High Ionic Conductivity Conjugated Artificial Solid Electrolyte Interphase Enabling Stable Lithium Metal Batteries

Abstract

Lithium metal batteries (LMBs) are promising for next-generation high-energy-density batteries but suffer from severe interface instability on reactive Li metal, resulting in poor cycling performance and resource inefficiency. In this study, we present a durable artificial solid electrolyte interphase (SEI) layer (composed of organic conjugated polyacrylonitrile (CPAN) and uniformly dispersed inorganic ZnO nanoparticles, denoted as CPAN@ZnO) by an eco-friendly approach, with reduced energy consumption and minimized thermal degradation byproducts. The unique conjugated structure of CPAN exhibits homogeneous surface electrostatic potential (ESP) distribution. When coupled with lithiophilic ZnO, this interaction induces more homogeneous Li deposition and inhibits dendrite growth. Additionally, its great binding energy with Li and rapid ion migration pathways effectively promote the de-solvation of Li+ and enhance interfacial transport kinetics. Therefore, the CPAN@ZnO SEI exhibits high ionic conductivity, suppressing “dead Li” and dendrite, thus enhancing interface stability and extending Li anode lifespan. As a result, the CPAN@ZnO@Li symmetrical cell achieves an ultralong cycling life over 5400h with a low overpotential, showcasing exceptional cycling stability. Furthermore, the Li-limited full cell NCM811||CPAN@ZnO@Cu (N/P=0.6) delivers stable cycling over 100 cycles with a capacity retention of 88.8%. This work provides valuable insights into high ionic conductivity SEI design for stable cycling of Li-limited LMBs, reducing reliance on anode mining and mitigating environmental impacts from electrode material production, thereby contributing to resource sustainability.