Steel slag is a by-product of the steel industry and usually contains a high amount of f-CaO and f-MgO, which will result in serious soundness problems once used as a binding material and/or aggregates. To relieve this negative effect, carbonation treatment was believed to be one of the available and reliable methods. By carbonation treatment of steel slag, the phases of f-CaO and f-MgO can be effectively transformed into CaCO₃ and MgCO₃, respectively. This will not only reduce the expansive risk of steel slag to improve the utilization of steel slag further but also capture and store CO₂ due to the mineralization process to reduce carbon emissions. In this study, based on the physical and chemical properties of steel slag, the carbonation mechanism, factors affecting the carbonation process, and the application of carbonated steel slag were reviewed. Eventually, the research challenge was also discussed.

Lithium metal batteries (LMBs) show great promise for achieving energy densities over 400 Wh·kg⁻¹. However, highly flammable organic electrolytes are a long-lasting problem that triggers safety hazards and hinders the commercial application of LMBs. Here, a nonflammable diluted highly concentrated electrolyte (DHCE) with ethoxy(pentafluoro)cyclotriphosphazene (PFPN) as a diluent is developed to simultaneously achieve high safety and cycling stability of high-voltage LMBs. The optimal DHCE not only ensures reversible Li deposition/dissolution behavior with a superior average Coulombic efficiency (CE) over 99.1% on lithium metal anode (LMA), but also suppresses side reactions and stress crack on the LiCoO₂ (LCO) under high cut-off voltage. The newly developed DHCE exhibits high thermal stability, showing complete nonflammability and reduced heat generation between the electrolyte and delithiated LCO/cycled LMA. This work offers an opportunity for rational designing nonflammable electrolytes toward high-voltage and safe LMBs.