Nanoconfined Topochemical Conversion from MXene to Ultrathin Non‐Layered TiN Nanomesh toward Superior Electrocatalysts for Lithium‐Sulfur Batteries

Abstract 2D non‐layered materials (2DNLMs) featuring massive undercoordinated surface atoms and obvious lattice distortion have shown great promise in catalytic/electrocatalytic applications, but their controllable synthesis remains challenging. Here, a new type of ultrathin carbon‐wrapped titanium nitride nanomesh (TiN NM@C) is prepared using a rationally designed nano‐confinement topochemical conversion strategy. The ultrathin 2D geometry with well‐distributed pores offers TiN NM@C plentiful exposed active sites and rapid charge transfer, leading to outstanding electrocatalytic performance tackling the sluggish sulfur redox kinetics in lithium‐sulfur batteries (LSBs). LSBs employing TiN NM@C electrocatalyst deliver excellent rate capabilities (e.g., 304 mAh g −1 at 10 C), greatly outperforming that of using TiN nanoparticles embedded in carbon nanosheets (TiN NPs@C) as a benchmark. More impressively, a free‐standing electrode for LSBs with a high sulfur loading of 7.3 mg cm −2 is demonstrated, showing a high peak areal capacity of 5.6 mAh cm −2 at a high current density of 6.1 mA cm −2 . This work provides a new avenue for the facile and controllable fabrication of 2DNLMs with impressive electrocatalysis for LSBs as well as other energy conversion and storage technologies.