Meaning
Charge carrier movement through the electrolyte and electrode interfaces at temperatures below freezing determines the low-temperature power capability of a battery. Sub zero transport kinetics are characterized by a sharp rise in internal resistance due to the high activation energy of desolvation. This restriction limits the discharge and charge rates of cells in cold climates.
Electrolyte Viscosity
Viscous drag increases significantly as the temperature drops, slowing down the diffusion of ions through the liquid medium. For sub zero transport kinetics, this slow diffusion leads to polarization at high currents. Choosing solvents with low freezing points improves the mobility of the ions.
Lithium Plating
Insufficient diffusion of ions into the anode structure during charging causes metal to deposit on the graphite surface. Under sub zero transport kinetics, this plating poses a major safety risk due to dendrite formation. Fast charging must be avoided under these cold conditions.
Additive Solution
Specific functional chemicals in the electrolyte form a thin and conductive solid interphase that reduces the transfer resistance. When studying sub zero transport kinetics, these additives lower the energy barrier for lithium-ion desolvation at the surface. This chemical adjustment allows cells to maintain acceptable power output even in winter environments, which expands the operational range of electric vehicles.
