Metal-air accumulator with air electrode protection device
AssigneeElectricite de France
InventorsGwenaelle Toussaint, Philippe Stevens, Bernard Toussaint
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Abstract
The present invention relates to a rechargeable accumulator comprising one or more metal-air cells, each cell comprising a metallic negative electrode, a first positive electrode for releasing oxygen, a second positive electrode which is a porous air electrode containing at least one oxygen reducing catalyst, and an automatic device for protecting the air electrode during the charging and discharging phases of the accumulator. The invention also relates to a method for storing and releasing electrical energy using such an accumulator.
Claims11
A rechargeable accumulator comprising one or more metal-air cells, each cell comprising
- a first terminal and a second terminal,
- a metal negative electrode for a metal-air cell, connected to the first terminal
- a first positive oxygen-releasing electrode,
- a second positive electrode, which is a porous air electrode containing at least one oxygen reducing catalyst, and
- an electrolyte,
- a control circuit adapted to continuously compare a measured voltage between the second terminal and the first terminal to a setpoint value and to send a switch signal to switching means when the measured voltage falls below the setpoint value,
- a commutator adapted to receive a switch signal originating from the control and to connect and disconnect the air electrode from the second terminal.
A method for storing and releasing electrical energy using an accumulator as claimed in any one of the preceding claims, said method comprising the following successive steps:
- (a) a charging phase during which the negative electrode is connected to the first terminal, the first positive electrode connected to the second terminal and the air electrode is disconnected,
- (b) a first discharging phase during which the negative electrode is connected to the first terminal, the first positive electrode is connected to the second terminal, the air electrode is disconnected, and the control continuously compares the measured voltage between the terminal and the first terminal to a setpoint value,
- (c) a first switching step during which the second positive electrode, which is the air electrode, is connected to the second terminal when the value of the voltage between the second terminal and the first terminal falls below the setpoint value,
- (d) a second discharging phase during which the negative electrode is connected to the first terminal, and the air electrode is connected to the second terminal, and
- (e) a second switching step during which the air electrode (5) is disconnected from the second terminal.
Dependencies are inferred from the claim text.