Organolithium-derived alkali-doped highly durable Li4SiO4 heat carrier for solar thermochemical energy storage

Abstract

Thermochemical energy storage (TCES) technology plays a vital role in utilizing solar energy to produce electricity. However, traditional TCES technologies such as calcium looping route suffer from unsatisfactory long-term durability. Lithium looping has demonstrated excellent cyclic stability, but it has been rarely employed for energy storage. In this work, organolithium-derived Li4SiO4 heat carrier was synthesized and further decorated with alkali doping. The porous microstructures and wrinkled surfaces of organolithium-derived Li4SiO4 were demonstrated, with alkali doping facilitating the formation of low-temperature eutectic materials and reducing CO2 diffusion resistance, thereby enhancing its cyclic energy storage performance. Li4SiO4 doped with 3 wt% K2CO3 shows energy storage density of as high as 638.23 kJ/kg, equal to a high conversion of 81.41% over long storage/release tests of 15 cycles. The high energy density and excellent cyclic durability of Li4SiO4 were attributed to its porous microstructures and formed eutectic melts. Furthermore, for practical application, the carbonation (or heat release) temperature for Li4SiO4 looping TCES system was optimized. To sum up, Li4SiO4 exhibits great potential as a candidate for thermochemical energy storage in solar energy utilization due to its excellent long-term cyclic durability.