Meaning
Mass loss of a specific low viscosity solvent through the battery seal characterizes a common aging mechanism in lithium-ion cells. Continued dimethyl carbonate effusion leads to an increase in electrolyte concentration, which can elevate internal resistance. The process occurs when the internal vapor pressure of the cell exceeds the ambient pressure and the sealing material permits molecular passage.
Vapor Pressure
High volatility makes this particular carbonate more susceptible to escape than heavier molecules like ethylene carbonate. As internal temperatures rise, dimethyl carbonate effusion accelerates because the kinetic energy of the molecules increases the probability of permeation through the gasket. This physical property necessitates the use of high barrier polymers in the construction of the cell seal.
Concentration Impact
Chemical balance within the cell shifts as the ratio of salt to solvent changes. Since dimethyl carbonate effusion preferentially removes the thinner component, the electrolyte becomes increasingly viscous. This change hinders the movement of ions between the electrodes, resulting in a measurable drop in power density at low temperatures.
Containment Strategy
Advanced sealing technologies employ laser welding or specialized crimp designs to minimize gas loss. Rigorous testing for dimethyl carbonate effusion involves mass loss measurements over several months in controlled environmental chambers.
