Meaning
Spectroscopic analysis evaluates the local chemical environment and atomic mobility in rigid or semi-rigid materials. Utilizing solid state NMR is essential for characterizing ion transport mechanisms in crystalline and polymer battery electrolytes. Unlike liquid-state alternatives, this method must resolve the strong anisotropic interactions present in the solid state.
This capability makes it indispensable for mapping the pathways of lithium or sodium ions as they move through the solid lattices of solid-state batteries.
Rotational Resolution
High-speed rotation of the sample at a specific angle relative to the magnetic field is required to narrow the spectral lines. In solid state NMR, this magic angle spinning averages out the dipolar couplings and chemical shift anisotropy. This averaging produces sharp peaks that allow the identification of distinct atomic environments.
Ion Mobility
Variable temperature experiments are conducted to measure the diffusion coefficients of active ions. Performing solid state NMR over a range of temperatures reveals the energy barriers associated with ion hopping. These data help researchers design solid electrolytes with higher ionic conductivity.
Industrial Application
Battery manufacturers use this technique to study the degradation of cathode materials during prolonged cycling. It provides a non-destructive way to quantify the amount of electrochemically inactive lithium that has accumulated. This capability is valuable for evaluating the life expectancy of experimental cell chemistries.
