Category: Energy Conversion and Storage
Subject: Types of Cell Construction
What are the various ways in which cells can be housed?
A key component of a cell is the case and there are three types:
- Prismatic metal case – prismatic Li-ion cells have high energy density. Metal cans are strong and enable good heat dissipation. These come in sizes up to 100 Ah.
- Cylindrical steel case – small cylindrical cells are made in very high volumes and the price is low for standard shapes. The 18650 (18 mm diameter, 650 mm long) standard size cells are used on laptop batteries. For the standard size cells the battery pack must be designed around the available cell. The cells have high energy density but the disadvantage is their bulky size and inefficient use of space. The air cavities created between cells can be used for cooling. The cells usually have an overcharge protection.
- Pouch cell – these make the most efficient use of available space and achieve a packaging efficiency of 90-95%. The pouch pack has a lower weight and therefore this will have a higher energy density due to the absence of a metal can. Pouch cells can be produced in different forms depending on the application and manufacturers are not bound by standard cell formats.
Answered by: Ming Chung
Affiliation: Johnson Matthey Technology Review