Patent Application
20240283009
This application claims the benefit of Chinese Patent Application No. 202310179184.1, filed on Feb. 16, 2023. The entire disclosure of the application referenced above is incorporated herein by reference.
The information provided in this section is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
The present disclosure relates to battery cells, and more particularly to a sulfide-based electrolyte layer supported by a dry process electrode layer.
Electric vehicles (EVs) such as battery electric vehicles (BEVs), hybrid vehicles, and/or fuel cell vehicles include one or more electric machines and a battery system including one or more battery cells, modules and/or packs. A power control system is used to control charging and discharging of the battery system during charging and/or driving. Manufacturers of EVs are pursuing increased power density to increase the range of the EVs.
Solid-state batteries (SSBs) with solid electrolyte and SSBs with sulfide electrolyte have the potential to be superior to lithium-ion batteries (LIBs) in terms of abuse tolerance, working temperature range and system design.
A method for preparing an electrolyte layer supported by a dry process electrode layer, the method includes providing a sulfide electrolyte layer; providing a first dry process electrode layer; arranging a first side of the sulfide electrolyte layer adjacent to a first side of the first dry process electrode layer; and calendaring the sulfide electrolyte layer and the first dry process electrode layer to reduce a thickness of the sulfide electrolyte layer to a predetermined thickness in a range from approximately 5 micrometers (μm) to approximately 50 μm.
In other features, providing the sulfide electrolyte layer comprises preparing a mixture of a sulfide electrolyte and polytetrafluoroethylene (PTFE) binder to create the sulfide electrolyte layer; and calendaring the mixture one or more times to reduce a thickness of the sulfide electrolyte layer.
In other features, the sulfide electrolyte comprises 90 wt % to 99.9 wt % and the PTFE binder comprises 0.1 wt % to 10 wt % of the sulfide electrolyte layer. Providing the first dry process electrode layer comprises preparing a mixture of a sulfide electrolyte, active material, a conductive additive, and PTFE binder to create the sulfide electrolyte layer; and calendaring the mixture one or more times to reduce a thickness of the first dry process electrode layer.
In other features, the sulfide electrolyte comprises 10 wt % to 30 wt %, the active material comprises 50 wt % to 90 wt %, the conductive additive comprises 0 wt % to 10 wt %, and the PTFE binder comprises greater than 0 wt % and less than or equal to 10 wt % of the dry process electrode layer. The active material comprises cathode active material. The method of claim 6, wherein the cathode active material is selected from a group consisting of rock salt layered oxide, spinel, a polyanion cathode material, lithium transition-metal oxides, and lithiated metal oxide/sulfide.
In other features, the active material comprises anode active material. The anode active material is selected from a group consisting of carbonaceous material, silicon, silicon and graphite, Li4Ti5O12, a transition-metal, metal oxide/sulfide, Li metal, and Li alloy. The sulfide electrolyte is selected from a group consisting of pseudobinary sulfide, pseudoternary sulfide, pseudoquaternary sulfide, halide-based solid electrolyte, and hydride-based solid electrolyte. The conductive additive is selected from a group consisting of carbon black, graphite, graphene, graphene oxide, Super P, acetylene black, carbon nanofibers, and carbon nanotubes.
In other features, prior to calendaring, the method includes arranging a second dry process electrode layer adjacent to a second side of the sulfide electrolyte layer. The first dry process electrode layer comprises a cathode electrode layer. The second dry process electrode layer comprises an anode electrode layer.
In other features, the method includes attaching the sulfide electrolyte layer and the first dry process electrode layer to a current collector using an electrically conductive adhesive. The electrically conductive adhesive comprises a polymer and an electrically conductive filler. The polymer is selected from a group consisting of epoxy, polyimide, polyester, vinyl ester, polyvinylidene fluoride (PVDF), polyamide, silicone, and acrylic. The conductive filler is selected from a group consisting of Super P, carbon black, graphene, carbon nanotubes, carbon nanofibers, and metal powder.
In other features, a second side of the sulfide electrolyte layer is arranged on a substrate. The substrate comprises polyethylene terephthalate (PET). The method includes attaching one side of a first one of the first dry process electrode layer and the sulfide electrolyte layer to a first side of a current collector using an electrically conductive adhesive. The method includes attaching one side of a second one of the first dry process electrode layer and the sulfide electrolyte layer to a second side of the current collector using an electrically conductive adhesive.
Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
In the drawings, reference numbers may be reused to identify similar and/or identical elements.
While the battery cells are described herein in the context of EVs, the battery cells can be used in stationary applications, non-vehicle applications, and in other applications.
Sulfide electrolyte film may be prepared using a dry process sulfide electrolyte powder. The sulfide electrolyte film prepared in this manner typically has a thickness in a range from 500 micrometers (μm) to 1000 μm. While ensuring long-term cycling ability, the thickness of the sulfide electrolyte film decreases energy density and power capability.
When using a wet slurry process for the sulfide electrolyte film, the thickness can be reduced to 65 μm (e.g., using Li6PS5Cl powder, polyethylene oxide (PEO) binder, LiClO4 and SiO2). Although the PEO binder helps to form the sulfide electrolyte film, mechanical imperfections or failures occur due its limited bonding effect. Breakage of sulfide electrolyte film may occur when microstructural defects or voids are formed during cold-pressing.
Free-standing sulfide-based electrolyte membranes can be produced by multiple calendaring steps with a decreasing gap. The sulfide electrolyte film has good film forming properties and a high film elongate rate due to the fibrillating polymer. However, further reducing the thickness of electrolyte membrane to less than 50 μm by calendaring may provide poor efficiency since an angle α of the rollers is close to zero as the thickness of the film is reduced. A resulting ultra-thin free-standing membrane may be fragile and be very hard to handle.
In some examples, a thin sulfide electrolyte layer (approximately 5 μm to 50 μm, e.g., approximately 25.8 μm where the term approximately means +/−10%) according to the present disclosure is achieved by a roll-to-roll calendaring of electrode dry film and sulfide electrolyte dry film. Polytetrafluoroethylene (PTFE) binder in an electrode film and a sulfide electrolyte layer may provide good film forming properties and a high film elongation rate due to the fibrillating nature of the PTFE. With the help of the supportive dry electrode layer, the thickness of the sulfide electrolyte layer can be reduced. The thin sulfide electrolyte membrane provides an effective strategy for constructing a high-power solid-state battery.
In some examples, a thin PTFE-based sulfide electrolyte layer (e.g., less than 30 μm) can be achieved by roll-to-roll calendaring with the help of the supportive dry cathode membrane as described herein, which increases energy density of the resulting solid-state battery. The dual layer structure shows good mechanical strength.
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The PTFE-based sulfide electrolyte layer 100 increases favorable ion transfer between the cathode and anode electrodes. In some examples, the PTFE-based sulfide electrolyte layer 100 has a thickness in a range from approximately 2 μm to approximately 30 μm (e.g., approximately 20 μm). In some examples, the PTFE-based sulfide electrolyte layer 100 includes or consists of sulfide electrolyte and a PTFE binder. In some examples, the sulfide electrolyte includes approximately 90 wt % to 99.9 wt %, and the PTFE binder includes approximately 0.1 wt % to 10 wt %, e.g., <2 wt %). In various implementations, the sum of wt % of the sulfide electrolyte and the PTFE binder equals 100 wt %.
The dry process cathode electrode layer 110 provides mechanical strength for the thin sulfide electrolyte layer to be rolled, handled, and unrolled within an electrode fabrication process. In some examples, the dry process cathode electrode layer 110 has a thickness in a range from approximately 50 μm to approximately 300 μm, (e.g., approximately 200 μm). In some examples, the dry process cathode electrode layer 110 includes or consists of sulfide electrolyte, cathode active material, conductive adhesive, and PTFE binder. In some examples, the sulfide electrolyte includes approximately 10 wt % to 30 wt %, the cathode active material includes approximately 50 wt % to 90 wt %, the conductive additives include approximately 0 wt % to 10 wt %, and the PTFE binder includes approximately greater than 0 wt % and less than or equal to 10 wt % (e.g., greater than 0% and less than 1 wt %). In various implementations, the sum of wt % of the sulfide electrolyte, the cathode active material, the conductive additives, and the PTFE binder equals 100 wt %.
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The solid electrolyte layer 380 builds up favorable ion transfer between cathode and anode electrodes. In some examples, the solid electrolyte layer 380 has a thickness in a range of approximately 2 μm to approximately 30 μm (e.g., approximately 20 μm). The solid electrolyte layer 380 includes or consists of sulfide electrolyte and PTFE binder. In some examples, the sulfide electrolyte is in a range from 90 wt % to 99.9 wt % and the PTFE binder is in a range from 0.1 wt % to 10 wt % (e.g., less than 2 wt %). In various implementations, the sum of wt % of the sulfide electrolyte and the PTFE binder equals 100 wt %.
The dry process anode electrode layer 390 provides mechanical strength for the thin sulfide electrolyte layer 380 to be rolled, handled, and unrolled within an electrode fabrication process. In some examples, a thickness of the dry process anode electrode layer 390 is in a range from approximately 50 μm to approximately 150 μm (e.g., approximately 100 μm).
The dry process anode electrode layer 390 includes sulfide electrolyte, anode active material, conductive additive, and PTFE binder. In some examples, the sulfide electrolyte includes or consists of 10 wt % to 30 wt %, the anode active material comprises 50 wt % to 90 wt %, the conductive additives 0 wt % to 10 wt %, and the PTFE binder comprises greater than 0 wt % and less than or equal to 10 wt % (e.g., less than 1 wt %). In various implementations, the sum of wt % of the sulfide electrolyte, the anode active material, the conductive additives, and the PTFE binder equals 100 wt %.
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In some examples, the dry process cathode electrode layer 410 has a thickness after the calendaring in a range from 50 μm to 300 μm (e.g., 200 μm). The dry process cathode electrode layer 410 may include or consist of sulfide electrolyte, cathode electrode material, conductive additives, and PTFE binder. In some examples, the sulfide electrolyte includes approximately 10 wt % to 30 wt %, the cathode active material includes approximately 50 wt % to 90 wt %, the conductive additives include approximately 0 wt % to 10 wt %, and the PTFE binder includes greater than 0 wt % and less than or equal to 10 wt % (e.g., greater than 0% and less than 1 wt %). In various implementations, the sum of wt % of the sulfide electrolyte, the cathode active material, the conductive additives, and the PTFE binder equals 100 wt %.
The PTFE-based sulfide electrolyte layer 418 builds up favorable ion transfer between cathode and anode electrodes. In some examples, the PTFE-based sulfide electrolyte layer 418 has a thickness in a range from approximately 2 μm to approximately 30 μm (e.g., approximately 20 μm) after the calendaring. In some examples, the PTFE-based sulfide electrolyte layer 418 includes or consists of sulfide electrolyte and PTFE binder. In an example, the sulfide electrolyte may include 90 wt % to 99.9 wt % and the PTFE binders may include 0.1 wt % to 10 wt % (e.g., 2 wt %). In various implementations, the sum of wt % of the sulfide electrolyte and the PTFE binder equals 100 wt %.
In some examples, the dry process anode electrode layer 414 has a thickness after the calendaring in a range from approximately 50 μm to approximately 150 μm (e.g., approximately 100 μm). The dry process anode electrode layer 414 may include a sulfide electrolyte, an anode active material, conductive additives, and PTFE binder. In some examples, the sulfide electrolyte includes or consists of 0 wt % to 30 wt %, the anode active material comprises 50 wt % to 90 wt %, the conductive additives 0 wt % to 10 wt %, and the PTFE binder comprises greater than 0 wt % and less than or equal to 10 wt % (e.g., less than 1 wt %). In various implementations, the sum of wt % of the sulfide electrolyte, the anode active material, the conductive additives, and the PTFE binder equals 100 wt %.
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The substrate 516 protects and supports the thin sulfide membrane and may have a thickness in a range from approximately 20 μm to approximately 100 μm (e.g., approximately 50 μm), although the present application is also applicable to other thicknesses. In some examples, the substrate comprises polyethylene terephthalate (PET) film.
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In some examples, the electrically conductive adhesive layer includes polymer and conductive filler. In some examples, the conductive filler includes a carbon material Super P, carbon black, graphene, carbon nanotubes, carbon nanofibers. In some examples, the conductive filler includes metal powder such as Ag, Ni, or Al. In some examples, the polymer is configured to resist solvent and provide good adhesion. In some examples, the polymer includes epoxy, polyimide (polyamic acid), polyester, vinyl ester, thermoplastic polymers (less solvent resistant) include PVDF, polyamide, silicone, and acrylic. In some examples, a mass ratio of filler/polymer is in a range from approximately 0.1% to approximately 50%, (e.g., SP/PAA=1/3; SWCNT/PVDF=0.2%). In some examples, a thickness of the conductive adhesive is in a range from approximately 0.5 μm to approximately 20 μm.
In some examples, the solid electrolyte is selected from a group including or consisting of pseudobinary sulfide, pseudoternary sulfide, pseudoquaternary sulfide, halide-based solid electrolyte, and hydride-based solid electrolyte. Examples of pseudobinary sulfide include Li2S—P2S5 system (Li3PS4, Li7P3S11 and Li9.6P3S12), Li2S—SnS2 system (Li4SnS4), Li2S—SiS2 system, Li2S—GeS2 system, Li2S—B2S3 system, Li2S—Ga2S3 system, Li2S—P2S3 system, Li2S—Al2S3 system. Examples of pseudoternary sulfide include Li2O—Li2S—P2S5 system, Li2S—P2S5—P2O5 system, Li2S—P2S5—GeS2 system (Li3.25Ge0.25P0.75S4 and Li10GeP2S12), Li2S—P2S5—LiX (X═F, Cl, Br, I) system (Li6PS5Br, Li6PS5Cl, L7P2S8I and Li4PS4I), Li2S—As2S5—SnS2 system (Li3.833Sn0.833As0.166S4), Li2S—P2S5—Al2S3 system, Li2S—LiX—SiS2 (X═F, Cl, Br, I) system, 0.4LiI·0.6Li4SnS4 and Li11Si2PS12.
Examples of pseudoquaternary sulfide include Li2O—Li2S—P2S5—P2O5 system, Li9.54Si1.74P1.44S11.7Cl0.3, Li7P2.9Mn0.1S10.7I0.3 and Li10.35[Sn0.27Si1.08]P1.65S12. Examples of halide-based solid electrolyte include LisYCl6, LisInCl6, LisYBr6, LiI, Li2CdCl4, Li2MgCl4, Li2CdI4, Li2ZnI4, LisOCl. Examples of hydride-based solid electrolyte include LiBH4, LiBH4—LiX (X═Cl, Br, or I), LiNH2, Li2NH, LiBH4-LINH2, Li3AlH6. In other examples, other solid electrolyte that possesses low grain-boundary resistance.
In some examples, the cathode active material is selected from a group including or consisting of rock salt layered oxide, spinel, polyanion cathode materials, lithium transition-metal oxides, and lithiated metal oxide/sulfide. Examples of rock salt layered oxides include LiCoO2, LiNixMnyCo1-x-yO2, LiNixMnyAl1-x-yO2, LiNixMn1-xO2, Li1+x MO2. Examples of spinel include LiMn2O4 and LiNi0.5Mn1.5O4. Examples of polyanion cathode materials include LiV2(PO4)3. Surface-coated and/or doped cathode materials mentioned above can also be used such as LiNbO3-coated LiMn2O4, Li2ZrO3 or Li3PO4-coated LiNixMnyCo1-x-yO2, and Al-doped LiMn2O4. Examples of lithiated metal oxide/sulfide include LiTiS2), lithium sulfide, and sulfur.
In some examples, the anode active material is selected from a group including or consisting of carbonaceous material (e.g., graphite, hard carbon, soft carbon etc.), silicon, silicon mixed with graphite, Li4Ti5O12, transition-metals (e.g., Sn), metal oxide/sulfide (e.g., TiO2, FeS, etc.), other lithium-accepting anode materials, Li metal and Li alloy.
In some examples, the conductive additive is selected from a group including or consisting of carbon black, graphite, graphene, graphene oxide, Super P, acetylene black, carbon nanofibers, carbon nanotubes and other electronically conductive additives.
In some examples, the PTFE binder has a particle size in a range from approximately 300 um to approximately 800 um. In other examples, other fibrillating polymer binders are used (e.g., fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE), or a combination thereof).
In other examples, a binder polymer with film forming properties and high film elongation is used. In some examples, the binder polymer is selected from a group including or consisting of polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-co-hexafluoropropylene), polyvinylidene fluoride-trichlorethylene (polyvinylidene fluoride-cotrichlorethylene), polymethylmethacrylate, Polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyano Noethyl sucrose (cyanoethylsucrose), pullulan (pullulan), carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide or mixtures thereof.
The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure. Approximately as used herein may mean +/−10% of stated values.
Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information but information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202310179184.1 | Feb 2023 | CN | national |
