SMM9 March 23: today, Tesla's "Battery Day" activity ended. At this event, Musk proposed multiple innovations in battery technology. For example, Tesla will directly build the battery into the car structure, reducing the cost per kilowatt hour by 7%. Tesla will use 100% nickel batteries in energy-intensive models. These innovations will effectively reduce battery manufacturing costs and improve battery life and power.

Although Tesla's shares rose nearly 5 per cent in after-hours trading at the start of the battery day, Tesla's shares fell more than 5 per cent by the close. Tesla's share price fell either because Musk did not mention the previously closely watched "million-mile battery" in Battery Day, and the daily performance of the battery fell short of market expectations.

The main battery technologies are as follows:

Negative electrode material of silicon nanowire battery

Tesla released the registration page for battery day activities on Sept. 19. The background picture on the page is the structure diagram of silicon nanowires, a new battery material. As a known technology, silicon nanowires can reduce the weight and volume of batteries, thereby improving battery efficiency and helping to make batteries with higher energy density and longer service life.

However, the overall industrialization of silicon-based negative electrode is low, so it is expensive, which is much higher than that of graphite anode material. According to Warburg Securities, the market price of silicon-based anode materials with 420-450mAh/g capacity (a mixture of silicon-based materials and graphite) is between 11 and 150000 per tonne, with a median value of about 120000 per tonne, while the price of high-end graphite is only 70, 000 to 80, 000 per tonne. In addition, the processing route of silicon-based rice noodles is complex, which is generally coated by nano-materials or prepared with special structure of nano-materials, which is much more difficult than the manufacture of graphite negative electrode.

At present, Tesla Model3 has all used silicon-carbon negative electrode as the negative material of its power battery, and in the future, other middle and high-end series will also convert the system one after another, which will drive global power battery manufacturers to speed up the research and development and introduction of silicon-carbon negative electrode. The agency believes that the silicon-carbon negative electrode has a very high theoretical capacity and is a necessary link in the development route of power batteries. With the continuous progress of new energy vehicle technology and the improvement of downstream demand, the permeability of silicon-carbon materials in the negative materials of power batteries will reach 40% in 2022.

Electrodeless ear battery

Musk said that the size of Tesla's battery has increased from 1865 to 2170 (the first two digits are diameter and the last two digits are length) and will now increase to "4680". The new "4680 battery" will take about a year to reach 1 gigawatt of capacity, but Tesla is considering increasing it to 2 gigawatts a year. The change in appearance alone can reduce the cost per kilowatt-hour by 14%, but Tesla has not yet done so. The design of the electrodeless ear will make the travel path of the electron shorter, solving one of the biggest problems of increasing the diameter of the battery. This makes the battery module easier, faster and continuously produced. The energy of the new "4680" battery is increased by 5 times, the mileage is increased by 16%, and the power is increased by 6 times. At the same time, due to solving the problem of continuous production, the speed of Tesla battery production line is increased 7 times.

Currently, 4680 batteries will be produced on the plant's new assembly line, with annual production planned to reach 10GWh by the end of 2021. However, Musk also admitted that the design and manufacturing process of the new battery has not yet been fully completed and that it will take three years for the new battery to go into full production.

Battery built-in car structure

Musk said the battery would be built directly into the car structure, an innovation inspired by the fuel tank on the wing of the aircraft. The structural battery will reduce the overall weight of the vehicle. This will reduce the total number of parts required (by 370 parts) and speed up production. And most importantly, it will reduce the cost per kilowatt-hour by 7%.

100% nickel battery

Musk announced that they would switch from the "cobalt" model to the "nickel" model, and the company was developing a cobalt-free, nickel-rich cathode by using a "new coating", but the company did not say how close it was to achieve that goal. nor did it elaborate on the use of these coatings. In the energy-intensive model (Cybertruck/Semi), Tesla will use 100% nickel support, while other models will use a combination of nickel and other chemicals. This ensures that mass production is possible. Musk reiterated that he wants more people to mine nickel.

According to SMM, the 100% nickel battery mentioned by Musk did not specify when it would overcome technical difficulties to achieve mass production, in addition to the instability caused by cobalt-free batteries, and the possible production of lithium nickel manganate materials from 2x3 nickel and 1gram 3mn did not mention how to solve the related safety problems. It is foreseeable that Tesla will still develop in the direction of high nickel and low cobalt in the future, or use Ni88, Ni90 or NCMA batteries next year. With regard to the large battery, the battery day did not mention the specific materials used in the battery, or it is still mainly ternary, mainly through the electrodeless ear technology to increase the cell diameter, the actual energy density of the single cell has not changed much. However, this technology may lead battery companies to change battery specifications and models, or lead the way of power battery technology in the future. Overall, the conference announced a variety of lithium battery development routes, but also saw a variety of possibilities for future batteries, whether these technologies can be commercialized remains to be tested in the future.