About this Research Topic
The ever-increasing demand for high-energy applications such as electric vehicles and smart grids is requiring the development of new battery systems with lower cost and higher energy density than those offered by the current lithium ion batteries. Due to the high theoretical energy density and the low cost of sulfur feedstock, lithium-sulfur batteries have been considered promising and have achieved substantial progress over the past decades. Unlike the conventional Li-ion chemistry based on intercalation chemistry of transition metal oxides, sulfur cathodes involve complicated phase transitions, such as reduction of solid sulfur to liquid polysulfides and further to solid lithium sulfides during discharge, and vice versa. The lithium polysulfide molecules are ready to dissolve in electrolyte and shuttle between the anode and cathode, leading to rapid capacity fade and other severe consequences. To effectively trap and facilitate polysulfides redox reactions, electrocatalysis has been proposed. The oxidation of lithium sulfide during charging can also be manipulated by using electrocatalysts. However, many challenges still remain in developing multifunctional electrocatalysts to meet obstacles from both anodes and cathodes during charge and discharge for practical lithium-sulfur batteries.
On the other hand, based on its similar electrochemistry, low-cost sulfur cathode is also ready to be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, zinc, and aluminum, to form new metal-sulfur systems. They can potentially further decrease the production cost and/or improve the energy density of sulfur-based batteries; nonetheless, research in this field are still at an infant stage.
The intention of this Research Topic is to offer a forum for the community to discuss the critical interfacial reactions at the electrocatalyst in the context of lithium-sulfur battery and other cutting-edge research fields of post lithium-sulfur batteries. The issue encourages efforts on both synthesizing advanced materials to improve battery performance, and disclosing fundamental insights through novel characterizations. Critical questions that we wish to highlight in this topic include, but are not limited to:
• How the electrocatalytic materials control the polysulfides reduction and oxidation during discharge and charge
• What happens at the electrocatalyst/sulfur species interface at the atomic level during cycling
• How to predict electrocatalysis to enhance the electrochemical performance of the metal-sulfur systems
• How to design electrocatalysts to enable metal-sulfur batteries with reliable electrochemical performance, satisfying practical application requirements
Other themes beyond the aforementioned questions are also welcome if they can offer new insights related to the materials, electrochemistry, characterization, and system engineering of metal-sulfur systems.
Keywords: rechargeable batteries, sulfur cathodes, metal anodes, electrocatalyst
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