Ion selective rapid transport enabled by functionalized CeO2/LiX zeolite modified separator in high performance lithium sulfur batteries

With regard to the issues in the application of lithium sulfur batteries (LSBs), for instance, the low-rate performance due to the difficulty in Li⁺/S2-n diffusion, and the poor cycling stability caused by lithium dendrites and polysulfide shuttle. This work reports a unique strategy for protecting lithium anode, that is, using the “size sieving” and “Donnan effect” of CeO₂/LiX modified separator to simultaneously regulate the transfer behavior of Li⁺/S2-n based on the differences in size and charge. The CeO₂, which is carefully constructed with oxygen defects, together with the negatively charged properties of zeolite framework, exhibits a synergistic relationship in controlling the flux and diffusion rate of Li⁺ and suppressing the polysulfide shuttling, which is confirmed by the experimental and theoretical investigations. As a result, the symmetric cell assembled with CeO₂/LiX modified separator achieves stable cycling for 5000 h at 5 mA cm⁻² and 5 mA h cm⁻², and a deep Li stripping/plating for more than 2000 h at 10 mA h cm⁻². The corresponding full battery shows a competitive areal capacity of 4.7 mA h cm⁻² under a high sulfur loading of 4.0 mg cm⁻². This strategy offers a low-cost solution to achieve the practical application of LSBs.