Crystal Facet Engineering of MXene‐Derived TiN Nanoflakes as Efficient Bidirectional Electrocatalyst for Advanced Lithium‐Sulfur Batteries

Abstract

The design of nanomaterials with grain orientation structure by crystal facet engineering is of great significance for boosting the catalytic ability and electrochemical properties, but the controllable synthesis is still a challenge. Here, TiN nanoflakes with exposed (001) facets are prepared using 2D Ti3C2 MXene as the initial reactant and applied as a bidirectional electrocatalyst for the reduction and oxidation process in lithium‐sulfur batteries (LSBs). The (001) facet‐dominated TiN nanoflakes have a strong adsorption capacity for soluble lithium polysulfides (LiPSs). More importantly, theoretical calculations and experiment results confirm the (001) facet‐dominated TiN nanoflakes catalyze the conversion of soluble LiPSs to Li2S2/Li2S to induce the Li2S uniform deposition in the discharge process and decrease the delithiation barrier of Li2S in the charge process. Therefore, the excellent electrochemical properties of LSBs are achieved, which demonstrates a high discharge capacity of 949 mAh g−1 at 1 C and maintains high capacity reversibility with a decay rate of 0.033% per cycle after 800 cycles.

Engineering strategies and active site identification of MXene-based catalysts for electrochemical conversion reactions

“…In particular, TiN nanoflakes with exposed (001) facets derived from Ti 3 C 2 MXene catalyzed both the discharge and charge processes in Li-S batteries to facilitate the conversion of soluble lithium polysulfides to Li 2 S 2 /Li 2 S and decomposition of Li 2 S, respectively. 383 Another MXene analogue of Mo 5 N 6 as cathode material was reported to boost the performance of Na-S batteries (Fig. 20g).…”

Advanced two‐dimensional materials toward polysulfides regulation of metal–sulfur batteries

“…Since then, numerous nanostructured nitrides as sulfur cathodes are well developed, resulting in significant improvements in cycle performance. Over more recent times, titanium nitrides (TiN) hold great interest to be implemented as sulfur anchoring sites which deliver a much stable cycling span 150–153 . Zhang group proposes a multifunctional titanium nitride separator to retard polysulfides dissolution, fabricated by a simple coating process (Figure 10A).…”

Design and synthesis of novel pomegranate-like TiN@MXene microspheres as efficient sulfur hosts for advanced lithium sulfur batteries

“… 27 Peng et al prepare MXene-derived TiN nanoflakes as sulfur host and study the catalytic action, which demonstrate that the (001) facet-dominated TiN nanoflakes have a strong adsorption capacity for LiPSs. 28 Nevertheless, only a few studies about TiN with hollow structure applied as sulfur hosts have been reported due to the limited preparation strategies and technologies. Therefore, the design of MXene/TiN composite materials with more edge sites can accelerate electron/ion transport, improve the catalytic effect of the material on LiPSs, and further improve the utilization rate of the active substance sulfur.…”