A new type of LATP doped PVDF-HFP based electrolyte membrane with flame retardancy and long cycle stability for solid state batteries

Abstract

Lithium ion batteries are a widely used high-density energy storage device due to their low self-discharge rate and lack of memory effect. However, their use in liquid electrolyte systems poses a significant safety risk due to issues such as lithium dendrite growth and toxic electrolytes that are also prone to leakage. Therefore, the development of gel polymer electrolytes (GPE) with high ionic conductivity and elevated lithium ion migration numbers is crucial to addressing these concerns. This work focuses on the preparation of flexible microporous composite gel polymer electrolytes (L-GPE) based on Polyvinylidene fluoride-Hexafluoropropylene (PVDF-HFP) and Li_1.3Al_0.3Ti_1.7P₃O₁₂ (LATP) as a filler and on testing its performance as an electrolyte in applications of lithium ion battery. The L-GPE demonstrated an ionic conductivity of 8.13 × 10⁻⁴ S·cm⁻¹ at 40 °C, with a lithium ion mobility number of 0.58, indicating high ionic mobility. Notably, in all-solid-state lithium ion battery applications, the L-GPE demonstrated excellent long-cycle stability, with a capacity retention of 90.3 % after 1000 cycles at 0.5C. These results demonstrate that the interaction force between LATP and anions enhances lithium ion mobility in composite gel polymer electrolytes, which is favorable for the regulation of lithium ion deposition and the control of lithium dendrite growth. Besides, the performance of this L-GPE membrane is significantly improved due to its suitable porosity, gratifying mechanical properties, and excellent flame retardancy. In summary, this strategy provides a valuable contribution to the development of safe and long-lasting energy storage systems by presenting a novel L-GPE membrane with enhanced mechanical, high ionic conductivity, excellent flame retardant property and thermal stability.