EP-4736249-A1 - BUSBAR-OVER-ELECTRODE INTERCONNECT SYSTEMS FOR SECONDARY BATTERIES AND METHODS OF ASSEMBLING THE SAME

EP4736249A1EP 4736249 A1EP4736249 A1EP 4736249A1EP-4736249-A1

Abstract

An electrode assembly includes unit cells stacked in a longitudinal direction, each unit cell including an electrode structure, a separator, and a counter-electrode structure. The electrode structure includes an electrode current collector and an electrode active material layer. The counter-electrode structure includes a counter-electrode current collector and a counter-electrode active material layer. An end portion of the counter-electrode current collector extends past the counter-electrode active material and the separator. The end portion of the counter-electrode current collector is bent to define a bent end portion of the respective counter-electrode current collector. The bent end portions of at least some of the counter-electrode current collectors overlap the bent end portion of an adjacent counter-electrode current collector. The electrode assembly also includes a counter-electrode busbar extending across and attached to the bent end portions such that the counter-electrode current collectors are electrically connected to and are disposed inboard of the counter-electrode busbar.

Inventors

NOELLE, Daniel J.
ARMSTRONG, MICHAEL J.
KOOL, Miles A.M.
BUSACCA, ROBERT S.
CARDOZO, Benjamin L.
RAMASUBRAMANIAN, MURALI

Assignees

Enovix Corporation

Dates

Publication Date: 20260506
Application Date: 20240612

Claims (10)

1. An electrode assembly for use with a secondary battery, the electrode assembly defining mutually perpendicular transverse, longitudinal, and vertical directions corresponding to an X axis, a Y axis, and a Z axis, respectively, of a three-dimensional Cartesian coordinate system, the electrode assembly comprising: a population of unit cells being stacked in the longitudinal direction, each member of the unit cell population including an electrode structure, a separator structure, and a counterelectrode structure, wherein: the electrode structure comprises an electrode current collector and an electrode active material layer, the electrode structure extending in the transverse direction; the counter-electrode structure comprises a counter-electrode current collector and a counter-electrode active material layer, the counter-electrode structure extending in the transverse direction, an end portion of the counter-electrode current collector extending past the counter-electrode active material and the separator structure in the transverse direction, and the end portion of the counter-electrode current collector being bent towards the longitudinal direction to define a bent end portion of the respective counter-electrode current collector; and the bent end portions of at least some of the counter-electrode current collectors overlap the bent end portion of an adjacent counter-electrode current collector in a Y-Z plane of the electrode assembly defined by the Y and Z axes; and a counter-electrode busbar being attached to the bent end portions of the counterelectrode current collectors such that the counter-electrode current collectors are electrically connected to the counter-electrode busbar, the counter-electrode busbar extending across the bent end portions in the Y-Z plane such that the bent end portions of the counter-electrode current collectors are disposed inboard of the counter-electrode busbar.
2. The electrode assembly as set forth in claim 1, wherein the electrode structures comprise negative electrode structures, and the counter-electrode structures comprise positive electrode structures.
3. The electrode assembly as set forth in claim 2, wherein the counter- el ectrode current collectors comprise a material selected from the group consisting of aluminum, nickel, cobalt, titanium, tungsten, iron, stainless steel, and alloys thereof.
4. The electrode assembly as set forth in claim 2, wherein the counter- el ectrode current collectors comprise aluminum.
5. The electrode assembly as set forth in claim 1, wherein the counter- el ectrode busbar is directly welded to the bent end portions of the counter-electrode current collectors.
6. The electrode assembly as set forth in claim 1, wherein the overlapping bent end portions of the counter-electrode current collectors are attached by at least one of welding, soldering, and gluing.
7. The electrode assembly as set forth in claim 1, wherein a cumulative thickness of the overlapping bent end portions of the counter-electrode current collectors, measured in the transverse direction, is at least two times greater than an individual thickness of the counter-electrode current collectors, measured in the longitudinal direction.
8. The electrode assembly as set forth in claim 7, wherein the cumulative thickness of the overlapping bent end portions of the counter-electrode current collectors is approximately four times greater than the individual thickness of the counter-electrode current collectors.
9. The electrode assembly as set forth in claim 1, wherein the end portion of the counter-electrode current collector comprises first and second tabs each extending past the counter-electrode active material and the separator structure in the transverse direction, the first and second tabs of each counter-electrode current collector being bent towards the longitudinal direction, the first and second tabs of at least some of the counter-electrode current collectors overlap the first and second tab, respectively, of an adjacent counterelectrode current collector in the Y-Z plane of the electrode assembly, the counter-electrode busbar being attached to and extending across the first tabs, the second tabs, or both the first and second tabs of the counter-electrode current collectors in the Y-Z plane of the electrode assembly such that the first tabs, the second tabs, or both the first and second tabs are disposed inboard of the counter-electrode busbar.
10. The electrode assembly as set forth in claim 9, wherein the counter- el ectrode busbar is attached to and extends across the first tabs and second tabs in the Y-Z plane of the electrode assembly such that the first and second tabs are disposed inboard of the second counter-electrode busbar.

Description

BUSBAR-OVER-ELECTRODE INTERCONNECT SYSTEMS FOR SECONDARY BATTERIES AND METHODS OF ASSEMBLING THE SAME FIELD [0001] The field of the disclosure relates generally to energy storage technology, such as battery technology. More specifically, the field of the disclosure relates to electrode assemblies that include busbar-over-electrode electrical interconnections, secondary batteries including such electrode assemblies, and methods of assembling such electrode assemblies. BACKGROUND [0002] Secondary batteries, such as lithium based secondary batteries, have become desirable energy sources due to their comparatively high energy density, power and shelf life. Examples of lithium secondary batteries include non-aqueous batteries such as lithium-ion and lithium-polymer batteries. Secondary batteries typically have two-dimensional laminar architectures, such as planar or spirally wound (i.e., jellyroll) laminate structures, where a surface area of each laminate is approximately equal to its geometric footprint (ignoring porosity and surface roughness). [0003] Three-dimensional secondary batteries may provide increased capacity and longevity compared to laminar secondary batteries. Three-dimensional battery architectures (e.g., interdigitated electrode arrays) have been proposed in the literature to provide higher electrode surface area, higher energy and power density, improved battery capacity, and improved active material utilization compared with two-dimensional architectures (e.g., flat and spiral laminates). For example, reference to Long et al., “Three-dimensional battery architectures,” Chemical Reviews, 2004, 104, 4463-4492, may help to illustrate the state of the art in proposed three-dimensional battery architectures, and is therefore incorporated by reference as non-essential subject matter herein. [0004] Known three-dimensional secondary batteries include electrode assemblies having a multitude of electrode and counter-electrode substructures in alternating stacked arrangement to build capacity of the secondary battery. The electrode and the counter-electrode substructures include electrochemically active material into which a carrier ion, such as lithium, inserts and extracts. As the battery is discharged, carrier ions are extracted from the electrode substructures and inserted into the counter-electrode substructures. As the battery is charged, the carrier ions are extracted from the counter-electrode substructures and inserted into the electrode substructures. The electrode and counter-electrode substructures are typically connected to respective electrode and counter-electrode terminals of the secondary battery via interconnection tabs disposed along one or more outer edges of the electrode assembly to facilitate charging and discharging the secondary battery. The interconnection tabs include electrode tabs connected to the electrode terminal and counter-electrode tabs connected to the counter-electrode terminal. The tabs may be connected to the respective terminals by electrode and counter-electrode busbars that are respectively attached to the electrode tabs and the counter-electrode tabs. [0005] The interconnection tabs may be formed as end portions of current collectors of the electrode and counter-electrode substructures that extend past the electrochemically active material along one or more edges of the electrode assembly. The current collectors and the tabs may be constructed of thin electrically conductive (e.g., metal) material, which may facilitate reducing the footprint and increasing the energy density of the secondary battery. The terminals and the busbars are typically thicker and heavier in weight than the tabs. The difference in thickness and weight between the tabs and the terminals and busbars presents manufacturing and cost challenges with respect to establishing and maintaining mutual electrical connection between the electrode and counter-electrode substructures and the respective terminal. For example, during production, the tabs may be connected to the terminal or busbar by gluing, welding, soldering, and the like, and the difference in thickness and weight makes it difficult to create a reliable connection. The connection between the tabs and the terminal or busbar are also susceptible to damage post-production due to impacts or material fatigue. The failure of such connection between one or more of the tabs and the terminal or busbar may cause deteriorated performance (e.g., lower energy and power density and/or lower battery capacity) or failure of the battery. [0006] Thus, a need exists for three-dimensional secondary batteries that include an improved interconnect design of battery components to address the challenges presented in three-dimensional secondary batteries and to facilitate improving manufacturing yield, reliability, and/or performance of the batteries. BRIEF DESCRIPTION [0007] One aspect is an electrode assembly for use with a secondary battery. The electrod