Coulombic Efficiency (CE) is the ratio of the total charge that can be discharged from a battery to the total charge that was put into it during the previous charge, typically expressed as a percentage. In other words, if you charge a battery with X coulombs of charge and you can get Y coulombs out in the subsequent discharge, the CE is Y/X * 100%. An ideal battery with no losses would have a CE of 100%. After the initial formation cycles, the CE in typical commercial lithium-ion batteries is >99.9% per cycle until the battery approaches end of life. CE is less than 100% because some charge is lost to side reactions like electrolyte decomposition, lithium plating, etc. Coulombic efficiency is a crucial measure for battery health and estimating end of battery life.
NOVONIX is a pioneer in measuring coulombic efficiency using their Ultra-Hich Precision Coulometry testing equipment. By using UHPC tools, NOVONIX can accurately detect differences in CE beyond the fourth decimal place. This allows them to observe very subtle effects of new materials or additives on battery life. For instance, if an electrolyte additive improves CE from 99.90% to 99.95%, NOVONIX’s equipment can reliably measure that improvement in very early cycles, unlike conventional battery testing equipment. The improvement in CE might translate to significantly longer cycle life.
