Facile preparation of ultrafine Ti4O7 nanoparticle-embedded porous carbon for high areal capacity lithium–sulfur batteries

Abstract

Lithium–sulfur batteries have been investigated as promising energy storage systems due to their high energy density of 2600 W h kg⁻¹. Although various materials as sulfur hosts can improve the performance of lithium–sulfur batteries, expensive raw materials, complex synthesis and lower sulfur loading impede their practical application. Herein, ultrafine Ti₄O₇ nanoparticle-embedded porous carbon (PC@Ti₄O₇) as an efficient sulfur host was facilely prepared using commercial TiO₂ nanoparticles and phenolic resin. In this strategy, the highly conductive ultrafine Ti₄O₇ nanoparticles with abundant active adsorption sites can efficiently trap polysulfides and accelerate their conversion. In addition, the size of the Ti₄O₇ nanoparticles, depending on the commercial TiO₂ nanoparticles, could be easily controlled. Moreover, the sufficient interspaces around the Ti₄O₇ nanoparticles are beneficial for maximizing the confinement of polysulfides. The hybrid cathode exhibits excellent cycling stability at a high rate of 4C over 1000 cycles. Particularly, the electrode with a sulfur loading of up to 15.6 mg cm⁻² retains an ultrahigh areal capacity of 8.6 mA h cm⁻² at 0.3C over 100 cycles. The low-cost and facile preparation of the PC@Ti₄O₇ composite provides new insight for the practical application of lithium–sulfur batteries.