Process for conditioning an electrochemical cell

Details Process for conditioning an electrochemical cell Process for conditioning an electrochemical cell

1999-07-28

2001-07-31

Chaney, Carol (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

Current producing cell, elements, subcombinations and...

Include electrolyte chemically specified and method

C429S305000, C429S303000, C429S306000, C429S307000, C429S322000, C429S324000, C429S231950

Reexamination Certificate

active

06268080

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to electrochemical cells, and more particularly, to a process for conditioning an electrochemical cell in the presence of an additive at elevated temperatures.
2. Background Art
Conventional electrochemical cells are conditioned, prior to normal use, by cycling (i.e. charging and discharging) the electrochemical cell several times in a controlled fashion. During conditioning of the of the electrochemical cell, a solid electrolyte interface (SEI) or passivation layer is formed. The formation of the passivation layer occurs when an electrolyte component, such as an additive undergoes one or more chemical changes including reduction or decomposition. Once a stable passivation layer has been formed the electrochemical cell can be cycled, or put into normal operation, in a safe and reliable manner.
While a passivation layer serves a valuable purpose during operation of an electrochemical, the conventional process used to form the passivation layer is not without its drawbacks. First, in order to properly form the passivation layer the cell must be cycled several times, which increases conditioning time and overall cost of manufacturing the cell. Second, a portion of the cell's capacity is consumed during the formation of the passivating layer, which directly results in a loss of energy density of the cell.
It is therefore an object of the present invention to provide a process for conditioning an electrochemical cell that remedies the aforementioned complications and/or detriments associated with conventional conditioning techniques.
SUMMARY OF THE INVENTION
The present invention is directed to a process for conditioning an electrochemical cell comprising the steps of: (a) fabricating an electrochemical cell comprising a first electrode, a second electrode, and an electrolyte; (b) associating an additive with the electrochemical cell; (c) elevating the temperature of the electrochemical cell; and (d) cycling the electrochemical cell, and in turn, forming a passivation layer at an interface between one of the electrodes and the electrolyte.
In a preferred embodiment of the invention, the step of elevating the temperature of the electrochemical cell comprises the step of heating the cell to between approximately 45 degrees centigrade and approximately 100 degrees centigrade.
In another preferred embodiment of the invention, the step of elevating the temperature of the electrochemical cell comprises the step of heating the cell to between approximately 65 degrees centigrade and approximately 85 degrees centigrade.
The step of associating an additive with the electrochemical cell preferably comprises the step of introducing an additive selected from at least one of the group consisting essentially of THPA, bicyclo-octene dianhydride, CPDA, succinic anhydride, 1,6-spiro, vinylene carbonate and mixtures thereof into the electrolyte.
Preferably the process further includes the step of increasing the coulombic efficiently of the electrochemical cell relative to an electrochemical cell cycled at ambient temperature.
In a preferred embodiment of the invention, the step of fabricating the electrochemical cell comprises the steps of: (a) associating a carbonaceous electrode with a lithium transition metal oxide electrode; and (b) positioning an organic solvent with between the electrodes.


REFERENCES:
patent: 5846673 (1998-12-01), Saidi et al.
patent: 5853917 (1998-12-01), Fauteux et al.
patent: 5861224 (1999-01-01), Barker et al.

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