Method and system for measuring valuable substances in recycled battery materials

Abstract

The invention relates to a method and a system for detecting the element lithium and other heavy elements such as cobalt, nickel, manganese, carbon, copper and aluminum, and can be used in the at-line measurement of the components (valuable substances) of black masses, the product of recycling processes for lithium-ion batteries. The subject matter of the invention includes the qualitative and quantitative analysis of the measured spectrometric data.

Description

[0001] Methods and systems for measuring valuable materials in

[0002] Battery recycling materials

[0003] The invention relates to a method and a system for measuring valuable materials in battery recycling materials and is applicable in the at-line measurement of the components (valuable materials) of black masses, the product of lithium-ion battery recycling processes. The subject matter of the invention includes the qualitative and quantitative evaluation of the measured spectrometric data after irradiation with an electron beam source.

[0004] Sustainable, circular economy practices are one of the major challenges facing future global economic development. The climate crisis and resource scarcity necessitate closed-loop, quality-assured, and energy-efficient technological processes. In this context, process-integrated analytical methods and equipment systems are the lifeblood of a smart recycling economy. This also applies to the recovery of valuable materials such as cobalt, nickel, manganese, carbon, copper, aluminum, and lithium from the black mass recycling process of lithium-ion batteries.

[0005] The detection of the element lithium and its chemical compounds using X-ray fluorescence spectrometry has so far been impossible or only insufficiently possible.

[0006] The detection sensitivity achieved so far in the lower % range is unsatisfactory for samples consisting of a large number of different elements, such as black mass, the recycled material from Li-ion batteries.

[0007] The reasons for this are:

[0008] - the small, excited sample volume (penetration depth of electrons into the sample surface of 10 nm due to an electron energy of less than 1 keV)

[0009] - the intrinsic absorption of Li fluorescence radiation in the sample

[0010] - the small aperture of the optical system - the high scattering background and the superposition of the Li K alpha fluorescence line with higher harmonics, the fluorescence lines of elements O and C

[0011] - the bremsstrahlung background generated by excitation with electrons.

[0012] The instrument technology of the present solution according to the invention is based on wavelength-dispersive X-ray fluorescence hybrid reflection zone plate / multilayer spectrometers for the soft X-ray range, wherein individual components of the instrument technology are known from the prior art.

[0013] DE 10 2012 013 530 B3 describes the use of reflection zone plates as dispersive elements.

[0014] EP 0 999 555 B1 discloses a Soller slot arrangement and a method for its manufacture.

[0015] From EP 2 377 309 B1 a spectrally resolving electronic X-ray camera is known in which a two-dimensional pixelated semiconductor sensor is arranged as the recording element for simultaneous spatial, energy and temporal resolution.

[0016] The publication “ERKO, Alexei [et al.]: New parallel wavelength-dispersive spectrometer based on scanning electron microscope. In: Optics Express, Vol. 22, 2014, No. 14, pp. 16897-16902. - ISSN 1094-4087” describes a WDX X-ray spectrometer for conventional scanning electron microscopy using a 17-channel reflectance zone plate array for the energy range of 50 eV to 1116 eV. However, no lithium spectrum is shown, and a quantitative evaluation of the measurements is not presented.

[0017] The publication “HASSEBI, Khali [et al.]: High-resolution x-ray emission spectrometry in the lithium K range with a reflection zone plate spectrometer. In: X-ray spectrometry, 17 April 2024. DOI: 10.1002 / xrs.3427 [accessed on 25.02.2025]” presents measured and calculated spectra of lithium and lithium compounds obtained with a WDX spectrometer using a reflection zone plate. However, the composition of the samples was known, allowing the spectra to be calculated using density functional theory. A quantitative evaluation of the measurements on unknown samples was not performed. In the article “J. Probst: “Light element analysis with the parallel wavelength dispersive spectrometer WDSX-300”, 11th Symposium on Process-Oriented X-ray Analysis PRORA Program - Conference Papers, pp. 31-32, 24.11. - 25.11.At the 2022 conference in Berlin Adlershof, results from measurements on light elements such as lithium using the WDSX-300 X-ray spectrometer will be presented. This spectrometer was also used for the measurements described in the aforementioned publication, "HASSEBI, Khali [et al.]: High-resolution x-ray emission spectrometry in the lithium K range with a reflection zone plate spectrometer. In: X-ray spectrometry, 17 April 2024. DOI: ."

[0018] 10.1002 / xrs.3427 [accessed on 25.02.2025]“ presented results.

[0019] While US2024 / 0044 821 A1 describes a combination of WDX and EDX for detecting X-ray fluorescence spectra, the excitation of these spectra is limited to X-rays and gamma rays. Excitation by electrons or other charged particles is not mentioned.

[0020] Just like DE 102012 013 530 B3, DE 10 2013 207 160 A1 and DE 10 2007 048 743 A1 describe the use of reflection zone plates as dispersive elements.

[0021] The invention is based on the objective of creating a method and a system for measuring valuable materials in battery recycling materials, on the one hand for the detection of the element lithium, on the other hand the elements cobalt, nickel, manganese, carbon, copper, aluminium at-line in an industrial environment, which have a high detection sensitivity, ensure sufficient energy resolution and are characterized by high availability.

[0022] These problems according to the invention are solved by the features in claims 1 and 8.

[0023] Advantageous embodiments of the invention are contained in the dependent claims.

[0024] A significant advantage of the inventive method for measuring valuable materials in battery recycling materials from Li-ion batteries, particularly from black materials, by evaluating the X-ray fluorescence emitted and detected by samples of the recycling products after irradiation with an electron beam source, is that the high energy resolution of the hybrid reflection zone plate or multilayer as a dispersive element is methodically coupled with an energy-dispersive silicon drift chamber detector or a photodiode, with the aid of which the higher harmonics of the dispersive element of such elements as O and C are detected in the interest of high energy resolution.

[0025] The detection sensitivity of the elements to be measured is suppressed, whereby the following process steps are implemented:

[0026] - Irradiation of the samples with electrons in the range of 0.5 ... 3 keV from a line, area or point source with respective beam currents in the range > 1 mA for the detection of the element lithium, or irradiation of the samples with electrons in the energy range of 5 ... 30 keV for the detection of the elements cobalt, nickel, manganese, carbon, copper, aluminium with respective beam currents in the range > 1 pA,

[0027] - Energy resolution of X-ray fluorescence radiation with a dispersive element,

[0028] - Measurement of dispersed fluorescence radiation using a silicon drift chamber detector to minimize higher harmonics or a photodiode,

[0029] - Switching of the electron beam source from irradiating the samples with low-energy electrons in the range of 0.5 ... 3 keV for the detection of the element lithium to irradiating the samples with electrons in the energy range of 5 ... 30 keV for the detection of the elements cobalt, nickel, manganese, carbon, copper, aluminum.

[0030] A further advantage of the invention is the high energy resolution of the X-ray fluorescence radiation achieved by a reflection zone plate with a flat or curved, focusing surface, whereby the fluorescence excitation occurs in a line-like manner. It is also possible to achieve high energy resolution of the X-ray fluorescence radiation with a flat multilayer plate and to achieve large-area fluorescence excitation. The high energy resolution of the reflection zone plates allows for the measurement of shifts in the fluorescence lines along the energy axis resulting from different molecular formations.

[0031] It is also advantageous that the parallelization of the fluorescence radiation emitted by the sample is achieved with a low divergence of approximately 0.1° to 0.5° using a Soller slot arrangement, and that the identification of the maxima of the characteristic fluorescence lines is realized by means of an aperture designed as a slot aperture of adjustable width in front of the detector.

[0032] In another embodiment of the invention, the energy resolution of the X-ray fluorescence radiation is achieved using a spherically shaped multilayer and the fluorescence excitation is point-like. In this embodiment, no Soller slot arrangement is used.

[0033] A particular advantage of the invention results from an optimized device configuration, wherein the system for detecting the element lithium from recycled Li-ion battery products by evaluating the X-ray fluorescence emitted and detected by samples of the recycled products (black masses) after irradiation with low-energy electrons in the range of 0.5 ... 3 keV and high beam currents in the range > 1 mA comprises the following alternative approaches:

[0034] I. X-ray hybrid reflection zone plate spectrometer with an electron beam source for line-shaped excitation (line focus) of the fluorescence, at least one dispersive element, a Soller slot arrangement, a silicon drift chamber detector and two apertures, wherein the Soller slot arrangement is arranged in the beam path in front of the dispersive element and the first aperture is arranged in front of the Soller slot arrangement and the second aperture is arranged behind the Soller slot arrangement.

[0035] A further advantage of the invention lies in the dimensioning of the line focus, which has a size in the range of 10 pm x 10 mm. Additional advantages result from the type of wavelength-dispersive decomposition of the X-rays, in that the dispersive elements are reflection zone plates, wherein the reflection zone plates have flat or curved surfaces.

[0036] II. X-ray multilayer spectrometer with an electron beam source for large-area excitation of fluorescence, where the excited area is adapted to the aperture of the Soller slot, e.g., 15 x 15 mm². Compared to line focus, the excited sample volume increases by a factor of 2.25 x 10³. Taking into account the transmission losses at the Soller slot and the limited reflectivity of the multilayer, good overall efficiency is achieved. The achievable gain compared to the grating variant is more than 10⁵ times higher. The achievable energy resolution is 2 eV. Either a suitable photodiode or a windowless drift chamber detector can be used as a detector.

[0037] III. X-ray multilayer spectrometer in Johansson arrangement with an electron beam source for point excitation (10 microns) of the fluorescence, wherein the spherically shaped multilayer is exactly adjacent to the Rowland circle and thus the monochromatic beam (Li k alpha line) can be focused onto the detector, which is also geometrically arranged on the Rowland circle.

[0038] The large aperture of the focusing multilayer mirror and the absence of collimators, while maintaining sufficient energy resolution, allows for an improvement compared to the reflection zone plate variant.

[0039] IV. Method coupling of an X-ray hybrid reflection zone plate / multilayer spectrometer with an energy-dispersive spectrometer (EDX) in one setup.

[0040] To meet the requirements for an industrially suitable, robust, cost-effective, and always available (24 / 7) measuring device, a compact design is necessary. The inventive design contains only one electron source for fluorescence excitation, the accelerating voltage of which is switchable between 3 kV for excitation of the Li K line and 30 kV for excitation of heavier elements such as Co, Ni, Mn, C, Cu, and Al. In a single device, both Li, using a hybrid reflectance zone plate / multilayer spectrometer, and the heavier elements, using an EDX spectrometer, are measured sequentially.

[0041] The invention will be described in more detail below with reference to exemplary embodiments illustrated at least partially in the figures.

[0042] They show:

[0043] Fig. 1 Optical diagram of the X-ray hybrid reflection zone plate spectrometer

[0044] Fig. 2 Optical diagram of the X-ray multilayer spectrometer

[0045] Fig. 3 Optical scheme of the X-ray multilayer spectrometer in

[0046] Johansson order

[0047] Fig. 4 Sketch of the X-ray hybrid reflection zone plate / multilayer spectrometer (WDX) in method coupling with an EDX spectrometer in one setup

[0048] Fig. 1 shows the individual components of the system according to the invention for detecting the element lithium. Not shown in Fig. 1 is an electron beam source for irradiating the sample 1, which emits an electron beam of

[0049] It features a current of > 0.5 mA and a line focus of 10 pm x 10 mm. The cathode area is equipped with an ion getter pump to ensure the required vacuum.

[0050] Also not shown is a vacuum lock for feeding the samples 1, for example in tablet form with dimensions < 20 mm diameter.

[0051] A Soller slot arrangement 2 is positioned in the beam path of the fluorescence radiation emitted by sample 1 for parallelization.

[0052] A first aperture 3 is arranged in front of the Soller slot arrangement 2, and a second aperture 5 is arranged behind the Soller slot arrangement 2 and in front of the dispersive element 4. In the present embodiment, the dispersive element 4 is a reflective zone plate 4.1.

[0053] In the present embodiment, the silicon drift chamber detector 6 is a cooled, large-area, windowless silicon drift chamber detector. The silicon drift chamber detector 6 can be separated from the rest of the vacuum vessel by means of a vacuum slide valve.

[0054] In the vacuum vessel (not shown in Fig. 1), the dispersive element 4 and the Soller slot arrangement 2 are mounted on precise adjustment units. Precise alignment of these elements along the optical axis is required. The silicon drift chamber detector 6 is mounted on a swiveling goniometer arm to locate the respective angular position of the line maximum.

[0055] The invention provides an X-ray grating spectrometer for the energy range 40 .... 2000 eV with a high resolution of < 0.5 eV and a detection sensitivity of 100 ... 1000 ppm for the detection of the element lithium.

[0056] Fluorescence excitation is achieved with low-energy electrons (0.5 .... 3 keV) and high beam currents (> 1 mA).

[0057] The black mass samples 1 are excited linearly using a line focus of the electron beam source with, in the present embodiment, 10 pm x 10 mm.

[0058] As dispersive elements 4, reflection zone plates 4.1 are used on substrates with flat or curved surfaces. The focusing properties of the gratings can also be used, with the respective focus lying in the detector plane.

[0059] The dispersive element 4, configured as a reflection zone plate 4.2, is formed in the present embodiment from a silicon single-crystal substrate onto which Fresnel structures are deposited by electron beam Z-laser lithography. The Fresnel structures have dimensions of 10 mm x 30 mm. The surface of the plate of the dispersive element 4 consists of a 45 nm gold layer.

[0060] An increase in detection sensitivity and energy resolution is made possible by the use of gratings with curved surfaces as a dispersive element 4.

[0061] In the present embodiment, an improved hybrid reflection zone plate is used for wavelength-dispersive decomposition of the X-rays, which allows polychromatic or achromatic focusing in the dispersive direction with a high acceptance angle and enables spectrometry over a broad energy range. The curvature of the substrate ensures increased signal intensity on the silicon drift chamber detector 6 and thus an increase in the efficiency of the system.

[0062] The parallelization of the fluorescence radiation emitted by sample 1, which is required for sufficient energy resolution, is achieved using the Soller slot arrangement 2, which has a permissible divergence at the output.

[0063] In the present embodiment, the Soller slot arrangement consists of parallel foils of specific thicknesses and spacing, with surfaces exhibiting low reflectivity for soft X-rays. The divergence of the output radiation from the Soller slot arrangement 2, and thus the achievable resolution of the spectrometer, can be determined by the spacing of the foils and the length of the Soller slot.

[0064] The dispersed fluorescence radiation is measured using the silicon drift chamber detector 6, which allows for energy-dispersive recording of the spectrum and thus the suppression of higher harmonics from other interfering elements due to the properties of the lattice. This improves the conditions for optimal quantitative evaluation of the measured spectra.

[0065] The level of innovation of the invention is largely determined by the method coupling of WDX (hybrid reflection zone plates - wavelength dispersive) and EDX (SDD - energy dispersive) spectrometry.

[0066] The excellent energy resolution of the grating spectrometer makes it possible to identify molecules using X-ray fluorescence spectrometry that manifest themselves in the chemical shift of the fluorescence lines and lie in an energy range of approximately 5 eV (50 - 55 eV).

[0067] This is achieved by the linear excitation of the Li fluorescence radiation in sample 1 using a relatively high electron current in the mA range and low electron energy, the use of the Soller slot arrangement 2 to parallelize the radiation excited in sample 1 with low divergence in the interest of high energy resolution, the modification of the inner walls of the vacuum vessels to minimize unwanted background radiation and by suitable coating.

[0068] According to the invention, the samples 1 are supplied close to the process by taking representative samples 1 from the process itself, wherein the samples 1 are transported to the measuring position inside the device using suitable manipulators.

[0069] Fig. 2 shows a variant with planar excitation of X-ray fluorescence for large-area detection of lithium. Analogous to the instrument setup according to Fig. 1, a Soller slot arrangement 2 is positioned in the beam path of the fluorescence radiation emitted by sample 1 for parallelization. The Soller slot serves as a collimator, which creates the prerequisite for the function of the downstream dispersive element 4, in this embodiment a planar multilayer mirror as a wavelength separator with a moderate energy resolution of a few eV.

[0070] Here too, a first aperture 3 is arranged in front of the Soller slot arrangement 2 and a second aperture 5 is arranged behind the Soller slot arrangement 2 and in front of the dispersive element 4. Scattered radiation is shielded by the apertures 3 and 5 at the inlet and outlet apertures, so that only the nearly parallel radiation reflected by the multilayer 4.2 reaches the detector 6.

[0071] This embodiment is based on the idea of ​​parallel processing of numerous point sources distributed in a surface element using a common optic ("multiplex method").

[0072] Fig. 3 shows a variant with point-like excitation of X-ray fluorescence for the detection of lithium. In contrast to the embodiments shown in Figures 1 and 2, this embodiment has no apertures or Soller slot arrangement. The reflection of LiKa occurs at a spherically curved multilayer 4.3 in the Rowland geometry. The partially focused radiation is detected by the detector 6. Fig. 4 shows a sketch of an X-ray hybrid reflection zone plate / multilayer spectrometer (WDX) coupled with an EDX spectrometer in a single setup.

[0073] The power supply 7 provides energy to the electron beam source 8, enabling the generation of either electron radiation in the energy range of 0.5 to 3 keV for the detection of lithium, or electron radiation in the energy range of 5 to 30 keV for the detection of cobalt, nickel, manganese, carbon, copper, or aluminum. The X-ray fluorescence radiation from irradiation with accelerating voltages up to 3 kV is directed to the WDX spectrometer via a dispersive element 4, while the X-ray fluorescence radiation from irradiation with accelerating voltages up to 30 kV is directed to the EDX spectrometer.

[0074] The invention is not limited to the embodiments presented here. Rather, it is possible to realize further solution variants by combining and varying the named means and features without departing from the scope of the invention.

[0075] Reference symbol list

[0076] 1 sample

[0077] 2 Soller slot arrangement

[0078] 3 first aperture

[0079] 4 dispersive element

[0080] 4.1 Reflection zone plate

[0081] 4.2 flat multilayer

[0082] 4.3 Spherically curved multilayer

[0083] 5 second aperture

[0084] 6 Detector, photodiode

[0085] 7 Power supply

[0086] 8 Electron beam source

Claims

Patent claims 1. Method for measuring valuable materials in battery recycling materials (black masses) by evaluating the X-ray fluorescence radiation emitted and recorded by samples of the recycling products after irradiation from an electron beam source, comprising the following process steps: - Irradiation of the samples with electrons in the range of 0.5 ... 3 keV from a line, area or point source with respective beam currents in the range > 1 mA for the detection of the element lithium, or irradiation of the samples with electrons in the energy range of 5 ... 30 keV for the detection of the elements cobalt, nickel, manganese, carbon, copper, aluminium with respective beam currents in the range > 1 pA, - Energy resolution of X-ray fluorescence radiation with a dispersive element, - Measurement of dispersed fluorescence radiation using a silicon drift chamber detector to minimize higher harmonics or with a photodiode, - Switching of the electron beam source from irradiating the samples with electrons in the energy range of 0.5 ... 3 keV for the detection of the element lithium to irradiating the samples with electrons in the energy range of 5 ... 30 keV for the detection of the elements cobalt, nickel, manganese, carbon, copper, aluminium.

2. Method according to claim 1, characterized in that the energy resolution of the X-ray fluorescence radiation is achieved with a reflection zone plate having a flat or curved and focusing surface and the fluorescence excitation is linear.

3. Method according to claim 1, characterized in that the energy resolution of the X-ray fluorescence radiation is achieved with a planar multilayer and the fluorescence excitation is carried out over a large area.

4. Method according to claim 2 or 3, characterized in that the parallelization of the fluorescence radiation emitted by the sample is carried out using a Soller slot arrangement with a low divergence of approximately 0.1° to 0.5°.

5. Method according to claim 2 or 3, characterized in that the identification of the maxima of the characteristic fluorescence lines is carried out in front of the detector by means of an aperture designed as a slit aperture of adjustable width.

6. Method according to one of the preceding claims, characterized in that the silicon drift chamber detector suppresses the higher harmonics of the reflection zone plates of elements such as 0 and C in the interest of high detection sensitivity of the elements being measured and / or that the high energy resolution of the reflection zone plates allows shifts of the fluorescence lines on the energy axis as a result of different molecular formations to be measured.

7. Method according to claim 1 characterized in that the energy resolution of the X-ray fluorescence radiation is achieved with a spherically shaped multilayer and the fluorescence excitation is performed in a point-like manner.

8. System for measuring valuable materials in battery recycling materials (black masses) by evaluating samples (1) of the battery recycling products after irradiation with electrons in the energy range of 0.5 .... 3 keV from a line, area or point source or irradiation with electrons in the energy range of 5... 30 keV with beam currents in the range > 1 pA, excited, emitted and detected X-ray fluorescence radiation comprising an electron beam source with line, point or area excitation of the X-ray fluorescence at least one dispersive element (4) a silicon drift chamber detector or a photodiode (6).

9. System according to claim 8, characterized in that the dispersive elements (4) are reflection zone plates (4.1 ).

10. System according to claim 9, characterized in that the reflection zone plates (4.2) have flat or curved surfaces.

11. System according to claim 8, characterized in that the dispersive element is a planar multilayer (4.2).

12. System according to one of claims 8 - 12, characterized in that a Soller slot arrangement (2) and two apertures (3, 5) are arranged and the Soller slot arrangement (2) is arranged in the beam path in front of the dispersive element (4) and the first aperture (3) is arranged in front of the Soller slot arrangement (2) and the second aperture (5) is arranged behind the Soller slot arrangement (2).

13. System according to claim 8, characterized in that the dispersive element is a spherically curved multilayer (4.3).

14. System according to claim 8, characterized in that the electron beam source is switchable such that the accelerating voltage is switchable between 1 kV for the excitation of the Li K line and 30 kV for the excitation of the heavy elements, such as cobalt, nickel, manganese, carbon, copper or aluminium, whereby in a single device both the Li using the hybrid reflection zone plate / multilayer spectrometer and the heavy elements using an EDX spectrometer are sequentially measured.

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