| abstract |
An ultracapacitor that comprises a first and second electrochemical cell that are connected in parallel is provided. The cells are define by a first electrode that contains a current collector having opposing sides coated with a carbonaceous material, a second electrode that contains a current collector having opposing sides coated with a carbonaceous material, and a separator positioned between the first electrode and the second electrode. The second cell is by the second electrode, a third electrode that contains a current collector having opposing sides coated with a carbonaceous material, and a separator positioned between the second electrode and the third electrode. The ultracapacitor also contains a nonaqueous electrolyte that is in ionic contact with the electrodes and contains a nonaqueous solvent and an ionic liquid. A package encloses the first cell, the second cell, and the nonaqueous electrolyte. |