Strategic approaches to observing 39K NMR signals from potassium–graphite intercalation compounds

Abstract Solid-state nuclear magnetic resonance is an invaluable tool for potassium–graphite intercalation compounds, promising anode materials of K-ion batteries, but it has not yet been applied because of several issues. We attempted 39K NMR measurements of potassium–graphite intercalation compounds sealed in glass using an 18.8 T NMR spectrometer with a nuclear magnetic resonance probe adjusted to the samples. The first observed 39K NMR signal of potassium–graphite intercalation compounds showed the possibility of evaluating intralayer density, which cannot be ascertained from Raman measurements.