Impact of binder concentration and pressure on performance of symmetric CNFs based supercapacitors

• Published in: Electrochimica acta 2017-08, Vol.245, p.531-538
• Main Authors: Daraghmeh, Allan, Hussain, Shahzad, Servera, Llorenç, Xuriguera, Elena, Cornet, Albert, Cirera, Albert
• Format: Article
• Language: English
• Subjects: Aqueous electrolytes; BET; Capacitance; Carbon fibers; Carbon nanofibers; Electrodes; Flux density; Morphology; Nanofibers; Pore size; Pore size distribution; Porosity; Pressure; PVDF concentration; Scanning electron microscopy; SEM; Studies; Supercapacitors; Surface area; Symmetry
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2017.05.186

•The CNFs based supercapacitor performance is dependent on electrode preparation method.•The BET surface area and pore volume decrease with increase in PVDF concentration.•The specific capacitance increase with decrease in PVDF content.•The specific capacitance increase from with increase in pressure.•The high specific capacitance is related to moderate PVDF concentration and pressure. This paper discussed in details the impact of binder polyvynilidene fluoride (PVDF) concentrations (5, 10 and 20wt%) and pressures (∼382∼891∼1783 and ∼2547MPa) for the fabrication of electrodes based on Carbon nanofibers (CNFs) for supercapcitors. The surface area, pore size distribution and morphology were characterized by Brunauer–Emmett–Teller (BET) method and SEM. The decrease in specific surface area was about 31% and pore volume 14.6% with increase in PVDF concentration from 5 to 20wt% at ∼891MPa pressure. The assembled electrodes were tested with two electrode system in aqueous electrolyte. The specific capacitance was 80F/g for lowest concentration of PVDF (5wt%) and decreased about 28.3% with increase concentrations at same pressure ∼891MPa. In comparing the effect of pressure on specific capacitance, it increases about 38% for (PVDF, 10wt%; pressure ∼1783MPa) from (PVDF, 10wt%; pressure ∼891MPa); their corresponding power density 24502W/kg at energy density of 6.8Wh/Kg and 19886W/kg at energy density energy of 3.8 Wh/kg. ESR values increase from 0.3 to 1.9Ω with increase in PVDF concentration and decrease again to 0.5Ω with increase in pressure. The results show optimal conditions are 10wt% of PVDF and higher pressure of ∼891MPa.