Cobalt-Doping of Molybdenum Disulfide for Enhanced Catalytic Polysulfide Conversion in Lithium–Sulfur Batteries

Abstract

Metal sulfides, such as MoS2, are widely investigated in lithium–sulfur (Li–S) batteries to suppress the shuttling of lithium polysulfides (LiPSs) due to their chemical adsorption ability and catalytic activity. However, their relatively low conductivity and activity limit the LiPS conversion kinetics. Herein, the Co-doped MoS2 is proposed to accelerate the catalytic conversion of LiPS as the Co doping can promote the transition from semiconducting 2H phase to metallic 1T phase and introduce the sulfur vacancies in MoS2. A one-step hydrothermal process is used to prepare such a Co-doped MoS2 with more 1T phase and rich sulfur vacancies, which enhances the electron transfer and catalytic activity, thus effectively improving the LiPS adsorption and conversion kinetics. The cathode using the three-dimensional graphene monolith loaded with Co-doped MoS2 catalyst as the sulfur host shows a high rate capability and long cycling stability. A high capacity of 941 mAh g–1 at 2 C and a low capacity fading of 0.029% per cycle at 1 C over 1000 cycles are achieved, suggesting the effectively suppressed LiPS shuttling and improved sulfur utilization. Good cyclic stability is also maintained under a high sulfur loading indicating the doping is an effective way to optimize the metal sulfide catalysts in Li–S batteries.

Enhanced Polysulfide Conversion with Highly Conductive and Electrocatalytic Iodine‐Doped Bismuth Selenide Nanosheets in Lithium–Sulfur Batteries

“…[ 23,24 ] To overcome current cathode limitations, metal‐based compounds and metal‐organic frameworks have been added to strengthen the chemical interaction with LiPS and reduce the shuttle effect. [ 25–30 ] Among the tested metal compounds, sulfides such as MoS 2 , VS 2 , CoS 2 , Ni 3 S 2 , and Sb 2 S 3 , have demonstrated particularly strong sulfiphilic ability toward LiPS trapping and low lithiation voltages. [ 31–36 ] However, cathodes based on metal sulfides are generally characterized by moderate electrical conductivities, limited sulfur utilization, insufficient cycling stability, and low rate capabilities.…”

Recent Breakthroughs in the Bottleneck of Cathode Materials for Li–S Batteries

“…Therefore, combining the excellent properties of MoS 2 with other materials can solve the problem of low conductivity . 3D Co-MoS 2 -graphene synthesized by the hydrothermal method could not only alleviate the shuttle effect of the cathode material but could also increase the conduction of electrons and the transfer of Li + (Figure ). The doping of metal Co promoted the transformation of the properties of MoS 2 from the semiconductor to the metal phase.…”

“…(c) Charge/discharge profiles at different current densities of Co-MoS 2 -G/S. Reproduced from ref . Copyright 2021, American Chemical Society.…”

Exploration of the Unique Structural Chemistry of Sulfur Cathode for High‐Energy Rechargeable Beyond‐Li Batteries

“…[116,117] Due to high electrical conductivity, single metal atoms expedite the electrokinetics of polysulfides conversion from long-chain to short-chain polysulfides. [118] It is identified that the metal atoms can lower the decomposition energy barrier of polysulfides due to higher polar-polar interactions and physical/chemical adsorption that speed up the redox kinetics of the battery. [119] In recent years, nanoclusters of various transition metals, for instance, iron, copper, vanadium, and nickel, have been reported to attenuate the dissolution of sodium polysulfides.…”