fig2

Figure 2. (A) Separator coated with chitosan-modified Al₂O₃ nanoparticles for selective scavenging of Mn²⁺ and Ni²⁺; (A) are reprinted with permission from Ref^[156], Copyright © 2024 Wiley; (B) High-temperature-induced Diels-Alder reactions of electrolyte solvents form oligomers that block separator pores, reducing Li⁺ transport and triggering thermal shutdown; (B) are reprinted with permission from Ref^[160], Copyright © 2025 Wiley; (C) Al₂O₃/APP “sandwich” separator on polyethylene, sealed with phenolic resin; APP carbonization upon heating provides a protective barrier, improving battery safety; (C) are reprinted with permission from Ref^[170], Copyright © 2020 Wiley; (D) Silica microcapsules containing phase-change materials on the separator enable heat-triggered release of flame retardants, enhancing thermal safety; (D) are reprinted with permission from Ref^[54] ,Copyright © 2022 Elsevier. RT: Room temperature; VC-(DMFu)_m: Vinyl Carbamate-(2,5-Dimethylfuran)_m; APP: ammonium polyphosphate; PE: polyethylene; PPA: polyphenylenamine; PFR: polyfluorene resin; PCM: polymer composite membrane; TEP: triethyl phosphate.