Meaning
Solid phase separation occurs when dissolved lithium components reach their solubility limit and settle out of the liquid solvent. Occurrences of electrolyte salt precipitation usually coincide with extremely low temperatures or high local concentrations resulting from solvent evaporation. The resulting solids block pore spaces and increase internal impedance by removing charge carriers from the active solution.
Saturation State
Cooling a saturated liquid lowers the energy available to keep solid molecules in a dissolved arrangement. During electrolyte salt precipitation the viscosity of the fluid rises rapidly as it approaches the crystallization threshold. This state inhibits the movement of ions between the positive and negative poles during high current pulses.
System Block
Obstruction of the microscopic gaps in the separator layer creates an uneven current distribution. Because electrolyte salt precipitation occurs most frequently in the smallest pores, it forces the current to crowd into larger open channels. This crowding speeds up degradation in localized spots and lowers the safety margins of the pack.
Temperature Effect
Exposure to sub-zero environments is the most frequent trigger for this chemical shift. Monitoring electrolyte salt precipitation involves testing the recovery of the cell once thermal conditions return to the specified operating room temperature.
