The multicomponent synergistic effect of a hierarchical Li0.485La0.505TiO3 solid-state electrolyte for dendrite-free lithium-metal batteries

Abstract

Development of a composite electrolyte with high ionic conductivity, excellent electrochemical stability and preeminent mechanical strength is beneficial for suppressing Li-dendrite penetration and unstable interfacial reactions in solid-state Li-metal batteries. Herein, a novel composite electrolyte material comprising perovskite Li_0.485La_0.505TiO₃ (LLTO), poly(ethylene oxide) (PEO), and a barium titanate (BTO)-polyimide (PI) composite matrix has been successfully fabricated. Benefiting from the well-defined ion channels, the resulting BTO-PI@LLTO-PEO-FEC-LiTFSI (BP@LPFL) exhibits excellent cycling stability, low interfacial resistance, enhanced mechanical strength, and high ionic conductivity. Particularly, BP@LPFL possesses an excellent ionic conductivity of 3.0 × 10⁻⁴ S cm⁻¹ at room temperature and achieves a wide electrochemical window of 5.2 V (vs. Li⁺/Li). For Li-LiFePO₄ batteries, such an ingenious structure yields a discharge capacity of 124 mA h g⁻¹ at 0.1 C after 200 cycles at room temperature and delivers a discharge capacity of 165 mA h g⁻¹ at 0.1 C after 110 cycles at 60 °C. Additionally, the symmetric Li cell remains stable after 700 h at a current density of 0.5 mA cm⁻². Furthermore, ex situ X-ray photoelectron spectroscopy and ex situ scanning electron microscopy were used to verify the interface evolution. Besides, a flexible full battery is fabricated, which exhibits impressive performance. These properties presented here provide support for BP@LPFL as a feasible candidate electrolyte for solid-state lithium batteries.