Bio-inspired Nanoscaled Electronic/Ionic Conduction Networks for Room-Temperature All-Solid-State Sodium-Sulfur Battery

Abstract Sulfur cathode with nano-scaled electronic/ionic network is essential for all-solid-state Na/S batteries to achieve high energy density and long cycle life. However, it is great challenged to fabricate such a structure using either mechanical milling or liquid-phase reaction method. Here, a S-Na3SbS4-C cathode with distributed micro-scaled primary electronic/ionic highways along with nano-scaled secondary local-roads is fabricated by combining the liquid-phase reaction and mechanical milling. The formation mechanism for nano-scaled local-roads in S-Na3SbS4-C is systematically investigated. The S-Na3SbS4-C nanocomposite cathode with 3D distributed primary and secondary ionic/electronic conduction network provides a high initial discharge capacity of 1504.3 mAh g-1 at 50 mA g-1 with Coulombic efficiency of 98.5% at room temperature. Meanwhile, S-Na3SbS4-C/Na cells also demonstrate excellent rate capability with capacities of 1386.3, 1324.1, 1150.8, 893.4, 825.6, 771.2 and 662.3 mAh g-1 at current densities of 50, 100, 200, 300, 500, 1000 and 2000 mA g-1, respectively. Even at ultrahigh cathode loading of 6.34 and 12.74 mg cm-2, the S-Na3SbS4-C/Na cells can deliver reversible discharge specific capacities of 742.9 and 465.6 mAh g-1 at 100 mA g-1, respectively. S-Na3SbS4-C/Na cell represents one of the best rate performances for room-temperature all-solid-state sodium-sulfur batteries reported to date. This work provides a simple strategy to design mixed conductive composite cathode for high-performance room-temperature all-solid-state sodium-sulfur batteries.