Tesla Battery Day

Tesla held its 2020 shareholder meeting where it also announced progress and plans regarding its battery production. Historically it used off the shelve batteries, then it started to make its own in cooperation with Samsung, and now it makes them in house doing research on every aspect of the production chain. The aim is to find a method to produce TerraWathours of batteries ASAP because batteries are the limiting factor to the adoption of Electric Vehicles.

The innovations and improvements are amongst others

A new way to make batteries that have multiple tabs, or [single] tabless. The advantage is in the production speed, the tab doesn’t need to be attached, but also in output power, as now the path between electrode and the output is shorter and has less resistance.

In a ‘tabless’ battery the entire side of the membrane is a tab, so electrons can leave the membrane much easier. The trick was to make a cut copper strip that could be auotmatically folded inwards without shorting the battery.

Tesla will use Silicon as an electrode, and developed a method to encapsulate this brittle metal in such a way that it does not crumble and lose contact on charging and discharging. They will encapsulate the silicon in a conducting polymer. Silicon is a much better absorber of lithium than grafite.

Tesla has looked at the raw materials processing and redesigned it to its bare minimal steps. Industry prepares their materials for general trade, but Tesla has a specific use for it and has rethought it. This saves a lot of cost, logistics and pollution. This also reduces the size of the factory as a lot of work went into making the paste and recycling the water.

Tesla wants to create different batteries for different purposes, so that the high nickel high energy batteries can be used in semi-trucks and the low energy density lower nickel ones in stationary storage or low end cars.

The mining and processing of Nickel can be a lot simpler

Batteries consistes of layers separated by a membrane. Ions move from one side to the other as the batteries are charged and discharged. The preparation of these layers has been done in a wet proces, as a paste that gets sintered. Tesla plans to change this to a dry proces that gets pressed onto the substrate.

A dry paste is pressed in to a film

Last but not least Tesla has introduced a new method of constructing the base carriage of the car. The new batteries (their cilindrical casings) will become a structual part of the car, providing stiffness with the weight more centered than before. To achieve this the basic buildup has three parts, a front a back and a battery pack in between.

Heat modelling of Tesla’s aluminium casting process

All these innovations and changes will cut the battery cost by 69% and will be realized in the next 3 years. Its great because a battery plant can be much smaller now, and will cost less. We would like to see every country with a couple of billions to spare to build a Tesla battery factory.