Industry Review of xEV Battery Size Standards
This Technical Information Report (TIR) will review the global industry battery size standards for xEV vehicles to provide guidance on available cell sizes for engineers developing battery powered vehicles. The TIR will include a review of the sizes and standards that are currently being developed or used for cylindrical cells, pouch (or polymer) cells, and for prismatic can cells. The lithium-ion cell will be the focus of this survey, but module and pack level size standards, where available, will also be included.
This SAE Battery Size Standardization Technical Information Report is intended to provide comprehensive reference and background information pertaining to battery size standards for xEV vehicles in the global industry.
With the introduction of the lithium-ion battery cell in 1991 the portable power industry quickly consolidated to a common form factor based with an 18 mm diameter and a 65 mm height, today referred to as an 18650 cell. This remained the de-facto industry standard cell size for portable power applications until the advent of the “pouch” or “polymer” cell in the late 1990s. Due to the relative flexibility of the pouch manufacturing process many different sizes of cells were introduced ranging from small milli ampere-hour size cells up to cells with over 100 ampere-hours in capacity. In the late 1990s the prismatic hard packaged can cell was also introduced and is being used in many xEV products in many different sizes.
OEMs and system integrators have long espoused the value and need for developing a set of standard cell sizes in order to create multiple sources for cells and to help the battery industry drive down costs by increasing volumes. With different vehicle architectures, different applications, different markets and uses, and different philosophies vehicle manufacturers have wide variations in their requirements that drive different types of cells and mechanical design solutions. However, by using standard cells in their designs they are able to drive increased volumes across many cell suppliers which is one of the major drivers for cost reduction in lithium-ion cell manufacturing.
Today there are several organizations that have already begun developing battery size standards across the world, including the International Organization for Standardization (ISO), the Standardization Administration of China (SAC), the Verband der Automobilindustrie (VDA), and Deutsches Institut für Normung (DIN), and SAE International (SAE) are just a few of the organizations that are working on cell level standards. There are many similarities in these standards but they are also largely driven by the local automobile manufacturer’s and regional government requirements.
As a next step after the completion of this report SAE would envision coordinating with these global standards groups to create specific set standards for the different on-road vehicles including Low Speed Electric Vehicles (LSEV), Automobiles, Buses, Heavy Duty and Commerical vehicles.