the solution of n , n - dimethyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium tetrafluoroborate ( dmdaco ) 2 + ( bf 4 − ) 2 in γ - butyrolactone ; the solution of n , n - diethyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium tetrafluoroborate ( dedaco ) 2 + ( bf 4 − ) 2 in acetonitrile ; the solution of n , n - diethyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium tetrafluoroborate ( dedaco ) 2 + ( bf 4 − ) 2 in γ - butyrolactone ; the solution of n , n - diethyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium tetrafluoroborate ( dedaco ) 2 + ( bf 4 − ) 2 in propylene carbonate ; the solution of n , n - diethyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium tetrafluoroborate ( dedaco ) 2 + ( bf 4 − ) 2 in the mixture of propylene carbonate ( 75 % vol ) and diglyme ( 25 % vol ); the solution of n , n - diethyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium tetrafluoroborate ( dedaco ) 2 + ( bf 4 − ) 2 in the mixture of γ - butyrolactone ( 75 % vol ) and methyl ethyl ketone ( 25 % vol ); the solution of n , n - dibutyl - 1 , 4 - diazabicyclo [ 2 . 2 . 2 ] octanediium hexafluorophosphate ( dbdaco ) 2 + ( bf 6 − ) 2 in acetonitrile . according to a further aspect of the invention there is provided an electrolyte for an edlc containing at least one dadaco tetrafluoroborate or hexafluorophosphate of the general formula ( 2 ) as defined above dissolved in an aprotic polar solvent or , preferably , a mixture of such solvents . the invention also comprises , as an additional aspect thereof , the use of a dadaco tetrafluoroborate or hexafluorophosphate of the general formula ( 2 ) as defined above dissolved in an aprotic polar solvent or a mixture of such solvents as an electrolyte for an electrochemical double layer capacitor . the electrolyte according to the invention may contain one single compound of formula ( 2 ) as defined above or , preferably , a mixture of two or more such compounds . however , the electrolyte according to the invention preferably contains a compound of formula ( 2 ) in combination with tetraethylammonium ( tea ) tetrafluoroborate , which is a well - known compound to be used in edlcs . in addition to the at least one compound of formula ( 2 ) the electrolyte according to the invention includes an aprotic polar solvent or a mixture of such solvents . preferably said aprotic polar solvent or solvents is / are at least one member selected from the group consisting of acetonitrile , propionitrile , 3 - methoxypropionitrile , γ - butyrolactone , γ - valerolactone , ethylene carbonate , propylene carbonate , n , n - dimethylformamide , 1 - methyl - 2 - pyrrolidinone , dimethoxyethane , 2 - methoxyethyl ether ( diglyme ) and tetrahydrofurane . the electrolyte usually contains the compound or compounds of formula ( 2 ) in a concentration from 0 . 5 mol / l up to the solubility limit which is about 2 . 0 mol / l at room temperature , preferably 0 . 7 to 1 . 5 mol / l and more preferably 0 . 8 - 1 . 3 mol / l . when using a compound of formula ( 2 ) in combination with tea tetrafluoroborate the sum of the concentrations of the two compounds is preferably within the range of 0 . 8 - 1 . 8 mol / l , more preferably about 1 . 0 to 1 . 2 mol / l , the fraction of the tea salt being within the range of 0 . 2 - 0 . 7 . electrochemical double - layer capacitors based on new electrolytes , which include the salts formed by doubly charged three - dimensional dadaco cations and tetrafluoroborate or hexafluorophosphate anions and dissolved in aprotic polar solvents as is disclosed in the present invention , can be used as back - up memory protection in personal computers , as pulse power sources for electric vehicle or spot welding applications , for load levelling the battery in hybrid power supplies of various types , etc . the invention will now be further illustrated by means of a number of non - limiting examples . weighed samples of ( dedaco ) 2 + ( bf 4 − ) 2 corresponding to concentrations of 0 . 5 , 0 . 75 , 1 . 0 , 1 . 25 and 1 . 5 mol / l were dissolved in 10 ml of acetonitrile , γ - butyrolactone or propylene carbonate , and the conductivity of the electrolytes obtained was measured at 25 ° c .— see the results in fig1 . weighed samples of ( dedaco ) 2 + ( bf 4 − ) 2 corresponding to the concentration of 1 . 0 mol / l were dissolved in 10 ml of acetonitrile , γ - butyrolactone or propylene carbonate , and the conductivity of the electrolytes obtained was measured at different temperature within the range of from 30 ° c . down to − 30 or − 40 ° c . the results are presented in fig2 . a weighed sample of ( dedaco ) 2 + ( bf 4 − ) 2 corresponding to the concentration of 1 . 0 mol / l was dissolved in 10 ml of a mixture comprising γ - butyrolactone ( 75 % vol ) and diglyme ( 25 %). the conductivity of the electrolyte obtained was measured at 25 ° c . the result is presented in table 1 . a weighed sample of ( dedaco ) 2 + ( bf 4 − ) 2 corresponding to the concentration of 1 . 0 mol / l was dissolved in 10 ml of a mixture comprising propylene carbonate ( 75 % vol ) and diglyme ( 25 % vol ). the conductivity of the electrolyte obtained was measured at 25 ° c . the result is presented in table 1 . a weighed sample of ( dbdaco ) 2 − ( pf 6 − ) 2 corresponding to the concentration of 1 . 0 mol / l was dissolved in 10 ml of acetonitrile , and the conductivity of the electrolyte obtained was measured at 25 ° c . the result is presented in table 1 . a weighed sample of ( dmdaco ) 2 − ( bf 4 − ) 2 corresponding to the concentration of 0 . 5 mol / l was dissolved in 10 ml of γ - butyrolactone , and the conductivity of the electrolyte obtained was measured at 25 ° c . the result is presented in table 1 . the electrolytes prepared according to examples 1 to 6 were then tested for their conductivity at different concentration or different temperature , the conductivity being measured in a temperature - controlled cell using the ok 102 / 1 conductivity meter ( produced by radelkis , hungary ). the results of the measurements are plotted in the enclosed fig1 and 2 as well as in table 1 , wherein as seen from fig1 and table 1 , the electrolytes proposed in the present invention demonstrate a fairly high conductivity , which smoothly depends on temperature in various solvents . an edlc mockup was assembled under an argon atmosphere , which included two collector electrodes made of aluminium and two working electrodes of 17 . 7 mm in diameter made of activated carbon cloth and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising 1 m ( dedaco ) 2 + ( bf 4 −) 2 in acetonitrile . then the mockup was cycled within the range of 1 . 7 - 3 . 5 v under constant current conditions ( 3 or 10 ma ), and its capacitance and inner resistance values were determined at room temperature from the charging / discharge curves . the results are presented in table 2 . an edlc mockup was assembled under an argon atmosphere , which included two collector electrodes made of aluminium and two working electrodes of 17 . 7 mm in diameter made of activated carbon cloth and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising a mixture of 0 . 7 m ( dedaco ) 2 + ( bf 4 − ) 2 and 0 . 5 m tea − bf 4 − in acetonitrile . then the mockup was cycled within the range of 1 . 7 - 3 . 2 v under constant current conditions ( 3 or 10 ma ), and its capacitance and inner resistance values were determined at room temperature from the charging / discharge curves . the results are presented in table 2 . an edlc mockup was assembled under an argon atmosphere , which included two collector electrodes made of aluminium and two working electrodes of 17 . 7 mm in diameter made of activated carbon cloth and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising a mixture of 0 . 3 m ( dedaco ) 2 − ( bf 4 ) 2 and 0 . 7 m tea − bf 4 − in acetonitrile . then the mockup was cycled within the range of 1 . 7 - 3 . 2 h under constant current conditions ( 3 or 10 ma ), and its capacitance and inner resistance values were determined at room temperature from the charging / discharge curves . the results are presented in table 2 . an edlc mockup was assembled under an argon atmosphere , which included two collector electrodes made of aluminium and two working electrodes of 17 . 7 mm in diameter made of activated carbon cloth and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising a mixture of 0 . 5 m ( dedaco ) 2 − ( bf 4 − ) 2 and 0 . 5 m ( dbdaco ) 2 − ( bf 4 −) 2 in acetonitrile . then the mockup was cycled within the range of 1 . 7 - 3 . 5 v under constant current conditions ( 3 or 10 ma ), and its capacitance and inner resistance values were determined at room temperature from the charging / discharge curves . the results are presented in table 2 . an edlc mockup was assembled under an argon atmosphere in a specially designed polypropylene cell , which included twenty four collector electrodes made of aluminium and twenty four working electrodes 15 × 15 cm made of activated carbon cloth connected in parallel and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising a mixture of 0 . 7 m tea + bf 4 − and 0 . 8 m ( dedaco ) 2 + ( bf 4 − ) 2 in acetonitrile . amount of the electrolyte was 480 ml , total weight of the mockup about 1 kilo including the case . this mockup was trained over a long period — first at 2 . 5 v for 7 weeks , and then its voltage was stepwise risen up to 2 . 8 - 2 . 9 v and kept at this voltage for 13 more weeks . the parameters of the cell , such as its capacitance , equivalent series resistance and self - discharge , were monitored but neither colour change nor deterioration of the cell parameters was found over the whole period of the experiments . a cycling curve obtained at the end of these long - term experiments under constant current conditions ( 10 a ) using an atg testing unit is presented in fig4 . an edlc mockup was assembled under an argon atmosphere , which included two collector electrodes made of aluminium and two working electrodes of 17 . 7 mm in diameter made of activated carbon cloth and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising 1 . 0 m tea + bf 4 − in acetonitrile . then the mockup was cycled within the range of 1 . 7 - 3 . 2 v under constant current conditions ( 3 or 10 ma ), and its capacitance and inner resistance values were determined at room temperature from the charging / discharge curves . the results are presented in table 2 . an edlc mockup was assembled under an argon atmosphere , which included two collector electrodes made of aluminium and two working electrodes of 17 . 7 mm in diameter made of activated carbon cloth and interleaved with a separator made of nonwoven polypropylene . the working electrodes and the separator were soaked in the electrolyte comprising 1 . 0 m diethylpyrazine ( see formula iii above ) in acetonitrile . this mockup was cycled within the range of 1 . 7 - 2 . 8 v under constant current conditions ( 3 or 10 ma ), and at higher voltages its leakage current started increasing so rapidly that those voltages could not be chosen as working ones . the result is presented in table 2 . it should also be noted that electrochemical windows for dedaco and tea ( analog ) tetrafluoroborates were recorded and compared — see fig3 . the data were obtained using the cyclic voltammetry on a toray glassy carbon electrode having the diameter of 2 mm ; scan rate 5 mv / s . zero value on this figure corresponds to zero charge potential of a glassy carbon electrode in acetonitrile . as can be seen from the figure , the dedaco based electrolyte provides a wider and more symmetrical electrochemical window than the analog chosen . this results in higher working voltage of edlc devices based on dedaco electrolytes , namely , 3 . 2 - 3 . 5 v compared to 2 . 8 - 3 . 2 v if tea is used . such an increase in working voltage , in its turn , results in 20 - 30 % higher energy stored in an edlc device . although the invention has been described with regard to its preferred embodiments , which constitute the best mode presently known to the inventors , it should be understood that various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the scope of the invention which is set forth in the claims appended hereto .