NPRE 498 Energy Storage Electrochemical Supercapacitor AKA Electrical Double Layer Capacitor • Basic principle • Electrode materials • Electrolytes • Similar technology (Electrolytic capacitors)
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NPRE 498 Energy Storage
Electrochemical SupercapacitorAKA Electrical Double Layer Capacitor
• Basic principle • Electrode materials • Electrolytes• Similar technology (Electrolytic
capacitors)
NPRE 498 Energy Storage
• Electrical double layer Principles
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Schematic of a Supercapacitor
NPRE 498 Energy Storage
Cyclic Voltammetry
Cyclic voltammetry of supercapacitors:
NPRE 498 Energy Storage
The electrode materials Typically based on activated carbons 1.AC paste + rubber binder 2.AC cloths/fabrics/non-woven3.Carbon aerogel4.Other carbon nanoforms
(tubes/balls…)
Other materials with Redox boostfor example RuO2
NPRE 498 Energy Storage
AC: examples AC cloth
NPRE 498 Energy Storage
AC examples: aerogel
Aerogel of SiO2
Aerogel of CarbonSEM
How to make a C aerogel capacitor
NPRE 498 Energy Storage
Making of Carbon Aerogel• Starting material: Resorcinol + Formaldehyde (RF)• Resorcinol is like phenol• The process is like making phenol formaldehyde resin• Resorcinol formaldehyde is a wood glue
Resorcinol
Formaldehyde
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Making of Carbon AerogelThe sol-gel process
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The sol-gel process, big scale
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RF aerogel vs carbon aerogel
A resorcinol-formaldehyde polymer aerogel (left) and a carbon aerrogel (right)
Pyrolysis
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From RF to carbon aerogelPyrolysis after a CO2 supercritical drying
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PseudoUltracapacitorOften called Asymmetric Ultra(Super)-capacitor with RuO2 on one side to improve the specific energy
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PseudoUltracapacitor materials
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Electrolyte
Two types 1.Aqueous (Safe, limited to 1.4V) 2.Non-aqueous (Expensive, voltage up
to 3~4V, specific energy then can be 6 times more)
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Electrolyte
Chemical compositions 1.Aqueous (water solution of sulfuric
acid or potassium hydroxide) 2.Non-aqueous:
Solvent is typically a polycarbonate electrolyte conductor typically is
Et4NBF4 (Tetraethylammonium tetrafluoroborate)
NPRE 498 Energy Storage
Performance
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