Multiple boosting Janus membranes synergized with Li-rich PAF-6 and carbon nanoparticles for high performance lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries are considered to be one of the most promising candidates due to their ultra-high theoretical capacity and extremely low cost when the performance of lithium-ion batteries is close to their theoretical limits. However, their application is still limited because of various defects, such as the polysulfide shuttle effect. Herein, the composite solution of phenylated poly(ether ether ketone ketone) (Ph-PEEKK), nanocellulose (NCC) and porous aromatic frameworks (PAFs) infused with LiTFSI was coated on one side of a Celgard separator (PE) to prepare a Janus membranes (PCP@PE) through phase inversion. Extra Li afforded by the uniformly dispersed Li-rich PAF-6 synergized with carbon nanoparticles obtained by the carbonization of NCC afforded the efficient transfer channels of Li⁺, and effectively prevented the dissolution and shuttle of polysulfides. Plenty of sulfonic acid groups were also thus introduced to inhibit the shuttle effect, and showed an excellent capacity retention rate. The initial capacity reached 1204 mA h g⁻¹ under 0.2C, and 85% of the remaining capacity was retained after 100 cycles. In addition, mechanical properties and dimensional thermal stability were much improved compared with those of PE. There was negligible shrinkage with treatment at 180 °C for 0.5 h for the Janus membranes, which resulted from the high thermal stability of Ph-PEEKK. The results illustrated their huge application potential in Li–S batteries.