1. First of all, make a conceptual clarification: Stacked battery vs. polymer battery vs. polymer battery. Bags of battery
The problem mentioned "Laminated (Polymer) lithium ion battery", please note that Laminated (Laminated) battery and Polymer (Polymer) battery are two different concepts. Polymer batteries are those that contain a polymer or colloidal electrolyte, which is dissolved in a liquid electrolyte in a conventional lithium-ion battery. The so-called stacked battery refers to the internal electrode and diaphragm are stacked on top of each other, which corresponds to the winding cell of the winding battery (18650 battery is the winding battery). Generally, polymer batteries are stacked, so they can also be called stacked batteries. However, because cascade batteries can also use liquid electrolytes, cascade lithium-ion batteries may not be polymer lithium-ion batteries. In fact, most of the stacked power cells used in electric cars (Nissan LEAF, GM Volt, etc.) are liquid electrolytes. This confusion may be due to the fact that cascading and polymer cells are typically packaged in an aluminum-plastic membrane, also known as a "Pouch." It is possible, however, to have a winding cell inside a bag battery.
Polymer batteries don't seem to be in use in electric cars right now, and I suspect the main reason is that colloidal electrolytes don't conduct electricity very well and therefore have high internal resistance.
2. Why does Tesla use 18650 battery?
What are the advantages of Tesla's battery management system (BMS) over other electric vehicles? There are several reasons mentioned in ", which are discussed here.
A. consistency
The 18650 battery is the earliest, most mature and most stable lithium-ion battery. It is widely used in electronic products, and about billions of batteries are shipped every year. Over the years, Japanese manufacturers have accumulated a lot of experience in the production process of 18650 battery, which makes the consistency and safety of the produced 18650 battery reach a very high level.
In a battery world professor exchanges with the United States, in the process he half jokingly said: if you purchased directly from a Japanese manufacturer the same batch of battery, then use your battery charging and discharging test instrument to test them at the same time, if it is found that different channel to measure the discharge curve is different, you should suspect that your equipment rather than the consistency of the battery.
In contrast, the stacked lithium-ion battery is far from mature, and even the size, size and pole lug position are not uniform. Battery manufacturers also lack experience, and the consistency of the battery cannot reach the level of 18650 battery. If the consistency of the battery is not up to the requirements, the management of a large number of battery strings and parallel batteries will be a nightmare.
