CoTe nanoparticle functionalized separator for simultaneously inhibiting the shuttle effect and lithium dendrite in Li–S batteries

Abstract

The shuttling of dissolved polysulfides and lithium dendrite growth causes poor cycling stability, seriously hindering the practical use of Li–S battery. Herein, a multifunctional separator is designed by introducing CoTe nanoparticles on conventional Celgard separator via vacuum filtration to solve the above-mentioned problems for Li–S battery. The CoTe nanoparticles on the separator are able to effectively catalyze polysulfide conversion and inhibit the shuttle effect. More importantly, the CoTe nanoparticle modified separator suppresses the growth of Li dendrite in anode by regulating the deposition morphology of Li. After the introduction of the CoTe nanoparticle modified separator, the assembled Li‖Li symmetrical battery achieves stable lithium deposition/stripping for up to 750 h at a current density of 1 mA cm⁻² and a discharge capacity of 1 mAh cm⁻². The Li–S battery using a CoTe nanoparticle modified separator achieves a high capacity of 564.5 mAh g⁻¹ at 3 C and the decay rate per cycle is only 0.093% after 500 cycles at 1 C. Even under high sulfur loading of 4.59 mg cm⁻² and low E/S ratio of 8 μL mg⁻¹, the sulfur cathode with CoTe nanoparticle modified separator demonstrates a remarkable capacity of 667.9 mAh g⁻¹ at 0.5 C.