[Science articles] 'Cylinder, square, soft package' technical route

As we all know, power batteries are the core technology of electric vehicles. Compared with traditional lead-acid batteries and nickel-metal hydride batteries, lithium-ion batteries are the main development direction of current power batteries because of their high specific energy, high specific power, easy realization of rapid charging and deep discharge, and long life.

In fact, these performances of lithium-ion batteries are closely related to their packaging forms. In this article, we will explain in detail the packaging forms of lithium-ion batteries and look at the advantages and disadvantages of different technical routes.

'Tripod'

According to the different shells of the battery cells, lithium-ion batteries are divided into two types: hard shell and soft case class. The hard shell materials mainly include steel shell and aluminum shell, while the soft shell uses aluminum-plastic composite film material. Among them, the hard shell is divided into cylindrical and square according to the arrangement of the positive and negative plates inside. As shown in the figure below:

From this, we can get the three packaging forms of the current mainstream lithium-ion batteries, namely cylindrical (cylindrical), square (prismatic), and soft package ( pouch, also called polymer battery in some places).

'Each has its own merits'

Below we use a picture to show the advantages and disadvantages of different packaging forms:

To sum up briefly, cylindrical batteries, because of their mature technology and favored by Tesla, have always attracted attention; prismatic batteries, because of their safety, are also the mainstream technical route. One: The development of soft-pack batteries has benefited from the development trend of consumer electronics towards smaller, lighter and thinner.

'The true face of Lushan'

In fact, the different packaging forms of lithium-ion batteries are determined by the manufacturing process of their cells Decided:

The three manufacturing processes correspond to the three configurations of lithium-ion batteries, the cylindrical winding type corresponds to 'cylindrical'Pouch' (pouch), the square winding type corresponds to 'prismatic'. After reading the picture above, I believe everyone will understand the origin of the name 'cylindrical, square and pouch'.

Let’s take a look at the real objects and see what they all look like:

Since the three forms have their own characteristics, So how do the major OEMs choose?