equivalent. 14 CB 11 H 12 LiCB inside 11 H 12The composition having 80 mol % of LiCB at room temperature 11 H 12 It exhibits approximately two times higher conductivity than neat LiCB at temperatures below approximately 60°C. 11 H 12 It exhibits higher conductivity than

[0022] The ability to create mixtures beyond the solubility limit of lithium closoborate salt in a solute and achieve conductivities significantly higher than the weighted average of neat lithium closoborate and saturated solutions was unexpected. This appears to indicate the formation of a new phase, rather than the dispersion of individual islands of lithium closoborate salt in contact with a saturated solution of lithium closoborate dissolved in a SISE. SISEs or SISE-like materials form a distinct phase, which is effectively the SISE "dissolved" in lithium closoborate. The formation of a distinct phase is evident from the activation energy of Li mobility, which is different from that of Li salts or other compositions below the saturated solubility limit. The phases that form exhibit lower Li concentrations than compositions prepared within the limits of saturation concentration. + Provide a material with an activation energy for migration, LiCB, as shown in Figure 2. 11 H 12 / Py 14 CB 11 H 12 For the material formed upon heating the mixture, all concentrations below 100 mole percent exhibit higher ionic mobility.

[0023] Various aspects of the present disclosure are further described with reference to the following examples, which are provided to illustrate particular embodiments of the present disclosure and should not be construed as limiting the scope of the present disclosure to any particular aspect.

[0024] Example 1: LiCB 11 H 12 / Py 14 CB 11 H 12 Preparation of In a mortar, LiCB at a molar ratio of 80:20 11 H 12 Py14 CB 11 H 12 The combined salts were ground with a pestle until a homogeneous particle mixture was formed. The mixture was transferred to a container and heated at 160°C for 24 hours. The partially molten mixture was stirred to form a mixture. After cooling, the LiCB 11 H 12 / Py 14 CB 11 H 12 The mixture was cooled to room temperature. The mixture was placed in a press and compressed under 3 tons into pellets. Its conductivity was measured at various temperatures, as shown in Figure 1.

[0025] The above description is merely exemplary in nature and is not intended to limit the present disclosure or the application or uses of the present disclosure. As used herein, the phrase "at least one of A, B, and C" should be interpreted as meaning "A or B or C" using the non-exclusive logic "or." It is understood that the principles of the present disclosure are not altered even if the various steps included in a method are performed in a different order. The disclosure of ranges includes the disclosure of all individual ranges and individual subranges included in the entire range.

[0026] The headings (e.g., "Background" and "Summary") and subheadings used herein are intended only to generally organize topics within the scope of the present disclosure and are not intended to limit the disclosure of the technology or any aspect thereof. The description of multiple embodiments having described features is not intended to exclude other embodiments having additional features or other embodiments incorporating different combinations of the described features.

[0027] As used herein, the terms "comprises" and "includes," and variations thereof, are intended to be non-limiting, and a sequential description or listing of items does not exclude other similar items that may be useful in the devices and methods of the present technology. Similarly, the terms "can" and "may" and variations thereof are intended to be non-limiting, and a description that an embodiment can or may include a particular element or feature does not exclude other embodiments of the present technology that do not include such element or feature.

[0028] The broad teachings of the present disclosure can be embodied in a variety of forms. Thus, while the present disclosure includes specific examples, other modifications will become apparent to those skilled in the art upon studying the specification and the following claims, and the true scope of the present disclosure should not be limited to the specific examples contained therein. Reference herein to an aspect or various aspects means that a specific feature, structure, or characteristic described in connection with an embodiment or a particular system is included in at least one embodiment or aspect. When the phrase "in one aspect" (or variations thereof) appears, it does not necessarily refer to the same aspect or embodiment. It should also be understood that the various method steps described herein do not necessarily have to be performed in the same order as described, and that not every method step is required for every aspect or embodiment.

[0029] The above-described description of the embodiments is provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a specific embodiment are generally not limited to that specific embodiment and, where appropriate, may be interchangeable and used in selected embodiments without specific labeling or description. Furthermore, individual elements or features of a specific embodiment may be modified in various ways. Such modifications should not be considered a departure from the scope of the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

Claims

1. 1. A method for preparing an ultra-high closoborate concentration solid electrolyte, the method comprising: combining at least one alkali metal or alkaline earth metal closoborate salt with at least one soft ionic solid-state electrolyte (SISE); In the at least one alkali metal or alkaline earth metal closoborate salt, the alkali metal or alkaline earth metal cation selected from lithium, sodium, potassium, and magnesium is structure [B ｙ H （ｙ－ｚ－ｉ） R ｚ X ｉ ] －２ , [CB （ｙ－１） H （ｙ－ｚ－ｉ） R ｚ X ｉ ] － , [C ２ B （ｙ－２） H （ｙ－ｔ－ｊ－１） R ｔ X ｊ ] － , [C ２ B （ｙ－３） H （ｙ－ｔ－ｊ） R ｔ X ｊ ] － or [C ２ B （ｙ－３） H （ｙ－ｔ－ｊ－１） R ｔ X ｊ ] －２ and paired with at least one closoborate anion having the formula: During the ceremony, y is 6 to 12; z is 0 to y; i ranges from 0 to yz; t is 0 to (y-1); j is 0 to (y-1-t), X is independently a halogen; R is independently alkyl, alkoxy, aryl, alkylaryl, arylalkyl, or aryloxy, wherein said alkyl may be linear, branched, or cyclic, and any R is unsubstituted, partially fluorinated, or fully fluorinated; The at least one soft ionic solid-state electrolyte (SISE) comprises at least one organic cation combined with the closoborate anion and / or at least one of triflate anion, tetrafluoroborate anion, bis(trifluoromethanesulfonyl)imide anion, bis(fluorosulfonyl)imide anion, hexafluorophosphate anion, or any combination thereof, wherein the at least one organic cation is structure [(CR １ R ２ ) ｎ ] ｗ Z(R ３ ) ４－２ｗ ＋ and wherein the ammonium or phosphonium ion has the formula: During the ceremony, n is 4 to 6; w is 0 to 2; Z is N or P; R １ and R ２ are independently hydrogen, C １ -C ８ Alkyl, C １ -C ８ Alkoxy, C ６ -C １４ aryl, or C ６ -C １４ aryloxy, wherein the carbon is unsubstituted or substituted one or more times with fluorine, alkyl, monofluorinated to perfluorinated alkyl, alkoxy, monofluorinated to perfluorinated alkoxy, phenyl, monofluorinated to perfluorinated phenyl, phenoxy, or monofluorinated to perfluorinated phenoxy, and any alkyl or alkoxy group is linear, branched, or cyclic; R ３ are independently C 1 -C 8 alkyl or C 6 -C 14 aryl, wherein the carbons are unsubstituted or substituted one or more times with fluorine, alkyl, partially fluorinated alkyl, perfluorinated alkyl, alkoxy, partially fluorinated alkoxy, perfluorinated alkoxy, phenyl, partially fluorinated phenyl, perfluorinated phenyl, phenoxy, partially fluorinated phenoxy, perfluorinated phenoxy, and any alkyl or alkoxy group is linear, branched, or cyclic; The conductivity of the combined salts at room temperature is greater than the conductivity of the alkali metal or alkaline earth metal closoborate salt at room temperature and the conductivity of the mixed salts at a molar ratio of a saturated solution of the alkali metal or alkaline earth metal closoborate salt in the SISE, and the method further comprises: grinding or milling the combined alkali or alkaline earth metal closoborate salt and the SISE to form a ground alkali or alkaline earth metal closoborate / SISE salt; and heating the ground alkali metal or alkaline earth metal closoborate / SISE salt at a temperature of at least 160° C. for at least 1 hour to form an alkali metal or alkaline earth metal closoborate / SISE salt.

2. 2. The method for preparing an ultra-high closoborate concentration solid electrolyte according to claim 1, wherein the grinding is carried out with a mortar and pestle.

3. 2. The method for preparing an ultra-high closoborate concentration solid electrolyte according to claim 1, wherein the milling is ball milling or jet milling.

4. 2. The method for preparing an ultra-high closoborate concentration solid-state electrolyte according to claim 1, wherein the ground alkali or alkaline earth metal closoborate / SISE salt comprises particles of nanometer or micrometer dimensions.

5. 2. The method for preparing an ultra-high closoborate concentration solid-state electrolyte according to claim 1, wherein the step of heating the pulverized alkali metal or alkaline earth metal closoborate / SISE salt involves stirring or agitation.

6. The at least one SISE is Py １４ CB １１ H １２ 2. The method for preparing the ultra-high closoborate concentration solid electrolyte according to claim 1, wherein

7. The at least one alkali metal or alkaline earth metal closoborate salt is LiCB １１ H １２ 2. The method for preparing the ultra-high closoborate concentration solid electrolyte according to claim 1, wherein

8. 2. The method for preparing an ultra-high closoborate concentration solid-state electrolyte according to claim 1, wherein the molar ratio of the at least one alkali metal or alkaline earth metal closoborate salt to the at least one SISE is at least 1:

1.

9. 2. The method for preparing an ultra-high closoborate concentration solid-state electrolyte according to claim 1, wherein the molar ratio of the at least one alkali metal or alkaline earth metal closoborate salt to the at least one SISE is at least 4:

1.

10. Cooling to room temperature; 2. The method for preparing an ultra-high closoborate concentration solid-state electrolyte according to claim 1, further comprising the step of pressing or rolling the lithium closoborate / SISE salt, wherein the ultra-high closoborate concentration solid-state electrolyte is in the form of a sheet.

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