At the much anticipated Tesla (NASDAQ: TSLA) Battery Day, Elon Musk promised to deliver a "compelling" $25,000 electric car within three years. Tesla’s CEO added that cars with internal-combustion engines will soon become a part of history.

Moreover, Musk said that his company plans to eliminate the use of cobalt in its cathodes. As for the investment in factories, Musk aims to slash costs by 75% in investment for those facilities.

"This presentation is about accelerating the time to sustainable energy," said Musk.

Here are the key takeaway messages from Tesla’s Battery Day:

• Arguably the loudest message delivered at the event is a promise to build a $25,000 electric vehicle within three years. In order to do so, new vehicles will have 370 fewer parts in the cars, which will then result in a 56% plunge in price per kilowatt-hour and a production cost drop of 69%. The long-term goal is to have 20 million vehicles per year made.
• Musk’s Tesla is working to cut costs at the cell level. The newly-built 4680 cells are easier to produce as they have fewer parts. They also have a shorter electrical path length to reduce heat. As a result, the new cell produces five times the energy, six times the power and 16% more range.
• New cells will be built in a pilot gigawatt factory in California. While the ultimate goal is to reach 200 gigawatt-hours production, the electric car maker will need a year to reach the 10-gigawatt-hour capacity. "We're not saying this is completely in the bag. There's still a lot of work to do," Musk said.
• Overall, the aim is to have batteries produced at 100 gigawatt-hours by 2022 and 3 terawatt-hours by 2030.
• Tesla is working to completely remove cobalt from its cathodes. Instead, it will use nickel. The nickel battery costs 15% less than the cobalt one, per dollar cost.
• As a part of the cell production plant, Tesla will build its own cathode facility in the United States. The aim here is to cut costs by 75% for cathode development, as well as having a more environment-friendly process by using zero wastewater.
• Tesla also started its own in-house pilot project in Nevada to recycle Tesla products. It currently uses the services of third parties in this process.
• The electric car maker announced that the Plaid Model S, the newest variant to the company's flagship sedan, is available to order and will be rolled out before the end of next year.

Tesla stock is trading down 5% lower in premarket trading possibly on a 'sell the news' trade and unit growth guidance that was roughly in line with the Street.

Commenting on the event, Wedbush analyst Dan Ives said: "This was a massively hyped event for Musk and Tesla and the battery production cost targets were staggering, which if achieved would be a potential game changer for the company's cost structure and price points going forward. The stock is down on knee jerk reaction as the biggest disappointment of the event from the Street's perspective was around no million mile battery announcement in our opinion as this was widely expected to be unveiled. That said, hitting below the $100/kWh threshold remains a foundational goal that could set apart Tesla further from EV competitors down the road. Overall, Tesla gave some aggressive targets and goals which were impressive and sets the goal posts for the next few years on the battery and cost structure front."