Synergistic effect of the PMIA nanofiber membrane with a dual-oriented network structure and Li0.5Bi0.5TiO3 nanofibers for high-performance lithium metal batteries

Abstract

Solid-state lithium metal batteries are favored for their superior energy density and safety compared to liquid batteries. However, the low ionic conductivity and weak mechanical properties of the polyethylene oxide (PEO) solid electrolyte hinders their development. In this study, poly-m-phenyleneisophthalamide (PMIA) nanofibers with a dual-oriented network and the piezoelectric ceramics Li_0.5Bi_0.5TiO₃ (LBTO) nanofibers were integrated in a composite electrolyte. PMIA incorporation could enhance the mechanical strength, reduce the dendrite piercing risk, and homogenize lithium ions (Li⁺), while LBTO with its strong TFSI⁻ adsorption could accelerate LiTFSI dissociation, promote Li⁺ transport, and ensure uniform dispersion. The LBTO/PMIA/PEO/LiTFSI electrolyte boasted high ionic conductivity (4.17 × 10⁻⁴ S cm⁻¹ at 50 °C), strength (20.45 MPa), and Li⁺ migration (0.45 at 50 °C). In addition, the Li–Li symmetric cell could be run stably for more than 3000 h without short circuiting at 0.1 mA h cm⁻². The assembled LiFePO₄‖Li full cells display excellent long cycling stability at 50 °C (>500 cycles). More strikingly, the LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)‖Li full cell could also can be run for 200 cycles. This multi-functional electrolyte offers a promising approach to realizing high-performance solid-state lithium batteries.