Constructing vertically aligned Li+ transport pathways in a flexible solid polymer composite electrolyte by a soft template approach

Abstract

Solid-state electrolytes provide excellent electrochemical stability, mechanical strength, and safety as compared to conventional liquid electrolytes for lithium-ion batteries. Recent advancements in polymer electrolytes mixed with nanofillers have enhanced ionic conductivity and stability owing to the interaction between nanoscale fillers and polymer matrix/lithium salt. However, the dispersion of isolated nanofillers affects the continuous lithium-ion transport pathways, thereby preventing the composite electrolyte from further improving its conductivity and stability. In this study, by using a sol–gel-template method, we prepared Li_0.5La_0.5TiO₃ (LLTO) nano-arrays with vertically aligned structures as nanofillers in composite polymer electrolytes. The elongated, direct Li⁺ transport pathways formed by the LLTO nano-arrays allow for a 30 wt% filler ratio in the composite electrolyte, achieving a conductivity of 5.6 × 10⁻⁵ S cm⁻¹ at 25 °C and 1.05 × 10⁻³ S cm⁻¹ at 70 °C. This significant conductivity enhancement in the composite electrolyte also contributes to improved electrochemical and thermal stability. The vertical LLTO nano-bundle arrays (VLNA) structure represents a promising approach for high-performance composite polymer electrolytes for next-generation lithium batteries. Furthermore, this sol–gel-template method could be adapted to other kinds of inorganic ceramic electrolytes, expanding its applicability across different electrolyte systems.