A Compact Process to Prepare Silicon-Carbon Anode Material from Blast-Furnace Slag

The high silicon content of blast-furnace slag(BFS) makes it a secondary energy material. A method of extracting silicon from BFS is reported in this paper. NaOH solution is used to selectively extract SiO2 and Al2O3 from BFS. The effects of NaOH solution concentration, leaching time and leaching temperature on the leaching behavior of SiO2 from BFS are studied. Within a certain concentration range, the higher the concentration of NaOH, the easier the leaching. With the volume concentration of NaOH solution is 380 g/L, the leaching time is 50 min, and the leaching temperature is 90 °C, the leaching rate of Si is 63%, and the leaching rate of Si can be increased to 93% by secondary leaching. The leaching process of BFS is controlled by internal diffusion, and the calculated activation energy is 29.82 kJ/mol. The extracted Si is combined with PAN to prepare BFSi@PAN anode material. BFSi@PAN at a current density of 0.5 A/g, the initial charging capacity is 1367.36 mAh/g, the capacity is 1035.64 mAh/g after 100 cycles. Compared with industrial Si materials, it has excellent cyclic performance. The use of BFS in lithium-ion battery anode materials not only treats solid waste but also makes BFS high value-added utilization.