The Li6.4La3Zr1.4Ta0.6O12-coated polyethylene terephthalate / Lyocell composite separator for lithium-ion batteries

Abstract

The commonly used polyolefin separators face challenges such as poor electrolyte wettability, severe thermal shrinkage, and significant lithium dendrite growth, which significantly limit the further development and energy density enhancement of lithium-ion batteries. Therefore, the design and fabrication of advanced separator materials with excellent wettability, high mechanical strength, and inhibition of dendrite growth are essential for the next generation of lithium-ion batteries. In this study, a novel separator is developed using Li6.4La3Zr1.4Ta0.6O12 (LLZTO), polyethylene terephthalate (PET), and Lyocell, fabricated through a wet papermaking process combined with coating technology. The LPC separator exhibits high mechanical strength (56.98 MPa), small pore size (226 nm), and thin thickness (19.63 μm). The Lyocell layer demonstrates strong affinity for the electrolyte, the PET layer enhances the separator's tensile strength, and the LLZTO layer effectively prevents internal short circuits and deterioration in battery performance. The LPC15 separator battery achieves an initial specific capacity of 184.2 mAh g-1, with a capacity retention of 96.3 % after 100 cycles at 30°C and 1 C. Under −10°C and 0.2 C conditions, the initial specific capacity reaches 129.3 mAh g^-1, with an impressive capacity retention of 99.6 % after 100 cycles, thanks to the LLZTO layer.