Electrochemical thermodynamic measurement system
First Claim
1. A measurement system for thermodynamically evaluating an electrochemical cell having electrodes;
- said system comprising;
a means for measuring open circuit voltages of said electrochemical cell as a function of time;
a composition controller electrically connected to said electrochemical cell for establishing selected electrochemical cell compositions, said composition controller configured for establishing a plurality of said selected compositions;
a temperature controller in thermal contact with said electrochemical cell for establishing a plurality of selected electrochemical cell temperatures for each of said selected compositions, thereby establishing a plurality of selected electrochemical cell temperature and composition combinations; and
an open circuit voltage analyzer for receiving open circuit voltage measurements as a function of time from said means for measuring open circuit voltages and for identifying open circuit voltages for thermochemically stabilized conditions of said electrochemical cell for said selected electrochemical cell temperature and composition combinations,wherein one of said electrodes is an intercalating electrode and the selected electrochemical cell compositions correspond to different stoichiometries of an intercalant incorporated with said intercalating electrode of said electrochemical cell.
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Abstract
The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement 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 electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.
50 Citations
60 Claims
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1. A measurement system for thermodynamically evaluating an electrochemical cell having electrodes;
- said system comprising;
a means for measuring open circuit voltages of said electrochemical cell as a function of time; a composition controller electrically connected to said electrochemical cell for establishing selected electrochemical cell compositions, said composition controller configured for establishing a plurality of said selected compositions; a temperature controller in thermal contact with said electrochemical cell for establishing a plurality of selected electrochemical cell temperatures for each of said selected compositions, thereby establishing a plurality of selected electrochemical cell temperature and composition combinations; and an open circuit voltage analyzer for receiving open circuit voltage measurements as a function of time from said means for measuring open circuit voltages and for identifying open circuit voltages for thermochemically stabilized conditions of said electrochemical cell for said selected electrochemical cell temperature and composition combinations, wherein one of said electrodes is an intercalating electrode and the selected electrochemical cell compositions correspond to different stoichiometries of an intercalant incorporated with said intercalating electrode of said electrochemical cell. - 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, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
- said system comprising;
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28. A method for thermodynamically evaluating an electrochemical cell having electrodes;
- said method comprising the steps of;
controlling the composition of said electrochemical cell to establish a plurality of selected electrochemical cell compositions; controlling the temperature of said electrochemical cell to establish a plurality of selected electrochemical cell temperatures for each of said selected electrochemical cell compositions, thereby establishing a plurality of selected electrochemical cell temperature and composition combinations; measuring open circuit voltages of said electrochemical cell as a function of time for said selected electrochemical cell compositions and said selected electrochemical cell temperatures; and identifying open circuit voltages for thermochemically stabilized conditions of said electrochemical cell for said selected electrochemical cell temperature and composition combinations, wherein at least one of said electrodes is an intercalating electrode, and the step of controlling the composition of said electrochemical cell establishes a selected stoichiometry of an intercalant in said intercalating electrode. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
- said method comprising the steps of;
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38. A measurement system for thermodynamically evaluating an electrochemical cell having electrodes;
- said system comprising;
a means for measuring open circuit voltages of said electrochemical cell as a function of time; a composition controller electrically connected to said electrochemical cell for establishing selected electrochemical cell compositions, said composition controller configured for establishing a plurality of said selected compositions; a temperature controller in thermal contact with said electrochemical cell for establishing a plurality of selected electrochemical cell temperatures for each of said selected compositions, thereby establishing a plurality of selected electrochemical cell temperature and composition combinations; and
an open circuit voltage analyzer for receiving open circuit voltage measurements as a function of time from said means for measuring open circuit voltages and for identifying open circuit voltages for thermochemically stabilized conditions of said electrochemical cell for said selected electrochemical cell temperature and composition combinations;
wherein said open circuit voltage analyzer is a processor configured for executing an algorithm that calculates observed rates of change in open circuit voltage per unit time for a selected electrochemical cell temperature and composition combination using said open circuit voltage measurements as a function of time received from said means of measuring open circuit voltage;
wherein said algorithm compares absolute values of said observed rates of change in open circuit voltage per unit time for said selected electrochemical cell temperature and composition combination to a threshold rate of change in open circuit voltage per unit time, and wherein said algorithm identifies an open circuit voltage equal to said open circuit voltage of said electrochemical cell for thermochemically stabilized conditions for said selected electrochemical cell temperature and composition combination when the absolute value of the observed rate of change in open circuit voltage per unit time is equal to or less than said threshold rate of change in open circuit voltage per unit time. - View Dependent Claims (39, 40)
- said system comprising;
Specification