Anion-Doped Cobalt Selenide with Porous Architecture for High-Rate and Flexible Lithium–Sulfur Batteries

Emerging catalytic host for sulfur is an effective approach to breaking the limits of lithium–sulfur batteries for practical applications. Herein, the hydrangea-shaped Co_0.85Se electrocatalyst with macroporous architecture is synthesized. Besides, to improve the electronic conductivity of Co_0.85Se, some defects (S-doped) are introduced into the structure of crystals. The S-doped Co_0.85Se exhibited an outstanding electrocatalytic effect on lithium polysulfides conversion and can induce and regulate uniform growth of insoluble Li₂S on its surface due to the synergistic adsorption by Se and S. As a result, the S/C cathode achieved a high initial capacity of 1340.6 mAh g⁻¹ at 0.5 C and a stable cycling capacity of 666.6 mAh g⁻¹ at 1 C after 500 cycles by 5 wt% Co_0.85SeS additions. Moreover, high S loading cathodes are designed through in situ synthesis of Co_0.85SeS on flexible carbon cloth (Co_0.85SeS@CC). The porous and open framework of Co_0.85SeS@CC facilitated electrolyte infiltration and accommodated the volume change of sulfur during the charge/discharge process. Taking by these advantages, a high areal capacity of 9.663 mAh cm⁻² is achieved at a high sulfur loading of 9.98 mg cm⁻². Even at a high current density of 15 mA cm⁻², a reversible capacity of 603.7 mAh g⁻¹ is maintained at a sulfur loading of 6.52 mg cm⁻². This proposed work provides a feasible approach to high-rate and flexible Li–S batteries.