Thermal analysis determination of alkali and / or alkaline earth and / or related metals

Abstract

The present invention relates to a method for the determination of alkali and / or alkaline earth and / or related metals by thermal analysis.

Description

[0001] Invention Field

[0002] This invention relates to a method for the thermal analysis determination of alkali metals and / or alkaline earth metals and / or related metals. The invention also relates to the use of gold in the thermal analysis of samples containing at least one alkali metal and / or alkaline earth metal and / or related metal.

[0003] Existing technology

[0004] The development of analytical methods for studying the properties of substances and for identifying and quantifying components in compositions has long been of great importance in industry and research. However, depending on the analytical method, considerable effort is often required to prepare the sample to obtain representative measurement results. Furthermore, information is often only obtained about a portion of the sample (e.g., its surface). Therefore, there is a need to develop simple and uncomplicated analytical methods that provide the highest possible information content about the sample.

[0005] The determination of alkali metals is particularly important in battery technology. In existing technologies, wet chemical methods are known for determining lithium in battery materials. In this process, the sample to be analyzed (usually a solid) must first be quantitatively converted into a solution by a suitable decomposition method (e.g., acid decomposition). Insoluble components are filtered out. The resulting analytical solution is then measured against a standard solution with a known analyte content using spectroscopic methods (e.g., atomic absorption spectrometry). By comparing the measured intensity of the analytical solution with that of the standard solution, the concentration of the analyte is determined. This method allows for the determination of the total analyte content in the solid. However, these methods suffer from the drawback of complex sample preparation.

[0006] Another method for determining lithium is solid-state lithium nuclear magnetic resonance (Festkörper-Li-NMR). If necessary, the solid can also be measured directly in the rotor as a solid after a complex sample preparation process, without a dissolution process. However, nuclear magnetic resonance (NMR) is often difficult or limited by the presence of other atomic nuclei with large quadrupole moments. This mainly involves 3d-series transition metals related to electrode materials.

[0007] Furthermore, conventional spectroscopic methods are known for the determination of alkali metals in solids. For example, energy-dispersive X-ray spectroscopy provides local information about the alkali metal content. However, determining the total alkali metal content in a sample requires that the analyte be uniformly distributed throughout the sample. Moreover, multiple analyses are typically needed to determine the local alkali metal content.

[0008] Therefore, there is a need to develop a method for determining alkali metals and / or alkaline earth metals that is simple, uncomplicated, and rapidly executable. Furthermore, a method for determining alkali metals and / or alkaline earth metals is needed that allows for both surface inspection and measurement of the entire sample volume. Additionally, a simple, uncomplicated, and rapid method is needed to determine the content of alkali metals and / or alkaline earth metals in a sample. Furthermore, a method is needed to determine alkali metals and / or alkaline earth metals in electrode materials, and / or to determine the content of alkali metals and / or alkaline earth metals in electrode materials. Finally, a method is needed to determine the state of charge (SOC) of the battery electrodes. Summary of the Invention

[0009] In a first aspect, the present invention provides a method for thermal analysis of alkali metals and / or alkaline earth metals and / or related metals, wherein the method comprises: providing a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal; and performing thermal analysis on the sample. In this process, the sample is in contact with gold during the thermal analysis measurement, and the sample is substantially solvent-free.

[0010] The method according to the invention provides a simple, uncomplicated, and rapid determination of alkali metals and / or alkaline earth metals and / or related metals in samples containing at least one alkali metal and / or alkaline earth metal and / or related metals. It avoids the complex sample preparation required by wet chemical methods. Unlike methods that can only examine a portion of a sample (e.g., the surface), the method according to the invention allows for analysis of the entire sample volume. Furthermore, the method according to the invention provides a simple, uncomplicated, and rapid determination of the content of at least one alkali metal and / or alkaline earth metal and / or related metal in a sample. Further, the method according to the invention enables the determination of alkali metals and / or alkaline earth metals and / or related metals in electrodes and / or electrode materials, and / or the determination of the content of alkali metals and / or alkaline earth metals and / or related metals in electrodes and / or electrode materials. This, in particular, makes it possible to determine the state of charge of battery electrodes simply and uncomplicated. Compared to prior art methods (e.g., NMR), this method requires lower investment costs. Moreover, the method according to the invention has low technical complexity, thus requiring a lower level of experience to implement.

[0011] In another aspect, the present invention provides the use of gold in a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal for thermal analysis measurements or determinations of alkali metals and / or alkaline earth metals and / or related metals. The sample is substantially solvent-free in this process and is in contact with gold during the thermal analysis measurements.

[0012] By virtue of the application according to the invention, it becomes possible to perform a simple, uncomplicated, and rapid determination of alkali metals and / or alkaline earth metals and / or related metals in samples containing at least one alkali metal and / or alkaline earth metal and / or related metals. The advantages of the method described above according to the invention also apply to the application according to the invention.

[0013] Other aspects of the invention may be learned from the dependent claims and detailed description. Attached Figure Description

[0014] The accompanying drawings are intended to illustrate embodiments of the invention and to aid in a further understanding of the invention. In conjunction with the specification, the drawings are used to explain the concepts and principles of the invention. Other embodiments and the many advantages described above will become apparent from the accompanying drawings. Elements in the drawings are not necessarily shown to scale relative to each other. Unless otherwise stated, in the drawings, identical, functionally equivalent, and equivalent elements, features, and components use the same reference numerals.

[0015] Figure 1 A schematic diagram of a method for thermal analysis determination of alkali metals and / or alkaline earth metals and / or related metals according to the present invention, wherein the method comprises: providing a sample 2 containing at least one alkali metal and / or alkaline earth metal and / or related metal; and performing thermal analysis on the sample 2.

[0016] Figure 2 Schematic diagram of DSC measurement of lithium-containing samples. Dashed lines represent measurement signals according to an exemplary method of the present invention, wherein lithium foil is measured in a gold-plated stainless steel crucible. Dotted lines represent measurement signals according to an exemplary method of the present invention, wherein lithium foil and gold foil are measured simultaneously in a stainless steel crucible. Solid lines represent measurement signals from differential scanning calorimetry (DSC) measurements of lithium foil in a stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0017] Figure 3 Schematic diagram of DSC measurements of dried and undried lithium-containing samples. The dashed line represents the measurement signal obtained from DSC measurements of undried lithium manganese oxide samples in a gold-plated stainless steel crucible. The solid line represents the measurement signal according to an exemplary method of the present invention, wherein measurements were performed on dried lithium manganese oxide samples in a gold-plated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0018] Figure 4 Schematic diagram of DSC measurement of sodium-containing samples. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein a dry sodium-containing sample is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal obtained by DSC measurement of a dry sodium-containing sample in a stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0019] Figure 5 Schematic diagram of DSC measurement of potassium-containing samples. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein a dry potassium-containing sample is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal obtained by DSC measurement of a dry potassium-containing sample in a stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0020] Figure 6 : A schematic diagram of the measurement signal according to an exemplary method of the present invention, wherein a dry calcium-containing sample is measured in a gold-plated stainless steel crucible. The shaded area below the line represents the integral of the exothermic signal.

[0021] Figure 7 Top figure: Schematic diagram of DSC measurement in the isothermal heating section of a lithium-containing sample. The dashed line represents the measurement signal according to the exemplary method of the present invention, wherein lithium foil is measured in a gold-plated stainless steel crucible using the isothermal heating section. The solid line represents the measurement signal of DSC measurement using the isothermal heating section as a reference result in a stainless steel crucible without a sample. The shaded areas below the lines represent the integrals of the exothermic signal and the reference signal, respectively. Bottom figure: Schematic diagram of the temperature change procedure used in the DSC measurement.

[0022] Figure 8 Schematic diagram of DSC measurement of lithium manganese oxide as cathode material with a SOC of 100. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein dry lithium manganese oxide with a SOC of 100 is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal obtained by DSC measurement of dry lithium manganese oxide with a SOC of 100 in a stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0023] Figure 9 Schematic diagrams of DSC measurements of lithium manganese oxide as cathode material with SOCs of 100 and 50. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein the measurement is performed on dry lithium manganese oxide with an SOC of 100 in a gold-plated stainless steel crucible. The solid line represents the measurement signal according to an exemplary method of the present invention, wherein the measurement is performed on dry lithium manganese oxide with an SOC of 50 in a gold-plated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0024] Figure 10 Schematic diagram of DSC measurement of lithium cobalt oxide as cathode material at SOC of 100. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein dry lithium cobalt oxide with an SOC of 100 is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal of DSC measurement of dry lithium manganese oxide with an SOC of 100 in a stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0025] Figure 11 Schematic diagrams of DSC measurements of lithium cobalt oxide as cathode material with SOCs of 100 and 0. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein dry lithium cobalt oxide with an SOC of 100 is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal according to an exemplary method of the present invention, wherein dry lithium cobalt oxide with an SOC of 0 is measured in a gold-plated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0026] Figure 12 Schematic diagram of DSC measurement of elemental lithium at a heating rate of 3 K / min. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein the lithium foil is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal according to an exemplary method of the present invention, wherein the lithium foil is measured in an unplated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal.

[0027] Figure 13 Schematic diagram of DSC measurement of elemental lithium at a heating rate of 30 K / min. The dashed line represents the measurement signal according to an exemplary method of the present invention, wherein the lithium foil is measured in a gold-plated stainless steel crucible. The solid line represents the measurement signal according to an exemplary method of the present invention, wherein the lithium foil is measured in an unplated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal. Invention Details

[0029] definition

[0030] Unless otherwise defined, the technical and scientific terms used herein shall have the meanings commonly understood by those skilled in the art in the field of this invention.

[0031] Unless otherwise stated or clearly indicated from the context, all quantities specified in this invention are expressed as weight percentages (wt.%).

[0032] The term "related metals" is not intended to limit the scope of this invention. Here, "related metals" refers to metals whose properties are similar to those of alkali metals and / or alkaline earth metals. For example, in terms of their valence, they particularly include monovalent and divalent metals, such as silver or copper as monovalent metals, and most heavy metals as divalent metals, such as copper, zinc, or cadmium.

[0033] The term "thermal analysis measurement" is not particularly limited within the scope of this invention, but it does not include purely gravimetric methods. Therefore, the term "thermal analysis measurement" within the scope of this invention does not include thermogravimetric analysis itself, but includes, for example, simultaneous thermal analysis (STA). Within the scope of this invention, the terms "thermal analysis measurement" and "thermal analysis" can be used synonymously. It is well known that thermal analysis measurements study the changes in the physical and chemical properties of a sample with temperature. In thermal analysis measurements, the changes in the physical and / or chemical properties of a sample with temperature are measured while the sample undergoes a temperature change procedure. That is, in thermal analysis measurements, the sample is excited, resulting in an observable reaction. A response signal corresponding to this observable reaction is measured using a measuring device. A thermal analysis measurement curve is calculated using data including the response signal as a function of time and the excitation, thereby enabling the identification of thermal effects. In some embodiments, thermal analysis measurements are selected from the group consisting of differential scanning calorimetry (DSC), accelerated calorimetry (ARC), multi-module calorimetry (MMC), differential thermal analysis (DTA), simultaneous thermal analysis (STA), and combinations thereof.

[0034] The term "calorimetry" is not particularly limited within the scope of this invention. As is well known, calorimetry refers to the measurement of heat associated with biological, chemical, or physical processes, which may be exothermic or endothermic. A calorimeter is used to perform such measurements.

[0035] The term "differential scanning calorimetry" is not particularly limited within the scope of this invention. As is well known, differential scanning calorimetry (DSC) measures the heat released or absorbed by a sample during heating, cooling, or isothermal processes. In DSC, both the first measuring container containing the sample and the empty second measuring container undergo the same temperature change program. The first and second measuring containers are identical. The empty second measuring container is called the reference. Due to the heat capacity of the sample and exothermic or endothermic processes (such as melting or evaporation) and / or phase changes, heat energy flows into or out of the sample during the process under study, resulting in a temperature difference between the sample and the reference.

[0036] The term "sample" is not particularly limited within the scope of this invention, but a sample may contain at least one alkali metal and / or at least one alkaline earth metal and / or at least one related metal. The terms "sample" and "analytical sample" may be used synonymously. Generally, a sample refers to the entirety of the material being tested. Under normal conditions, a sample may be solid, liquid, or waxy. Particularly under normal conditions, a sample may be solid.

[0037] Within the scope of this 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" may be used synonymously.

[0038] The term "electrode" is not particularly limited within the scope of this invention. As is well known, an electrode is an electrical conductor that interacts with paired electrodes (anode-cathode) and a medium situated between the two electrodes. Within the scope of this invention, an electrode can be a cathode and / or an anode. In some embodiments, the electrode is an electrode of a battery—e.g., a lithium battery, a sodium battery, an alkaline manganese battery, a tin-based battery, a sulfur-based battery, a zinc-based battery, a polymer battery, etc.—but is not limited thereto. Batteries herein include, in particular, primary and secondary batteries, without particular limitation.

[0039] The term "solvent" is not particularly limited within the scope of this invention. As is well known, a solvent is a substance capable of dissolving and diluting gases, liquids, or solids without causing a chemical reaction between the solvent, the substance to be dissolved, and the dissolved substance during the dissolution process. Typically, the solvent used is a liquid, such as water and / or liquid inorganic and / or organic substances, and mixtures thereof, with suitable and unrestricted additives added as necessary. Within the scope of this invention, the solvent is a liquid under normal conditions. A suitable solvent is, in particular, one that does not distort the analytical results by removing at least one alkali metal and / or alkaline earth metal and / or related metals from the analyte. Analytical chemists are familiar with suitable solvents in this context.

[0040] The term "substantially solvent-free" is not particularly limiting within the scope of this invention. A sample is considered substantially solvent-free if the solvent content (based on the total weight of the sample) is less than 0.5 wt.%, preferably less than 0.1 wt.%, and particularly preferably less than 0.01 wt.%. Alternatively or additionally, if the vapor pressure of the solvent content in the sample is at most 10... - ¹mbar, preferably up to 10 - ² millibars, with a preferred maximum of 10. - If the vapor pressure is 3 millibars, then the sample is essentially solvent-free. Here, the vapor pressure can be measured, for example, by a suitable pressure gauge—such as on a Schlenk-Line or on the sample container.

[0041] Within the scope of this invention, the term "reference container" refers to an empty second measuring container, wherein the first measuring container contains the sample to be tested, and the first and second measuring containers are identical. "Identical" means that the measuring containers have the same properties, particularly the same structure, the same material, the same dimensions, and the same weight.

[0042] The term "fundamentally inert" is not particularly limited within the scope of this invention. In some embodiments, the atmosphere is substantially inert if the water content in the atmosphere is at most 10 ppm, preferably at most 5 ppm, particularly preferably at most 1 ppm, and the oxygen content is at most 10 ppm, preferably at most 5 ppm, particularly preferably at most 1 ppm.

[0043] A first aspect of the invention relates to a method for thermal analysis of alkali metals and / or alkaline earth metals and / or related metals, wherein the method comprises: providing a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal; and performing thermal analysis on the sample. The sample is substantially solvent-free and is in contact with gold during the thermal analysis.

[0044] Therefore, the present invention may include: a sample containing at least one alkali metal (i.e., one alkali metal or two or more alkali metals); a sample containing at least one alkaline earth metal (i.e., one alkaline earth metal or two or more alkaline earth metals); a sample containing at least one related metal (i.e., one related metal or two or more related metals); or a sample containing a mixture of the above metals (i.e., a mixture of at least one alkali metal and at least one alkaline earth metal, a mixture of at least one alkali metal and at least one related metal, a mixture of at least one alkaline earth metal and at least one related metal, or a mixture of at least one alkali metal, at least one alkaline earth metal, and at least one related metal). According to some embodiments, the sample contains at least one alkali metal, i.e., one alkali metal or two or more alkali metals. According to some embodiments, the sample contains at least one alkaline earth metal, i.e., one alkaline earth metal or two or more alkaline earth metals. According to some embodiments, the sample contains at least one related metal, i.e., one related metal or two or more related metals. According to some embodiments, the sample contains at least one alkali metal and at least one alkaline earth metal. According to some embodiments, the sample contains at least one alkali metal and at least one related metal. According to some embodiments, the sample contains at least one alkaline earth metal and at least one related metal. According to some embodiments, the sample contains at least one alkali metal, at least one alkaline earth metal, and at least one related metal.

[0045] The inventors unexpectedly discovered that when a sample comes into contact with gold, a measurement signal can be generated in the thermal analysis of the sample for a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal. Without relying on any specific theory, it is assumed that an exothermic reaction occurs between gold and the alkali metal and / or alkaline earth metal and / or related metal during the thermal analysis measurement; this reaction 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 found that the presence of solvents interferes with the determination and distorts the measurement signal. The evaluation of measurement signals in thermal analysis measurements is well known to those skilled in the art.

[0046] Without being limited to a specific theory, it is further hypothesized that the reaction between gold and alkali metals and / or alkaline earth metals and / or related metals will produce alloys and / or solid solutions and / or intermetallic compounds.

[0047] Here, "contact" means that at least a portion of the sample is in contact with at least a portion of the gold, and / or that 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 is in contact with the gold such that the alkali metals and / or alkaline earth metals and / or related metals in the sample can react with the gold.

[0048] Here, thermal analysis measurements require the use of commercially available analytical instruments, such as calorimeters. These instruments are readily available on the market, and it is best to operate them according to the instructions of the respective manufacturers.

[0049] 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 may be selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr), and mixtures thereof. The alkaline earth metal may be selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and mixtures thereof. The related metal may be selected, in particular, from other monovalent and divalent metals, such as silver (Ag), copper (Cu), zinc (Zn), cadmium (Cd), and mixtures thereof. In a preferred embodiment, 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 some 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 some 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 some embodiments, the sample contains lithium. According to some embodiments, this method is a method for thermal analysis to determine lithium.

[0050] In some embodiments, the method is a method for thermal analysis to determine the content of at least one alkali metal and / or alkaline earth metal and / or related metals in a sample. In some embodiments, the method is a method for thermal analysis to determine the lithium content in a sample (particularly electrode materials). According to some embodiments, the method is a method for calorimetric determination of the lithium content in a sample (particularly electrode materials).

[0051] In some embodiments, the sample is dried prior to thermal analysis measurements. There are no particular limitations on the drying of the sample. According to some embodiments, drying apparatus can be used for sample drying. Suitable drying apparatus may be an oven, such as a muffle furnace and / or a drying cabinet. Alternatively or additionally, the sample may be dried in situ within the measuring instrument during the measurement, for example, by running a heating program. Alternatively or additionally, the sample may be dried under vacuum conditions. Suitable apparatus for drying in a vacuum includes vacuum desiccators, rotary evaporators, and / or Schlenk lines with vacuum pumps. Drying the sample ensures that it is substantially solvent-free. Here, the drying of the sample can be specifically performed so that the sample is solvent-free after drying. Drying the sample prior to thermal analysis measurements is advantageous because it eliminates the need for the sample to be substantially solvent-free from the outset, thus providing greater flexibility in sample selection.

[0052] In the method according to the invention, the sample can also be prepared under inert gas conditions, as will be further described below. Here, "inert gas" refers to a gas that must be excluded from reacting with the sample under operating conditions so that the inert gas can be determined based on at least one alkali metal and / or alkaline earth metal and / or related metal to be measured. For example, when using lithium, nitrogen causes the formation of lithium nitride; therefore, argon is preferably used as the inert gas, for example, in lithium determination.

[0053] In some embodiments, during the thermal analysis measurement, at least a portion of the alkali metal and / or alkaline earth metal and / or related metal in a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is reacted with at least a portion of gold. Here, "causing a reaction" means that the measurement conditions of the thermal analysis measurement are set such that at least a portion of the at least one alkali metal and / or alkaline earth metal and / or related metal reacts with at least a portion of gold. The selection of the measurement conditions depends on the properties of the sample and the properties of the alkali metal and / or alkaline earth metal and / or related metal. The measurement signal generated by the thermal analysis measurement can determine the temperature range within which the alkali metal and / or alkaline earth metal and / or related metal reacts with gold.

[0054] According to some embodiments, the thermal analysis measurement can be calorimetry and / or thermal measurement. Alternatively or additionally, the thermal analysis measurement can also be differential thermal analysis (DTA). In some embodiments, the thermal analysis measurement is selected from the group consisting of: differential scanning calorimetry (DSC), accelerated calorimetry (ARC), multi-module calorimetry (MMC), differential thermal analysis (DTA), simultaneous thermal analysis (STA), and combinations thereof. According to some embodiments, the thermal analysis measurement is selected from the group consisting of DSC, ARC, MMC, and STA. In some embodiments, the thermal analysis measurement is differential scanning calorimetry (DSC).

[0055] According to some embodiments, thermal analysis measurements may include the execution of a temperature change procedure. This temperature change procedure may include a dynamic heating rate and / or an isothermal heating section. In some embodiments, the temperature change procedure includes heating a sample (and optionally a reference) from a first temperature to a second temperature by 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 tested and the alkali metal and / or alkaline earth metal and / or related metal. To determine a suitable temperature and heating rate, for example, the method according to the invention may be performed first, wherein the sample (and optionally a reference) is heated by the temperature change procedure at a high heating rate (e.g., 30 K / min) from, for example, 10°C or room temperature (22°C) to, for example, 1600°C, or for example, to 1000°C. Based on the measurement signal, the temperature range in which the reaction occurs between the alkali metal and / or alkaline earth metal and / or related metal and gold can be estimated. Subsequently, the measurement parameters of the temperature change procedure can be fine-tuned.

[0056] In some embodiments, the first temperature is -10°C to 150°C, preferably 0°C to 100°C, particularly preferably 20°C to 40°C or 0°C to 20°C, the latter being applicable, for example, in the determination of Cs. According to some embodiments, the second temperature is at least 300°C, preferably at least 400°C, particularly preferably at least 500°C. According to some embodiments, the second temperature is at most 1600°C, preferably at most 1200°C, particularly preferably at most 1000°C. For some samples, such as in the determination of lithium, lower second temperatures—e.g., at most 900°C, 800°C, 700°C, 600°C, or 500°C—may also be applicable. The heating rate here can be, for example, from 3 K / min to 30 K / min.

[0057] Alternatively or additionally, the temperature change procedure may include holding the sample (isothermally) and optionally a reference at a certain temperature for a period of time. As mentioned above, the determination of the temperature and holding time also depends on the sample to be tested and the type and properties of the alkali metal and / or alkaline earth metal. As mentioned above, this can be determined by suitable preliminary tests. In some embodiments, the temperature is at least 20°C, for example at least 25°C, preferably above 25°C. Lower temperatures are advantageous, for example, for the determination of cesium. For other elements (e.g., lithium), higher temperatures—e.g., 200°C to 240°C—are advantageous. In some embodiments, the temperature is from 20°C to 1000°C. Alternatively or additionally, the holding time may be at least 15 minutes, for example at least 0.5 hours. In some embodiments, the holding time is from 15 minutes to 12 hours, for example from 0.5 hours to 10 hours, preferably from 1 hour to 8 hours, and particularly preferably from 1.5 hours to 5 hours.

[0058] According to some embodiments, an inert gas flow is provided for thermal analysis measurements. During the thermal analysis measurement, the inert gas flow is guided to flow over and / or through the sample. Here, the inert gas in the inert gas flow can be helium (He), argon (Ar), and / or nitrogen (N2), and can be appropriately selected according to the analyte. In some embodiments, the flow rate of the inert gas flow is from 5 ml / min to 150 ml / min, preferably from 10 ml / min to 100 ml / min, and particularly preferably from 15 ml / min to 80 ml / min.

[0059] In some embodiments, the gold content is excessive relative to at least one alkali metal and / or alkaline earth metal and / or related metal. Here, excess refers to molar excess. This excess is particularly advantageous when a quantitative or semi-quantitative determination of the content of at least one alkali metal and / or alkaline earth metal and / or related metal in a sample is required. Whether an excess exists can be determined by appropriate preliminary consideration and / or simple pre-experiments. Here, excess refers to molar excess. Alternatively or additionally, the weight ratio of the sample to gold can be 1:≥1. This further improves the determination of the content of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample. In some embodiments, the weight ratio of the sample to gold is between 1:1 and 1:100. According to some embodiments, the content of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample is at most 10 wt.%, preferably at most 3 wt.%, and particularly preferably at most 1 wt.%.

[0060] According to some embodiments, before performing thermal analysis measurements, the sample is loaded into a measuring container, and the sample is measured within the measuring container. There are no particular limitations on the measuring container, but it must be suitable for thermal analysis measurements. In some embodiments, before performing thermal analysis measurements, the sample is loaded into a first measuring container, and the measurement is performed with the sample in the first measuring container and the second measuring container empty. Here, the first and second measuring containers are identical. The second measuring container is referred to as a reference. Alternatively or additionally, the sample may be weighed before being placed into the measuring container. In some embodiments, the sample amount is from 0.5 mg to 150 mg, preferably from 1 mg to 100 mg, and particularly preferably from 5 mg to 20 mg.

[0061] In some embodiments, the measuring container contains gold. According to some embodiments, the first measuring container contains gold. Here, the gold can be present in the form of gold foil and / or gold powder. For example, gold can be placed in the measuring container, and then the sample can be loaded into the measuring container and / or weighed in the measuring container. Alternatively or additionally, the sample can be mixed and / or mixed with gold before being loaded into the measuring container, and then the gold-containing sample can be loaded into the measuring container. Here, the gold can be present in the form of gold foil and / or gold powder. Alternatively or additionally, the measuring container can be gold-plated and / or coated with gold, or even made entirely of gold. Here, "gold-plated" means that at least a portion of the measuring container is made of gold. Here, the gold is arranged to allow it to contact the sample. According to the invention, the possibility of the measuring container being made of gold is not excluded. In particular, commercially available gold of purity (e.g., 99.90% or 99.95%) is used.

[0062] In some embodiments, the measuring container is a crucible. In some embodiments, the measuring container is a high-pressure vessel and / or a high-pressure crucible. However, the measuring container does not necessarily have to be a high-pressure vessel.

[0063] In some embodiments, the measuring vessel used to perform the thermal analysis measurements is completely sealed. This is advantageous when the thermal analysis measurements and / or the method are performed under inert conditions and / or in a substantially inert atmosphere. “Inert conditions” refers to conditions that largely exclude the sample from contact with water and oxygen—that is, the water and oxygen content is within the limits specified above.

[0064] In some embodiments, sample preparation, drying, loading into a measuring container, and / or thermal analysis are performed under inert conditions and / or a substantially inert atmosphere. This is advantageous when the sample is sensitive to air and / or water.

[0065] In some implementations, the thermal analysis measurement includes performing a single thermal analysis calibration measurement or multiple thermal analysis calibration measurements. Here, the thermal analysis calibration measurement is also performed using calibration samples that are essentially solvent-free.

[0066] In some embodiments, thermal analysis measurements include performing thermal analysis calibration measurements. The thermal analysis calibration measurements are performed using a calibration sample containing a known amount of at least one alkali metal and / or alkaline earth metal and / or related metal. Here, the thermal analysis measurements of the sample and the calibration measurements of the calibration sample are performed under the same measurement conditions. By comparing the measurement signals from the thermal analysis calibration measurements and the thermal analysis measurements, the content of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample can be determined. This assessment can be accomplished by integrating the measurement signal over a certain temperature range. This temperature range depends on the sample and the type and properties of the at least one alkali metal and / or alkaline earth metal and / or related metal. In particular, this temperature range is determined by the heat of reaction of the at least one alkali metal and / or alkaline earth metal and / or related metal with gold. For example, the ratio of the integrated values ​​obtained by integrating the measurement signals can be used to determine the content of at least one alkali metal and / or alkaline earth metal and / or related metal.

[0067] In some embodiments, a first thermal analysis calibration measurement and a second thermal analysis calibration measurement are performed. The first and second thermal analysis calibration measurements are performed under the same measurement conditions. Here, in the first thermal analysis calibration measurement, the calibration sample is in contact with gold, while in the second thermal analysis calibration measurement, the calibration sample is not in contact with gold. For example, for the first thermal analysis calibration measurement, the calibration sample is mixed with gold, and the mixture of the calibration sample and gold is measured. In the second thermal analysis calibration measurement, only the calibration sample is measured. By comparing the measurement signals of the first and second thermal analysis calibration measurements, the heat of reaction between at least one alkali metal and / or alkaline earth metal and / or related metal and gold can be determined. This heat of reaction can be used as a reference value for determining the content of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample. Here, for example, the measurement signals of the first and second thermal analysis calibration measurements can be integrated over a certain temperature range, and the resulting integrated values ​​can be subtracted to obtain the reference value. In particular, the reference value can be determined by subtracting the integrated value of the measurement signal of the second thermal analysis calibration measurement from the integrated value of the measurement signal of the first thermal analysis calibration measurement.

[0068] In some embodiments, the performance of thermal analysis measurements of the sample includes an evaluation of the measurement signal obtained through the thermal analysis. This evaluation can be achieved by integrating the measurement signal over a certain temperature range. This temperature range depends on the sample and the type and properties of at least one alkali metal and / or alkaline earth metal and / or related metal. By integrating the measurement signal, an integral value can be obtained. The content of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample can be determined by the ratio of this integral value to a reference value. Here, the reference value can be determined as described above or may be known and / or stored in the apparatus used to evaluate the thermal analysis measurements.

[0069] According to some embodiments, a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is at least a portion of an electrode. Alternatively or additionally, a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is at least a portion of an electrode material. According to some embodiments, a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is an electrode. Alternatively or additionally, a sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is an electrode material. In some embodiments, the electrode is a battery electrode. According to some embodiments, the electrode material is a battery electrode material. 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. Here, the alkali metal is preferably selected from the group consisting of lithium, sodium, and optionally cesium. In some embodiments, the electrode material is a cathode material.

[0070] According to some embodiments, the electrode material comprises at least one transition metal, which is not particularly limited. However, the electrode material is not limited to such metals and includes metals present in conventional batteries as defined above. In some embodiments, the electrode material comprises multiple transition metals.

[0071] In some embodiments, the sample is electrode material, wherein sample preparation includes extracting the electrode material from the battery and cleaning the electrode material. Cleaning can be performed using a suitable solvent (as exemplified above), which is not limited to a specific solvent and can be tailored to the electrode material. The electrode material is then preferably dried using the sample drying method described above.

[0072] According to some embodiments, the method includes determining the state of charge (SOC) of the electrode and / or electrode material. The method can also be used to determine the content of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample, for example, the determination of alkali metal content, particularly lithium content. The state of charge of the electrode and / or electrode material can be inferred from the content of at least one alkali metal and / or alkaline earth metal and / or related metal (e.g., alkali metal content). The determination of the content of at least one alkali metal and / or alkaline earth metal and / or related metal (e.g., alkali metal content) can be performed by the above-described thermal analysis calibration measurement and / or by using the above-described reference values. In some embodiments, the sample can be electrode material of a lithium battery, and the calibration sample can be lithium foil.

[0073] According to the present invention, an exemplary method for thermal analysis to determine alkali metals and / or alkaline earth metals is illustrated as follows: Figure 1 As shown, the method includes: providing a sample 1 containing alkali metals and / or alkaline earth metals; and performing thermal analysis on the sample 2.

[0074] A second aspect of the invention relates to the use of gold in the thermal analysis or determination of samples containing at least one alkali metal and / or alkaline earth metal and / or related metals, wherein the sample is substantially solvent-free and the sample is in contact with gold during the thermal analysis. In some embodiments, this use relates to the thermal analysis determination of alkali metals and / or alkaline earth metals and / or related metals in samples containing at least one alkali metal and / or alkaline earth metal and / or related metals, wherein the sample is substantially solvent-free and the sample is in contact with gold during the thermal analysis. The description of the first aspect of the invention above is similarly applicable here.

[0075] In some embodiments, the sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is at least a portion of the electrode and / or the electrode material. In some embodiments, during the thermal analysis measurement, at least a portion of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample reacts with at least a portion of gold. According to some embodiments, the thermal analysis measurement is calorimetry. Alternatively or additionally, the thermal analysis measurement may be differential calorimetry. In some embodiments, the thermal analysis measurement is dynamic differential calorimetry. The above description of the first aspect of the invention is detailed below.

[0076] A third aspect of the invention relates to a system for the thermal analysis determination of at least one alkali metal and / or alkaline earth metal and / or related metal (e.g., lithium), the system comprising a thermal analysis measuring apparatus, a measuring container, and a drying apparatus, wherein the measuring container contains gold. The description of the first and second aspects of the invention above is similarly applicable herein. In some embodiments, the thermal analysis measuring apparatus may be an apparatus for performing a method selected from the group consisting of DSC, ARC, MMC, DTA, STA, and combinations thereof. According to some embodiments, the thermal analysis measuring apparatus is a dynamic differential scanning calorimeter. In some embodiments, the drying apparatus is selected from ovens, drying cabinets, vacuum dryers, rotary evaporators, Schlenk lines with vacuum pumps, and combinations thereof. The drying apparatus may also be integrated into the measuring apparatus. Please refer to the description of the first and second aspects of the invention above.

[0077] The above-described embodiments, designs, and improvements can be combined arbitrarily, as long as they are meaningful. Other possible designs, improvements, and implementations of the present invention include combinations of features not explicitly mentioned in the foregoing descriptions. In particular, those skilled in the art can add various aspects as improvements or additions to the corresponding basic forms of the present invention.

[0078] Example

[0079] The invention will now be described in more detail with reference to various examples. However, the invention is not limited to these examples.

[0080] Example 1: Description of performing an exemplary method according to the invention at a dynamic heating rate

[0081] The sample, containing at least one alkali metal and / or alkaline earth metal and / or related metal, is dried and placed in a measuring vessel suitable for thermal analysis, such as a DSC crucible. For unplated crucibles, excess gold foil or gold powder is added as a reactant. For gold-plated crucibles, the sample is simply placed inside. The crucible is then typically sealed and thermal analysis is performed. In DSC analysis, the crucible undergoes a temperature change procedure along with a reference crucible. For this purpose, the sample and reference are heated to a suitable temperature (e.g., 500°C) under an inert gas flow at a dynamic heating rate (e.g., 3 K / min–30 K / min).

[0082] Example 2: Description of the exemplary method according to the invention performed in an isothermal heating section

[0083] The sample, containing at least one alkali metal and / or alkaline earth metal and / or related metal, is dried and placed in a measuring vessel suitable for thermal analysis, such as a DSC crucible. For unplated crucibles, excess gold foil or gold powder is added as a reactant. For gold-plated crucibles, the sample is simply placed inside. The crucible is then typically sealed and thermal analysis is performed. In DSC analysis, the sample crucible and reference crucible are heated together to a suitable temperature, followed by isothermal heating of both. The temperature of the isothermal heating section is selected such that the exothermic reaction between gold and at least one alkali metal and / or alkaline earth metal and / or related metal is sufficiently rapid. Measurements are performed under an inert gas flow.

[0084] Example 3: Determination of lithium content in cathode material using an exemplary method according to the present invention.

[0085] Sample preparation of lithium-containing cathode materials is performed under protective gas conditions. For example, the secondary battery is first disassembled into its components, and then the lithium-containing cathode material (with or without a carrier material) is cleaned with a suitable solvent. The solvent is then removed, and a certain amount of the dried lithium-containing cathode material is transferred to a crucible. For unplated crucibles, excess gold foil or gold powder is added as a reactant. For gold-plated crucibles, only the cathode material is used. The crucible is then sealed and DSC analysis is performed. The crucible undergoes a temperature change procedure along with a reference crucible. For this purpose, the sample and reference are heated to a suitable temperature (e.g., 500°C) at a dynamic heating rate (e.g., 3 K / min–30 K / min) under an inert gas flow.

[0086] Evaluate

[0087] To determine the lithium concentration in the cathode material, a suitable amount of pure lithium (calibration sample) was used in the crucible material of the selected sample measurement (coated with gold or with added gold foil or gold powder, calibration 1), and in the same crucible without gold foil, gold powder, or without gold coating (calibration 2), using the same measurement parameters as the sample measurement. The measurement signal was then preferably evaluated by integration, with the evaluation range being the temperature range of the detected exothermic gold-lithium reaction. The heat of reaction generated by the formation of the gold-lithium alloy was obtained by subtracting the integrated value of calibration 2 from the value of calibration 1 (Au-Li reference). Subsequently, a similar integration was performed on the measurement signal of the exothermic gold-lithium reaction in the sample measurement, and the generated heat of reaction (Au-Li sample) was determined according to the reference. The lithium content participating in the reaction in the cathode material was obtained by dividing the Au-Li sample by the Au-Li reference and multiplying this ratio by the weight of calibration measurement 1.

[0088] Example 4: The Influence of Gold

[0089] Using lithium foil (weighing: 0.7 mg) as a sample, the method described in Example 1 was performed in a gold-plated stainless steel crucible; simultaneously, using lithium foil (weighing: 0.4 mg) as a sample, it was placed together with gold foil in the stainless steel crucible to perform the method described in Example 1. Furthermore, the method described in Example 1 was also performed to measure only lithium foil (weighing: 2 mg) without added gold in the stainless steel crucible. The results are as follows... Figure 2 As shown. Here, the dashed line represents the measurement result of lithium foil in a gold-plated stainless steel crucible, the dotted line represents the measurement result of lithium foil and gold foil together, and the solid line represents the measurement result without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min).

[0090] In the presence of gold, a clear measurement signal can be observed, which can be attributed to the exothermic reaction between gold and lithium. The integral values ​​of the measurement signal are represented by the shaded area, and are: 7663 au (arbitrary unit) (lithium foil in a gold-plated crucible), 1874 au (lithium foil and gold foil in a stainless steel crucible), and 263 au (lithium foil in a stainless steel crucible).

[0091] Example 5: Determination of the state of charge of electrode materials

[0092] Since the lithium content of the electrode material depends on the state of charge (SOC), the SOC can be determined by the lithium content in the electrode material. LiCoO2 was used as the electrode material, and the method described in Example 3 was performed. Furthermore, in the absence of gold, LiCoO2 was used as the electrode material, and the method described in Example 3 was performed. Lithium foil was used as the calibration sample. The measurement results and parameters are shown in Table 1.

[0093] Table 1: Measurement results of an exemplary method for determining the state of charge in electrode materials

[0094] Based on the results in Table 1, the lithium content in LiCoO2 can be determined to be 0.06 mg.

[0095] Example 6: The effect of sample drying

[0096] Using lithium manganese oxide as the sample, the method described in Example 3 was performed in a gold-plated stainless steel crucible. Here, one measurement was performed after the sample was dried, and another measurement was performed while the sample was still wet. The results are as follows... Figure 3 As shown. The dashed line represents the measurement results for the undried sample, and the solid line represents the measurement results for the dried sample. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). Sample weight: 9.9 mg for dried sample; 10.1 mg for undried sample. The integral values ​​of the measurement signal are expressed by the shaded area, which are: 766.6 au (undried sample) and 257 au (dried sample).

[0097] Comparing the measurement data of dried and undried samples reveals a superposition effect of the solvent. Here, the signal change is significantly greater than the signal change observed in the gold-lithium reaction of the dried sample.

[0098] Example 7: Determination of Sodium

[0099] Using elemental sodium (weighed: 1.7 mg) as a sample, the method described in Example 1 was performed in a gold-plated stainless steel crucible. Additionally, the method described in Example 1 was also performed, but only for elemental sodium (weighed: 2.2 mg) without added gold, measured in a stainless steel crucible. The results are as follows: Figure 4 As shown. Here, the dashed line represents the sodium measurement result in a gold-plated stainless steel crucible, and the solid line represents the sodium measurement without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min).

[0100] A distinct measurement signal can be observed in the presence of gold, which can be attributed to the exothermic reaction between gold and sodium. The integral values ​​of the measurement signal, represented by the shaded area, are 4963 au (sodium in a gold-plated crucible) and 1648 a.u. (sodium in a stainless steel crucible).

[0101] Example 8: Determination of Potassium

[0102] Using elemental potassium (weighed: 1.1 mg) as a sample, the method described in Example 1 was performed in a gold-plated stainless steel crucible. Additionally, the method described in Example 1 was also performed, but only for elemental potassium (weighed: 0.4 mg) without added gold, measured in a stainless steel crucible. The results are as follows... Figure 5 As shown. Here, the dashed line represents the potassium measurement result in a gold-plated stainless steel crucible, and the solid line represents the potassium measurement result without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min).

[0103] A distinct measurement signal can be observed in the presence of gold, which can be attributed to the exothermic reaction between gold and potassium. The integral values ​​of the measurement signal are represented by shaded areas: 1702 arbitrary units (potassium in a gold-plated crucible) and 1226 arbitrary units (potassium in a stainless steel crucible).

[0104] Example 9: Determination of calcium

[0105] Using elemental calcium (weighed: 1.3 mg) as a sample, the method described in Example 1 was performed in a gold-plated stainless steel crucible. The results are as follows: Figure 6 As shown. Measurement parameters: Instrument: Netzsch STA 449 F3 Jupiter; Heating rate: 10 K / min; Atmosphere: Nitrogen (70 ml / min).

[0106] A distinct measurement signal can be observed in the presence of gold, which can be attributed to the exothermic reaction between gold and calcium. The integral value of the measurement signal, represented by the shaded area, is 1278 au.

[0107] Example 10: Determination of lithium using an isothermal heating section

[0108] Using lithium foil (weighed 6.0 mg) as a sample, the method described in Example 2 was performed in a gold-plated stainless steel crucible. Additionally, the same measurements were performed without the sample as a reference. The results are as follows: Figure 7As shown, the measurement results are displayed at the top, and the temperature change program used is shown at the bottom. Measurement parameters: Netzsch DSC 204 F1 Phoenix; heating rate to 225°C: 30 K / min; isothermal for 1 hour; atmosphere: nitrogen (20 ml / min).

[0109] Similarly, a distinct measurement signal can be observed in the presence of gold, which can be attributed to the exothermic reaction between gold and lithium. The integral value of the measurement signal, represented by the shaded area, is 2690 au. The integral value of the reference result is 235 a.u.

[0110] Example 11: Measurement using lithium manganese oxide with a SOC of 100 as the cathode material

[0111] Lithium manganese oxide (SOC 100, weighing: 9.9 mg) was used as a sample, and the method described in Example 3 was performed in a gold-plated stainless steel crucible. Additionally, the method described in Example 3 was also performed, but only lithium manganese oxide (SOC 100, weighing: 14 mg) without gold was measured in a stainless steel crucible. The results are as follows... Figure 8 As shown. Here, the dashed line represents the measurement result of lithium manganese oxide (SOC 100) in a gold-plated stainless steel crucible, and the solid line represents the measurement result of lithium manganese oxide (SOC 100) without gold. Measurement parameters: Instrument: Netzsch DSC 204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integrated values ​​of the measurement signal are represented by the shaded areas: 257 au (with gold) and 207 au (without gold).

[0112] It can be seen that the use of gold can significantly enhance the signal, which can be attributed to the gold-lithium reaction.

[0113] Example 12: Measurement using lithium manganese oxide with different SOCs as cathode materials

[0114] Lithium manganese oxide with a SOC of 100 (weighed: 9.9 mg) and lithium manganese oxide with a SOC of 50 (weighed: 6.3 mg) were used as samples, and the method described in Example 3 was performed in a gold-plated stainless steel crucible. The results are as follows: Figure 9 As shown. Here, the dashed line represents the measurement of lithium manganese oxide with a SOC of 100, and the solid line represents the measurement of lithium manganese oxide with a SOC of 50. Measurement parameters: Instrument: Netzsch DSC204 F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integral values ​​of the measurement signal are represented by the shaded area, which are 257 au (SOC of 100) and 381 au (SOC of 50), respectively.

[0115] By comparing the obtained measurement signals, it can be seen that the integral values ​​differ significantly with different states of charge (SOC). Therefore, the state of charge of the electrode material can be inferred using the method according to the present invention.

[0116] Example 13: Measurement using lithium cobalt oxide with a SOC of 100 as the cathode material

[0117] Lithium cobalt oxide with a SOC of 100 (weighed: 12 mg) was used as a sample, and the method described in Example 3 was performed in a gold-plated stainless steel crucible. Additionally, the method described in Example 3 was also performed, but only lithium cobalt oxide with a SOC of 100 without gold addition (weighed: 7.3 mg) was measured in a stainless steel crucible. The results are as follows... Figure 10 As shown. Here, the dashed line represents the measurement results of lithium cobalt oxide (SOC 100) in a gold-plated stainless steel crucible, and the solid line represents the measurement results of lithium cobalt oxide (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 signal are represented by the shaded areas: 412 au (with gold) and 384 au (without gold).

[0118] It can be seen that the use of gold can significantly enhance the signal, which can be attributed to the gold-lithium reaction.

[0119] Example 14: Measurement using lithium cobalt oxide with different SOCs as cathode materials

[0120] Lithium cobalt oxide with a SOC of 100 (weighed: 12.0 mg) and lithium cobalt oxide with a SOC of 0 (weighed: 10.3 mg) were used as samples, and the method described in Example 3 was performed in a gold-plated stainless steel crucible. The results are as follows: Figure 11 As shown. The dashed line represents the measurement of lithium cobalt oxide with a SOC of 100, and the solid line represents the measurement of lithium cobalt oxide with a SOC of 0. Measurement parameters: Instrument: Netzsch DSC 204F1 Phoenix; Heating rate: 10 K / min; Atmosphere: Nitrogen (20 ml / min). The integral values ​​of the measurement signal are represented by the shaded area, which are 469 au (SOC of 100) and 270 au (SOC of 50), respectively.

[0121] By comparing the obtained measurement signals, it can be seen that the integral values ​​differ significantly with different states of charge (SOC). Therefore, the state of charge of the electrode material can be inferred using the method according to the present invention.

[0122] Example 15: Measurement of lithium at different heating rates

[0123] 15A: Execute the method described in Example 4 using the following parameters: The film weighed 7.8 mg in the gold-plated crucible and 5.5 mg in the unplated crucible. A Netzsch DSC 204 F1 Phoenix was used as the measuring instrument, with a heating rate of 3 K / min and a nitrogen atmosphere of 20 ml / min. The results are as follows. Figure 12 As shown. The dashed line represents the measurement signal of lithium foil in a stainless steel crucible. The solid line represents the measurement signal of lithium foil in an unplated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal. The illustration clearly shows the difference in the measurement signals.

[0124] 15A: Execute the method described in Example 4 using the following parameters: The film weighed 3.3 mg in the gold-plated crucible and 6.0 mg in the unplated crucible. A Netzsch DSC 204 F1 Phoenix was used as the measuring instrument, with a heating rate of 30 K / min and a nitrogen atmosphere of 20 ml / min. The results are as follows. Figure 13 As shown in the diagram. The dashed line represents the measurement signal of lithium foil in a stainless steel crucible. The solid line represents the measurement signal of lithium foil in an unplated stainless steel crucible. The shaded area below the lines represents the integral of the exothermic signal. The diagram also clearly shows the differences in the measurement signals.

Claims

1. A method for thermal analysis to determine alkali metals and / or alkaline earth metals and / or related metals, comprising: Provide a sample containing at least one alkali metal and / or alkaline earth metal and / or related metals; Thermal analysis measurements were performed on the sample; The sample comes into contact with gold during the thermal analysis measurement, and The sample contains virtually no solvent.

2. The method according to claim 1, wherein, The sample is dried before the thermal analysis measurement is performed.

3. The method according to claim 1 or 2, wherein, During the thermal analysis measurement, at least a portion of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample, which contains at least one alkali metal and / or alkaline earth metal and / or related metal, reacts with at least a portion of gold.

4. The method according to any one of the preceding claims, wherein, The thermal analysis measurement is calorimetry and / or differential calorimetry, particularly the thermal analysis measurement is dynamic differential calorimetry.

5. The method according to any one of the preceding claims, wherein, The thermal analysis measurement includes performing a temperature change procedure, wherein the temperature change procedure includes heating the sample from a first temperature to a second temperature at a heating rate, wherein the second temperature is at most 1000°C, optionally wherein the heating rate is from 3 K / min to 30 K / min, and / or wherein the temperature change procedure includes 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 minutes.

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

7. The method according to any one of the preceding claims, wherein, The sample is loaded into a measuring container before the thermal analysis measurement, and the sample is measured in the measuring container.

8. The method according to claim 7, wherein, The measuring container contains gold, and / or the sample is mixed with gold before being placed in the measuring container, and the sample is placed in the measuring container together with the gold.

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

10. The method according to any one of the preceding claims, wherein, The sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is at least a portion of an electrode and / or an electrode material.

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

12. Use of gold in the thermal analysis for the determination of alkali metals and / or alkaline earth metals and / or related metals in samples containing at least one alkali metal and / or alkaline earth metal and / or related metals. The sample in question is essentially solvent-free, and The sample is in contact with gold during the thermal analysis measurement process.

13. The use as described in claim 12, wherein, The sample containing at least one alkali metal and / or alkaline earth metal and / or related metal is at least a portion of an electrode and / or an electrode material.

14. The use according to claim 12 or 13, wherein, During the thermal analysis measurement, at least a portion of at least one alkali metal and / or alkaline earth metal and / or related metal in the sample, which contains at least one alkali metal and / or alkaline earth metal and / or related metal, reacts with at least a portion of gold.

15. The use according to any one of claims 12 to 14, wherein, The thermal analysis measurement is calorimetry and / or differential calorimetry, particularly the thermal analysis measurement is dynamic differential calorimetry.

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