Thermoanalytic determination of alkali metals and / or alkaline earth metals and / or related metals

Abstract

The present invention relates to a method for thermoanalytically determining alkali metals and / or alkaline earth metals and / or related metals.

Description

[0001] Thermoanalytical determination of alkali and / or

[0002] alkaline earth metals and / or related metals

[0003] Field of the invention

[0004] The invention relates to a method for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals. The invention further relates to the use of gold for the thermoanalytical measurement of a sample comprising at least one alkali and / or alkaline earth metal and / or related metal.

[0005] State of the art

[0006] The development of analytical methods for investigating the properties of substances and for determining and quantifying components of a composition has long been of great importance in industry and research. Depending on the analytical method, however, the sample to be analyzed often requires complex preparation to obtain representative measurement results. Furthermore, information is often only obtained about a part of the sample, such as its surface. Therefore, there is a need to develop simple and straightforward analytical methods that provide the highest possible information content about the sample under investigation.

[0007] The determination of alkali metals, in particular, is of great importance in battery technology. For example, wet-chemical methods for determining lithium in battery materials are known in the state of the art. The sample to be analyzed, usually a solid, must first be quantitatively dissolved using a suitable digestion method (e.g., acid digestion). Insoluble components are filtered off. The resulting analysis solution is measured using spectroscopic methods (e.g., atomic absorption spectroscopy) against a standard solution with a known analyte content. The analyte concentration is determined by comparing the intensity of the measurement of the analysis solution with the intensity of the measurement of the standard solution. This procedure makes it possible to determine the total content of an analyte in a solid. However, these methods have the disadvantage of complex sample preparation.

[0008] Another method for determining lithium is solid-state Li NMR. The solid can be measured directly as a solid, if necessary, without dissolution after complex sample preparation in a rotator. However, the nuclear magnetic resonance (NMR) method is often complicated or limited by the presence of other nuclei with a large quadrupole moment. This particularly applies to the 3d series of transition metals relevant for electrode materials.

[0009] Furthermore, common spectroscopic methods for determining alkali metals on solids are known. For example, energy-dispersive X-ray spectroscopy provides local information on the alkali metal content. However, determining the total alkali metal content in the sample requires a homogeneous distribution of the analyte throughout the sample. Furthermore, multiple analyses of local alkali metal concentrations are often necessary.

[0010] Accordingly, there is a need to develop methods for the determination of alkali and / or alkaline earth metals that are simple, uncomplicated, and quick to perform. Furthermore, there is a need for methods for the determination of alkali and / or alkaline earth metals that allow the determination of the entire volume of a sample, not just on its surface. Furthermore, there is a need to develop simple, uncomplicated, and quick methods for determining the alkali and / or alkaline earth metal content of a sample. There is also a need to develop methods for the determination of alkali and / or alkaline earth metals in electrode materials and / or the content of alkali and / or alkaline earth metals in electrode materials. Finally, there is a need for a method that can determine the state of charge (SOC) of a battery electrode.

[0011] Summary of the Invention In a first aspect, the present invention provides a method for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals, the method comprising providing a sample comprising at least one alkali and / or alkaline earth metal and / or related metal and performing a thermoanalytical measurement of the sample. During the thermoanalytical measurement, the sample is in contact with gold, and the sample is substantially free of solvents.

[0012] The method according to the invention enables a simple, uncomplicated, and rapid determination of alkali and / or alkaline earth metals and / or related metals in samples comprising at least one alkali and / or alkaline earth metal and / or related metal. Complex sample preparation as required with wet-chemical methods is avoided. In contrast to methods that only allow the examination of a part of a sample, such as the surface, the sample can be analyzed with regard to its entire volume using the method according to the invention. Furthermore, the method according to the invention enables a simple, uncomplicated, and rapid determination of the content of at least one alkali and / or alkaline earth metal and / or related metal in a sample.Furthermore, the method according to the invention enables the determination of alkali and / or alkaline earth metals and / or related metals in electrodes and / or electrode materials and / or the content of alkali and / or alkaline earth metals and / or related metals in electrodes and / or electrode materials. This enables, in particular, the simple and uncomplicated determination of the charge state of a battery electrode. Compared to prior art methods, such as NMR, the method involves lower investment costs. Furthermore, the technical complexity of the method according to the invention is low, which means that its implementation requires a lower level of experience.

[0013] In a further aspect, the present invention provides a use of gold for the thermoanalytical measurement or determination of alkali and / or alkaline earth metals and / or related metals in a sample comprising at least one alkali and / or alkaline earth metal and / or related metal. The sample is essentially free of solvents and is in contact with the gold during the thermoanalytical measurement.

[0014] The use according to the invention enables a simple, uncomplicated, and rapid determination of alkali and / or alkaline earth metals and / or related metals in samples comprising at least one alkali and / or alkaline earth metal and / or related metal. The above advantages of the method according to the invention apply analogously to the use according to the invention.

[0015] Further aspects of the present invention can be found in the dependent claims and the detailed description.

[0016] Figures

[0017] The accompanying drawings are intended to illustrate embodiments of the present invention and to provide a further understanding thereof. Together with the description, they serve to explain concepts and principles of the invention. Other embodiments and many of the noted advantages will become apparent upon review of the drawings. The elements of the drawings are not necessarily drawn to scale. Identical, functionally equivalent, and acting elements, features, and components are designated by the same reference numerals throughout the figures of the drawings, unless otherwise noted.

[0018] Fig. 1 : Schematic representation of a method according to the invention for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals, wherein the method comprises providing a sample comprising at least one alkali and / or alkaline earth metal and / or related metal 1 and carrying out a thermoanalytical measurement of the sample 2.

[0019] Fig. 2: Representation of DSC measurements of lithium-containing samples. The dashed line represents a measurement signal from an exemplary method according to the invention, in which a lithium foil was measured in a stainless steel crucible with a gold coating. The dashed-dotted line represents a measurement signal from an exemplary method according to the invention, in which a lithium foil was measured together with a gold foil in a stainless steel crucible. The solid line represents a measurement signal from a DSC measurement of a lithium foil in a stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals.

[0020] Fig. 3: Representation of DSC measurements of dried and undried lithium-containing samples. The dashed line represents a measurement signal from a DSC measurement, in which a non-dried lithium manganate sample was measured in a gold-coated stainless steel crucible. The solid line represents a measurement signal from an exemplary method according to the invention, in which a dried lithium manganate sample was measured in a gold-coated stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals.

[0021] Fig. 4: Representation of DSC measurements of sodium-containing samples. The dashed line represents a measurement signal from an exemplary method according to the invention, in which a dried sodium-containing sample was measured in a gold-coated stainless steel crucible. The solid line represents a measurement signal from a DSC measurement of a dried sodium-containing sample in a stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals.

[0022] Fig. 5: Representation of DSC measurements of potassium-containing samples. The dashed line represents a measurement signal from an exemplary method according to the invention, in which a dried potassium-containing sample was measured in a gold-coated stainless steel crucible. The solid line represents a measurement signal from a DSC measurement of a dried potassium-containing sample in a stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals.

[0023] Fig. 6: Representation of a measurement signal of an exemplary method according to the invention, wherein a dried calcium-containing sample was measured in a stainless steel crucible with a gold coating. The hatched area below the line represents the integral of the exothermic signal. Fig. 7: Top: Representation of a DSC measurement with an isothermal heating segment of a lithium-containing sample. The dashed line represents a measurement signal of an exemplary method according to the invention, wherein a lithium foil was measured in a stainless steel crucible with a gold coating using an isothermal heating segment. The solid line represents a measurement signal of a DSC measurement with an isothermal heating segment of a stainless steel crucible without a sample as a reference. The hatched areas below the lines represent the integrals of the exothermic signals and the reference, respectively. Below: Representation of the temperature change program used in the DSC measurement.

[0024] Fig. 8: Representation of DSC measurements of lithium manganate as cathode material with SOC 100. The dashed line represents a measurement signal from an exemplary method according to the invention, in which dried lithium manganate was measured with SOC 100 in a gold-coated stainless steel crucible. The solid line represents a measurement signal from a DSC measurement of dried lithium manganate with SOC 100 in a stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals.

[0025] Fig. 9: Representation of DSC measurements of lithium manganate as cathode material with SOC 100 and SOC 50. The dashed line represents a measurement signal from an exemplary method according to the invention, in which dried lithium manganate was measured with SOC 100 in a stainless steel crucible with gold coating. The solid line represents a measurement signal from an exemplary method according to the invention, in which dried lithium manganate was measured with SOC 50 in a stainless steel crucible with gold coating. The hatched areas below the lines represent the integrals of the exothermic signals.

[0026] Fig. 10: Representation of DSC measurements of lithium cobaltate as cathode material with SOC 100. The dashed line represents a measurement signal of an exemplary method according to the invention, wherein dried lithium cobaltate was measured with SOC 100 in a stainless steel crucible with gold coating. The solid line represents a measurement signal of a DSC measurement of dried lithium cobaltate with SOC 100 in a stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals. Fig. 11: Representation of DSC measurements of lithium cobaltate as cathode material with SOC 100 and SOC 0. The dashed line represents a measurement signal of an exemplary method according to the invention, wherein dried lithium cobaltate was measured with SOC 100 in a stainless steel crucible with gold coating.The solid line represents a measurement signal from an exemplary method according to the invention, in which dried lithium cobaltate was measured with SOCl 0 in a gold-coated stainless steel crucible. The hatched areas below the lines represent the integrals of the exothermic signals.

[0027] Fig. 12: Representation of DSC measurements of elemental lithium at a heating rate of 3 K / min. The dashed line represents a measurement signal from an exemplary method according to the invention, in which a lithium foil was measured in a stainless steel crucible with a gold coating. The solid line represents a measurement signal from an exemplary method according to the invention, in which a lithium foil was measured in a stainless steel crucible without a gold coating. The hatched areas below the lines represent the integrals of the exothermic signals.

[0028] Fig. 13: Representation of DSC measurements of elemental lithium at a heating rate of 30 K / min. The dashed line represents a measurement signal from an exemplary method according to the invention, in which a lithium foil was measured in a stainless steel crucible with a gold coating. The solid line represents a measurement signal from an exemplary method according to the invention, in which a lithium foil was measured in a stainless steel crucible without a gold coating. The hatched areas below the lines represent the integrals of the exothermic signals.

[0029] Detailed description of the invention

[0030] Definitions

[0031] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Amounts used in this invention are in weight percent unless otherwise specified or apparent from the context.

[0032] A related metal is not particularly limited within the scope of the invention. A related metal is one that is similar in its properties to an alkali and / or alkaline earth metal, for example, with regard to its valence, so that monovalent and divalent metals such as silver or copper are particularly included as monovalent metals, and most heavy metals such as copper, zinc, or cadmium are included as divalent metals.

[0033] The term "thermoanalytical measurement" is not particularly limited within the scope of the present invention, except that, within the scope of the present invention, exclusively gravimetric methods are not encompassed by the term "thermoanalytical measurement." Accordingly, the term "thermoanalytical measurement" within the scope of the present invention does not encompass thermogravimetry per se, but does encompass, for example, STA (simultaneous thermal analysis). Within the scope of the present invention, the terms "thermoanalytical measurement" and "thermal analysis" can be used synonymously. As is generally known, a thermoanalytical measurement examines the physical and chemical properties of a sample, which change with temperature.In a thermoanalytical measurement, the physical and / or chemical properties of a sample are measured as a function of temperature while the substance is subjected to a temperature change program. This means that in a thermoanalytical measurement, a sample is exposed to an excitation that produces an observable response. The response signal corresponding to this observable response is measured using measuring equipment. The data comprising the response signal and the excitation as a function of time is used to calculate a thermoanalytical measurement curve that enables the identification of the thermal effect. In some embodiments, the thermoanalytical measurement is selected from the group consisting of DSC (Differential Scanning Calorimetry), ARC (Accelerating Rate Calorimetry), MMC (Multi-Module Calorimetry), DTA (Differential Thermal Analysis), STA (Simultaneous Thermal Analysis), and combinations thereof.The term "calorimetry" is not particularly limited within the scope of the present invention. As is generally known, calorimetry refers to the measurement of heat quantities that are linked to biological, chemical, or physical processes and can be both exothermic and endothermic. A calorimeter is used for the determination.

[0034] The term "differential scanning calorimetry" is not particularly limited within the scope of the present invention. As is generally known, differential scanning calorimetry (DSC) measures the amount of heat released or absorbed by a sample during heating, cooling, or an isothermal process. In DSC, a first measuring container containing a sample and a second measuring container empty are subjected to the same temperature change program. The first and second measuring containers are identical. The second measuring container empty is referred to as the reference. Due to the heat capacity of the sample and exothermic or endothermic processes and / or phase changes such as melting or evaporation, temperature differences arise between the sample and the reference, as thermal energy flows into or out of the sample during the process under investigation.

[0035] The term "sample" is not particularly limited within the scope of the present invention, except that the sample contains at least one alkali metal and / or at least one alkaline earth metal and / or at least one related metal. The terms "sample" and "analysis sample" can be used synonymously. As is generally known, a sample refers to the entirety of a material to be analyzed. The sample can be a solid, liquid, or waxy sample under normal conditions. In particular, the sample can be a solid sample under normal conditions.

[0036] In the context of the present invention, the term "normal conditions" refers to a temperature of 20 °C and a pressure of 1.013 bar. The terms "normal conditions", "standard conditions", and "laboratory conditions" can be used synonymously.

[0037] The term "electrode" is not particularly limited within the scope of the present invention.

[0038] As is generally known, an electrode is an electron conductor that interacts with a counter electrode (anode-cathode) and a medium located between the two electrodes. Within the scope of the present invention, the electrode can be a cathode and / or an anode. In some embodiments, the electrode is an electrode of a battery, for example, a lithium battery, sodium battery, alkaline-manganese battery, tin-based battery, sulfur-based battery, zinc-based battery, polymer-based battery, etc., but is not limited thereto. A battery here includes, in particular, primary and secondary batteries and is not particularly limited.

[0039] The term "solvent" is not particularly limited within the scope of the present invention. As is generally known, a solvent refers to a substance that can dissolve and dilute gases, liquids, or solids without chemical reactions occurring between the solvent, the substance to be dissolved, and the dissolved substance during the dissolution process. Liquids such as water and / or liquid inorganic and / or organic substances, as well as mixtures thereof, optionally with suitable and unlimited additives, are generally used as solvents. Within the scope of the present invention, a solvent is liquid under normal conditions. A suitable solvent is, in particular, a solvent that does not falsify the analysis by removing the at least one alkali and / or alkaline earth metal and / or related metal from the analysis. Suitable solvents are known to an analytical chemist.

[0040] The term "essentially solvent-free" is not particularly limited within the scope of the present invention. A sample is essentially solvent-free if the solvent content in the sample is less than 0.5 wt.%, preferably less than 0.1 wt.% and particularly preferably less than 0.01 wt.%, based on the total weight of the sample. Alternatively or additionally, a sample is essentially solvent-free if the solvent content in the sample has an inherent vapor pressure of at most 10' 1 mbar, preferably maximum 10' 2 mbar and particularly preferably a maximum of 10' 3mbar. The inherent vapor pressure can be measured, for example, using a suitable pressure measuring device, for example on a Schlenk line or on a sample container. In the context of the present invention, the term "reference" refers to a second measuring container without contents, wherein the first measuring container contains the sample to be measured and the first and second measuring containers are identical. "Identical" means that the measuring containers have the same properties and, in particular, the same structure, the same material, the same dimensions, and the same weight.

[0041] The term "essentially inert" is not particularly limited within the scope of the present invention. In some embodiments, an atmosphere is essentially inert if the atmosphere has a water content of at most 10 ppm, preferably at most 5 ppm, and particularly preferably at most 1 ppm, and an oxygen content of at most 10 ppm, preferably at most 5 ppm, and particularly preferably at most 1 ppm.

[0042] A first aspect of the invention relates to methods for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals, wherein the method comprises providing a sample comprising at least one alkali and / or alkaline earth metal and / or related metal and performing a thermoanalytical measurement of the sample. The sample is essentially solvent-free and is in contact with gold during the thermoanalytical measurement.

[0043] According to the invention, a sample comprising at least one alkali metal, i.e. one alkali metal or two or more alkali metals, a sample comprising at least one alkaline earth metal, i.e. one alkaline earth metal or two or more alkaline earth metals, a sample comprising at least one related metal, i.e. one related metal or two or more related metals, or a sample comprising mixtures thereof, i.e. at least one alkali and at least one alkaline earth metal, at least one alkali metal and at least one related metal, at least one alkaline earth metal and at least one related metal, or at least one alkali, at least one alkaline earth metal and at least one related metal. According to certain embodiments, the sample comprises at least one alkali metal, i.e. one alkali metal or two or more alkali metals.According to certain embodiments, the sample comprises at least one alkaline earth metal, i.e., one alkaline earth metal or two or more alkaline earth metals. According to certain embodiments, the sample comprises at least one related metal, i.e., one related metal or two or more related metals. According to certain embodiments, the sample comprises at least one alkali and at least one alkaline earth metal. According to certain embodiments, the sample comprises at least one alkali metal and at least one related metal. According to certain embodiments, the sample comprises at least one alkali, at least one alkaline earth metal, and at least one related metal. According to certain embodiments, the sample comprises at least one alkali, at least one alkaline earth metal, and at least one related metal.

[0044] The inventors have surprisingly discovered that measurement signals from a sample comprising at least one alkali and / or alkaline earth metal and / or related metal can be generated in a thermoanalytical measurement of this sample when the sample is in contact with gold. Without wishing to be bound to a particular theory, it is assumed that an exothermic reaction between the gold and the alkali and / or alkaline earth metal and / or related metal takes place during the thermoanalytical measurement, which can be measured and evaluated as a measurement signal. This measurement signal can be used to obtain qualitative and / or quantitative information about the sample. Furthermore, the inventors have discovered that the presence of solvents interferes with the determination and distorts the measurement signal. The evaluation of measurement signals from thermoanalytical measurements is well known to those skilled in the art.

[0045] Without wishing to be bound to any particular theory, it is further assumed that the reaction between the gold and the alkali and / or alkaline earth metal and / or related metal forms an alloy and / or a solid solution and / or an intermetallic compound.

[0046] "Being in contact" means that at least a portion of the sample and at least a portion of the gold are touching and / or at least a portion of the sample and at least a portion of the gold have a contact surface. According to some embodiments, the sample and the gold are in contact such that the sample and / or the alkali and / or alkaline earth metal and / or related metal of the sample can react with the gold.

[0047] Conducting the thermoanalytical measurement may involve the use of commercially available analytical instruments, such as calorimeters. Such analytical instruments are commercially available and should preferably be operated according to the respective manufacturer's instructions.

[0048] The sample contains at least one alkali metal and / or at least one alkaline earth metal and / or at least one related metal. The alkali metal can be selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr), as well as mixtures thereof. The alkaline earth metal can be selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), as well as mixtures thereof. The related metal can in particular be selected from other monovalent and divalent metals such as silver (Ag), copper (Cu), zinc (Zn), cadmium (Cd), and mixtures thereof. In preferred embodiments, the related metal is selected from the group consisting of silver (Ag), tin (Sn), indium (In), zinc (Zn), copper (Cu), and cadmium (Cd). In some embodiments, the alkali metal is selected from the group consisting of lithium, sodium, potassium, and cesium.According to certain embodiments, the alkali metal is selected from the group consisting of lithium, potassium, and cesium. In some embodiments, the alkali metal is lithium. According to some embodiments, the alkaline earth metal is selected from the group consisting of beryllium, magnesium, calcium, strontium, and barium. In certain embodiments, the alkaline earth metal is selected from the group consisting of magnesium and calcium. In some embodiments, the alkaline earth metal is calcium. According to some embodiments, the sample contains at least one alkali metal. In certain embodiments, the sample contains lithium. According to some embodiments, the method is a method for the thermoanalytical determination of lithium.

[0049] In some embodiments, the method is a method for the thermoanalytical determination of the content of at least one alkali metal and / or an alkaline earth metal and / or a related metal in a sample. In some embodiments, the method is a method for the thermoanalytical determination of the lithium content of a sample, in particular of an electrode material. According to certain embodiments, the method is a method for the calorimetric determination of the lithium content of a sample, in particular of an electrode material. In some embodiments, the sample is dried before performing the thermoanalytical measurement. The drying of the sample is not particularly limited. According to some embodiments, a drying device is used to dry the sample. A suitable drying device can be an oven such as a muffle furnace and / or a drying cabinet.Alternatively or additionally, the sample can also be dried in situ as part of the measurement process in the measuring device, for example by running a heating program to dry the sample. Alternatively or additionally, the sample can be dried under vacuum. Suitable devices for drying under vacuum include a vacuum dryer, a rotary evaporator and / or a Schlenk line with a vacuum pump. By drying the sample, it can be ensured that the sample is essentially free of solvents. The drying of the sample can be carried out in such a way that the sample is solvent-free after drying. Drying the sample before the thermoanalytical measurement is advantageous because the sample does not have to be provided essentially solvent-free straight away, thus making sample selection more flexible.

[0050] In a method according to the invention, it is also possible for the sample to be prepared under an inert gas, as described further below. Inert gas here means that a reaction between the inert gas and the sample can be ruled out under the operating conditions, so that the inert gas can also be determined depending on the at least one alkali metal and / or alkaline earth metal and / or related metal to be analyzed. For example, nitrogen can lead to the formation of lithium nitride when using lithium, so argon, for example, may be the preferred inert gas for lithium determination.

[0051] In certain embodiments, during the thermoanalytical measurement, at least a portion of the at least one alkali and / or alkaline earth metal and / or related metal in the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is allowed to react with at least a portion of the gold. "Reacting" means that the measurement conditions of the thermoanalytical measurement are adjusted such that a reaction occurs between at least a portion of the at least one alkali and / or alkaline earth metal and / or related metal and at least a portion of the gold. The choice of measurement conditions depends on the properties of the sample and on the alkali and / or alkaline earth metal and / or related metal. Based on the measurement signal generated by the thermoanalytical measurement, it can be determined in which temperature range the reaction of the alkali and / or alkaline earth metal and / or related metal with the gold takes place.

[0052] According to some embodiments, the thermoanalytical measurement is a calorimetry and / or a calorimetric measurement. Alternatively or additionally, the thermoanalytical measurement may be a differential scanning calorimetry (DTA). In certain embodiments, the thermoanalytical measurement is selected from the group consisting of DSC (Differential Scanning Calorimetry), ARC (Accelerating Rate Calorimetry), MMC (Multi-Module Calorimetry), DTA (Differential Thermal Analysis), STA (Simultaneous Thermal Analysis), and combinations thereof. According to some embodiments, the thermoanalytical measurement is selected from the group consisting of DSC, ARC, MMC, and STA. In certain embodiments, the thermoanalytical measurement is a dynamic differential scanning calorimetry (DSC).

[0053] According to certain embodiments, the thermoanalytical measurement can comprise the implementation of a temperature change program. The temperature change program can comprise a dynamic heating rate and / or an isothermal heating segment. In some embodiments, the temperature change program comprises heating the sample and optionally a reference from a first temperature to a second temperature using a heating rate. The determination of the first temperature, the second temperature and the heating rate depends on the type and properties of the sample to be examined and of the alkali and / or alkaline earth metal and / or related metal. To determine suitable temperatures and heating rates, for example, a method according to the invention can first be carried out, wherein the sample and optionally the reference are heated using a temperature change program with a high heating rate (e.g. 30 K / min), e.g.from 10°C or from room temperature (22°C) to 1600°C, for example, up to 1000°C. Based on the measurement signals, the temperature range in which the reaction between the alkali and / or alkaline earth metals and / or related metals and the gold takes place can then be estimated. The measurement parameters of the

[0054] Temperature change program can be finely adjusted. In some embodiments, the first temperature is -10 °C to 150 °C, preferably 0 °C to 100 °C and particularly preferably 20 °C to 40 °C or 0 °C to 20 °C, the latter for example when Cs is determined. According to certain embodiments, the second temperature is at least 300 °C, preferably at least 400 °C and particularly preferably at least 500 °C. According to some embodiments, the second temperature is a maximum of 1600 °C, preferably a maximum of 1200 °C and particularly preferably a maximum of 1000 °C. For some samples, a lower second temperature of a maximum of 900 °C, a maximum of 800 °C, a maximum of 700 °C, a maximum of 600 °C or a maximum of 500 °C may also be suitable, for example when determining Li. The heating rate can be, for example, 3 to 30 K / min.

[0055] Alternatively or additionally, the temperature change program can comprise holding the sample (isothermal) and optionally a reference at a temperature for a holding time. As already explained above, the determination of the temperature and holding time depends on the type and properties of the sample to be examined and the alkali and / or alkaline earth metal. The determination can be made through suitable preliminary tests as described above. In some embodiments, the temperature is at least 20°C, for example at least 25°C, preferably more than 25°C. A low temperature is advantageous, for example, if cesium is to be determined. For other elements such as lithium, higher temperatures are advantageous, e.g. 200°C to 240°C. In some embodiments, the temperature is 20°C to 1000°C. Alternatively or additionally, the holding time can be at least 15 min (minutes), for example at least 0.5 hours (h).In some embodiments, the holding time is 15 minutes to 12 hours, for example 0.5 to 10 hours, preferably 1 to 8 hours, and particularly preferably 1.5 to 5 hours.

[0056] According to some embodiments, an inert gas stream is set up to carry out the thermoanalytical measurement. The inert gas stream is passed over and / or through the sample during the thermoanalytical measurement. The inert gas of the inert gas stream can be helium (He), argon (Ar), and / or nitrogen (N2) and can be suitably selected based on the analyte. In some embodiments, the flow rate of the inert gas stream is 5 to 150 mL / min, preferably 10 to 100 mL / min, and particularly preferably 15 to 80 mL / min. In certain embodiments, the gold is present in excess relative to the at least one alkali and / or alkaline earth metal and / or related metal. An excess refers to the molar ratio. This is particularly advantageous if a quantitative or partially quantitative determination of the content of the at least one alkali and / or alkaline earth metal and / or related metal in the sample is to be carried out.Whether an excess is present can be determined by means of suitable preliminary considerations and / or simple preliminary tests. The excess refers to the molar ratio. Alternatively or additionally, the weight ratio of the sample to gold can be 1:>1. This further improves the determination of the content of the at least one alkali and / or alkaline earth metal and / or related metal in the sample. In some embodiments, the weight ratio of the sample to gold is 1:1 to 1:100. According to some embodiments, the content of the at least one alkali and / or alkaline earth metal and / or related metal in the sample is a maximum of 10 wt.%, preferably a maximum of 3 wt.%, and particularly preferably a maximum of 1 wt.%.

[0057] According to some embodiments, the sample is filled into a measuring container prior to the thermoanalytical measurement, and the measurement is carried out with the sample in the measuring container. The measuring container is not particularly limited, except that the measuring container must be suitable for a thermoanalytical measurement. In some embodiments, the sample is filled into a first measuring container prior to the thermoanalytical measurement, and the measurement is carried out with the sample in the first measuring container and with a second measuring container without contents. The first and second measuring containers are identical. The second measuring container is referred to as the reference. Alternatively or additionally, the sample can be weighed into the measuring container. In some embodiments, the sample amount is 0.5 to 150 mg, preferably 1 to 100 mg, and particularly preferably 5 to 20 mg.

[0058] In some embodiments, the measuring container comprises the gold. According to certain embodiments, the first measuring container comprises the gold. The gold can be present as gold foil and / or gold powder. For example, the gold can be placed in the measuring container, and the sample can then be poured and / or weighed into the measuring container. Alternatively or additionally, the sample can be mixed and / or blended with gold before being poured into the measuring container, and the sample can be poured into the measuring container with the gold. The gold can be present as gold foil and / or gold powder. Alternatively or additionally, the measuring container can be gold-plated and / or coated with gold, or even made of gold. "Gold-plated" here means that at least part of the measuring container is made of gold. The gold is arranged such that it can be in contact with the sample. According to the invention, it is also not excluded that the measuring container is made of gold.In particular with a purity as is commercially available, e.g. 99.90 or 99.95%.

[0059] According to certain embodiments, the measuring container is a crucible. In some embodiments, the measuring container is a high-pressure container and / or a high-pressure crucible. However, the measuring container does not have to be a high-pressure container.

[0060] In some embodiments, the measuring container for conducting the thermoanalytical measurement is hermetically sealed. This is advantageous when the thermoanalytical measurement and / or the method is carried out under inert conditions and / or a substantially inert atmosphere. "Inert conditions" refers to conditions that largely exclude contact of the sample with water and oxygen, i.e., water and oxygen are present at a maximum within the limits specified above.

[0061] In certain embodiments, the preparation of the sample, the drying of the sample, the filling of the sample into the measuring container, and / or the conduction of the thermoanalytical measurement are carried out under inert conditions and / or in a substantially inert atmosphere. This is advantageous if the sample is air- and / or water-sensitive.

[0062] In some embodiments, the thermoanalytical measurement comprises performing one or more thermoanalytical calibration measurements. The thermoanalytical calibration measurements are also performed with calibration samples that are essentially free of solvents.

[0063] In some embodiments, the thermoanalytical measurement comprises performing a thermoanalytical calibration measurement. The thermoanalytical calibration measurement is performed using a calibration sample with a known content of at least one alkali and / or alkaline earth metal and / or related metal. The thermoanalytical measurement of the sample and the thermoanalytical calibration measurement of the calibration sample are performed under the same measurement conditions. By comparing the measurement signals of the thermoanalytical calibration measurement and the thermoanalytical measurement, the content of the at least one alkali and / or alkaline earth metal and / or related metal in the sample can be determined. The evaluation can be performed by integrating the measurement signals over a temperature range. The temperature range depends on the type and properties of the sample and of the at least one alkali and / or alkaline earth metal and / or related metal.The temperature range is determined in particular by the heat of reaction between the at least one alkali and / or alkaline earth metal and / or related metal and the gold. For example, the content of the at least one alkali and / or alkaline earth metal and / or related metal can be determined from the ratio of the integral values ​​obtained by integrating the measurement signals.

[0064] In some embodiments, a first and a second thermoanalytical calibration measurement are carried out. The first and the second thermoanalytical calibration measurements are carried out under the same measurement conditions. In the first thermoanalytical calibration measurement, the calibration sample is in contact with gold, and in the second thermoanalytical calibration measurement, the calibration sample is not in contact with gold. For example, for the first thermoanalytical calibration measurement, the calibration sample is mixed with gold, and the mixture of calibration sample and gold is measured. In the second thermoanalytical calibration measurement, only the calibration sample is measured. From the comparison of the measurement signals of the first and second thermoanalytical calibration measurements, the heat of reaction of the reaction between the at least one alkali and / or alkaline earth metal and / or related metal and the gold can be determined.This heat of reaction can then be used as a reference value for determining the content of at least one alkali and / or alkaline earth metal and / or related metal in a sample. The measurement signals of the first and second thermoanalytical calibration measurements can, for example, be integrated over a temperature range, and the resulting integral values ​​can be subtracted from one another to obtain the reference value. In particular, the reference value can be determined by subtracting the integral value of the measurement signal of the second thermoanalytical calibration measurement from the integral value of the measurement signal of the first thermoanalytical calibration measurement.

[0065] In some embodiments, performing the thermoanalytical measurement of the sample comprises evaluating a measurement signal obtained by the thermoanalytical measurement. The evaluation can be performed by integrating the measurement signals over a temperature range. The temperature range depends on the type and properties of the sample and the at least one alkali and / or alkaline earth metal and / or related metal. An integral value can be obtained from the integration of the measurement signal. The content of the at least one alkali and / or alkaline earth metal and / or related metal in the sample can be determined from the ratio of the integral value to a reference value. The reference value can either be determined as described above or is already known and / or stored in a device for evaluating the thermoanalytical measurement.

[0066] According to some embodiments, the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is at least a part of an electrode. Alternatively or additionally, the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is at least a part of an electrode material. According to some embodiments, the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is an electrode. Alternatively or additionally, the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is an electrode material. In some embodiments, the electrode is an electrode of a battery. According to certain embodiments, the electrode material is an electrode material of a battery. In some embodiments, the sample is an alkali metal-containing electrode material.According to some embodiments, the sample is an alkali metal-containing sample, wherein the sample is an electrode material. The alkali metal can preferably be selected from the group consisting of lithium, sodium, and optionally cesium. In some embodiments, the electrode material is a cathode material. According to certain embodiments, the electrode material contains at least one transition metal, which is not particularly limited. However, the electrode material is not limited thereto and includes those contained in conventional batteries as defined above. In some embodiments, the electrode material contains multiple transition metals.

[0067] In certain embodiments, the sample is an electrode material, wherein providing the sample comprises removing electrode material from a battery and washing the electrode material. Washing can be performed with a suitable solvent—as exemplified above—which is not limited and can be specifically adapted to the electrode material. Subsequently, the electrode material is preferably dried by drying the sample as described above.

[0068] According to some embodiments, the method comprises determining the state of charge (SOC) of the electrode and / or the electrode material. The method can then be directed to determining the content of the at least one alkali metal and / or alkaline earth metal and / or related metal, for example the alkali metal content and in particular the lithium content, of the sample. The state of charge of the electrode and / or the electrode material can be deduced from the content of the at least one alkali metal and / or alkaline earth metal and / or related metal, for example the alkali metal content. The content of the at least one alkali metal and / or alkaline earth metal and / or related metal, for example the alkali metal content, can be determined using the thermoanalytical calibration measurements described above and / or using a reference value as described above.In certain embodiments, the sample may be an electrode material of a lithium battery and the calibration sample may be a lithium foil.

[0069] An exemplary method according to the invention for the thermoanalytical determination of alkali and / or alkaline earth metals is shown schematically in Figure 1, wherein the method comprises providing a sample 1 containing alkali and / or alkaline earth metals and carrying out a thermoanalytical measurement of the sample 2. A second aspect of the present invention relates to a use of gold for the thermoanalytical measurement or determination of a sample comprising at least one alkali and / or alkaline earth metal and / or related metal, wherein the sample is substantially free of solvents, and wherein the sample is in contact with the gold during the thermoanalytical measurement.In some embodiments, the use relates to the use of gold for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals in a sample comprising at least one alkali and / or alkaline earth metal and / or related metal, wherein the sample is substantially free of solvents, and wherein a thermoanalytical measurement is performed and the sample is in contact with the gold during the thermoanalytical measurement. The above statements regarding the first aspect of the invention apply analogously here.

[0070] In some embodiments, the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is at least a portion of an electrode and / or an electrode material. In some embodiments, during the thermoanalytical measurement, at least a portion of the at least one alkali and / or alkaline earth metal and / or related metal in the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is allowed to react with at least a portion of the gold. According to certain embodiments, the thermoanalytical measurement is a calorimetry. Alternatively or additionally, the thermoanalytical measurement can be a differential thermal analysis. In some embodiments, the thermoanalytical measurement is a dynamic differential calorimetry. Reference is made in full to the above statements regarding the first aspect of the invention.

[0071] A third aspect of the present invention relates to a system for the thermoanalytical determination of at least one alkali and / or alkaline earth metal and / or related metal, for example, lithium, comprising a thermoanalytical measuring device; a measuring container; and a drying device, wherein the measuring container comprises gold. The above statements regarding the first and second aspects of the invention apply analogously here. In some embodiments, the thermoanalytical measuring device can be a device for performing a method selected from the group consisting of DSC, ARC, MMC, DTA, STA, and combinations thereof. According to certain embodiments, the thermoanalytical measuring device is a differential scanning calorimeter. In some embodiments, the drying device is selected from an oven, a drying cabinet, a vacuum dryer, a rotary evaporator, a Schlenk line with a vacuum pump, and combinations thereof.The drying device can also be integrated into the measuring device. Reference is made in full to the above statements regarding the first and second aspects of the invention.

[0072] The above embodiments, refinements, and developments can be combined with one another as desired, where appropriate. Further possible refinements, refinements, and implementations of the invention also include combinations of previously described features of the invention not explicitly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

[0073] Examples

[0074] The invention will be explained in further detail below with reference to various examples. However, the invention is not limited to these examples.

[0075] Example 1: Description of the implementation of an exemplary process according to the invention with dynamic heating rate

[0076] A sample comprising at least one alkali and / or alkaline earth metal and / or related metal is dried and poured into a measuring container suitable for thermoanalytical measurements, e.g., a DSC crucible. In the case of crucibles without gold coating, additional gold foil or excess gold powder is added to the crucible as a reactant. In the case of gold-coated crucibles, simply filling the sample is sufficient. The crucible is then typically closed and subjected to the thermoanalytical measurement. In the case of DSC analysis, the crucible, together with a reference crucible, is subjected to a temperature change program. For this purpose, the sample and the reference are heated to a suitable temperature, e.g., 500 °C, at a dynamic heating rate, e.g., 3-30 K / min, under an inert gas stream. moderate

[0077] Process with isothermal

[0078] A sample comprising at least one alkali and / or alkaline earth metal and / or related metal is dried and poured into a measuring container suitable for thermoanalytical measurements, for example a DSC crucible. In the case of crucibles without a gold coating, an excess of gold foil or gold powder is added to the crucible as a reactant. In the case of gold-coated crucibles, simply filling the sample is sufficient. The crucible is then typically closed and subjected to the thermoanalytical measurement. In the case of a DSC analysis, the crucible is heated to a suitable temperature together with a reference crucible, and the sample and reference crucibles are subjected to an isothermal temperature treatment. The temperature of the isothermal heating segment is selected so that the exothermic reaction between the gold and the at least one alkali and / or alkaline earth metal and / or related metal is sufficiently rapid.The measurement is carried out under an inert gas stream. of a cathode material using a.

[0079] Sample preparation of a lithium-containing cathode material takes place under inert gas. For example, secondary batteries are first disassembled into their components, and the lithium-containing cathode material, with or without a carrier material, is then washed with a suitable solvent. The solvent is then removed, and an aliquot of the dried lithium-containing cathode material is transferred to a crucible. In the case of crucibles without a gold coating, an excess of gold foil or gold powder is also added to the crucible as a reactant. In the case of gold-coated crucibles, the cathode material is sufficient. The crucible is then sealed and subjected to DSC. The crucible, together with a reference crucible, is subjected to a temperature change program. For this purpose, the sample and the reference are heated to a suitable temperature, such as 500 °C, at a dynamic heating rate, e.g., 3-30 K / min, under an inert gas stream.

[0080] Evaluation

[0081] To determine the lithium concentration in the cathode material, a calibration measurement is performed with a suitable amount of pure lithium (calibration sample) in the selected crucible material for the sample measurements (gold-coated or with the addition of gold foil or gold powder, Calibration 7) and in an identical crucible without gold foil, gold powder, or gold coating (Calibration 2) using the same measurement parameters as the sample measurement. The measurement signal is then evaluated, preferably by integration, over the temperature range of the detected exothermic gold-lithium reaction. The heat of reaction generated by the formation of the gold-lithium alloy is determined by subtracting the integral value of Calibration 2 from the value of Calibration 1 (Au-Li reference). The measurement signal of the exothermic gold-lithium reaction is then integrated analogously to the sample measurement, and the heat of reaction generated is determined according to the reference (Au-Li sample).If you now divide the Au-Li sample by the Au-Li reference and multiply the ratio by the weight of the calibration measurement 1, you get the converted lithium content of the cathode material.

[0082] Example 4: Influence of gold

[0083] The procedure described in Example 1 was carried out using a lithium foil (weight: 0.7 mg) as a sample in a gold-coated stainless steel crucible and a lithium foil (weight: 0.4 mg) as a sample placed together with a gold foil in a stainless steel crucible. The procedure described in Example 1 was also carried out, except that the lithium foil (weight: 2 mg) was measured without gold added in a stainless steel crucible. The results are shown in Fig. 2. The dashed line corresponds to the measurement of the lithium foil in the gold-coated stainless steel crucible, the dash-dotted line to the measurement of the lithium foil together with the gold foil, and the solid line to the measurement without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). Clear measurement signals are evident in the presence of gold, which are attributable to the exothermic reaction between gold and lithium.The integral values ​​of the measurement signals are shown as hatched areas and are: 7663 au (lithium foil in gold-coated crucible), 1874 au (lithium foil with gold foil in stainless steel crucible), 263 au (lithium foil in stainless steel crucible).

[0084] Example 5: Determination of the charge state of electrode materials

[0085] The state of charge (SOC) can be determined from the lithium content in electrode materials, since the lithium content of the electrode material depends on the SOC. The procedure described in Example 3 was carried out using LiCoO2 as the electrode material. Furthermore, the procedure described in Example 3 was carried out using LiCoO2 as the electrode material without the presence of gold. Lithium foil was used as the calibration sample. The measurement results and parameters are presented in Table 1.

[0086] Table 1 : Measurement results of an exemplary method for determining the SOC in electrode materials

[0087] Material Crucible SOC Sample weight DSC Heating rate Inerter

[0088] / mg signal / K-min' 1 Gas flow

[0089] (N2)

[0090] [au]

[0091] / mL-min' 1

[0092] Li foil gold - 0.9 7663 10 20

[0093] Li foil stainless steel - 2.0 263 10 20

[0094] LiCoO2Gold 100 12.0 402 10 20 TI

[0095] LiCoO2Stainless steel 100 7.3 353 10 20

[0096] From the above results in Table 1, a lithium content in LiCoO2 of 0.06 mg can be determined.

[0097] Example 6: Influence of drying the sample

[0098] The procedure described in Example 3 was carried out using lithium manganate as the sample in a gold-coated stainless steel crucible. The sample was dried for one measurement and left undried for another. The result is shown in Fig. 3. The dashed line represents the measurement with the undried sample, and the solid line represents the measurement with the dried sample. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). Sample weights: 9.9 mg dried sample; 10.1 mg undried sample. The integral values ​​of the measurement signals are shown as hatched areas and are: 766.6 au (undried sample), 257 au (dried sample).

[0099] Comparing the measurement data for a dried and a non-dried sample, it is evident that the solvent causes an effect overlap. The signal curve is significantly larger than the observed signal curve of the gold-lithium reaction in the dried sample.

[0100] Example 7: Determination of sodium

[0101] The procedure described in Example 1 was performed using elemental sodium (initial weight: 1.7 mg) as a sample in a gold-coated stainless steel crucible. The procedure described in Example 1 was then repeated, except that the elemental sodium (initial weight: 2.2 mg) was measured in a stainless steel crucible without the addition of gold. The results are shown in Fig. 4. The dashed line corresponds to the measurement of sodium in the gold-coated stainless steel crucible, and the solid line corresponds to the measurement of sodium without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix;

[0102] Heating rate: 10 K / min; atmosphere: nitrogen (20 ml / min).

[0103] A clear measurement signal is visible in the presence of gold, which is due to the exothermic reaction between gold and sodium. The integral values ​​of the measurement signals are shown as hatched areas and are: 4963 au (sodium in the gold-coated crucible) and 1648 au (sodium in the stainless steel crucible). of potassium

[0104] The procedure described in Example 1 was performed using elemental potassium (weight: 1.1 mg) as a sample in a gold-coated stainless steel crucible. The procedure described in Example 1 was repeated, except that elemental potassium (weight: 0.4 mg) was measured without gold in a stainless steel crucible. The results are shown in Fig. 5. The dashed line corresponds to the measurement of potassium in the gold-coated stainless steel crucible, and the solid line corresponds to the measurement of potassium without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min).

[0105] A clear measurement signal is visible in the presence of gold, which is due to the exothermic reaction between gold and potassium. The integral values ​​of the measurement signals are shown as hatched areas and are: 1702 au (potassium in the gold-coated crucible) and 1226 au (potassium in the stainless steel crucible). of calcium

[0106] The procedure described in Example 1 was carried out using elemental calcium (weight: 1.3 mg) as a sample in a gold-coated stainless steel crucible. The result is shown in Fig. 6. Measurement parameters: Instrument: Netzsch STA 449 F3 Jupiter; Heating rate: 10 K / min; Atmosphere: Nitrogen (70 ml / min). A clear measurement signal is evident in the presence of gold, which is due to the exothermic reaction between gold and calcium. The integral value of the measurement signal is shown as a hatched area and is 1278 au. an isothermal

[0107] The procedure described in Example 2 was performed using a lithium foil (weight 6.0 mg) as a sample in a gold-coated stainless steel crucible. The same measurement was also performed without a sample as a reference. The result is shown in Fig. 7, with the measurement results shown at the top and the temperature change program used at the bottom. Measurement parameters: Netzsch DSC 204 F1 Phoenix; heating rate up to 225 °C: 30 K / min; isothermal for 1 h; atmosphere: nitrogen (20 ml / min).

[0108] Here, too, a clear measurement signal is visible in the presence of gold, which is due to the exothermic reaction between gold and lithium. The integral value of the measurement signal is shown as a hatched area and is 2690 au. The integral value of the reference is 235 au. of lithium manqanat as cathode material with SOC 100

[0109] The procedure described in Example 3 was performed using lithium manganate with an SOC 100 (initial weight: 9.9 mg) as a sample in a gold-coated stainless steel crucible. The procedure described in Example 3 was also performed, except that the lithium manganate was measured with SOC 100 (initial weight: 14 mg) without added gold in a stainless steel crucible. The results are shown in Fig. 8. The dashed line corresponds to the measurement of lithium manganate (SOC 100) in the gold-coated stainless steel crucible, and the solid line corresponds to the measurement of lithium manganate (SOC 100) without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integral values ​​of the measurement signals are shown as hatched areas and are: 257 au (with gold) and 207 au (without gold). It is shown that the use of gold results in a significant signal amplification, which can be attributed to the gold-lithium reaction. as cathode material with different

[0110] SOC

[0111] The procedure described in Example 3 was carried out using lithium manganate with a SOC of 100 (initial weight: 9.9 mg) and lithium manganate with a SOC of 50 (initial weight: 6.3 mg) as samples in a gold-coated stainless steel crucible. The results are shown in Fig. 9. The dashed line corresponds to the measurement of lithium manganate with SOC of 100, and the solid line to the measurement of lithium manganate with SOC of 50. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integral values ​​of the measurement signals are shown as hatched areas and are: 257 au (SOC of 100) and 381 au (SOC of 50).

[0112] Comparing the measured signals reveals that, along with the different states of charge (SOC), there is a significant difference in the determined integral values. Thus, the method according to the invention can be used to determine the state of charge of an electrode material.

[0113] 13: Measurement of lithium cobaltate as cathode material with SOC 100

[0114] The procedure described in Example 3 was performed using lithium cobaltate with a SOC 100 (initial weight: 12 mg) as a sample in a gold-coated stainless steel crucible. The procedure described in Example 3 was also performed, except that the lithium cobaltate was measured with SOC 100 (initial weight: 7.3 mg) without gold added in a stainless steel crucible. The results are shown in Fig. 10. The dashed line corresponds to the measurement of lithium cobaltate (SOC 100) in the gold-coated stainless steel crucible, and the solid line corresponds to the measurement of lithium cobaltate (SOC 100) without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integral values ​​of the measurement signals are shown as hatched areas and are: 412 au (with gold) and 384 au (without gold). It is shown that the use of gold results in a significant signal amplification, which can be attributed to the gold-lithium reaction. of lithium cobaltate as cathode material with different SOC

[0115] The procedure described in Example 3 was carried out using lithium cobaltate with an SOC of 100 (initial weight: 12.0 mg) and lithium cobaltate with an SOC of 0 (initial weight: 10.3 mg) as samples in a gold-coated stainless steel crucible. The results are shown in Fig. 11. The dashed line corresponds to the measurement of lithium cobaltate with an SOC of 100, and the solid line to the measurement of lithium cobaltate with an SOC of 0. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integral values ​​of the measurement signals are shown as hatched areas and are: 469 au (SOC of 100) and 270 au (SOC of 50).

[0116] Comparing the measured signals reveals that, along with the different states of charge (SOC), there is a significant difference in the determined integral values. Thus, the method according to the invention can be used to determine the state of charge of an electrode material.

[0117] 15: Measurement of lithium with different heating rates

[0118] 15A: The procedure described in Example 4 is carried out with the following parameters:

[0119] The weight of the foil in the crucible with Au coating was 7.8 mg, and in the crucible without coating, 5.5 mg. A Netzsch DSC 204 F1 Phoenix with a heating rate of 3 K / min and a nitrogen atmosphere (20 ml / min) was used as the measuring device. The results are shown in Fig. 12. The dashed line shows the measurement signal of the lithium foil in the stainless steel crucible. The solid line represents the measurement signal of the lithium foil in the stainless steel crucible without gold coating. The hatched areas below the lines represent the integrals of the exothermic signals. The figure clearly shows a difference in the measurement signals.

[0120] 15A: The procedure described in Example 4 was carried out with the following parameters: The initial weight of the foil in the crucible with Au coating was 3.3 mg, and in the crucible without coating 6.0 mg. The measuring device used was a Netzsch DSC 204 F1 Phoenix with a heating rate of 30 K / min and a nitrogen atmosphere (20 ml / min). The results are shown in Fig. 13. The dashed line shows the measurement signal of the lithium foil in the stainless steel crucible. The solid line represents the measurement signal of the lithium foil in the stainless steel crucible without gold coating. The hatched areas below the lines represent the integrals of the exothermic signals. The figure also shows a clear difference in the measurement signals.

Claims

Claims 1. A method for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals, comprising Providing a sample comprising at least one alkali and / or alkaline earth metal and / or related metal; Performing a thermoanalytical measurement of the sample; wherein the sample is in contact with gold during the thermoanalytical measurement, and wherein the sample is substantially free of solvents.

2. The method according to claim 1, wherein the sample is dried before performing the thermoanalytical measurement.

3. The method according to claim 1 or 2, wherein in the thermoanalytical measurement at least a portion of the at least one alkali and / or alkaline earth metal and / or related metal in the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is allowed to react with at least a portion of the gold.

4. Method according to one of the preceding claims, wherein the thermoanalytical measurement is a calorimetry and / or a differential thermal analysis, in particular wherein the thermoanalytical measurement is a dynamic differential calorimetry.

5. Method according to one of the preceding claims, wherein the thermoanalytical measurement comprises carrying out a temperature change program, wherein the Temperature change program comprises heating the sample from a first temperature to a second temperature by means of a heating rate, wherein the second temperature is at most 1000 °C, optionally wherein the heating rate is 3 to 30 K / min, and / or wherein the temperature change program comprises holding the sample at a temperature for a holding time, optionally wherein the temperature is at least 20 °C and / or wherein the holding time is at least 15 min.

6. Method according to one of the preceding claims, wherein the gold is present in excess relative to the at least one alkali and / or alkaline earth metal and / or related metal and / or wherein the weight ratio of the sample to the gold is 1:> 1.

7. Method according to one of the preceding claims, wherein the sample is filled into a measuring container before the thermoanalytical measurement and the measurement is carried out with the sample in the measuring container.

8. The method according to claim 7, wherein the measuring container comprises the gold and / or wherein the sample is mixed with gold before being filled into the measuring container and the sample is filled into the measuring container with the gold.

9. The method according to claim 7 or 8, wherein the measuring container is gold-plated or consists of gold and / or wherein the measuring container can be a high-pressure container.

10. Method according to one of the preceding claims, wherein the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is at least part of an electrode and / or electrode material.

11. The method of claim 10, wherein the method comprises determining the state of charge (SOC) of the electrode and / or the electrode material.

12. Use of gold for the thermoanalytical determination of alkali and / or alkaline earth metals and / or related metals in a sample comprising at least one alkali and / or alkaline earth metal and / or related metal, wherein the sample is substantially free of solvents, and wherein the sample is in contact with the gold during the thermoanalytical measurement.

13. Use according to claim 12, wherein the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is at least a part of an electrode and / or an electrode material.

14. Use according to claim 12 or 13, wherein in the thermoanalytical measurement at least a portion of the at least one alkali and / or alkaline earth metal and / or related metal in the sample comprising at least one alkali and / or alkaline earth metal and / or related metal is allowed to react with at least a portion of the gold.

15. Use according to one of claims 12 to 14, wherein the thermoanalytical measurement is a calorimetry and / or a differential thermal analysis, in particular wherein the thermoanalytical measurement is a dynamic differential calorimetry.

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