Dual-halide solid electrolyte interphase engineering with MXene enables dense (110)-oriented Li deposition for high-performance Li metal anodes

Abstract

For lithium (Li) metal anodes, continuous formation and fractures of the solid electrolyte interphase (SEI) during cycles lead to unstable interfacial evolution, which ultimately triggers dendrite growth. To regulate the Li anode interface, in this work, we prepared the MXene nanosheets with -F/-Cl functionalization (M-FCl) to facilitate the in-situ generation of a LiF/LiCl-rich SEI. The synergistic effects of LiF (with high mechanical strength and a wide bandgap) and LiCl (with a low Li+ diffusion barrier) contribute to a dense, uniform SEI. This structure promotes a homogeneous Li+ flux, guiding Li deposition along the (110) orientation beneath the SEI. The induced Li (110) plane further enhances the surface migration of Li atoms, preventing tip aggregation and promoting planar, dendrite-free Li growth. Consequently, the Li symmetric cell with M-FCl delivers stable operation for over 12,000 h without significant voltage polarization (8.3 mV). Furthermore, practical full cells paired with LiFePO4 cathodes exhibit markedly enhanced cycling stability and prolonged lifespan. This strategy, which involves engineering a LiF/LiCl-rich SEI to improve Li+ diffusion kinetics and guide Li deposition, paves the way for future applications in Li metal batteries (LMBs).