Methods for thermodynamic evaluation of battery state of health
First Claim
1. A method of characterizing the state of health of an electrochemical cell comprising a host material, the method comprising the steps of:
- determining a change in Gibbs Free Energy (Δ
G), a change in Entropy(Δ
S), a change in Enthalpy (Δ
H) or any combination thereof of the electrochemical cell for a plurality of selected electrochemical cell compositions;
determining states of charge of the electrochemical cell for each of the plurality of selected electrochemical cell compositions;
identifying the states of charge and Δ
G, Δ
S, Δ
H or any combination thereof corresponding to an event or condition of the electrochemical cell; and
comparing the Δ
G, Δ
S, Δ
H or any combination thereof corresponding to the event or condition of the electrochemical cell to reference Δ
G, Δ
S, Δ
H or any combination thereof corresponding to the event or condition of a reference electrochemical cell;
wherein the event or condition is selected from the group consisting of;
a 0% charge state of the electrochemical cell, a 100% charge state of the electrochemical cell, a partial charge state of the electrochemical cell and a phase transition taking place within the electrochemical cell;
wherein the step of determining Δ
G, Δ
S, Δ
H or any combination thereof of the electrochemical cell for the plurality of selected electrochemical cell compositions comprises the steps of;
controlling the composition of the electrochemical cell to establish said plurality of selected electrochemical cell compositions;
controlling the temperature of the electrochemical cell to establish a plurality of selected electrochemical cell temperatures for each of the selected electrochemical cell compositions;
measuring open circuit voltages of the electrochemical cell as a function of time for the selected electrochemical cell compositions and temperatures; and
identifying open circuit voltages for thermochemically stabilized conditions of the electrochemical cell for the selected electrochemical cell compositions and temperatures.
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Abstract
Described are systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and battery systems and for characterizing the state of health of electrodes and battery systems. Measurement of physical attributes of electrodes and batteries corresponding to thermodynamically stabilized electrode conditions permit determination of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and battery systems, such as energy, power density, current rate, cycle life and state of health. Also provided are systems and methods for charging a battery according to its state of health.
62 Citations
33 Claims
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1. A method of characterizing the state of health of an electrochemical cell comprising a host material, the method comprising the steps of:
-
determining a change in Gibbs Free Energy (Δ
G), a change in Entropy(Δ
S), a change in Enthalpy (Δ
H) or any combination thereof of the electrochemical cell for a plurality of selected electrochemical cell compositions;determining states of charge of the electrochemical cell for each of the plurality of selected electrochemical cell compositions; identifying the states of charge and Δ
G, Δ
S, Δ
H or any combination thereof corresponding to an event or condition of the electrochemical cell; andcomparing the Δ
G, Δ
S, Δ
H or any combination thereof corresponding to the event or condition of the electrochemical cell to reference Δ
G, Δ
S, Δ
H or any combination thereof corresponding to the event or condition of a reference electrochemical cell;
wherein the event or condition is selected from the group consisting of;
a 0% charge state of the electrochemical cell, a 100% charge state of the electrochemical cell, a partial charge state of the electrochemical cell and a phase transition taking place within the electrochemical cell;wherein the step of determining Δ
G, Δ
S, Δ
H or any combination thereof of the electrochemical cell for the plurality of selected electrochemical cell compositions comprises the steps of;controlling the composition of the electrochemical cell to establish said plurality of selected electrochemical cell compositions; controlling the temperature of the electrochemical cell to establish a plurality of selected electrochemical cell temperatures for each of the selected electrochemical cell compositions; measuring open circuit voltages of the electrochemical cell as a function of time for the selected electrochemical cell compositions and temperatures; and identifying open circuit voltages for thermochemically stabilized conditions of the electrochemical cell for the selected electrochemical cell compositions and temperatures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification