Self-Assembled 3D MnO₂ Nanosheets@Delaminated-Ti₃C₂ Aerogel as Sulfur Host for Lithium–Sulfur Battery Cathodes

Dissolution of lithium polysulfides (LiPSs), volume expansion, and the insulative nature of elemental sulfur are the major challenges for high-performance lithium sulfur batteries (LSBs). To mitigate these adverse effects, we developed a 3D MnO2 nanosheets@delaminated-Ti3C2 (MNSs@d-Ti3C2) aerogel framework via an electrostatic self-assembly approach, which proves to be a good sulfur host for high-performance LSBs. In the MNS@d-Ti3C2 aerogel, the high specific surface area and mesoporous structure benefit the high sulfur loading; the synergistic effect of the d-Ti3C2 and the polar MnO2 provides a robust conductive pathway and promotes the LiPSs’ adsorption and thus can effectively facilitate electron transport and strengthen the capture ability to confine the LiPSs in the cathode. As a result, the cathode based on MNSs@d-Ti3C2/S composite exhibits a high active-sulfur utilization (initial discharge capacity of 1140 mA h gS–1), good rate capacity (reversible capacity of 615 mA h gS–1 at 2.0 C), outstanding specific discharge capacity, and superior capacity retention (only 0.06% capacity decay per cycle over 500 cycles at 1.0 C, even at sulfur loadings up to 3.7 mg cm–2).