Lithium–sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.

Nature Communications 7, Article number: 11203 doi:10.1038/ncomms11203

http://www.nature.com/ncomms/2016/160405/ncomms11203/full/ncomms11203.html

锂-硫电池比传统的锂离子电池能量密度高六倍，因此受到广泛关注。不过，有三个主要因素限制着这一技术的发展，包括多硫化锂的分解、硫的体积膨胀以及硫化锂的沉积。Tao等人合成了一系列以非导电金属氧化物纳米粒子修饰的碳片。基于氧化镁、二氧化铈、氧化镧的阴极材料展现出更高的循环性能。吸附实验和理论计算表明，聚硫化物在氧化物上是通过单层的化学吸附作用完成的。此外，更好的表面扩散还使得硫在电极上有更高的沉积效率。（新材料在线）