Understanding the combustion behavior of electric bicycle batteries and unveiling its relationship with fire extinguishing

In this study,a detailed analysis of the combustion behaviors of the lithium iron phosphate(LFP)and lithium manganese oxide(LMO)batteries used in electric bicycles was conducted.This research included quantitative measurements of the combustion duration,flame height,combustion temperature,heat release rate,and total heat release.The results indicated that LMO batteries exhibited higher combustion temperatures of 600–700°C,flame heights of 70–75 cm,a significantly higher heat release rate of40.1 k W(12 Ah),and a total heat release of 1.04 MJ(12 Ah)compared to LFP batteries with the same capacity.Based on these experimental results,a normalized total heat release(NORTHR)parameter was proposed,demonstrating good universality for batteries with different capacities.Utilizing this parameter,quantitative calculations and optimization of the extinguishing agent dosage were conducted for fires involving these two types of batteries,and the method was validated by extinguishing fires for these two types of battery packs with water-based extinguishing fluids.

Combustion behavior and mechanism of molecular perovskite energetic material DAP-4-based composites with metal fuel Al

Combined with the oxidizer anions and fuel cations,molecular perovskite energetic materials show a good potential.In this work,the combustion behavior and mechanism of metal fuel aluminium(Al)with molecular perovskite energetic material(H_(2)dabco)[NH4(ClO_(4))_(3)](DAP-4)as a high-energy oxidant was investigated.The DAP-4 based composites with metal fuel Al were designed and fabricated by the different mass ratios.Results showed that DAP-4 exhibits a good oxygen-supplied capacity for enhancing the combustion performance of Al.The maximum combustion heat of DAP-4/Al-3 at the Al/O mass ratio of 38:62 is up to 10,412 J/g in the inert gas,which is higher than those of other ratios and the mixtures of other energetic materials and Al.The evolution of pressure output,pressurization rate,and flame temperature was monitored for DAP-4/Al with different mass ratios.Composites DAP-4/Al/F were characterized by burning rates.The combustion reaction mechanism of metal fuel Al with DAP-4 as a high-energy oxidant was provided.DAP-4 was ignited firstly and released acid and oxidizing gases,which corroded Al_(2)O_(3)shells on Al particle surfaces and accelerated the combustion reaction with Al to release a lot of energy.This work offered a new idea that molecular perovskite energetic materials have great potential in the high-energy Al-based solid rocket propellants.