Single-Ion\nConducting Polymeric Protective Interlayer\nfor Stable Solid Lithium-Metal Batteries

Abstract

With\nmany reported attempts on fabricating single-ion conducting\npolymer electrolytes, they still suffer from low ionic conductivity,\nnarrow voltage window, and high cost. Herein, we report an unprecedented\napproach on improving the cationic transport number (<i>t</i>_Li⁺) of the polymer electrolyte, <i>i.e.</i>, single-ion conducting polymeric protective interlayer (SIPPI),\nwhich is designed between the conventional polymer electrolyte (PVEC)\nand Li-metal electrode. Satisfied ionic conductivity (1 mS cm^–1, 30 °C), high <i>t</i>_Li⁺ (0.79), and wide-area voltage stability are realized\nby coupling the SIPPI with the PVEC electrolyte. Benefiting from this\nunique design, the Li symmetrical cell with the SIPPI shows stable\ncycling over 6000 h at 3 mA cm^–2, and the full cell\nwith the SIPPI exhibits stable cycling performance with a capacity\nretention of 86% over 1000 cycles at 1 C and 25 °C. This incorporated\nSIPPI on the Li anode presents an alternative strategy for enabling\nhigh-energy density, long cycling lifetime, and safe and cost-effective\nsolid-state batteries.