Fig. 4: Electrochemical characterization of sulfur-carbon (S-C) composite positive electrodes (1 C = 1675 mA g_S⁻¹, testing temperature: 25 °C).

a Rate capability and b galvanostatic charge-discharge cycling at 0.2 C for the room temperature (RT)-pressed and 80 °C-pressed, and slurry-cast S-C composite positive electrodes (areal sulfur loading: 3 mg_S cm⁻²). Voltage profiles of c RT-pressed, d 80 °C-pressed, and e slurry-cast electrodes at various C-rate. Cyclic voltammetry (CV) curves of the f RT-pressed, g 80 °C-pressed h slurry-cast electrodes (areal sulfur loading: 3 mg_S cm⁻²). Nyquist plots of i RT-pressed, j 80 °C-pressed, and k slurry-cast electrodes measured at the fully charged state before and after 30 cycles, with l) the corresponding equivalent circuit model (areal sulfur loading: 3 mg_S cm⁻², (CPE, constant phase element; R_s, solution/electrolyte resistance; R_f, film resistance; R_ct, charge-transfer resistance; W_o, finite-length Warburg element). m Galvanostatic cycling at 1.0 C for the RT- and 80 °C-pressed, and slurry-cast electrodes (areal sulfur loading: 1 mg_S cm⁻²).