Efficient SrO-based thermochemical energy storage using a closed-loop pressure swing

•SrO-based samples were tested for energy storage using a pressure swing approach.•Calcination at low CO2 pressure allowed performing the cycles at 900 °C.•The sintering-induced deactivation of SrO was reduced with the addition of additives.•The highest conversion values were obtained when ZrO2 and MgO were used as additives.•SrO-based composites outperform natural carbonates in thermal-to-electric performance.