Synthesis of Carbon/Sulfur Nanolaminates by Electrochemical Extraction of Titanium from Ti₂SC

Abstract

Herein we electrochemically and selectively extract Ti from the MAX phase Ti2SC to form carbon/sulfur (C/S) nanolaminates at room temperature. The products are composed of multi-layers of C/S flakes, with predominantly amorphous and some graphene-like structures. Covalent bonding between C and S is observed in the nanolaminates, which render the latter promising candidates as electrode materials for Li-S batteries. We also show that it is possible to extract Ti from other MAX phases, such as Ti3AlC2, Ti3SnC2, and Ti2GeC, suggesting that electrochemical etching can be a powerful method to selectively extract the "M" elements from the MAX phases, to produce "AX" layered structures, that cannot be made otherwise. The latter hold promise for a variety of applications, such as energy storage, catalysis, etc.

Controllable Chain‐Length for Covalent Sulfur–Carbon Materials Enabling Stable and High‐Capacity Sodium Storage

“…As shown in Figure 6a,d, XPS measurements are carried out on the SC-BDSA felt at intermediately discharged (0.8 V), fully discharged (0.01 V), intermediately discharged (0.8 V), and fully charged states (3.0 V), respectively. [29,31] As expected, after charging to 0.8 V (Figure 6c), the majority of S 2− is oxidized to long-chain states with higher binding energies. And spin-orbit coupling gives rise to a doublet in the S 2p peak (2p 1/2 -2p 3/2 ).…”

“…In addition, it was suggested that the polar-polar interaction is a strong chemical interaction between polar sodium polysulfides and polar host materials. [28][29][30][31] In practice, these oxide and sulfide materials are able to bridge sodium polysulfides through both polar-polar Na-S(O) interaction and Lewis acid-base bonding, depending on the exposed facets to some extent. [25][26][27] Instead of relying on polar-polar interactions, the suitably tailored hosts can bind sodium polysulfides through metal-sulfur bonding.…”

Designing Host Materials for Sulfur Cathodes: From Physical Confinement to Surface Chemistry

“…[13] Additionally,Gogotsi and co-workers have developed as elective electrochemical extraction method to fabricate new laminated materials, filling the gap in material composition between pure inorganic materials and carbon materials. [14] Compared to systems employing the physical-confinement technique,t he above highlighted MNCS/CNT and MXene systems exhibited remarkable enhancements of both capacity and cycling stability.Ahigh initial capacity of 1438 mAh g À1 was obtained at ac urrent density of 0.84 mA cm À2 for MNCS/CNT composites with 70 %o f sulfur.T he system also demonstrated excellent cycling stability as after 200 cycles as pecific capacity of approximately 1200 mAh g À1 was retained at ac urrent density of 1.68 mA cm À2 .Furthermore,the system exhibits ahigh sulfur loading of 5mgcm À2 . [15] Considering the MXene d-Ti 2 Chosts, their composites with 70 %ofsulfur demonstrated adischarge capacity of 1090 mAh g À1 at current density 0.84 Ag À1 and al ow decay rate of 0.05 %p er cycle over the course of 650 cycles.…”

Facile Synthesis of Crumpled Nitrogen‐Doped MXene Nanosheets as a New Sulfur Host for Lithium–Sulfur Batteries

“…[14] MXene family members could be good candidate electrode material for lithium-sulfur batteries. [15] Nazar and co-workers investigated Ti 2 C(OH) x /S cathodes. [15] Nazar and co-workers investigated Ti 2 C(OH) x /S cathodes.…”

“…Both precursors show a sharp mass loss in the temperature range of 240-300 °C. [15] Figure S6 in the Supporting Information shows the TEM image of etched-Ti 3 C 2 T x sample after hydrofluoric acid treatment. [18] It should be noted that the mass loss rate of the self-assembled precursor at this stage is lower than that of the mechanically mixed precursor.…”