Meaning
Dynamic movement of ions through the electrode bulk and across solid state interfaces represents this electrochemical property. Factors influencing lithium transport kinetics determine the maximum power density a battery cell can deliver. It accounts for both the diffusion through the crystal lattice and the migration through the solid electrolyte interphase.
Ionic Diffusion
Path length and crystal structure determine how quickly a cell can be charged or discharged. Fast lithium transport kinetics are associated with materials that offer clear pathways for ion migration (round brackets) such as layered oxides or spinels. Shortening the diffusion distance through smaller particle sizes also enhances the overall rate capability.
Researchers often use electrochemical impedance spectroscopy to isolate these values from other resistive components.
Charge Capability
Rapid movement of charge carriers prevents the buildup of internal resistance during high current pulses. When lithium transport kinetics fail to match the demand of the external circuit, the voltage drops prematurely. This limitation prevents the use of certain high capacity materials in electric vehicle applications.
Phase Transition
Structural changes within the cathode during cycling can block the movement of ions. A degradation in lithium transport kinetics often signals the onset of lattice strain or the formation of resistive surface layers. Maintaining high mobility throughout the life of the cell ensures consistent performance across various temperatures.
