Ultrathin HfO2-modified carbon nanotube films as efficient polysulfide barriers for Li-S batteries

Ultrathin and cross-stacked carbon nanotube (CNT) films modified with hafnium oxide (HfO2) by atomic layer deposition are employed as efficient polysulfide barriers for high performance Li-S batteries. A HfO2/CNT interlayer has an ultrathin, flexible structure with a thickness of 1.5 μm and an areal density of 0.087 mg cm−2, along with excellent wettability to electrolyte. The highly conductive CNT network and the catalytic surface adsorption of polysulfide species by HfO2 significantly suppress the polysulfides shuttling phenomenon. With high sulfur loadings of up to 75 wt%, electrodes incorporating a HfO2/CNT interlayer show noticeable improvements in various electrochemical properties, including long-term cycling stability (721 mA h g−1 after 500 cycles at 1 C), high rate performance (800 mA h g−1 at 5 C), favorable anti-self-discharge capabilities, and suppression of Li anode corrosion. These results suggest a new and efficient polysulfide trapping material and a viable configuration for high-performance Li-S batteries.