The usefulness of solid state Nuclear Magnetic Resonance (NMR) spectroscopy in the analysis of lithium ion batteries is presented. Some background information on lithium batteries is given, in addition to a summary of current research areas. A comprehensive review of the use of NMR and Electron Paramagnetic Resonance (EPR) in lithium batteries research thus far is also presented. The electrodes studied were the standard LiCoO₂ cathode cycled against mesocarbon microbead (MCMB) anodes, as well as Li₂Ag ₂V₄O₁₁ and CFx cathodes cycled against metallic lithium anodes in primary batteries. The focus of half of the work concerns the elucidation of the Solid Electrolyte Interphase (SEI), an irreversibly formed side-product found on the electrode surfaces, composed mainly from the electrolyte components; one study provides a deeper insight into the inorganic components of the SEI, while the other SEI study focuses on the organic components via ¹³C MAS NMR studies of cycled electrodes. The other half is comprised of two additional studies in which atomic and electronic rearrangement are monitored in the electrodes at different stages of the battery cycling process.