Each cell is bigger, so more energy can be stored in each cell, but pack space in vehicle remains the same, so number of cells goes down. Some manufacturers have been use large prismatic cell formats from the start. Bigger cells don't directly give increased range. Assuming other factors are equal, more active cell material in a pack gives more range.
Effectively, Tesla is migrating from laptop type small format cylindrical cells (18650 in MS and MX) to larger format cells (21700 in Model 3/Y) to even larger 46800s (guessing for Roadster 2.0, Semi, Cybertruck). Fewer, larger, cells can allow for better space utilization efficiency as less volume is used for cases and dead space between cells. Cooling capacity may suffer. Range improves as a result of better space utilization efficiency, lower weight from more efficient packing, and also cell energy density improvements. On Wed, Sep 23, 2020, 09:28 Peri Hartman via EV <[email protected]> wrote: > Lots of news today on tesla's battery day. Here's one excerpt from > wired: > https://www.wired.com/story/where-was-the-battery-at-teslas-battery-day/ > > Based on the digital mockups shown at the event, the new 4680 cell is a > lot different from the lithium-ion cells currently used in Teslas... The > diameter of the cylindrical cell is twice as wide, and it is 14 percent > longer than the largest batteries [tesla uses]. Altogether, that makes > its volume about six times greater... the larger form factor alone was > enough to boost the energy by five times, the power by six times, and > the range of a car using these batteries by 16 percent. > > Also some talk about removing cathode and anode tabs: > > But these tabs hobble the performance of the cells and make them more > difficult to produce. Manufacturers must use a specialized welding > technique to connect them to the foil current collectors, which results > in wasted time and material. Even worse, the tabs reduce the battery’s > efficiency, because electric current must travel the full length of the > electrode to reach each tab. ...the company laser-patterned existing > foil current collectors so that they can have dozens of connections to > the electrode materials. The result is a current collector that Baglino > described as a “shingled spiral” that looks a bit like a curled-up, > copper-plated armadillo. “The distance the electron has to travel is > much less,” Musk said. > > And some talk about using silicone instead of graphite to increase > energy density by 20-40%. Apparently, that isn't "new" news. Tesla > claims to have a new way to incorporate silicon that doesn't expand over > time. Also eliminate cobalt. > > -------- > > So, I guess the "tabless" statement is the main takeaway - a more > efficient cell with basically the same chemistry. The first statement is > confusing to me: how can you have 5 times the energy but only gain 16% > in range ? It could be that the form factor, itself, increases the range > by 16% and the other numbers relate to the increases from all the other > changes taken together. > > Wall street apparently expected more from all the hype over the last > several months. But, all in all, if Tesla can build what it announce, it > does sound pretty significant. While Tesla typically misses its > deadlines, it typically doesn't fail on meeting its goals. > > Peri > > > > << Want to know about the effects of leaf blowers ? > https://quietcleanseattle.org/ >> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200923/0d087a58/attachment.html > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/index.html > INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200923/fa341fee/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
