CO₂-Oxidized Ti₃C₂T_x–MXenes Components for Lithium–Sulfur Batteries: Suppressing the Shuttle Phenomenon through Physical and Chemical Adsorption

Abstract

Lithium–sulfur (Li–S) batteries are one of the main challenges facing Li-ion technology because the insulating nature of sulfur and the shuttle phenomenon of dissolved lithium polysulfides (LPSs) in liquid electrolytes result in critical problems, including low Coulombic efficiency, loss of active material, and rapid capacity decay. Here, we oxidized delaminated transition metal carbides (MXenes) using CO2 (Oxi-d-MXenes) and used them as both cathode electrode with sulfur and modified separator coated onto the glass fiber without a conductive material and binder to suppress the diffusion of LPSs. Oxi-d-MXenes annealed at 900 °C using CO2 gas formed perfectly converted rutile-TiO2 nanocrystalline particles on their two-dimensional sheets. Li–S batteries fabricated with the Oxi-d-MXenes cathode and the Oxi-d-MXenes-modified separator exhibited high Coulombic efficiency (nearly 99%) and retained a capacity of about 900 mAh g–1 after 300 cycles at a current density of 1C. These results were attributed to the chemical and physical adsorption between the Oxi-d-MXenes and the LPSs. Our results imply that Oxi-d-MXenes prepared by the CO2 treatment exhibit physical and electrochemical properties that enhance the performance of Li–S batteries.

3D Ordered Porous Hybrid of ZnSe/N‐doped Carbon with Anomalously High Na+ Mobility and Ultrathin Solid Electrolyte Interphase for Sodium‐Ion Batteries

“…The volume expansion and formation of the SEI film are the main reasons for capacity loss in the first cycle. [ 51 ] Additionally, the 3DOHP ZnSe@N,C hybrid provides specific capacities of 391.5, 330.7, 284.7, 290.8, 281.2, 265.4, 245.6, 238.7, and 179.9 mAh g −1 at 0.1, 0.2, 0.4, 0.5, 1, 2, 4, 5, and 10 A g −1 (Figure 6c). Even the current densities increase to 20 and 30 A g −1 , it still delivers specific capacities of 174.9 and 157.4 mAh g −1 , respectively.…”

A hierarchically porous TiO2@C membrane with oxygen vacancies: a novel platform for enhancing the catalytic conversion of polysulfides

“…33 After polysulfide adsorption, some electrons are transferred from polysulfides to Ti atoms, resulting in reduced interactions between the nuclei and extranuclear electrons of Ti atoms, with the typical characteristic peaks shifting to lower energies. 34 Meanwhile, the fitted S 2p spectrum proves the existence of thiosulfate and polythionate,…”

Recent Advances and Strategies toward Polysulfides Shuttle Inhibition for High‐Performance Li–S Batteries

“…The Cu 2 (CuTCPP)-modified separator obtained a capacity retention rate as high as 71.1% after 900 cycles at 1C with a high sulfur loading of 10 mg cm −2 . Recently, a CO 2 -oxidized Ti 3 C 2 T x -MXenes component was proposed for sulfur host and separator coating material by Lee et al [153] The CO 2 -oxidized MXenes consisted of 2D carbide flakes with a rutile-TiO 2 crystal structure and the Ti sites show strong chemical affinity toward LiPSs, and the shuttle behavior of soluble LiPs are inhibited effectively by the synergistic effect of physical and chemical adsorption.…”