Tesla Battery Day: What to expect and how to stream the event - Roadshow

As we approach Tesla's Battery Day, scheduled for Tuesday, we've already heard a lot about what could make an appearance at CEO Elon Musk's next big event. While we probably won't learn much about Tesla cars specifically, there could be news on breakthrough technology for the batteries that power them -- or perhaps the company's intentions to expand further into the energy-storage business.

We decided to round up all the rumors we've heard in one place. We're updating this as we hear more. And if you want to watch all the action unfold, head to the link here as the presentation kicks off at 4:30 p.m. ET/1:30 p.m. PT.

A Tesla 'Biscuit Tin?'

On Wednesday, photos of a potential new battery cell Tesla plans to build itself showed up on the internet. Simon Moores, managing director of Benchmark Mineral, a price reporting agency for the lithium-ion battery industry, dubbed it the "Biscuit Tin," because that's what it looks like. Electrek first reported on leaked photos apparently showing this new battery cell, which is chunkier and can supposedly pack more energy density per cell. In the grand scheme of things, more energy per cell means fewer cells per pack, which can unlock big cost savings. The photos also appear to show a tabless design to create a more efficient manufacturing process.

Silicon nanowire anode for a Tesla battery

What the heck is a silicon nanowire anode? Tesla sent out its Battery Day invite, above, with a peculiar pattern of dots and clustered lines, which led experts to surmise we're looking at a teaser for the technology. It's a potentially massive breakthrough for batteries, and it seems like the most likely piece of news we'll get from Battery Day so far. Musk is pretty unpredictable, so who knows? We could get something even more interesting in the weeks to come.

The technology could allow Tesla and its battery partners to produce units with far more energy density (meaning longer ranges) and a longer usable life. Batteries with more energy that last longer are the golden key to unlocking more affordable electric cars.

Musk teases potential manufacturing 'redesign'

Battery Day might be all about the batteries, but Musk also teased that we could see big news on the vehicle manufacturing side as well. According to Electrek, Musk plans to talk about how Tesla plans to build cars at its upcoming European Gigafactory in Berlin. There, the CEO said the facility will be home to a "radical redesign of the core technology of building a car." He added Battery Day will include "some of what [Tesla is] going to be doing in Berlin."

What specifically Tesla has up its sleeve, we don't know. But Musk ended his recent comments while touring the construction site by saying, "It is going to be the first time that there will be a transformation of the core structural design of the vehicle."

A roadmap to a 400 watt-hour battery

Musk took to Twitter last month to comment on a rumor Tesla's actually interested in an electric airplane. We won't dive into that since we have zero evidence to support the theory, but what Musk said is intriguing on its own. He spoke about the ability to mass-produce batteries with 400 watt-hours per kilogram may come within the next three to four years. In the past, Musk said this is the threshold for electric aircraft to become viable.

But, airplanes aside, that kind of energy density would be unreal by today's standards. For comparison, the Tesla Model 3 hits about 260 Wh/kg. Imagine a Model 3 with 50% more energy density and you'll understand why anything Musk announces involving this goal is a very big deal.

Musk hints at big changes coming, but not until 2022

Musk took to Twitter Monday to caution people from getting too excited over Tuesday's Battery Day announcements. While he claims it will mean big changes for Semi, Roadster and Cybertruck, those changes will take a couple of years to reach full-scale production.

The million-mile battery

This particular item's been swirling around the rumor mill for almost a year now, and if Tesla has something to say about it, Battery Day sure seems like the proper time. China's Contemporary Amperex Technology Limited already confirmed it has a unit prepared to run 1.24 million miles, and it just so happens CATL is a battery supplier of Tesla's. The automaker hasn't made anything official surrounding the battery, however.

It could be that Tesla has something else better tailored for its current and upcoming vehicles, or perhaps CATL's unit is totally unrelated. At a minimum, we know Tesla has worked with researchers to pave the way for a million-mile battery in the past.

Goodbye to cobalt batteries?

While CATL confirmed it has a million-mile battery ready for production, the company went a step further to confirm reports it's worked with Tesla to develop cobalt-free batteries. Cobalt remains a highly controversial rare earth material due to the political and humanitarian circumstances surrounding its mining. It's also quite expensive.

Instead, rumors suggest CATL and Tesla focused on lithium-iron phosphate batteries, specifically for China to start. Reportedly, the two have been in talks to use the battery firm's "cell-to-pack" technology to make up for a lack of cobalt, which helps increase energy density and improve ranges. We don't have the full story on this development, so we may learn a lot more about Tesla's use of cobalt at Battery Day.

Musk and Tesla's electricity utility aspirations

On two occasions we've learned of Tesla's interest in electricity utility doings over in Europe. Perhaps Battery Day will shed some light on what Tesla may have planned. Earlier this year, Tesla applied for a utility license in the UK, and earlier this week, we learned the automaker received a license to distribute electricity in western Europe. Not only that, but Tesla also sent a survey to current owners in Germany feeling out what would prompt them to switch from their current energy provider. The automaker queried owners further and asked if they'd purchase a PowerWall and even allow Tesla to control when they can charge their EV.

It all ties into Tesla's Autobidder program, which currently runs at its Australian battery farm. Essentially, it allows those involved to sell energy back to the grid when they don't need it. Experts don't think Tesla would break into the utility business on its own, but instead work with partners in various countries to capitalize on balancing the grid at large with batteries.

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First published Sept. 3.