WO2023249834A1

WO2023249834A1 - Hybrid batteries with ionic conductive electrodes

Info

Publication number: WO2023249834A1
Application number: PCT/US2023/025110
Authority: WO
Inventors: Bing Tan; Yuhao Liao
Original assignee: Pacific Industrial Development Corporation
Priority date: 2022-06-20
Filing date: 2023-06-13
Publication date: 2023-12-28

Abstract

A hybrid cell is provided that has a positive electrode, a negative electrode, a porous separator and an electrolyte, wherein the positive electrode includes an ionic conductive cathode preloaded with a metal compound and, optionally, the negative electrode may also include an ionic conductive anode. The ionic conductive cathode and, when present, the ionic conductive anode, may further include an electrochemical active material and a polymer matrix for ion transport. The electrolyte is non-aqueous having a flash point > 93.4°C. The ionic conductive cathode and, when present, the ionic conductive anode has a thickness that is in the range of 10 micrometers (pm) to 100,000 pm and a porosity that is < 40%. An energy storage device incorporating one or more of these hybrid cells is also provided.

Description

Hybrid Batteries with Ionic Conductive Electrodes

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the filing date under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63/353,650 filed June 20, 2022, the entire contents of which is hereby incorporated herein by reference.

FIELD

[0002] This invention generally relates to an electrochemical cell and an energy storage device that contains one or more of such cells, such as primary or secondary battery cells used in rechargeable batteries, battery packs, etc. More specifically, the present disclosure provides a hybrid electrochemical cell design that comprises at least one solid state ionic conductive electrode and a liquid electrolyte.

BACKGROUND

[0003] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0004] A conventional lithium-ion battery generally comprises one or more cells, which includes a negative electrode, a non-aqueous electrolyte, a separator, and a positive electrode, along with a current collector for each of the electrodes. All of these components are sealed in an enclosure or housing. The separators are usually polyolefin films with hundreds of nanometer pores that prevent physical contact between the positive and negative electrodes, while allowing for the transport of lithium ions back and forth between the electrodes. The non-aqueous electrolyte is typically a solution that contains a lithium salt placed between each electrode and the separator. An example of a typical electrolyte used in a battery cell capable of providing high ionic conductivity at a relatively low viscosity comprises a concentration of about 0.8 molar to 1.5 molar LiPFe in one or more organic carbonate solvents. [0005] One issue with conventional battery cells is that they may cause a fire during a thermal runaway situation, mainly resulting from the interaction between the non-aqueous electrolyte and the charged electrodes. Conventional non-aqueous electrolytes are flammable and may burn under abusive conditions mainly because the organic carbonate solvents used therein contain linear carbonate compounds, such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and/or diethyl carbonate (DEC). These linear carbonate compounds are present because of their low viscosity, which enhances both ionic conductivity and the ability of the non-aqueous electrolyte to “wet” the separator and the electrodes. However, they have low flash points (i.e. , < 33°C) and are flammable in air.

[0006] In order to address this safety concern, the industry has begun to move towards the use of highly concentrated electrolytes, which may reduce the flammability of the electrolytes by limiting the free movement of linear carbonates. In other words, the flammable linear carbonate molecules are bonded to the dissolved lithium compound or salt and are difficult to vaporize when heated, which means that the flash point of the electrolyte will be significantly increased to make it non-flammable or even incombustible. Based on the common definition of flammable and combustible liquids, the flammable liquids have a flash point < 60°C and the combustible liquids have a flash point between 60°C and 93.4°C. In order to be incombustible, the flash point for the liquid needs to be >93.4°C.

[0007] To improve safety, an alternative way is to eliminate the use of any flammable or combustible solvent in the electrolyte by incorporating only an incombustible solvent. Cyclic carbonates, in general, have a high flash point that is > 93.4°C and are not combustible in air. Propylene carbonate has a flash point of 132°C, while ethylene carbonate has a flash point of 143°C. They can be used as the solvent for a noncombustible electrolyte. Upon the addition of a lithium salt, the electrolyte will become even less combustible since the salt is not combustible and a portion of the organic solvent molecules will bond around the dissolved salt ions.

[0008] However, for both a concentrated salt electrolyte and an incombustible electrolyte without any linear carbonates, the viscosity exhibited by the electrolytes becomes significantly higher. The viscosity of a typical linear carbonate (i.e., diethyl carbonate) is 0.75 centipoise (cP), while the cyclic carbonate (i.e., propylene carbonate) has a value > 1.9 cP. In an electrolyte having the same solvent(s) (i.e., ethylene carbonate/ethyl methyl carbonate = 30/70), the viscosity of the electrolyte can increase from about 1 .0 cP with 0 mol/kg of LiPFe present to about 10 cP when 2 mol/kg of LiPFe is present. When the viscosity of the electrolyte increases, it becomes more difficult for the electrolyte molecules to move into the pores in the electrodes, which is an issue associated with poor “wetting”. When the pores of the electrode are not filled with the electrolyte, the electrode active materials will not be able to participate into the electrochemical reactions. In this situation, the electrode will not deliver the designed capacity and rate performance. This issue becomes further magnified for electrodes that comprise a higher mass loading or a thicker thickness in order to exhibit a high areal capacity.

[0009] This “wetting” issue may be associated not only with the high viscosity arising from electrolytes, but also with electrodes that exhibit a very large thickness. Such thicker electrodes are useful for achieving high energy density in batteries, such as in 3- dimensional (3D) batteries. Unlike conventional electrodes, which have a thickness in the range of about 10 micrometers (pm) to < 200 pm, these thick electrodes may have a thickness in the range of 200 pm to 10,000 pm or 1 centimeter (cm). Thus, it becomes more difficult and challenging even for an electrolyte with low viscosity to penetrate through all of the pores in a thick electrode due to the longer distance associated with the electrode’s thickness.

[0010] Another area that has seen strong industrial interest in recent years is the development of solid-state batteries. One type of a solid-state battery is represented by polymer batteries in which the separator is made from a polymer electrolyte and the electrodes are filled with the polymeric electrolyte. However, several difficulties encountered during the commercialization of these polymer-based batteries has limited their utilization. First, the polymer electrolyte-based separators available for use in such batteries, generally exhibit weak mechanical strength and low ionic conductivity at room temperature. Thus, in order to avoid an issue with the creation of an electrical short, e.g., short circuit, the separator used in a polymer-based battery has to be made relatively thick. Second, these polymer batteries generally need to be operated at a relatively high temperature in order to increase its ionic conductivity (e.g., 60°C or above).

[0011] Therefore, there is a need to find an alternative electrochemical cell design that is less challenging with respect to commercial viability. An electrochemical cell in which thick electrodes may be satisfactorily “wet” and can be operated at or near room temperature (e.g., ~25°C) is desirable.

SUMMARY

[0012] This disclosure generally provides a hybrid cell for use as an electrochemical cell. This hybrid cell includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and a porous separator. The positive electrode comprises an ionic conductive cathode layer preloaded with one or more metal compounds and a current collector that is in contact with the cathode, such that the metal compounds provide ions for ion transport within the hybrid cell. The negative electrode comprises at least a current collector. Optionally, the negative electrode may also comprise an ionic conductive anode layer preloaded with one or more metal compounds that provide ions for ion transport within the hybrid cell along with the current collector that is in contact with the anode. The non-aqueous electrolyte is positioned between and in contact with both the negative electrode and the positive electrode, such that the non-aqueous electrolyte supports the reversible flow of ions between the positive electrode and the negative electrode. The porous separator is placed between the positive electrode and negative electrode, such that the separator separates the anode and the cathode. The separator is filled with the non-aqueous electrolyte and is permeable to the reversible flow of ions there through.

[0013] According to one aspect of the present disclosure, the ionic conductive cathode and/or the ionic conductive anode, when present, has a thickness of 10 micrometers (pm) to 100,000 pm; alternatively, the thickness is 100 pm to 10,000 pm. In addition, the ionic conductive cathode and/or the ionic conductive anode, when present, may have a porosity <40%; alternatively, the porosity is <10%. [0014] The metal ions provided by the one or metal compounds in the ionic conductive cathode and/or the ionic conductive anode, when present, may be lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, or a combination thereof. The metal compound may comprise at least one lithium compound selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium bis(trifluoromethane- sulfonyl)imide (LiTFSi), lithium bis(fluorosulfonyl)imide (LiFSi), lithium tetrafluoroborate (LiBF4), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOPB), lithium perchlorate (LiCIC>4), LiCI, LiBr, Lil, Lih, LiNOs, and a mixture thereof.

[0015] According to another aspect of the present disclosure, the ionic conductive cathode and/or the ionic conductive anode, when present, may further comprise one or more electrochemical active materials and at least one polymer. The at least one polymer may be selected from the group consisting of polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), polyurethane, polyimide, polyamide, and a mixture thereof. In addition, the one or more electrochemical active materials may be selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, metal fluorides, sulfur, selenium, vanadium oxide, and a mixture thereof. Alternatively, the electrochemical active material is selected from the group consisting of graphite, hard carbon, soft card, carbon nanotubes (CNTs), graphene, tin, tin oxide, antinomy, antimony oxide, silicon, silicon monoxide, lithium titanate, titanium oxide, niobium oxide, tungsten oxide, lithium vanadate, and a mixture thereof.

[0016] According to yet another aspect of the present disclosure the non-aqueous electrolyte has a flash point > 93.4 °C; alternatively, the non-aqueous electrolyte has a flash point > 140 °C. The non-aqueous electrolyte may comprise one or more organic solvents that have a flash point > 93.4°C. The non-aqueous electrolyte may also comprise a metal salt in a concentration that is > 2 molar (M). This metal salt may be a lithium salt. [0017] According to another aspect of the present disclosure, the separator includes a porosity that is > 30% and/or a thickness that is in the range of 1 pm to 50 pm. Alternatively, the separator has a porosity that is > 40% and/or a thickness that is in the range of 5 pm to 15 pm.

[0018] According to another embodiment of the present disclosure, an energy storage device comprising at least one cell as described above or as further defined herein is provided.

[0019] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DESCRIPTION OF THE DRAWINGS

[0020] In order that this disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings. The components in each of the drawings may not necessarily be drawn to scale, but rather emphasis is placed upon illustrating the principles of the invention.

[0021] Figure 1 is a schematic representation of a hybrid cell according to the teachings of the present disclosure.

[0022] Figure 2 is a schematic representation of an ionic conductive electrode used in the hybrid cell according to the teachings of the present disclosure;

[0023] Figure 3 is a graphical plot comparing the charge and discharge voltage curves measured for a conventional cell and a hybrid cell formed according to the teachings of the present disclosure.

[0024] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. It should be understood that throughout the description and drawings, corresponding reference numerals indicate like or corresponding parts and features. DETAILED DESCRIPTION

[0025] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. The present disclosure generally provides an electrochemical cell design that is configured to avoid the wetting issue for electrodes, in particular for thick electrodes. In addition, this electrochemical cell is capable of operating at or near ambient temperature (e.g., ~25°C, alternatively, 25°C).

[0026] According to one aspect of the present disclosure, the electrochemical cell represents a hybrid cell design because it utilizes one or more solid state electrodes pre- loaded with at least one ionic conductive material and a non-aqueous electrolyte having a moderate to high viscosity. In this design, the ionic conductivity inside the electrodes is provided by the pre-loaded ionic conductive material and does not rely upon “wetting” capability from the non-aqueous electrolyte. Although the non-aqueous electrolyte may have much higher ionic conductivity than the pre-loaded ionic conductive material, the ionic conductivity inside the electrodes may be much lower if the non-aqueous electrolyte does not effectively fill the pores in the electrodes. When the viscosity of the non-aqueous electrolyte is too high, the electrolyte may not be able to enter into the nano-sized pores present in the electrodes. In this case, the pores will not be sufficiently “wet” by the electrolyte, e.g., the pores stay “dry”, thereby, reducing or eliminating conductivity within the pores. In this manner, the ionic conductivity inside the electrodes may be lower with a non-aqueous electrolyte present, rather than for electrodes in which the pores or spaces between the cathode or anode active material(s) are filled with a pre-loaded ionic conductive material even if the non-aqueous electrolyte has higher ionic conductivity.

[0027] The pre-loaded ionic conductive material does not need to substantially contribute to the mechanical strength of the electrode as is commonly the case for the use of a conventional polymer electrolyte. The composition of the ionic conductive material may be adjusted for high ionic conductivity, for example by increasing the lithium salt concentration. Besides enhanced ionic conductivity inside the electrode pores, an additional benefit with using pre-loaded electrodes is an improvement in safety. The electrodes are mainly filled with solid-state ionic conductive material(s), which has none or limited amount of organic solvent(s) diffused from the non-aqueous electrolyte in the separator. One of the major reasons for the occurrence of thermal runaway in a conventional liquid electrolyte lithium ion cell is that the organic solvents react with the charged graphite anode violently under abusive conditions and release flammable gas molecules that ignite and burn quickly. If these organic solvents are not present in the anode, there will be no flammable gas molecules produced even under abusive conditions. The cell safety will be greatly improved for the use of solid-state electrodes. [0028] According to another aspect of the present disclosure, for the separator layer, a porous thin film is used to act as the matrix to hold a liquid non-flammable electrolyte with moderate to high viscosity. One skilled in the art will understand that a gel-like electrolyte may also be used in principle without exceeding the scope of the present disclosure. The use of the porous film is desirable because the thickness may be controlled to low values, for example in the range of 5 micrometers (pm) to 20 pm. The pores in the separator are typically larger than the pores in the electrodes, which could be tens to hundreds of nanometers and could be tuned to larger size when needed. Alternatively, the pores in the separator range from about 10 nanometers (nm) to about 500 nanometers; alternatively, from about 20 nm to 300 nm; alternatively, greater than 15 nm and less than 400 nm. The separator film (i.e., 5-15 pm) is much thinner than the electrodes (e.g. > 50 pm). Both the larger pore sizes and thinner thickness of the porous film will make the separator much easier to be “wet” than the pores in the electrode even if the same non-aqueous electrolyte with a high viscosity is used. Moreover, when desirable, the porous film may incorporate hydrophilic filler materials that will make it easier to “wet” the surface and pores with the non-flammable and highly viscous nonaqueous electrolyte. In comparison to a conventional polymer electrolyte (i.e.> 60 pm), the separator thickness is much thinner, which increases the cell energy density and enhances the lithium ion diffusion rate across the separator.

[0029] The hybrid electrochemical cell according to the teachings contained herein is described throughout the present disclosure using lithium ion or lithium metal cells in order to more clearly illustrate the electrochemical cell and applications associated therewith. One skilled in the art will understand that the electrochemical cell may utilize other ions without exceeding the scope of the present disclosure. In other words, the teachings of the present disclosure can be applied to cells that utilize other ions including, without limitation, sodium ions, potassium ions, magnesium ions, aluminum ions, hydroxide ions, and combinations thereof, along with the corresponding electrochemical active materials and polymers associated with or in support of the chosen ions.

[0030] For the purpose of this disclosure, the terms "about" and "substantially" as used herein with respect to measurable values and ranges refer to the expected variations known to those skilled in the art (e.g., limitations and variability in measurements).

[0031] For the purpose of this disclosure, the terms "at least one" and "one or more of” an element are used interchangeably and may have the same meaning. These terms, which refer to the inclusion of a single element or a plurality of the elements, may also be represented by the suffix "(s)" at the end of the element. For example, "at least one metal", "one or more metals", and "metal(s)" may be used interchangeably and are intended to have the same meaning.

[0032] Referring now to Figure 1 , the hybrid electrochemical cell 1 generally comprises a positive electrode 10, a negative electrode 17, a non-aqueous electrolyte 19, and a porous separator 5. The positive electrode comprises an ionic conductive cathode 3 preloaded with one or more metal compounds and a current collector 7 that is in contact with the cathode 3, wherein the metal compounds provide ions for ion transport within the hybrid cell 1. The negative electrode 17 comprises an anode 13 and a current collector 15 that is in contact with the anode 13; wherein, optionally, the anode 13 may also be an ionic conductive anode preloaded with one or more metal compounds that provide ions for ion transport within the hybrid cell 1. The non-aqueous electrolyte 19 is positioned between and in contact with both the negative electrode 17 and the positive electrode 10. This non-aqueous electrolyte 19 supports the reversible flow of ions between the positive electrode 10 and the negative electrode 17. The porous separator 5 is placed between the positive electrode 10 and negative electrode 17, such that the separator 5 separates the anode 13 and a portion of the electrolyte 20A from the cathode 3 and the remaining portion of the electrolyte 20B; wherein the separator 5 is permeable to the reversible flow of ions there through. [0033] Still referring to Figure 1 , the ionic conductive cathode 3 and when present, the ionic conductive anode 13, may be configured as solid-state electrode films. Alternatively, the hybrid electrochemical cell 1 comprises both an ionic conductive cathode 3 and an ionic conductive anode 13. The electrode films may have a thickness that ranges from a few micrometers (e.g., > 10 pm) to a few millimeters (e.g., < 10 mm). For high energy cells, the areal capacity loading in general is > 3 mAh/cm² with an electrode film thickness of > 55 pm for a graphite anode and > 51 pm for a LiNio.8Coo.1Mno.1O2 (NCM811) cathode. The areal capacity is expected to be much higher when thicker electrode(s) are utilized. For example, with a thickness of 550 pm, the graphite electrode may be able to provide an areal capacity as high as 30 mAh/cm². This increase in the areal capacity is significant for both cost reduction and energy density enhancement because thinner current collector(s) and/or porous separator may be used when a thicker electrode is present. For this reason, a high areal capacity loading and a thick ionic conductive electrode are preferred for use in the hybrid cell designed according to the present disclosure.

[0034] However, if an electrode is too thick such as a few centimeters (e.g., > 10 cm), then its performance may be too low to for any practical applications because of the long diffusion length over which the ions have to transported. Therefore, there is a limit for the maximum electrode thickness. This maximum value may be adjusted based on the performance requirement or need associated with the selected application. In general, the thickness of the electrode film is selected in the range of 10 pm to 100,000 pm (10 cm). Alternatively, the thickness of the electrode films may range from about 50 pm to about 50,000 pm; alternatively, the range is from about 100 pm to about 10,000 pm.

[0035] The purpose of the metal compound in the ionic conductive electrode(s) is to provide metal ion conductivity for the metal cells or metal ion cells. In other words, the one or more metal compounds present in the ionic conductive electrode(s) provide ions for ion transport within the hybrid cell. These metal ions, which arise from the one or metal compounds in the ionic conductive cathode and/or the ionic conductive anode, when present, may be lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, hydroxide ions, or a combination thereof. The type of metal ion may be selected based on the application or type of device in which the hybrid cell is incorporated. [0036] The metal compound(s) may generally comprise a metal phosphate, metal sulfonyl imide, metal borate, metal perchlorate, metal halide, or metal nitrate compound. The selection of the metal compound(s) is determined by the degree of electrochemical stability that the metal compound has when placed or used on an individual electrode side (e.g., at cathode or anode) of the hybrid cell. For example, when the metal is lithium, the one or more metal compounds may be selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), lithium bis(fluorosulfonyl)imide (LiFSi), lithium tetrafluoroborate (LiBF4), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOPB), lithium perchlorate (LiCIC ), lithium chloride (LiCI), LiBr, Lil, Lih, LiNOs, and a mixture thereof. Lithium nitrate (LiNOs) may be used for the cathode side of the hybrid cell, while lithium chloride (LiCI) may be used for the anode side. The lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) may be used for either or both the anode and cathode side of the hybrid cell.

[0037] According to another aspect of the present disclosure, the ionic conductive electrode(s), e.g., the ionic conductive cathode and, when present, the ionic conductive anode, may also comprise one or more electrochemical active materials and at least one polymer. The polymer(s) may be configured to act as the matrix for transport of the metal ions, as well as a binder to hold the electrode film in place against the current collector. Various types of polymers may be utilized provided that either do not dissolve in or at least exhibit a very low solubility in the chosen liquid electrolyte system. Several examples of these polymers may include, but not be limited to, polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), polyurethane, polyimide, polyamide, and a mixture thereof. Alternatively, when the electrolyte comprises an organic carbonate, the polymer(s) are preferably PTFE, PVDF, PVDF-HFP, and/or a mixture thereof.

[0038] The electrochemical active materials used in the electrode(s) provide for energy storage and may act as an ionic conductive component capable of providing for metal-ion conductivity in the metal (e.g., lithium, etc.) or metal-ion based cells. These electrochemical active material(s) may comprise materials that can perform oxidation or reduction reactions in the cell. Generally, the anode active material is a material that can take and release ions reversibly at the operating voltage window of the anode, which is typically between 10 mV and 3.0 V vs. Li/Li+ for lithium ion cells. The anode active material(s) may be selected from, but not limited to, graphite, hard carbon, soft card, carbon nanotubes (CNTs), graphene, tin, tin oxide, antinomy, antimony oxide, silicon, silicon monoxide, lithium titannate, titanium oxide, niobium oxide, tungsten oxide, lithium vanadate, and a mixture thereof.

[0039] The cathode active material(s) for lithium ion-based cells (e.g. lithium ion cells, lithium metal cells, anode-free cells) include, but are not limited to, lithiated metal oxides (e.g., lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide with various Ni/Co/Mn molar ratios), lithiated metal phosphates (e.g., lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate), metal fluorides, sulfur, selenium, vanadium oxide, and mixtures thereof. One skilled in the art will understand that similar cathode active materials comprising other metal(s), e.g., different than lithium, may be utilized without exceeding the scope of the present disclosure when the ionic conductive electrode(s) in the hybrid cell contains a metal compound that provides metal ions that are different than lithium as required or desired for use in a selected application.

[0040] Referring now to Figure 2, in an ionic conductive electrode 100 (i.e., the cathode 3 and optionally, the anode 13 along with the corresponding current collector 7, 15), the space between the particles of the electrochemical active material 105 may be filled with an ionic conductive material 110. This ionic conductive material 110 comprises a mixture of one or more metal compounds 115 and at least one polymer 120. Due the limitations associated with the processing and preparation of ionic conductive electrodes 100, there may be empty voids 125 or spaces that remain in the ionic conductive material 110. The porosity associated with the ionic conductive electrode 100, e.g., the amount of empty voids 125 present in the ionic conductive material 110, should be as small as possible because the presence of too many voids can block the ionic transport rate and reduce the ionic conductivity associated with the ionic conductive electrode 100. The electrode porosity of the ionic conductive electrode 100 is expected to be < 40%, alternatively, < 30%, alternatively, < 20%, or alternatively, < 10%.

[0041] The particle size of the electrochemical active material can be in the range of 1 nm to 100 pm, preferred to be 100 nm to 50 pm, and more preferred to be 500nm to 20 pm.

[0042] The conductivity of the ions in the solid state electrode is affected by the polymer to metal (e.g., lithium, etc.) compound molar ratio. With an increase of the metal compound concentration, the ionic conductivity of the metal compound/polymer binder mixture generally increases. In this case, a higher content of the metal compound is necessary in order to achieve higher ionic conductivity. However, it is possible that when too much of the metal compound is present in the ionic conductive material 110 a reduction in ionic conductivity may be observed due to the formation of metallic clusters. The formation of such metallic clusters has been observed for an ionic conductive material comprising LiTFSi/PEO. Therefore, there is an optimized ratio for each metal compound/polymer that can be used in the hybrid cell. When too much of the metal compound is present, the mechanical strength of the electrode film will also decrease because such mechanical strength is generally provided by the polymer. The metal compound/polymer mass ratio is in the range of 100/1 to 1/10, alternatively, in the range of 30/1 to 1/5, alternatively, in the range of 10/1 to 1/3, or alternatively, in the range of 5/1 to 1/1.

[0043] Solid-state batteries represent one application in which solid-state ionic conductive electrodes have been used. In particular, these batteries generally incorporate a polymer electrolyte. However, due to the low ionic conductivity and the poor mechanical stability of the polymer electrolyte when used as a separator layer, according to another aspect of the present disclosure, a porous separator filled with incombustible electrolyte is used in the hybrid cell of the present disclosure. This porous separator is an electrochemical inert layer with high porosity that is made from a polymer, such as, without limitation, polyethylene (PE), polypropylene (PP), cellulose, polyimide and mixtures thereof. The porous separator exhibits good flexibility and decent mechanical strength. Glass fibers may be included in the separator in order to improve its wettability for the electrolyte.

[0044] The porosity of the separator is expected to be relatively large defined as at least > 30% in order to accommodate the expected viscosity of the electrolyte. Alternatively, the porosity of the separator is in the range of 30% to about 80%, alternatively in the range of about 35% to about 70%, or alternatively in the range of about 40% to about 60%. When desirable, the separator may comprise a hydrophilic filler material, selected from, but not limited to, AI2O3, AIOOH, SiC>2, TiO2, or a mixture thereof. This filler material may be present in the separator at a mass percentage that is in the range of 0.1 % to 40%, alternatively, the range of about 1 % to about 10% relative to the entire mass of the separator. The separator may have a thickness that is in the range from 1 pm to about 50 pm, alternatively, from about 3 pm to about 30 pm, and even alternatively from about 5 pm to about 15 pm. The separator may have a ceramic coating with the thickness of 0.5 pm to about 6 pm on at least one side, alternatively, only on one side.

[0045] The electrolyte is a liquid-type or gel-type electrolyte that has high flash point, which is > 93.4°C. Alternatively, the flash point is > 100°C; alternatively, > 140°C.

[0046] The use of high viscosity is preferred for incombustible electrolytes that comprise a locally or overall concentrated metal (e.g., lithium, etc.) salt and a limited amount of organic solvents. Unlike the electrolyte for a conventional lithium ion battery, which has a salt concentration <1.5 M, the concentrated salt electrolyte according to the present disclosure has a salt concentration > 2.0 M and sometimes even to the saturated level. When LiTFSi or LiFSi is utilized, the salt concentration may go up to 4.0 M and/or higher. The solvents in the concentrated salt electrolyte could include, without limitation, linear carbonates, cyclic carbonates, and/or a mixture of linear carbonates and cyclic carbonates.

[0047] The electrolyte can have a relatively low lithium compound concentration in the range of 0.1 molar (M) to 2.0 M, alternatively, in the range of 0.5 M to 1 .5 M, dissolved in an incombustible organic solvent or a mixture of incombustible solvents. The incombustible organic solvent is an organic solvent with flash point > 93.4 °C. Those solvents can be selected from, but not limited to, ethylene carbonate (EC), propylene carbonate (PC), y-butyrolactone (yBL), sulfolane, and fluoroethylene carbonate. In this case, the prepared electrolyte is incombustible and will not catch fire. A flammable organic solvent, such as linear organic carbonates, is not used in the electrolyte.

[0048] The current collector 7 in the positive 10 electrode may be made of any metal known in the art for use in an electrode of a metal or metal-ion (e.g., lithium, etc.) battery, such as for example, without limitation, aluminum, titanium, stainless steel, nickel, copper, carbon, zinc, gallium, silver, and combinations or alloys formed therefrom. The current collector 15 used in the negative electrode 17 may be a metallic foil that does not react with the metal (e.g., lithium, etc.) ions. Several examples of such metallic foils may include, but not be limited to, Cu, Fe, Ti, Ni, Mo, W, Zr, Mn, carbon, and lithium metal alloys. Alternatively, the metallic foil for the current collector 15 of the negative electrode 17 comprises Cu, Fe, Ni, or a mixture or alloy thereof.

[0049] The specific examples provided in this disclosure are given to illustrate various embodiments of the invention and should not be construed to limit the scope of the disclosure. The embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0050] Examples

[0051] A single-layer pouch cell comprising conventional electrodes (Comparative Example A) and a single-layer pouch cell comprising ionic conductive electrodes according to the teachings of the present disclosure were fabricated and tested. In Comparative Example A, the cathode had a composition of 97 wt.% LiNiMnCoC (NCM622), 1.5 wt.% carbon nanotubes (CNTs), and 1.5 wt.% polyvinylidene fluoride (PVDF) with an areal mass loading of 24.2 mg/cm² and a thickness of 66 pm. The porosity was 18%. The anode in Comparative Example A had a composition of 95 wt.% graphite and 5 wt.% PVDF with an areal mass loading of 15.0 mg/cm² and a thickness of 85 pm. Its porosity was 21 %. In Example 1 comprising the ionic conductive electrodes, the cathode had a composition of 86.5 wt.% NCM622, 1.5 wt.% CNTs, 8 wt.% lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), and 4 wt.% PVDF with an areal mass loading of 27.1 mg/cm² and a thickness of 88 pm. The porosity was 16%. The anode in Example 1 had a composition of 76 wt.% graphite, 16 wt.% LiTFSi, and 8 wt.% PVDF with an areal mass loading of 18.7 mg/cm² and a thickness of 113 pm. Its porosity was 17%. Thus, in the ionic conductive electrodes of Example 1 , LiTFSi is the metal compound and the PVDF is the polymer matrix for ion diffusion, while NCM622 and graphite are the cathode and anode active materials, respectively.

[0052] The electrolyte used in both Comparative Example A and Example 1 was saturated LiTFSi with 0.1 m lithium difluoro(oxalato)borate (LiDFOB) in a 45/45/10 mixture of ethylene carbonate, polyethylene, and fluoroethylene carbonate (EC/PE/FEC). Thus, a highly viscose and incombustible electrolyte was used.

[0053] Comparative Example A was configured according to the traditional electrode design for high energy cells and Example 1 was configured as a hybrid cell using the ionic conductive electrode design of the present disclosure. The electrodes used in both Comparative Example A and Example 1 were calendared as thin as possible. Both electrodes in the hybrid cell (Example 1 ) comprising the pre-loaded LiTFSi showed slightly less porosity than the electrodes used with the conventional design (Comparative Example A).

[0054] For the electrode, the areal mass loading was the measured electrode film mass in mg/cm² without the current collector as measured using a digital analytic scale. The electrode film thickness was measured with a micrometer. From the film mass loading and its thickness, the film porosity was calculated by using the equation: porosity equals 1 - ((areal mass loading/electrode material true density)/measured film thickness. After the full cell was fabricated, it was cycled with an Arbin Battery Tester using a slow current density at ~C/10 charge/discharge rates.

[0055] The measured electrochemical data for the cells as shown in Figure 3 demonstrates that without the pre-loaded LiTFSi in the electrodes, the conventional cell (Comparative Example A) delivers about 55 mAh/g capacity from the cathode side, while the value became 92 mAh/g with the pre-loaded LiTFSi (Example 1 ). The ionic conductive electrodes were not optimized with relatively high porosity, which is expected to slightly reduce the hybrid cell’s overall performance. This comparison, however, does demonstrate the positive contribution achieved by the hybrid cell design having pre- loaded LiTFSi into the electrodes as compared to a conventional cell.

[0056] As used herein, the term “cell” or “battery cell” generally refers to the basic electrochemical unit of a battery that contains the electrodes, separator, and electrolyte. In comparison, a “battery” or “battery pack” refers to a collection of cell(s), e.g., one or more cells, and includes a housing, electrical connections, and possibly electronics for control and protection.

[0057] According to yet another aspect of the present disclosure, one or more of the hybrid cells comprising one or more ionic conductive electrodes pre-loaded with a metal compound prepared according to the teachings of the present disclosure may be combined to form a larger capacity battery or battery pack, such as a lithium-ion secondary battery used in an electric vehicle (EV). The one or more cells may be incorporated in series, in parallel, or in a combination thereof in order to form the battery or battery pack. One skilled in the art will also appreciate that in addition to using the hybrid cells in a lithium-ion secondary battery, the same principles may be used to encompass or encase one or more cells into a housing for use in another application.

[0058] The housing may be constructed of any material known for such use in the art and be of any desired geometry required or desired for a specific application. For example, lithium-ion batteries generally are housed in three different main form factors or geometries, namely, cylindrical, prismatic, or soft pouch. The housing for a cylindrical battery may be made of aluminum, steel, or the like. Prismatic batteries generally comprise a housing that is rectangular shaped rather than cylindrical. Soft pouch housings may be made in a variety of shapes and sizes. These soft housings may be comprised of an aluminum foil pouch coated with a plastic on the inside, outside, or both. The soft housing may also be a polymeric-type encasing. The polymer composition used for the housing may be any known polymeric materials that are conventionally used in lithium-ion secondary batteries. One specific example, among many, include the use of a laminate pouch that comprises a polyolefin layer on the inside and a polyamide layer on the outside. A soft housing needs to be designed such that the housing provides mechanical protection for the hybrid cells present in the battery.

[0059] Within this specification, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0060] Those skilled-in-the-art, in light of the present disclosure, will appreciate that many changes can be made in the specific embodiments which are disclosed herein and still obtain alike or similar result without departing from or exceeding the spirit or scope of the disclosure. One skilled in the art will further understand that any properties reported herein represent properties that are routinely measured and can be obtained by multiple different methods. The methods described herein represent one such method and other methods may be utilized without exceeding the scope of the present disclosure.

[0061] The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

CLAIMS What is claimed is:

1 . A hybrid cell for use as an electrochemical cell, the hybrid cell comprising: a positive electrode, the positive electrode comprising an ionic conductive cathode layer preloaded with one or more metal compounds and a current collector that is in contact with the cathode, wherein the metal compounds provide ions for ion transport within the hybrid cell; a negative electrode, the negative electrode comprising a current collector; wherein, optionally, the negative electrode comprises an ionic conductive anode layer preloaded with one or more metal compounds and a current collector that is in contact with the anode, wherein the metal compounds provide ions for ion transport within the hybrid cell; a non-aqueous electrolyte positioned between and in contact with both the negative electrode and the positive electrode; wherein the non-aqueous electrolyte supports the reversible flow of ions between the positive electrode and the negative electrode; and a porous separator placed between the positive electrode and negative electrode, such that the separator separates the anode and the cathode; wherein the separator is filled with the non-aqueous electrolyte and is permeable to the reversible flow of ions there through.

2. The hybrid cell according to Claim 1 , wherein the ionic conductive cathode and/or the ionic conductive anode, when present, has a thickness of 10 micrometers (pm) to 100,000 pm

3. The hybrid cell according to Claim 2, wherein the ionic conductive cathode and/or the ionic conductive anode, when present, has a thickness of 100 pm to 10,000 pm.

4. The hybrid cell according to Claims 1 or 2, wherein the ionic conductive cathode and/or the ionic conductive anode, when present, has a porosity <40%.

5. The hybrid cell according to Claim 4, wherein the ionic conductive cathode and/or the ionic conductive anode, when present, has a porosity <10%.

6. The hybrid cell according to any of Claims 1 to 5, wherein the metal ions provided by the one or metal compounds in the ionic conductive cathode and/or the ionic conductive anode, when present, are lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, or a combination thereof.

7. The hybrid cell according to any of Claims 1 to 6, wherein the metal compound comprises at least one lithium compound selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), lithium bis(fluorosulfonyl)imide (LiFSi), lithium tetrafluoroborate (LiBF4), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOPB), lithium perchlorate (LiCIC ), LiCI, LiBr, Lil, Lih, LiNOs, and a mixture thereof.

8. The hybrid cell according to any of Claims 1 to 7, wherein the ionic conductive cathode and/or the ionic conductive anode, when present, further comprises one or more electrochemical active materials and at least one polymer.

9. The hybrid cell according to Claim 8, wherein the at least one polymer is selected from the group consisting of polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), polyurethane, polyimide, polyamide, and a mixture thereof.

10. The hybrid cell according to Claim 8, wherein the one or more electrochemical active materials is selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, metal fluorides, sulfur, selenium, vanadium oxide, and a mixture thereof.

11. The hybrid cell according to Claim 8, wherein the electrochemical active material is selected from the group consisting of graphite, hard carbon, soft card, carbon nanotubes (CNTs), graphene, tin, tin oxide, antinomy, antimony oxide, silicon, silicon monoxide, lithium titanate, titanium oxide, niobium oxide, tungsten oxide, lithium vanadate, and a mixture thereof.

12. The hybrid cell according to any of Claims 1 to 11 , wherein the non-aqueous electrolyte has a flash point > 93.4 °C.

13. The hybrid cell according to any of Claims 1 to 12, wherein the non-aqueous electrolyte has a flash point > 140 °C.

14. The hybrid cell according to Claims 12 or 13, wherein the non-aqueous electrolyte comprises one or more organic solvents having a flash point > 93.4°C.

15. The hybrid cell according to Claims 12 or 13, wherein the non-aqueous electrolyte comprises a metal salt in a concentration that is > 2 molar (M).

16. The hybrid cell according to Claim 15, wherein the metal salt is a lithium salt.

17. The hybrid cell according to any of Claims 1 to 16, wherein the separator includes a porosity that is > 30% and/or a thickness that is in the range of 1 pm to 50 pm.

18. The hybrid cell according to any of Claims 1 to 17, wherein the separator includes a porosity that is > 40% and/or a thickness that is in the range of 5 pm to 15 pm.

19. An energy storage device comprising at least one cell according to Claim 1 .

20. The energy storage device according to Claim 19, wherein the metal ions provided by the one or metal compounds in the ionic conductive cathode and/or the ionic conductive anode, when present, are lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, or a combination thereof.

21 . The energy storage device according to any of Claims 19 or 20, wherein the metal compound comprises at least one lithium compound selected from the group consisting of lithium hexafluorophosphate (LiPFe), lithium bis(trifluoromethanesulfonyl)imide (LiTFSi), lithium bis(fluorosulfonyl)imide (LiFSi), lithium tetrafluoroborate (LiBF4), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOPB), lithium perchlorate (LiCIC ), LiCI, LiBr, Lil, Lih, LiNOs, and a mixture thereof.

22. The energy storage device according to any of Claims 19 to 21 , wherein the ionic conductive cathode and/or the ionic conductive anode, when present, has a thickness of 10 micrometers (pm) to 100,000 pm and/or a porosity < 40%.

23. The energy storage device according to any of Claims 19 to 22, wherein the ionic conductive cathode and/or the ionic conductive anode, when present, further comprises an electrochemical active material and a polymer; wherein the polymer is selected from the group consisting of polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEG), polyurethane, polyimide, polyamide, and a mixture thereof; wherein the electrochemical active material is selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium manganese nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, metal fluorides, sulfur, selenium, vanadium oxide, and a mixture thereof.

24. The energy storage device according to any of Claims 19 to 23, wherein the ionic conductive cathode and/or the ionic conductive anode, when present, further comprises an electrochemical active material and a polymer; wherein the polymer is selected from the group consisting of polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEG), polyurethane, polyimide, polyamide, and a mixture thereof; wherein the electrochemical active material is selected from the group consisting of graphite, hard carbon, soft card, carbon nanotubes (CNTs), graphene, tin, tin oxide, antinomy, antimony oxide, silicon, silicon monoxide, lithium titanate, titanium oxide, niobium oxide, tungsten oxide, lithium vanadate, and a mixture thereof.