Meaning
Ionic migration occurs through the dense crystal lattice of a solid material without the aid of a liquid medium. This mechanism describes how ions hop between vacant sites in a solid electrolyte or electrode particle. Solid-state mass transport is typically much slower than liquid-phase diffusion and acts as a major constraint on the performance of next-generation batteries.
Activation Energy
Moving an ion from one site to another requires overcoming a physical barrier defined by the surrounding atoms. High temperature provides the thermal energy needed to accelerate solid-state mass transport and lower the internal resistance of the cell. Low temperature leads to a dramatic slowdown in these kinetics, often making solid batteries unusable in cold climates.
Engineers seek materials with lower energy barriers to improve the power output of these devices.
Lattice Pathway
The arrangement of atoms determines the width and shape of the tunnels available for ion travel. Efficiency in solid-state mass transport depends on the crystal symmetry and the presence of defects that can either facilitate or block movement.
Interface Resistance
Contact between different solid materials can create a zone where ion flow is severely restricted. Improvements in solid-state mass transport involve engineering these boundaries to allow a transition from the electrolyte into the electrode.
