Freestanding TiO@heteroatom-doped hollow multi-channel carbon fibers for lithium-sulfur batteries

Lithium-sulfur batteries are a promising candidate for the future energy storage devices due to its ultrahigh theoretical specific capacity. However, the sluggish redox reactions, large volume changes and shuttle effect of lithium-sulfur materials have limited its large scale applications. In this work, the hollow multichannel structure of freestanding carbon fibers were prepared by coaxial electrospinning and following high temperature treatment, which can provide abundant void to relieve the volume expansion of sulfur cathodes during charge-discharge and facilitates the permeation of electrolyte. Then the titanium oxide was successfully incorporated into carbon fibers to enhance the adsorption capacity for soluble polysulfides (Li2Sn, 4 <= n <= 8). Finally, the boron and phosphorus elements were doped into carbon fibers to improve the electronic conductivity of the cathodes. As result, the three-dimensional TiO@boron-doped hollow multichannel carbon fibers/sulfur cathode with a sulfur loading of 2.26 mg cm-2 deliver a high specific capacity of 1070 mAh g-1 and good cycling performance with capacity decay rate of 0.096% per cycle over 300 cycles at 0.1 A g-1. The strategy of hollow multi-channel structure design, heteroatom-doping and introduction of metal oxides with polar surfaces will provide a new idea for high performance lithium-sulfur batteries. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study successfully addressed the challenges of volume expansion and electrolyte permeation in lithium-sulfur batteries by preparing hollow multichannel carbon fibers. Incorporation of titanium oxide and boron/phosphorus doping effectively improved the adsorption capacity and electronic conductivity of the cathodes, resulting in high specific capacity and excellent cycling performance.