Xavier Andrieu

Plasticization of cross-linked polymer electrolytes

The plasticization of cross-linked poly(ethylene oxide)/poly(propylene oxide) copolymer electrolytes was investigated using low mol. wt. poly(ethylene oxide) PEO as plasticizer. These plasticizers were grafted on to the polymer networks (internal plasticization) or free (external plasticization). The conductivities of the plasticized polymer networks were measured at room temperature using LiClO4 as salt. Plasticization increased the conductivity and the gain depended on the plasticization-type, on the size of the plasticizer connected to the size of the copolymer and on the nature of the plasticizer. The glass-transition temperatures of the polymers were also measured and they varied in an opposite way versus conductivity.

New conducting polymer networks

Abstract These new polymer networks are based on cross-linked polyethers. The cross-link reaction is carried out by reaction of a diglycidyl compound with a polyether having two terminal primary amine groups. Ionic conductivity depends on the level of cross-linking, the salt concentration and the nature of the polyether. At room temperature, the best obtained conductivity exceeds 4 × 10 −5 S/cm. Mechanical properties are good. These polymer electrolytes are completely amorphous and stable up to 250 °C. The measured glass-transition temperature is close to −56 °C. These networks are also used to synthesize hybrid electrolytes which include a liquid polymer or a high dielectric constant solvent. The conductivity of these electrolytes is close to organic liquid electrolytes.

Method of charging a lithium storage cell having a carbone anode

The present invention provides a method of charging a carbon-anode lithium storage cell, which method comprises a first step in which a constant current is imposed and during which the voltage across said storage cell is allowed to increase until it reaches a reference value, and then a second step in which said reference voltage is imposed and said current decreases. The method of the invention is characterized in that, at each instant, said reference voltage is equal to the sum of the end-of-charge voltage of the cell plus the product of the current multiplied by the ohmic resistance of the cell.

Electrochemical characterization of new conducting polymer electrolytes

Abstract Prepared with bis-amino PEO/PPO copolymers, with and without amino PEO oligomers, and the cross-linking agent butanediol diglycidyl ether, a new series of cross-linked polymer electrolytes were investigated for their ionic conductivity and for the electrochemical properties of lithium cycleability and lithium polymer electrolyte compatibility. Room-temperature conductivity was found to be two order of magnitude higher than that of ‘conventional’ PEO-based electrolytes; compatibility with metallic lithium proved to be fairly good.

Method and apparatus for measuring the state of charge of an electrochemical cell pulse producing a high discharge current

The state of charge of an electrochemical storage unit is measured by applying to the electrochemical storage unit (32), a voltage pulse which is less than its nominal voltage, so as to make the storage unit deliver a high discharge current for a short period of time. The level of the voltage pulse is chosen to cause a discharge current that varies monotonically and preferably approximately linearly as a function of the state of charge of the storage unit, so that the state of charge can be unambiguously estimated by measuring the discharge current.