Device for clamping and controlling the temperature of planar samples for x-ray diffractometry

Abstract

The invention relates to an apparatus (1) for clamping flat samples (6), in particular pouch battery cells, for x-ray diffractometry, wherein the apparatus has a housing (2) having a sample holder (4), which has holding elements (5) that are able to be tensioned in relation to one another for clamping the sample (6), at least two x-ray windows (11a, 11b, 12) for letting in and out x-rays, and at least one first temperature control device (7) for controlling the temperature of the sample (6). At least one first temperature control device (7) is in each case attached to the holding elements (5), wherein the first temperature control devices (7) are thermally coupled to the housing (2), and the apparatus has at least one second temperature control device (9), which is configured to dissipate heat, which is output by the first temperature control device (7) to the housing (2), out of the housing (3) to the outside and/or to introduce heat from the outside into the housing (2).

Claims

1. An apparatus for clamping flat samples, in particular pouch battery cells, for x-ray diffractometry, with the apparatus having a housing having a sample holder, which has holding elements for clamping the sample, wherein cutouts for guiding through the x-ray beam are provided in each case in the holding elements, at least two x-ray windows for letting in and out x-rays, and at least one first temperature control device for controlling the temperature of the sample, with the first temperature control device being thermally coupled to the housing, and with the apparatus having at least one second temperature control device, which is configured to dissipate heat, which is output by the first temperature control device to the housing, out of the housing to the outside and/or to introduce heat from the outside into the housing, wherein the holding elements have a plate-shaped configuration and contact surfaces that face one another for clamping the sample, with in each case at least one first temperature control device being attached to the side of the holding element that faces away from the respective contact surface, and with a spring mechanism being provided for the tensioning of the holding elements in relation to one another.

2. The apparatus as claimed in claim 1, wherein the holding elements are designed in the form of plates that are arranged in parallel.

3. The apparatus as claimed in claim 1, wherein the sample holder is fastened in the housing using heat decoupling elements.

4. The apparatus as claimed in claim 1, wherein the second temperature control device comprises active and/or passive means for supplying and/or dissipating heat out of and/or into the housing wall.

5. The apparatus as claimed in claim 1, further comprising a temperature monitoring device, which is operatively connected to the first and/or the second temperature control devices and is configured to set a temperature of the sample by open-loop or closed-loop control of the first and/or second temperature control device.

6. The apparatus as claimed in claim 5, wherein a) the second temperature control device comprises means for active and/or passive air temperature control and the temperature monitoring device is configured such that the closed-loop control of the temperature of the sample can be realized by the closed-loop control of the energy supply of the first temperature control device; and/or b) the second temperature control device comprises liquid temperature control, and the temperature monitoring device is configured such that the closed-loop control of the temperature of the sample can be realized by the closed-loop control of the temperature of the temperature control liquid, with the first temperature control device being preferably operated with constant voltage.

7. The apparatus as claimed in claim 1, wherein a plurality of second temperature control devices is provided on and/or in the housing wall, with at least one second temperature control device being arranged in each case in the thermal coupling region between a first temperature control device and the housing.

8. The apparatus as claimed in claim 1, wherein the first temperature control device comprises at least one Peltier element.

9. The apparatus as claimed in claim 8, wherein the first temperature control device comprises a plurality of Peltier elements being connected in series.

10. The apparatus as claimed in claim 1, wherein the housing is able to be hermetically sealed with respect to the environment and has at least one connection for introducing working gas into the housing.

11. The apparatus as claimed in claim 1, wherein it is configured such that the temperature control devices operate without cryogenic refrigerants.

12. A pouch battery cell clamped by the apparatus as claimed in claim 1, for x-ray diffractometry.

Description

DESCRIPTION OF THE FIGURES

(1) The present invention will be explained in more detail below with reference to merely preferred exemplary embodiments and the drawings. In the figures:

(2) FIGS. 1a,b depict an apparatus according to a first embodiment of the invention;

(3) FIG. 2 depicts a schematic illustration of the apparatus from FIG. 1 in a sectional exploded view;

(4) FIG. 3 depicts holding elements and first temperature control devices in the form of cascaded Peltier elements of the apparatus from FIG. 1;

(5) FIG. 4 depicts components of the apparatus from FIG. 1;

(6) FIG. 5 depicts a sectional view of the apparatus from FIG. 1;

(7) FIG. 6 schematically illustrates the flow of energy of the apparatus from FIG. 1;

(8) FIG. 7 schematically illustrates an apparatus according to a further embodiment of the invention in a sectional view;

(9) FIG. 8 depicts a housing part of the apparatus from FIG. 7 with introduced cooling liquid duct;

(10) FIG. 9 schematically illustrates the passage of the x-ray radiation through the apparatus from FIG. 7;

(11) FIG. 10 shows the apparatus from FIG. 7 with a hermetic housing seal and a linear stage for sample alignment;

(12) FIG. 11 schematically illustrates the control loop for controlling the temperature of a sample in the apparatus from FIG. 1; and

(13) FIG. 12 schematically illustrates the control loop for controlling the temperature of a sample in the apparatus from FIG. 7.

(14) FIGS. 1 to 6 show the setup and, schematically, the operation of an apparatus according to the invention in accordance with a first embodiment of the invention on the basis of different illustrations. FIG. 2 here schematically shows the arrangement of the components in a sectional view of an exploded illustration. FIG. 6 schematically shows the heat exchange during operation of the apparatus. The heat exchange is marked by way of arrows.

(15) The apparatus 1 for x-ray examinations that is illustrated in FIGS. 1a, 1b serves for controlling the temperature of flat samples. To allow the view of the internal structure, a hermetic enclosure, which the apparatus otherwise has, was omitted. The apparatus 1 comprises a housing 2, of which here only two front and rear walls 3 of the housing are illustrated. A sample holder 4 is arranged in the interior of the housing 2. Said sample holder 4 comprises two plate-type holding elements 5 for holding a flat sample 6 that is arranged therebetween, as is shown in the sectional view in an exploded illustration in FIG. 2. In the case of a lithium-ion battery, said battery is present in the form of what is known as a pouch cell. The pouch-bag structural form makes it possible for the outer sides of the pouch cell to press flat against the contact surfaces of the plate-type holding elements 5 that face one another, so that a large heat transfer surface is ensured.

(16) The plate-type holding elements 5 consist of aluminum and have a high thermal conductivity. Due to the direct contact with the pouch cell, they are thermally coupled thereto. First temperature control devices 7 in the form of cascaded Peltier elements are attached to the side of the holding elements 5 that face away from the contact surface and are in direct heat transfer contact with the holding elements. FIG. 3 in this regard shows how one of the first temperature control devices is mounted on one of the two sample holding elements 5. Depressions in the holding elements 5 serve to accommodate the Peltier elements 7 and to minimize the remaining wall thickness of the holding element for a good heat transfer to the sample.

(17) As is evident in the schematic view in FIG. 2, the holding elements 5 can be tensioned in relation to one another via tensioning elements, such as springs, to hold the sample 6 between them. FIGS. 1 and 5 illustrate these tensioning elements in the form of spring pre-tensioned screws 13, which are guided in the outer housing.

(18) On the outer side of the housing 2 (FIGS. 1a, 1b, 2, 5), second temperature control devices 9 in the form of combined fan/cooling rib units for dissipating heat out of the housing wall 3 are attached in front of the first temperature control devices 7 in a direction proceeding from the housing wall 3 in the direction of the sample 6 or the sample holder 4. These second temperature control devices 9 are in each case placed in the thermal coupling region between a first temperature control device 7 and the housing wall 3. Except for the first temperature control devices 7, the sample holder 4 is thermally decoupled from the housing wall 3 and is to this end fastened in the housing via screws guided in ceramic sleeves 10a and via ceramic washers 10b. The direct heat transfer from the battery to the housing thus primarily takes place via the first temperature control devices 7.

(19) As is evident from FIG. 4, the Peltier elements 7 are thermally coupled on the side of the first temperature control devices that faces away from the holding elements 5 to the second temperature control device 9 to ensure a high degree of heat transfer. In principle, the Peltier element can be placed directly on the inner housing wall 3, and the second temperature control device 9 can be placed on the outside of the housing. In the present case, however, the housing comprises a heat transfer element 8, which is placed into an opening or a window in the housing wall 3 and ensures improved heat transfer between the first and second temperature control devices 7, 9, since the heat transfer element 8 is in contact with the first temperature control device 7 on the housing inside and with the second temperature control device 9 on the housing outside.

(20) FIG. 5 shows the placement of the second temperature control devices 9 directly opposite the first temperature control devices 7.

(21) In a central section of the housing 2, x-ray windows 11a, 11b are formed on opposite sides of the housing wall 3 (FIGS. 1a, 1b, and 2). These x-ray windows are used for guiding through an x-ray beam, which penetrates through the first x-ray window 11a into the housing 2, penetrates through the sample 6, and exits from the larger second x-ray window 11b to subsequently be incident on a detector. For guiding the x-ray beam through the holding elements 5, the latter have through-cutouts 12a and 12b in a central section.

(22) The holding elements 5 and the inner housing wall 3 and also the mutually opposing housing walls 3 are connected to one another via tensioning elements 13 in the form of spring pre-tensioned screws (see FIG. 5). The Peltier elements are pressed on the housing wall in the direction of the sample by the spring force tensioning force of the tensioning elements (spring elements) 13. By energizing the Peltier elements, a temperature difference arises between two sides of the Peltier element which can be effectively used for cooling or heating the sample or the holding element. In the setup shown here, the Peltier elements are in contact, by way of their cold side, with the holding elements. Electrical connections of a battery as the sample 6 are guided in a sealed state out of the housing 2 and connected to a bipotentiostat 14 (FIG. 2) to charge or discharge the battery. Electrical connections for energizing the Peltier elements are also guided in a sealed state out of the housing, but are not shown.

(23) A polyamide film, which has a high thermal stability and a high transmissivity for x-rays (for example, Kapton film) is adhesively bonded over the x-ray windows 11a, 11b and the cutouts 12a, 12b.

(24) The housing 2 is hermetically sealed with respect to the environment but also has additional connections 15 (FIG. 2) for supplying or discharging working gas, such as a nitrogen flush. The inner space of the housing 3 can thus be flushed with nitrogen gas to prevent the formation of condensed water and/or ice at low temperatures.

(25) By energizing the Peltier elements, they cool the holding elements and transfer the absorbed heat on the other side of the Peltier element to the housing wall. The cooling of the housing wall by means of the second temperature control device has the result that the efficiency of the Peltier element also increases.

(26) FIG. 6 schematically shows the transport of thermal energy in the form of arrows from/to the sample 6 via the holding plates 5 and first temperature control device 7 from/to the outer housing 2 and here via the second temperature control device 9 to the environment outside.

(27) The further embodiment shown in FIGS. 7 to 10 differs from the first embodiment in that the second temperature control device 9 is designed in the form of a liquid temperature control device. To this end, temperature control liquid ducts 16 are installed in the housing wall 3 (see FIG. 8). In principle, however, these can also be attached in the form of lines to the outside of the housing 3. The second temperature control devices 9 are connected to a common cooling liquid circuit (not illustrated). FIG. 10 depicts this embodiment in a closed form having a hermetic side cover 26 and an attached linear drive 25 for aligning the entire apparatus including the sample in the x-direction with respect to the x-ray beam. This alignment device is utilizable for both described embodiments.

(28) FIG. 9 schematically illustrates an examination setup for an x-ray diffractometry analysis of a flat sample. For this purpose, the apparatus 1 is mounted in an x-ray diffractometer between x-ray beam emitter (x-ray tube) and a detector.

(29) As is illustrated in FIG. 9, the x-rays are emitted by an x-ray tube 17 and are incident on a focusing x-ray optical unit 18. After deflection of the x-ray beam, it penetrates the housing 2 via the first x-ray window 11a, penetrates through the first cutout 12a and subsequently the sample 6. The crystal atoms in the sample cause incident x-rays to be diffracted into different, characterizing directions. After penetrating through the sample, the x-ray beams exit the holding elements through the second cutout 12b, leave the housing through the second x-ray window 11b, and are incident on a detector 24 to produce a diffraction pattern.

(30) The x-ray light that is scattered in the sample and exits at the angle 2 is detected on the output side in the detector 24 by way of a sensor that is sensitive to x-ray light. In a (one-dimensional) diffractogram, the measured radiation intensities are plotted over the angle between radiation source, sample, and detector (2 angle). The sample itself is not moved during the measurement. In the case of batteries as the sample, the scattering peaks in the diffractogram, which originate from the passive components installed in the battery, such as a copper anode or aluminum enclosure, are used to correctly align the battery in the beam direction. To this end, the apparatus 1 mounted on a linear stage 25 is moved with the mounted battery in the longitudinal direction until said reference peaks are located at the theoretically correct position.

(31) Subsequently, various operating variants can be examined, wherein the first and second temperature control devices maintain the temperature of the sample at a predetermined and constant level.

(32) FIG. 11 schematically illustrates the control loop for an air-cooled design in the temperature control of the sample 6. The control loop is part of a temperature monitoring device, which is operatively connected to the first temperature control devices 7 and is configured to set a temperature of the sample 6 to a TARGET value by closed-loop control of the first temperature control devices 7 (Peltier elements).

(33) A temperature sensor 19, which is connected to the sample 6, measures the temperature of the sample 6. The temperature signal (measurement element) is fed back as an ACTUAL signal to a temperature regulator, which controls a regulatable power supply unit 21 as an actuator, which supplies the first temperature control devices 7 with voltage, taking into account the TARGET temperature. By reversing the polarity of the Peltier elements, the latter can be switched to heating operation.

(34) FIG. 12 schematically illustrates the control loop for a liquid-cooled design for controlling the temperature of the sample 6. Here too, the control loop is part of a temperature monitoring device, which is operatively connected to the second temperature control devices 9 in the form of liquid cooling (see FIG. 7) and is configured to set a temperature of the sample 6 to a TARGET value by closed-loop control of the second temperature control device 9. The closed-loop control is realized by setting the flow temperature of the cooling water.

(35) A temperature sensor 19, which is connected to the sample 6, measures the temperature of the sample 6. The temperature signal (measurement element) is fed back as an ACTUAL signal to a temperature regulator 20, which controls the cooling water supply (actuator) 22 taking into account the TARGET temperature. The power supply unit 21 is supplied with constant voltage. The first temperature control devices 7 are installed in a series connection and are operated with constant power. In principle, the second temperature control device shown in FIG. 12 can also be switched over to heating operation.

LIST OF REFERENCE SIGNS

(36) 1 Apparatus for x-ray examinations

(37) 2 Housing

(38) 3 Housing wall

(39) 4 Sample holder

(40) 5 Holding element

(41) 6 Sample (lithium-ion rechargeable battery)

(42) 7 First temperature control device

(43) 8 Heat transfer element

(44) 9 Second temperature control device

(45) 10a Ceramic sleeve

(46) 10b Ceramic washer

(47) 11a,b X-ray window

(48) 12a,b Cutout

(49) 13 Tensioning elements

(50) 14 Bipotentiostat

(51) 15 Working gas connection

(52) 16 Temperature control liquid duct

(53) 17 X-ray tube

(54) 18 Focusing optical unit

(55) 19 Temperature sensor

(56) 20 Temperature regulator

(57) 21 Power supply unit

(58) 22 Entering x-ray beam

(59) 23 Exiting x-ray beam

(60) 24 X-ray detector

(61) 25 Linear drive

(62) 26 Hermetic housing seal