First Year Assessment de Abdumalik Yusuf titulado “Study of the influence of phosphorus based flame retardants on the flammability, thermal and electrochemical properties of gel polymer electrolytes” – En la Sala de Seminarios a las 12:00 hr

RESUMEN:

Today, almost every portable device is powered by a lithium ion battery. Despite the wide use of lithium ion batteries, they suffer from serious safety issues. Gel polymer electrolytes (GPEs) are one of the most promising candidates to solve safety issues such as fire and liquid electrolyte leakage in Lithium-ion batteries.  In this preliminary work, Polyacrylonitrile (PAN) was modified with a phosphorus containing flame retardant,9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) by mechanical blending, and flame retardant PAN-based nanofibrous membranes were synthesized successfully using the electrospinning technique. The fire behavior of the flame retardant PAN based membranes was studied using the Micro combustion calorimetry (MCC) and a decrease in the heat release rate of 47% was observed for PAN-20DOPO membrane with flame retardant loading of 16.7 wt.% compared to Pristine PAN membrane.

Afterwards, the flame retardant PAN-based nanofibrous membranes were utilized in combination with 1 M LiPF6 in Ethylene carbonate/Ethyl methyl carbonate liquid electrolytes as a gel polymer electrolyte in Lithium ion batteries. All the flame retardant PAN based GPEs showed a high ionic conductivity above 4 mS/cm at room temperature and an excellent electrochemical stability of up to 5.0 V (vs. Li+/Li).

Moreover. The LiFePO4/GPE/Li cells using flame retardant PAN-DOPO GPEs and an LiFePO4 cathode yielded relatively higher discharge capacities at

25 mA/g, 50 mA/g and 100 mA/g current densities compared to Pristine PAN. This is ascribed to the plasticization effect of the flame retardant which led to a higher ionic conductivity of PAN-DOPO nanofibers gel electrolytes.