Single-string cylindrical lithium battery assembly

This paper investigates 19 Li-ion cylindrical battery cells from four cell manufacturers in four formats (18650, 20700, 21700, and 4680). We aim to systematically capture the design features, such as tab design and quality parameters, such as manufacturing tolerances and generically describe cylindrical cells.

Known for their reliability, efficiency, and versatility, cylindrical batteries have become a critical component in grid-scale battery energy storage systems (BESS). What sets these cells apart from other battery types is their rigid cylindrical structure, which enables efficient packing and cooling.

A generic overview of designing cylindrical Li-ion battery cells. Function 1: Two types of jelly roll designs can be distinguished: With tabs and tabless. Jelly rolls with tabs can be realized with a single tab (Design A) or several tabs in a multi-tab design (Design B).

The manufacture of the lithium-ion battery cell comprises the three main process steps of electrode manufacturing, cell assembly and cell finishing. The electrode manufacturing and cell finishing process steps are largely independent of the cell type, while cell assembly distinguishes between pouch and cylindrical cells as well as prismatic cells.

Cylindrical Li-ion battery cells consist of (i) a jelly roll, a wound composite consisting of a cathode, an anode, and two separators, and (ii) a cell housing consisting of a can and a cap . Current and heat transport between the jelly roll and the cell housing is traditionally conducted by contacting elements called tabs .

In the last 3 years, cylindrical cells have gained strong relevance and popularity among automotive manufacturers, mainly driven by innovative cell designs, such as the Tesla tabless design. This paper investigates 19 Li-ion cylindrical battery cells from four cell manufacturers in four formats (18650, 20700, 21700, and 4680).