The latest document of Tesla's Berlin factory reveals the 4680 battery production process.

According to foreign media reports, the latest documents of Tesla's Berlin factory have been posted online, which is simply a treasure trove of information. The document provides some new details of the 4680 battery plant in the Berlin super factory and the production process of the 4680 battery.

Although the part of the document about the 4680 battery plant is blocked because of sensitive information, the document still reveals some important information. For example, battery production and operation is more than four floors, cathode and anode are produced on the first floor, and unlabeled cells are produced on the third floor. The battery plant is large and requires a large area of foundation similar to the Berlin Super Factory Phase I area.

More importantly, Tesla also submitted a simplified version of the 4680 battery production process diagram, and a brief overview of the production process:

"batteries in the Berlin super factory require special systems and processes. The anode and cathode are composed of collector foils covered with paint. The anode foil is made of copper and the cathode foil is made of aluminum. The anode and cathode components are manufactured by mixed process (A020-01, A020-02), in which only powdered materials are used. The new materials used were tested and approved in our own laboratory (A020-11).

In order for the powder coating to be bonded to the two layers of film, a thin layer of binder (matrix) (A020-03 and A020-04) must be pre-coated. This matrix is transmitted in a container. Pre-coating is necessary because it allows the powder to form a dry coating. After the anode and cathode materials are mixed, they are applied as coatings to their respective matrix coating films to establish electrical contact (A020-05 and A020-06). After that, the current collector foil is coated with an anode or cathode material to form a finished anode or cathode. "

The document also provides a general method for the production of Tesla's unlabeled cell, in which the finished 4680 cell will be solidified for 10 days after completion.

"then use a laser to cut the anode or cathode to the desired length in 'untagged processing' (A020-08). The anode, cathode and diaphragm are alternately placed and rolled into a roll and then inserted into the metal housing, which is made by steel rollers during die-cutting and deep drawing (A020-07). In the assembly area, the final assembly and filling battery is achieved using a small amount of electrolyte (about 10% of the battery weight) (A020-09).

The electrolyte is absorbed by the electrode coating so that the lithium ion can move back and forth between the anode and the cathode. Then, the lid is welded during the welding process. The last step is the formation of the core (A020-10). During the formation process, the battery starts electrically by charging and Discharge at different temperatures. The finished cell is kept in this area for about 10 days and then put into use. The cells produced will be subject to random quality control in our own laboratory (A020-11). "