Anion Design-Enabled High-Performance Cobalt-Based 3D Conductive Interlayers to Suppress the Shuttle Effect for Lithium–Sulfur Batteries

Abstract

Recently, transition-metal compounds (TMCs) with unique adsorptive and catalytic properties have shown great promise in lithium–sulfur (Li–S) batteries to inhibit the shuttle effect. However, current studies mostly focus on the morphology control of one specific TMC, while the relationship between the composition and performance is insufficiently revealed. Nevertheless, the polarity and catalytic activity are largely dependent on the components of TMCs, especially the anion species. Herein, we take Co–X (X = O, P, and S) compounds as example compounds and systematically investigate the compositional effects of Co–X compounds on their inhibition abilities for the shuttle effect. To conduct the investigation, CoS2, CoP, and Co3O4 flowers with identical morphologies and nanostructures were successfully grown on 3D conductive self-supporting carbon nanofibers (CNFs) via a facile electrospun method combined with post-heat treatment. When tested in Li–S batteries, the CoS2/CNF interlayer outperforms its phosphide and oxide counterparts, displaying the strongest adsorption ability and the highest catalytic activity toward polysulfides. Impressively, Li–S batteries coupled with CoS2/CNF interlayers exhibit outstanding electrochemical performance with a high specific capacity of 1115.2 mA h g–1 and enhanced cycling stability of 884.4 mA h g–1 after 200 cycles. We believe such an anion design strategy could open a new avenue for constructing high-performance Li–S batteries.

A Heterostructured Gel Polymer Electrolyte Modified by MoS2 for High-Performance Lithium–Sulfur Batteries

“…The rapid development of portable electronic devices has increased the demand for electric energy and has also stimulated the development of rechargeable batteries that have high energy density . Lithium–sulfur batteries have attracted much attention due to their environmental protection, abundant reserves, and extraordinary theoretical specific capacity (1675 mAh g –1 ) and ultrahigh energy density (2600 Wh kg –1 ). , However, Li–S batteries have faced enormous challenges because of the insulating nature of sulfur, large volume changes, and the “shuttle effect”. , The shuttle effect in particular results in an irreversible loss of active substance, an attenuation of battery life, and a low Coulomb efficiency. − In order to solve this problem, researchers have made great efforts on the solid-state of electrolytes. − All-solid-state electrolytes have significant safety advantages and wide electrochemical windows. − However, their insufficient ionic conductivity , and unsatisfactory interface contact greatly limit their utilization in lithium–sulfur batteries. As for gel electrolytes, they have the advantages of liquid electrolytes and the high safety of solid electrolytes. , At present, the focus of gel electrolytes is to design the composition and structure of a chain segment of the polymer matrix in order to prevent the permeation of polysulfide lithium (LiPS), such as by relying on the electrostatic repulsion of ionizable groups, , introducing strongly adsorbing groups, , etc.…”

Regulating Electrocatalytic Polysulfides Redox Kinetics through Manipulating Surface Electronic Structure of Molybdenum-Based Catalysts for High-Performance Lithium-Sulfur Batteries

“…Lithium-sulfur (Li-S) battery is the most promising candidate for high-efficiency energy storage devices due to the high theoretical specific capacity of the cathode (1672 mAh g –1 ) and energy density of about 2600 Wh kg –1 , as well as abundant resources and environment-friendly sulfur. − Unfortunately, the intrinsic insulative properties of sulfur and lithium sulfides (Li 2 S 2 /Li 2 S), large volume expansion (78%) of the cathode during the charge/discharge process, particularly the serious ″shuttle effect″ of soluble lithium polysulfides (LiPSs) mediators, and the sluggish solid–liquid–solid conversion kinetics of sulfur species make it impossible to guarantee its life span, which impedes the further development of Li-S batteries. − Using electrocatalysts has recently been mentioned as the most powerful strategy to fundamentally solve the intractable issues above. − They can effectively accelerate the electrocatalytic transformation and improve the electrochemical performance of Li-S batteries.…”