A polyaniline-coated Ni–Co Prussian blue analogue nanocube-modified separator for high-performance lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries have gained significant attention as promising candidates for next-generation energy storage systems due to their high theoretical energy density. However, their commercialization has been limited due to serious polysulfide dissolution. Herein, we synthesized polyaniline-coated Ni–Co Prussian blue nanocubes (NCP@PANi) for Li–S battery separator modification using a simple coprecipitation and in situ oxidation polymerization method. The synergistic catalytic effect of Ni and Co bimetallics enhanced the cathodic reaction kinetics. In addition, the coating of PANi on the NCP surface further improved the electrical conductivity and adsorption of polysulfides. The sulfur/ketjen black cathode (S/KB) using the modified separator exhibited an initial discharge specific capacity of 1443.1 mA h g⁻¹ at 0.1C. Even at a high sulfur loading of 3.1 mg cm⁻², it exhibited an initial capacity of 713.9 mA h g⁻¹ at 0.5C and maintained 431.3 mA h g⁻¹ after 300 cycles. Overall, the NCP@PANi modified separator effectively inhibited the polysulfide shuttling and thus improved the electrochemical performance. This study provides valuable insights into separator modification for Li–S batteries.