In the world of lithium-ion batteries, two of the most widely used formats are the 18650 and 21700 cells. Both are cylindrical in shape and have been staples in industries ranging from consumer electronics to electric vehicles (EVs). However, with advancements in battery technology, the debate over which battery is better—18650 or 21700—has become increasingly relevant. This article explores the differences, advantages, and use cases of these two popular battery formats to help you decide which is the better choice for your needs.