High Energy Density Sulfur‐Rich MoS6‐Based Nanocomposite for Room Temperature All‐Solid‐State Lithium Metal Batteries

Abstract The all‐solid‐state lithium–sulfur battery is considered to be a promising energy device due to high energy density and excellent safety. However, sulfur suffers from its insulating nature and large volume changes. Employing transition‐metal sulfide cathodes is an attractive alternative. Herein, a high energy density sulfur‐rich MoS 6 ‐based nanocomposite is designed, where MoS 6 nanospheres are homogenously anchored on carbon nanotubes (CNTs) by a wet‐chemical method, providing improved electronic conductivity and reduced volume changes. In addition, a nanosized Li 7 P 3 S 11 electrolyte is in situ coated on the surface of MoS 6 ‐CNT20 to realize intimate interface contact and form nanoscale electronic/ionic transportation networks. The resultant MoS 6 ‐CNT20@15%Li 7 P 3 S 11 composite shows high electronic conductivity (1.7 × 10 −1 S cm −1 ) and ionic conductivity (6.7 × 10 −4 S cm −1 ), which are eight and three orders of magnitude improved compared to those of MoS 6 . The Li/Li 6 PS 5 Cl/MoS 6 ‐CNT20@15%Li 7 P 3 S 11 battery exhibits an initial discharge capacity of 1034.32 mAh g −1 at 0.1 A g −1 . In addition, an ultrahigh reversible energy density of 1640 Wh kg −1 for the active material can be realized, which is the highest among all transition‐metal sulfide cathodes. Moreover, it shows a reversible capacity of 550.00 mAh g −1 at 0.5 A g −1 after 1000 cycles, demonstrating that the sulfur‐rich MoS 6 ‐based nanocomposite is a promising highenergy density cathode material for next‐generation all‐solid‐state lithium batteries.