Two Laser and Secondary Ion Mass Spectrometry of Lithium Ion Batteries and Small Molecule Drugs

Mass Spectrometry (MS) imaging is widely used to create chemical maps and/or depth profiles of a wide range of biological and synthetic samples, including electronic devices. Picosecond laser desorption photoionization mass spectrometry (ps-LDPI-MS) offers the potential for improved and complementary analysis of molecular species compared to established MS imaging methods like time-of-flight secondary ion mass spectrometry (ToF-SIMS). Operation of the home-built ps-LDPI-MS instrument is described along with further developments including introduction of a pulsed valve and a photoelectron-based strategy to improve postionization of laser desorbed neutrals. The ps-LDPI-MS instrument is used to analyze four imipramine class tricyclic antidepressants. Molecular and fragment ion signals for all four compounds are compared to electron impact mass spectral libraries, but ps-LDPI-MS displayed much higher molecular ion signal. A pivot is then made to the use of a commercial ToF-SIMS instrument for the analysis of candidate solid state electrolytes that are under development for improved lithium-ion batteries. ToF-SIMS visualized metallic lithium distribution with respect to ceramic fibers and composite polymer electrolyte. The 3D imaging and depth profiling capabilities are also applied to several other types of candidate solid electrolytes to explore the structure and chemistry of their solid electrode-electrolyte interface. Finally, ToF-SIMS is compared to a new photoelectron-based ionization strategy in ps-LDPI-MS for the analysis of the solid electrode-electrolyte interface modified by a novel lithium-ion salt.