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Figure 3 Maxell sells rechargeable lithium-manganese-dioxideML-series rechargeable batteries. The company offers thesebatteries only to equipment manufacturers as built-in parts, notdirectly to end users.Another advancement in the technology of supercapacitorsis the emergence of lithium-ion supercapacitors. For example,JM Energy two years ago announced its first lithiumionsupercapacitors, the 1000F/2000F series. The devices remainin limited production, however. In December 2010, supercapacitor-manufacturerIoxus announced its lithium-ionseries with an energy density 115% higher than that of standardelectric double-layer capacitors.Ioxus last year received a federal grant to work with BinghamtonUniversity (www.binghamton.edu) on increasing energydensity in supercapacitors. The company’s resulting workyielded a “hybrid” capacitor, which comes in 220, 300, 800,and 1000F versions. It uses a positive carbon electrode anda negative lithium-ion electrode and has a 20,000-cycle lifetimecompared with approximately 1000 cycles for a battery.Leakage current is 0.6 mA at 72 hours. The devices’ heightand diameter measurements, respectively, range from 45×22mm for the 220F version to 88×35 mm for the 1000F version.Prices for the 300F version range from $4 to $6 each.EDNREFERENCES1Conner, Margery, “Run for your life: ultralow-power systemsdesigned for the long haul,” EDN, May 26, 2005, pg 46,http://bit.ly/f6q6rP.2Odland, Keith, “Selecting the best battery for embeddedsystemapplications,” EDN, Nov 18, 2010, pg 36, http://bit.ly/evzniq.3Conner, Margery, “Energy-harvesting conference coversboth cutting-edge and established technologies,” EDN, June13, 2007, http://bit.ly/gCHicK.4Conner, Margery, “Energy harvesters extract power fromlight, vibrations,” EDN, Oct 27, 2005, pg 45, http://bit.ly/hx8Xqw.You can reachTechnical EditorMargery Connerat 1-805-461-8242 andmargery.conner@ubm.com.