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Lithium‐ion batteries with their portability, high energy density, and reusability are frequently used in today's world. Under extreme conditions, lithium‐ion batteries leak, burn, and even explode. Therefore, improving the safety of lithium‐ion batteries has become a focus of attention. Researchers believe using a solid electrolyte instead of a liquid one can solve the lithium battery safety issue. Due to the low price, good processability and high safety of the solid polymer electrolytes, increasing attention have been paid to them. However, polymer electrolytes can also decompose and burn under extreme conditions. Moreover, lithium dendrites are formed continuously due to the uneven charge distribution on the surface of the lithium metal anode. A short circuit caused by a lithium dendrite can cause the battery to thermal runaway. As a result, the safety of polymer solid‐state batteries remains a challenge. In this review, the thermal runaway mechanism of the batteries is summarized, and the batteries abuse test standard is introduced. In addition, the recent works on the high‐safety polymer electrolytes and the solution strategies of lithium anode problems in polymer batteries are reviewed. Finally, the development direction of safe polymer solid lithium batteries is prospected. [ABSTRACT FROM AUTHOR]

Lithium metal batteries (LMBs) attract considerable attention for their incomparable energy density. However, safety issues caused by uncontrollable lithium dendrites and highly flammable electrolyte limit large‐scale LMBs applications. Herein, a low‐cost, thermally stable, and low environmentally‐sensitive lithium nitrate (LiNO3) is proposed as the only lithium salt to incorporate with nonflammable triethyl phosphate and fluoroethylene carbonate (FEC) co‐solvent as the electrolyte anticipated to enhance the performance of LMBs. Benefiting from the presence of NO3− and FEC with strong solvation effect and easily reduced ability, a Li3N–LiF‐rich stable solid electrolyte interphase is constructed. Compared to commercial electrolytes, the proposed electrolyte has a high Coulombic efficiency of 98.31% in Li‐Cu test at 1 mA cm−2 of 1.0 mAh cm−2 with dendrite‐free morphology. Additionally, the electrolyte system shows high voltage stability and cathode electrolyte interphase film‐forming properties with stable cycling performances, which exhibit outstanding capacity retention rates of 96.39% and 83.74% after 1000 cycles for LFP//Li and NCM811//Li, respectively. Importantly, the non‐flammable electrolyte delays the onset of combustion in lithium metal soft pack batteries by 255 s and reduces the peak heat release by 21.02% under the continuous external high‐temperature heating condition. The novel electrolyte can contribute immensely to developing high‐electrochemical‐performance and high‐safety LMBs. [ABSTRACT FROM AUTHOR]

As a kind of bulk industrial solid waste, the massive accumulation of iron tailings has caused serious waste of resources and environmental pollution. In this study, a silane coupling agent (KH550) was used to modify the surface of iron tailings to produce MIT, and it was compounded with ammonium polyphosphate (APP) on thermoplastic polyurethane (TPU) to prepare a series of TPU/APP/MIT composites. Thermogravimetric (TG), cone calorimetric (CCT), thermogravimetric infrared, scanning electron microscopy, and Raman techniques were also used to analyze the combustion performance, smoke toxicity, and microscopic morphology. The TG test results showed that the compounding of APP and MIT significantly improved the residual carbon value of TPU composites at 700°C. CCT test results showed that the TPU/APP/MIT composites exhibited excellent flame retardancy and smoke suppression. Compared with pure TPU, PHRR, THR, and TSR of TPU/APP15/MIT10 composite decreased by 85.56%, 87.83%, and 86.17%, respectively, the peak release rates of CO and CO2 decreased by 69.26% and 90.34%, respectively. The above studies showed that APP and MIT have excellent flame retardant and smoke suppression effect on TPU materials, providing more opportunities for the study of TPU composites and metallurgical solid waste utilization. [ABSTRACT FROM AUTHOR]

A high content of flame retardant in non‐combustible electrolytes leads to deterioration of the electrochemical performance of lithium‐ion batteries (LIBs). Besides, fire hazard of most non‐flammable electrolytes is studied in coin cell, for which it is impossible to reveal real performance. Thus, the stable interfacial, phosphorus‐fixed nonflammable gel polymer electrolyte (GPE) with low content of flame retardant (7.5 wt.%) has been designed by in situ polymerization of tri(acryloyloxyethyl) phosphate and triethylene glycol dimethacrylate in electrolyte. After being heated by fire for >10 s, the GPE is still not ignited. The average capacity attenuation rate of graphite//GPE//Li (0.008%) is much lower than that of the liquid electrolyte (0.039%). Besides, the nonflammable GPE based pouch cell with good flexibility and excellent fire safety is prepared. No fire, no thermal runaway and no electrolyte leakage occur for 1 Ah flexible pouch cell with 100% SOC. The mechanism for high safety of pouch cell has also been revealed. First the amount of combustible pyrolysis products from thermal degradation of GPE is reduced through forming P and F containing char. Second, the combustion of GPE is extinguished through OH free radical quenching effect of flame retardant molecular. This work provides a guideline for designing high‐safety LIBs. [ABSTRACT FROM AUTHOR]

Iron tailings (IT) is the remaining industrial solid waste after beneficiation. The accumulation of billion tons of tailings not only occupies valuable land resources but also causes serious environmental pollution and human harm. This work aims to explore the potential application of IT in flame retardant field. The modified iron tailings (MIT) were combined with aluminum hypophosphite (AHP) to prepare a series of TPU/AHP/MIT composites by melt blending method. Thermogravimetric (TGA) test indicated that MIT and AHP significantly improved the thermal stability of the composites. The char residue of TPU/AHP22.5/MIT2.5 was enhanced to 29.60 wt% compared with 27.51 wt% of TPU/AHP25. Cone calorimetry test (CCT) confirmed that PHRR and THR of TPU/AHP15/MIT10 were decreased by 88.4% and 55.2% compared with those of pure TPU. Adding 2.5 wt% MIT could reduce the gas production of the TPU/AHP system by 32.82%. Scanning electron microscopy (SEM) and Raman spectroscopy tests confirmed that AHP/MIT system could increase the thickness and graphitization degree of char residue for the TPU composites, and thus increase the thermal stability and fire resistance of the composites. Lastly, the possible fire retarding mechanism of TPU/AHP/MIT composites was illustrated. This work provided a novel strategy for utilization of IT. [ABSTRACT FROM AUTHOR]

A novel and highly effective flame retardant (FR), DOPO‐TPMP oligomer, was synthesized by a simple condensation of 4‐(hydroxymethyl)‐2,6,7‐trioxa‐1‐phosphabicyclo[2.2.2]octane‐1‐oxide and phosphorus oxychloride followed by a polycondensation reaction with 6‐(2,5‐dihydroxyphenyl)‐6H‐dibenzo[c,e][1,2]oxaphosphinine‐6‐oxide. The chemical structure of DOPO‐TPMP was well characterized using Fourier transform infrared and NMR spectra. DOPO‐TPMP was used as an additive‐type FR for epoxy resin (EP). The FR properties of the resultant EP composites were investigated by limiting oxygen index (LOI) test, UL‐94 vertical burning test and cone calorimeter measurements. Specifically, the EP composite containing 10.0% DOPO‐TPMP achieved a LOI value of 36.1%, V‐0 rating in the UL‐94 test and a 58% reduction in peak heat release rate. Further mechanism analysis attributed the enhanced flame retardancy to the increased char yield on the addition of DOPO‐TPMP. © 2019 Society of Chemical Industry A novel oligomeric flame retardant, DOPO‐TPMP, was synthesized, which imparted high flame‐retardant performance to epoxy resins. [ABSTRACT FROM AUTHOR]

In this work, we reported the synthesis, characterization of Ce-doped titania nanotubes (Ce-TNTs), and application in flame retardancy of an intumescent flame-retardant polystyrene (PS/IFR) system. The flame retardancy of polystyrene (PS) composite that was composed of pentaerythritol, microencapsulated ammonium polyphosphate, and PS was enhanced significantly by adding a small amount (0.1 wt%) of (Ce-TNTs). The thermal properties of the flame-retardant PS were investigated by thermogravimetric analysis, limiting oxygen index (LOI), vertical burning test (UL-94), scanning electronic microscopy, dynamic mechanical thermal analysis, and the real-time Fourier transform infrared spectrometry (FTIR). The maximal decomposition rate temperature of PS/IFR containing Ce-TNTs in air is much higher than that of other PS composite without Ce-TNTs. The LOI value of PS/IFR that contained 0.1 wt% of Ce-TNTs was increased from 27.0 to 28.5, and the UL-94 rating was also enhanced to V-0 from no rating when the total loading of additive was the same. The real-time FTIR showed that the degradation process was changed after the addition of TNTs. All results indicated that Ce-TNTs had a significant synergistic effect on the flame retardancy of PS/IFR. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the effect of organo-modified montmorillonite (OMMT) on a novel intumescent flame retardant (IFR) system was studied in poly(1,4-butylene terephthalate) (PBT) composites containing microencapsulated ammonium polyphosphate (MAPP) and melamine cyanurate (MC). Nanocomposite morphology was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal decomposition analysis was studied via thermogravimetric analysis (TGA). Combustion behavior was investigated by microcombustion calorimeter (MCC), limited oxygen index (LOI), and UL-94 test. Residues obtained after samples treated in muffle furnace at 500°C under air condition for 10 min were analyzed through X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). It was found that the addition of OMMT improved the flame retardancy of PBT/IFR composites significantly. A mass of microcomposite structure particles formed in the heating or combustion process of PBT/IFR/OMMT nanocomposites were found for the first time in the SEM images, which is strong evidence to confirm the migration or accumulation of montmorillonite and carbonaceous-silicate materials during the heating or combustion process. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]