High dielectric single-ion conducting interphase enables fast-charging lithium metal batteries

The poor stability and slow lithium ion (Li + ) transfer kinetics of solid electrolyte interphase (SEI) pose significant challenges to lithium (Li) metal batteries. Although various SEI-related strategies have been developed, the Li + transport properties and uniform Li deposition still require substantial improvement for fast-charging applications. Herein, we introduce a dielectric , single-ion-conductive artificial SEI (DS-SEI) composed of lithiated Nafion and BaTiO 3 (BTO) nanoceramics to address these issues. The lithiated Nafion stabilizes the Li anode with its elastic F-rich components and facilitates fast, single Li + conduction through its anion-anchored structure. The high-dielectric BTO dynamically homogenizes the electric field (E-field) to promote uniform Li deposition, synergistically enhancing intrinsic single Li + conductivity and Li + desolvation/diffusion kinetics, thereby enabling fast charging of the Li anode. Consequently, the DS-SEI protected Li anode can cycle over 6800 h in a Li||Li cell at 10 mA cm −2 /5 mAh cm −2 , over 400 cycles in a 2.75 mAh cm −2 Li||LiFePO 4 cell at 1C, with 83.0 % capacity retention at 6C (16.5 mA cm −2 ), and maintain stable cycling in a 5.62 mAh cm −2 Li||Li 6 PS 5 Cl|| LiNi 0.8 Co 0.1 Mn 0.1 O 2 all solid-state cell. Our findings provide insights into the interfacial regulation of Li anode, paving the way for fast-charging Li metal batteries.