(JP10510661-W)      A non-aq. electrolyte system for use in batteries, capacitors or electrochromic displays comprises: (a) an alkali or ammonium salt; (b) a solvent mixt. comprising a mixt. of: (i) ethylene carbonate (EC); (ii) gamma-valerolactone (GVL); and opt. (iii) additional solvents selected from other organic carbonates, other lactones, ester and glymes; and opt. (c) a polymer. The system is opt. confined in a separator.    Also claimed is a method for the prepn. of the above electrolyte system comprising mixing the solvents, dissolving the salts in the mixt. and opt. adding a thickening agent to the soln..    USE -   The electrolyte is used in lithium batteries, supercapacitors, electrochromic devices such as 'smart windows'.    ADVANTAGE -   The system can be used for a broad voltage range, it has a conductivity higher than 10-3 S/cm at room temp. and it has a high stability against redn. in addition to a high oxidn. stability. It allows the construction of rechargeable lithium batteries with a cell voltage above 4V and supercapacitors with a cell voltage above 3V. The solvent mixt. combines the pref. characteristics of (i) and (ii) and provides high electrochemical stability against the negative electrode and forms a high performance passivation layer. It shows a lower irreversible loss of active material and a superior cycling efficiency w.r.t. prior art EC/gamma-butyrolactone mixts. and the capacity of an electrochemical cell is sustained through a high number of cycles.    (EP796510-B1)      A non-aq. electrolyte system for use in batteries, capacitors or electrochromic displays comprises: (a) an alkali or ammonium salt; (b) a solvent mixt. comprising a mixt. of: (i) ethylene carbonate (EC); (ii) gamma-valerolactone (GVL); and opt. (iii) additional solvents selected from other organic carbonates, other lactones, ester and glymes; and opt. (c) a polymer. The system is opt. confined in a separator.    Also claimed is a method for the prepn. of the above electrolyte system comprising mixing the solvents, dissolving the salts in the mixt. and opt. adding a thickening agent to the soln..    USE -   The electrolyte is used in lithium batteries, supercapacitors, electrochromic devices such as 'smart windows'.    ADVANTAGE -   The system can be used for a broad voltage range, it has a conductivity higher than 10-3 S/cm at room temp. and it has a high stability against redn. in addition to a high oxidn. stability. It allows the construction of rechargeable lithium batteries with a cell voltage above 4V and supercapacitors with a cell voltage above 3V. The solvent mixt. combines the pref. characteristics of (i) and (ii) and provides high electrochemical stability against the negative electrode and forms a high performance passivation layer. It shows a lower irreversible loss of active material and a superior cycling efficiency w.r.t. prior art EC/gamma-butyrolactone mixts. and the capacity of an electrochemical cell is sustained through a high number of cycles.    (US6045951-A)      A non-aq. electrolyte system for use in batteries, capacitors or electrochromic displays comprises: (a) an alkali or ammonium salt; (b) a solvent mixt. comprising a mixt. of: (i) ethylene carbonate (EC); (ii) gamma-valerolactone (GVL); and opt. (iii) additional solvents selected from other organic carbonates, other lactones, ester and glymes; and opt. (c) a polymer. The system is opt. confined in a separator.    Also claimed is a method for the prepn. of the above electrolyte system comprising mixing the solvents, dissolving the salts in the mixt. and opt. adding a thickening agent to the soln..    USE -   The electrolyte is used in lithium batteries, supercapacitors, electrochromic devices such as 'smart windows'.    ADVANTAGE -   The system can be used for a broad voltage range, it has a conductivity higher than 10-3 S/cm at room temp. and it has a high stability against redn. in addition to a high oxidn. stability. It allows the construction of rechargeable lithium batteries with a cell voltage above 4V and supercapacitors with a cell voltage above 3V. The solvent mixt. combines the pref. characteristics of (i) and (ii) and provides high electrochemical stability against the negative electrode and forms a high performance passivation layer. It shows a lower irreversible loss of active material and a superior cycling efficiency w.r.t. prior art EC/gamma-butyrolactone mixts. and the capacity of an electrochemical cell is sustained through a high number of cycles.