Heat resistant microporous membranes based on soluble poly(aryl ether ketone) copolymers for lithium ion battery separator

Abstract

To improve the safety and electrochemical properties of lithium ion batterie (LIB), a series of novel organic soluble poly(aryl ether ketone) (PAEK) copolymers were synthesized and used to fabricate LIB separators. The PAEK copolymers exhibited superior structural thermal stability and flame retardant, with glass transition temperature (Tg) above 150°C, oxygen index above 30 and no thermal decomposition before 500°C. Accordingly, the fabricated separators exhibited superior dimensional stability. The mechanical properties and electrolyte uptakes of the separators, as well as the electrochemical properties of the cells assembled with the separators were affected by the morphology and porosity of the separators. The separators with sponge‐like structure exhibited less electrolyte uptakes but better mechanical properties than that of the ones with finger‐like structure. The cell with finger‐like structure separator exhibited poorer electrochemical properties than sponge‐like structure separator, which might be caused by the collapse of some finger hole during the assemble process due to its poor mechanical properties. The charge–discharge performances of the cells after treated at 150°C demonstrates that the PAEK separators could be promising candidates for high‐safety LIB.

Synthesis and Characterization of a Self-Polycondensation Diazaphthalanone Monomer and Its Polymers from Polycondensation Reactions

“…The introduction of nitrogen heterocyclic diazoketone groups increases the free volume of macromolecular chains, reduces the interaction between chains, improves the thermal decomposition temperature, and makes the terpolymer have good heat resistance. This is related to the high decomposition temperature of the soluble PAEK copolymer synthesized by Zhihui Huang et al through the nucleophilic substitution copolymerization reaction of DFBP, DFA, and BPAF [30]. Therefore, high-temperature-resistant poly(aryl ether ketone) containing nitrogen heterocyclic diazoketone group structure can be synthesized by monomer structure design and ternary copolymerization, which pro- The TGA curve of monomer CDD, BHPF, and DFBP ternary copolymer PBCD shows that the thermal decomposition temperature T d−5% of 5 wt % of the polymer is 548 • C, which is slightly lower than that of binary copolymer PBD, and the carbon residue rate is 70% at 800 • C, indicating that the copolymer has good thermal properties.…”

A Critical Review on Materials and Fabrications of Thermally Stable Separators for Lithium‐Ion Batteries

“…Therefore, new efforts have been devoted to developing novel polymer separators with enhanced thermal properties based on high heat-resistant polymer materials. [26,60,[133][134][135][136][137][138] Widely used high-heat-resistant polymers include PVDF copolymer (melting point 170 °C (PVDF)), [139] PI (melting point >350 °C), [140] PAN (melting point ∼300 °C), [141][142][143][144] poly(ethylene terephthalate) (PET) (melting point > 250 °C), [145,146] poly(m-phenylene isophthalamide) (PMIA) (decomposition temperature ∼400 °C), [62] PEEK (decomposition temperature ∼530 °C), [147] poly (phthalazine ether sulfone ketone) (PPESK) (glass transition temperature 263-305 °C), [148,149] poly(arylene ether ketone) (PAEK) (decomposition temperature ∼500 °C), [150,151] polysulfonamide (PSA) (decomposition temperature ∼ 400 °C), [152] PVA (melting point 275-280 °C), [55] and cellulose-based polymers (melting point >250 °C). [153,154] To synthesize the novel polymer separators with enhanced thermal stability, techniques including electrospinning, [155] phase inversion, [156] and phase separation [55,157] have been developed and studied.…”