12/16/2023 0 Comments 5.45 find the anchoring forces(1−7) However, the shuttle effect hinders the charge and discharge process. The uniform charge distribution on the Ti 2CS 2 surface contributes to the fast Li diffusion.īecause of the high theoretical capacity (1675 mA h g –1) and energy density (2600 W h kg –1), lithium–sulfur (Li–S) batteries have been considered as one of the most promising systems for the next generation high-energy rechargeable lithium batteries. ![]() The great affinity of the Ti 2CS 2 surface to the product Li 2S leads to facile polysulfide conversion. More importantly, the origin for the Ti 2CS 2 surface with medium adsorption ability represents the fastest polysulfide conversion, and Li diffusion is further clarified. Accordingly, because of the medium binding energy, good electronic conductivity, and fast polysulfide conversion and Li diffusion, Ti 2CS 2 is revealed to be the favorable functionalized surface. In addition, for the kinetic conversion ability, the Ti 2CS 2 surface has the fastest polysulfide conversion and Li diffusion, followed by Ti 2CF 2, and Ti 2CO 2 represents the slowest conversion and diffusion. Meanwhile, the narrow-band gap semiconductor property of Ti 2CO 2 during adsorption indicates worse electronic conductivity than metallic Ti 2CS 2 and Ti 2CF 2. Ti 2CO 2 has the largest surface adsorption energy, followed by Ti 2CS 2, and Ti 2CF 2 is the weakest. It is found that compared with severe polysulfide deformation on pristine Ti 2C and Ti 2C(OH) 2 surfaces, Ti 2CO 2, Ti 2CS 2, and Ti 2CF 2 have effective polysulfide adsorption. In the present work, a theoretical study based on density functional theory has been carried out to clarify the favorable functionalized surface by comparing pristine Ti 2C and −OH-, −S-, −F-, and −O-functionalized Ti 2C surfaces from the aspects of adsorption ability, electronic conductivity, and kinetic conversion ability. The complex surface functionalization (such as −OH, −S, −F, and −O) of MXenes boosts the performance but also causes controversies about the favorable functionalized surface in the electrochemical reaction during the charge and discharge process. Because of the high specific surface area, excellent electronic conductivity, facile Li diffusion, and rich functional groups, Ti 2C-based MXenes have been widely used to improve the electrochemical property of lithium–sulfur batteries.
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