Preparation Of Melamine Resin-basedelectrode Material And Application In Supercapacitor

Supercapacitor?SC?is a new type of clean energy storage device.It has the advantages of ultra-high specific capacity,high specific power,fast charging speed,long cycle life,superior low temperature performance,maintenance-free,safety and environmental protection.According to the difference in the energy storage mechanisms of?SC?,it can be divided into an electric double layer capacitor?EDLC?and a pseudo capacitor?PC?.?EDLC?uses high specific surface area material and electrostatic capacity formed between electrolyte/electrode interface to store energy.?PC?uses conductive polymer or metal oxide as electrode material.The active substances in the electrode produce reversible oxidation/reduction resulting in a higher specific capacity than that of?EDLC?.Melamine is rich in nitrogen,reacteing with aldehydes and to produce melamine-resin with excellent properties.After carbonization at high temperature,carbon material rich in nitrogen and oxygen is formed.There are two forms of double-layer capacitance and pseudo-capacitance in supercapacitor electrode materials,which have a wide range of prospects.The main contents of this paper are introduced as follows:A uniform and well-dispersed melamine formaldehyde resin-based microspheres have been synthesized at 60? by a facile one-step process at the presence of polyvinyl alcohol.Polyvinyl alcohol enters into the skeleton of copolymer main chain through reaction with formaldehyde.It not only acts as a dispersing agent,but also tailors the formation of melamine resin microspheres.After carbonization at 700?,the carbon microsheets with regular thickness are obtained in which the nitrogen content is up to12.4 at.%and oxygen content is 10.5 at.%.Both heteroatoms bring considerable pseudo-capacitance.The carbon-based electrode material exhibits high gravimetric capacitance with 270 F g^-1 at the current density of 0.5 A g^-1,performing ideal rate capability with 207 F g^-1 at the current density of 10 A g^-1.When the material is made into an energy storage device,,there is excellent cycling stability with 101%capacitive retention after 10000 cycles at the current density of 10 A g^-1.The copolymerization of melamine and thiourea in the presence of formaldehyde at the molar ratio of 1:8 in acidic condition resulted in the formation of copolymer resin with superior properties.The porous carbon material with rich hetero-atom content was prepared by carbonization at 750? at high temperature and the two resins were used as templates.The material not only retained the rich nitrogen content of melamine resin?up to 20.7 at.%?,but also introduced the sulfur element of thiourea formaldehyde resin.Used as carbon material for supercapacitor,the material owns high specific capacitance with 311 F g^-1 at the current density of 1 A g^-1 and ideal rate capability with 229 F g^-1at the current density of 10 A g^-1.After 10000 cycles at the current density of 10 A g^-1,there is excellent cycling stability with 103%capacitive retention that material has well electrochemical properties.Melamine reacted with formaldehyde in polyethylene glycol?PEG?solution of different molecular weight,and polyethylene glycol participated in the formation process of melamine resin,and PEG as porogen agent changed the morphology of melamine resin.After high temperature carbonization,the carbon material with special morphology was prepared which was analyzed by SEM and XRD.The carbon material was prepared into supercapacitor electrode material excellent performance.