Electric-field-induced vertical orientation of LATP nanoparticles in composite polymer electrolytes for enhanced solid lithium metal battery performance

Solid-state composite polymer electrolytes represent a promising strategy for lithium metal batteries; however, challenges regarding ionic conductivity persist. While the construction of continuous ion transport pathways has been demonstrated to effectively enhance conductivity, the rational design and fabrication of such architectures remain challenges. Herein, we report a solid-state electrolyte featuring vertically oriented inorganic fillers fabricated via electric-field-induced orientation of photopolymerizable monomer solutions, with Li₁.₃Al₀.₃Ti₁.₇(PO₄)₃ (LATP) employed as a representative example. This vertical orientation establishes continuous LATP–polymer interfaces serving as rapid Li⁺ transport pathways, enhancing ionic conductivity and mechanical modulus. XPS depth profiling reveals that oriented LATP strengthens TFSI⁻ interactions, forming a bilayer SEI with flexible organic exterior and rigid inorganic interior. The oriented electrolyte delivers 145.3 mAh g⁻¹ after 220 cycles (60 °C, 0.1C), surpassing 132.1 mAh g⁻¹ for the non-oriented counterpart.