Infinite Functional Versatility, Formidable Limits: Evaluating Gallium‐Based Liquid Metals in Rechargeable Batteries

ABSTRACT Gallium‐based liquid metals (Ga‐LMs) have enabled encouraging conceptual advances in next‐generation rechargeable batteries, combining high electrical conductivity, self‐healing behavior, strong metal‐ion affinity, and spontaneous alloying. Demonstrations across Li‐ion, Li metal, Na‐ion, Na metal, Zn‐ion, Mg‐ion, and Li–S systems highlight Ga‐LMs' versatility as binders, conductive networks, interfacial wetting agents, and protective coatings—helping to mitigate volume changes, accelerate kinetics, and suppress dendrite formation. While it remains premature to assess their commercial readiness, a critical evaluation of these conceptual breakthroughs is timely, particularly in comparison to mature functional materials and realistic lab‐scale cell standards. Many reported Ga‐LM components are fabricated under conditions that diverge from scalable battery manufacturing practices (e.g., nonstandard electrode preparation) and tested under relaxed conditions (e.g., low mass loading, flooded cells, low current densities). Key challenges, including nanoparticle agglomeration, gravimetric energy penalties, unwanted reactions with battery components, phase transition‐induced solid–electrolyte interphase (SEI) instability, and long‐term stability under standard cycling protocols, remain unresolved or, more accurately, largely unexplored. Moreover, gallium's limited and geographically concentrated production raises important concerns regarding cost, scalability, and long‐term materials stewardship. In this perspective, we critically assess the core hypotheses driving Ga‐LM integration, benchmark reported performance against established standards and examine how recent in situ and operando characterization strategies, together with emerging end‐of‐life recovery and recycling pathways, inform both the mechanistic understanding and the sustainability of Ga‐LM deployment. By identifying where Ga‐LMs provide genuine advantages, and where more established strategies remain preferable, we offer constructive recommendations to guide future research toward solutions that can transition from inspiring lab‐scale concepts to commercially relevant technologies.