Enveloping Ultrathin Ti3C2 Nanosheets on Carbon Fibers: A High-Density Sulfur Loaded Lithium-Sulfur Battery Cathode with Remarkable Cycling Stability
A Ti3C2@CF sulfur host material has been prepared by enveloping 3D carbon fibers (CF) with isolated 2D ultrathin Ti3C2 nanosheets, which largely avoids the nanosheets restack and significantly improves the exposure degree of the 2D surface. This material allows uniform thin-layer loading of sulfur at a high density of 4 mg·cm-2 without loss on the electrode conductivity. The Ti3C2 nanosheets form strong bonding with lithium polysulfides to inhibit shuttling. Also, the flexible Ti3C2 enveloping greatly enhances the ductility of CF, which successfully withstands the stress and distortion caused by volume expansion, and thus avoids the pulverization of the cathode. The resulting Li-S battery gives remarkable cycling stability by showing a negligible capacity fading rate (0.06 % per cycle over the first 200 cycles at 0.5 C) and a greatly remained cycle capacity (626.0 mAh·g-1 after 1000 cycles at 1 C).