Doped lithiated solid-state electrolyte materials

Abstract

Provided herein is a method of making a doped lithium lanthanum zirconium oxide. The method comprises contacting an aqueous solution comprising lithium ions with a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide; forming a precipitate comprising lithium; and calcining the precipitate comprising lithium to form the doped lithium lanthanum zirconium oxide. Also provided are related methods, products, starting materials and intermediates.

Description

Doped lithiated solid-state electrolyte materials BACKGROUND OF THE INVENTION

[0001] The present disclosure relates to doped lithiated solid-state electrolyte materials, in particular, but not exclusively, doped lithium lanthanum zirconium oxides.

[0002] The present invention concerns doped lithiated solid-state electrolyte materials. More particularly, but not exclusively, this invention concerns a method of making a doped lithiated solid-state electrolyte material. The invention also concerns a doped lithiated solid-state electrolyte material, a composition for forming a doped lithiated solid-state electrolyte material and a two-part reaction mixture composition for forming a doped lithiated solid-state electrolyte material.

[0003] Doped lithiated solid-state electrolyte materials are typically produced by solid- state synthesis. This typically requires extensive periods of heating at high temperature. Such methods are energy-intensive and may not be scalable to produce large amounts of material. Furthermore, in some cases, a significant amount of processing of the produced material has to be undertaken. For example, the lithiation process may involve ball milling, which is energy-intensive and not always reliable. The lithiation process may involve spray drying or freeze-drying, which may be energy-intensive because substantially all solvent has to be removed.

[0004] The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method of making a doped lithiated solid-state electrolyte material, in particular, but not exclusively a doped lithium lanthanum zirconium oxide (sometimes referred to herein as LLZO). SUMMARY OF THE INVENTION

[0005] According to a first aspect of the invention, there is provided a method of making a doped lithiated solid-state electrolyte material (preferably, a doped lithium lanthanum zirconium oxide), the method comprising: P037226WO1contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material, one or more species for incorporation into the solid- state electrolyte material comprising one or more dopants (preferably, contacting a solution comprising lithium ions - especially, an aqueous or at least partially aqueous solution comprising lithium ions - with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide); forming a precipitate comprising lithium; and heating (preferably, calcining) the precipitate comprising lithium to form the doped lithiated solid-state electrolyte material (preferably, a doped lithium lanthanum zirconium oxide).

[0006] For the avoidance of doubt, “lithiated solid-state electrolyte material” means a solid-state electrolyte material comprising lithium. Preferably, the lithiated solid-state electrolyte material is a doped lithium lanthanum zirconium oxide.

[0007] Thus, preferably, the method according to the first aspect of the invention is a method of making a doped lithium lanthanum zirconium oxide, the method comprising: contacting a (preferably aqueous, or at least partially aqueous) solution comprising lithium ions with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide; forming a precipitate comprising lithium; and heating (especially, calcining) the precipitate comprising lithium to form the doped lithium lanthanum zirconium oxide.

[0008] For the avoidance of doubt, contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material (especially, contacting a solution comprising lithium ions – preferably, an aqueous or at least partially aqueous solution comprising lithium ions - with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) may cause the formation of the precipitate comprising lithium. The formation of the precipitate comprising lithium need not be a separate step from contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material. P037226WO1

[0009] The applicant has unexpectedly found that it is possible to make doped lithiated solid-state electrolyte materials (especially doped lithium lanthanum zirconium oxides) using benign aqueous precipitation chemistry. Examples of such methods typically do not generate harmful waste products, and typically use precursors that are relatively stable. For example, contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material (especially, contacting a solution comprising lithium ions – preferably, an aqueous or at least partially aqueous solution comprising lithium ions - with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) may optionally take place at a temperature of no more than 60°C, optionally no more than 50°C, optionally no more than 40°C and optionally no more than 30°C. Contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material (especially, contacting a solution comprising lithium ions – preferably, an aqueous or at least partially aqueous solution comprising lithium ions - with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) may take place at a temperature of at least 0°C, optionally at least 5°C, optionally at least 10°C and optionally at least 15°C. Contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material (especially, contacting a solution comprising lithium ions – preferably, an aqueous or at least partially aqueous solution comprising lithium ions - with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) optionally takes place at a temperature of 5-60°C, optionally 10-40°C and optionally 15-25°C. Contacting a lithium species with a solid comprising one or more species for incorporation into the solid-state electrolyte material (especially, contacting a solution comprising lithium ions – preferably, an aqueous or at least partially aqueous solution comprising lithium ions - with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) optionally takes place at ambient temperature.

[0010] The lithium species may be in the form of lithium ions, especially in the form of a solution comprising lithium ions; preferably, an aqueous or at least partially aqueous P037226WO1solution comprising lithium ions. It will be understood that the liquid component of an aqueous solution is water (or is substantially water, optionally with other liquid components being present in minor amounts, for example as impurities). It will also be understood that the liquid of a partially aqueous solution comprises water and may comprise other polar or non-polar (especially, polar) liquids, such as one or more alcohols (such, for example, as ethanol) or other polar liquids (such as acetone). Preferably, the lithium ions are in aqueous solution.

[0011] The solid comprising one or more species for incorporation into the solid-state electrolyte material (which is preferably a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into a doped lithium lanthanum zirconium oxide) may comprise a precipitate comprising one or more species for incorporation into the solid- state electrolyte material (preferably lanthanum, zirconium and one or more dopant species for incorporation into a doped lithium lanthanum zirconium oxide).

[0012] The method of the first aspect of the present invention optionally takes place in an aqueous liquid.

[0013] The method optionally comprises contacting a solid comprising one or more species for incorporation into the solid-state electrolyte material (which is preferably a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into a doped lithium lanthanum zirconium oxide) with lithium ions. The lithium ions may be provided by forming a solution (preferably, an aqueous solution) comprising lithium ions (for example, by dissolving a lithium salt) and contacting said solid (optionally a precipitate) with said solution. Alternatively or additionally, the solid will be present in a liquid (such as water or a mixture comprising water), and the method may comprise dissolving a lithium salt in said liquid to provide lithium ions. The lithium salt may comprise any suitable lithium salt, such as lithium hydroxide, lithium nitrate, lithium halide or lithium acetate.

[0014] The method of the present invention is a method of making a doped lithiated solid- state electrolyte material (preferably, a doped lithium lanthanum zirconium oxide). Such a material may comprise a lattice, optionally a crystalline lattice, with certain species occupying the lattice sites and certain species occupying sites between the lattice sites (the sites between the lattice sites often being known as “interstitial sites”). One or more dopants P037226WO1may optically occupy sites between the lattice sites and / or may occupy lattice sites Optionally, one or more species for incorporation into the solid-state electrolyte material (which is preferably a doped lithium lanthanum zirconium oxide) may comprise species for forming the lattice structure, therefore optionally for occupying lattice sites. For example, if the doped lithiated sold-state electrolyte material comprises doped lithium lanthanum zirconium oxide, then the dopant may be any suitable element other than lithium, lanthanum, zirconium and oxygen. For example, the dopant may be any metal or semi-metal (such as boron or tantallum) other than lithium, lanthanum and zirconium. For example, the dopant may comprise a halogen. Optionally, some of the oxygen may be replaced by halogen.

[0015] The method may comprise forming the solid (optionally a precipitate) comprising one or more species for incorporation into the solid-state electrolyte material (preferably, forming the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide). Forming the solid comprising one or more species for incorporation into the solid-state electrolyte material may comprise mixing at least two compositions, at least one of which comprises one or more species (preferably including one or more dopant species) for incorporation into the solid-state electrolyte material. Optionally, at least one of the compositions is in the form of a solution (preferably an aqueous solution). Optionally, at least one of the compositions is in the form of a suspension (preferably an aqueous suspension). Optionally, two of the at least two compositions are in the form of a solution. (Thus, the preferred forming of a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into a doped lithium lanthanum zirconium oxide may comprise mixing at least two solutions, at least one of which comprises the one or more dopant species for incorporation into the solid-state electrolyte material.) Optionally, at least one of the compositions comprises a base, such as hydroxide, carbonate or hydrogen carbonate. Optionally, at least one of the compositions comprises one or more species for forming the lattice structure of the doped lithiated solid-state electrolyte material, and optionally comprises one or more dopants. Optionally, at least one of the compositions comprises one or more species for forming the lattice structure of the doped lithiated solid-state electrolyte material, but no dopant, and another composition comprises one or more dopant. Optionally, at least one of P037226WO1the compositions comprises one or more species for forming the lattice structure of the doped lithiated solid-state electrolyte material, and one or more dopant, and another composition comprises one or more dopant, and optionally base. Optionally, at least one of the compositions comprises one or more species for forming the lattice structure of the doped lithiated solid-state electrolyte material, and one or more dopant, and another composition comprises base, but no dopant. Optionally, one of the compositions may be acidic.

[0016] For example, a first composition, optionally in the form of a solution may comprise one or more of Zr, La and optionally one or more dopant. The first composition may optionally be acidic. A second composition, optionally in the form of a solution but also optionally in the form of a suspension, may comprise one or more of: a base, one or more dopant and one or more of Zr and La. Such a dopant may optionally be provided as a polyoxometalate. The provision of two such compositions which may be mixed to form a solid (optionally a precipitate) has proved to be an effective way of making a solid (in the form of a precipitate) from which doped lithium lanthanum zirconium oxide can be made.

[0017] Optionally, a first composition, optionally in the form of a solution may comprise one or more of Zr, La and optionally one or more dopant. The first composition may optionally be acidic. A second composition, optionally in the form of a solution but also optionally in the form of a suspension, may comprise one or more of: a base and one or more dopant, but not one or more of Zr and La. The provision of two such compositions which may be mixed to form a precipitate has proved to be an effective way of making a solid (optionally in the form of a precipitate) from which doped lithium lanthanum zirconium oxide can be made.

[0018] Optionally, a first composition, optionally in the form of a solution may comprise one or more of Zr, La and optionally one or more dopant. The first composition may optionally be acidic. A second composition, optionally in the form of a solution but also optionally in the form of a suspension, may comprise a base, but not one or more dopant, nor one or more of Zr and La. The provision of two such compositions which may be mixed to form a solid (optionally in the form of a precipitate) has proved to be an effective way of making a precipitate from which doped lithium lanthanum zirconium oxide can be made. P037226WO1

[0019] Forming the solid comprising one or more species for incorporation into the solid- state electrolyte material (preferably, forming the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) optionally takes place at pH of at least about 3.5, optionally at least about 4.0, optionally at least about 4.5 and optionally at least about 5.0. The forming may optionally takes place at pH of no more than about 8.0, optionally no more than about 7.5, optionally no more than about 7.0, optionally no more than about 6.5, optionally no more than about 6.0, optionally no more than about 5.5 and optionally no more than about 5.0.

[0020] The solid comprising one or more species for incorporation into the solid-state electrolyte material (preferably, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into a doped lithium lanthanum zirconium oxide) may comprise those species necessary for forming the doped lithiated solid-state electrolyte (preferably, the doped lithium lanthanum zirconium oxide) apart from lithium. For example, if the doped lithiated solid-state electrolyte is a doped LLZO, the solid comprising one or more species for incorporation into the solid-state electrolyte material may comprise lanthanum, zirconium and any dopants (but no lithium).

[0021] The precipitate comprising lithium may optionally comprise those species necessary for forming the doped lithiated solid-state electrolyte (preferably, the doped lithium lanthanum zirconium oxide). For example, if the doped lithiated solid-state electrolyte is a doped LLZO, the solid comprising one or more species for incorporation into the solid-state electrolyte material may comprise lithium, lanthanum, zirconium and any dopants.

[0022] Forming a precipitate comprising lithium may comprise providing a source of anions with which lithium may form an insoluble salt. For the avoidance of doubt, “providing” does not mean that the source of anions with which lithium may form an insoluble salt is added in a separate step. For example, a composition comprising zirconium, lanthanum and one or more dopant species for the formation of doped lithium lanthanum zirconium oxide may also comprise a source of anions with which lithium may form an insoluble salt.

[0023] For the avoidance of doubt, more than one dopant may be provided. P037226WO1

[0024] Preferably, the step of forming a precipitate comprising lithium is or comprises: subsequent to the contacting step, providing a source of anions with which lithium forms an insoluble salt, thereby forming the precipitate comprising lithium. Without wishing to be bound by theory, it is thought that providing the source of anions subsequent to the contacting step, rather than before, may be an effective way to minimize the amount of lithium ions remaining in solution, for example by reducing the total amount of liquid (especially water) present as a vehicle for components necessary to form product, in turn reducing the amount of liquid (especially water) available to solubilize lithium ions. This may lead to a greater yield of doped lithiated solid-state electrolyte material, especially a greater yield of a doped lithium lanthanum zirconium oxide. Preferably, the source of anions is or comprises a source of carbonate anions. Carbonate anions may provide an especially effective way to promote precipitation of lithium ions out of solution (especially, out of aqueous solution). The source of carbonate anions may be or comprise carbon dioxide. Using carbon dioxide rather than a carbonate salt (such, for example, as ammonium carbonate) may reduce or eliminate unwanted byproducts (such, for example, as ammonia); the lithium carbonate produced may be reused without special purification.

[0025] Forming a precipitate comprising lithium may optionally comprise (i) contacting the lithium species (optionally lithium ions) with a composition comprising the solid comprising one or more species for incorporation into the solid-state electrolyte material, and subsequently providing a source of anions with which lithium may form an insoluble salt; (ii) contacting a source of anions with which lithium may form an insoluble salt with the composition comprising a solid comprising one or more species for incorporation into the solid-state electrolyte material, and subsequently providing the lithium species (optionally lithium ions); or (iii) contemporaneously contacting (a) the lithium species (optionally lithium ions) and (b) a source of anions with which lithium may form an insoluble salt with (c) a composition comprising the solid comprising one or more species for incorporation into the solid-state electrolyte material or (d) contacting a composition comprising the solid comprising one or more species for incorporation into the solid-state electrolyte material with a source of anions with which lithium may form an insoluble salt and, and subsequently providing lithium ions. In certain circumstances, option (i) is preferred because this may lead to a greater yield of the desired product. Lithium ions may P037226WO1be provided by dissolving a soluble lithium salt in a liquid, such as the carrier liquid of said solid. Alternatively or additionally, lithium ions may be provided by providing a solution of lithium ions and contacting said solution with said solid. When the doped lithiated solid- state electrolyte material is or comprises a doped lithium lanthanum zirconium oxide, forming the precipitate comprising lithium may comprise (i) contacting the (preferably aqueous or at least partially aqueous) solution comprising lithium ions with the solid (optionally, a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, and subsequently providing a source of anions with which lithium may form an insoluble salt (especially a source of carbonate ions); (ii) contacting the solid (optionally, a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide with a source of anions with which lithium may form an insoluble salt (especially a source of carbonate ions), and subsequently providing the (preferably aqueous or at least partially aqueous) solution comprising lithium ions; or (iii) contemporaneously contacting the (preferably aqueous or at least partially aqueous) solution comprising lithium ions and a source of anions with which lithium may form an insoluble salt (especially a source of carbonate ions) with the solid (optionally, a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide. In certain circumstances, option (i) is preferred because this may lead to a greater yield of the doped lithium lanthanum zirconium oxide.

[0026] The reference to an insoluble salt refers to the salt optionally being insoluble in aqueous solution, being sufficiently insoluble to precipitate from solution.

[0027] As described herein, the source of anions with which lithium may form an insoluble salt may comprise a source of carbonate anions. Lithium carbonate is sparingly soluble in many liquids, such as aqueous liquids. The source of carbonate anions may comprise one or more of carbonate ions, hydrogencarbonate ions and carbon dioxide. Carbon dioxide may be particularly effective because the solution from which the precipitate comprising lithium is removed is a solution of lithium carbonate, which may be reused without further purification. This therefore reduces the loss of lithium. P037226WO1

[0028] Heating the precipitate comprising lithium to form the doped solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) may optionally comprise calcining the precipitate comprising lithium. In the present case, calcining comprises heating to provide a phase transition. Heating the precipitate comprising lithium to form the doped solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) may optionally comprise heating the precipitate comprising lithium to a temperature of at least 500 °C, optionally at least 600 °C, optionally at least 700 °C, optionally at least 800 °C, optionally at least 900 °C and optionally at least 1000 °C. Heating the precipitate comprising lithium to form the doped solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) may optionally comprise heating the precipitate comprising lithium to a temperature of no more than 1500 °C, optionally no more than 1400 °C, optionally no more than 1300 °C, optionally no more than 1200 °C, optionally no more than 1100 °C and optionally no more than 1000 °C.

[0029] The method may comprise separating the precipitate comprising lithium from an ambient liquid (such as an aqueous liquid), for example, using filtration.

[0030] The method may comprise drying the precipitate comprising lithium, optionally post-separation of the precipitate comprising lithium from an ambient liquid. Drying the precipitate comprising lithium may comprise heating the precipitate comprising lithium, optionally to a temperature of no more than 200 °C, optionally no more than 180 °C, optionally no more than 160 °C, optionally no more than 140 °C, optionally no more than 120 °C and optionally no more than 100 °C. Drying the precipitate comprising lithium may comprise heating the precipitate comprising lithium, optionally to a temperature of at least 60 °C, optionally at least 80 °C, optionally at least 100 °C and optionally at least 120 °C. Drying the precipitate comprising lithium may comprise subjecting the precipitate comprising lithium to reduced pressure.

[0031] All in all, the method of the first aspect of the invention may be or comprise a method of method of making a doped lithium lanthanum zirconium oxide, the method comprising the following steps in order: (a) contacting a first composition with a second composition (optionally at a pH of at least about 3.5), the first composition being in the form of an aqueous solution and comprising Zr, La and optionally one or more dopant species, the second composition being in the P037226WO1form of an aqueous solution or suspension and comprising one or more dopant species, thereby forming a first precipitate comprising the Zr, La and one or more dopant species; (b) contacting a (preferably aqueous or at least partially aqueous) solution comprising lithium ions with the first precipitate; (c) subsequently adding, to the mixture obtained in step (b), a source of anions (optionally carbonate) with which lithium forms an insoluble salt, thereby forming a second precipitate comprising lithium; and (d) heating (optionally calcining) the second precipitate to form the doped lithium lanthanum zirconium oxide.

[0032] Optionally, at least one species for incorporation into the doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) and optionally at least one dopant may be provided as a polyoxometalate. Optionally when the doped lithiated solid-state electrolyte material is or comprises a doped lithium lanthanum zirconium oxide, at least one species for incorporation into the doped lithium lanthanum zirconium oxide is provided as a polyoxometalate, optionally wherein at least one dopant species is provided as a polyoxometalate. Optionally, at least one dopant is not provided by a polyoxometalate. For example, if a dopant to be incorporated into the doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) is a metal, then the dopant may optionally be provided as a polyoxometalate. For example, the solid (optionally a precipitate) comprising one or more species for incorporation into the solid-state electrolyte material (preferably, a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) may comprise a polyoxometalate. Alternatively, the method may comprise forming the solid comprising one or more species for incorporation into the solid- state electrolyte material (preferably, a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide) from a solution comprising a polyoxometalate. A polyoxometalate is a polyatomic ion, usually but not always an anion, that comprises three or more metal oxyanions linked together by shared oxygen atoms to form a closed 3-dimensional framework. The metal is typically a transition metal. Such polyoxometalates may comprise one or more of niobium, molybdenum, tungsten, tellurium, tantalum and aluminium. Each polyoxometalate ion may P037226WO1comprise at least 3, optionally at least 4, optionally at least 5, optionally at least 6 and optionally at least 7 metal species. Each polyoxometalate ion may comprise no more than 300 metal species, optionally no more than 250, optionally no more than 200, optionally no more than 150, optionally no more than 100, optionally no more than 80, optionally no more than 60, optionally no more than 50, optionally no more than 40, optionally no more than 30, optionally no more than 20, optionally no more than 15, optionally no more than 14, optionally no more than 13, optionally no more than 12, optionally no more than 11, optionally no more than 10, optionally no more than 9, optionally no more than 8 and optionally no more than 7 metal species. For the avoidance of doubt, this is not the number of different metal species in the ion, but the number of metal atoms / ions in the polyoxometalate ion.

[0033] The polyoxometalate may have a Keggin structure, a Lindqvist structure or an Anderson-Evans structure, for example.

[0034] Optionally, the polyoxometalate may comprise one or more of [Nb 8- 6O19] , [Mo O ]6-, [TeNb O ]7-, [ [TeW O ]6-, [ (8-x)- 7 24 5 19 6 24 Nb6-xWxO19] , where x is an integer from 1 to 5, Nb W O ]5-, [Nb T-8 8- 12-7+ 3 3 19 3 a3O19] , [W12O40] , [W12O42] and [Al13O4(OH)24]

[0035] A plurality of species may be provided for incorporation into a doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide). One, more than one or all of those species, optionally including any dopants, may be provided in the solid that is contacted with lithium species, such as lithium ions. Alternatively, one or more than one of those species may be provided separately from said solid for example, in a solution or suspension to be contacted with said solid.

[0036] One or more species for incorporation into the doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) may comprise one or more of lanthanum, zirconium, aluminium, germanium and titanium. One or more of those species may be present in the solid that is contacted with the lithium species, optionally lithium ions, especially a (preferably aqueous or at least partially aqueous) solution comprising lithium ions. One or more of those species may be provided separately from said solid, for example, in a solution or suspension to be contacted with said solid.

[0037] One or more species for incorporation into the doped lithiated solid-state electrolyte material may comprise lanthanum and zirconium. One or more of those species may be P037226WO1present in the solid that is contacted with the lithium species, optionally lithium ions, especially a (preferably aqueous or at least partially aqueous) solution comprising lithium ions. One or more of those species may be provided separately from said solid, for example, in a solution or suspension to be contacted with said solid.

[0038] One or more species for incorporation into the doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) may comprise aluminium and germanium. One or more of those species may be present in the solid that is contacted with the lithium species, optionally lithium ions (preferably, an aqueous or at least partially aqueous solution comprising lithium ions). One or more of those species may be provided separately from said solid, for example, in a solution or suspension to be contacted with said solid.

[0039] One or more species for incorporation into the doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) may comprise lanthanum and titanium. One or more of those species may be present in the solid that is contacted with the lithium species, optionally lithium ions (preferably, an aqueous or at least partially aqueous solution comprising lithium ions). One or more of those species may be provided separately from said solid, for example, in a solution or suspension to be contacted with said solid.

[0040] The doped lithiated solid-state electrolyte material (preferably a doped lithium lanthanum zirconium oxide) optionally comprises one or more of lanthanum, zirconium, aluminium, germanium and titanium. For example, the doped lithiated solid-state electrolyte material may comprise lithium, aluminium and germanium, optionally in combination with phosphate. The doped lithiated solid-state electrolyte material may comprise lithium aluminium germanium phosphate. The doped lithiated solid-state electrolyte material may comprise LiAAlBGeC(PO4)D, where A=1.0-2.0, B=0.01-1.0, C=1.0-2.0 and D=2.0-4.0, optionally D=3. The doped lithiated solid-state electrolyte material may comprise lithium, aluminium and titanium, optionally in combination with phosphate. The doped lithiated solid-state electrolyte material may comprise lithium aluminium titanium phosphate. The doped lithiated solid-state electrolyte material may comprise LiAAlBTiC(PO4)D, where A=1.0-2.0, B=0.01-1.0, C=1.0-2.0 and D=2.0-4.0, P037226WO1optionally D=3. The doped lithiated solid-state electrolyte material may comprise lithium lanthanum titanate. The doped lithiated solid-state electrolyte material may comprise LiALaBTiCOD, where A=0.01-1.0, B=0.01-1.0, C=0.5-1.5 and D=2.0-4.0, optionally D=3.

[0041] For example, the lithiated solid-state electrolyte material optionally comprises lithium, lanthanum and zirconium. Preferably, the lithiated solid-state electrolyte material is or comprises a doped lithium lanthanum zirconium oxide. The doped lithiated solid-state electrolyte material may comprise lithium, lanthanum, zirconium and oxygen. The doped lithiated solid-state electrolyte material may comprise LiALaBZrCOD, where A=5.0-8.0, B=2.5-3.0, C=1.0-2.0 and D=11-12. A is optionally at least 5.5 and t least 5.8. A is optionally no more than 7.0 and optionally no more than 6.8. B is optionally at least 2.5 and optionally at least 2.8. C is optionally at least 1.3 and optionally at least 1.4. C is optionally no more than 1.8. D is optionally 12. For the avoidance of doubt, the doped lithiated solid-state electrolyte material will comprise dopants in addition to the lithium, lanthanum, zirconium and oxygen.

[0042] The statements above and below in relation to the method of the first aspect of the present invention all preferably pertain to doped lithium lanthanum zirconium oxide.

[0043] The one or more dopant species optionally comprises one or more of an alkali metal, an alkaline earth metal, a transition metal (for example, a Group 4, Group 5 or Group 6 species), a Group 13 species, a Group 15 species, a Group 16 species, a rare earth species and a lanthanide. This is particularly the case where the doped lithiated solid-state electrolyte material is a doped lithium lanthanum zirconium oxide.

[0044] The doped lithium lanthanum zirconium oxide may have a formula LiALaBZrCODXE, where A=5.0-8.0, B=2.5-3.0, C=1.0-2.0, D=11-12 and X is one or more dopants, and E is the total amount of dopant. E is optionally at least 0.01, optionally at least 0.05, optionally at least 0.1, optionally at least 0.15, optionally at least 0.2, optionally at least 0.25 and optionally at least 0.3. E is optionally no more than 1.0, optionally no more than 0.9, optionally no more than 0.8 and optionally no more than 0.75.

[0045] The one or more dopant species optionally comprises one or more of a transition metal, a Group 13 species, a Group 15 species and a Group 16 species. P037226WO1

[0046] The one or more dopant species optionally comprises one or more of an alkali metal, an alkaline earth metal, a Group 4 species, a lanthanide and a rare earth species.

[0047] The one or more dopant species optionally comprises one or more of an alkaline earth metal, a Group 4 species, a lanthanide and a rare earth species.

[0048] The one or more dopant species optionally comprises one or more of a transition metal, a Group 13 species, a Group 15 species and a Group 16 species, and in addition one or more of an alkali metal, an alkaline earth metal, a Group 4 species, a lanthanide and a rare earth species.

[0049] The one or more dopant species optionally comprises one or more of a transition metal, a Group 13 species, a Group 15 species and a Group 16 species, and in addition one or more of an alkaline earth metal, a Group 4 species, a lanthanide and a rare earth species.

[0050] Optionally, the doped lithium lanthanum zirconium oxide may have a formula LiALaBZrCODX1E1X2E2, where X1 represents one or more dopants comprising one or more of a transition metal, a Group 13 species, a Group 15 species and a Group 16 species, A, B, C and D are defined above, E1 represents the total amount of such dopants, X2 represents one or more dopants, each of which not being a transition metal, a Group 13 species, a Group 15 species and a Group 16 species, and E2 representing the total amount of such dopants. E1 is optionally at least 0.01, optionally at least 0.05, optionally at least 0.1, optionally at least 0.15, optionally at least 0.2, optionally at least 0.25 and optionally at least 0.3. E1 is optionally no more than 0.8, optionally no more than 0.7 and optionally no more than 0.6. E2 is optionally at least 0.01, optionally at least 0.05, optionally at least 0.08, optionally at least 0.1 and optionally at least 0.2. E2 is optionally no more than 0.5, optionally no more than 0.4 and optionally no more than 0.3. X2 optionally represents one or more dopant comprising one or more of an alkali metal, an alkaline earth metal, a lanthanide and a rare earth species.

[0051] The one or more dopant species optionally comprises one or more of Mo, Nb, Te, Al, Ga, Sb, W and Ta. Such dopants have been found to be advantageous for LLZO materials.

[0052] The one or more dopant species optionally comprises one or more of Hf, Ti, Sr, Ca, Ba, Mg, Ce, Sc, Y and Rb. Such dopants may be advantageous for LLZO materials, P037226WO1optionally in combination with other dopants, such as one or more of Nb, Te, Al, Ga, Sb, W and Ta.

[0053] In accordance with the Examples, the doped lithiated solid-state electrolyte material may be a doped lithium lanthanum zirconium oxide, wherein the one or more dopant species optionally comprises one or more of Nb, Te, Ta, Hf, Ti, Sr, Ca, Ba, Mg, Ce, Sc, Y, Al, Ga, Sb, W and Rb.

[0054] According to a second aspect of the invention, there is also provided a doped lithiated solid-state electrolyte material made in accordance with the method of the first aspect of the present invention. The doped lithiated solid-state electrolyte material of the second aspect of the present invention may comprise the features described above in relation to the method of the first aspect of the present invention. Preferably, the doped lithiated solid-state electrolyte material of the second aspect of the present invention is or comprises a doped lithium lanthanum zirconium oxide made, or makeable, using the method of the first aspect of the present invention.

[0055] According to a third aspect of the present invention, there is provided a method of making a doped lithium lanthanum zirconium oxide, the method comprising: contacting a lithium species (optionally lithium ions) with a solid (optionally a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the solid-state electrolyte material; forming a precipitate comprising lithium, optionally by providing a source of anions with which lithium may form an insoluble salt; and calcining the precipitate comprising lithium to form the doped lithium lanthanum zirconium oxide.

[0056] The method of the third aspect of the present invention may comprise any of the features of the method of the first aspect of the present invention. For example, one or more dopant species may comprise those dopant species mentioned above in relation to the method of the first aspect of the present invention. For example, one or more dopant species may be provided as a polyoxometalate. P037226WO1

[0057] According to a fourth aspect of the present invention, there is provided a composition for forming a lithiated solid-state electrolyte material, the composition comprising: a solid (optionally a precipitate) comprising species for incorporation into the solid-state electrolyte material, the species for incorporation into the solid-state electrolyte material comprising one or more dopants, the precipitate being substantially devoid of lithium species (optionally lithium ions); and a lithium species (optionally lithium ions, optionally dissolved in a solution). Preferably, the lithiated solid-state electrolyte material is or comprises a doped lithium lanthanum zirconium oxide. Preferably, the solid is or comprises a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, the solid being substantially devoid of lithium species. Preferably, the lithium species is or comprises lithium ions dissolved in aqueous (or at least partially aqueous) solution.

[0058] The composition of the fourth aspect of the present invention may comprise one or more features described above in relation to the method of the first aspect of the present invention. For example, the solid (optionally a precipitate) comprising species for incorporation into the solid-state electrolyte material may comprise the features described above in relation to the method of the first aspect of the present invention. The composition of the fourth aspect of the present invention may be a composition that is formed in the method of the first aspect of the present invention when the solution comprising lithium ions is contacted with the solid (optionally a precipitate) comprising species for incorporation into the solid-state electrolyte material. The composition of the fourth aspect of the present invention may particularly be formed in a method for producing doped LLZO.

[0059] Thus, the composition of the fourth aspect of the invention preferably is or comprises a composition for forming a doped lithium lanthanum zirconium oxide, the composition comprising: P037226WO1a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, the solid being substantially devoid of lithium species; and lithium ions dissolved in (preferably aqueous, or at least partially aqueous) solution.

[0060] Optionally, the composition of the fourth aspect of the invention comprises a source of anions with which lithium forms an insoluble salt. Optionally, the source of anions with which lithium forms an insoluble salt is or comprises a source of carbonate anions.

[0061] In accordance with a fifth aspect of the present invention, there is provided a two- part reaction mixture composition for forming a lithiated solid-state electrolyte material, the two-part reaction mixture comprising: a first part comprising a solid (optionally a precipitate) comprising species for incorporation into the solid-state electrolyte material, the species for incorporation into the solid-state electrolyte material comprising one or more dopants, the precipitate being substantially devoid of lithium species, optionally lithium ions; and a second part comprising a lithium species, optionally lithium ions. Preferably, the lithiated solid-state electrolyte material is or comprises a doped lithium lanthanum zirconium oxide. Preferably, the solid of the first part is or comprises a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, the solid being substantially devoid of lithium species. Preferably, the lithium species of the second part is or comprises lithium ions dissolved in (preferably aqueous, or at least partially aqueous) solution.

[0062] The composition of the fifth aspect of the present invention may comprise one or more features described above in relation to the method of the first aspect of the present invention, and / or one or more features described above in relation to the composition of the fourth aspect of the present invention. For example, the solid (optionally a precipitate) comprising species for incorporation into the solid-state electrolyte material may comprise the features described above in relation to the method of the first aspect of the present invention. The composition of the fifth aspect of the present invention may be a composition that is used in the method of the first aspect of the present invention. The P037226WO1composition of the fifth aspect of the present invention may particularly be useful in a method for producing doped LLZO.

[0063] Thus, the composition of the fifth aspect of the invention preferably is or comprises a two-part reaction mixture composition for forming a doped lithium lanthanum zirconium oxide, the two-part reaction mixture comprising: a first part comprising a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, the solid being substantially devoid of lithium species; and a second part comprising lithium ions dissolved in (preferably aqueous, or at least partially aqueous) solution.

[0064] Optionally, the composition of the fifth aspect of the invention is a three-part reaction mixture composition, further comprising: a third part comprising a source of anions with which lithium forms an insoluble salt. Optionally, the source of anions with which lithium forms an insoluble salt is or comprises a source of carbonate anions.

[0065] In accordance with a sixth aspect of the present invention, there is provided a composition for forming a lithiated solid-state electrolyte material, the composition comprising: a solid (optionally a precipitate) comprising species for incorporation into the solid-state electrolyte material, the species for incorporation into the solid-state electrolyte material comprising one or more dopants, the precipitate optionally comprising lithium; a lithium species (optionally lithium ions, optionally dissolved in a solution); and a source of carbonate ions.

[0066] The composition of the sixth aspect of the present invention may comprise one or more features described above in relation to the method of the first aspect of the present invention, and / or one or more features described above in relation to the compositions of the fourth and fifth aspects of the present invention.

[0067] It will, of course, be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa. P037226WO1

[0068] Embodiments of the present invention will now be described by way of example only. DETAILED DESCRIPTION

[0069] The sources of the reagents used in the Examples below are as follows: ZrOCl2.8H2O: Thermo Scientific A12342; La2O3: ACROS Organics 199160010; La(NO3)3.6H2O: VWR 24958.238; 37% HCl: VWR 20252-335; Na2CO3: Tata; K2CO3: VWR 26724.360; Nb2O5: Alfa Aesar 11365-35; Nb2O5.xH2O: CBMM; KOH: VWR 26668.365; K8[Nb6O19]: Nb2O5 or Nb2O5.xH2O was stirred in KOH solution at 90 – 180 °C until almost no further dissolution occurred, then any remaining solid was filtered off to leave a clear, pale-blue solution; LiOH.H2O: Alfa Aesar 43171-36; NH4HCO3: Merck 1.01131.5000; (NH4)2Zr(OH)2(CO3)2 solution: Sigma Aldrich 464597.250; (TBA)OH 40% solution : VWR 85738.180; 69% HNO3: VWR 20425.322; (ZrO2)2.CO2.xH2O: Alfa Aesar 43245.36 (NH4)6[Mo7O24].4H2O: VWR 21276.185; LiNO3: VWR 25029.268; Te(OH)6: Alfa Aesar 14197.09; Na2WO4.2H2O: HC Starck; Cs2CO3: Supplied by Dakram; Ta2O5: Alfa Aesar 14709.18; HfOCl2.8H2O: Alfa Aesar 11833.14; TiOSO4solution: Sigma Aldrich 495379- 1L; SrCl2.6H2O: Alfa Aesar 12494.36; CaCl2.2H2O: ACROS Organics 207780025 BaCl2.2H2O: VWR 21709.364; MgCl2.6H2O: Sigma Aldrich M9272-500G; CeCl3.7H2O: Alfa Aesar A12947.30; ScCl3.6H2O: Alfa Aesar 11218.03; YCl3.6H2O: ACROS Organics 199180500; Al(NO3)3.9H2O: Alfa Aesar 12360.A1; (NH4)10[H2W12O42].xH2O: HC Starck; (NH4)6[H2W12O40].xH2O: HC Starck; CO2: Air Liquide; K8Ta6O19.16H2O - Ta powder and KOH were heated together at 450 °C until a melt formed. The melt was then extracted into the minimum quantity of water to make a clear, colourless solution.; Rb2CO3: Sigma Aldrich 8.43858.0010; WO3.2H2O - Na2WO4.2H2O was slowly added to a room temperature solution of 20% HCl, and left to stir for 4 hours. The yellow precipitate formed was filtered off and dried in air.

[0070] Example 1 – MC06-081 – Li6.4La3Zr1.4Nb0.6O12via [Nb6O19]8- P037226WO1

[0071] Solution A was prepared by dissolving 128.9 g 37% HCl and 66.6 g ZrOCl2.8H2O in 200 ml DI water. Once fully dissolved, 71.1 g La2O3 was added and stirred to dissolve. The solution was diluted to 1.5 L with DI water. For the avoidance of doubt, DI water is deionized water.

[0072] Solution B was prepared by diluting 75.8 g of K8Nb6O19 solution (30.7% as K8Nb6O19.15H2O, 4.34% as KOH) to 500 ml with DI water, then adding 107.2 g K2CO3. The mixture was stirred until fully dissolved.

[0073] Solution A was added to Solution B at room temperature over the course of 1 hr. The mixture was aged for 40 minutes. The white precipitate formed was isolated by filtration and washed until the filtrate had a conductivity of < 500 µS.

[0074] The cake was then resuspended in a solution of 64.8 g LiOH.H2O in 500 ml DI water and agitated until resuspended. A solution of 61.0 g NH4HCO3in 300 ml DI water was added to the suspended cake over the course of 45 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.6O12. The crystal structure was confirmed to be cubic via XRD analysis. No impurities were observed. This example demonstrates that the doped LLZO may be produced by forming a precipitate comprising lanthanum, zirconium and niobium, contacting that precipitate with lithium ions and then adding a source of carbonate ions, with no observable impurities.

[0075] Example 2 – CO02-104 – Li6.4La3Zr1.4Nb0.6O12

[0076] 7.42 g of Nb2O5.xH2O was added into 16.87 g of 40% TBA-OH solution and diluted to 50 mL. TBA is (C4H9)4N+. The suspension was heated under reflux at 100 °C for 5.5 hours before being cooled to room temperature. The remaining solid was removed via vacuum filtration, leaving a solution containing (TBA)6Nb10O28.

[0077] Solution A was prepared by dissolving 12.7 g of 37% HCl and 6.59 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.00 g of La2O3was added and stirred to dissolve. The solution was then diluted to 150 mL. P037226WO1

[0078] Composition B was prepared by diluting 74.13 g of (TBA)6Nb10O28 solution (3.28 % as (TBA)6Nb10O28, 1.21 % as TBA-OH) to 100 mL with DI water. 8.54 g of Na2CO3 was added and stirred to dissolve, causing a white precipitate to form.

[0079] Solution A was added to Composition B over the course of 1 hour. The resultant white precipitate was aged for one hour before being isolated and washed via vacuum filtration.

[0080] The cake was resuspended in 50 mL of DI water and 6.19 g of LiOH.H2O was added and dissolved. Separately, 5.83 g of NH4HCO3 was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 10 hours. The material produced was pure cubic LLZO. This example demonstrates that the doped LLZO may be produced by forming a precipitate comprising lanthanum, zirconium and niobium, contacting that precipitate with lithium ions and then adding a source of carbonate ions, with no observable impurities. The niobium was provided as a polyoxometalate, in this case [Nb 6- 10O28] .

[0081] Example 3 – CO02-115A – Li6.4La3Zr1.4Nb0.6O12

[0082] Solution A was prepared by dissolving 12.7 g of 37% HCl and 6.59 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.00 g of La2O3was added and stirred to dissolve. The solution was then diluted to 150 mL.

[0083] Solution B was prepared by diluting 8.66 g of K8Nb6O19.15H2O (19.4% as K8Nb6O19.15H2O, 0.87% as KOH ) to 50 mL with DI water. 12.4 g of NH4HCO3 was added into the solution and stirred to dissolve. Note the use of hydrogen carbonate ions in solution B, compared to carbonate ions in Examples 1 and 2.

[0084] Solution A was added to solution B over the course of 1 hour. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0085] The cake was resuspended in 50 mL of DI water and diluted to 100 mL. 6.19 g of LiOH.H2O was added and dissolved. Separately, 5.83 g of NH4HCO3 was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was then calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a P037226WO1small La2O3 and La2Zr2O7 impurity. It is suspected that the impurities are an artefact of poor mixing during the experiment. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8-.

[0086] Example 4 – MC07-058C – Li6.4La3Zr1.4Nb0.6O12

[0087] Solution A was prepared by dissolving 12.2 g 37% HCl and 6.32 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 6.72 g La2O3 was added and stirred to dissolve. The solution was diluted to 100 mL with DI water.

[0088] Composition B was prepared by diluting 9.35 g of K8Nb6O19 solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 100 ml with DI water, then adding 3.86 g Na2CO3and 4.08 g KOH. The mixture was stirred until fully dissolved. A precipitate slowly formed on standing. Note the use of both carbonate anions and potassium hydroxide in solution B.

[0089] Solution A was added to Composition B at room temperature over the course of 1 hr. The white precipitate formed was isolated and washed by centrifugation, then resuspended in a solution of 6.01 g LiOH.H2O in 40 ml DI water. The suspension was agitated until homogenous. A solution of 5.66 g NH4HCO3 in 28 ml DI water was added to the suspended cake over the course of 40 minutes. The solid was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.6O12. The crystal structure was confirmed to be cubic via XRD analysis. No impurities were formed. The niobium was provided as a polyoxometalate, in this case [Nb O ]8- 6 19 .

[0090] Example 5 – MC07-060C – Li6.4La3Zr1.4Nb0.6O12

[0091] Solution A was prepared by dissolving 12.2 g 37% HCl and 6.33 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 6.72 g La2O3 was added and stirred to dissolve. The solution was diluted to 100 mL with DI water.

[0092] Solution B was prepared by diluting 9.34 g of K8Nb6O19 solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 100 ml with DI water, then adding 8.19 g KOH. The mixture was stirred until fully dissolved. Note the use of potassium hydroxide in solution B. P037226WO1

[0093] Solution A was added to Solution B at room temperature over the course of 1 hr. The white precipitate formed was isolated and washed by centrifugation, then resuspended in a solution of 6.01 g LiOH.H2O in 40 ml DI water. The suspension was agitated until homogenous. A solution of 5.66 g NH4HCO3in 28 ml DI water was added to the suspended cake over the course of 40 minutes. The solid was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.6O12. The crystal structure was confirmed to be cubic via XRD analysis. No impurities were observed. The niobium was provided as a polyoxometalate, in this case [Nb 8- 6O19] .

[0094] Example 6 – CO02-122A – Li6.4La3Zr1.4Nb0.6O12

[0095] Solution A was prepared by diluting 3.73 g of 69% HNO3with 4.85 mL of DI water to give a 30% solution.6.24 g of [ZrO2]2.CO2.xH2O (40.37 % as ZrO2) was added to this and the slurry heated to 50 °C to dissolve the solid, resulting in a ZrO(NO3)2solution. 18.6 g of La(NO3)3.6H2O was then dissolved in the solution with agitation. Note the use of zirconium and lanthanum nitrates.

[0096] Solution B was prepared by diluting 7.89 g of K8Nb6O19 solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 50 mL with DI water. 8.31 g of Na2CO3 was then dissolved in the solution with agitation.

[0097] Solution A was added to solution B over the course of 1 hour at room temperature. The resultant white precipitate was isolated and washed via centriguation before being reslurried in 50 mL of DI water. 6.19 g of LiOH.H2O was dissolved in the slurry. Separately, 5.83 g of NH4HCO3 was dissolved in 27 mL of DI water with agitation. The NH4HCO3solution was added into the slurry over the course of 40 minutes with agitation. The precipitate was the isolated by filtration before being dried in an oven at 110 °C. The dried solid was calcined at 900 °C for 12 hours. The crystal structure was confirmed to be cubic via XRD analysis with a small amount of La2Zr2O7 present. The niobium was provided as a polyoxometalate, in this case [Nb 8- 6O19] .

[0098] Example 7 – MC07-066C – Li6.4La3Zr1.4Nb0.6O12 P037226WO1

[0099] Solution A was prepared by dissolving 12.2 g 37% HCl and 6.72 g La2O3 in 20 ml DI water. The solution was diluted to 100 mL with DI water.

[0100] Solution B was prepared by diluting 13.09 g ammonium zirconium carbonate solution (13.6% as Zr) to 100 ml with DI water, then adding 4.63 g K2CO3.. The mixture was stirred until fully dissolved, then 9.33 g of K8Nb6O19 solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) was added. The solution remained clear and colourless. Note the use of ammonium zirconium carbonate in solution B.

[0101] Solution A was added to Solution B at room temperature over the course of 1 hr. The white precipitate formed was isolated and washed by centrifugation, then resuspended in a solution of 6.01 g LiOH.H2O in 40 ml DI water. The suspension was agitated until homogenous. A solution of 5.66 g NH4HCO3in 28 ml DI water was added to the suspended cake over the course of 40 minutes. The solid was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.6O12. The crystal structure was confirmed to be cubic via XRD analysis, with a small amount of La2Zr2O7 impurity. The niobium was provided as a polyoxometalate, in this case [Nb 8- 6O19]

[0102] Example 8 – MC07-025 – Li6.4La3Zr1.48Nb0.43Te0.09O12

[0103] K7[TeNb5O19] was prepared by adding 0.32 g Te(OH)6 to 8.53 g of a solution containing 1.35 g K8[Nb6O19] and 0.07 g KOH. The suspension was made to ~10 ml, then stirred and heated gently until a clear, colourless solution formed. The solution was allowed to cool then sealed in a vial for 3 days before use.

[0104] Solution A was prepared by dissolving 14.2 g 37% HCl and 7.83 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 7.38 g La2O3 was added and stirred to dissolve. The solution was diluted to 100 ml with DI water.

[0105] Solution B was prepared by adding the entire quantity of solution of K7[TeNb5O19] as prepared above and 9.72 g Na2CO3 to 100 ml H2O and dissolving to a clear, colourless solution.

[0106] Solution A was added to Solution B at room temperature over the course of 1 hr. The white precipitate formed was isolated by centrifugation, then resuspended in a solution of 7.57 g LiOH.H2O in 90 ml DI water and agitated until resuspended. The P037226WO1suspension was made to 150 ml. A solution of 7.13 g NH4HCO3 in 33 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.48Nb0.43Te0.09O12. The crystal structure was confirmed to be cubic via XRD analysis. La2O3 impurity was present, likely due to overcharge. The niobium and tellurium were provided as a polyoxometalate, in this case [TeNb5O19]7-.

[0107] Example 9 – MC07-058B – Li6.4La3Zr1.4Ta0.3Nb0.3O12

[0108] Nominal Cs8[Nb3.11Ta2.89O19] was made by mixing 30.11 g Cs2CO3, 7.71 g Ta2O5and 5.00 g Nb2O5by hand, then heated to 900 °C for 10 hrs. The cooled melt was extracted with water to give a pale blue, slightly turbid solution of total mass 110.5 g. This mixture will contain Lindqvist ions of the general formula [Nb6-xTaxO19]8-,where x is between 0 and 6. The majority of the ions will have x = 2, 3 and 4.

[0109] Solution A was prepared by dissolving 12.2 g 37% HCl and 6.33 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 6.72 g La2O3 was added and stirred to dissolve. Once dissolved, the solution was diluted to 100 ml with H2O.

[0110] Composition B was prepared by dissolving 23.26 g Cs2CO3and 12.12 g of a solution nominally containing 2.89 g Cs8[Nb3.11Ta2.89O19] and 1.56 g Cs2CO3in 90 ml H2O. The mixture was stirred until the Cs2CO3fully dissolved – a slight turbidity remained from the Cs8[Nb3Ta3O19].

[0111] Solution A was added to Composition B at room temperature over the course of 1 hr. The white precipitate formed was isolated and washed by centrifugation, then resuspended in a solution of 6.01 g LiOH.H2O in 40 ml DI water and agitated until resuspended. The suspension was made to 100 ml. A solution of 5.66 g NH4HCO3in 28 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.3Ta0.3O12. The crystal structure was confirmed to be cubic via XRD analysis. No impurities were observed. The tantalum and niobium were provided as a polyoxometalate, in this case [Nb3.11Ta2.89O19]-8.

[0112] Example 10 – CO02-79B Preparation of Li6.4La3Zr1.3Nb0.6Hf0.1O12P037226WO1

[0113] Solution A was prepared by dissolving 13.2 g of 37% HCl and 6.77 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.23 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.61 g of HfOCl2.8H2O was added and stirred to dissolve.

[0114] Solution B was prepared by diluting 7.45 g of K8Nb6O19.15H2O solution (19.4% as K8Nb6O19.15H2O, 0.87% as KOH) to 50 mL. 8.82 g of Na2CO3 added into the solution and stirred to dissolve.

[0115] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0116] The cake was resuspended in 50 mL of DI water and 5.83 g of LiOH.H2O was added and dissolved. Separately, 5.49 g of NH4HCO3was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a small amount of La O . The n 8- 2 3 iobium was provided as a polyoxometalate, in this case [Nb6O19] .

[0117] Example 11 – CO02-82A – Preparation of Li6.4La3Zr1.3Nb0.6Ti0.1O12

[0118] Solution A was prepared by dissolving 13.3 g of 37% HCl and 6.39 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.34 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 1.60 g of TiOSO4 solution (15 wt% TiOSO4, 50 wt% H2SO4) was added and stirred to dissolve.

[0119] Solution B was prepared by diluting 9.08 g of K8Nb6O19.15H2O solution (19.4% as K8Nb6O19.15H2O, 0.87% as KOH) to 50 mL. 10.50 g of Na2CO3added into the solution and stirred to dissolve.

[0120] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0121] The cake was resuspended in 50 mL of DI water and 5.90 g of LiOH.H2O was added and dissolved. Separately, 5.56 g of NH4HCO3was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white P037226WO1suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a small amount of La2O3. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8-

[0122] Example 12 - CO02-29 – Preparation of Li6.5La2.9Sr0.1Zr1.4Nb0.6O12:

[0123] Solution A was prepared by dissolving 12.9 g of 37% HCl and 6.88g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.10 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.40 g of SrCl2.6H2O was added and stirred to dissolve.

[0124] Composition B was prepared by diluting 10.19 g of K8Nb6O19.15H2O solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 50 mL with DI water. 8.34 g of Na2CO3was added and stirred to dissolve, causing a white precipitate to form.

[0125] Solution A was added to Composition B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for one hour before being isolated and washed via vacuum filtration.

[0126] The cake was resuspended in 50 mL of DI water and 5.97 g of LiOH.H2O was added and dissolved. Separately, 5.41 g of NH4HCO3was dissolved in 22 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 10 hours. The material produced was pure cubic LLZO. The niobium was provided as a polyoxometalate, in this case [Nb 8- 6O19] .

[0127] Example 13 – CO02-33 – Preparation of Li6.5La2.9Ca0.1Zr1.4Nb0.6O12:

[0128] Solution A was prepared by dissolving 13.0 g of 37% HCl and 7.02 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.14 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.22 g of CaCl2.2H2O was added and stirred to dissolve.

[0129] Composition B was prepared by diluting 10.25 g of K8Nb6O19.15H2O solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 50 mL with DI water. 8.39 g of Na2CO3was added and stirred to dissolve, causing a white precipitate to form. P037226WO1

[0130] Solution A was added to Composition B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0131] The cake was resuspended in 50 mL of DI water and 6.00 g of LiOH.H2O was added and dissolved. Separately, 5.65 g of NH4HCO3 was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 10 hours. The material produced was pure cubic LLZO. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8-.

[0132] Example 14 – CO02-39 – Preparation of Li6.75La2.75Ca0.25Zr1.4Nb0.5O12:

[0133] Solution A was prepared by dissolving 12.5 g of 37% HCl and 7.53 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 6.88 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.56 g of CaCl2.2H2O was added and stirred to dissolve.

[0134] Composition B was prepared by diluting 8.68 g of K8Nb6O19.15H2O solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 50 mL with DI water. 8.70 g of Na2CO3was added and stirred to dissolve, causing a white precipitate to form.

[0135] Solution A was added to Composition B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0136] The cake was resuspended in 50 mL of DI water and 6.25 g of LiOH.H2O was added and dissolved. Separately, 5.89 g of NH4HCO3 was dissolved in 28 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 10 hours. The material produced was pure cubic LLZO. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8-.

[0137] Example 15 – CO02-47 – Preparation of Li6.5La2.9Ba0.1Zr1.4Nb0.6O12

[0138] Solution A was prepared by dissolving 12.8 g of 37% HCl and 6.94 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.05 g of La2O3was added and stirred P037226WO1to dissolve. The solution was then diluted to 150 mL and 0.36 g of BaCl2.2H2O was added and stirred to dissolve.

[0139] Composition B was prepared by diluting 11.11 g of K8Nb6O19.15H2O solution (19.4% as K8Nb6O19.15H2O, 0.87% as KOH) to 50 mL with DI water. 8.57 g of Na2CO3 was added and stirred to dissolve, causing a white precipitate to form.

[0140] Solution A was added to Composition B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0141] The cake was resuspended in 50 mL of DI water and 5.95 g of LiOH.H2O was added and dissolved. Separately, 5.60 g of NH4HCO3was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 10 hours. The material produced was pure cubic LLZO. The niobium was provided as a polyoxometalate, in this case [Nb 8- 6O19] .

[0142] Example 16 – CO02-76A – Preparation of Li6.5La2.9Mg0.1Zr1.4Nb0.6O12

[0143] Solution A was prepared by dissolving 13.0 g of 37% HCl and 6.95 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.17 g of La2O3was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.31 g of MgCl2.6H2O was added and stirred to dissolve.

[0144] Solution B was prepared by dissolving 8.77 g of Na2CO3 in 50 mL of DI water. 2.19 g of K8Nb6O19.15H2O was added into the solution and stirred to dissolve.

[0145] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0146] The cake was resuspended in 50 mL of DI water and 6.02 g of LiOH.H2O was added and dissolved. Separately, 5.77 g of NH4HCO3 was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a small amount of Li2CO3. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8- P037226WO1

[0147] Example 17 – CO02-76B – Preparation of Li6.5La2.9Ce0.1Zr1.4Nb0.6O12

[0148] Solution A was prepared by dissolving 12.8 g of 37% HCl and 6.84 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.06 g of La2O3was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.56 g of CeCl3.7H2O was added and stirred to dissolve.

[0149] Solution B was prepared by dissolving 8.71 g of Na2CO3 in 50 mL of DI water. 2.16 g of K8Nb6O19.15H2O was added into the solution and stirred to dissolve.

[0150] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0151] The cake was resuspended in 50 mL of DI water and 5.88 g of LiOH.H2O was added and dissolved. Separately, 5.53 g of NH4HCO3 was dissolved in 26 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was pure cubic LLZO. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8-.

[0152] Example 18 – CO02-79C – Preparation of Li6.5La3Zr1.3Nb0.6Sc0.1O12

[0153] Solution A was prepared by dissolving 13.4 g of 37% HCl and 6.38 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.34 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.39 g of ScCl3.6H2O was added and stirred to dissolve.

[0154] Solution B was prepared by diluting 9.08 g of K8Nb6O19.15H2O solution (19.4% as K8Nb6O19.15H2O, 0.87% as KOH) to 50 mL. 8.76 g of Na2CO3 added into the solution and stirred to dissolve.

[0155] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0156] The cake was resuspended in 50 mL of DI water and 5.97 g of LiOH.H2O was added and dissolved. Separately, 5.62 g of NH4HCO3was dissolved in 27 mL of DI P037226WO1water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a small amount of La2O3. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8- .

[0157] Example 19 – CO02-82B – Preparation of Li6.4La2.9Y0.1 Zr1.4Nb0.6O12

[0158] Solution A was prepared by dissolving 12.9 g of 37% HCl and 6.88 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.10 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL and 0.46 g of Ycl3.6H2O was added and stirred to dissolve.

[0159] Solution B was prepared by diluting 9.09 g of K8Nb6O19.15H2O solution (19.4% as K8Nb6O19.15H2O, 0.87% as KOH) to 50 mL. 8.69 g of Na2CO3 added into the solution and stirred to dissolve.

[0160] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0161] The cake was resuspended in 50 mL of DI water and 5.91 g of LiOH.H2O was added and dissolved. Separately, 5.56 g of NH4HCO3was dissolved in 27 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO. The niobium was provided as a polyoxometalate, in this case [Nb6O19]8-.

[0162] Example 20 – MC07-018 – Li5.8Al0.4La3Zr2O12

[0163] [Al13O4(OH)24](NO3)7was prepared thus. 18.76 g Al(NO3)3.9H2O was dissolved in H2O to make a solution with volume 100 ml. The solution was heated to 50 °C, then 6.36 g Na2CO3 was added over the course of 70 minutes. The temperature was maintained at 50 °C until the solution was clear and colourless, then the solution was cooled to ambient. A solution of total mass 105.5 g was obtained. P037226WO1

[0164] Solution A was prepared by dissolving 11.60 g [Al13O4(OH)12](NO3)7 solution and 9.04 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 12.2 g 37% HCl and 6.72 g La2O3were added and stirred to dissolve. Once dissolved, the solution was diluted to 100 ml with H2O.

[0165] Solution B was prepared by dissolving 9.70 g Na2CO3 in 100 ml H2O. The mixture was stirred until fully dissolved.

[0166] Solution A was added to Solution B at room temperature over the course of 1 hr. The white precipitate formed was isolated by centrifugation, then resuspended in a solution of 5.60 g LiOH.H2O in 50 ml DI water and agitated until resuspended. The volume of the suspension was made to 100 ml. A solution of 5.28 g NH4HCO3in 30 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li5.8Al0.4La3Zr2O12. The crystal structure was confirmed to be cubic via XRD analysis. There was a minor LaAlO3 impurity.

[0167] Example 21 – MC07-009B – Li5.8Ga0.4La3Zr2O12

[0168] Solution A was prepared by dissolving 13.1 g 37% HCl and 9.67 g ZrOCl2.8H2O in 50 ml DI water. Once fully dissolved, 7.19 g La2O3was added and stirred to dissolve. Once dissolved, 4.56 g Ga(NO3)3solution (9.5% Ga, Alfa Aesar, R28G059) was added. The solution was diluted to 100 ml with H2O.

[0169] Solution B was prepared by dissolving 12.28 g Na2CO3 in 100 ml H2O. The mixture was stirred until fully dissolved.

[0170] Solution A was added to Solution B at room temperature over the course of 1 hr. The white precipitate formed was isolated by filtration and washed until the filtrate had a conductivity of < 500 µS.

[0171] The cake was then resuspended in a solution of 6.31 g LiOH.H2O in 50 ml DI water and agitated until resuspended. The volume of the suspension was made to 100 ml. A solution of 5.94 g NH4HCO3 in 30 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li5.8Ga0.4La3Zr2O12. The crystal structure was confirmed to be cubic via XRD analysis. P037226WO1

[0172] Example 22 - CO02-94C – Li6.4La3Zr1.4Te0.3O12

[0173] Solution A was prepared by dissolving 13.1 g of 37% HCl and 8.21 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.21 g of La2O3was added and stirred to dissolve. The solution was then diluted to 150 mL.

[0174] Solution B was prepared by dissolving 1.02 g of Te(OH)6 in 50 mL of DI water. 9.27 g of Na2CO3 was added into the solution and stirred to dissolve.

[0175] Solution A was added to solution B over the course of 1 hour. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0176] The cake was resuspended in 50 mL of DI water and 5.83 g of LiOH.H2O was added and dissolved. Separately, 5.49 g of NH4HCO3was dissolved in 26 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a small La2O3 impurity. Example 27 illustrates the production of a doped material without using a polyoxometalate to deliver a dopant species.

[0177] Example 23 – CO02-89C – Li6.4La3Zr1.4Sb0.6O12

[0178] Solution A was prepared by dissolving 13.0 g of 37% HCl and 6.70 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 7.15 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 150 mL.

[0179] Composition B was prepared by adding 2.17 g of NaSbO3.3H2O in 50 mL of DI water, resulting in a white suspension.9.19 g of Na2CO3 was added into the solution and stirred to dissolve.

[0180] Solution A was added to Composition B over the course of 1 hour. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0181] The cake was resuspended in 50 mL of DI water and 5.79 g of LiOH.H2O was added and dissolved. Separately, 5.45 g of NH4HCO3was dissolved in 26 mL of DI P037226WO1water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was cubic LLZO with a small La2O3impurity.

[0182] Example 24 – MC07-062C – Li6.4La3Zr1.7W0.3O12

[0183] Solution A was prepared by dissolving 4.3 g of 37% HCl and 8.35 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 2.40 g of La2O3 was added and stirred to dissolve. The solution was then diluted to 100 mL.

[0184] Composition B was prepared by dissolving 5.19 g KOH in 100 ml H2O. 1.17 g (NH4)10[H2W12O42].xH2O (89.1% as WO3) was added to form an off-white suspension.

[0185] Solution A was added to Composition B at room temperature over the course of 1 hr. The white precipitate formed was isolated by centrifugation.

[0186] The cake was then resuspended in a solution of 18.29 g LiNO3 in 40 ml DI water and agitated until resuspended. A solution of 18.29 g NH4HCO3 in 97 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.7W0.3O12. The crystal structure was confirmed to be cubic via XRD analysis, with a minor amount of La2O3 and Li2ZrO3 impurity. It is appreciated that the La charge is too low to be stoichiometric. This is because the LiHCO3 solution produced leaches a lot of Zr and W out of the precipitate. We arrived at this amount of La2O3 by essentially iterating to the appropriate value.

[0187] Example 25 - LT02-147 – Li6.4La3Zr1.4Nb0.6O12

[0188] Solution A was prepared by dissolving 266.1 g 37% HCl and 137.4 g ZrOCl2.8H2O in 775 ml DI water. Once fully dissolved, 146.6 g La2O3 was added and stirred to dissolve.

[0189] Composition B was prepared by diluting 137.1 g of K8Nb6O19 solution (31.6% as K8Nb6O19.15H2O, 5.44% as KOH) to 860 ml with DI water, then adding 168.5 g Na2CO3. A white precipitate formed. P037226WO1

[0190] Solution A was added to Composition B at room temperature over the course of 1 hr. The mixture was aged for 1 hr. The white precipitate formed was isolated by filtration and washed until the filtrate had a conductivity of < 800 µS.

[0191] The cake was then resuspended in a solution of 114.5 g LiOH.H2O in 850 ml DI water and agitated until resuspended. The total volume was made to 1750 ml. CO2 gas was sparged into the suspension for 75 minutes until the pH dropped to 11.50. The suspension was aged for approximately 45 minutes, with further CO2 added if the pH rose above 11.5. The suspension was then isolated by filtration and dried at 110 °C. A sample of the dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.6O12. The crystal structure was confirmed to be cubic via XRD analysis. There were no significant impurities. This method may be particularly effective because the solution from which the precipitate comprising lithium is removed is a solution of lithium carbonate, which may be reused without further purification. This therefore reduces the loss of lithium.

[0192] Example 26 – MC07-020 – Li6.4La3Zr1.4Nb0.6O12

[0193] Solution A was prepared by dissolving 12.2 g 37% HCl and 6.33 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 6.72 g La2O3was added and stirred to dissolve. Once dissolved, the solution was diluted to 100 ml with H2O.

[0194] Composition B was prepared by dissolving 8.64 g Na2CO3in 100 ml H2O. 1.10 g Nb2O5 (Alfa Aesar) was added to form an off-white suspension.

[0195] Solution A was added to Composition B at room temperature over the course of 1 hr. The white precipitate formed was isolated by centrifugation.

[0196] The cake was then resuspended in a solution of 6.02 g LiOH.H2O in 50 ml DI water and agitated until resuspended. The volume of the suspension was made to 100 ml. A solution of 5.66 g NH4HCO3 in 30 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Nb0.6O12. The crystal structure was confirmed to be cubic via XRD analysis. No significant impurities were observed.

[0197] Example 27 – MC07-062B – Li6.4La3Zr1.4Ta0.6O12P037226WO1

[0198] Solution A was prepared by dissolving 12.2 g 37% HCl and 7.68 g ZrOCl2.8H2O in 20 ml DI water. Once fully dissolved, 6.72 g La2O3 was added and stirred to dissolve. Once dissolved, the solution was diluted to 100 ml with H2O.

[0199] Composition B was prepared by dissolving 8.64 g Na2CO3in 100 ml H2O. 1.82 g Ta2O5 (Alfa Aesar) was added to form an off-white suspension.

[0200] Solution A was added to Composition B at room temperature over the course of 1 hr. The white precipitate formed was isolated by centrifugation.

[0201] The cake was then resuspended in a solution of 6.02 g LiOH.H2O in 50 ml DI water and agitated until resuspended. The volume of the suspension was made to 100 ml. A solution of 5.66 g NH4HCO3in 30 ml DI water was added to the suspended cake over the course of 40 minutes. The suspension was then isolated by filtration and dried at 110 °C. The dried solid was heated to 900 °C for 10 hrs to produce Li6.4La3Zr1.4Ta0.6O12. The crystal structure was confirmed to be cubic via XRD analysis, with a small amount of La2O3 impurity.

[0202] Example 28 – CO02-68 – Li6.4La3Zr1.4Ta0.6O12

[0203] Solution A was prepared by dissolving 9.0 g of 37% HCl and 4.63 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 4.95 g of La2O3was added and stirred to dissolve. The solution was then diluted to 112 mL.

[0204] Solution B was prepared by dissolving 5.90 g of Na2CO3 in 50 mL of DI water. 1.92 g of K8Ta6O19.16H2O was added and stirred to dissolve.

[0205] Solution A was added to solution B over the course of 1 hour and 40 minutes. The resultant white precipitate was aged for 1 hour before being isolated and washed via vacuum filtration.

[0206] The cake was resuspended in 50 mL of DI water and 4.46 g of LiOH.H2O was added and dissolved. Separately, 4.20 g of NH4HCO3was dissolved in 20 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was the calcined at 900 °C for 12 hours. The material produced was pure cubic LLZO with a small amount of La2O3. Due to weighing errors in this Example, Ta was undercharged during this reaction which is the likely cause of impurities. P037226WO1

[0207] Example 29 -MC07-068A – Preparation of Li6.65La2.875Rb0.125Zr1.4Nb0.6O12:

[0208] 9.22 g K8Nb6O19.15H2O was dissolved in 100 ml DI water to form a clear, colourless solution. 8.29 La(NO3)3.6H2O was dissolved in 50 ml DI water to form a clear, colourless solution. The lanthanum nitrate solution was added to the potassium hexaniobate solution over the course of 40 minutes, forming a thick white precipitate. The precipitate was washed and isolated by centrifugation, then resuspended in 15 ml DI water. 2.43 g Rb2CO3 was added and the suspension stirred until homogenous. The suspension was freeze dried, then calcined at 1000 °C for 10 hrs to form RbLaNb2O7. XRD analysis suggested the material was 80% pure, with the remaining material Rb2CO3.

[0209] Solution A was prepared by dissolving 9 ml of 36% HCl and 6.33 g of ZrOCl2.8H2O in 30 mL DI water. Once dissolved, 5.88 g of La2O3was added and stirred to dissolve. The solution was then diluted to 100 ml.

[0210] Composition B was prepared by diluting 5.44 g of K8Nb6O19.15H2O solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 100 mL with DI water. 1.13 g RbLaNb2O7 (80% pure, remaining material Rb2CO3) was added and stirred to form a homogenous suspension.7.28 g of Na2CO3was then added and stirred to dissolve, causing a white precipitate to form.

[0211] Solution A was added to Composition B over the course of 1 hour. The resultant white precipitate was isolated and washed via centrifugation.

[0212] The cake was resuspended in 40 mL of DI water and 6.18 g of LiOH.H2O was added and dissolved. Separately, 5.82 g of NH4HCO3 was dissolved in 28 mL of DI water and was added into the suspended cake over the course of 40 minutes. The white suspension was isolated via vacuum filtration and dried at 110 °C. The dried solid was then calcined at 900 °C for 10 hours. The crystal structure was confirmed to be cubic via XRD analysis.

[0213] The effect of pH to which the non-lithiated precursor material was subjected was investigated. Solution A was prepared by dissolving 7.01 g of ZrOCl2.8H2O in 30 mL of DI water. 12.7 g of 37% HCl was added into the solution before 7.01 g of La2O3 was dissolved in the solution with agitation. The solution was then diluted to 150 mL with DI water. P037226WO1

[0214] Solution B was prepared by diluting 7.91 g of K8Nb6O19 solution (21.3% as K8Nb6O19.15H2O, 3.87% as KOH) to 50 mL with DI water. 8.12 g of Na2CO3 was dissolved in the solution with agitation.

[0215] Solution A was added to solution B over the course of 1 hour at room temperature. The pH of the reaction was then adjusted to a desired value from 3.5 to 4.5 using 37% HCl. Once a stable pH had been reached, the precipitate was isolated and washed via centrifugation before being resuspended in 50 mL of DI water.

[0216] 6.20 g of LiOH.H2O was dissolved in the slurry and the total volume of the slurry was made up to 100 mL with DI water. Separately, 5.84 g of NH4HCO3 was dissolved in 27 mL of DI water with agitiation. The NH4HCO3solution was added into the slurry over the course of 40 minutes with agitation. The precipitate was isolated by filtration before being dried in an oven at 110 °C. The dried solid was calcined at 900 °C for 12 hours.

[0217] Cubic lithium lanthanum zirconium niobium oxide (LLZNO) was formed, without impurities, when the pH was 4.0, 4.2, 4.4 and 4.5. Cubic lithium lanthanum zirconium niobium oxide (LLZNO) was formed, with small amounts of impurities, when the pH was 3.6, 3.7.3.8 and 3.9. No cubic LLZNO was formed when the pH was 3.5.

[0218] The Examples above describe many examples of embodiments of methods in accordance with first and third aspects of the present invention, and of doped LLZO in accordance with the second aspect of the present invention. The Examples above also describe many examples of embodiments of compositions in accordance with the fourth aspect of the present invention, particularly in relation to when the solution A and composition / solution B had been mixed together to form a precipitate, which was in the presence of lithium ions. The precipitate formed from mixing solution A and composition / solution B would, at least in the first instance, be substantially devoid of lithium ions.

[0219] The Examples above also describe many examples of embodiments of compositions in accordance with the fifth aspect of the present invention, particularly in relation to when the solution A and composition / solution B had been mixed together to form a precipitate, which in this case would be a first part of a two-part reaction P037226WO1composition. A solution of lithium ions would form the second part of the two-part reaction composition.

[0220] The Examples above also describe many examples of embodiments of compositions in accordance with the sixth aspect of the present invention. In this connection, mixing of solution A and composition / solution B would form the precipitate, which may optionally comprise lithium. The composition also comprises lithium ions and a source of carbonate ions, such as carbon dioxide.

[0221] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0222] The many Examples above demonstrate that lithiated solid-state electrolyte materials, such as lithium lanthanum zirconium oxide, may be doped with a wide variety of dopants. Those skilled in the art will realise that other dopants may be used.

[0223] The many Examples above relate to the production of doped lithium lanthanum zirconium oxides. Those skilled in the art will realise that the teaching of these many examples can also be applied to other doped lithiated solid-state electrolyte materials, such as doped lithium aluminium germanium phosphates, doped lithium aluminium titanium phosphates and doped lithium lanthanum titanates.

[0224] Many of the Examples above demonstrate the use of polyoxometalates as a source of one or more dopants. Those skilled in the art will realise that other sources of dopants may be used.

[0225] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some P037226WO1embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments. P037226WO1

Claims

CLAIMS 1. A method of making a doped lithium lanthanum zirconium oxide, the method comprising: contacting a solution comprising lithium ions with a solid, the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide; forming a precipitate comprising lithium; and heating the precipitate comprising lithium to form the doped lithium lanthanum zirconium oxide.

2. The method of claim 1, wherein the step of forming a precipitate comprising lithium is or comprises: subsequent to the contacting step, providing a source of anions with which lithium forms an insoluble salt, thereby forming the precipitate comprising lithium.

3. The method of claim 2, wherein the source of anions is or comprises a source of carbonate anions.

4. The method of any preceding claim, wherein the solution comprising lithium ions is an aqueous or partially aqueous solution.

5. The method of any preceding claim, comprising forming the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide.

6. The method of claim 5, wherein forming the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide comprises mixing at least two solutions, at least one of which comprises the one or more dopant species for incorporation into the solid- state electrolyte material.

7. The method of claim 5 or claim 6, wherein forming the solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide takes place at a pH of at least about 3.

5. P037226WO18. The method of any preceding claim, wherein forming the precipitate comprising lithium comprises (i) contacting the solution comprising lithium ions with the solid (optionally, a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, and subsequently providing a source of carbonate ions; (ii) contacting the solid (optionally, a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide with a source of carbonate ions, and subsequently providing the solution comprising lithium ions; or (iii) contemporaneously contacting the solution comprising lithium ions and a source of carbonate ions with the solid (optionally, a precipitate) comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide.

9. The method of any preceding claim, wherein at least one species for incorporation into the doped lithium lanthanum zirconium oxide is provided as a polyoxometalate, optionally wherein at least one dopant species is provided as a polyoxometalate.

10. The method of claim 9 when dependent on claim 6, wherein the at least one of the two solutions comprises a polyoxometalate.

11. The method of any preceding claim, wherein the doped lithium lanthanum zirconium oxide comprises one or more of aluminium, germanium and titanium.

12. The method of any preceding claim, wherein the one or more dopant species comprises one or more of an alkali metal, an alkaline earth metal, a transition metal (optionally a Group 4, 5 or 6 species), a Group 13 species, a Group 15 species, a Group 16 species, a rare earth species and / or a lanthanide.

13. The method of claim 12, wherein the one or more dopant species comprises one or more of a transition metal, a Group 13 species, a Group 15 species and / or a Group 16 species.

14. The method of claim 12 or claim 13, wherein the one or more dopant species further comprises one or more of an alkali metal, an alkaline earth metal, a Group 4 species, a lanthanide and / or a rare earth species. P037226WO115. A doped lithium lanthanum zirconium oxide made, or makeable, using the method of any preceding claim.

16. A composition for forming a doped lithium lanthanum zirconium oxide, the composition comprising: a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, the solid being substantially devoid of lithium species; and lithium ions dissolved in solution.

17. The composition of claim 16, further comprising a source of anions with which lithium forms an insoluble salt.

18. The composition of claim 17, wherein the source of anions with which lithium forms an insoluble salt is or comprises a source of carbonate anions.

19. The composition of any one of claims 16 to 18, wherein the lithium ions dissolved in solution are dissolved in an aqueous solution or in a partially aqueous solution.

20. A two-part reaction mixture composition for forming a doped lithium lanthanum zirconium oxide, the two-part reaction mixture comprising: a first part comprising a solid comprising lanthanum, zirconium and one or more dopant species for incorporation into the doped lithium lanthanum zirconium oxide, the solid being substantially devoid of lithium species; and a second part comprising lithium ions dissolved in solution.

21. The reaction mixture composition of claim 20, which is a three-part reaction mixture composition, further comprising: a third part comprising a source of anions with which lithium forms an insoluble salt.

22. The reaction mixture composition of claim 21, wherein the source of anions with which lithium forms an insoluble salt is or comprises a source of carbonate anions.

23. The reaction mixture composition of any one of claims 20 to 22, wherein the lithium ions dissolved in solution are dissolved in an aqueous solution or in a partially aqueous solution. P037226WO1