Dual-Functional V<sub>2</sub> C MXene Assembly in Facilitating Sulfur Evolution Kinetics and Li-Ion Sieving toward Practical Lithium-Sulfur Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 36934318.
- Also identified by DOI 10.1002/adma.202300771.
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Abstract
Lithium-sulfur (Li-S) batteries are considered as one of the most promising candidates to achieve an energy density of 500 Wh kg⁻<sup>1</sup> . However, the challenges of shuttle effect, sluggish sulfur conversion kinetics, and lithium-dendrite growth severely obstruct their practical implementation. Herein, multiscale V<sub>2</sub> C MXene (VC) with a spherical confinement structure is designed as a high-efficiency bifunctional promotor for the evolution of sulfur and lithium species in Li-S batteries. Combining synchrotron X-ray 3D nano-computed tomography (X-ray 3D nano-CT), small-angle neutron scattering (SANS), and first-principle calculations, it is revealed that the activity of VC can be maximized by tuning the scale, and the as-attained functions are conducted as follows: (i) the VC acts as the efficient lithium polysulfide (LiPS) scavenger due to the large number of active sites; (ii) the VC exhibits significantly improved electrocatalytic function for the Li<sub>2</sub> S nucleation and decomposition reaction kinetics owing to the scale effect; and (iii) the VC can regulate the dynamic behavior of Li-ions and thus stabilize the lithium plating/stripping effectively on account of the unique ion-sieving effect.