Method and arrangement for inline gas analysis measurements in a formation process for secondary cells

Abstract

The present disclosure generally pertains to production of rechargeable battery cells, commonly called secondary cells. More specifically, the disclosure relates to inline gas analysis measurements in a formation process for secondary cells. According to a first aspect the disclosure relates to an arrangement 2 for inline gas analysis measurements in a formation process for secondary cells 1. The arrangement 1 comprises a gas analysis container 22, a plug extraction mechanism 21, and a gas analyser 27. The gas analysis container comprising a sample inlet 23 designed to form fluid tight connection to an opening 12 of a secondary cell 1 to be tested, and an outlet 26. The plug extraction mechanism designed to pull a plug 11 arranged to seal the opening 12, while the opening 12 is connected to the sample inlet 23 of the gas analysis container 22, whereby formation gas residing inside the analysis container 22 is exhausted through the opening 12 and flows into the gas analysis container 22. The gas analyser 27 arranged to be connected to the outlet 26 of the gas analysis container, whereby gas spectra of the formation gas in the analysis container can be analysed. The disclosure also pertains to a corresponding method.

Description

[0001] METHOD AND ARRANGEMENT FOR INLINE GAS ANALYSIS MEASUREMENTS IN A FORMATION PROCESS FOR SECONDARY CELLS

[0002] TECHNICAL FIELD

[0003] The present disclosure generally pertains to production of rechargeable battery cells, commonly called secondary cells. More specifically, the disclosure relates to inline gas analysis measurements in a formation process for secondary cells.

[0004] BACKGROUND

[0005] In addressing climate change there is an increasing demand for rechargeable batteries, e.g., to enable electrification of transportation and to supplement renewable energy. Currently, lithium-ion batteries are becoming increasingly popular. They represent a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging.

[0006] As the demand for rechargeable batteries increases, increased focus is being placed on production speed. To achieve an effective production of rechargeable batteries, the design of the batteries as well as their manufacturing process can be optimized.

[0007] Gas release occurs during the formation process in battery production. Degassing is typically performed in a chamber, where the formation gas is prevented from venting as it is typically poisonous.

[0008] The chemical identity and quantity of these gases is directly related to the electrochemical reactions occurring between the electrodes and electrolyte components. Measurements of these gases would enable us to judge the quality of the formation and provide insights into the formation process. US2023178816A1 proposes a method for extraction of battery cell formation gas from a degas station. However, this method is complicated and requires space for routing the gas.

[0009] SUMMARY

[0010] The present disclosure aims at providing a technology that enables inline gas analysis measurements in a formation process for secondary cells. This is achieved by the proposed method and arrangement. According to a first aspect the disclosure relates to an arrangement for inline gas analysis measurements in a formation process for secondary cells. The arrangement comprises a gas analysis container, a plug extraction mechanism, and a gas analyser. The gas analysis container comprising a sample inlet designed to form fluid tight connection to an opening of a cell to be tested, and an outlet. The plug extraction mechanism is designed to pull a plug arranged to seal the opening, while the opening is connected to the sample inlet of the gas analysis container, whereby formation gas residing inside the gas analysis container is exhausted through the opening and flows into the gas analysis container. The gas analyser is arranged to be connected to the outlet of the gas analysis container, whereby gas spectra of the formation gas in the analysis container can be analysed. With the proposed method gas spectra can be measured using spectroscopy to achieve very high spectra resolution and analysis speed. This provides very detailed chemical information and fast analysis throughput times. The measurements can be used to judge quality of the formation and to provide insights for use in the formation process.

[0011] In some embodiments, the gas analysis container comprises a gas inlet arranged to receive carrier gas and / or purge gas. The gas let into the gas inlet can be used to carry gas exhausted from the secondary cell to the gas analyser. The gas can also be used to remove undesirable substances, contaminants, or gases from the gas analysis container.

[0012] In some embodiments, the sample inlet comprises a sealing device, such as a gasket, arranged to form the fluid tight seal. Thereby, not gas is let out from the gas analysis container.

[0013] In some embodiments, the opening comprises a tube arranged to connect the gas analysis container and the gas analyser. Thereby, the gas analyser does not need to be arranged right next to the gas analysis container. A tube typically also facilitates connection.

[0014] In some embodiments, the plug extraction mechanism is arranged to pull a plug to degas secondary cells in a formation process. Hence, the arrangement can be integrated with a mechanism already present in production. In some embodiments, the gas analyser comprises vibrational spectroscopy. Vibrational spectroscopy is a powerful technique for analysing gases.

[0015] In some embodiments, the arrangement comprises a vacuum system arranged to create a vacuum in the gas analysis container in-between samplings of cells. Thereby, gas can be extracted from the secondary cell more efficiently.

[0016] In some embodiments, the plug extraction mechanism is arranged to pull the plug to degas secondary cells in a formation process. Hence, the technique may be retrofitted onto existing solutions.

[0017] According to a second aspect the disclosure relates to a method for inline gas analysis measurements in a formation process for secondary cells. The method comprises forming fluid tight connection between a sample inlet of a gas analysis container and an opening of a cell to be tested. The method further comprises pulling a plug arranged in the opening, while the opening is connected to the sample inlet of the gas analysis container, whereby gas residing inside the gas analysis container is exhausted through the opening and flows into the gas analysis container and performing, using a gas analyser, spectral analysis on gas residing inside the gas analysis container. The method is associated with the same effects as the arrangement according to the first aspect.

[0018] In some embodiments, the method comprises inserting carrier gas and / or purge gas into the gas analysis container.

[0019] In some embodiments, the method comprises controlling a formation and aging process based on the spectral analysis.

[0020] In some embodiments, the pulling comprises pulling the plug to degas the secondary cell in a formation process.

[0021] In some embodiments, the performing comprises vibrational spectroscopy.

[0022] According to a third aspect the disclosure relates to formation system comprising the arrangement for inline gas analysis measurements according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The embodiments disclosed herein are illustrated by way of example, and by not by way of limitation, in the figures of the accompanying drawings. Like reference numerals refer to corresponding parts throughout the drawings, in which:

[0024] Figs. 1a-d illustrates pulling a plug to release gas from a secondary cell.

[0025] Fig. 2a illustrates an arrangement for inline gas analysis measurements in a formation process for secondary cells.

[0026] Fig. 2b illustrates a gas analysis container in further detail.

[0027] Fig. 3 illustrates a method for inline gas analysis measurements in a formation process for secondary cells.

[0028] DETAILED DESCRIPTION

[0029] The proposed technique is based on the idea of integrating an arrangement for in-line gas analysis where the dummy pin is pulled after formation. The gas to be analysed is carried to a high-path length gas analysis cell. Gas spectra are measured by vibrational spectroscopy with a dual frequency comb heterodyne approach to achieve very high spectra resolution and analysis speed. This provides very detailed chemical information and fast analysis throughput times.

[0030] Embodiments of the present disclosure will now be described more fully hereinafter, with reference to Figs 1 to 3. The same reference numbers are used throughout the figures. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those persons skilled in the art.

[0031] Fig. 1a illustrates a plug extraction mechanism 21 designed to pull a plug 11 (such as a pin) to release gas from a secondary cell 1 , hereafter simply cell 1. In some embodiments, the plug extraction mechanism 21 is arranged to pull a plug 11 to degas secondary cells in a formation process. In the illustrated example, the extraction mechanism 21 comprises automated gripper designed to pull a plug. The plug extraction mechanism 21 involves several mechanical components that work together to grasp and extract the plug 11 from an opening, such that gas can flow out from the secondary cell 1. In alternative embodiments, the extraction mechanism 21 may be implemented using other tools such as vacuum suction tools, magnetic tools, rotational tools, straps, pullers etc. The implementation of the extraction mechanism 21 typically depend on the type of plug and the type of secondary cell 1 .

[0032] The gripper typically consists of fingers 21a, or jaws, that open and close to grip the plug securely. Fig. 1b illustrates a cross section of the gripper seen from below in Fig. 1a. These fingers 21a can be made from materials like metal or durable plastic and are often equipped with rubber or soft coatings to improve grip and prevent slippage. For example, a surface with teeth-like or modified roughness can be used to improve the gripping. Fig. 1c illustrates how the fingers 21a are closing around the pin, such that the plug 1 is fixated in the gripper. Fig. 1d illustrates how the gripper thereafter moves upwards, whereby the plug 11 is pulled and gas is extracted from the opening 12 of a cell 1.

[0033] The plug extraction mechanism 21 uses actuators 21c to create the necessary motion to open and close the gripper's fingers. Pneumatic actuators, hydraulic actuators, or electric motors could be employed to power the gripping mechanism. To ensure proper gripping and pulling, sensors might be integrated. These sensors can detect the presence of the plug, measure the force applied during extraction, or ascertain if the gripper has successfully held the plug securely.

[0034] The plug extraction mechanism 21 also comprises a controller 21 b for managing the force applied to grip the plug and the motion used to extract it. These controls can be programmed within the automated system to regulate the speed, force, and sequence of movements necessary for plug extraction. The plug extraction mechanism 21 may also include positioning and guidance components, such as cameras, laser sensors, or proximity sensors, to locate the plug accurately before initiating the extraction process. These systems help ensure precise placement and extraction of the plug. Fig. 2a illustrates an arrangement 2 for inline gas analysis measurements in a formation process for secondary cells 1. The arrangement 2 comprises the plug extraction mechanism 21 (Fig. 1), a gas analysis container 22, and a gas analyser 27.

[0035] The gas analysis container 22, also known as a gas cell, is an enclosed (air-tight) chamber or container specifically designed for the analysis of gases using various spectroscopic techniques such as infrared (IR) spectroscopy or Raman spectroscopy. This cell allows for the controlled interaction of the gas sample with electromagnetic radiation, enabling the measurement and analysis of the sample's spectral characteristics. Fig. 2b illustrates a gas analysis container in further detail. The gas analysis container 22 comprises a sample inlet 23 designed to form fluid tight connection to an opening 12 of a cell 1 to be tested, and an outlet 26. Fig. 2b illustrates a gas analysis container in further detail.

[0036] The sample inlet 23 and the outlet 26 may be sealed to avoid leakage of sample gas, i.e., gas exhausted from the secondary cell 1. In other words, in some embodiments, the sample inlet 23 and / or the outlet 26 comprises a sealing device 24, such as a gasket, arranged to form the fluid tight seal. In some embodiments, the outlet 26 comprises a tube arranged to connect the gas analysis container 22 and the gas analyser 27. Hence, the tube can be used to convey the gas sample from the gas analysis container 22 to the gas analyser 27.

[0037] The arrangement 2 is designed to automatically capture a sample of gas residing in the secondary cell 1 in the gas analysis container 22. This is done by connecting the sample inlet 23 of the gas analysis container 22 before pulling the plug. The plug extraction mechanism 21 is designed to pull a plug 11 arranged to seal the opening 12, as illustrated in Fig. 1. More specifically, the plug extraction mechanism 21 is configured to pull the plug while the opening 12 is (fluidly) connected to the sample inlet 23 of the gas analysis container 22. Connected wherein means fluidly connected, such that gas can flow between the units, such as from the opening 12 to the inlet 23. Thereby, due to overpressure inside the secondary cell 1 , formation gas residing inside the gas analysis container 22 is exhausted through the opening and flows into the gas analysis container 22. Stated differently, gas exhausted from the secondary cell forms a sample in the gas analysis container 22. For example, carrier gas such as dry nitrogen, argon that does not affect an infrared light of the laser, can be used to push the sample gas from the sample inlet 23 to the outlet 26. In other words, a carrier gas may be used to carry the sample gas received via the sample inlet 23. Hence, in the illustrated embodiment a gas inlet 25 of the gas analysis container 22 is arranged to receive carrier gas. Thereby, the carrier gas is let into the gas analysis container 22. The gas inlet 25 can also be used to purge the gas analysis container 22 in-between samplings. In other words a purge gas can be used to remove undesirable substances, contaminants, or gases from the gas analysis container. The gas inlet is typically equipped with a valve such that flow through the gas inlet 24 can be controlled.

[0038] The gas analyser 27 is arranged to be connected to the outlet 26 of the gas analysis container 22, whereby gas spectra of the formation gas in the analysis container 22 can be analysed. To connect the gas analyser 27 to the gas analysis container 22 (i.e. the sample cell), various types of tubing, connectors, or specific fittings are used. The tubing transports the gas from the sample cell to the gas analyser 27 for analysis. It is typically essential to have a secure and airtight connection between the gas analyser 27 and the sample cell to prevent leaks and ensure accurate analysis. This might involve gaskets, seals, or other mechanisms for a tight fit between the two components. Some systems incorporate valves or control mechanisms to regulate the flow of gas into the gas analyser 27. These valves control the timing and volume of the gas sample being delivered for analysis.

[0039] The gas analyser 27 may for example measure the spectra using vibrational spectroscopy with a dual frequency comb heterodyne approach to achieve very high spectra resolution and analysis speed. Vibrational spectroscopy is an analytical technique used to study molecular structures by observing how molecules interact with electromagnetic radiation. It provides information about the vibrational motion of atoms within a molecule, specifically how the bonds between atoms stretch, bend, or vibrate.

[0040] In some embodiments the arrangement 2 comprises a vacuum system 28 arranged to create a vacuum. For example, the vacuum system 28 may be used to create a vacuum in the gas analysis container 22 before pulling the plug. Thereby, gas from the secondary cell 1 can be drawn into the gas analysis container 22 for analysis, even if there is no overpressure. The vacuum system 28 may also be used to reduce the background interference of other gases, allowing for more accurate measurement of the gas of the secondary cell 1 . This is especially important in applications where trace amounts of specific gases need to be detected. The vacuum system can also be used for purification to remove impurities or unwanted gases from a sample.

[0041] Fig. 3 is a flow chart of the proposed method for inline gas analysis measurements in a formation process for secondary cells. The method is for example performed by the arrangement 2 (Fig. 2). The method may be controlled by a computer program comprising instructions which, when the program is executed by a computer, cause the arrangement 2 to carry out the method. The method may be performed during production of secondary cells, such as during formation of the secondary cells 1 .

[0042] The method is for example performed during a degassing step of a formation process. Degassing involves the removal of gases, primarily oxygen and moisture, from the electrolyte and other components of the secondary cell during the manufacturing process. Hence, the method comprises extracting a sample of the gas exhausted in the degassing step in a formation process. To do that a tight seal is formed around the opening where gas is exhausted. The seal may be obtained by a gasket or similar. In other words, the method comprises forming S1 fluid tight connection between a sample inlet 23 of a gas analysis container 22 and an opening 12 of a cell 1 to be tested.

[0043] Before the plug is pulled the gas analysis container 22 may be purged. In some embodiments, the method comprises inserting S2 purge gas into the gas analysis container 22. This is done by opening a valve of the gas inlet 24 to let in the purge gas. In some embodiments a vacuum is created in the gas analysis container 22 before pulling the plug.

[0044] The plug is then pulled such that gas from the secondary cell is exhausted into the gas analysis container 22. In other words, the method comprises pulling S3 a plug 11 arranged in the opening 12, while the opening 12 is connected to the sample inlet 23 of the gas analysis container 22, whereby gas residing inside the gas analysis container 22 is exhausted through the opening and flows into the gas analysis container 22. The gas exhausted is caused by overpressure inside the secondary cell 1 . A sample of the gas exhausted from the secondary cell is now present in the gas analysis container 22.

[0045] Carrier gas may be used to carry the sample. Hence, in some embodiments, the method comprises inserting S2 carrier gas into the gas analysis container 22. This is done by opening a valve of the gas inlet 24 to let in the carrier gas.

[0046] The gas sample can now be analysed using suitable methods. In other words, the method comprises performing S4, using a gas analyser 27, spectral analysis on gas residing inside the gas analysis container 21 .

[0047] Information revealed from the gas analysis can be used to control the manufacturing process. For example, quality can be analysed, and poor cells can be scrapped before aging. The information can also be used to perform quality control of preceding production steps. It may also be possible to adapt the formation process based on the information. In some embodiments, the method comprises controlling S5 a formation and aging process based on the spectral analysis

[0048] The proposed technique has been described with reference to lithium-ion cells, but it should be appreciated that method for other types of cells including cells made from solid state materials, such as graphene. Such cells are expected to be more commonly used in the future.

[0049] The terminology used in the description of the embodiments as illustrated in the accompanying drawings is not intended to be limiting of the described method, control arrangement or computer program. Various changes, substitutions and / or alterations may be made, without departing from disclosure embodiments as defined by the appended claims.

[0050] The term “or” as used herein, is to be interpreted as a mathematical OR, i.e., as an inclusive disjunction; not as a mathematical exclusive OR (XOR), unless expressly stated otherwise. In addition, the singular forms "a", "an" and "the" are to be interpreted as “at least one”, thus also possibly comprising a plurality of entities of the same kind, unless expressly stated otherwise. It will be further understood that the terms "includes", "comprises", "including" and / or "comprising", specifies the presence of stated features, actions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, components, and / or groups thereof. A single unit such as e.g. a processor may fulfil the functions of several items recited in the claims.

Claims

CLAIMS1. An arrangement (2) for inline gas analysis measurements in a formation process for secondary cells (1), the arrangement (2) comprising:- a gas analysis container (22) comprising a sample inlet (23) designed to form fluid tight connection to an opening (12) of a cell (1) to be tested, and an outlet (26),- a plug extraction mechanism (21) designed to pull a plug (11) arranged to seal the opening (12), while the opening (12) is connected to the sample inlet (23) of the gas analysis container (22), whereby formation gas residing inside the cell (1) is exhausted through the opening and flows into the gas analysis container (22) and- a gas analyser (27) arranged to be connected to the outlet (26) of the gas analysis container (22), whereby gas spectra of the formation gas in the analysis container (22) can be analysed.

2. The arrangement (2) according to claim 1 , wherein the gas analysis container (22) comprises a gas inlet (25) arranged to receive carrier gas and / or purge gas.

3. The arrangement (2) according to claim 1 or 2, wherein the sample inlet comprises a sealing device (24), such as a gasket, arranged to form the fluid tight seal.

4. The arrangement (2) according to any one of the preceding claims, wherein the outlet (26) comprises a tube arranged to connect the gas analysis container (22) and the gas analyser (27).

5. The arrangement (2) according to any one of the preceding claims, wherein the plug extraction mechanism (21) is arranged to pull a plug (11) to degas secondary cells in a formation process.

6. The arrangement (2) according to any one of the preceding claims, wherein the gas analyser comprises vibrational spectroscopy.

7. The arrangement (2) according to any one of the preceding claims, comprising a vacuum system arranged to create a vacuum in the gas analysis container (22) inbetween samplings of cells.

8. The arrangement (2) according to any one of the preceding claims, wherein the plug extraction mechanism (21) is arranged to pull the plug (11) to degas secondary cells in a formation process.

9. A formation system comprising the arrangement according to any one of claims 1 to 7.

10. A method for inline gas analysis measurements in a formation process for secondary cells (1), the arrangement (2) comprising:- forming (S1 ) fluid tight connection between a sample inlet (23) of a gas analysis container (22) and an opening (12) of a secondary cell (1 ) to be tested,- pulling (S3) a plug (11) arranged in the opening (12), while the opening (12) is connected to the sample inlet (23) of the gas analysis container (22), whereby gas residing inside cell (1) is exhausted through the opening and flows into the gas analysis container (22) and- performing (S4), using a gas analyser (27), spectral analysis on gas residing inside the gas analysis container (22).

11. The method according to claim 10, purging carrier gas and / or purge gas into the gas analysis container (22).

12. The method according to any one of claims claim 10 or 11 , wherein the pulling comprises pulling the plug (11 ) to degas the secondary cell in a formation process.

13. The method according to any one of claims claim 10 to 12, wherein the performing (S4) comprises vibrational spectroscopy.

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