A Sphere-Sheet Hetero-Interlayer With Mechanoadaptivity and Li+ Selectivity for High Performance Anode Free Lithium Sulfur Batteries.

Abstract

Anode free lithium sulfur batteries (AFLSBs) can fully exploit the ultra-high energy density of Li-S systems. However, issues such as irreversible lithium loss caused by uneven solid electrolyte interphase (SEI) on anode during the charging/discharging process, along with severe volume changes leading to structural instability, are key factors limiting their lifespan far below practical application. Herein, a sphere-sheet hetero-interlayer (2DLP-PASF) is designed, which adapts to volume changes and exhibits Li+ selectivity. The interlayer is fabricated by electrophoretic deposition of -SO3Li rich elastic ionomer emulsion (PASF) particles and laponite nanosheets (2DLP) onto a copper current collector. The elastic PASF particles support 2DLP to form a dispersed stress-buffering structure, which can accommodate volume changes during the charging/discharging process and suppress dendrite growth. Furthermore, rich -SO3Li in densely packed PASF shells between 2DLP repel anions electrostatically through the Donnan effect, which facilitates efficient Li+ transport and flux homogenization, thereby inhibiting the polysulfide shuttle. Additionally, -C≡N and -CF3 in PASF cores transform into a stable, Li3N/LiF-rich secondary SEI on anode, which in turn synergizes with the tough 2DLP-PASF to further stabilize lithium deposition. As a result, the AFLSB assembled with 2DLP-PASF modified copper current collector and Li2S cathode demonstrated significantly improved comprehensive electrochemical performance.