Power cell

Abstract

A battery cell has an anode, a cathode, a separator, and a first inorganic solid-state electrolyte having a melting point between 25 °C and 300 °C. The first inorganic solid-state electrolyte (ISSE) m

Description

Field of the invention The present disclosure relates to power cell technology, and more specifically to solidstate power cell technology. Background Currently, lithium-ion batteries face significant limitations such as low energy and power density, safety risks due to flammable liquid electrolytes, poor performance in cold temperatures and low affordability. Hence, there is a pressing need for improved batteries, especially improved solid-state batteries, to alleviate the problems associated with known lithium-ion batteries that concomitantly hinder the widespread adoption of electric vehicles (EVs). It cannot be overemphasized that currently available lithium-ion cells have reached their performance limit due to the use of flammable liquid electrolytes. Moreover, lithium-ion batteries require expensive electronic protection circuitry (such as a battery management system, BMS) and cooling systems during pack assembly for electric vehicles, in order to mitigate the power runaway problem associated with flammable liquid electrolytes; this contributes significantly to the four-fold decrease in energy density at the pack level. Finding an electrolyte that overcomes these problems is therefore a significant area of interest in battery research. One alternative is "solid-state cells", in which the flammable liquid electrolyte is replaced with a solid-state electrolyte. Various inorganic solid-state electrolytes (ISSEs) that exhibit excellent room-temperature ionic conductivity have emerged over the past decade. However, there are major hurdles in realizing all-solid-state batteries (SSBs) suitable for practical widespread usage. Challenges remain with existing fabrication protocols, and there are numerous issues with scaling existing technology beyond proof-of-concept examples that have been demonstrated in a lab. As a result, SSBs employing ISSEs have not yet been commercialised. Extensive literature exists detailing the attempts that are being made to fabricate SSBs that can operate at room temperatures. Some existing solutions employ compression cells or solution-based processing routes. However, major challenges exist with scaling these processes, and the cells produced tend to fail quickly due to the degradation of the interfaces between the various components of the cell. In particular, during the operation of known SSBs at room temperature, the typical expansion and contraction of the cathode or anode active materials tend to iead to interfacial gaps and cell failure concomitantly. Currently, significant pressures (3-700 MPa) are required during operation to prevent the formation of interfacial challenges (voids), but even with such high pressures being applied, the interfaces still rapidly degrade leading to failure as the cells operate at room temperature. Some attempts to address this issue that are currently under investigation involve adding liquid electrolyte (though flammable) or gel polymers to the cell designs, in an attempt to improve room-temperature performance over time. Cells produced in this manner may be referred to as "quasi-solid-state battery cells". However, present examples of such systems do not perform well due to the low transference number of the quasi-solid-state electrolyte. There are solid-state batteries that are known operate at elevated temperatures in excess of 350° C. Such temperatures are required to provide practical ionic conductivity within the sodium 3"-alumina ceramic membranes typically used in sodium-sulphur or zebra-type batteries. Apart from the low energy density of such batteries, the high operating temperature had raised safety issues and requires higher-cost materials for the cell housing and complex power management systems, limiting the use of this technology to large stationary installations or military applications. Summary of invention Despite recent advances in materials science, and the development of modern inorganic solid-state electrolytes like LISCON, Thio-LISICON, garnet, NASICON, halide, perovskites, antiperovskites, etc., with extremely high room-temperature ionic conductivities (some even more conductive than flammable liquid organic electrolytes), fabricating solid-state batteries which are capable of operating at room temperature is a major hurdle that has remained difficult to overcome for over a decade. This, therefore, underscores the importance of exploring multiple innovative, scalable and cost-effective ways to use the highly-conducting ISSEs to fabricate solid-state lithium- or sodium-ion batteries that can at least match the performance characteristics of state-of-the-art lithium- or sodium-ion batteries. Inorganic solid-state electrolytes provide opportunities for extreme fast charging as they have a much higher transference number (tf =1) in comparison to liquid (tf =0.4) or polymeric (tf =0.7) electrolytes. The properties of these ISSEs can then be further exploited for advanced cell chemistries employing metallic anodes. In order address to the above-described problems, herein is proposed a solid-state cell with an ISSE that is able to melt at a slightly elevated temperature (less than 300°C). The molten ISSE would then be able to flow into, and thereby fill, any interfacial voids or gaps between the cell components. Upon cooling to below the meiting point, the ISSE solidifies, preserving the structural integrity and ensuring long-term cycle stability of the battery. The melting of the ISSE can occur during normal operation of the cell, or may be conducted periodically in order to repair damage that occurs during operation of the battery with the ISSE in a fully solid state. In particular, the technology according to the present disclosure is expected to offer significant benefits when used in EVs. Exemplary ISSE materials include ternary halides (e.g. NaAICk, LhYCk), anti perovskites (e.g. LiaOCI, NaaOCI), and sulphides (e.g. argyrodite or thio-LISICON or their respective derivatives) that are able to melt at a slightly elevated temperature (T<300 °C). In some examples, the ISSE may be a blend of a meltable ISSE and other highly conducting ISSE having higher melting points. According to the present disclosure, the polymeric separator of a typical lithium-ion or sodium-ion (metal-ion) battery cell is replaced with a highly porous membrane consisting of a high-melting-point (above 300"C) material. The separator is impregnated with the meltable ISSE using any suitable process, which may include melt infusion or solutiontype infiltration. The membrane may be woven or non-woven and may comprise any of the following: • An inorganic oxide (SiO?, AhCh, ZrOz, CeO2, etc). ® A polymer (PAN, PTFE, etc). « A lithium- or sodium-conducting oxide (garnet, perovskite or nasicon type materials). The anode and cathode materials may comprise any suitable material, but must have good power stability. In some examples, the cathode may be a lithium- or sodium-based insertion cathode, such as: LiNixMnyCOzCh - LiMlxM2yPO4Fz - NaNixFeyMnzCh - NaMlxM2yPO4Fz - Na3V2(PO4)2F3 or their derivatives (where Ml and M2 are transition metals, and x, y, z are fractions or integers). The anode may be any suitable material, for example: « An insertion anode (graphite, hard carbon, Li4Ti50i2., Na4Ti50i2, Na2Ti3O? or their derivatives). « A conversion anode (metal oxides, MxOy, where M is a metal and x and y are integers). « A blend of insertion and conversion anodes. The separator can also be formulated as a free-standing film (FSF) comprising a polymer (PAN, PTFE, etc) and the meltable ISSE. Such solid-state batteries can be operated at room temperature with intermittent heating after certain periods of operation to melt the ISSE to fill any interfacial voids upon cooling. Applying temperature to EV batteries can be easily achieved in a controllable manner. The low melting point ISSE functions efficiently as an ion conductor, whilst also eliminating most of the interfacial challenges that are associated with known SSBs at room temperature. There are many further advantages of the cells according to the present disclosure, inciuding: easy processing and manufacturing conditions, compatible with state-of-the-art reel-to-reel equipment for manufacturing pouch, cylindrical or prismatic cells, reduced cost of the battery management system, replacement of the heavy liquid cooling system in the battery pack with inexpensive air cooling, and unprecedented gravimetric / volumetric energy density at the pack level. In a first aspect of the present disclosure, there is provided a cell comprising: an anode; a cathode; a separator; and a first inorganic solid-state electrolyte having a melting point between 25 °C and 300 °C. In some examples, the cell may be referred to as a solid-molten state cell. The "melting point" is understood be to be the melting point at atmospheric pressure. Any suitable measurement method known in the art may be used to determine the melting point. In some examples, the separator is porous. In some examples, the separator is highly porous. In some examples, the separator has a porosity of at least 5% by volume. In some examples, the separator has a porosity of at least 10% by volume. In some examples, the separator has a porosity of from 40% to 60 % by volume. In some examples, the separator has a porosity of from 40% to 50 % by volume. In some examples, the separator has a porosity of 40%, 45%, 50%, 55%, or 60% by volume. Any suitable measurement method known in the art may be used to determine the porosity of the separator. In some examples, the separator is a highly porous membrane consisting of a high-melting-point (above 300°c) material. The term ’membrane' used throughout is in reference to a separator as described herein. In some examples, a portion of the first inorganic solid-state electrolyte is at least partially contained within the separator. This means that at least some of the first ISSE is present within at least some of the pores of the separator. For example, the ISSE may be impregnated in the separator. The separator may be impregnated with the first ISSE using any suitable process, which may include melt infusion or solution-type infiltration. In some exampies, the separator is disposed substantially between the anode and the cathode, with the anode being disposed on a first side of the separator and the cathode being disposed on a second side of the separator. In some examples, the separator may be sandwiched between the anode and the cathode. In some examples, a portion of the first inorganic solid-state electrolyte extends through the separator, from the first side of the separator to the second side of the separator. In some examples, substantially all of the pores (of the separator) of a suitable size contain a portion of the first inorganic solid-state electrolyte. In some examples, the separator thickness is 50 pm or less. In some examples, the separator thickness is 40 pm or less. Any suitable measurement method known in the art may be used to determine the thickness of the separator. If the cell is a sodium-ion ceil, the separator is able to conduct sodium ions. If the cell is a lithium-ion cell, the separator is able to conduct lithium ions. For example, when the separator is a lithium-conducting oxide, the cell is a lithium-ion cell; and when the separator is a sodium-conducting oxide, the cell is a sodium-ion cell. In some examples, the separator comprises one or more components selected from: an inorganic oxide, a polymer, a lithium-conducting oxide, and a sodium-conducting oxide. In some examples, the inorganic oxide is one or more of: S1O2, AI2O3, ZrO?, CeO?, or a metal oxide. In some examples, the polymer is a high-melting point polymer, such as one or more of: polyacrylonitrile (PAN), and polytetrafluoroethylene (PTFE). In some examples, the lithium-containing oxide is one or more of: garnet, perovskite, or a NASICON type material. In some examples, the sodium-conducting oxide is one or more of: garnet, perovskite, or a NASICON type material. NASICON type material is a sodium (Na) super ionic, conductor, which refers to a family of solids with the chemical formula Nai+xZrzSixPa-xOiz, 0 <x <3, or its derivatives. In some examples, the separator is a polymer, and the polymer and the first inorganic solid-state electrolyte are a free-standing film composite. In some examples, the first inorganic solid-state electrolyte comprises one or more of: a ternary metal halide, a metal antiperovskite, and a metal sulphide. In some examples, the metal is lithium or sodium. When the cell is a lithium-ion cell, the first inorganic solid-state electrolyte may comprise one or more of: a ternary lithium halide, a lithium anti perovskite, and a lithium sulphide. When the cell is a sodium-ion cell, the first inorganic solid-state electrolyte may comprise one or more of: a ternary sodium halide, a sodium antiperovskite, and a sodium sulphide. In some examples, the first inorganic solid-state electrolyte comprises one or more of: Li3OCI, NasOCI, or AMX4, wherein 'X' is a halogen; 'A’ is an alkali metal; 'M' is a trivaient cation. In some examples, X is chloride, bromide or iodide. In some examples, X is chloride. In some examples, 'A' is Li or Na. If the cell is a lithium-ion cell, 'A' may be Li. If the cell is a sodium ion cell, 'A' may be Na. In some exampies, 'M' is Al, Ga, In, Sc, Y, or a lanthanide. In some examples, 'M' is Al or Y. In some examples, AMXa may be NaAICk or LiAICk. In some examples, the cell may further comprise a second inorganic solid-state electrolyte with a melting point greater than 300°C. The second inorganic solid-state electrolyte has a melting point great than the first inorganic solid-state electrolyte. In some examples, the second inorganic solid-state electrolyte is a sulphide. In some examples, the first inorganic solid-state electrolyte and the second inorganic solid-state electrolyte are blended together. The first and second inorganic solid-state electrolyte may be blended together by any suitable means known in the art. In some examples, the first inorganic solid-state electrolyte has a melting point of 25 °C to 295 °C, such as from 100 °C to 290 °C, in particular from 140 °C to 285 °C. In some examples, the first inorganic solid-state electrolyte has a melting point of at least 25, 30, 40, 50, 60, 70 , 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 225, or 250 °C. In some examples, the first inorganic solid-state electrolyte has a melting point Of up to 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 265, 270, 275, 280, 285, 290, 295, or 300 °C. In some examples, the cathode comprises lithium ions or sodium ions. This means that the cathode active material comprises lithium ions (e.g. in a lithium-ion cell) or sodium ions (e.g. in a sodium ion cell). In some examples, the cathode comprises one or more of: LiNixMnyCOzOz, UMlxM2yPO4Fz, NaNixFeyMnzOz, NaMlxM2yPO4Fz, NasVzCPChhFs, or any derivatives thereof; wherein Ml and M2 are transition metals, and x, y, z are fractions or integers, each of which may be selected from a range of 0 to 10. The cathode may further comprise one or more binders and / or conductive additives. In some examples, the anode is an insertion anode, a conversion anode, or a biend of insertion and conversion anodes. In some examples, the anode comprises one or more of: graphite, hard carbon, LUTisOiz, Na^isOiz, NazTiaO?, metal oxide, and metal chloride. In some examples, the insertion anode comprises graphite, hard carbon, LkTisOiz, Na^isOsz, Na / ThO? or their derivatives. In some examples, the conversion anode comprises metal oxides and / or metal chlorides. The anode may further comprise one or more binders and / or conductive additives. Also disclosed herein, in a second aspect of the disclosure, is a battery comprising two or more of the cells described herein. In some examples, the battery comprises 2, 3, 4, 5, 6, 7, 8, 9, 10 or more cells. Also disclosed herein, in a third aspect of the disclosure, is a method of use of any of the batteries disclosed herein, or any of the cells disclosed, in an electrically powered device or system. In some examples, the electrically powered device or system may be an electric vehicle. In some examples, the "electric vehicle" may be a car, bus, construction vehicle, agricultural vehicle, lorry, van, truck, boat, motorcycle, moped, plane (including eVTOL), or train. In some examples, the electrically powered device or system may be electric machinery or transportation machinery. Also disclosed herein, in a fourth aspect of the disclosure, is an electric vehicle comprising one or more cells as disclosed herein, and / or one or more batteries as disclosed herein. Further non-limiting examples and embodiments according to the present disclosure are described herein. Disclosed herein is a way to fabricate rechargeable solid-state Li- or Na- ion cells and batteries incorporating such cells as well as methods of using such cells and batteries. The solid-state cells according to the present disclosure provide high power, long lifespan, and good energy density at the park level compared to state-of-the-art Li- or Na- ion cells employing liquid flammable electrolytes. In one aspect, the present technology provides a power cell including an anode comprising a negative electrode active material, a cathode comprising a positive electrode active material comprising sodium ions or lithium ions, a membrane separating the anode and the cathode, and an electrolyte composition in contact with the anode, the cathode and the membrane, the electrolyte having a melting point of from 25 to 300 °C. Where the positive electrode active material comprises sodium ions, the membrane is sodium ion conducting and the ISSE is selected from the group consisting of ternary sodium halide, sodium anti perovskite and sodium sulphide, or a blend thereof. Where the positive electrode active material comprises lithium ions the membrane is lithium ion conducting and the ISSE is selected from the group consisting of ternary lithium halide, lithium antiperovskite and lithium sulphide. The flammable liquid electrolyte of state-of-the-art Li-ion cells is replaced in the battery cells according to the present disclosure with an inorganic electrolyte which is solid at room temperature. Since the electrolyte according to the present disclosure (for instance, halide or anti-perovskite) are easy to process in a typical dry-room environment, the cells can be easily manufactured using the same scalable, state-of-the-art reel-to-reel equipment for manufacturing cylindrical or prismatic cells. However, where the electrolyte according to the present disclosure is a sulphide solid-state electrolyte, manufacturing and processing should take place in the expected dry-room requirement. The cells according to the present disclosure can operate at room temperature as ternary halides and antiperovskites are very conducting at room temperature. However, where the cell is heated to above the melting point of the electrolyte, which is less than 300 °C, the electrolyte melts and functions effectively as an ion conductor. In addition, whilst in molten form, the electrolyte flows into any voids in the interfaces between the electrolyte and the surfaces of the anode and cathode particles, eliminating such interfacial voids and defects. This in turn reduces the risk of cell failure and / or reduced cell functionality / life cycle due to interfacial voids and defects. According to one embodiment, the membrane has an associated porosity of at least 40 vol.%, generally at least 50 vol.%, typically 40 to 60 vol.%. the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 50 pm. According to one embodiment, the power ceil comprises the membrane impregnated with the electrolyte sandwiched between the anode and the cathode. In another aspect, the present technology provides a battery that includes one or more of the cells described herein. According to an aspect according to the present disclosure, there is provided a method of operating the power cell or battery disclosed herein. The methods include providing the solid-state cell at a temperature at which the electrolyte composition is molten, wherein the temperature is less than 300 °C, and allowing movement of lithium ions or sodium ions through the membrane to charge or discharge the power battery. The methods may also include cooling the electrolyte composition to a temperature less than its melting point. According to a further aspect of the present disclosure, there is provided a method of improving the efficacy of the cell or battery described herein comprising: heating the power cell to a temperature at which the electrolyte composition is molten, wherein the temperature is less than 350 °C to allow the molten electrolyte composition to fill any voids in interfaces between the anode and the electrolyte, and between the cathode and the electrolyte. Generally the method of operating the cell or battery is 50 to 300 °C, suitably 100 to 200 °C, typically 125 to 175 °C, more preferably around 165 °C, Brief description of the drawings Examples of the present disclosure will now be described in detail with reference to the accompanying drawings, in which: FIG, 1A is a schematic drawing of an illustrative cell according to the present disclosure, provided at a temperature below the melting temperature of the first inorganic solid-state electrolyte (ISSE); and FIG. IB is a schematic of the power ceH of Fig. 1A at a temperature equal to or above the melting temperature of the first ISSE. Detailed description The following terms are used throughout as defined below. As used herein and in the appended claims, singular articles such as "a", "an" and "the" and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and ail examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential. As used herein, "about" will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, "about" will mean up to plus or minus 10% of the particular term, "Membrane" refers to any suitable separator that prevents the negative electrode active material from contacting the positive electrode active material, but which allows sodium or lithium ions to be selectively transported from the negative electrode, through the membrane, to the positive electrode, and vice versa. The membrane is not necessarily a dense sintered ceramic material like it Is usually the case for the aforementioned power battery types. As used herein an insertion electrode is used to refer to a host materia! with a crystailographic lattice that allows cations (Li+, Na+, etc.) to be inserted in the crystal structure with or without phase transformation concomitantly. As used herein, “conversion material" is used to refer to a material of the formula MX, where M is a transition metal, and X is oxygen or fluorine and reacts through the conversion reaction mechanism. As used herein a ternary halide is used to refer to AM1X4, or A3MIX6 where 'X' is an anion (Cl, Br, I); 'A' is an alkali metal (Li, Na, etc.); ’Ml' is a trivalent cation (Al, Ga, In, Sc, Y, lanthanides etc.); or A?M2X4 where M2 is a divalent metal (Ti, Zr, Hf, V, Cr, Mn, Fe, Zn, Mg), or A2M3X6 where M3 is a tetravalent metal or their derivatives like AsM'izM'zXe or A3-zM'i zM'zXs where M' and M" are any of the above metals, and 'z' is an integer. The term "hard carbon" is used to refer to a solid form of carbon that cannot be converted into graphite, even at high temperatures. As used herein, the term "ceramic" refers to a material that is made by ceramic processing, by mixing powders and other regents, forming into shapes and sintering at a very-high temperature to become completely dense. According to an aspect according to the present disclosure, there is provided a method of operating the cell or battery disclosed herein. The methods include providing the cell at a temperature at which the one or more of the solid-state electrolyte (ISSE) components is molten either intermittently or constantly, wherein the temperature is less than 300 °C, and is more than 5 °C higher than the melting point of the ISSE that is able to melt; and allowing movement of lithium ions or sodium ions through the membrane to charge or discharge the power battery. The method may also include cooling the electrolyte composition to a temperature less than its melting point. The solid-state cell may include: an anode comprising a negative electrode active material, generally including carbon, lithium ions or sodium ions, a cathode comprising a positive electrode active material comprising sodium ions or lithium ions, a membrane separating the anode and the cathode, the membrane having a porosity of at ieast 40 vo!.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm , a soiid-state electroiyte blend in contact with the anode, the cathode and the membrane, one of the solid-state electrolytes having a meiting point of from 25 to 300 °C (generally of from 140 to 300 °C), wherein, where the positive electrode active material comprises sodium ions, the membrane is sodium ion conducting and the solid-state electrolyte (ISSE) composition or blend is selected from the group consisting of ternary sodium halide, sodium anti perovskite and sodium sulphide, and where the positive electrode active material comprises lithium ions the membrane is lithium ion conducting and the solid-state electrolyte (ISSE) composition or blend is selected from the group consisting of ternary lithium halide, lithium anti perovskite and lithium sulphide. The solid-state electrolyte designed to melt has a melting point of from 25 to 300 °C, generally from 100 to 290 °C. The meiting point of the electrolyte is typically below the temperature of operation of the cell or battery disclosed herein, in particular the melting point of the electrolyte is generally below the temperature of charging or discharging the cell or battery disclosed herein. During charge and / or discharge of the present solid-state cells and batteries, the ISSE may be In the solid form, and get to the molten state after some time. The electrolyte may have a melting point of from above room temperature to about 300 °C, typically about 100 °C to about 285 °C, generally from about 130 to about 290 °C, suitably from about 140 to about 200 °C, According to one embodiment, the electrolyte has a melting point of 100 to 300 °C, generally 100 to 295 °C, preferably 150 to 290 °C. The temperature of operating the cell or battery (in particular, charging and discharging the cell or battery) may be about 25 °C to about 300 °C, for example where the temperature is above the melting point of one of the solid-state electrolytes in the cell, including, e.g., a temperature in a range between and including any two values selected from 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C. Generally, the temperature of operation of the ceil or battery is about 25 °C to about 290 °C, irrespective of the ceil chemistry. The temperature of operating the cell or battery is generally at least 5 °C higher than the melting point of one of the solid-state electrolytes, typically at least 10 °C, 15 °C, 20 °C, or 25 °C higher than the melting point of the solid-state electrolyte designed to melt. This ensures that at least one of the solid-state electrolytes is molten, and at a relatively high viscosity. The molten solid-state electrolyte can thus flow into any interfacial voids or defects. The cell is generally conditioned at a temperature at which one of the solid-state electrolyte composition is molten for at least 15 minutes, suitably at least 20 minutes, typically at least 30 minutes. The temperature at which one of the electrolyte composition is molten is generally maintained for at least 1 hour, suitably at least once a day. This timing is sufficient to allow the solid-state cell to charge and discharge. The cell may include a heat generator to allow heating to the required temperatures. The methods may also include cooling the electrolyte composition to a temperature less than its melting point, generally at least 10 °C lower than the melting point of the electrolyte, typically at least 20 °C lower than the melting point of the electrolyte, suitably to around room temperature. The ternary halide electrolyte may comprise lithium or sodium ions, and halide ions. Suitably the ternary halide is a chloride, although in some embodiments, fluorides may find utility. The ternary halide may comprise aluminium, or yttrium. According to one embodiment, the solid-state electrolyte (or the blend) is sodium-based. According to one embodiment, the solid-state electrolyte (or the blend) is lithium-based. The solid-state electrolyte composition may include sodium antiperovskite or lithium antiperovskite. The antiperovskite generally has the structure: MsAX where M - Na or Li, A - O' S and X - Cl, Br, or I. Suitably A = O. Generally, X = Cl, Br; typically X - Cl. According to one embodiment, one of the solid-state electrolyte is selected from: LiaOCI and NasOCI. One of the solid-state electrolytes may be a sodium sulphide or a lithium sulphide. Suitable sulphides include argyrodite compounds, comprising sodium or lithium, phosphorous, sulphur and a halogen. According to one embodiment, the sulphide solid-state electrolyte may have the structure MePSsX, where M = Na or Li, and X = Cl, Br, or I. Generally, X = Cl, Br; typically, X = Cl. One of the solid-state electrolytes may comprise sodium or lithium, germanium and sulphur; suitable electrolytes include Li4GeS4 and Na4GeS4. Another possibility is sodium or lithium, germanium, phosphorus and sulphur as in LiwGePaSi?. and NaioGePzSiz. The membrane has a first face towards the anode and a second face towards the cathode. The thickness of the membrane extends from the first face to the second face. Although the dimensions of the membrane are dependent on the dimensions of the cell, the thickness of the membrane is generally about 20 pm. The thickness of the membrane is typically at least 12 pm, and is suitably no more than 40 pm. The membrane typically has a porosity of at least 40 vol.%, generally at least 50%. Suitably, pores extend into the membrane from the first side and from the second side. Generally, the pores extend through the depth of the membrane providing space for the ISSE or ISSE blend to fill and allow the smooth migration of cations. Generally, at least 50% of the pores have a diameter of at least 1 pm. The membrane may include pores in more than one plane. According to one embodiment, the solid-state electrolyte (or the blend) is provided within the pores of the membrane. Generally, the electrolyte is provided within at least some pores of the membrane prior to the electrolyte being exposed to temperatures above its melting point (immediately after fabrication). Typically, the electrolyte is provided within the pores extending into the membrane from the first side and from the second side. According to one embodiment, the membrane is impregnated with the electrolyte, suitably through melt infusion or solution-type infiltration. Suitably the membrane (woven or non-woven) comprises or consists essentially of an inorganic oxide (SiOz, AI2O.3, ZrO?., etc.) or a lithium- or sodium-conducting oxide (garnet, perovskite or nasicon type materials) with a melting point above 300 °C, the melting point being at least 20 °C higher than the melting point of the electrolyte. Alternatively, the membrane may comprise or consist essentially of a polymer having a melting point above 300 °C, the melting point being at least 20 °C higher than the melting point of the electrolyte, or a combination of the polymer and the inorganic oxide, or the polymer and the lithium- or sodium-conducting oxide. According to one embodiment, the membrane may comprise or consist essentially of a free-standing composite film comprising the high-melting-point polymer and the ISSE that can melt. Typically, the melting point of the material used to form the membrane is at least 300 °C, the melting point being at least 20 °C higher than the melting point of the solid-state electrolyte that melts, typically at least 50 °C higher than the melting point of the solid-state electrolyte that melts. The membrane is generally not a dense sintered ceramic material. The negative electrode active material may be an insertion material, such as "hard carbon", graphite, a Li-based insertion material (like Li^TsOu) or a Na-based insertion material (like Na^isOn, NazTbOz, etc.). The negative electrode active material may be a conversion materials such as a transition metal oxides (FesCX FezOa, CO3O4, NiO, SIOx etc) or transition metal chlorides (FeCIs, NiCIz, etc).. The negative electrode active material may be a blend of insertion and conversion materials, in particular the insertion and conversion materials detailed above. The negative electrode active material is generally selected from the group consisting of carbon, or a compound comprising lithium ions or a compound comprising sodium Ions. In any embodiments, the positive electrode active material comprises sodium Ions or lithium ions. The positive electrode active material may include, consist essentially of or consist of lithium metal oxide or sodium metal oxide. The positive electrode active material may include one or more of transition metal (for instance, nickel, manganese, cobalt, iron, titanium), aluminium, oxygen, halogen, phosphate. The positive electrode active material may be a compound including lithium, nickel, manganese, cobalt and oxygen. The positive electrode active material may be a compound including lithium, iron and phosphate. The positive electrode active material may be a compound including sodium, nickel, iron, manganese and oxygen. The positive electrode active material may be a compound including sodium, iron and phosphate. The positive electrode active material may be a compound including sodium, vanadium, phosphate and fluorine. According to one embodiment, the positive electrode active material is selected from UNLMnyCozOz, xLi2Mn0.3.l-xLiQCh, LiQlxQ2yP04F?, NaNixFeyMnzOz, NaQlxQ2yPO4Fz, Na3V2(PO4)?.F3, where Q is a transition metal, and x, y, z are fractions or integers from 0 to 10, or their derivatives. The negative electrode active material may include carbon, lithium ions or sodium ions. Where the positive eiectrode active material includes lithium ions, the negative electrode active material may include lithium ions and / or carbon. Where the positive eiectrode active material includes sodium ions, the negative electrode active material may include sodium ions and / or carbon. The negative electrode active material may be in the form of a coating having a thickness of at least 45 pm. The positive electrode active material may be in the form of a coating having a thickness of at least 65 pm. According to one embodiment, one or both of the anode and the cathode are insertion electrodes. The anode and cathode may include a binder (organic; PTFE or inorganic: Mg(OH)z), and is usually formulated with the ISSE or ISSE blend as well as a conductive carbon additive. According to one embodiment, there is provided a method of operating a solid-state cell including: an anode comprising a negative electrode active material, selected from carbon (such as graphite, and hard carbon) and / or a conversion anode and / or a material containing lithium ions, a cathode comprising a positive electrode active material comprising lithium ions, a lithium ion conductive membrane separating the anode and the cathode, having a porosity of at least 40 vol.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm, a soiid-state electrolyte composition or blend in contact with the anode, the cathode and the membrane, one of the solid-state electrolyte having a melting point of from 25 to 300 °C, generally from about 100 to about 290 °C, wherein the solid-state electrolyte composition or the blend is selected from the group consisting of ternary lithium halide, lithium antiperovskite and lithium sulphide; the method comprising providing the ceil at a temperature at which one soiid-state electrolyte composition is molten, wherein the temperature is less than 300 °C, and is more than 10 °C higher than the melting point of the solid-state electrolyte that melts and allowing movement of lithium ions through the membrane. According to one embodiment, there is provided a method of operating a solid-state cell including: an anode comprising a negative electrode active material, selected from carbon (such as graphite, and hard carbon) and / or a conversion anode and / or a material including sodium ions, a cathode comprising a positive electrode active material comprising sodium ions, a sodium ion conductive membrane separating the anode and the cathode, having a porosity of at least 40 vo!.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm, a solid-state electrolyte composition or biend in contact with the anode, the cathode and the membrane, the soiid-state electrolyte having a melting point of from 50 to 300 °C, generally from about 100 to about 290 °C, wherein the solid-state electrolyte composition or the blend is selected from the group consisting of ternary sodium halide, sodium antiperovskite and sodium sulphide; the method comprising providing the solid-state ceil at a temperature at which one solid-state electrolyte composition is molten, wherein the temperature is less than 300 °C, and is more than 10 °C higher than the melting point of the solid-state electrolyte that melts and allowing movement of sodium ions through the membrane. According to one embodiment, there is provided a method of improving the efficacy of a power cell as described herein. The power cell may include: an anode comprising a negative electrode active material, generally including carbon, iithium ions or sodium ions, a cathode comprising a positive electrode active material comprising lithium ions or sodium ions, a membrane separating the anode and the cathode, the membrane having a porosity of at ieast 40 vol.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm, an electrolyte composition in contact with the anode, the cathode and the membrane, the electrolyte having a melting point of from 25 to 300 °C; wherein where the positive electrode active material comprises sodium ions the membrane is sodium ion conductive and the electrolyte composition is selected from the group consisting of ternary sodium halide, sodium anti perovskite and sodium sulphide, and where the positive electrode active material comprises lithium ions the membrane is lithium ion conductive and the electrolyte composition is selected from the group consisting of ternary lithium halide, lithium anti perovskite and lithium sulphide; the method comprising providing the cell at a temperature at which the electrolyte composition is molten, wherein the temperature is less than 320 °C, and is more than 10 °C higher than the melting point of the electrolyte and allowing the molten electrolyte to fill any voids in the interface between the electrolyte and the anode, and any voids in the interface between the electrolyte and the cathode. In any embodiments, the cell may further include a current collector, for instance including metal (Cu, Al, etc.) foils, nickel foam, nickel mesh, carbon foam, or carbon felt. In any embodiments, the solid-state cell may be of a size to hold the respective electrode active materials sufficient for about 1, about 2, about 5, about 10, about 20, or about 50 hours of discharge operation of the cell, or a range between and including any two of the foregoing values. In another aspect, the present technology provides a battery including one or more (e.gr, two or more) cells as described herein. For example, in any embodiments, the battery may include 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 150, 200, 250, 300, 350, 400, 450, or 500 cells as described herein, or a range between and including any two or more of the forgoing values, e,g., 1-500, 2-200 or 50-350 galvanic cells. More than one battery, each including more than one cell, may be used together to produce battery storage systems. For example, a 350 kW battery may include 320 individual cells, and a battery system designed to provide 2 MW of output may inciude 50 such batteries with 12,800 individual ceils. Hence, in any embodiments, the present technology provides battery systems that include 2 or more batteries, each of which includes 2 or more cells. Examples of the present disclosure will now be described by way of example only with reference to the accompanying figures, in which FIG. 1A is a schematic drawing of an illustrative cell according to the present disclosure, provided at a temperature below the melting temperature of the first ISSE. Figure IB schematically shows the same cell at a temperature above the melting point of the first ISSE. As illustrated in figure IB, the molten first ISSE has flowed into the voids between the electrolyte in solid form and the anode, cathode and membrane. This results in the elimination of most of the interfacial challenges typically observed when solid-state cells operate at room temperature. While certain embodiments have been illustrated and described, a person with ordinary skill in the art, after reading the foregoing specification, can effect changes, substitutions of equivalents and other types of alterations to the cells, batteries and methods of the present technology or derivatives thereof as set forth herein. Each aspect and embodiment described above can also have included or incorporated therewith such variations or aspects as disclosed in regard to any or all of the other aspects and embodiments. The present technology is also not to be limited in terms of the particular aspects described herein, which are intended as single illustrations of individual aspects of the present technology. Many modifications and variations of this present technology can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods within the scope of the present technology, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fail within the scope of the appended claims. It is to be understood that this present technology is not limited to particular methods, compounds, or systems, which can, of course, vary. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. Thus, it is intended that the specification be considered as exemplary only with the breadth, scope and spirit of the present technology indicated only by the appended claims, definitions therein and any equivalents thereof. No language in the specification should be construed as indicating any non-claimed element as essential. The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms "comprising," “including," "containing," etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase "consisting essentially of" will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase "consisting of" excludes any element not specified. Moreover, use of any of the foregoing terms in the description with respect to a particular element or embodiment also contemplates the use of any of the other terms. For example, use of "comprise" with respect to one element or embodiment will also be understood to disclose use of "consisting essentially of" or "consists of" in respect of the same element or embodiment and vice versa. In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the technology. This includes the generic description of the technology with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein. As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," "greater than," "less than," and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member, and each separate value is incorporated into the specification as if it were individually recited herein. All publications, patent applications, issued patents, and other documents (for example, journals, articles and / or textbooks) referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure. Other embodiments are set forth in the following claims, along with the full scope of equivalents to which such claims are entitled. The following paragraphs outline numbered exampies that are non-limiting examples of aspects of the present disclosure. Example 1: A method of operating a solid-state cell including: an anode comprising a negative electrode active material, generally including carbon, conversion material, lithium ions or sodium ions, a cathode comprising a positive electrode active material comprising sodium ions or lithium ions, a membrane separating the anode and the cathode, the membrane having a porosity of at least 40 vol.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm, a solid-state electrolyte composition or blend in contact with the anode, the cathode and the membrane, the electrolyte having a melting point of from 25 °C to 300 °C, wherein, where the positive electrode active material comprises sodium ions, the membrane is sodium ion conducting and the solid-state electrolyte composition or blend is selected from the group consisting of ternary sodium halide, sodium antiperovskite and sodium sulphide, and where the positive electrode active material comprises lithium ions, the membrane is lithium ion conducting and the solid-state electrolyte composition or blend is selected from the group consisting of ternary lithium halide, lithium anti perovskite and lithium sulphide; the method including providing the solid-state cell at a temperature at which one of the solid-state electrolyte composition is molten, wherein the temperature is less than 300 °C, and is more than 10 °C higher than the melting point of the solid-state electrolyte capable of melting; and allowing movement of lithium ions or sodium ions through the membrane to charge or discharge the solid-state battery / cell. Example 2: A method of improving the efficacy of a solid-state cell including: an anode comprising a negative electrode active material, generally including carbon, conversion material, lithium ions or sodium ions, a cathode comprising a positive electrode active material comprising sodium ions or lithium ions, a membrane separating the anode and the cathode, the membrane having a porosity of at least 40 vol.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm, a solid-state electrolyte composition or blend in contact with the anode, the cathode and the membrane, the soiid-state electrolyte having a melting point of from 25 °C to 300 °C, wherein, where the positive electrode active material comprises sodium ions, the membrane is sodium ion conducting and the solid-state electrolyte composition or blend is selected from the group consisting of ternary sodium halide, sodium antiperovskite and sodium sulphide, and where the positive electrode active material comprises lithium ions, the membrane is lithium ion conducting and the solid-state electrolyte composition or blend is selected from the group consisting of ternary lithium halide, lithium anti perovskite and lithium sulphide; the method comprising providing the cell at a temperature at which the electrolyte composition is molten, wherein the temperature is less than 300 °C, and is more than 10 °C higher than the melting point of the solid-state electrolyte and allowing the molten solid-state electrolyte to fill any voids in the interface between the solid-state electrolyte and the anode, and any voids in the interface between the solid-state electrolyte and the cathode. Example 3: A solid-state cell including: an anode comprising a negative electrode active material, generally including carbon, conversion material, lithium ions or sodium ions, a cathode comprising a positive electrode active material comprising sodium ions or lithium ions, a membrane separating the anode and the cathode, the membrane having a porosity of at ieast 40 vol.%, the membrane having a first face towards the anode, a second face towards the cathode and a thickness extending between the first face and the second face where the thickness is less than 40 pm a solid-state electrolyte composition or blend in contact with the anode, the cathode and the membrane, the solid-state electrolyte having a melting point of from 25 to 300 °C, wherein, where the positive electrode active material comprises sodium ions the membrane is sodium ion conducting and the solid-state electrolyte composition or blend is selected from the group consisting of ternary sodium haiide, sodium antiperovskite and sodium sulphide, and where the positive electrode active material comprises lithium ions the membrane is lithium ion conducting and the electrolyte composition is selected from the group consisting of ternary lithium halide, lithium antiperovskite and lithium sulphide. Example 4. The solid-state cell of Example 3, wherein the electrolyte composition has a melting point of 100 to 290 °C, generally 100 to 300 °C, preferably 140 to 295 °C, Example 5. The solid-state cell of either one of Examples 3 or 4 wherein the electrolyte composition is selected from NaAICk, LhYCk, LisOCI, NasOCI, LiePSsCI, LUGeSa, Na^GeS^ NaioGePzSuand derivatives thereof. Example 6. The solid-state cell of any one of Examples 3 to 5 wherein the negative electrode active material is selected from hard carbon, graphite, a material comprising lithium ions, a material comprising sodium ions and a metal oxide or metal chloride. Example 7. The solid-state cell of any one of Examples 3 to 6 wherein the negative electrode active material is selected from U4T5O12, Na^isOw, and Na2.Ti.3O7. Example 8. The solid-state cell of any of Examples 3 to 7 wherein the positive electrode 5 active material comprises or consists essentially of one or more of UNUMnyCo;-O?, xLi2MnO3.l-xL.iMO2, LiMlxM2yPO4Fz, NaNizFeyMmO?., NaMlxM2yPO4Fz, Na3V2(PO4)2F.3, where M is a transition metal, and x, y, z are fractions or integers from 0 to 10, or derivatives thereof. 10 Examples 9. The solid-state cell of any one of Examples 3 to 8 wherein the membrane is impregnated with the solid-state electrolyte material by melt infusion or solution-type infiltration. Example 10. A solid-state battery comprising two or more of the cells of any one of 15 Examples 3 to 9.

Claims

1. A cell comprising:an anode;a cathode;a separator; anda first inorganic solid-state electrolyte having a melting point between 25 °C and 300 °C.

2. The cell according to claim 1, wherein the separator is porous.

3. The cell according to claim 2, wherein the separator has a porosity of at least 10%by volume.

4. The cell according to claim 3, wherein the separator has a porosity of from 40% to 60 % by volume.

5. The cell according to any of claims 2-4, wherein a portion of the first inorganic solid-state electrolyte is at least partially contained within the separator.

6. The cell according to any of claims 2-5, wherein the separator is disposed substantially between the anode and the cathode, with the anode being disposed on a first side of the separator and the cathode being disposed on a second side of the separator.

7. The cell according to claim 6, wherein a portion of the first inorganic solid-state electrolyte extends through the separator, from the first side of the separator to the second side of the separator.

8. The cell according to any of claims 2-7, wherein substantially all of the pores of a suitable size contain a portion of the first inorganic solid-state electrolyte.

9. The cell according to any of claims 1-8, wherein the separator thickness is 50 pm or less.

10. The cell according to any of claims 1-9, wherein the separator comprises one or more components selected from: an inorganic oxide, a polymer, a lithium-conducting oxide, and a sodium-conducting oxide.

11. The cell according to claim 10 wherein, if present:(i) the inorganic oxide is one or more of: SiO?, AI2O3, ZrO?., CeOz, a meta! oxide;(ii) the polymer is one or more of: polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE);(iii) the iithium-containing oxide is one or more of: garnet, perovskite, or a NASICON type material; and / or(iv) the sodium-conducting oxide is one or more of: garnet, perovskite, or a NASICON type material.12, The cell according to any preceding claim, wherein the separator is a polymer, and the polymer and the first inorganic solid-state electrolyte are a free-standing film composite,13, The cell according to any preceding claim, wherein the first inorganic solid-state electrolyte comprises one or more of: a ternary metal halide, a metal antiperovskite, and a metal sulphide.14, The cell according to claim 13, wherein the metal is lithium or sodium.

15. The cell according to claims 13 or 14, wherein the first inorganic solid-stateelectrolyte comprises one or more of: U3OCI, NasOCI, or AMX4 wherein:’X' is an anion;'A' is an alkali metal; and’M' is a tnvalent cation.

16. The cell according to any preceding claim, further comprising a second inorganic solid-state electrolyte with a melting point greater than 300 °C.

17. The cell according to claim 16, wherein the first inorganic solid-state electrolyte and the second inorganic solid-state electrolyte are blended together.

18. The cel! according to any preceding claim, wherein the first inorganic solid-state electrolyte has a melting point of 25 °C to 295 °C, such as from 100°C to 290 °C, in particular from 140 °C to 285 °C.

19. The cell according to any preceding claim, wherein the cathode comprises lithium ions or sodium ions.

20. The cell according to claim 19, wherein the cathode comprises one or more of: LiNixMnyCOzOz, LiMlxM2yPO4Fz, NaNixFeyMnzOz, NaMlxM2yPO4Fz, NasVzCPO^zFs, or any derivatives thereof; wherein:Ml and M2 are transition metals; andx, y, z are fractions or integers, each selected from a range of 0 to 10,21, The cell according to any preceding claim, wherein the anode is an insertion anode, a conversion anode, or a blend of insertion and conversion anodes.

22. The cell according to claim 21, wherein the anode comprises one or more of: graphite, hard carbon, l^TisOiz, Na^isOn, NazTisO?, metal oxide, and metal chloride.23, A battery comprising two or more of the cells according to any of the preceding claims.

24. A method of use of the battery of claim 23, or the cells of any of claims 1-22, in an electrically powered device wherein, optionally, the electrically powered device is an electric vehicle.

25. An electrically powered device or system, comprising one or more cells according to any of claims 1 to 22, and / or one or more batteries according to claim 23.

Images