Multiscale interfacial stabilization via prelithiation separator engineering for Ah-level anode-free lithium batteries.

Anode-free lithium batteries represent a promising avenue for high-energy-density storage, yet their practical application is hindered by lithium inventory loss from parasitic interfacial reactions, cathode degradation, and limited Li reversibility. Herein, we propose a polyolefin separator integrated with a LiS@C sacrificial layer, achieving multiscale interfacial stabilization in Ah-class anode-free pouch cells. This approach simultaneously replenishes the customized Li inventory during the formation cycle and establishes the lithium polysulfide-containing cathode interface with high-voltage tolerance (till 4.5 V). Real-time tracking via in-situ electrochemical impedance spectroscopy and transmission-mode operando X-ray diffraction reveals accelerated Li diffusion kinetics and stabilized phase evolution in LiNiCoMnO cathode interfaced with LiS@C|PE prelithiation separator. Consequently, a 1.22 Ah pouch cell with an Ag-modified Cu foil and LiNiCoMnO cathode is assembled with LiS@C|PE separator and exhibits gravimetric and volumetric energy densities of 450 Wh kg and 1355 Wh L, respectively. This prelithiation protocol demonstrates upscaling potential and generic applicability to secure the interfacial chemistries for anode free/less lithium metal batteries.