Novel fast ionic conductor ceramic composite separator for high-performance safe Li-ion power batteries

Abstract

The ceramic composite separators coated with silica or alumina particles have been used in power batteries due to their better electrolyte wettability and better thermal stability compared with bare polymer separators. However, these oxide ceramics are Li+ ion insulators, which increase internal resistance and hinder the improvement of rate capability of batteries. Herein, we report a strategy to further improving the performance of lithium-ion batteries (LIBs) by using fast ionic conductor ceramic composite separator as an alternative to traditional ceramic coated separators. Lithium lanthanum titanate (LLTO), a fast ionic conductor with excellent room temperature bulk conductivity, are coated on the common polyethylene (PE) separators. Our results demonstrate that such a novel LLTO-coated separator possess excellent electrolyte wettability and thermal stability; and the assembled NCM523/graphite lithium-ion pouch cells with LLTO-coated separator show better rate capability and cyclic performance with 88.7% capacity retention after 1000 cycles at room temperature compared with the pouch cells with Al2O3-coated separators. The fast ionic conductor ceramic composite separators will be a potential competitor to the next-generation novel separators for high-performance Li-ion power batteries.

Keywords

• Li-ion batteries
• Ceramic composite separator
• LLTO
• Fast ionic conductor
• Pouch cells