5V-class sulfurized spinel cathode stable in sulfide all-solid-state batteries

Abstract

Sulfide all-solid-state lithium-ion batteries represent one of the most promising energy storage technologies duo to higher safety and ionic conductivities. To further improve its energy density and application, high-voltage LiNi0.5Mn1.5O4 (LNMO) spinel cathode is highly desirable due to its high energy density, low cost, environmental friendliness and Co-free nature. However, sulfide solid electrolyte is not compatible with LNMO cathode, for which issue the reported solutions majorly focus on surface coating. In this work, we propose an efficient approach to sulfurize LNMO itself for an essentially new LNMOS cathode, which not only suppresses interfacial side-reactions but also improve ionic/electronic conductivity of the cathode. This method ultimately improves the interfacial compatibility and consequently the LNMOS/sulfide all-solid-state-battery performances, including 3 times higher initial discharge capacity and much better reversible cycling stability. Detailed analyses on the interface are performed for in-depth understanding and further development of high-energy-density sulfide all-solid-state batteries using 5V-class spinel cathodes.