An amorphous niobium polysulfide based nanocomposite enables ultrastable all-solid-state lithium batteries

Abstract

Transition metal sulfide cathodes have attracted much attention in all-solid-state lithium batteries due to their high theoretical specific capacity. However, the low ionic/electronic conductivities and volume expansion of sulfide cathodes are great challenges for their practical application. In this work, an amorphous NbS_4.5 (a-NbS_4.5) based nanocomposite cathode is designed for all-solid-state lithium batteries. Combining with Super P, the electronic conductivity of a-NbS_4.5 is improved and volume changes are suppressed. Further coupling with Li₇P₃S₁₁ solid electrolyte, both interfacial contact and ionic conductivity are enhanced. As a result, the all-solid-state batteries using the a-NbS_4.5/20%Super P@15%Li₇P₃S₁₁ cathode exhibit high reversible capacity and excellent cycling stability, delivering an initial discharge capacity of 975.7 mA h g⁻¹ at a current density of 0.1 A g⁻¹ and a reversible capacity of 464.8 mA h g⁻¹ after 2500 cycles at 0.5 A g⁻¹. These results demonstrated that the a-NbS_4.5/20%Super P@15%Li₇P₃S₁₁ nanocomposite is a promising potential cathode for all-solid-state batteries.