Solar Cells: Facile Synthesis of Crumpled Nitrogen‐Doped MXene Nanosheets as a New Sulfur Host for Lithium–Sulfur Batteries (Adv. Energy Mater. 13/2018)

Abstract

In article number https://doi.org/10.1002/aenm.201702485 Dan Wang and Guoxiu Wang and co‐workers design a novel strategy for doping heteroatomic nitrogen into MXene frameworks. The resultant nitrogen‐doped MXene nanosheets demonstrate a well‐defined porous structure, a high surface area and large pore volume. The nitrogen‐doped porous MXene nanosheets are successfully used for strong physical and chemical co‐absorption of polysulfides. Lithium‐sulfur batteries, based on porous N‐doped MXene nanosheets/sulfur composites, exhibit an outstanding electrochemical performance.

Compactly Coupled Nitrogen‐Doped Carbon Nanosheets/Molybdenum Phosphide Nanocrystal Hollow Nanospheres as Polysulfide Reservoirs for High‐Performance Lithium–Sulfur Chemistry

“…The existence of N species results from the carbonization of dopamine. N doping in MoP@C/N HCSs can further strengthen the chemical binding polysulfides to inhibit the shuttling effect of sulfur electrodes for the development of high energy density Li–S batteries …”

“…Despite these tempting properties, their practical applications are still plagued by several serious obstacles, such as incomplete utilization of insulating sulfur, troublesome shuttling effect of soluble polysulfides (Li 2 S n , 4 ≤ n ≤ 8), and large volume expansion of sulfur (≈80%), resulting in low practical energy density and rapid capacity fading during the battery cycling . With the purpose of overcoming these issues, numerous efforts have been dedicated to improving the electrochemical performance of Li–S batteries by some typical strategies, such as physical confinement and chemical binding of sulfur species into diverse host materials (e.g., hollow carbon nanomaterials, metallic compounds,) separator/interlayer design, multifunctional polar binders, electrolyte modification, and lithium anode protection . Although these sulfur‐hosting composites have been proved to efficiently inhibit polysulfides shuttling between the cathode and the lithium anode, their low sulfur content in cathode leads to their energy density cutting in half at most compared with the pure sulfur/carbon black (CB) cathode with relatively high sulfur loading (70 wt%) .…”

Highly Enhanced Pseudocapacitive Performance of Vanadium‐Doped MXenes in Neutral Electrolytes

“…Hence, in order to improve the pseudocapacitance of MXenes in neutral electrolytes, it is vital to increase the adsorption strength between adsorbates (typically, Li + , Na + , or K + ions) in aqueous electrolyte and the surface functional groups of MXene (O and OH groups) by surface electronic engineering. In this regard, heteroatom doping has been proved to be an efficient way of tuning the surface activity . Among available dopants, vanadium has been reported as a viable choice for doping transition metal carbides due to its atomic size similar to Ti and better interaction with alkali metal ions …”

Radiation‐Induced Self‐Assembly of Ti3C2Tx with Improved Electrochemical Performance for Supercapacitor

“…And with the increase of absorbed doses from 10 to 20 kGy, a crumpled structure of SA‐Ti 3 C 2 T x ‐20 with a lateral dimension of over ten micrometers can be observed clearly in Figure 2c. It is proposed that surface charge characteristics and interaction among surface groups of SA‐Ti 3 C 2 T x may play prominent roles in the self‐assembly process of sheets and the formation of crumpled structure . Furthermore, the unique crumpled structure can improve the specific surface area and prevent the restacking of MXene layers, it can also increase the electrochemical active sites and make the diffusion and contact of electrolyte ions more convenient, which is favorable to the improvement of the electrochemical properties.…”