A lithium-sulphur (Li–S) battery with a microporous carbon paper as a bifunctional interlayer is reported, which significantly improves the battery's capacity, cycle life, and charge rate. The microporous carbon paper, placed between the cathode and separator, enhances active material utilization and reduces internal charge transfer resistance. It also localizes soluble polysulphide species, preventing their shuttling between the anode and cathode, which leads to capacity fade. This design simplifies battery fabrication without requiring complex synthesis or surface modification. The carbon interlayer acts as both an "upper current collector" for the low-conductivity sulphur cathode and a "polysulphide stockroom" to retain cyclability. The battery shows high capacity retention (85%) and Coulombic efficiency (97.6%) after 100 cycles at 1C rate. At 2C rate, it maintains 846 mA h g⁻¹ after 150 cycles with an average Coulombic efficiency of >98%. The study highlights the potential of this simple configuration for commercial Li–S batteries, offering a cost-effective and practical solution for energy storage.A lithium-sulphur (Li–S) battery with a microporous carbon paper as a bifunctional interlayer is reported, which significantly improves the battery's capacity, cycle life, and charge rate. The microporous carbon paper, placed between the cathode and separator, enhances active material utilization and reduces internal charge transfer resistance. It also localizes soluble polysulphide species, preventing their shuttling between the anode and cathode, which leads to capacity fade. This design simplifies battery fabrication without requiring complex synthesis or surface modification. The carbon interlayer acts as both an "upper current collector" for the low-conductivity sulphur cathode and a "polysulphide stockroom" to retain cyclability. The battery shows high capacity retention (85%) and Coulombic efficiency (97.6%) after 100 cycles at 1C rate. At 2C rate, it maintains 846 mA h g⁻¹ after 150 cycles with an average Coulombic efficiency of >98%. The study highlights the potential of this simple configuration for commercial Li–S batteries, offering a cost-effective and practical solution for energy storage.