Image: Tesla patent
In September 2020, Tesla held Battery Day, where it presented its new development—the larger 4680 battery cell. The new development required use of new methods and technologies. Tesla has published the patent: "Energy storage cell" for its cylindrical 4680 battery cell.
Electric vehicles may be fully or partially powered by a battery, which may be individual battery cells or cells, modules and blocks. Electric vehicles typically require a large multiple of power — a thousand times stronger than that of a typical consumer product, such as a mobile device. To achieve these power requirements, the battery pack of electric vehicles typically includes a large, dense arrangement of individual cells, individually placed or configured into a plurality of modules.
The patent, filed September 21, 2021, and published March 24, 2022, describes cylindrical battery cells. Each of the elements includes: a top surface having a center terminal and an outer terminal, where the first terminal and the second terminal are configured as electrical contacts; a side surface mechanically connected to the top surface; a bottom surface mechanically connected to the side surface; and an energy storage material within the top surface, the side surface, and the bottom surface, where the cells are interconnected by laser welds and aligned in a substantially planar configuration.
The generally described invention relates to an energy storage cell that is designed for integration into large-scale vehicle and grid storage products. Illustratively, to support such integration, individual energy storage cells can correspond to cylindrical-shaped storage cells of various volumes and aspect ratios. The cylindrical storage cells have specific characteristics or configurations that further support integration.
More specifically, in one aspect, the cylindrical storage cells include a top surface that is configured specifically to present concentric and substantially co-planar positive and negative terminals such that the surface area for welding interconnects offers statistically balanced outcomes between positive and negative terminals. In a related aspect, the center terminal interface (be it positive or negative) may be elevated relative to the surrounding geometry, including the other terminal, the terminal insulator gasket which serves as an electrical insulator between the two terminals, or another element of the cell canister. In another aspect, the cylindrical storage cells include a side surface that is sleeved to electrically isolate individual cells from each other and ancillary components in a cell array. Additionally, the side surface illustratively functions to interface with cooling systems added as part of the cell array, serving as the primary conduit for extracting heat generated within individual cells. In still another aspect, the cylindrical storage cell design includes a bottom surface that selectively groups cell features or functionalities that, in the prior art, may require incorporation into either the top surface or side surface. Such additional features can include geometry for sealing of the open end of a drawn or extruded cell can, geometry for calibrated venting in thermal runaway, inputs for receiving material into the storage cell, and the like.
The Tesla patent reads that cell form factor selection offers efficient and effective leverage on the resulting performance, cost, package volume, durability, and manufacturing efficiency of a battery pack. The cylindrical format offers decisive benefits in cost/manufacturing efficiency, via single-piece continuous motion assembly processes, and packaging/durability, via internally resolved stack electrode material expansion forces. Cylindrical formats also generally yield improvements in performance, via shorter thermal path lengths, and volumetric energy density, via wrapped geometry of the electrode stack.
FIG. 1A illustrates an example energy storage cell in a sleeve.
FIG. IB illustrates a perspective view of an example energy storage cell.
© 2022, Eva Fox | Tesmanian. All rights reserved.
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About the Author
Eva Fox joined Tesmanian in 2019 to cover breaking news as an automotive journalist. The main topics that she covers are clean energy and electric vehicles. As a journalist, Eva is specialized in Tesla and topics related to the work and development of the company.