context: Fig. 2a shows the 7Li in situ NMR spectra continuously acquired during a 0.5 mA cm−2 constant current experiment. The resonance from Li metal depends on the orientation of the Li metal anode strip with respect to the static magnetic field, B0, due to Li metal's temperature independent paramagnetism (TIP). Aligning the cell perpendicular to the B0 field results in a 7Li resonance at around 245 ppm for the pristine Li metal (Fig. 2a) and all in situ cells presented in this work were aligned in this fashion. When depositing Li in both LP30 and LP30 + FEC, a new peak around 260 ppm emerges that continues to grow as a current of 0.5 mA cm−2 is passed (Fig. 2a). This new resonance is indicative of mossy structures growing near to the Li metal surface. Whisker-like morphologies are observed in the SEM micrographs as the major morphology after plating for 3.5 mA h cm−2 in LP30 electrolyte, whereas dense, thick buds (diameter of surface features ∼5–10 μm) are observed for LP30 + FEC (Fig. 2b).
answer: LP30