Hierarchically Engineered Transition Metal Electrode for Direct Lithium Extraction From Brine

ABSTRACT The global transition to net‐zero has positioned lithium (Li) as a critical mineral for electrification and energy storage. While the electrochemical intercalation/deintercalation (EID) approach from unconventional brine sources offers a promising Li extraction pathway, it is typically challenged by electrode materials that rely on critical minerals such as Mn, Co, and Li, which present stability issues and require prior electrode delithiation. This study investigates the potential of tungsten trioxide (WO ₃ ) nanoparticles synthesized via flame spray pyrolysis (FSP) and further surface modified with reduced graphene oxide (rGO) derived carbon as a novel material for lithium extraction from synthetic brine (Li~1057 ppm), exhibiting intercalation capacity of 3 mmol Li g ⁻¹ h ⁻¹ with recovery efficiency of 43% in simulated Hombre Muerto brine. X‐ray photoelectron spectroscopy (XPS) analysis confirmed W ⁶⁺ reduction and Li 1s peaks upon intercalation into WO ₃ . Through a suite of in‐situ and ex‐situ X‐ray absorption spectroscopy (XAS) measurements, we demonstrate reduction of W ⁶ ⁺ during Li intercalation, followed by reoxidation upon deintercalation. This work establishes carbon modified WO ₃ as an efficient material for lithium extraction from aqueous brines while elucidating the underlying intercalation/deintercalation mechanism.