Kinetics Study on CO 2 Adsorption of Li 4 SiO 4 Sorbents Prepared from Spent Lithium-Ion Batteries

With the advancement of global carbon reduction efforts and the rapid development of battery industries, the scale of spent lithium-ion batteries (LIBs) has increased dramatically. Extracting lithium from spent LIBs to synthesize Li 4 SiO 4 sorbents not only addresses the challenge of battery recycling but also reduces the production cost of CO 2 sorbents, making it a research hotspot. However, the CO 2 adsorption behavior of these sorbents under the effect of impurities may differ from the traditional Li 4 SiO 4 , and there is a lack of systematic research on the adsorption kinetics. To address this issue, two Li 4 SiO 4 sorbents are prepared from spent ternary LIBs, and their adsorption kinetics are comprehensively investigated using classical kinetic models. Results show that the reaction order of LSO and Na-LSO is 0.41 and 1.63, respectively, with activation energies of 72.93 kJ/mol and 99.23 kJ/mol in the initial kinetic-controlled stage, and 323.15 kJ/mol and 176.79 kJ/mol in the following diffusion-controlled stage. In the cyclic processes, loss-in-capacity is observed on LSO due to the simultaneous decrease in rate constants in both the kinetic and diffusion-controlled stages, while Na-LSO could almost maintain its capacity by having a much bigger rate constant during the kinetic-controlled stage. This study reveals the adsorption kinetics of Li 4 SiO 4 prepared from spent LIBs and could provide theoretical support for the targeted design of efficient and low-cost CO 2 sorbents.