Conductivity enhancement of polyacrylonitrile-based electrolytes by addition of cascade nitrile compounds

A cascade nitrile compound ([CH2N(CH2CH2CN)(2)](2), ED4CN) made by addition of acrylonitrile to alkyldiamine (1,2-diaminoethane), has been used as a p lasticizer for solid polymer electrolytes. The ionic conductivity of a poly mer electrolyte using this type of plasticizer in polyethylene oxide (PEG)- and polyacrylonitrile (PAN)-LIClO4 complex was measured. Addition of ED4CN to PEG-based electrolytes did not enhance the conductivity of them. Howeve r, interaction between ED4CN and lithium ions in the complex was confirmed by infrared spectroscopy. The peak assigned to the stretching vibration of nitrile group in ED4CN shifted to high-energy side. The shift indicated tha t the nitrile groups interacted with the lithium ions in the PEG-based elec trolytes. Conductivity enhancement was observed in the PAN-based electrolyt es containing ED4CN. Conductivity of the electrolyte containing ED4CN was a bout 10 or 23 times larger than that of the electrolyte without ED4CN. Addi tion of ED4CN to a PAN-LiClO4 electrolyte decreases the glass transition te mperature of the complexes. Conductivity enhancement of the PAN-based elect rolyte with ED4CN containing lithium salt in high concentration was also co nfirmed. Other low molecular weight additives, tetraethylsulfamide (TESA) a nd a cascade nitrile compound. ([CH2CH2N(CH2CH2CN)(2)](2), TE4CN) were also used and their possibility for a conducting enhancer of PAN-based electrol ytes was tested. TESA was effective; however, TE4CN was inactive for a cond uctance enhancer of the PAN-based electrolytes. (C) 2000 Elsevier Science S .A. All rights reserved.