High-performance Li4SiO4 sorbents prepared from solid waste for CO2 capture

Li 4 SiO 4 shows great promise for cyclic high-temperature CO 2 capture due to its excellent stability, high capacity, and low regeneration temperature. However, the practical application of Li 4 SiO 4 is mainly limited by the high cost of raw materials, particularly lithium resources. Additionally, the heavy use of lithium-ion batteries (LIBs) in developing renewable energy sources raises concerns about the disposal of many waste LIBs. This article synthesized Li 4 SiO 4 sorbent (BR-Li 4 SiO 4 ) using spent lithium cobalt oxide (LiCoO 2 ) cathodes and rice husk ash for CO 2 capture. Meanwhile, we also prepared R-Li 4 SiO 4 /P-Li 4 SiO 4 using commercial Li 2 CO 3 and rice husk ash/commercial crystalline SiO 2 as a comparison. The results show that the BR-Li 4 SiO 4 sorbent exhibited excellent CO 2 capture capacity and cycling stability at 675 °C, maintaining a stable capacity of 0.28 g/g under 100% CO 2 after 30 cycles. BR-Li 4 SiO 4 also demonstrated significantly reduced costs and a superior microstructure compared to R-Li 4 SiO 4 and P-Li 4 SiO 4 . Furthermore, the impact of a simulated flue gas containing 15% CO 2 and 10% H 2 O on Li 4 SiO 4 adsorption was investigated. It was found that the adsorption of CO 2 was decreased at low CO 2 concentrations, but the addition of 10% H 2 O showed a slight enhancement in CO 2 adsorption. Under a mixture of 15% CO 2  + 10% H 2 O (balanced with N 2 ), the maximum adsorption capacity of BR-Li 4 SiO 4 was 0.17 g/g, and its optimal adsorption temperature decreased by 50 °C to 625 °C compared to 15% CO 2 . Therefore, this study will provide valuable insights into the industrial application of Li 4 SiO 4 in CO 2 adsorption.