Why Tesla is Approaching Towards prismatic cell Lithium-Ion Battery
Prismatic cells use less space and synthesize more energy than cylindrical and pouch cells.
Prismatic cell
Prismatic cells differ from cylindrical and pouch cells due to their prismatic structure. The cells are sandwiched together into layers with the implementation of pressure in a prismatic structure. This packing of cells forms a box-like prismatic structure, and more space is utilized than conventional cylindrical cells. The prismatic cells are prepared with a variable range of ampere-hours according to the requirement. These cells consist of lengthy sheets of anodes and cathodes. Cells are pressed into cubic or rectangular shapes of hard plastic or metallic boxes with separators. There are two types of these cells: 1) Stacked prismatic cell and 2) Flattened prismatic cell. Prismatic cells are more cost-effective than cylindrical cells because of less space.
Lithium-Ion Batteries (LIBs) may consist of cylindrical, prismatic, and pouch cells. Prismatic cells in lithium-ion batteries have a separator separating the large sheet of anodes and a cathode. Cells are stacked with pressure into the metallic or plastic box. Lithium iron phosphate LFP (LiFePO4), a mixture, is widely used because of its low cost. There is no need for costly materials such as cobalt, manganese, and nickel to run these batteries. Hence, LFP is cheaper than composites containing these expensive metal particles. Because of its cost-effectiveness, LFP is attracting the attention of electric vehicle manufacturers in Asia, America, and Europe.
As the prismatic cells have a higher charge capacity, aluminum connectors are used to connect these cells. Aluminum is cost-saving, and current busbar collectors give more weight. Like the cylindrical and pouch cells, prismatic cells are joined between electrode foil and current collector tabs leading to the battery terminals. These current collector tabs and electrode foils are welded with laser or ultrasonic welding.
Furthermore, the design of the prismatic cells conserves the space. Four prismatic cells are connected in such a way to produce the 12V battery pack. These cells have more choices due to the rectangular shape and thin layers.
On the other hand, no standard prismatic cell is available to produce the other relevant cells. Manufacturer of the batteries has their design and shape. Prismatic cells in mobile contain different lengths, widths, and sizes. The laptop prismatic batteries manufacturer produces the batteries according to the space available. Electrical vehicle (EV) manufacturer have their shape and capacity for the prismatic cell.
Advantages
Though prismatic cells are less common than cylindrical cells, they have some advantages too. Their efficacy is more significant than cylindrical cells because of the smaller rectangular shape, which provides more power to the system. In the square-shaped battery, the internal resistance is better; hence, discharging of the cell is higher, which is strong proof to be used as high power for devices, for instance, electric bikes and cars. Due to their compactness, prismatic cells can be utilized in smaller devices. They do not swell or expand with movement or vibration; hence, they can be used in portable devices like cellular phones, laptops, etc. These batteries generate higher power, and these are durable. Better layering in a rectangular shape makes a better option for engineers to produce several designs of the prismatic cell. Prismatic cells remove the production steps involved, which enhances their cost. This enables the manufacturers to make the prismatic cells on a large scale.
Applications
Due to petroleum prices and combustion engine pollution, electric vehicle industries are evolving in the automobile market. These industries are using cylindrical and prismatic cells in EVs. These cells are widely used in electrical devices such as hybrid/electric vehicles, cell phones, Electrical boats, golf carts, power tools, UPS systems, e-bikes, solar systems, laptops, watches, etc. The energy obtained from wind, geothermal, solar, and other renewable sources can be stored in Li-ion batteries (LIBs) because of their high energy efficiency. Hence, different industries and government organizations have an interest in using LIBs.
Difference between cylindrical and prismatic cell
Prismatic cells tend to store more energy than cylindrical cells but have less power. Prismatic cells discharge more rapidly than cylindrical cells, enhancing the per ampere-hour capacity of the cell. Hence, prismatic cells are optimized for energy efficiency. Electric bike batteries are an excellent example of prismatic cells. Cylindrical cells are smaller than prismatic cells, and more cylindrical cells are required to gain the same energy. In this case, prismatic cells are better due to less welded connections. Twenty to hundred cylindrical cells produce energy equal to one prismatic cell. This is the reason for its wider use.
Difference between the pouch and prismatic cell
Prismatic cells are stacked onto one another and pressed into the plastic rectangular or cubic box with fewer connections. In contrast, pouch cells are attached to cathode and anode and separated by a separator. The pouch cells are lighter than prismatic cells. The light weight of the pouch cell is because of the soft coating of aluminum in the battery. The size of the pouch cell is adaptable similar to the prismatic cells. They can be manufactured according to the need of the gadget. This adaptability makes these cells more valuable for portable devices. This packing enhances the energy density and efficiency of the cells. Both these cells are being used in electrical devices. Pouch cells have some limitations, too — pouch cell structure lack standardization which increases its production cost and selling price. Also, pouch cells show lower mechanical resistance, and with time, potential expansion is found in the cells due to gas formation.
In the first electric vehicle of, Tesla, the battery cells used were cylindrical. The number of cells was more significant to meet the energy need at a reasonable cost. Tesla bought cylindrical cells from Panasonic to make up more energy with less cost using cheap cylindrical batteries. These cells require a lot of connection with the quality of the battery management system. Elon Musk (The founder of the Tesla company) said he would utilize the prismatic cells in the upcoming electric vehicles. Tesla company wants to change the battery setup in the coming years.
