20. MXene Materials as Electrodes for Lithium-Sulfur Batteries

Exploration of new electrochemistries that go “beyond lithium-ion” to boost energy density and reduce cost is rapidly gaining momentum. In this pursuit, lithium-sulfur (Li-S) batteries that couple sulfur-positive electrodes (or “cathodes”) with lithium-negative electrodes (or “anodes”) are considered particularly promising candidates. The Li-S battery has received enormous attention in the past decade, due to the high theoretical specific energy (Wh kg⁻¹) and earth abundance of sulfur, which is coupled with a high-energy density Li metal anode in the cell. Instead of intercalation chemistry, these batteries rely on conversion chemistry, which yields a high theoretical capacity. MXenes can provide a vital role. MXenes have been used in Li-S batteries. Delaminated MXenes are capable of high electronic conductivity and exhibit rich surface properties, which synergistically improves the electron transport properties of the sulfur electrode and provides chemical interactions with lithium polysulfides. Another advantageous aspect is MXenes denser structure compared to most “fluffy” carbonaceous materials, which benefits the volumetric energy density of the battery. This chapter provides a brief overview of the recent development of MXenes for Li-S batteries, from material aspects on tuning the physical and electrochemical properties of the sulfur cathode to their performance in prototype cells.