Transition metal oxyfluorides

Abstract

The present invention relates to novel transition metal oxyfluoride compounds and methods for manufacturing said novel transition metal oxyfluorides. The inventors have demonstrated that by treating the transition metal oxides with a fluorine containing gas the corresponding transition metal oxyfluoride compounds are obtained.

Description

[0001] Transition metal oxyfluorides

[0002] TECHNICAL FIELD

[0003] This invention relates to a transition metal oxyfluoride compounds and a method for synthesizing transition metal oxyfluoride compounds.

[0004] BACKGROUND

[0005] As the development of small and lightweight electronic products, electronic devices, communication devices and the like has advanced rapidly and a need for electric vehicles has widely emerged with respect to environmental issues, there is a demand for improvement of performance of secondary batteries used as power sources for these products. Among these, a lithium secondary battery has come into the spotlight as a high-performance battery due to a high energy density and a high reference electrode potential.

[0006] During the charging process of a secondary battery, lithium ions are removed from the cathode, transported through the electrolyte, and are inserted into the anode while electrons are removed from the cathode and injected into the anode through an external circuit (charger). During the use or discharge of a secondary battery, lithium ions are removed from the anode, transported through the electrolyte, and are inserted into the cathode, while electrons flow through an external circuit to provide electric work.

[0007] Present high energy density battery systems are based on layered oxides targeting high voltage redox activity on Co and Ni. However, the use of Co leads to increased costs. The Co quantities may be lowered in favor of higher Ni quantities. However higher nickel content in battery systems present its own cost issues as well as certain manufacturing complications.

[0008] Mixed-anion transition metal oxyfluorides offer the combined advantages of fluorides and the beneficial effects of oxides achieving improved capacity, high voltage, good conductivity and good cycling stability. Oxygen-fluorine substitution can be employed to manipulate the physiochemical properties of those corresponding transition metal oxides and / or fluorides for rechargeable batteries, as cathode and / or anode materials, achieving improved electrochemical performances. However, it is still a challenging task to develop facile procedures to produce transition metal oxyfluorides, particularly difficult on a large scale and with high purity. O2F is disclosed as a promising transition metal oxyfluoride for cathode applications in lithium-ion batteries, and TiOFz and NbOzF are explored as anode materials (Deng Da, ChemNanoMat, vol.3, no 3)

[0009] Recently, important understandings have been made in the oxide space that enlarges the search space of high energy density cathode materials. Specifically, cation- disordered lithium transition metal oxides, which were generally considered electrochemically inactive due to limited Li diffusion by their disordered structure, can be promising cathode materials if provided with enough Li excess. However, cation disorder or cation mixing still presents numerous difficulties and challenges in providing high energy density cathode materials. For instance, oxygen oxidation, which is often necessary to achieve a high capacity from the disordered material, can trigger oxygen loss via lattice densification, which can lead to resistive surface layers and further add unwanted impedance to the cathode. Reported strategies for improving the stability of disordered rock salt materials is fluorination of these material resulting in fluorine substituted cation-disordered lithium metal oxides having improved electrochemical performances for use as cathode material (see for example WO 2018 / 187531 Al). However, these fluorine substituted cation- disordered lithium metal oxides are often synthesized by mixing the transition metal precursors with the fluorine source, often being LiF. Other examples are nanocomposites of LiF-MnO obtained through planetary ball milling of MnO and LiF (Jung, S.-K. et al, Nat. Energy 2017, 2, 16208). However, it is clear that through this reaction a composite of MnO and LiF is obtained and no new fluorinated transition metal compound is produced.

[0010] Hence, there remains a need to provide a fluorinated transition metal oxide precursor, which can be used as a precursor component suitable for manufacturing cathode active material having the disordered rock salt structure.

[0011] It is an object of the present invention to provide a transition metal oxyfluoride compounds.

[0012] It is a further object of the present inventor to provide a method for manufacturing a transition metal oxyfluorides. SUMMARY OF THE INVENTION

[0013] In a first aspect an object of the invention is achieved by providing a transition metal oxyfluoride compound according to formula (I)

[0014] MWy (I), wherein M1is a transition metal, wherein 0 < x < 2, and wherein 0 < y < 2.

[0015] The present inventors have surprisingly found that by treating a transition metal oxide with a fluorine containing gas the corresponding transition metal oxyfluoride compound is obtained. These transition metal oxyfluoride compounds have not been reported before according to the present inventors. For example, there are only two known manganese oxyfluoride compounds, which not only display high oxidation numbers but are both either explosive or very unstable and difficult to synthesize: MnzOzFg, which requires an O2 / F2 atmosphere at 3000 bars for its synthesis and decomposes spontaneously under air at room temperature, releasing corrosive HF gas (Muller, J. Fluor. Chem. 1981, 17, 409); and MnChF, which is a shock-sensitive compound, explosive at room temperature (A. Engelbrecht, A. V. Grosse, J. Am. Chem. Soc. 1954, 76, 2042). Another example of a known transition metal oxyfluoride is TiOF2, obtained after treating TiO2 with molecular fluorine gas (Louvain et al, J. Mater. Chem. A, 2014, 2, 15308). However, in this method stoichiometric amounts of fluorine gas (F2) are used and the fluorine insertion into TiO2 occurs at atmospheric pressure.

[0016] Without wishing to be bound by any theory, the present inventors believe that the under-stochiometric fluorination (i.e. introducing an amount of moles of fluorine less than the amount of moles of transition metal present in the transition metal oxide) results in an insertion of fluorine in the transition metal oxide and, with higher amounts of fluorine, a replacement of oxygen with fluorine within the transition metal oxide. The present invention is in sharp contract with the known over-stochiometric fluorination of transition metal oxides with F2 leading to a complete loss of oxygen present in the transition metal oxide, such as the fluorination of MnO2 to MnFs, (J. Chem. Soc. 1950, 1622-1624). In a second aspect the present invention provides a method for manufacturing a transition metal oxyfluoride compound.

[0017] DETAILED DESCRIPTION

[0018] In the drawings and the following detailed description, preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. To the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description and accompanying drawings.

[0019] The term "comprising", as used herein and in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to compositions consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the composition are A and B. Accordingly, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0020] X-Ray diffraction (XRD) as referred to herein, refers to XRD experiments performed on a Panalytical X-Pert Pro diffractometer equipped with a Cu Koi source and a linear X'celerator detector. Preferably, the total counting time was 60 min and the angle step size was 0.033 ° in the 2-theta 10-70 ° range.

[0021] Transition metal oxyfluoride compounds

[0022] In a first aspect the present invention concerns a transition metal oxyfluoride compound according to formula (I)

[0023] M^xFy (I), wherein M1is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Ti, Al and combinations thereof, wherein 0 < x < 2, and wherein 0 < y < 2.

[0024] In highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein M1is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations of at least two of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and Ti; preferably M1is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations thereof; more preferably M1is Mn, Ni, Co or combinations thereof; most preferably M1is Mn, Ni or Co. In highly preferred embodiments the transition metal oxyfluoride compound is according to formula (I), wherein M1is Mn.

[0025] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein M1is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations thereof, preferably M1is Mn, Ni, Co or combinations thereof; more preferably M1is Mn, Ni or Co, most preferably M1is Mn; wherein 0 < x < 2, preferably 0.01 < x < 1.99; and wherein 0 < y < 2, preferably 0.01 < y < 1.99.

[0026] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.1 < x < 1.9, preferably 0.5 < x < 1.7, more preferably 0.9 < x < 1.5.

[0027] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.05 < y < 1.9, preferably 0.1 < y < 1.7, more preferably 0.2 < y < 1.4.

[0028] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.1 < x < 1.9, preferably 0.5 < x < 1.7, more preferably 1.0 < x < 1.5; and wherein 0.05 < y < 1.9, preferably 0.1 < y < 1.7, more preferably 0.2 < y < 1.4. As appreciated by the skilled person the following transition metal oxyfluoride compounds fall within the scope of the present invention: MzOzxFzy, MsChxFsy, etc.

[0029] The present inventors contemplate that the addition of small amounts of other materials during synthesis in such a way that the general formula of the resulting metal oxyfluoride is no longer respected; but wherein the changes do not materially affect the basic and novel characteristic(s) of the metal oxyfluoride of the invention is possible. Such modifications are considered within the scope of the general formula for the purposes of the present invention. For example, the transition metal oxyfluoride compound according to formula (I) may comprise small amounts of M', wherein M' is any element different from M1, 0 and F; preferably M' is selected from the group consisting of Al, As, B, Ba, Ca, Ce, Mg, S, Si, Sr, Ti, Y, W and Zn; more preferably M' is selected from the group consisting of Al, As, B, Ba, Ca, Ce, Mg, S, Si, Sr, Y, W, Zn . In the context of the present invention small amounts of M' mean that the transition metal oxyfluoride compound according to formula (I) comprise less than 5 mol% of M' relative to M1, preferably less than 1 mol% of M' relative M1, more preferably less than 0.1 mol% of M' relative M1. In certain preferred embodiment the transition metal oxyfluoride compound according to formula (I) is substantially free of M'.

[0030] In certain highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < 2, and wherein 0 < y < l or l < y < 2.

[0031] Worded differently, the transition metal oxyfluoride is according to formula (I), wherein 0 < x < 2, wherein 0 < y < 2 and y 1.

[0032] In certain highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < l or l < x < 2, and wherein 0 < y < l or l < y < 2.

[0033] Worded differently, the transition metal oxyfluoride is according to formula (I), wherein 0 < x < 2 and x 1, and wherein 0 < y < 2 and y 1. In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < 1, preferably 0.1 < x < 0.9, more preferably 0.2 < x < 0.8, and wherein 0 <y < l orl < y < 2.

[0034] In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < 2, preferably 0 < x < l orl <x < 2, and wherein 0 < y < 1, preferably 0.1 < y < 0.9, more preferably 0.2 < y < 0.85.

[0035] In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < 1, preferably 0.1 < x < 0.9, more preferably 0.2 < x < 0.8, and wherein 0 < y < 1, preferably 0.1 < y < 0.9, more preferably 0.2 < y < 0.85.

[0036] In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 1 < x < 2, preferably 1.1 < x < 1.9, more preferably 1.2 < x < 1.8, and wherein 0 < y < 2, preferably 0 < y < l orl <y < 2.

[0037] In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < 2, preferably 0 <x < l orl < x < 2, and wherein 1 < y < 2, preferably 1.1 < y < 1.9, more preferably 1.2 < y < 1.85.

[0038] In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 1 < x < 2, preferably 1.1 < x < 1.9, more preferably 1.2 < x < 1.8, and wherein 1 < y < 2, preferably 1.1 < y < 1.9, more preferably 1.2 < y < 1.85.

[0039] In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0 < x < 1, preferably 0.1 < x < 0.9, more preferably 0.2 < x < 0.8, and wherein 1 < y < 2, preferably 1.1 < y < 1.9, more preferably 1.2 < y < 1.85. In certain more highly preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 1 < x < 2, , preferably 1.1 < x < 1.9, more preferably 1.2 < x < 1.8, and wherein 0 < y < 1, preferably 0.1 < y < 0.9, more preferably 0.2 < y < 0.85.

[0040] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.8 < x < 1.2, preferably wherein 0.9 < x < 1.1, more preferably wherein 0.99 < x < 1.01, most preferably x is about 1.

[0041] In certain preferred embodiments the transition metal oxyfluoride compound is according to formula (I), wherein 0.1 < y < 0.9, preferably wherein 0.15 < y < 0.8, more preferably wherein 0.2 < y < 0.85.

[0042] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.8 < x < 1.2, preferably wherein 0.9 < x < 1.1, more preferably wherein 0.99 < x < 1.01, most preferably x is about 1; and wherein 0.1 < y < 0.9, preferably wherein 0.15 < y < 0.8, more preferably wherein 0.2 < y < 0.85.

[0043] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I)a-c

[0044] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.5 < x < 1.9, preferably wherein 0.9

[0045] < x < 1.7, more preferably wherein 1.1 < x < 1.5.

[0046] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.1 < y < 1.9, preferably wherein 0.2

[0047] < y < 1.7, more preferably wherein 0.4 < y < 1.4. In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.5 < x < 1.9, preferably wherein 0.9 < x < 1.7, more preferably wherein

[0048] 1.1 < x < 1.5; and wherein 0.1 < y < 1.9, preferably wherein 0.2 < y < 1.7, more preferably wherein 0.4 < y < 1.4.

[0049] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I)d-h, preferably according to formula (I)d-g

[0050] In a highly preferred embodiment, the transition metal oxyfluoride compound according to formula (I) is amorphous. As appreciated by the skilled person the morphology of the transition metal oxyfluoride can be determined through X-Ray diffraction (XRD).

[0051] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.1 < y < 0.9, preferably wherein 0.2 < y < 0.8, more preferably wherein 0.25 < y < 0.85; wherein 0.8 < x < 1.2, preferably wherein 0.9 < x < 1.1, more preferably wherein

[0052] 0.99 < x < 1.01, most preferably x is about 1; and wherein the transition metal oxyfluoride compound is amorphous.

[0053] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I)a-c, wherein the transition metal oxyfluoride compound is amorphous. In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein 0.5 < x < 1.9, preferably wherein 0.9 < x < 1.7, more preferably wherein 1.1 < x < 1.5; wherein 0.1 < y < 1.9, preferably wherein 0.2 < y < 1.7, more preferably wherein 0.4 < y < 1.4; and wherein the transition metal oxyfluoride compound is amorphous.

[0054] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I)d-h, wherein the transition metal oxyfluoride compound is amorphous.

[0055] In certain preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein M1is Ti, wherein 0 < x < 2, preferably 0.01 < x < 1.99; and wherein 0 < y < 2, preferably 0.01 < y < 1.99.

[0056] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein M1is Ti, and wherein 0.1 < x < 1.9, preferably 0.5 < x < 1.7, more preferably 0.9 < x < 1.5.

[0057] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein M1is Ti, wherein 0.05 < y < 1.9, preferably 0.1 < y < 1.7, more preferably 0.2 < y < 1.4.

[0058] In preferred embodiments of the invention the transition metal oxyfluoride compound is according to formula (I), wherein M1is Ti, wherein 0.1 < x < 1.9, preferably 0.5 < x < 1.7, more preferably 1.0 < x < 1.5; and wherein 0.05 < y < 1.9, preferably 0.1 < y < 1.7, more preferably 0.2 < y < 1.4. Method for manufacturing

[0059] In a second aspect the invention provides a method for manufacturing a transition metal oxyfluoride compound comprising the following steps: i) providing a transition metal oxide, ii) heating the transition metal oxide to at least 100 °C, and iii) treating the heated transition metal oxide with a fluorine-containing gas thereby affording a transition metal oxyfluoride compound.

[0060] As appreciated by the skilled person the heated transition metal oxide is treated with a fluorine-containing gas at a temperature defined in step ii). Worded differently, the heated transition metal oxide is treated with a fluorine-containing gas at at least 100 °C, which is the temperature defined in step ii).

[0061] In preferred embodiments of the method the amount of fluorine present in the fluorine-containing gas for treating the heated transition metal oxide is defined as a ratio n(F) / n(M2) (mol / mol), wherein n(F) represents the amount of moles fluor present in the fluorine containing gas, and wherein n(M2) represents the amount of moles transition metal present in the transition metal oxide, wherein the ratio n(F) / n(M2) (mol / mol) is between 0.01 and 1.99.

[0062] Preferably, the ratio n(F) / n(M2) (mol / mol) is between 0.01 and 0.99 or 1.01 and 1.99, more preferably between 0.1 and 0.95 or between 1.1 and 1.9, most preferably between 0.2 and 0.9 or between 1.2 and 1.5.

[0063] In certain highly preferred embodiments of the method the amount of fluorine present in the fluorine-containing gas is defined as the ratio n(F) / n(M2) (mol / mol), wherein the ratio n(F) / n(M2) (mol / mol) is between 0.01 and 0.99, preferably between 0.1 and 0.95, more preferably between 0.2 and 0.9.

[0064] In certain more preferred embodiments the amount of fluorine present in the fluorine-containing gas is defined as the ratio n(F) / n(M2) (mol / mol) is between 0.2 and 0.99, more preferably between 0.4 and 0.95, more preferably between 0.45 and 0.9. In certain embodiments of the method the ratio n(F) / n(M2) (mol / mol) is between 1.01 and 1.99, preferably between 1.1 and 1.9, more preferably between 1.2 and 1.5.

[0065] In a preferred embodiment of the method the transition metal oxide is according to formula (II):

[0066] M2aOb (II), wherein M2is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Ti, Al and combinations thereof; and wherein 0 < a < 4 and 0 < b < 5.

[0067] In highly preferred embodiments of the method the transition metal oxide is according to formula (II), wherein M2is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations of at least two of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Ti; preferably M2is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations thereof; more preferably M2is Mn, Ni, Co or combinations thereof; most preferably M2is Mn, Ni or Co. In highly preferred embodiments the transition metal oxide is according to formula (II), wherein M2is Mn.

[0068] In certain preferred embodiments the transition metal oxide is according to formula (II), wherein M2is Ti.

[0069] In preferred embodiments of the method the transition metal oxide is according to formula (II), wherein M2is selected from the group consisting of Mn, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations thereof, preferably M2is Mn, Ni, Co or combinations thereof; more preferably M2is Mn, Ni or Co, most preferably M2is Mn; wherein 0 < a < 4, preferably 0 < a < 3, and wherein 0 < b < 5, preferably 0 < b < 4. In preferred embodiments of the method the transition metal oxide is according to formula (II), wherein a is about 1, 2 or 3. In preferred embodiments of the method the transition metal oxide is according to formula (II), wherein b is about 1, 2 or 3 or 4. In certain preferred embodiments of the method the transition metal oxide is according to formula (II), wherein a is about 1, 2 or 3 and wherein b is about 1, 2 or 3 or 4.

[0070] In highly preferred embodiments of the method the transition metal oxide is selected from the group consisting of MnO, MnOz, MnzCh, MnsCU, MnOOH, CoO, CO2O3, CO3O4 and combinations thereof, preferably the transition metal oxide is selected from the group consisting of MnO, MnOz, MnzOs, Mn3O4, MnOOH and combinations thereof, more preferably the transition metal oxide is MnO, MnzOs or Mn3O4. The transition metal oxide may occur in several polymorphic forms, such as a, p- or y-MnOOH, and the present method of the invention is not limited to a specific polymorphic form of the transition metal oxide. As appreciated by the skilled person the transition metal oxide may be commercially available, such as MnO, or may be synthesized by known synthetic strategies in the art, such as MnzOs which is obtained after heating MnO for 600 °C for 24 hours.

[0071] In certain preferred embodiments of the method the transition metal oxide is selected from the group consisting of TiOz, TiO, TizOs and combinations thereof, preferably the transition metal oxide is TiOz, TiO, TizOs, more preferably the transition metal oxide is TiOz.

[0072] Preferred embodiments of the method are provided, wherein heating the transition metal oxide to at least 110 °C, preferably at least 120 °C, more preferably at least 125 °C. Preferred embodiments of the method is wherein heating the transition metal oxide to at most 1000 °C, preferably at most 500 °C, more preferably at most 300 °C. Preferred embodiments of the method are wherein heating the transition metal oxide to a range of 110 to 1000 °C, preferably a range of 120 to 500 °C, more preferably a range of 125 to 300 °C.

[0073] Certain preferred embodiments of the method are provided, wherein the transition metal oxide is MnO and wherein heating the transition metal oxide to a range of 110 to 250 °C, preferably a range of 120 to 200 °C, more preferably a range of 130 to 160 °C. Certain preferred embodiments of the method are provided, wherein the transition metal oxide is MnzCh, MnsC or combinations thereof, preferably MnzCh or MnsC , and wherein heating the transition metal oxide to a range of 200 to 400 °C, preferably a range of 220 to 300 °C, more preferably a range of 240 to 280 °C.

[0074] In preferred embodiments of the method the fluorine-containing gas is molecular fluorine (F2), hydrogen fluoride (HF), sulfur hexafluoride (SFe), nitrogen fluoride (NF3) or boron trifluoride (BF3); preferably molecular fluorine (F2).

[0075] In certain preferred embodiments of the method the fluorine-containing gas is substantially free of any non-fluorine-containing gas, such as oxygen or nitrogen. Preferably the fluorine-containing gas has a purity of at least 95 % (v / v), more preferably a purity of at least 98 % (v / v), most preferably a purity of at least 99% (v / v). As appreciated by the skilled the transition metal oxide is treated with the fluorine-containing gas consisting of molecular fluorine (F2), hydrogen fluoride (HF), sulfur hexafluoride (SFe), nitrogen fluoride (NF3) or boron trifluoride (BF3); preferably molecular fluorine (F2). Hence, the transition metal oxide is treated with a fluorine- containing gas comprising less than 5% (v / v) of the non-fluorine-containing gas, preferably less than 2% (v / v), more preferably less than 1% (v / v). An example of this non-fluorine containing gas can be oxygen, nitrogen or a combination thereof.

[0076] Preferred embodiments of the method are provided, wherein providing the transition metal oxide in a container. Preferred embodiments of the method are provided, wherein step i) comprises i-a) providing the transition metal oxide in the container, and i-b) placing the container under vacuum, preferably placing the container under a pressure of less than 100 mbar, preferably less than 75 mbar, more preferably less than 50 mbar.

[0077] Hence, in preferred embodiments of the method step iii) comprises treating the heated transition metal oxide with a fluorine-containing gas under vacuum, preferably placing the container under a pressure of less than 100 mbar, preferably less than 75 mbar, more preferably less than 50 mbar. As appreciated by the skilled any type of container suitable for heating and using fluorine-containing gases may be used. A suitable example is a nickel boat, preferably a nickel boat passivated with a NiFz layer.

[0078] In certain highly preferred embodiments the container is subjected to a passivation protocol before the steps for manufacturing the transition metal oxyfluoride, wherein the passivation protocol comprises putting the container, preferably a nickel boat, under vacuum, followed by injecting a first F-containing gas, preferably molecular fluorine, in the container to atmospheric pressure, followed by heating the container to 400 - 600 °C, preferably about 500 °C, followed by removing the first F-containing gas from the container and injecting a second F-containing gas at atmospheric pressure, preferably molecular fluorine, followed by cooling the container to room temperature, followed by removing the second F-containing and injection of an inert gas, preferably nitrogen, to an atmospheric pressure.

[0079] Preferred embodiments of the method are provided, wherein treating the heated transition metal oxide with the fluorine-containing gas of at least 5 minutes, preferably at least 30 minutes, more preferably at least 1 hour. Preferred embodiments of the method are provided, wherein treating the heated transition metal oxide with the fluorine-containing gas of at most 10 hours, preferably of at most 5 hours, more preferably of at most 3 hours. Preferred embodiments of the method are provided, wherein treating the heated transition metal oxide with the fluorine-containing gas between 5 minutes and 10 hours, preferably between 30 minutes and 5 hours, more preferably between 1 hour and 3 hours.

[0080] Preferred embodiments of the method are provided,

[0081] • wherein heating the transition metal oxide to a range of 110 to 1000 °C, preferably a range of 120 to 500 °C, more preferably a range of 125 to 300 °C; and

[0082] • wherein treating the heated transition metal oxide with the fluorine-containing gas between 5 minutes and 10 hours, preferably between 30 minutes and 5 hours, more preferably between 1 hour and 3 hours.

[0083] Certain preferred embodiments of the method are provided,

[0084] • wherein the transition metal oxide is MnO; • wherein heating the transition metal oxide to a range of 200 to 400 °C, preferably a range of 220 to 300 °C, more preferably a range of 240 to 280 °C; and

[0085] • wherein treating the heated transition metal oxide with the fluorine-containing gas between 5 minutes and 10 hours, preferably between 30 minutes and 5 hours, more preferably between 1 hour and 3 hours.

[0086] Certain preferred embodiments of the method are provided,

[0087] • wherein the transition metal oxide is MnzCh, MnsC or combinations thereof, preferably MnzCh or MnsC ;

[0088] • wherein heating the transition metal oxide to a range of 200 to 400 °C, preferably a range of 220 to 300 °C, more preferably a range of 240 to 280 °C; and

[0089] • wherein treating the heated transition metal oxide with the fluorine-containing gas between 5 minutes and 10 hours, preferably between 30 minutes and 5 hours, more preferably between 1 hour and 3 hours.

[0090] A highly preferred embodiment of the method is wherein the transition metal oxyfluoride compound is the transition metal oxyfluoride compound as defined in the first aspect of the invention. In this case all embodiments related to the transition metal oxyfluoride compound according to the first aspect of the invention apply mutatis mutandis to the method for manufacturing the transition metal oxyfluoride compound of the invention. For example, the various embodiments relating to the identity and amounts of formula (I), such as the values for x and y, are equally applicable to the method for manufacturing the transition metal oxyfluoride compound.

[0091] Product-by-process

[0092] In a third aspect the invention concerns the transition metal oxyfluoride compound obtainable by the method for manufacturing the transition metal oxyfluoride compound according to the second aspect of the invention. As appreciated by the skilled person all embodiments directed to the transition metal oxyfluoride compound according to the first aspect of the invention and / or the method according to the second aspect of the invention apply mutatis mutandis to the transition metal oxyfluoride compound obtainable by the method according to the invention. For example, the various embodiments relating to the identity and amounts of formula (I), such as the values for x and y, are equally applicable to the transition metal oxyfluoride compound obtainable by the method for manufacturing the transition metal oxyfluoride compound according to the second aspect of the invention.

[0093] EXAMPLES

[0094] Description of measurement methods and protocols

[0095] Passivation protocol of the nickel boat

[0096] A passivated nickel boat refers to a nickel boat which underwent a passivation protocol. The passivation protocol of a boat starts with the insertion of the boat into a reactor. The gas inlet valve and outlet valve are closed. A vacuum pump is turned on for 5 minutes to create a vacuum inside the reactor. The gas inlet is opened. Molecular fluorine (purity 98-99% v / v with HF max. 0.5% v / v and other gases, mainly Oz / Nz at about 0.5% v / v, Solvay Fluor) is then injected into the reactor at a constant rate of 40 mL.min'1until atmospheric pressure is reached. The gas inlet is closed and the gas outlet is opened. The reactor is next heated to 500 °C with a ramp of 5 °C. min-1. The gas inlet is opened and molecular fluorine is injected for an hour at a constant rate of 40 mL.min'1. The gas inlet and outlet are closed and the reactor naturally cools down to room temperature. The gas inlet is opened and nitrogen is injected at a constant rate of 400mL.min'1until atmospheric pressure is reached. The gas outlet is opened and nitrogen is injected at a constant rate of 200 mL.min'1for an hour and a half.

[0097] Dosage protocol

[0098] The sample was weighed before and after fluorination, the ratio "weight difference" over "initial weight" gives a weight uptake expressed in percentage of the initial weight. The fluorine amount in the sample was determined by dosage. The dosage protocol started with a microwave-assisted digestion step where about 10 mg of a sample was weighed, poured into a PTFE vessel with 20 mL of 20:80 acetic acid / water solution and then digested for 1 h at 190 °C with magnetic stirring in a microwave (Anton-Paar Multiwave 5000). The resulting solution was diluted ten times in water, then 10 mL of the diluted solution was added to 5 mL water and 10 mL of a sodium acetate solution with a pillow of TISAB powder (Total Ionic Strength Adjustment Buffer purchased by Hach). The final solution was dosed with a fluoride-specific electrode (Sension MM340), the measured fluoride concentration was converted to a fluorine mass which is divided by the weight of the sample to give a fluorine weight percentage.

[0099] XRD protocol

[0100] Powder X-ray diffraction (XRD) experiments were carried out on a Panalytical X-Pert Pro diffractometer equipped with a Cu Koi source and a linear X'celerator detector. The total counting time was 60 min and the angle step size was 0.033 ° in the 2- theta 10-70 ° range. The phase matching was performed using the Profex software and reference crystallographic files stemming from both the COD36 and ICSD37 databases.

[0101] Examples 1.1-1.3

[0102] The MnO precursor are placed on a passivated 15 cm long flat nickel boat. The boat is inserted into the reactor and the gas inlet and outlet are closed. A vacuum pump is turned on for 5 minutes to create vacuum (-960 mbar) inside the reactor. The reactor is heated to 140 °C with a ramp of 5 °C. min-1. The gas inlet is opened and molecular fluorine is injected at a constant rate of 10 mL.min-1(see Table 1 for the amounts for Ex 1.1-1.3). The gas inlet is closed and the reactor is then maintained at 140 °C for 30 minutes. The reactor naturally cools to room temperature. The gas inlet is opened and nitrogen is injected at a constant rate of 400 mL.min'1until atmospheric pressure is reached. The gas outlet is opened and nitrogen is injected at a constant rate of 200 mL.min'1for an hour and a half.

[0103] Table 1 : overview of amount of MnO and injected F amount

[0104] The pressure curves allow us to gain insights into the mole quantity of gases in the atmosphere of the reactor through the ideal gas law (pV = nRT with V = 1.2 xlO'3m3and R = 8.31). The numeric pressure values at different points of interest are presented in Table 2. • ph is the pressure after the heating step,

[0105] • ApN2 is the pressure step due to the inflow of nitrogen from the Swagelok tubes when the upstream valve is opened (this nitrogen is a leftover from the rinsing step of the previous fluorination experiment),

[0106] • peis the end pressure of the experiment when the reactor cooled to room temperature

[0107] Table 2: Numerical analysis resulting from the pressure curves

[0108] Table 3 presents numerical values of interest computed using the ideal gas law.

[0109] • Ap is the difference between the final pressure at room temperature Pe and the initial pressure at room temperature -0.960 bar (after the vacuum step).

[0110] • neis the quantity of mole in the gas phase corresponding to this pressure value

[0111] • nN2 is the quantity of mole of nitrogen computed at 140°C from Apn2

[0112] • mo is the mass of oxygen corresponding to the mole quantity ne-nN2

[0113] • mF is the mass of fluorine corresponding to the mole quantity ne-nN2.

[0114] Hence, in the case where some oxygen is released by the powder to the gas phase, this cannot be more than this value mo, which is around 1-2 wt.% relative to the amount of transition metal oxide (see Table 3). It can be concluded that the oxygen loss from the transition metal oxide is negligible when it undergoes fluorination. Likewise, the maximum amount of fluorine left in the gas phase is around 2 wt. %. We also conclude that the amount of fluorine left in the gas phase is negligible.

[0115] Table 3: mole and mass values resulting from the pressure analysis. The detailed values leading to the weight uptake in percentage and dosage values are presented in Table 4.

[0116] Table 4: the weight uptake and dosage MnO samples.

[0117] To compute a chemical formula for Examples 1.1-1.3, the manganese stoichiometry is set to 1 by convention for each compound (as in MnO) and then the stoichiometry of both 0 and F is computed:

[0118] MnO + x , -> MnO yvFz

[0119] The analysis of the pressure curves proves that the oxygen release from the manganese oxide is negligible. Therefore, the oxygen stoichiometry is also set to 1 in consistency with an insertion mechanism starting from MnO. In addition, the analysis of the pressure curves proves that no fluorine is left in the gas phase. The injected fluorine thus gives a first measurement of the amount of incorporated fluorine. Plus, as there is no oxygen loss, the weight uptake gives a second measurement of the amount of incorporated fluorine. As can be seen from Table 4, the weight uptakes coincide with the masses of injected F2. Finally, the dosage gives a third measurement of the amount of incorporated fluorine. As can be seen from Table 4, this dosed mass is higher than the fluorine mass actually injected into the reactor. As this over-estimation was reproducible for each sample, it is not due to a measurement uncertainty but considered to be an artifact of the dosage protocol. Therefore, the fluorine injected mass and the weight uptake are averaged into a fluorine stoichiometry. This corresponds to experimental formula of MnOFo.22, MnOFo.53 and MnOFo.so for Exl.l, Exl.2 and Exl.3 respectively. XR.D analysis shows that the manganese oxyfluorides of Examples 1.1-1.3 are amorphous. Examples 2.1-2.2

[0120] 1 to 3 g of the MnsC precursor are placed on a passivated 15 cm-long flat nickel boat. The boat is inserted into the reactor and the gas inlet and outlet are closed. A vacuum pump is turned on for 5 minutes to create vacuum inside the reactor. The reactor is heated to 260 °C with a ramp of 5°C.min'1. The gas inlet is opened and molecular fluorine is injected at a constant rate of 5 mL.min'1. The reactor is then maintained at 260 °C for two hours. The gas inlet is closed and the reactor naturally cools to room temperature. The gas inlet is opened and nitrogen is injected at a constant rate of 400 mL.min'1until atmospheric pressure is reached. The gas outlet is opened and nitrogen is injected at a constant rate of 200 mL.min'1for an hour and a half. Table 5 displays the amount of fluorine injected into the reactor, the weight uptake of the manganese oxide and the fluorine dosage as determined by the dosage protocol.

[0121] Table 5: amounts of fluorine injected into the reactor, the weight uptake of the manganese oxide and the fluorine dosage for Example 2.1 and Example 2.2.

[0122] The weight uptake closely relates to the fluorine dosage, but differs slightly from the amount of fluorine injected to the reactor. Therefore, the stoichiometry of the manganese oxyfluoride has to be calculated by the following formula with weight uptake ratio = "Am" in grams (= mass ratio of the manganese oxyfluoride over the manganese oxide) and fluorine dosage = "dos" in grams:

[0123] Chemical equation : MnO1 33+ F2-> MnOxFy

[0124] Applying above formula to Example 2.1 and 2.2 gives an experimental formula of MnOi.29Fo.5 and MnO1.27F0.92 respectively. Examples 3.1-3.3

[0125] 1 to 3 g of the MnzCh precursor are placed on a passivated 15 cm-long flat nickel boat. The boat is inserted into the reactor and the gas inlet and outlet closed. A vacuum pump is turned on for 5 minutes to create vacuum inside the reactor. The reactor is heated to 260 °C with a ramp of 5°C.min'1. The gas inlet is opened and molecular fluorine is injected at a constant rate of 5 mL.min'1. The reactor is then maintained at 260 °C for an hour. The gas inlet is closed and the reactor naturally cools to room temperature. The gas inlet is opened and nitrogen is injected at a constant rate of 400 mL.min'1until atmospheric pressure is reached. The gas outlet is opened and nitrogen is injected at a constant rate of 200 mL.min'1for 1.5 hours. Table 6 displays the amount of fluorine injected into the reactor, the weight uptake of the manganese oxide and the fluorine dosage as determined by the dosage protocol.

[0126] Table 6: amounts of fluorine injected into the reactor, the weight uptake of the manganese oxide and the fluorine dosage for Example 3.1 and Example 3.2.

[0127] The weight uptake closely relates to the fluorine dosage, but differs significantly form the amount of fluorine injected to the reactor. Therefore, the stoichiometry of the manganese oxyfluoride has to calculated by the following formula with weight uptake ratio = "Am" in grams (= mass ratio of the manganese oxyfluoride over the manganese oxide) and fluorine dosage = "dos" in grams:

[0128] Chemical equation : MnO1 5+ F2-> MnOxFy

[0129] Applying above formula to Example 3.1, Example 3.2 and Example 3.3 gives an experimental formula of MnO1.44F0.38, MnO1.37F0.97 and MnO1.15F1.34, respectively.

Claims

CLAIMS1. A transition metal oxyfluoride compound according to formula (I)MWy (I), wherein M1is selected from the group consisting of Mn, Ti, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations thereof, wherein 0 < x < 2, preferably 0.01 < x < 1.99; and wherein 0 < y < 2, preferably 0.01 < y < 1.99.

2. The transition metal oxyfluoride according to claim 1, wherein M1is Mn, Co, Ni or combinations thereof, preferably M1is Mn, Ni or Co, more preferably M1is Mn.

3. The transition metal oxyfluoride according to claim 1 or 2, wherein 0 < x < 1 or l < x < 2.

4. The transition metal oxyfluoride according to claim 3, wherein 0 < x < 1, preferably 0.1 < x < 0.9, more preferably 0.2 < x < 0.8.

5. The transition metal oxyfluoride according to claim 1 or 2, wherein 0 < y < l or l < y < 2.

6. The transition metal oxyfluoride according to any one of claims 5, wherein 0 < y < 1, preferably 0.1 < y < 0.9, more preferably 0.2 < y < 0.85.

7. The transition metal oxyfluoride according to claim 1 or 2, wherein 0.1 < x < 1.9, preferably 0.5 < x < 1.7, more preferably 1.0 < x < 1.5; and wherein 0.05 < y < 1.9, preferably 0.1 < y < 1.7, more preferably 0.2 < y < 1.4.

8. The transition metal oxyfluoride according to claim 3, wherein 1 < x < 2, preferably 1.1 < x < 1.9, more preferably 1.2 < x < 1.8.

9. The transition metal oxyfluoride according to claim 5, wherein 1 < y < 2, preferably 1.1 < y < 1.9, more preferably 1.2 < y < 1.85.

10. The transition metal oxyfluoride according to claim 1 or 2, wherein 0.5 < x < 1.9, preferably wherein 0.9 < x < 1.7, more preferably wherein 1.1 < x < 1.5; and wherein 0.1 < y < 1.9, preferably wherein 0.2 < y < 1.7, more preferably wherein 0.4 < y < 1.4.

11. A method for manufacturing a transition metal oxyfluoride compound, preferably the transition metal oxyfluoride compound according to any one of claims 1-10, comprising the following steps i) providing a transition metal oxide, ii) heating the transition metal oxide to at least 100 °C, and iii) treating the heated transition metal oxide with a fluorine-containing gas thereby affording a transition metal oxyfluoride compound, wherein the amount of fluorine present in the fluorine-containing gas for treating the heated transition metal oxide is defined as a ratio n(F) / n(M2) (mol / mol), wherein n(F) represents the amount of moles fluor present in the fluorine containing gas, and wherein n(M2) represents the amount of moles transition metal present in the transition metal oxide, wherein the ratio n(F) / n(M2) (mol / mol) is between 0.01 and 1.99.

12. Method according to claim 11, wherein the ratio n(F) / n(M2) (mol / mol) is between 0.01 and 0.99 or between 1.01 and 1.99, preferably between 0.1 and 0.95 or between 1.1 and 1.9, more preferably between 0.2 and 0.9 or between 1.2 and 1.5.

13. Method according to claim 11 or 12, wherein the ratio n(F) / n(M2) (mol / mol) is between 0.01 and 0.99, preferably between 0.1 and 0.9, more preferably between 0.2 and 0.8.

14. Method according to any one of claims 11-13, wherein treating the heated transition metal oxide with a fluorine-containing gas under vacuum, preferably under a pressure of less than 100 mbar, preferably less than 75 mbar, more preferably less than 50 mbar.

15. Method according to any one of claims 11-14, wherein the transition metal oxide is according to formula (II)M2aOb (II) wherein M2is selected from the group consisting of Mn, Ti, Co, V, Cr, Ni, Zr, Nb, Mo, Sn, Sb, Al and combinations thereof; wherein 0 < a < 4, preferably 0 < a < 3; and wherein 0 < b < 5, preferably 0 < b < 4.

16. Method according to any one of claims 11-15, wherein the fluorine-containing gas is molecular fluorine (F2), hydrogen fluoride (HF), sulfur hexafluoride (SFe), nitrogen fluoride (NF3) or boron trifluoride (BF3); preferably molecular fluorine

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