Solid Electrolyte for Improving Battery Performance

Abstract

Provided are solid electrolytes for use in lithium-ion (Li-ion) batteries, methods for synthesizing the solid electrolytes, methods for making the solid electrolytes into membranes, and methods for using the solid electrolytes in Li-ion batteries. Solid electrolyte pellets can be made in solution, and membranes can be formed using the synthesized pellets for use in Li-ion batteries.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of U.S. Provisional Application No. 63 / 140,570, filed on January 22, 2021, and is incorporated by reference in its entirety, including all drawings.

Background Art

[0002] The research on lithium - ion conductive solid electrolytes has been mainly driven by the need to develop a safer alternative to the flammable liquid electrolytes in lithium - ion batteries. The research on solid electrolytes has shown various advantages of these materials, including improved energy density, rate capability, and cyclability of the battery. Solid electrolytes belong to two main categories: organic and inorganic. Organic solid electrolytes mainly include lithium - ion conductive polymers, and inorganic solid electrolytes mainly include lithium - ion conductive ceramics and glasses.

[0003] The use of solid polymer electrolytes in lithium - based batteries began in the 1980s after the discovery of lithium - ion conductivity in polyethylene oxide (PEO) - based systems (Non - Patent Document 1). Since then, various lithium - ion conductive polymers (e.g., poly(acrylonitrile), poly(methyl methacrylate), and poly(vinylidene fluoride)) have been studied for use in all - solid - state polymer lithium - ion batteries.

[0004] The research on the use of inorganic solid electrolytes began with the development of lithium phospho - oxynitride (LiPON) at Oak Ridge National Laboratory in the 1990s (Non - Patent Document 2, Non - Patent Document 3). Since then, other inorganic lithium - ion conductive materials such as perovskite, sodium superionic conductor (NASICON), garnet, and sulfide - type materials have been used (Non - Patent Document 4, Non - Patent Document 5). Since the 2000s, solid electrolytes have been used in newly emerging lithium - ion batteries such as lithium - air batteries, lithium - sulfur batteries, and lithium - bromine batteries.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Summary of the Invention

Means for Solving the Problems

[0006] Embodiments of the present invention provide novel and advantageous solid electrolytes (e.g., lithium palladium sulfide) for use in lithium ion (Li ion) batteries, methods of synthesizing the solid electrolytes, methods of fabricating the solid electrolytes into films, and methods of using the solid electrolytes in Li ion batteries. The solid electrolytes of the embodiments provide improved stability of the battery over cycle life (e.g., exceeding 650 cycles), also the ability of the battery to resist lithium anode corrosion, and / or protection of the battery from short circuits by blocking dendrite formation and electrolyte penetration (crossover). Solid electrolyte pellets can be made in solution, used to form films, and used in Li ion batteries. Batteries containing the solid electrolyte exhibit higher stability and lower capacity fade over the life of many cycles (e.g., 650 cycles).

[0007] In one embodiment, the battery includes an anode, a cathode, and a solid electrolyte disposed between the anode and the cathode, at least one of the anode and the cathode contains lithium, and the solid electrolyte contains lithium palladium sulfide (LPS), lithium platinum sulfide, lithium rhodium sulfide, lithium iridium sulfide, lithium osmium sulfide, lithium ruthenium sulfide, lithium silver sulfide, or lithium cobalt sulfide. Both the anode and the cathode can contain lithium. The cathode can contain, for example, lithium iron phosphate (LFP), nickel cobalt aluminum (NCA), or nickel manganese cobalt (NMC). The anode can be, for example, a lithium metal anode. The solid electrolyte can have an ionic conductivity of, for example, 0.10 millisiemens / cm (mS / cm) or more. The battery can further include a separator (e.g., a polypropylene separator) disposed between the anode and the cathode. The solid electrolyte can include a first film coated on the anode, the solid electrolyte can include a second film coated on the cathode, and / or the solid electrolyte can include a third film coated on the separator. The battery can be a Li-ion battery, a lithium-air (Li-air) battery, or a lithium-sulfur (Li-sulfur) battery. The solid electrolyte can be disposed, for example, in the form of a film having a thickness of at least 20 nanometers (nm), at least 20 micrometers (μm), at least 100 μm, at most 100 μm, about 20 μm, or about 100 μm. The battery can have a capacity higher than 50% of the theoretical capacity after at least 450 1C cycles. The battery can have a capacity higher than 80% of the theoretical capacity after at least 200 1C cycles. The battery can have a capacity higher than 80% of the theoretical capacity after at least 300 1C cycles.

[0008] In other embodiments, a method of manufacturing a solid electrolyte can include a step of producing a powder and a step of producing a solid electrolyte film from the powder. The solid electrolyte can include LPS, lithium platinum sulfide, lithium rhodium sulfide, lithium iridium sulfide, lithium osmium sulfide, lithium ruthenium sulfide, lithium silver sulfide, or lithium cobalt sulfide. The step of producing the powder can include dissolving a first salt, a lithium salt, and a sulfur source in a first solvent to form a first solution, heating the first solution at a first temperature for a first time to precipitate a sulfide compound containing a first component from the lithium and the first salt, and drying the sulfide compound at a second temperature for a second time to obtain a powder. The first salt can be a palladium salt, a platinum salt, a rhodium salt, an iridium salt, an osmium salt, a ruthenium salt, a silver salt, or a cobalt salt, and the first component can be palladium, platinum, rhodium, iridium, osmium, ruthenium, silver, or cobalt. Alternatively, the step of producing the powder can include dissolving a second salt, a lithium salt, and a sulfur source in a second solvent to form a second solution, impregnating a disk with the second solution, placing the impregnated disk between a positive electrode and a negative electrode to form a first cell, heating the first cell at a third temperature for a third time while performing a constant potential operation in the first cell to precipitate a sulfide compound containing a second component from the lithium and the second salt onto the negative electrode, and recovering the sulfide compound from the negative electrode to obtain a powder. The second salt can be a palladium salt, a platinum salt, a rhodium salt, an iridium salt, an osmium salt, a ruthenium salt, a silver salt, or a cobalt salt, and the second component can be palladium, platinum, rhodium, iridium, osmium, ruthenium, silver, or cobalt. Alternatively, the step of producing the powder can include using a ball mill to mix lithium sulfide (Li2S) and a second sulfide containing a transition metal to form a ball mill mixed compound, milling the ball mill mixed compound at a first rate for a fourth time to form a sulfide compound containing lithium and the transition metal, and drying the sulfide compound at a fourth temperature for a fifth time to obtain a powder. The transition metal can be palladium, platinum, rhodium, iridium, osmium, ruthenium, silver, or cobalt.This method can further include, for example, any of the features described herein in the examples.

[0009] In other embodiments, a method of manufacturing a battery can include a step of manufacturing a solid electrolyte as disclosed herein, a step of depositing the solid electrolyte by coating the solid electrolyte on an anode of the battery, a step of coating it on a cathode of the battery, and / or a step of coating it on a separator of the battery.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] Embodiments of the present invention provide novel and advantageous solid electrolytes (e.g., lithium palladium sulfide) for use in lithium-ion (Li-ion) batteries, methods of synthesizing the solid electrolytes, methods of fabricating the solid electrolytes into films, and methods of using the solid electrolytes in Li-ion batteries. The solid electrolytes of the embodiments provide improved stability of the battery over cycle life (e.g., exceeding 650 cycles), also the ability of the battery to resist lithium anode corrosion, and / or protection of the battery from short circuit by blocking the formation of dendrites and crossover. Solid electrolyte pellets can be fabricated in solution, form a film using the synthesized pellets, and be used in Li-ion batteries. Batteries containing the solid electrolyte exhibit higher stability and lower capacity fade over the life of many cycles (e.g., 650 cycles).

[0012] In one embodiment, powders of the solid electrolyte material can first be fabricated. Lithium salts, platinum group metal salts or other conductive metal salts, and sulfur components (e.g., thiourea) can be dissolved in a solvent such as a polar solvent (e.g., acetone, acetonitrile, dimethyl sulfoxide, or, preferably, water). The mixture can be stirred until the components are completely dissolved and then heated (e.g., in a hydrothermal reactor) and placed in an oven at a predetermined temperature (e.g., 140° C.) for a predetermined time (e.g., 12 hours). The precipitate can then be recovered (e.g., by centrifugation) and washed at least once (e.g., 4 times) (e.g., with the same solvent used previously). Washing can be performed, for example, by resuspending in the solvent using vortexing and / or sonication, followed by centrifugation and discarding of the supernatant. The recovered solid can then be dried (e.g., at a set temperature (e.g., 60° C.), optionally under vacuum, until completely dry). The dried solid can then be pulverized into fine powder (e.g., using ball milling, optionally under an inert atmosphere such as an argon atmosphere). The resulting powder can be stored (e.g., in an inert atmosphere such as under argon) until used in fabricating solid electrolyte pellets and / or composite gel polymer electrolyte membranes.

[0013] The lithium salt can be, for example, lithium nitrate, lithium carbonate, lithium acetate, lithium sulfate, or lithium phosphate, but the embodiments are not limited thereto. The platinum group metal salt or other conductive metal salt can be, for example, a palladium salt, a platinum salt, a rhodium salt, an iridium salt, an osmium salt, a ruthenium salt, a silver salt, or a cobalt salt, but the embodiments are not limited thereto. The platinum group metal salt or other conductive metal salt can be a nitrate (e.g., palladium nitrate, platinum nitrate, rhodium nitrate, iridium nitrate, osmium nitrate, ruthenium nitrate, silver nitrate, cobalt nitrate), a carbonate, an acetate, a sulfate, or a phosphate, but the embodiments are not limited thereto.

[0014] In some embodiments, the lithium salt can be replaced and a sodium salt or a magnesium salt can be used instead (e.g., sodium nitrate or magnesium nitrate). Ternary compounds such as sodium palladium sulfide and / or magnesium palladium sulfide can be produced for use in sodium ion batteries and / or magnesium ion batteries.

[0015] The prepared powder can be used to make pellets, make composite gel polymer electrolytes, and / or deposit a film of the powder material. In pellet making, the powder can be placed in a press die and compressed at a predetermined temperature (e.g., ambient temperature) for a predetermined time (e.g., 2 minutes) at a predetermined pressure (e.g., 75 MPa). The obtained pellets can be recovered and heat-treated (e.g., at 350 °C for 2 hours) to obtain the final pellets. The pellets can optionally be ground (e.g., by ball milling), repelletized, and subjected to a second heat treatment.

[0016] In the preparation of the composite gel polymer electrolyte, the powder can be mixed in a container (e.g., mortar and pestle) while adding the solution. The solution can be added dropwise. For example, it can contain 80% tetraethylene glycol dimethyl ether containing 19.5% by volume of trimethylolpropane ethoxylate triacrylate (Mn~428), 0.5% of 2-hydroxy-2-methylpropiophenone, and 1 mol / L of lithium bis(trifluoromethanesulfonyl)imide. The resulting slurry can be directly coated onto a substrate (e.g., glass substrate), or onto a separator (e.g., a polypropylene separator such as Celgard 2400), for example, using the doctor blade method. The deposited layer can be cured (e.g., using low-power ultraviolet irradiation for 20 minutes) until the film solidifies into a self-standing gel. The flexibility of the film can be controlled by the powder content. A higher powder content results in a harder film, while a lower powder content results in a more flexible film. The thickness of the film is controllable, and the thickness of the deposited layer can be in the range of, for example, 2 nanometers (nm) to 200 μm (e.g., 1 μm to 100 μm, e.g., 20 μm or about 20 μm).

[0017] In forming the film, the heat-treated pulverized powder is pelletized on a substrate (e.g., a copper substrate (e.g., 1 mm thick)) using a binder (e.g., indium foil) at a predetermined temperature and pressure for a predetermined time (e.g., 5 minutes at 175 °C and 250 kN) to obtain a sputtering target (e.g., a 2-inch or about 2-inch sputtering target). The target can then be used in a plasma coater under an inert environment (e.g., an argon environment) to deposit a film of the powder material on the substrate. The film can be deposited directly on (1) an anode as anode protection; (2) a separator as an intermediate layer, and / or (3) a cathode in a battery to prevent or suppress leakage of ions / intermediate species from the cathode (e.g., polysulfide in a Li-S battery or oxygen, nitrogen, moisture, and / or carbon dioxide in a Li-air battery). The film can be, for example, lithium palladium sulfide (LPS), lithium platinum sulfide, lithium rhodium sulfide, lithium iridium sulfide, lithium osmium sulfide, lithium ruthenium sulfide, lithium silver sulfide, or lithium cobalt sulfide. The ionic conductivity of the solid electrolyte according to embodiments of the present invention can be, for example, greater than 0.10 millisiemens per centimeter (mS / cm).

[0018] In many embodiments, the lithium-ion battery can include the solid electrolyte described herein. The film described above can be used to fabricate a lithium-ion battery having a film as an electrolyte. The cathode can be, for example, lithium iron phosphate, but the embodiments are not limited thereto. The anode can be, for example, a lithium metal anode, but the embodiments are not limited thereto. Optionally, the cathode can be impregnated with a liquid electrolyte. The lithium-ion battery can have excellent stability and performance exceeding 450 cycles (e.g., exceeding 50% of the theoretical capacity of approximately 500 cycles), and / or can operate for about 750 cycles before dropping below 50 mAh / g.

[0019] The solid electrolytes (e.g., LPS) of the embodiments of the present invention are ion conductors having ionic conductivity exceeding a threshold value for effective use in lithium-ion batteries. They are insoluble in water and organic solvents, are robust, and do not leak in the liquid phase, making them ideal for use in battery systems containing liquid electrolytes. Also, the solid electrolytes are highly stable and have thermal stability exceeding 500 °C under nitrogen.

[0020] The membranes of the embodiments of the present invention can be used as solid electrolytes in Li-ion batteries, can be used in place of separators and liquid electrolytes, or can act in cooperation with one or both of them. They can also be used as anode protection, where the anode is, for example, lithium metal, graphite, silicon, or combinations thereof, and can prevent or suppress excessive solid-electrolyte interface formation and dendrite formation. They can also be used as an intermediate layer on the separator membrane to prevent or suppress dendrite crossover or other types of crossover in other battery systems (e.g., polysulfides in lithium-sulfur batteries or oxygen, nitrogen, moisture, and / or carbon dioxide in lithium-air batteries). The membranes can also be used on the cathode side to prevent or suppress the loss of active species from the cathode (e.g., diffusion of dissolved sulfur or polysulfides from the cathode). The solid electrolyte membrane can be a pure material (e.g., LPS), a composite with a polymer electrolyte containing a binder, or a composite with a gel polymer electrolyte. The solid electrolyte membrane can be applied simultaneously to the anode, separator, and cathode, and has applications in various lithium batteries including lithium-ion, lithium-sulfur, lithium-air, lithium-silicon, and lithium-bromine batteries, as well as in sodium-ion and magnesium-ion batteries.

[0021] The synthesis method of the embodiments of the present invention is efficient and results in high-purity species that can be further purified by washing to remove Li2S, LiOH, LiNO3, PdNO3, thiourea, and / or other unreacted or by-products. This method can be used to produce many different types of solid electrolytes (e.g., LPS, lithium platinum sulfide, lithium rhodium sulfide, lithium iridium sulfide, lithium osmium sulfide, lithium ruthenium sulfide, lithium silver sulfide, and / or lithium cobalt sulfide). The solid electrolyte membrane can be made by pressure pellet, a membrane coated by a doctor blade, plasma vapor deposition, chemical vapor deposition, and / or in-situ vapor deposition in the battery from the precursors used in the synthesis. The thickness of the solid electrolyte membrane can range from 2 nm to 200 μm, and the membrane can be either non-porous or porous.

[0022] When ranges are used herein, combinations and sub-combinations of ranges (e.g., sub-ranges within the disclosed ranges) are intended to be specifically included in the particular embodiments herein. When the term "about" is used herein in conjunction with a numerical value, the value can be in the range of 95% to 105% of the value, i.e., the value can be + / 5% of the recited value. For example, "about 1 kilogram" means 0.95 kilogram to 1.05 kilogram.

[0023] The transitional phrase "comprising", "comprises" or "comprise" is inclusive or non-limiting and does not exclude additional, unrecited elements or method steps. In contrast, the transitional phrase "consisting of" excludes any element, step, or ingredient not specified in the claim. The phrases "consisting" or "consisting essentially of" indicate that the claim encompasses embodiments that include a particular material or step and embodiments that do not materially affect the basic and novel characteristics of the claim. The use of the term "comprising" contemplates other embodiments consisting of or consisting essentially of the recited components.

[0024] Embodiments of the present invention and many of their advantages can be well understood from the following examples given by way of illustration. The following examples illustrate some of the methods, uses, embodiments, and variations of the present invention. These should not, of course, be regarded as limiting the present invention. Many changes and modifications can be made with respect to the present invention.

[0025] Example 1 - Powder Preparation Lithium nitrate, palladium nitrate, and thiourea in a molar ratio of 2:3:8 were dissolved in a polar solvent (different solvents including acetone, acetonitrile, dimethyl sulfoxide, and water were used). The mixture was stirred well until completely dissolved and then added to a hydrothermal reactor and placed in an oven at 140°C for 12 hours. After the reaction was completed, the black precipitate was collected by centrifugation, resuspended in the solvent using vortexing and sonication, then centrifuged again, and the supernatant was discarded to wash four times with the same polar solvent (the one used to dissolve lithium nitrate, palladium nitrate, and thiourea). The collected solid was then dried under vacuum at 60°C until completely dry. The dried solid was then pulverized into fine powder using ball milling under an argon atmosphere. The obtained lithium palladium sulfide (LPS) powder was stored under argon until used for the preparation of solid electrolyte pellets and / or composite gel polymer electrolyte membranes.

[0026] Example 2 - Preparation of Electrolyte Pellets Using the LPS powder prepared in Example 1, 50 milligrams (mg) of the powder was placed into a half-inch pellet press die and then compressed at 75 megapascals (MPa) for 2 minutes at ambient temperature. The obtained pellet was recovered and heat-treated at 350 °C under nitrogen for 2 hours. Then, this pellet was pulverized by ball milling, re-pelletized, and heat-treated at 350 °C under nitrogen for 2 hours.

[0027] Example 3 - Preparation of Composite Gel Polymer Electrolyte Using the powder of Example 1, 150 mg of LPS powder was mixed in a mortar and pestle, while 50 mg of a solution was dropped in to obtain a solution containing 19.5% trimethylolpropane ethoxylate triacrylate (Mn~428), 0.5% 2-hydroxy-2-methylpropiophenone, and 1 mol / L lithium bis(trifluoromethanesulfonyl)imide in 80% tetraethylene glycol dimethyl ether. The obtained slurry was coated onto a glass substrate using the doctor blade method or directly onto a polypropylene separator (e.g., Celgard 2400). The layer was cured for 20 minutes using low-power ultraviolet irradiation until the film solidified into a self-standing gel. The flexibility of the film was judged by the powder content. A higher powder content resulted in a harder film, while a lower powder content resulted in a more flexible film. The thickness of the film was controllable, and a typical layer thickness was 20 μm or about 20 μm. The LPS composite gel polymer electrolyte can be seen in Figures 2 and 11, and a scanning electron microscope (SEM) image of the LPS composite gel polymer electrolyte deposited on the surface of the polypropylene separator is shown in Figure 3.

[0028] Example 4 - Plasma Deposition of LPS Film Using the LPS powder of Example 1, 1 g of LPS was pelletized on a copper substrate (thickness 1 millimeter (mm)) at 175 °C and 250 kilonewtons (kN) for 5 minutes using indium foil (0.1 mm) as a binder to obtain a 2-inch sputtering target. The target was then used in a plasma coater under an argon environment to deposit LPS on the substrate. The deposited LPS layer was 200 nanometers (nm) thick after 2 minutes of deposition. Using the sputtered film, it was deposited directly on (1) the anode as anode protection, (2) the separator as an intermediate layer, and / or (3) the cathode to prevent or suppress leakage of ions / intermediate species from the cathode in the battery (e.g., polysulfide in a Li-S battery).

[0029] Example 5 - Measurement of Ionic Conductivity The electrolyte pellet of Example 2 was placed between two stainless steel blocking electrodes and examined using electrochemical impedance spectroscopy between 2 megahertz (MHz) and 0.1 hertz (Hz). The Nyquist plot is shown in Figure 4 and analyzed using an equivalent circuit model that explains the bulk, grain boundary, and interfacial resistance. The ionic conductivity through the bulk of the film, if present, was obtained from the diameter of the semi-circle of the Nyquist plot. The resistance corresponds to Z at 10 - 100 kilohertz. The ionic conductivity was calculated using the following equation. real corresponding to. The ionic conductivity was calculated using the following equation.

Equation

[0030] Example 6 - Use of the Solid Electrolyte in a Li-Ion Battery Using the LPS film of Example 4, a lithium-ion battery was fabricated using lithium iron phosphate (LPF) cathode, lithium metal anode, and LPS (i.e., LPS film) as the electrolyte. The cathode remained impregnated with the liquid electrolyte (1:1 EC:DMC containing 1 M LiPF6). The battery was compared with the liquid electrolyte impregnated in the Celgard separator and the liquid electrolyte impregnated in the LISICON commercial solid electrolyte. The battery was tested for 5 cycles each at the initial cycles of C / 10, C / 5, C / 3, C / 2, 1C, 2C, and 5C, and then cycled indefinitely at 1C. Figure 5 shows the cycle plot of the 1C cycle. The stability of the LPS-containing cell is evident, where the liquid electrolyte showed good initial performance, then rapidly declined after cycle 130 and finally ended around cycle 300. The LISICON cells were not as good, and their capacity fade was at a fast pace from the beginning. The LPS battery (film with a thickness of 120 μm) remained functional and operated for a total of 750 cycles, higher than 50% of the theoretical capacity over nearly 500 cycles and before dropping below 50 mAh / g. The LPF filling amount was 4.85 milligrams per square centimeter (mg / cm 2 ).

[0031] Example 7 - Aqueous Sulfide Lithium and palladium nitrate (LiNO₃ and Pd(NO₃)₂) were used in various molar ratios of 1:1 to 24:1 (Li:Pd), and the sulfur source precursor thiourea was used in a molar ratio of 10:1 (S:Pd) to synthesize LPS powder. In many assemblies, a Li:Pd:S atomic ratio of 4:1:10 was used, the salts and sulfur source were dissolved in water, and then placed in a sealed reactor at 140 °C for 24 hours. When thiourea decomposes to produce sulfides (e.g., especially hydrogen sulfide), the formation of an insoluble ternary compound of LPS occurs by the coprecipitation reaction of lithium sulfide and palladium sulfide. The precipitate was collected by filtration, washed three times with deionized (DI) water, and finally (the fourth time) washed with acetone. Then, the compound was dried under vacuum at 50 °C for 12 hours, followed by calcination at 400 °C for 2 hours under argon, and then stored under argon until further use. Figure 6 is a scanning electron microscope (SEM) image of the obtained dried powder showing nano- and submicron-sized flaky structures. Based on the atomic ratios of the starting precursors, a final product with an atomic ratio of 4:1:2 (Li:Pd:S) was obtained.

[0032] Example 8 - Mechanical Ball Milling Using a ball mill, lithium sulfide (Li₂S) and palladium sulfide (PdS) were mixed in various ratios of 2:1 to 8:1 (Li₂S:PdS) in 45 ml of zirconia and milled for 10 hours at 600 revolutions per minute (rpm) under argon. The recovered compound was washed three times with DI water and finally (the fourth time) washed with acetone. Then, the compound was dried under vacuum at 50 °C for 12 hours, followed by calcination at 400 °C for 2 hours under argon, and then stored under argon until further use. Figure 7 is an SEM image of the obtained powder showing a flaky structure with a submicron thickness.

[0033] Example 9 - Electrochemical Formation Lithium and palladium acetates (C2H3LiO2 and C4H6O4Pd) dissolved in water in a molar ratio of 1:1 to 24:1 (Li:Pd) and thioacetamide were used as a sulfur source at 10:1 (S:Pd). The mixed aqueous solution was impregnated into a glass fiber disk and placed between two aluminum electrodes. The cell was maintained at 80 °C and a constant potential operation at 1 V was carried out for 20 minutes. The negative electrode was coated with the precipitated sulfide, recovered, rinsed with water (e.g., DI water), then rinsed with acetone, and stored under argon for further use.

[0034] Example 10 - Characterization of LPS Compounds The LPS compounds prepared in Examples 7 - 9 were characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The DSC in Figure 8 shows a broad endothermic peak below 100 °C corresponding to the weight loss of absorbed moisture, an endothermic peak around 220 °C corresponding to the weight loss of sulfur, and an exothermic peak around 391 °C corresponding to the crystallization of the compound.

[0035] Referring to Figures 9A and 9B, the XRD pattern shows an amorphous structure of the compound tested after synthesis (Figure 9A). However, after firing at 400 °C under argon for 2 hours, the compound shows a crystalline structure and the peaks are consistent with other palladium sulfide compounds (Figure 9B).

[0036] Example 11 - Membrane Preparation by Pelletization Using dried and fired LPS, the powder (from Examples 7 - 9) was pulverized and pelletized into 0.5-inch pellets at 75 tons. The pellets were then dried at 50 °C under vacuum, fired at 400 °C under argon for 2 hours, and then stored under argon for use as an electrolyte / anode protective layer in a Li-ion battery. Figure 10 shows an image of the fired LPS pellets.

[0037] Example 12 - Membrane Preparation by Vacuum Filtration on a Separator The LPS powders of Examples 7 to 9 were suspended in 75 milliliters (ml) of a tetrahydrofuran solution containing 5% polyvinylpyrrolidone binder using probe sonication. Subsequently, the stable suspension was vacuum filtered on a 12 square centimeter (cm 2 ) polypropylene membrane to obtain a conformal membrane with a controllable milligram per square centimeter (mg / cm 2 ) filling amount according to the mg / ml filling amount of LPS in the solution. Subsequently, the membranes seen in FIGS. 2, 11, and 12 were dried under vacuum at 50 °C and stored under argon for subsequent analysis and use.

[0038] Example 13 - Film fabrication by sputter coating on foil Using dried and calcined LPS, the powder (Examples 7 to 9) was micronized and pelletized into 2-inch pellets at 75 tons. Subsequently, the pellets were dried under vacuum at 50 °C, and then a sputter target was fabricated by fixing the pellets to a copper disk using indium foil as a binder at 160 °C. Subsequently, the obtained sputter target was stored under argon until later use.

[0039] To sputter LPS onto a lithium substrate (e.g., lithium foil), a coating cycle of 30 seconds and then a pause of 30 seconds was used. Different thicknesses of the film were achieved depending on the number of sputter / pause cycles. Typically, a continuous film of about 0.1 μm was obtained by 10 cycles of sputtering. Smoothness and a pure structure of the anode were essential for uniform layer formation.

[0040] Example 14 - Evaluation of electrochemical properties of the film To determine the ionic conductivity of LPS, an LPS pellet was placed between two lithium metal anodes in a Swagelok assembly, and electrochemical impedance spectroscopy data was collected between 2 megahertz (MHz) and 1 hertz (Hz) to obtain the diameter of the high-frequency semi-circle. FIG. 1 shows an image of a pellet having a thickness of about 1 millimeter (mm). The resistance obtained from this diameter was converted to Siemens per centimeter (S.cm-1 It was used to calculate the ionic conductivity σ in [Number] where L is the pellet thickness, A is the pellet area, and Z is the real resistance obtained using the diameter of the semicircle of the high frequency (see Fig. 4). 0.74×10 -3 S.cm -1 The average value was obtained.

[0041] To determine the compatibility between the electrolyte and the lithium metal anode, plating and stripping were performed in a lithium-lithium symmetric test. The symmetric cell had a coated lithium electrode and was compared with a control cell not protected with the LPS layer. Two electrodes were separated using a Celgard separator impregnated with 50:50 ethylene carbonate:dimethyl carbonate (EC:DMC) containing 1 molar / liter (mol / L) lithium hexafluorophosphate (LiPF6). The cell was cycled at a current density of 3 milliamperes per square centimeter (mA / cm 2 ) for 1 hour of plating and 1 hour of stripping (see also Fig. 13).

[0042] Example 15 - LPS film as a solid electrolyte in a battery A lithium-ion battery was fabricated using the LPS film, and the stabilization effect obtained with various battery chemistries at a 1C discharge rate was determined. The batteries were tested with lithium iron phosphate (LFP), nickel cobalt aluminum (NCA), and nickel manganese cobalt (NMC811) cathode materials against a lithium anode. For the LFP cells, LPS pellets with a thickness of 200 μm were used on the anode side, and the capacity retention performance with respect to 1M LiPF6 in the EC:DMC electrolyte was actually examined.

[0043] The battery was fabricated using pellets that cover the lithium anode side, and the cathode side had a polypropylene separator impregnated with 1M LiPF6 in an EC:DMC electrolyte. The pellet battery showed improved capacity retention during cycling at 1C. The battery without the solid electrolyte pellet reached 80% of its initial capacity at cycle 123 and 70% of its initial capacity at cycle 141. When using the solid electrolyte pellet, the 80% capacity retention cycle was 270, and the 70% capacity retention cycle was 307 (see Figure 14). It was also clear that the battery without the solid electrolyte pellet rapidly degraded in performance to almost zero capacity retention, while the pellet-containing battery continued to retain approximately 40% of its capacity even after 500 cycles.

[0044] Lithium sputtered with LPS of approximately 500 nanometers (nm) was used for the lithium anode for the NCA (cathode) battery against lithium (anode) at a 1C discharge rate. The capacity retention of the battery was clearly improved with the coated anode compared to the uncoated anode. The uncoated anode showed 139 cycles to 80% capacity retention and 146 cycles to 70% capacity retention. For the coated anode, capacity retention exceeding 84% was achieved up to 200 cycles (see Figure 15).

[0045] A lithium metal anode and an NMC811 cathode were used with a 1M LiPF6 EC:DMC electrolyte to fabricate a battery using a Celgard polypropylene separator pre-coated with LPS. The battery was cycled at a 1C discharge rate in the range of 2.5 volts (V) to 4.2V. The uncoated Celgard had 232 cycles to 80% capacity retention, 236 cycles to 70% capacity retention, and showed a very rapid capacity decline beyond 200 cycles. The coated Celgard had 334 cycles to 80% capacity decline, 388 cycles to 70% capacity retention, and maintained a relatively slow capacity decline up to at least 500 cycles (see Figure 16).

[0046] These results indicate that the LPS compounds of embodiments of the present invention are very advantageous for lithium anodes in lithium batteries (e.g., as a coating on the anode or as a pellet, or as a coating on a separator covering the anode), regardless of the cathode material.

[0047] The examples and embodiments described herein are for illustrative purposes only, and various modifications or changes thereto will be suggested to those skilled in the art, and those are intended to be included within the spirit and scope of this specification.

[0048] All patents, patent applications, provisional applications, and publications (including those in the "Background Art" section) referred to or cited herein are hereby incorporated by reference in their entirety, including all drawings and tables, to the extent that they do not conflict with the explicit teachings of this specification.

Claims

1. An anode, a cathode, and a solid electrolyte disposed between the anode and the cathode, wherein at least one of the anode and the cathode contains lithium, and the solid electrolyte contains lithium palladium sulfide (LPS), lithium platinum sulfide, lithium rhodium sulfide, lithium iridium sulfide, lithium osmium sulfide, or lithium ruthenium sulfide, a battery.

2. The battery according to claim 1, wherein both the anode and the cathode contain lithium.

3. The battery according to any one of claims 1 to 2, wherein the cathode contains lithium iron phosphate (LFP), nickel cobalt aluminum (NCA), or nickel manganese cobalt (NMC).

4. The battery according to any one of claims 1 to 3, wherein the solid electrolyte has an ionic conductivity exceeding 0.10 millisiemens / cm (mS / cm).

5. The battery according to any one of claims 1 to 4, further comprising a separator disposed between the anode and the cathode, and the solid electrolyte includes a film disposed as an intermediate layer on the separator.

6. The battery according to any one of claims 1 to 5, wherein the solid electrolyte is disposed in the form of a film having a thickness of 20 nanometers (nm) to 100 micrometers (μm).

7. The battery has a capacity higher than 50% of the theoretical capacity after at least 450 1C cycles, the battery has a capacity higher than 80% of the theoretical capacity after at least 200 1C cycles, the battery has a capacity higher than 80% of the theoretical capacity after at least 300 1C cycles, the battery according to any one of claims 1 to 6.

8. The battery further comprises a separator disposed between the anode and the cathode, both the anode and the cathode contain lithium, the solid electrolyte contains lithium palladium sulfide (LPS), the solid electrolyte has an ionic conductivity exceeding 0.10 millisiemens / cm (mS / cm), the solid electrolyte includes a film disposed as an intermediate layer on the separator, the battery is a lithium-ion (Li-ion) battery, a lithium-air (Li-air) battery, or a lithium-sulfur (Li-sulfur) battery, and the solid electrolyte is disposed in the form of a film having a thickness of at least 20 μm. The battery has a capacity higher than 50% of the theoretical capacity after at least 450 1C cycles, The battery has a capacity higher than 80% of the theoretical capacity after at least 200 1C cycles, The battery according to claim 1, having a capacity higher than 80% of the theoretical capacity after at least 300 1C cycles.

9. A method for manufacturing a solid electrolyte, comprising: a step of producing a powder; and a step of producing a solid electrolyte film from the powder, The solid electrolyte contains lithium palladium sulfide (LPS), lithium platinum sulfide, lithium rhodium sulfide, lithium iridium sulfide, lithium osmium sulfide, or lithium ruthenium sulfide, The step of producing the powder includes: a) Dissolving a first salt, a lithium salt, and a sulfur source in a first solvent to form a first solution; Heating the first solution at a first temperature for a first time to precipitate a sulfurized compound containing lithium and a first component from the first salt; and Drying the sulfurized compound at a second temperature for a second time to obtain a powder, The first salt is a palladium salt, a platinum salt, a rhodium salt, an iridium salt, an osmium salt, or a ruthenium salt, The first component is palladium, platinum, rhodium, iridium, osmium, or ruthenium, or b) Dissolving a second salt, a lithium salt, and a sulfur source in a second solvent to form a second solution; Impregnating the second solution into a disk, and disposing the impregnated disk between a positive electrode and a negative electrode to form a first cell; While performing a constant potential operation in the first cell, heating the first cell at a third temperature for a third time to precipitate a sulfurized compound containing lithium and a second component from the second salt on the negative electrode; and Recovering the sulfurized compound from the negative electrode to obtain the powder, The second salt is a palladium salt, a platinum salt, a rhodium salt, an iridium salt, an osmium salt, or a ruthenium salt, The second component is palladium, platinum, rhodium, iridium, osmium, or ruthenium, or c) Using a ball mill, mixing lithium sulfide (Li ２ S) and a second sulfide containing a transition metal to form a ball mill mixed compound; Milling the ball-milled mixed compound at a first speed for a fourth time to form a sulfurized compound containing lithium and a transition metal; and Drying the sulfurized compound at a fourth temperature for a fifth time to obtain a powder, The method comprising any of the steps, wherein the transition metal is palladium, platinum, rhodium, iridium, osmium, or ruthenium.

10. The step of producing the powder includes step a), Step a) further includes the step of recovering the sulfurized compound by a filtration process on the first solution and then washing the sulfurized compound before drying the sulfurized compound. The method according to claim 9.

11. The first salt is a palladium salt, the first component is palladium, and the solid electrolyte contains LPS. The method according to claim 10.

12. Step a) further includes the step of firing the sulfurized compound at a fifth temperature for a sixth time under an inert atmosphere after drying the sulfurized compound. The method according to any one of claims 10 to 11.

13. The step of producing the powder includes step b), Step b) further includes the step of washing the sulfurized compound after recovering the sulfurized compound to obtain the powder. The method according to claim 9.

14. The second salt is a palladium salt, the second component is palladium, and the solid electrolyte contains LPS. The method according to claim 13.

15. The step of producing the powder includes step c), Step c) further includes the step of firing the sulfurized compound at a sixth temperature for a seventh time under an inert atmosphere after drying the sulfurized compound. The method according to claim 9.

16. The transition metal is palladium, and the solid electrolyte contains LPS. The method according to claim 15.

17. Step c) further includes the step of recovering the sulfurized compound and then washing the sulfurized compound before drying the sulfurized compound. The method according to any one of claims 15 to 16.

18. The step of producing the membrane of the solid electrolyte is The step of pulverizing the powder and pelletizing it into pellets, The step of drying the pellets at a seventh temperature for an eighth time, The step of firing the dried pellets at an eighth temperature for a ninth time to obtain a membrane. The method according to any one of claims 9 to 17.

19. The step of producing the membrane of the solid electrolyte is The step of suspending the powder in a third solution using probe sonication to obtain a suspension, The step of vacuum filtering the suspension on a substrate to obtain a membrane. The method according to any one of claims 9 to 17, comprising the step of drying the membrane at a ninth temperature for a tenth period of time to obtain a membrane.

20. The step of fabricating the solid electrolyte membrane comprises: a step of pulverizing the powder and pelletizing it into pellets; a step of drying the pellets at a tenth temperature for an eleventh period of time; a step of fabricating a sputtering target using the pellets; a step of sputtering the sputtering target onto a sputtering substrate to provide the membrane, the method according to any one of claims 9 to 17.

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