Accurate Assessment of the State of Charge of Electrochemical Cells
First Claim
1. A method for characterizing the state of charge of an electrochemical cell, said method comprising the steps of:
- generating a multidimensional state of charge profile corresponding to said electrochemical cell;
measuring a plurality of open circuit voltages of said electrochemical cell corresponding to a plurality of temperatures of said electrochemical cell;
determining a plurality of thermodynamic parameters corresponding to said electrochemical cell, wherein said thermodynamic parameters are selected from the group comprising;
a change in enthalpy (Δ
H), a change in entropy (Δ
S) and a change in free energy (Δ
G); and
characterizing said state of charge of said electrochemical cell using said multidimensional state of charge profile and said thermodynamic parameters.
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Abstract
Provided are methods, systems and devices for thermodynamically evaluating electrochemical systems and components thereof, including electrochemical cells such as batteries. The present systems and methods are capable of monitoring selected electrochemical cell conditions, such as temperature, open circuit voltage and/or composition, and carrying out measurements of a number of cell parameters, including open circuit voltage, time and temperature, with accuracies large enough to allow for precise determination of thermodynamic state functions and materials properties relating to the composition, phase, states of charge, health and safety and electrochemical properties of electrodes and electrolytes in an electrochemical cell. Thermodynamic measurement systems of the present invention are highly versatile and provide information for predicting a wide range of performance attributes for virtually any electrochemical system having an electrode pair.
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Citations
65 Claims
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1. A method for characterizing the state of charge of an electrochemical cell, said method comprising the steps of:
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generating a multidimensional state of charge profile corresponding to said electrochemical cell; measuring a plurality of open circuit voltages of said electrochemical cell corresponding to a plurality of temperatures of said electrochemical cell; determining a plurality of thermodynamic parameters corresponding to said electrochemical cell, wherein said thermodynamic parameters are selected from the group comprising;
a change in enthalpy (Δ
H), a change in entropy (Δ
S) and a change in free energy (Δ
G); andcharacterizing said state of charge of said electrochemical cell using said multidimensional state of charge profile and said thermodynamic parameters. - View Dependent Claims (4, 5, 7, 8, 9, 10, 11, 13, 15, 16, 17, 19, 20, 21, 22, 25, 27)
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2-3. -3. (canceled)
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6. (canceled)
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12. (canceled)
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18. (canceled)
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23-24. -24. (canceled)
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26. (canceled)
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28. (canceled)
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29. A measurement system for thermodynamically characterizing a state of charge of an electrochemical cell;
- said system comprising;
a temperature analyzer for measuring or receiving temperature measurements of said electrochemical cell; an open circuit voltage analyzer for measuring open circuit voltages corresponding to a plurality of different temperatures of said electrochemical cell; a thermodynamic parameter processor positioned in data communication with said temperature analyzer and said open circuit voltage analyzer, said processor programmed to determine thermodynamic parameters based on said open circuit voltage measurements and said temperature measurements;
wherein said thermodynamic parameters are selected from the group comprising;
a change in enthalpy (Δ
H), a change in entropy (Δ
S) and a change in free energy (Δ
G); anda state of charge processor positioned in data communication with said temperature analyzer and said open circuit voltage analyzer, said processor programmed to characterize said state of charge of said electrochemical cell using said plurality of said thermodynamic parameters and a multidimensional state of charge profile. - View Dependent Claims (32, 35, 36, 40, 42, 45, 49, 50)
- said system comprising;
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30-31. -31. (canceled)
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37-39. -39. (canceled)
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51-59. -59. (canceled)
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60. A device for monitoring the state of charge of an electrochemical cell, said device comprising:
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a temperature monitoring circuit for measuring a plurality of temperatures of said electrochemical cell; a voltage monitoring circuit for measuring a plurality of open circuit voltages of said electrochemical cell corresponding to said plurality of temperatures, said plurality of open circuit voltages generated upon charging or discharging said electrochemical cell or stopping charging or discharging said electrochemical cell; a thermodynamic measurement circuit for determining thermodynamic parameters of said electrochemical cell, wherein said thermodynamic parameters are change in enthalpy (Δ
H) of said electrochemical cell, a change in entropy (Δ
S) of said electrochemical cell and/or a change in free energy of said electrochemical cell (Δ
G);
wherein said thermodynamic measurement circuit is positioned in electrical or data communication with said voltage monitoring circuit to receive said open circuit voltage measurements and positioned in electrical or data communication with said temperature monitoring circuit to receive said temperatures; anda state of charge calculating circuit for determining the state of charge of said electrochemical cell positioned in electrical or data communication with said thermodynamic circuit to receive said thermodynamic parameters;
wherein said state of charge calculating circuit determines a state of charge of said electrochemical cell using said thermodynamic parameters and a multidimensional state of charge profile for said electrochemical cell. - View Dependent Claims (63, 64)
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61-62. -62. (canceled)
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65-69. -69. (canceled)
Specification