Halloysite-derived mesoporous silica with high ionic conductivity improves Li--S battery performance.

The slow Li⁺ transport rate in the thick sulfur cathode of the Li--S battery affects its capacity and cycling performance. Herein, Fe-doped highly ordered mesoporous silica material (Fe--HSBA-15) as a sulfur carrier of the Li--S battery shows high ion conductivity (1.10 mS cm^-1) and Li⁺ transference number (0.77). The Fe--HSBA-15/S cell has an initial capacity of up to 1216.7 mA h g^-1 at 0.2C and good stability. Impressively, at a high sulfur load of 4.34 mg cm^-2, the Fe--HSBA-15/S cell still maintains an area specific capacity of 4.47 mA h cm^-2 after 100 cycles. This is because Fe--HSBA-15 improves the Li⁺ diffusion behavior through the ordered mesoporous structure. Theoretical calculations also confirmed that the doping of iron enhances the adsorption of polysulfides, reduces the band gap and makes the catalytic activity stronger. [ABSTRACT FROM AUTHOR]