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EP-4164049-B1 - ENERGY STORAGE ELEMENT AND METHOD OF MANUFACTURING SAME

EP4164049B1EP 4164049 B1EP4164049 B1EP 4164049B1EP-4164049-B1

Inventors

  • ELMER, MARTIN
  • Soldner, Andreas
  • STERN, RAINER

Dates

Publication Date
20260506
Application Date
20211006

Claims (12)

  1. Energy storage element (100) with the features a. It comprises a cathode (101) and an anode (102) which are parts of an assembly (109) in which they are present, separated by a separator or solid electrolyte layer (110), in the sequence cathode (101) / separator or solid electrolyte layer (110) / anode (102), b. the cathode (101) comprises a cathode current collector (101a) and a positive electrode material (117), c. the cathode current collector (101a) has • a main region (101b) loaded on both sides with a layer of the positive electrode material (117), and • a free edge strip (101c) which extends along an edge of the cathode current collector (101a) and which is not loaded with the positive electrode material (117), d. the anode (102) comprises an anode current collector (102a) and a negative electrode material (118), e. the anode current collector (102a) has • a main region (101b) loaded on both sides with a layer of the negative electrode material (118), and • a free edge strip (102c) which extends along an edge of the anode current collector (102a) and which is not loaded with the negative electrode material (118), f. the cathode (101) and the anode (102) are formed and/or arranged within the electrode-separator assembly (109) relative to one another in such a way that the free edge strip (101c) of the cathode current collector (101a) protrudes from one side (109a) of the assembly (109) and the free edge strip (102c) of the anode current collector (102a) protrudes from another side (109b) of the assembly (109), and g. the energy storage element comprises a first contact sheet metal member (119) which is in direct contact with one of the free edge strips (101c, 102c), and a second contact sheet metal member (120) which is in direct contact with the other of the free edge strips (101c, 102c), and wherein h. at least one of the edge strips (101c, 102c) being in direct contact with one of the contact sheet metal members (119, 120) has, as a result of a folding and/or a rolling-up process and of a calendering process, a thickness which corresponds to the thickness of the associated cathode (101) or anode (102) in the adjacent main region (101b, 102b) coated on both sides with electrode material (117, 118).
  2. Energy storage element according to claim 1 with the following additional features: a. The electrodes (101, 102) and the current collectors (101a, 102a) as well as the layers of electrode materials (117, 118) are ribbon-shaped, b. It comprises at least one ribbon-shaped separator (110, 111) or at least one ribbon-shaped solid electrolyte layer (110), c. the assembly (109) is in the form of a cylindrical winding in which the electrodes (101, 102) and the at least one separator (110, 111) are spirally wound around a winding axis, wherein the assembly (109) comprises a first and a second terminal end face (109a, 109b) and a winding shell, and the free edge strip (101c) of the cathode current collector (101a) protrudes from the first end face (109a) and the free edge strip (102c) of the anode current collector (102a) protrudes from the second end face (109b), d. It comprises a cylindrical housing, in particular a cylindrical metal housing, comprising a circumferential housing shell and, at the end faces, a circular bottom and a lid, and e. In the housing, the assembly (109) in the form of a winding is axially aligned so that the winding shell abuts the inside of the circumferential housing shell.
  3. Energy storage element according to claim 2 with at least one of the following additional features: a. The ribbon-shaped positive electrode (101) and thus also the free edge strip (101c) of the cathode current collector (101a) protruding from the first end face (109a) comprises a radial sequence of adjacent turns (160-174) in the winding. b. Each of the turns comprises a section of the edge strip (101c) thickened as a result of the folding and/or the winding process. c. In adjacent turns, the sections of the thickened edge strip (101c) are in direct contact with each other. d. The free edge strip (101c) of the cathode current collector (101a) forms a continuous metal layer in the direction perpendicular to the first end face (109a), which covers at least 80% of the end face (109a).
  4. Energy storage element according to claim 2 or according to claim 3 with at least one of the following additional features: a. The ribbon-shaped negative electrode (102) and thus also the free edge strip (102c) of the anode current collector (102) protruding from the second end face (109b) comprises a radial sequence of adjacent turns (141-156) in the winding. b. Each of the turns comprises a section of the edge strip (102c) thickened as a result of the folding and/or the winding process. c. In adjacent turns, the sections of the thickened edge strip (102c) are in direct contact with each other. d. The free edge strip (102c) of the anode current collector (102a) forms a continuous metal layer in the direction perpendicular to the second end face (109b), which covers at least 80 % of the end face (109b).
  5. Energy storage element according to claim 1 with the following additional features: a. The assembly (109) is in the form of a prismatic stack in which the cathode (101) and the anode (102) are stacked together with further cathodes (103, 105, 107) and anodes (104, 106, 108). b. The electrodes (101, 102, 103, 104, 105, 106, 107 and 108) and the current collectors (101a, 102a, 103a, 104a, 105a, 106a, 107a and 108a) as well as the layers of the electrode materials are polygonal, in particular rectangular. c. It comprises at least one ribbon-shaped or polygonal, in particular rectangular, separator (110, 111, 112, 113, 114, 115, 116) or at least one ribbon-shaped or polygonal, in particular rectangular, solid electrolyte, d. The stack is enclosed in a prismatic housing (125).
  6. Energy storage element according to claim 5 with at least one of the following additional features: a. Each of the cathodes (101, 103, 105, 107) of the stack is characterized by the edge strip (101c, 103c, 105c, 107c) thickened as a result of the folding and/or rolling process. b. Each of the anodes (102, 104, 106, 108) of the stack is characterized by the edge strip (102c, 104c, 106c, 108c) thickened as a result of the folding and/or rolling process. c. The free edge strips (101c, 103c, 105c, 107c) of the cathode current collectors of the cathodes of the stack protrude from one side of the stack and are in direct contact with the first contact sheet metal member (119). d. The free edge strips (102c, 104c, 106c, 108c) of the anode current collectors of the anodes of the stack protrude from another side of the stack and are in direct contact with the second contact sheet metal member (120).
  7. Energy storage element according to claim 5 or according to claim 6 with at least one of the following additional features: a. The free edge strips (101c, 103c, 105c, 107c) of the cathode current collectors are arranged parallel to each other. b. Of the free edge strips (101c, 103c, 105c, 107c) of the cathode current collectors, adjacent edge strips are in direct contact with each other. c. The free edge strips (101c, 103c, 105c, 107c) of the cathode current collectors form a continuous metal layer in the direction perpendicular to the side of the stack from which they protrude, which completely covers at least 80 % of the side.
  8. Energy storage element according to any one of claims 5 to 7, having at least one of the following additional features: a. The free edge strips (102c, 104c, 106c, 108c) of the anode current collectors are arranged parallel to each other. b. Of the free edge strips (102c, 104c, 106c, 108c) of the anode current collectors, adjacent edge strips are in direct contact with each other. c. The free edge strips (102c, 104c, 106c, 108c) of the anode current collectors form a continuous metal layer in the direction perpendicular to the side of the stack from which they protrude, which completely covers at least 80% of the side.
  9. Energy storage element according to claim 1 with the following additional features: a. The first contact sheet metal member (119) is connected to the free edge strip (101c) of the cathode current collector (101a) by welding and/or the second contact sheet metal member (120) is connected to the free edge strip (102c) of the anode current collector (102a) by welding. b. The first contact sheet metal member (119) is mechanically connected to the free edge strip (101c) of the cathode current collector (101a) and/or the second contact sheet metal member (120) is mechanically connected to the free edge strip (102c) of the anode current collector.
  10. Method of manufacturing an energy storage element (100) with the features a. It comprises a cathode (101) and an anode (102) which are parts of an assembly (109) in which they are present, separated by a separator or solid electrolyte layer (110), in the sequence cathode (101) / separator or solid electrolyte layer (110) / anode (102), b. the cathode (101) comprises a cathode current collector (101a) and a positive electrode material (117), c. the cathode current collector (101a) has • a main region (101b) loaded on both sides with a layer of the positive electrode material (117), and • a free edge strip (101c) which extends along an edge of the cathode current collector (101a) and which is not loaded with the positive electrode material (117), d. the anode (102) comprises an anode current collector (102a) and a negative electrode material (118), e. the anode current collector (102a) has • a main region (102b) loaded on both sides with a layer of the negative electrode material (118), and • a free edge strip (102c) which extends along an edge of the anode current collector (102a) and which is not loaded with the negative electrode material (118), f. the cathode (101) and the anode (102) are formed and/or arranged within the electrode-separator assembly (109) relative to one another in such a way that the free edge strip (101c) of the cathode current collector (101a) protrudes from one side (109a) of the assembly (109) and the free edge strip (102c) of the anode current collector (102a) protrudes from another side (109b) of the assembly (109), and g. the energy storage element comprises a first contact sheet metal member (119) which is in direct contact with one of the free edge strips (101c, 102c), and a second contact sheet metal member (120) which is in direct contact with the other of the free edge strips (101c, 102c), wherein the method comprises the following step: h. Before the assembly (109) is formed, at least one edge strip (101c, 102c) is subjected to a folding and/or rolling process and to a calendering process, as a result of which it has a thickness which corresponds to the thickness of the associated cathode (101) or anode (102) in the adjacent main region (101b, 102b) coated on both sides with electrode material (117, 118).
  11. The method according to claim 10, comprising the following sequence of steps: a. The current collectors (101a, 102a) coated on both sides with the electrode material are provided. b. At least one of the edge strips (101c, 102c) is subjected to the folding and/or rolling-up process, obtaining at least one folded and/or rolled-up edge strip. c. the current collectors (101a, 102a) coated on both sides with the electrode material, including the at least one folded and/or rolled-up edge strip, are subjected to the calendering process.
  12. A method according to claim 10 or according to claim 11 comprising at least one of the following additional features: a. The folding process comprises multiple folding. b. The folding process results in a multilayer edge strip. c. The folding process is preceded by a targeted structural weakening of the edge strip.

Description

Die Erfindung betrifft ein Energiespeicherelement, das sich zur Bereitstellung sehr hoher Ströme eignet, sowie ein Verfahren zur Herstellung eines solchen Energiespeicherelements. ANWENDUNGSGEBIET UND STAND DER TECHNIK Elektrochemische Energiespeicherelemente sind dazu in der Lage, gespeicherte chemische Energie durch eine Redoxreaktion in elektrische Energie umzuwandeln. Die einfachste Form eines elektrochemischen Energiespeicherelements ist die elektrochemische Zelle. Sie umfasst eine positive und eine negative Elektrode, die von einem Separator voneinander getrennt sind. Bei einer Entladung werden an der negativen Elektrode durch einen Oxidationsprozess Elektronen freigesetzt. Hieraus resultiert ein Elektronenstrom, der von einem externen elektrischen Verbraucher abgegriffen werden kann, für den die elektrochemische Zelle als Energielieferant dient. Zugleich kommt es zu einem der Elektrodenreaktion entsprechenden Ionenstrom innerhalb der Zelle. Dieser Ionenstrom durchquert den Separator und wird durch einen ionenleitenden Elektrolyten ermöglicht. Wenn die Entladung reversibel ist, also die Möglichkeit besteht, die bei der Entladung erfolgte Umwandlung von chemischer Energie in elektrische Energie wieder umzukehren und die Zelle wieder zu laden, spricht man von einer sekundären Zelle. Die bei sekundären Zellen allgemein übliche Bezeichnung der negativen Elektrode als Anode und die Bezeichnung der positiven Elektrode als Kathode bezieht sich auf die Entladefunktion der elektrochemischen Zelle. Für viele Anwendungen werden als Energiespeicherelemente heute sekundäre Lithium-Ionen-Zellen eingesetzt, da diese hohe Ströme bereitstellen können und sich durch eine vergleichsweise hohe Energiedichte auszeichnen. Sie basieren auf dem Einsatz von Lithium, welches in Form von Ionen zwischen den Elektroden der Zelle hin und her wandern kann. Die negative Elektrode und die positive Elektrode einer Lithium-Ionen-Zelle werden in der Regel von sogenannten Kompositelektroden gebildet, die neben elektrochemisch aktiven Komponenten auch elektrochemisch inaktive Komponenten umfassen. Als elektrochemisch aktive Komponenten (Aktivmaterialien) für sekundäre Lithium-Ionen-Zellen kommen prinzipiell sämtliche Materialien in Frage, die Lithium-Ionen aufnehmen und wieder abgeben können. Für die negative Elektrode werden hierfür beispielsweise Partikel auf Kohlenstoffbasis, wie beispielsweise graphitischer Kohlenstoff, eingesetzt. Als Aktivmaterialien für die positive Elektrode können beispielsweise Lithiumcobaltoxid (LiCoO2), Lithiummanganoxid (LiMn2O4), Lithiumeisenphosphat (LiFePO4) oder Derivate hiervon eingesetzt werden. Die elektrochemisch aktiven Materialien sind in der Regel in Partikelform in den Elektroden enthalten. Als elektrochemisch inaktive Komponenten umfassen die Kompositelektroden im Allgemeinen einen flächigen und/oder bandförmigen Stromkollektor, beispielsweise eine metallische Folie, der als Träger für das jeweilige Aktivmaterial dient. Der Stromkollektor für die negative Elektrode (Anodenstromkollektor) kann beispielsweise aus Kupfer oder Nickel und der Stromkollektor für die positive Elektrode (Kathodenstromkollektor) beispielsweise aus Aluminium gebildet sein. Weiterhin können die Elektroden als elektrochemisch inaktive Komponenten einen Elektrodenbinder (z. B. Polyvinylidenfluorid (PVDF) oder ein anderes Polymer, beispielsweise Carboxymethylzellulose), leitfähigkeitsverbessernde Additive und andere Zusätze umfassen. Der Elektrodenbinder gewährleistet die mechanische Stabilität der Elektroden und häufig auch die Haftung des Aktivmaterials auf den Stromkollektoren. Als Elektrolyten umfassen Lithium-Ionen-Zellen in der Regel Lösungen von Lithiumsalzen wie Lithiumhexafluorophosphat (LiPF6) in organischen Lösungsmitteln (z. B. Ether und Ester der Kohlensäure). Die Kompositelektroden werden bei der Herstellung einer Lithium-Ionen-Zelle mit einem oder mehreren Separatoren zu einem Verbundkörper kombiniert. Hierbei werden die Elektroden und Separatoren meist unter Druck, gegebenenfalls auch durch Lamination oder durch Verklebung, miteinander verbunden. Die grundsätzliche Funktionsfähigkeit der Zelle kann dann durch Tränkung des Verbunds mit dem Elektrolyten hergestellt werden. In vielen Ausführungsformen wird der Verbundkörper in Form eines Wickels gebildet oder zu einem Wickel verarbeitet. Alternativ kann es sich bei dem Verbundkörper auch um einen Stapel aus Elektroden handeln. Für Anwendungen im Automobilbereich, für E-Bikes oder auch für andere Anwendungen mit hohem Energiebedarf wie z.B. in Werkzeugen werden Lithium-Ionen-Zellen mit möglichst hoher Energiedichte benötigt, die gleichzeitig in der Lage sind, mit hohen Strömen beim Laden und Entladen belastet zu werden. In der WO 2017/215900 A1 sind zylindrische Rundzellen beschrieben, bei denen ein Verbundkörper aus bandförmigen Elektroden gebildet ist und in Form eines Wickels vorliegt. Die Elektroden weisen jeweils mit Elektrodenmaterial beladene Stromkollektore