Flexible and foldable N-doped carbon modified silica nanotube/aramid interlayer for high-performance lithium-sulfur battery

Lithium-sulfur (Li-S) batteries have received widespread attention as the next-generation energy storage device. The reduction of rate performance and cycle life caused by the shuttle effect is the main obstacle to its commercialization. The modified material of nitrogen-doped carbon modified hollow silica nanotubes (N,CSNTs) is proposed to suppress the shuttle of polysulfides. The modified material was coated on aramid paper interlayer (AP). The aramid fibre interlayer exhibits excellent flexibility and the interleaved carbon nanotubes in the interlayer can effectively compensate for the poor conductivity of the sulfur electrode. Pure silica nanotubes with hollow structures were selected as the anchoring agent. Firstly, the hollow tubular structure can provide more adsorption sites for polysulfides adsorption than silica spheres, which are highly prone to agglomeration. Second, the polar compound silica can effectively promote the redox reaction of polysulfides. In order to improve the adsorption performance of the materials, we further modified the silica surface using a carbon and nitrogen layer. Combining the strong adsorption performance of the N,C layers and the catalytic oxidation effect of polysulfides of silica, the two synergistically obtain flexible multifunctional interlayers. Therefore, Li-S battery with the modified N,C-SNTs@AP interlayer displayed promising cycle and rate performance. The battery with the N,C-SNTs@AP interlayer retain high specific capacity of 1012 mA h/g after 100 cycles at 0.2C with the capacity retention rate of 86 %. The sulfur mass areal loading increased to 4.1 mg cm-2. The battery can still cycle stably for more than 250 cycles at 1C. The above results indicates that the introduction of N,C-SNTs@AP interlayer should be promising strategy for highly stable Li-S battery.