Image: Tesla patent
Tesla published the patent "Tabless energy storage devices and methods of manufacturing thereof," which refers to energy storage devices and methods for their manufacture. It describes the cells of a battery named 4680 with tabless cathodes and anodes and methods for making it.
Many types of battery cells are currently used as power sources in electric vehicles and energy storage devices. Many current cells use a jelly-roll design in which the cathode, anode, and separators are rolled together and have a cathode tab and an anode tab to connect to the positive and negative terminals of the cell can. The path of the current necessarily travels through these tabs to connectors on the outside of the battery cell. However, ohmic resistance is increased with distance when current must travel all the way along the cathode or anode to the tab and out of the cell. Furthermore, because the tabs are additional components, add additional thickness to the device, and must themselves be rolled into the jellyroll, they increase costs and present manufacturing challenges.
During Battery Day in 2020, Tesla unveiled the new 4680 battery cell, which is built in a new way. The patent "Tabless energy storage devices and methods of manufacturing thereof," filed on September 17, 2021, and published on March 24, 2022, describes how it is manufactured. In particular, it talks about a method of making a battery cell comprising an anode or a cathode having a series of flags formed from the foil portions at the upper and lower ends of each electrode, where the flags are folded over at each end to form an interleaved flower shape.
In addition, the patent talks about providing an electrode layer having an active material disposed over a foil; forming a series of flags in the foil to form a flagged electrode; winding the flagged electrode to form an electrode roll comprising a series of rolled flags; and electrically connecting the rolled flags to a current collector to form an energy storage device.
In another aspect, a method of preparing a rolled electrode is described. The method includes providing an electrode layer comprising an active material disposed over a foil; forming a series of flags in the foil to form a flagged electrode; folding the flags to produce a folded flagged electrode comprising a series of folded flags; and winding the folded flagged electrode to form an electrode roll, where as the folded flags are wound each flag of the folded flags is directed into a substantially interleaved configuration.
In another aspect, an interleaved flagged electrode is described. The electrode includes a wound flagged electrode layer comprising an active material disposed over a foil; where the foil comprises a series of flags; and while each of the series of flags are folded and in a substantially interleaved configuration.
Tesla is aiming to make battery cells, the most expensive part of any electric vehicle, as cheap as possible. Cheaper batteries will make EVs affordable to more people, which means the world will move faster away from cars with internal combustion engines that pollute the environment and negatively affect the world's climate.
© 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.