Meaning
Electrical measurements against internal ion mobility determine the voltage losses occurring in an electrochemical cell. The electrolyte ohmic resistance measures the resistance to the flow of ions through the liquid filled separator and the porous electrode matrix. This property varies directly with electrolyte temperature and concentration.
It dominates the immediate voltage drop when a load is applied, which directly affects the power density of the device. Consequently, electrolyte selection focuses on optimizing chemical compositions.
Conductivity Determinant
The physical properties of the solvent and the salt concentration determine the ion conduction rate. In the electrolyte ohmic resistance model, higher salt concentrations increase the number of charge carriers up to a maximum conductivity point. Beyond this point, ion-pair formation reduces mobility.
Thermal Impact
Low temperatures increase electrolyte viscosity and reduce ion mobility. This shift increases the electrolyte ohmic resistance by an order of magnitude, causing the operating voltage of the cell to drop below the minimum threshold. Thus, low-temperature operations suffer from severe capacity losses.
Voltage Drop
Immediate voltage changes following the initiation of a current pulse are caused by resistance within the liquid path. Knowing the electrolyte ohmic resistance is essential for calculating the thermal dissipation during high-rate discharges. Designers use this information to calculate thermal protection limits.
