Interface Design and Development of Coating Materials in Lithium–Sulfur Batteries

Abstract

High-energy Li-S batteries have received extensive attention and are considered to be the most promising next-generation electric energy storage devices beyond Li-ion batteries. Interface design is an important direction to address challenges in the development of Li-S batteries. This review summarizes recently developed coatings and interlayer materials at various interfaces of Li-S batteries. In particular, advanced nanostructures and novel fabrication methods of coating and interlayer materials applied to Li-S batteries are highlighted. Furthermore, underlying mechanisms at the interfaces and electrochemical performance of the developed Li-S batteries are also discussed. Finally, existing challenges and the future development of interface design in high-energy Li-S batteries are summarized and prospected.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201801323. and the mechanical damage of electrode caused by the volume expansion induces a rapid decrease of battery capacity. In terms of the anode, most Li-S batteries still use lithium metal which poses challenges of both safety and performance in Li-S batteries. [5] First, side reactions triggered by polysulfides and the surrounding electrolyte consume lithium metal quickly and form an insulated interlayer on the lithium metal, which damages the Li anode structure and blocks Li/Li + transformation. [2a,6] Second, similar to Li-ion batteries, lithium anodes suffer from the inevitable growth of lithium dendrites, which poses safety concerns in Li-S batteries. [7] As a result, all of these challenges hinder the development of high-energy Li-S batteries in practical applications. [8] A number of researchers and scientists have devoted relentless effort to address the challenges of Li-S batteries, such as the development of various carbon hosts, engineering the electrode structure, optimization of electrolytes, as well as coupling with high-energy anode materials. [1c,2c,3c,9] Among the recent literature, the investigation and modification of interfaces via coating and interlayer materials are very promising and prevailing strategies in Li-S batteries. [1c,2c,3c,10] As shown in Figure 1b-d, this review is divided into three parts based on different interface areas, which are the interfaces at i) sulfur cathodes, ii) separators, and iii) lithium anodes. Based on the issues at different interfaces, various design principles and requirements of coating and interlayer materials are developed. This review summarizes the study of interface design with coating and interlayer materials for Li-S batteries at different interfaces. The content covers structure design, synthetic approach, electrochemical performance, reaction mechanisms, as well as future perspectives of coating materials applied to Li-S batteries. Interface Design on Sulfur-Based Cathodes in Li-S BatteriesDissolution of polysulfides in organic liquid electrolytes and accompanied "shuttle effect" side reactions are severe challenges of c...

Graphene Oxide/Carbon Nanotube Bilayer Flexible Membrane for High‐Performance Li–S Batteries with Superior Physical and Electrochemical Properties

“…[8] In order to secure cost effectiveness, lithium-sulfur (Li-S) batteries have been considered one of the most attractive energy storage systems because of their high theoretical capacity (1672 mAh g −1 ), energy density (2600 Wh kg −1 ), nontoxicity, low cost, and the natural abundance of sulfur. [11,12] To resolve these issues, most studies have focused on fabricating an inhibitor to trap the lithium polysulfides in the cathode side through chemical/physical adsorption, such as the interlayer inserted between the sulfur electrode and the separator with a metal oxide, [13][14][15] conductive carbon material, [16] polymers, [17][18][19][20][21][22] Al 2 O 3 , [23][24][25][26] Ni foam, [27,28] CoS 2 , [29,30] and metal carbide. In particular, the shuttle phenomenon is caused by the high solubility of the lithium polysulfide intermediate (Li 2 S X , 2 < X ≤ 8) in the electrolyte.…”

Recent Advances in Hollow Porous Carbon Materials for Lithium–Sulfur Batteries

“…During the charge/discharge process, the side reactions between Li metal anode and liquid electrolyte (i.e., the electrolyte decomposition at the anode side) not only increase the consumption of electrolyte and lithium, but also generate the gaseous products during the cycling process . With a better understanding of Li–S chemistry, some strategies, including designing the sulfur‐hosting materials, tuning the electrolyte's properties, introducing a polysulfide barrier layer, and regulating the Li nucleation/growth behaviors, have been proposed and assessed in recent years. These effective strategies have fueled an explosive development of Li–S battery research, and considerable improvements of the capacities and cycling stabilities of Li–S batteries have been made …”

Ionic Liquids and their Polymers in Lithium‐Sulfur Batteries

“…Moreover, the use of highly abundant sulfur (S 8 ) in the cathode makes the battery design more cost effective in comparison to the transition metal based oxides used in LIBs . Despite this fact, there are other obstacles that hinder the application of Li−S batteries …”

“…[6] Despite this fact, there are other obstacles that hinder the application of LiÀS batteries. [3,[7][8][9][10][11][12] A typical LiÀS battery is composed of a Li-metal anode, S 8 /C composite cathode (most often the C is a porous carbon host), a separator, and a liquid or solid electrolyte (Figure 1). During the discharge process the S 8 is reduced from elemental S 8 to Li 2 S in a stepwise fashion through various polysulfide intermediates.…”