Guidelines for correlative imaging and analysis of reactive alkali metal battery materials

Reliable characterization of alkali metals and their solid electrolyte interphases (SEIs) is essential for advancing high-energy batteries but remains difficult due to their extreme reactivity and beam sensitivity. This work redefines the experimental limits for high-resolution imaging of lithium and sodium metals. Contrary to prevailing assumptions, we show that atomic-resolution transmission electron microscopy (TEM) of lithium metal is achievable at room temperature using inert-gas sample transfer, with electron dose rates above 10 3 e⁄Å 2 ⋅s causing no structural damage. SEI phases such as Li 2 CO 3 and Na 2 CO 3 remain highly beam-sensitive and require cryogenic TEM and strict dose control. We further demonstrate that plasma-focused ion beam (plasma-FIB) milling enables artifact-free lithium lamella preparation at ambient conditions, unlike conventional Ga + FIB. Systematic evaluation of environmental, electron, and ion-beam effects also reveals inconsistencies arising from non-standardized cryogenic workflows. This framework provides a reproducible, damage-minimized pathway for imaging reactive metals and interfaces in next-generation batteries.