Method for increasing ionic conductivity of solid electrolytes in battery cells

Abstract

A method of manufacturing a garnet-based solid electrolyte separator for a battery cell is provided. The method includes coating a garnet-based material powder with aluminum fluoride, the garnet-based material powder initially including a lithium carbonate layer on an outer surface of the garnet-based material powder to produce a fluoride-treated garnet-based material powder. The method further comprises the step of carrying out solid-state reaction on the garnet-based material powder subjected to fluoride treatment, so that aluminum fluoride reacts with the lithium carbonate layer to generate aluminum oxide, carbon dioxide and lithium fluoride. The solid state reaction produces a fluoride-treated and solid state-reacted garnet-based material powder comprising alumina and lithium fluoride. The method further includes sintering a fluoride-treated and solid-state-reacted garnet-based material powder comprising alumina and lithium fluoride. Sintering includes applying pressure to the fluoride-treated and solid state-reacted garnet-based material powder to densify the powder and produce a separator.

Description

[0001] Government Contracts

[0002] This application was made with Government support under Contract No. DOE DE-EE-0008863 awarded by the Department of Energy. The Government has certain rights in this invention. Technical Field

[0003] The present disclosure generally relates to self-healing solid-state battery configurations and methods of making the same. Background Art

[0004] Lithium-ion batteries and lithium metal batteries are ideal for powering electronic devices in the consumer, automotive and aerospace industries due to their relatively high energy density, high power density, no memory effect and long cycle life compared to other rechargeable battery technologies, including lead-acid batteries, nickel-cadmium batteries and nickel-metal hydride batteries.

[0005] The solid-state battery cell includes a solid electrolyte. The solid electrolyte may include a first planar major surface that abuts and contacts a planar major surface of an anode electrode. The solid electrolyte may include a second planar major surface that abuts and contacts a planar major surface of a cathode electrode. Summary of the invention

[0006] A method for manufacturing a garnet-based solid electrolyte separator for a battery cell is provided. The method includes coating a garnet-based material powder with aluminum fluoride, the garnet-based material powder initially including a lithium carbonate layer on the outer surface of the garnet-based material powder to produce a fluoride-treated garnet-based material powder. The method also includes solid-state reacting the fluoride-treated garnet-based material powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide and lithium fluoride. The solid-state reaction produces a fluoride-treated and solid-state-reacted garnet-based material powder containing aluminum oxide and lithium fluoride. The method also includes sintering the fluoride-treated and solid-state-reacted garnet-based material powder containing aluminum oxide and lithium fluoride. Sintering includes applying pressure to the fluoride-treated and solid-state-reacted garnet-based material powder to densify the fluoride-treated and solid-state-reacted garnet-based material powder and produce a garnet-based solid electrolyte separator.

[0007] In some embodiments, the garnet-based material powder includes lithium lanthanum zirconium oxide (LLZO) powder or a doped LLZO powder including aluminum, gallium, niobium, or tantalum as a dopant.

[0008] In some embodiments, alumina acts as a dopant to stabilize the LLZO powder or doped LLZO powder in the cubic phase.

[0009] In some embodiments, coating the garnet-based material powder further comprises coating the garnet-based material powder with GaF3, NbF5, or TaF5.

[0010] In some embodiments, coating the garnet-based material powder includes utilizing atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), a solution method, or mixing the garnet-based material powder with a dry powder of a nano-sized fluoride, including AlF3, GaF3, NbF3, or TaF5.

[0011] In some embodiments, sintering further comprises utilizing lithium fluoride as a sintering aid to achieve a relatively low minimum temperature during the sintering process.

[0012] In some embodiments, sintering further comprises applying increasing pressure to the fluoride treated and solid state reacted garnet-based material powder over time.

[0013] In some embodiments, conducting a solid state reaction comprises heating the fluoride-treated garnet-based material powder to a temperature not exceeding 500°C.

[0014] In some embodiments, sintering further comprises heating the fluoride treated and solid state reacted garnet-based material powder to a temperature of 1050° C. at a pressure of 80 MPa for 1 hour.

[0015] In some embodiments, sintering further comprises hot pressing the fluoride treated and solid state reacted garnet-based material powder into pellets at a pressure of at least 10 MPa.

[0016] In some embodiments, the method further includes, after sintering, pairing residual lithium carbonate or newly formed, sintered lithium carbonate with lithium fluoride and generating a space charge configured to facilitate diffusion of lithium ions through grain boundaries of the garnet-based solid electrolyte separator.

[0017] In some embodiments, the solid electrolyte separator includes grain boundaries comprising a mixture of LiF and Li2CO3 or a mixture of LiF and LiAlO2.

[0018] According to an alternative embodiment, a method for manufacturing a solid electrolyte separator for a battery cell is provided. The method includes manufacturing a solid electrolyte separator, which includes coating an LLZO powder with aluminum fluoride, the LLZO powder initially including a lithium carbonate layer on the outer surface of the LLZO powder to produce a fluoride-treated LLZO powder. Manufacturing the separator also includes solid-state reaction of the fluoride-treated LLZO powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide and lithium fluoride. The solid-state reaction produces a fluoride-treated and solid-state-reacted LLZO powder containing aluminum oxide and lithium fluoride. Manufacturing the separator also includes sintering the fluoride-treated and solid-state-reacted LLZO powder containing aluminum oxide and lithium fluoride. Sintering includes applying pressure to the fluoride-treated and solid-state-reacted LLZO powder to densify the fluoride-treated and solid-state-reacted LLZO powder and produce a solid electrolyte separator. The method also includes manufacturing a battery cell, including disposing an anode and a cathode in a housing, and disposing a solid electrolyte separator between and in contact with the anode and the cathode. Alumina acts as a dopant to stabilize the LLZO powder in the cubic phase.

[0019] In some embodiments, coating the LLZO powder further comprises coating the LLZO powder with GaF3, NbF5, or TaF5.

[0020] In some embodiments, sintering further comprises utilizing lithium fluoride as a sintering aid to achieve a relatively low minimum temperature during the sintering process.

[0021] In some embodiments, sintering further comprises applying increasing pressure to the fluoride treated and solid state reacted LLZO powder over time.

[0022] In some embodiments, conducting a solid state reaction comprises heating the fluoride-treated LLZO powder to a temperature not exceeding 500°C.

[0023] In some embodiments, sintering further comprises heating the fluoride treated and solid state reacted LLZO powder to a temperature of 1050° C. at a pressure of 80 MPa for 1 hour.

[0024] In some embodiments, sintering further comprises hot pressing the fluoride treated and solid state reacted LLZO powder into pellets at a pressure of at least 10 MPa.

[0025] According to an alternative embodiment, a solid electrolyte separator for a battery cell is provided. The solid electrolyte separator includes a solid electrolyte separator produced by coating a garnet-based material powder with aluminum fluoride, the garnet-based material powder initially including a lithium carbonate layer on the outer surface of the garnet-based material powder to produce a fluoride-treated garnet-based material powder. The solid electrolyte separator is also produced by solid-state reaction of the fluoride-treated garnet-based material powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide and lithium fluoride. The solid-state reaction produces a fluoride-treated and solid-state-reacted garnet-based material powder containing aluminum oxide and lithium fluoride. The solid electrolyte separator is also produced by sintering the fluoride-treated and solid-state-reacted garnet-based material powder containing aluminum oxide and lithium fluoride. Sintering includes applying pressure to the fluoride-treated and solid-state-reacted garnet-based material powder to densify the fluoride-treated and solid-state-reacted garnet-based material powder and produce a solid electrolyte separator.

[0026] The present invention discloses the following technical solutions.

[0027] Scheme 1. A method for manufacturing a garnet-based solid electrolyte separator for a battery cell, the method comprising:

[0028] coating a garnet-based material powder, the garnet-based material powder initially comprising a lithium carbonate layer on an outer surface of the garnet-based material powder, with aluminum fluoride to produce a fluoride-treated garnet-based material powder;

[0029] solid-state reacting the fluoride-treated garnet-based material powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide, and lithium fluoride, wherein the solid-state reaction produces a fluoride-treated and solid-state-reacted garnet-based material powder comprising aluminum oxide and lithium fluoride; and

[0030] A fluoride-treated and solid-state-reacted garnet-based material powder comprising aluminum oxide and lithium fluoride is sintered, wherein the sintering includes applying pressure to the fluoride-treated and solid-state-reacted garnet-based material powder to densify the fluoride-treated and solid-state-reacted garnet-based material powder and produce a garnet-based solid electrolyte separator.

[0031] Option 2. A method according to Option 1, wherein the garnet-based material powder comprises lithium lanthanum zirconium oxide (LLZO) powder or a doped LLZO powder containing aluminum, gallium, niobium or tantalum as a dopant.

[0032] Option 3. The method according to Option 1, wherein the aluminum oxide acts as a dopant to stabilize the LLZO powder or doped LLZO powder in a cubic phase.

[0033] Option 4. A method according to Option 1, wherein coating the garnet-based material powder also includes coating the garnet-based material powder with GaF3, NbF5 or TaF5.

[0034] Option 5. A method according to Option 1, wherein coating the garnet-based material powder includes utilizing atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), a solution method or mixing the garnet-based material powder with a nano-sized fluoride, including dry powder of A1F3, GaF3, NbF3 or TaF5.

[0035] Option 6. A method according to Option 1, wherein the sintering also includes using the lithium fluoride as a sintering aid to achieve a relatively low minimum temperature during the sintering process.

[0036] Option 7. A method according to Option 1, wherein sintering also includes applying increasing pressure to the fluoride-treated and solid-state reacted garnet-based material powder over time.

[0037] Option 8. A method according to Option 1, wherein conducting a solid-state reaction includes heating the fluoride-treated garnet-based material powder to a temperature not exceeding 500°C.

[0038] Option 9. A method according to Option 1, wherein sintering further comprises heating the fluoride-treated and solid-state-reacted garnet-based material powder to a temperature of 1050° C. at a pressure of 80 MPa for 1 hour.

[0039] Option 10. A method according to Option 1, wherein sintering also includes hot pressing the fluoride-treated and solid-state-reacted garnet-based material powder into pellets at a pressure of at least 10 MPa.

[0040] Option 11. A method according to Option 1, which also includes, after sintering, pairing the residual lithium carbonate or the newly formed sintered lithium carbonate with lithium fluoride and generating a space charge configured to promote the diffusion of lithium ions through the grain boundaries of the garnet-based solid electrolyte separator.

[0041] Option 12. The method according to Option 1, wherein the solid electrolyte separator includes grain boundaries containing a mixture of LiF and Li2CO3 or a mixture of LiF and LiAlO2.

[0042] Embodiment 13. A method of manufacturing a solid electrolyte separator for a battery cell, the method comprising:

[0043] A solid electrolyte separator is manufactured, comprising:

[0044] coating a LLZO powder, the LLZO powder initially comprising a lithium carbonate layer on an outer surface of the LLZO powder, with aluminum fluoride to produce a fluoride-treated LLZO powder;

[0045] solid-state reacting the fluoride-treated LLZO powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide, and lithium fluoride, wherein the solid-state reaction produces a fluoride-treated and solid-state-reacted LLZO powder comprising aluminum oxide and lithium fluoride; and

[0046] sintering a fluoride-treated and solid-state-reacted LLZO powder comprising aluminum oxide and lithium fluoride, wherein the sintering comprises applying pressure to the fluoride-treated and solid-state-reacted LLZO powder to densify the fluoride-treated and solid-state-reacted LLZO powder and produce a solid electrolyte separator; and

[0047] Manufacturing a battery cell, comprising:

[0048] disposing the anode and cathode within the housing; and

[0049] disposing a solid electrolyte separator between and in contact with the anode and the cathode; and

[0050] Alumina acts as a dopant to stabilize the LLZO powder in the cubic phase.

[0051] Option 14. A method according to Option 13, wherein coating the LLZO powder also includes coating the LLZO powder with GaF3, NbF5 or TaF5.

[0052] Option 15. A method according to Option 13, wherein the sintering also includes using lithium fluoride as a sintering aid to achieve a relatively low minimum temperature during the sintering process.

[0053] Option 16. A method according to Option 13, wherein sintering also includes applying increasing pressure to the fluoride-treated and solid-state-reacted LLZO powder over time.

[0054] Option 17. A method according to Option 13, wherein performing a solid-state reaction comprises heating the fluoride-treated LLZO powder to a temperature not exceeding 500°C.

[0055] Option 18. A method according to Option 13, wherein sintering further comprises heating the fluoride-treated and solid-state-reacted LLZO powder to a temperature of 1050° C. at a pressure of 80 MPa for 1 hour.

[0056] Option 19. A method according to Option 13, wherein sintering also includes hot pressing the fluoride-treated and solid-state-reacted LLZO powder into pellets at a pressure of at least 10 MPa.

[0057] Embodiment 20. A solid electrolyte separator for a battery cell, comprising:

[0058] A solid electrolyte separator manufactured by:

[0059] coating a garnet-based material powder, the garnet-based material powder initially comprising a lithium carbonate layer on an outer surface of the garnet-based material powder, with aluminum fluoride to produce a fluoride-treated garnet-based material powder;

[0060] solid-state reacting the fluoride-treated garnet-based material powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide, and lithium fluoride, wherein the solid-state reaction produces a fluoride-treated and solid-state-reacted garnet-based material powder comprising aluminum oxide and lithium fluoride; and

[0061] A fluoride treated and solid state reacted garnet-based material powder comprising aluminum oxide and lithium fluoride is sintered, wherein the sintering includes applying pressure to the fluoride treated and solid state reacted garnet-based material powder to densify the fluoride treated and solid state reacted garnet-based material powder and produce a solid electrolyte separator.

[0062] The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 A side cross-sectional view of an exemplary battery cell including an anode, a cathode, and a solid electrolyte separator according to the present disclosure is schematically illustrated.

[0064] Figure 2 Schematically illustrates the manufacturing method according to the present disclosure. Figure 1 A method for manufacturing a solid electrolyte separator;

[0065] Figure 3 It is a diagram illustrating the manufacturing method according to the present disclosure. Figure 1 A flow chart of a method of a solid electrolyte separator; and

[0066] Figure 4 is a diagram illustrating a method of manufacturing a solid electrolyte separator according to the present disclosure. Figure 1 A flow chart of a method of producing a battery pack. DETAILED DESCRIPTION

[0067] The battery system may include one or more solid-state battery cells.The solid-state battery cell may include an anode electrode, a cathode electrode, and a solid electrolyte.

[0068] Solid-state batteries include a solid electrolyte that provides or facilitates ion transfer between the anode electrode and the cathode electrode. The solid electrolyte also acts as a physical separator between the anode electrode and the cathode electrode, thereby preventing internal short circuits within the battery.

[0069] Solid-state batteries may face challenges. Solid-state batteries generate stress at the interface due to volume changes in the anode and cathode during charge and discharge. As the various layers of the battery cell cycle between charge and discharge cycles, the contact area between the layers can be lost due to the mismatch between the mechanical properties of adjacent layers. Interfacial delamination can also result. The pressure of the electrode stack that clamps the layers together can alleviate the interfacial delamination between the solid electrolyte (SE) separator layer and the electrode, but it is more difficult to recover the contact loss in the cathode perpendicular to the direction of the pressure.

[0070] Lithium lanthanum zirconium oxide (Li7La3Zr2O 12 LLZO (garnet-based oxide solid electrolyte) is a promising candidate for solid electrolytes due to its high ionic conductivity and chemical stability to lithium (Li) metal. LLZO is an example of garnet-based oxide solid electrolyte.

[0071] LLZO is sensitive to moisture and air, and it is easy to form a lithium carbonate (Li2CO3) layer on the surface of LLZO particles, which impairs the ionic conductivity of LLZO. The Li2CO3 layer formed on the surface of LLZO causes high interfacial impedance. LLZO reacts with moisture in the ambient air within a few minutes to form a Li2CO3 passivation layer.

[0072] LLZO has two phases. The ionic conductivity of the high-temperature cubic phase is two orders of magnitude higher than that of the tetragonal phase. The cubic phase may be unstable at relatively low temperatures, such as room temperature. Dopants, such as aluminum oxide (Al2O3), can be used to stabilize the high-temperature cubic phase and provide higher ionic conductivity at relatively low temperatures.

[0073] The method in the art includes mixing Al2O3 powder with LLZO, doping using a solid-state reaction at high temperature, pressing the reacted LLZO into pellets, pre-sintering the pellets to remove lithium carbonate before sintering, and sintering the pellets at a temperature above 1000° C. This method used in the art is time-consuming and expensive.

[0074] A method for removing lithium carbonate formed on a garnet-based solid electrolyte (e.g., LLZO) at a relatively low temperature and doping aluminum into LLZO to stabilize the cubic phase is provided. Other dopants may include gallium, niobium, or tantalum. In addition, a sintering aid is used to accelerate the sintering process of LLZO and enhance the ionic conductivity of LLZO. In the disclosed method, aluminum fluoride and other fluorides (e.g., GaF3, NbF5, and / or TaF5) may be deposited on the surface of LLZO particles by atomic layer deposition, vapor deposition, mixing commercial aluminum fluoride nanoparticles with LLZO powder, or wet chemical methods. The thickness of the fluoride layer applied to LLZO may depend on the thickness or amount of lithium carbonate present. The fluoride coating is hydrophobic and can prevent LLZO from reacting with moisture in the air. The fluoride-treated LLZO is then subjected to a solid-state reaction and then sintered.

[0075] The disclosed method can be described as comprising two steps. First, the method comprises preparing fluoride-treated LLZO and removing lithium carbonate from LLZO using a solid-state reaction. The solid-state reaction can be carried out at a relatively low temperature, for example, below 500°C. The solid-state reaction further produces alumina that stabilizes the cubic phase of LLZO and lithium fluoride (LiF) as a sintering aid.

[0076] LLZO in a particle sample can exist in multiple phases. LLZO can be formed from a precursor material through a calcination process. Depending on the temperature of the calcination process or a subsequent process, the LLZO sample can include some or all cubic phase LLZO particles. When LLZO cools from a higher temperature, it may naturally transform away from the cubic phase. Modifiers present in accordance with the present disclosure, such as aluminum dopants, can increase the proportion of LLZO particles that remain in the cubic phase.

[0077] Secondly, the method includes sintering the fluoride-treated and solid-state-reacted LLZO containing aluminum oxide and lithium fluoride at a relatively high temperature. The sintering step may include heating the fluoride-treated and solid-state-reacted LLZO to a minimum temperature of 1050°C at 80 megapascals (MPa) for 1 hour. The minimum temperature of the sintering process can be reduced by the presence of a sintering aid, such as LiF. During the sintering process, the pressure can be gradually increased to densify the resulting solid electrolyte.

[0078] Depending on the presence and amount of hydrophobic fluoride, additional lithium carbonate may be formed during subsequent processing after the sintering process. This sintered lithium carbonate pairs with LiF and forms space charge, which can promote lithium ion diffusion across grain boundaries in the solid electrolyte.

[0079] The chemical formula of the solid-state reaction can be described by the following formula 1

[0080] 2AlF3+3Li2CO3→Al2(CO3)3+6LiF→Al2O3+3CO2+6LiF [1]

[0081] Aluminum fluoride and lithium carbonate react to form aluminum carbonate and lithium fluoride. The aluminum carbonate then decomposes to form aluminum oxide and carbon dioxide. The aluminum carbonate present on the fluoride treated and solid state reacted LLZO acts as a dopant to stabilize the LLZO in the cubic phase. In addition, Al2O3 can react with lithium to form LiAlO2. The lithium fluoride present on the fluoride treated and solid state reacted LLZO acts as a sintering aid in the subsequent sintering method step.

[0082] As part of the sintering process step, the powder is densified into pellets using a hot pressing method. In one embodiment, the hot pressing method can use a pressure of more than 10 MPa for densification. At the end of the sintering process step, the pellets can be slowly cooled to retain the cubic phase of LLZO. The final product can include grain boundaries containing a mixture of LiF and Li2CO3 and / or LiF and LiAlO2.

[0083] A variety of methods are contemplated for converting the sintered powder disclosed herein into a solid electrolyte separator. In an exemplary embodiment, the two-step method includes heat treating the sintered powder in a first step. The LLZO powder is cold pressed into pellets at 80 MPa in a stainless steel mold with a diameter of 2.54 cm. The cold-pressed pellets are placed on a magnesium oxide (MgO) crucible under argon and oxygen in a tube furnace. The cold-pressed pellets are calcined at 450°C for 4 hours and then at 850°C for 4 hours. After calcination, the pellets are crushed with an agate mortar and pestle in a glove box. In the second step, the powder obtained in the first step is subjected to rapid induction hot pressing. Al-LLZO powder and / or AlF3-LLZO powder are hot pressed at 1050°C and a constant pressure of 80 MPa for 1 hour in flowing argon using rapid induction hot pressing (RIHP). After RIHP, each billet is cut into pellets using a diamond saw. The pellets were mounted on a grinding fixture with crystal bond wax and ground with sandpaper of 500 to 2500 grit in a glove box. The resulting product can form a solid electrolyte separator.

[0084] According to an alternative embodiment, a battery cell is provided that includes a LLZO solid electrolyte separator manufactured according to the disclosed method. In another embodiment, a device is provided that includes an exemplary vehicle, ship, aircraft, power generation system, or construction equipment that includes a battery cell that includes a LLZO solid electrolyte separator manufactured according to the disclosed method.

[0085] The methods and processes described herein describe steps performed on LLZO material in preparation for use as the primary material in a solid electrolyte separator in a battery cell. Similar methods and processes can be used with other garnet-type materials used as solid electrolyte separators. When describing LLZO powder, a garnet-based material powder may be described instead.

[0086] Figure 1 A side cross-sectional view of an exemplary battery cell including a battery cell 10 is schematically illustrated, the battery cell 10 including an anode 20, a cathode 30, and a solid electrolyte separator 40. The anode 20 includes a current collector 22 and an anode electrode 24. The cathode 30 includes a current collector 32 and a cathode electrode 34. According to the methods disclosed herein, the solid electrolyte separator 40 is constructed of a garnet-based material, such as LLZO. The anode 20 and the cathode 30 are disposed in a housing 50. The solid electrolyte separator 40 is disposed between the anode 20 and the cathode 30. The solid electrolyte separator 40 provides a physical separation of the anode 20 from the cathode 30. The solid electrolyte separator 40 also promotes ion transfer between the anode 20 and the cathode 30. The disclosed method for manufacturing the solid electrolyte separator 40 provides excellent ionic conductivity for the battery cell 10. In some embodiments, the ionic conductivity of the battery cell 10 can be an order of magnitude better than similar battery cells manufactured by methods used in the art.

[0087] The disclosed solid electrolyte separator 40 can be used in a variety of battery cells 10, including prismatic can battery cells, cylindrical battery cells, jelly roll electrode battery cells, and button cell batteries.

[0088] Figure 2 Schematic diagram of the manufacturing Figure 1A method 100 for manufacturing a solid electrolyte separator 40 of the present invention is provided. A coating operation 110 is illustrated, in which a garnet-based material powder 102 containing an exemplary LLZO powder is provided as a first input material. The second and third input materials are illustrated as aluminum fluoride 104 and a second fluoride 106. The second fluoride may include GaF3, NbF5 and / or TaF5. The coating operation 110 may include atomic layer deposition, vapor deposition, mixing commercial aluminum fluoride nanoparticles with LLZO powder, or a wet chemical method. The coating operation 110 provides an output stream of fluoride-treated LLZO powder 112. The solid-state reaction operation 120 is illustrated as receiving the fluoride-treated LLZO powder 112. The fluoride-treated LLZO powder 112 is heated to a temperature not exceeding 500° C. to perform the chemical reaction of Formula 1. The solid-state reaction operation 120 provides an output stream of fluoride-treated and solid-state-reacted LLZO powder 122 containing aluminum oxide and lithium fluoride. The sintering operation 130 is illustrated, which receives a fluoride-treated and solid-state-reacted LLZO powder 122 containing aluminum oxide and lithium fluoride. The fluoride-treated and solid-state-reacted LLZO powder 122 containing aluminum oxide and lithium fluoride is sintered at a temperature of at least the lowest temperature of the sintering operation 130. Further, pressure is applied to the fluoride-treated and solid-state-reacted LLZO powder 122 containing aluminum oxide and lithium fluoride during the sintering process. The sintering operation 130 allows the sintered material to cool at a relatively slow rate. The sintering operation 130 provides a solid electrolyte separator 40 or a material that can be used to form a solid electrolyte separator 40 as an output. The manufacturing method 100 is exemplary. Many additional and / or alternative operations are contemplated, and the present disclosure is not intended to be limited to the examples provided herein.

[0089] Figure 3 Is a diagram illustrating the manufacturing Figure 1Flowchart of method 200 for forming a solid electrolyte separator 40 of a garnet-based material. Method 200 begins at step 202. In step 204, a garnet-based material powder is coated with aluminum fluoride and one or more additional fluorides to produce a fluoride-treated garnet-based material powder. As described herein, the garnet-based material powder initially includes a lithium carbonate passivation layer produced by the reaction of air with the garnet-based material powder on the outer surface of the garnet-based material powder. In step 206, the fluoride-treated garnet-based material powder is solid-state reacted. Aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide and lithium fluoride. As a result of step 206, a fluoride-treated and solid-state-reacted garnet-based material powder containing aluminum oxide and lithium fluoride is produced. In step 208, the fluoride-treated and solid-state-reacted garnet-based material powder containing aluminum oxide and lithium fluoride is sintered. Sintering includes applying pressure to the fluoride-treated and solid-state-reacted garnet-based material powder to densify the fluoride-treated and solid-state-reacted garnet-based material powder. At step 210, a garnet-based solid electrolyte separator is manufactured using the sintered material powder. At step 212, method 200 ends. Method 200 is provided as an exemplary method for manufacturing a solid electrolyte separator 40. Many additional and / or alternative method steps are contemplated, and the present disclosure is not intended to be limited to the examples provided herein.

[0090] Figure 4 is a diagram illustrating the manufacture of a method including a solid electrolyte separator 40 Figure 1 Flow chart of method 300 for battery pack battery 10. Method 300 begins at step 302. At step 304, according to Figure 3 The method 200 produces a solid electrolyte separator 40. In step 306, the electrolyte separator 40 is disposed on Figure 1 At step 308, the anode 20, the solid electrolyte separator 40, and the cathode 30 are disposed in the housing 50 of the battery cell 10. At step 310, the method 300 ends. The method 300 is provided as a method for manufacturing Figure 1 Numerous additional and / or alternative method steps are contemplated, and the present disclosure is not intended to be limited to the examples provided herein.

[0091] While the best modes for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments for practicing the disclosure within the scope of the appended claims.

Claims

1. A method of manufacturing a garnet-based solid electrolyte separator for a battery cell, the method comprising: coating a garnet-based material powder, the garnet-based material powder initially comprising a lithium carbonate layer on an outer surface of the garnet-based material powder, with aluminum fluoride to produce a fluoride-treated garnet-based material powder; solid-state reacting the fluoride-treated garnet-based material powder so that the aluminum fluoride reacts with the lithium carbonate layer to produce aluminum oxide, carbon dioxide, and lithium fluoride, wherein the solid-state reaction produces a fluoride-treated and solid-state-reacted garnet-based material powder comprising aluminum oxide and lithium fluoride; and A fluoride-treated and solid-state-reacted garnet-based material powder comprising aluminum oxide and lithium fluoride is sintered, wherein the sintering includes applying pressure to the fluoride-treated and solid-state-reacted garnet-based material powder to densify the fluoride-treated and solid-state-reacted garnet-based material powder and produce a garnet-based solid electrolyte separator. 2 . The method according to claim 1 , wherein the garnet-based material powder comprises lithium lanthanum zirconium oxide (LLZO) powder or a doped LLZO powder containing aluminum, gallium, niobium or tantalum as a dopant. 3 . The method of claim 1 , wherein the aluminum oxide acts as a dopant to stabilize the LLZO powder or the doped LLZO powder in a cubic phase.

4. The method of claim 1, wherein coating the garnet-based material powder further comprises coating the garnet-based material powder with GaF3, NbF5, or TaF5.

5. The method of claim 1, wherein coating the garnet-based material powder comprises utilizing atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), a solution method, or mixing the garnet-based material powder with a dry powder of a nano-sized fluoride, including AlF3, GaF3, NbF3, or TaF5.

6. The method of claim 1, wherein sintering further comprises utilizing the lithium fluoride as a sintering aid to achieve a relatively low minimum temperature during sintering.

7. The method of claim 1, wherein sintering further comprises applying increasing pressure to the fluoride treated and solid state reacted garnet-based material powder over time.

8. The method of claim 1, wherein conducting a solid state reaction comprises heating the fluoride-treated garnet-based material powder to a temperature not exceeding 500°C.

9. The method of claim 1, wherein sintering further comprises heating the fluoride treated and solid state reacted garnet-based material powder to a temperature of 1050°C at a pressure of 80 MPa for 1 hour.

10. The method of claim 1, wherein sintering further comprises hot pressing the fluoride treated and solid state reacted garnet-based material powder into pellets at a pressure of at least 10 MPa.

Images