Method of charging alkali metal polymer batteries

• US 20060012335A1
• Filed: 07/19/2004
• Published: 01/19/2006
• Est. Priority Date: 07/19/2004
• Status: Active Grant

• Current Assignee: Bathium Canada Inc. (Bolloré SE)
• Original Assignee: Bathium Canada Inc. (Bolloré SE)
• Inventors: Gagnon, Philippe, Parent, Michel, Vaillancourt, Jean-Pierre
• Granted Patent: US 7,307,402 B2
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits

Abstract

A method of charging an electrochemical generator having a plurality of electrochemical cells. The method includes the step of charging the plurality of electrochemical cells such that the total voltage of the generator reaches a predetermined voltage level, followed by the steps of selecting a particular electrochemical cell and charging the particular electrochemical cell to its respective maximum voltage, such that the cathode(s) of the particular electrochemical cell is(are) restored to a fully-charged state. Once it has been restored to its fully-charged state, the particular electrochemical cell is allowed to discharge itself down to a nominal voltage. Each of the plurality of electrochemical cells of the generator is selected and charged to its respective maximum voltage in turn, according to a predetermined selection sequence.

Claims

1. A method of charging an electrochemical generator having a plurality of electrochemical cells, each electrochemical cell including at least one cathode, at least one anode and at least one electrolyte separator therebetween, the electrochemical generator being characterized by a total voltage, each electrochemical cell being associated with a respective maximum voltage, said method comprising:

a) charging the plurality of electrochemical cells such that the total voltage of the electrochemical generator reaches a predetermined voltage level;

b) selecting a particular electrochemical cell of the electrochemical generator; and

c) charging the particular electrochemical cell to its respective maximum voltage, thereby restoring the at least one cathode of the particular electrochemical cell to a fully-charged state.

2. A method as defined in claim 1, further comprising applying steps b) and c) to each one of the plurality of electrochemical cells of the generator in turn, according to a predetermined selection sequence.

3. A method as defined in claim 2, further comprising the step of allowing each particular electrochemical cell to discharge itself down to a nominal voltage after it has been restored to the fully-charged state.

4. A method as defined in claim 3, further comprising maintaining each particular electrochemical cell at its respective maximum voltage for a predetermined period of time before allowing the particular electrochemical cell to discharge itself down to the nominal voltage.

5. A method as defined in claim 1, wherein charging of the particular electrochemical cell occurs in spurts.

6. A method as defined in claim 2, wherein the plurality of electrochemical cells of the generator are arranged in a stack, each electrochemical cell being characterized by a respective position within the stack, the predetermined selection sequence being based on the positions of the electrochemical cells within the stack.

7. A method as defined in claim 6, wherein the predetermined selection sequence is based on a random choice of positions within the stack of electrochemical cells.

8. A method as defined in claim 6, wherein the predetermined selection sequence is based on an ordered choice of positions within the stack of electrochemical cells.

9. A method as defined in claim 1, wherein the predetermined voltage level is a preset voltage limit of an application load of the electrochemical generator, said method further including the step of reducing via discharge the voltage of each of the remaining, non-selected electrochemical cells of the electrochemical generator before charging the particular electrochemical cell to its respective maximum voltage, in order to ensure that the sum of the voltages of the plurality of electrochemical cells does not exceed the preset voltage limit of the application load.

10. A method as defined in claim 1, further including the step of controllably discharging the particular electrochemical cell to a predetermined voltage level that is lower than the maximum voltage of the particular electrochemical cell.

11. A method as defined in claim 1, wherein the predetermined voltage level divided by the number of electrochemical cells comprised in the electrochemical generator is comprised into a range of about 2.8 Volts to about 3.2 Volts.

12. An electrochemical generator comprising at least two electrochemical cells and an electronic control system, said electronic control system being operative to implement the method defined in claim 1.

13. An electrochemical generator comprising at least two electrochemical cells and an electronic control system, said electronic control system being operative to charge the generator such that each electrochemical cell of the generator is restored to its respective original chemical state.