Enhancing the kinetics of lithium–sulfur batteries under solid-state conversion by using tellurium as a eutectic accelerator

Abstract

Using a solid-state conversion in a liquid electrolyte, lithium–sulfur batteries maintain an advantage of having no polysulfide dissolution; however, they suffer from intrinsically sluggish reaction kinetics. Herein, tellurium is employed as a eutectic accelerator to enhance the reactivity of lithium–sulfur batteries under solid-state conversion. An SEI (solid electrolyte interface) is formed in situ on a CMK-3/S₈ cathode, which enables reactants to undergo solid-state conversion in an ether electrolyte. Electrochemical studies reveal that Te doping can accelerate the diffusion of lithium ions and reduce the reaction resistance, which are beneficial for the reaction kinetics. X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy analyses indicate that Te doping produces an SEI film with high lithium ion conductivity and low impedance. The CMK-3/S-Te-1 cathode, with 1 wt% Te doping, delivers a high reversible specific capacity of 1150.2 mA h g⁻¹ at 0.1C and 726.9 mA h g⁻¹ at 0.2C over 200 cycles. This work furnishes a strategy of using Te as a eutectic accelerator to enhance reactivity for lithium–sulfur batteries under a solid-state conversion and presents a promising avenue for application in lithium–sulfur batteries.