Mechanism Behind Capacitor’s High-Speed Energy Storage Disco
Enviado: 26 fev 2012, 10:57
Mechanism Behind Capacitor’s High-Speed Energy Storage Discovered
" Researchers at North Carolina State Universityhave discovered themeans bywhich a polymer known as PVDF enables capacitors to storeand release largeamounts of energy quickly. Their findings could lead to much more powerful and efficient electriccars.
Capacitorsare like batteries in thattheystoreand release energy. However, capacitors useseparated electrical charges, rather than chemical reactions, to store energy. The charged particles enable energyto be stored and released veryquickly. Imagine an electric vehicle that can accelerate from zero to 60 miles per hour at the same rate as a gasoline-powered sports car. There are no batteriesthatcan power that type ofacceleration becausethey releasetheir energy too slowly. Capacitors, however,could be up to the job – if theycontained the right materials.
NCState physicist Dr. Vivek Ranjan had previously found that capacitors which contained thepolymer polyvinylidene fluoride,or PVDF,in combination with another polymer called CTFE, were ableto store up to seven timesmore energy than those currentlyin use.
“We knew that this material makesan efficientcapacitor, but wanted to understand the mechanism behind itsstorage capabilities,” Ranjan says.
In research published in Physical Review Letters, Ranjan, fellow NC Statephysicist Dr. JerzyBernholc and Dr. Marco Buongiorno-Nardelli from the University of North Texas, did computer simulations to seehow theatomic structure within the polymer changed when an electricfield was applied. Applying an electric field to thepolymer causes atoms within it to polarize,which enables thecapacitor to store and release energy quickly. Theyfound that when an electrical field wasapplied to the PVDF mixture,the atoms performed a synchronized dance,flipping from anon-polar to a polar state simultaneously, and requiring a very small electrical charge to do so.
“Usuallywhen materials change from a polar to non-polar state it’s a chain reaction – starting in one placeand then moving outward,” Ranjan explains. “In terms of creating an efficient capacitor,this type ofmovementdoesn’t workwell – itrequiresa largeamountof energyto getthe atoms to switch phases, and you don’t get out much moreenergythan you put into the system.
“In the case of thePVDF mixture,the atoms change their state all at once,which meansthatyou get a large amount of energy out of the system at very little cost in terms ofwhat you need to putinto it. Hopefully these findingswill bring us even closer to developing capacitors that will give electric vehicles thesameacceleration capabilities as gasoline engines.”
Em: http://news.ncsu.edu/releases/ranjanprl/
" Researchers at North Carolina State Universityhave discovered themeans bywhich a polymer known as PVDF enables capacitors to storeand release largeamounts of energy quickly. Their findings could lead to much more powerful and efficient electriccars.
Capacitorsare like batteries in thattheystoreand release energy. However, capacitors useseparated electrical charges, rather than chemical reactions, to store energy. The charged particles enable energyto be stored and released veryquickly. Imagine an electric vehicle that can accelerate from zero to 60 miles per hour at the same rate as a gasoline-powered sports car. There are no batteriesthatcan power that type ofacceleration becausethey releasetheir energy too slowly. Capacitors, however,could be up to the job – if theycontained the right materials.
NCState physicist Dr. Vivek Ranjan had previously found that capacitors which contained thepolymer polyvinylidene fluoride,or PVDF,in combination with another polymer called CTFE, were ableto store up to seven timesmore energy than those currentlyin use.
“We knew that this material makesan efficientcapacitor, but wanted to understand the mechanism behind itsstorage capabilities,” Ranjan says.
In research published in Physical Review Letters, Ranjan, fellow NC Statephysicist Dr. JerzyBernholc and Dr. Marco Buongiorno-Nardelli from the University of North Texas, did computer simulations to seehow theatomic structure within the polymer changed when an electricfield was applied. Applying an electric field to thepolymer causes atoms within it to polarize,which enables thecapacitor to store and release energy quickly. Theyfound that when an electrical field wasapplied to the PVDF mixture,the atoms performed a synchronized dance,flipping from anon-polar to a polar state simultaneously, and requiring a very small electrical charge to do so.
“Usuallywhen materials change from a polar to non-polar state it’s a chain reaction – starting in one placeand then moving outward,” Ranjan explains. “In terms of creating an efficient capacitor,this type ofmovementdoesn’t workwell – itrequiresa largeamountof energyto getthe atoms to switch phases, and you don’t get out much moreenergythan you put into the system.
“In the case of thePVDF mixture,the atoms change their state all at once,which meansthatyou get a large amount of energy out of the system at very little cost in terms ofwhat you need to putinto it. Hopefully these findingswill bring us even closer to developing capacitors that will give electric vehicles thesameacceleration capabilities as gasoline engines.”
Em: http://news.ncsu.edu/releases/ranjanprl/
