About this Research Topic
The rapid development of personal electronics and electric vehicles requires energy storage systems with very high energy density. Lithium-sulfur batteries are considered to be the next generation energy storage systems due to their superior theoretical energy density up to 2600 Wh kg-1, cost-effective raw materials, and environmental benignity. Different from batteries with intercalation chemistry, Li-S batteries experience dissolution and diffusion of reaction intermediates (lithium polysulfides, Li2Sx, 2 < x < 8) in the electrolyte. This behavior can lead to a polysulfide shuttling effect and loss of active material from the cathode, resulting in capacity fading and poor coulombic efficiency. Other obstacles exist in the insulating nature of the Sulfur and Li2S as the charge and discharge products, the volume expansion in between the charge and discharged state, Li metal anode with dendrite formation and mossy lithium deposit, which induce low efficiency and safety risks, and therefore hinder the practical application of Li-S batteries. Abundant research endeavors have been poured into this area and significant progress has been made recently, from the viewpoint of chemistry, physics, materials, and engineering. Different materials and structures have been explored as the polar hosts to absorb and immobilize the lithium polysulfides in Li-S battery in order to decrease the dissolution of the long-chain polysulfides and thus avoid the shuttle effect during charge-discharge. New insights into the surface chemistry have also been enabled by combining controlled synthesis of materials, advanced structural characterizations, electrochemical studies, and computational simulations.
Based on the literature and our experience, however, key parameters are required to realize Li-S battery with energy density of 500 Wh kg-1, such as i) sulfur content higher than 80 wt%; ii) sulfur mass loading higher than 8 mg cm-2; iii) sulfur cathode with capacity higher than 1000 mAh g-1 at 0.2 C rates; iv) electrolyte/sulfur ratio less than 3. Targeting high energy density of Li-S batteries, novel trapping chemistry and cathode design with lean electrolyte and high sulfur loading should to be overcome gradually.
This Research Topic “Surface Chemistry and Materials Design in Lithium-sulfur Batteries” is therefore launched aiming at the forefront research in this exciting area with widespread topics, ranging from sulfur trapping chemistry, novel structures, materials design, electrolyte, separator, lithium metal protection, the interfaces between electrolyte and electrode to advances in characterization, cell configurations, and mechanistic insights for Li-S batteries.
Keywords: Lithium-sulfur batteries, Lithium metal protection, Sulfur electrode, Catalysis, Interfacial design
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