During Tesla’s long-awaited Battery Day, CEO Elon Musk showcased a number of new technologies the automaker is working on, but as expected all seem to be somewhat far on the horizon.
One of the most talked about pieces of battery tech in the weeks leading up to the event was Tesla’s intent to manufacture tabless battery cells using use a newly-patented method, thereby using fewer parts inside each battery pack. The automaker refers to this new type of cell as the 4680 cell, for the 46 millimeter by 80 millimeter cell dimensions, and plans to produce them in-house as expected.
The company uses 2170 cells today, manufactured by Panasonic in the automaker’s Gigafactory plant, which are used in the Model Y and the Model 3. The Tesla CEO suggested that experimental production is somewhat close to operating at the pilot plant level, but did not say just when he expects Tesla to be able to switch to these new type of cells even on a limited basis.
The new cells promise to be lighterfive-times more energy storage capacity and 14% cheaper cost per kilowatt hour to produce. The cells are also promised to be six-times more powerful when it comes to power capacity. The benefit for car buyers will be greater range — 16 percent by Tesla’s estimate — and a lower vehicle price. About the only parameter Tesla did not share about the new battery type is the energy density.
Earlier this year Tesla filed a patent for this type of battery cell, explaining its structure.
“A cell of an energy storage device with at least one electrode that is tabless, and methods of forming thereof, are described,” the patent application states. “The cell includes a first substrate having a first coating disposed thereon, wherein a second portion of the first substrate at a proximal end along the width of the first substrate comprises a conductive material. An inner separator is disposed over the first substrate. A second substrate is disposed over the inner separator. The second substrate has a second coating disposed thereon. The first substrate, the inner separator, and the second substrate in a successive manner, the first substrate, the inner separator, and the second substrate are rolled about a central axis.”
The automaker also explained in the patent application why today’s method of cell manufacturing is not as cost effective as it could be.
“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 automaker said in the patent filing earlier this year. “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, they increase costs and present manufacturing challenges.”
Of course, the assembly of these cells is by no means imminent, as Tesla first has to create a new assembly line for them. As industry watchers predicted, this wouldn’t happen for some time because Tesla needs greater floorspace in Fremont to actually produce these for its cars, and would need to refit a separate factory for this purpose. So the new 4680 cells won’t benefit Tesla vehicles for some time.
So when might we see the 4680 cells in production Tesla vehicles?
Musk indicated they’re about three years away, actually putting them beyond the starting dates for the production of several new Tesla models. The Cybertruck is planned to enter production in late 2021, about the same time as the Tesla Semi. Both of these models, at least according to Tesla estimates, are expected to outpace the start of mass production of the tabless battery.