Simplifying and Optimizing Li<sub>4</sub>SiO<sub>4</sub> Preparation from Spent LiFePO<sub>4</sub> Batteries with Enhanced CO<sub>2</sub> Adsorption
Jiaqi Ruan, Yichao Tong, Jingyu Ran, Changlei Qin
Abstract
A large amount of spent lithium batteries, especially lithium iron phosphate (LiFePO 4 ), is discarded due to their limited lifespan and poses a great threat to the environment. At the same time, the potential application of Li 4 SiO 4, an efficient high-temperature CO 2 sorbent, is largely limited by the high cost of lithium resources. Thus, the preparation of Li 4 SiO 4 from spent LiFePO 4 batteries has great potential for achieving waste recycling and reducing CO 2 capture costs. However, the process of recycling spent LiFePO 4 batteries to synthesize Li 4 SiO 4 sorbents still needs to be well investigated. This work proposes to simplify the preparation scheme by combing precipitation, Na doping, and synthesis processes and further optimizing the key variables of pH, Na 2 CO 3 ratio, and heating rate. An optimal condition is determined to be pH = 9, Na 2 CO 3 ratio = 11 wt %, and heating rate = 5 °C/min, and the sorbent prepared shows a superior stable CO 2 capacity of 0.24 g/g in 80 adsorption/desorption cycles. The work develops an effective Li 4 SiO 4 preparation scheme from spent LiFePO 4 batteries with largely enhanced CO 2 adsorption performance and reduced cost and could achieve a win–win situation in waste recycling and CO 2 mitigation.