Patent Application
20250121474
The present invention relates to a method for producing an electrode for an electrical energy storage cell, an electrode, and an energy storage cell.
In electrical energy storage cells, such as lithium-ion cells, liquid electrolytes are used to ensure the ion transport between the battery electrodes. The electrolyte distribution significantly influences the ionic conductivity and the discharge capacity of the cell and is thus a decisive factor for the performance and quality of the cell. For this reason, complete and uniform permeation of the pore volume of the coating of the electrode with electrolyte is desired. For this purpose, the cells have to be stored for a long time after the electrolyte filling in order to enable the distribution of the electrolyte, driven by capillary forces, within the electrode structure. To increase the volumetric energy density as much as possible and improve the contacting of the particles within the coating of the electrode, the electrodes, thus the current collector foils coated with coating material, are calendered. The coating surface is compacted and cavities within the coating are reduced in size in this case. In addition to the above-mentioned positive effects which accompany the calendering, however, this process also has the result that the soaking of the electrolyte into the electrode coating is obstructed. The electrolyte filling accordingly takes longer, which slows the production process and makes it more costly.
It is therefore an object of the present invention to provide a method for producing an electrode, an electrode, and an energy storage cell, which eliminate the above-mentioned disadvantages, wherein in particular an electrode is provided which meets the highest performance requirements with low production costs at the same time.
This object is achieved by a method, by an electrode, and by an energy storage cell, in accordance with the independent claims. Further advantages and features result from the dependent claims and the description and the appended figures.
According to the invention, a method for producing an electrode for an electrical energy storage cell comprises the following steps:
The carrier material is typically a, preferably metallic, carrier foil, also called a collector foil. Copper is typically used as the material for the carrier material or the carrier foil of the anode, and an aluminum foil is typically used for the carrier material or the carrier foil of the cathode. Typical foil thicknesses vary depending on the cell design between 4 μm and 25 μm. The carrier materials/carrier foils are preferably coated over a width of up to 900 mm in a roll-to-roll process. The coating can take place on one or both sides, sequentially or simultaneously. The coating can advantageously be activated or roughened via the blasting. For example, a porosity of the coating is expediently changed or adjusted, expediently in particular increased, at least close to the surface, by means of blasting.
Blasting technology is a subfield of surface technology in which blasting agents are guided at high speed onto a workpiece. Compressed air, compressed liquids, electrostatic or electromagnetic fields, and impellers are available as energy carriers. The blasting result is substantially dependent on the type of the selected blasting agent, in addition to the method control itself. Depending on the type of the method control and the blasting agents used, greatly varying technical effects can be achieved. In the present case, blasting is preferably used to activate the coating, in particular to roughen it and/or to create pores. Further possible effects which can be subsumed under the expression “activating” are in addition: solidifying, roughening, structuring, or causing abrasive effects in general.
According to one preferred embodiment, compressed air blasting is used in the present case. A preferably solid blasting agent is used in this case, which is accelerated by compressed air as it flows through a nozzle. Due to the impact of the blasting agents on the surface of a workpiece to be processed, in the present case the coating, this can be removed, solidified, and/or formed or structured, wherein the above-mentioned list is not to be understood as exhaustive.
According to one particularly preferred embodiment, the method comprises the following step:
CO2 snow blasting is a preferred compressed air method since the abrasive effect is very minor and is thus optimally suitable for the above-mentioned purpose. Moreover, no residues are retained, which would possibly influence the chemistry of the coating. Carbon dioxide is used as the blasting agent in CO2 snow blasting.
A two-material ring nozzle is preferably used in the present case, since this method variant is less abrasive. Alternatively, a blasting nozzle having an agglomeration chamber can also be used.
In the present case in CO2 snow blasting, CO2 snow particles are expediently accelerated with the aid of a compressed air jet onto the coating, where they have, inter alia, an abrasive effect. In this way, small channels and/or pores are created there, through which the electrolyte can penetrate and distribute itself. The permeation of the pore volume of the coating is accelerated and the service life of the cell after the electrolyte filling can be shortened. This results in a significant reduction of the production costs for energy storage cells or electrodes.
The method preferably comprises the following step:
During calendering, the coated carrier material is compacted by one or more rotating pairs of rollers. A defined linear pressure is generated in this case, via which the porosity of the coating is reduced and the contacting of the particles within the coating is improved. These two procedures can now advantageously be decoupled from one another by the subsequent blasting of the coating. In particular, for example, the porosity can be increased again via the blasting after the calendering.
According to one embodiment, the method comprises the following step:
The blasting is expediently integrated directly or immediately into the roll-to-roll process. The blasting expediently takes place directly after the calendering and is integrated into the roll-to-roll process. The device for blasting or the blasting device is expediently installed fixed in place for this purpose while the carrier material or the carrier foil is moved. This can take place continuously or intermittently in accordance with the blasting.
The device for blasting comprises, according to one embodiment, multiple nozzles which are installed, for example, in a row transverse to the web direction. The nozzles can be designed as fixed or movable, so that if needed a blasting angle relative to the coating surface can also advantageously be adjusted.
According to one embodiment, the method comprises the following step:
According to one embodiment, it can be advantageous not to blast the entire coating over the full surface. The regional or local blasting enables only local or regional activation or regional adjustment of the properties of the coating/electrode. Strips in which the porosity is increased can be created, for example, along a web direction of the electrode web.
According to one preferred embodiment, the blasting is guided so that the coating is uniformly blasted, the coating is thus activated as uniformly as possible in all areas.
According to one embodiment, the method comprises the following step:
In intermittent blasting, an area of the coating is blasted using, for example, only one, possibly also multiple blasting strikes. The intermittent blasting can be advantageous if the coating is only to be processed as close as possible to the surface.
Alternatively, continuous blasting takes place. The blasting device runs continuously in this case.
According to one embodiment, the method comprises the following steps:
The above-mentioned method chain can also include the method step of “slitting”, which is a severing process in which a broad electrode band (mother coil) is divided into multiple smaller electrode bands (daughter coil). In the present case, the blasting is expediently integrated into the roll-to-roll process, cf. the above-mentioned unrolling or rolling up. For this purpose, multiple means for blasting, in particular CO2 snow blasting nozzles, are expediently combined to form an array (cf. the above-mentioned row) and attached above the electrode web passing through underneath. Complete blasting over the entire coating width can thus be enabled.
The method expediently comprises the following step:
The compaction of the electrode surface or the coating by the calendering has the result in particular for cathodes that the soaking of the electrolyte into the coating is made more difficult. Accordingly, the electrode is preferably a cathode in the present case.
Furthermore, the invention is directed to an electrode, in particular a cathode, in particular produced according to the method according to the invention, wherein the porosity of the electrode coating is adjusted by means of blasting, in particular CO2 snow blasting. The advantages mentioned in conjunction with the method apply analogously and correspondingly to the electrode.
Furthermore, the invention is directed to an energy storage cell, comprising an electrode according to the invention. According to one preferred embodiment, the energy storage cell is an energy storage cell as is used in an energy storage device for partially or fully electrically operated motor vehicles. Energy storage cells of the type under discussion are energy storage cells which are filled with a liquid electrolyte.
Further advantages and features result from the following description of an embodiment of the method with reference to the appended figures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 125 494.9 | Oct 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/074555 | 9/5/2022 | WO |
