Corrosion of Alkali‐Metal Anodes: Mechanisms, Mitigation, and Quantification

Alkali‐metal anodes combine high theoretical specific capacities with highly negative redox potentials, but the same thermodynamic attributes make them intrinsically reactive toward practical electrolytes. The resulting corrosion continuously consumes active metal and electrolyte during both cycling and storage, yet it is often discussed only indirectly through solid electrolyte interphase (SEI) instability, dendrite formation, or inactive‐metal generation. This review develops a corrosion‐centered framework for Li, Na, and K metal anodes, using Li as the primary evidence base. For mechanistic clarity, operationally distinguish chemical corrosion, arising from spontaneous metal‐electrolyte reactions at the metal surface, from galvanic corrosion, in which active‐metal oxidation is electronically coupled to cathodic electrolyte reduction at a spatially distinct conductive region. Electrolyte reactivity, SEI persistence and permeability, effective metal/electrolyte contact area, current collector exposure, and electrode geometry are identified as key factors governing both corrosion pathways. Mitigation strategies are then organized by their primary interfacial targets. Particular emphasis is placed on what commonly used characterization methods actually measure and on how corrosion rates can be quantified without conflating distinct loss pathways. Finally, standardized testing principles and cross‐chemistry descriptors are outlined to relate corrosion to realistic cycling and calendar life, especially in the comparatively underexplored Na‐ and K‐metal systems.