Li_6.4La₃Zr_1.4Ta_0.6O₁₂-Reinforced Hybrid Eutectic Polymer Electrolyte With Balancing Ionic Conductivity and Mechanical Strength for Lithium Metal Batteries

Abstract

The long-standing “solidification penalty” and inherent strength-conductivity trade-off have severely restricted the development of high-energy-density lithium metal batteries (LMBs), as conventional solid-state electrolytes inevitably compromise ionic transport for enhanced safety. Herein, we rationally design a Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO)-reinforced hybrid eutectic polymer electrolyte (HEE@PF) that subverts this long-held paradigm. The HEE@PF delivers a room-temperature ionic conductivity of 0.484 mS cm⁻¹, exceeding that of its liquid eutectic precursor (0.336 mS cm⁻¹), while simultaneously doubling puncture strength to 5.5 N, enabled by multiscale synergistic reinforcement mechanisms. LLZTO functions not merely as an inert filler but as a multifunctional active component: it promotes extensive dissociation of LiTFSI, facilitates the formation of percolating ion-conducting pathways, and selectively modulates the decomposition of TFSI⁻ anions to engender a robust, Li₂SO₄–enriched solid electrolyte interphase (SEI). Consequently, Li| |Li symmetric cells demonstrate long-term cycling stability (> 600 h at 0.1 mA cm⁻²), and Li| |LiFePO₄ (LFP) full cells retain 80.1% of their initial capacity after 400 cycles at 1 C. Moreover, the system exhibits outstanding rate capability and high-temperature resilience, delivering a stable specific capacity of 99.4 mAh g⁻¹ after 800 cycles at 1 C under 60°C. This work establishes a generalizable design strategy by transforming passive ceramic fillers into multifunctional active components, accelerating the practicalization of safe high-performance LMBs.

Keywords

composite solid-state electrolytes / hybrid eutectic polymer electrolyte / lithium lanthanum zirconate (LLZTO) / lithium metal batteries / solid electrolyte interphase (SEI)

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2026 The Author(s). Battery Energy published by Xijing University and John Wiley & Sons Australia, Ltd.