System and method for detecting a state of a lithium secondary battery by measuring a voltage of a negative electrode with respect to a reference electrode
First Claim
1. A control system for a lithium secondary battery comprising a positive electrode and a negative electrode, the control system comprising:
- measurement means for measuring a voltage V of the negative electrode with respect to a lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery;
generation means for generating a V−
dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V;
calculation means for calculating an intensity ratio of two peaks appearing on the V−
dQ/dV curve for two voltage values in the voltage V; and
sensing means for sensing a state of the negative electrode utilizing the intensity ratio, whereinthe discharge curve of a half cell comprising the positive electrode and a metal lithium negative electrode is previously measured, and the measurement means obtains the voltage V of the negative electrode with respect to the lithium reference electrode by calculation from the difference between the discharge curve of the lithium secondary battery and the discharge curve of the half cell.
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Accused Products
Abstract
A control system for a lithium secondary battery measures a voltage V of a negative electrode that uses silicon oxide as a negative electrode active material, with respect to a lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery; generates a V−dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V; calculates an intensity ratio of two peaks appearing on the V−dQ/dV curve for two voltage values in the voltage V; and senses a state of the negative electrode utilizing the intensity ratio.
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Citations
23 Claims
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1. A control system for a lithium secondary battery comprising a positive electrode and a negative electrode, the control system comprising:
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measurement means for measuring a voltage V of the negative electrode with respect to a lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery; generation means for generating a V−
dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V;calculation means for calculating an intensity ratio of two peaks appearing on the V−
dQ/dV curve for two voltage values in the voltage V; andsensing means for sensing a state of the negative electrode utilizing the intensity ratio, wherein the discharge curve of a half cell comprising the positive electrode and a metal lithium negative electrode is previously measured, and the measurement means obtains the voltage V of the negative electrode with respect to the lithium reference electrode by calculation from the difference between the discharge curve of the lithium secondary battery and the discharge curve of the half cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A lithium secondary battery comprising a positive electrode and a negative electrode, the lithium secondary battery comprising:
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a charge and discharge control portion for repeatedly charging and discharging the lithium secondary battery; a measurement portion for measuring a voltage V of the negative electrode with respect to a lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery; a generation portion for generating a V−
dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V;a peak intensity ratio calculation portion for calculating an intensity ratio of two peaks appearing on the V−
dQ/dV curve for two voltage values in the voltage V;a peak intensity ratio comparison portion for sensing a state of the negative electrode utilizing the intensity ratio; and an information transmission portion for transmitting, when the comparison portion senses that a difference between the intensity ratio of the two peaks appearing on the V−
dQ/dV curve for the two voltage values in the voltage V becomes equal to or more than a predetermined threshold, the information to the charge and discharge control portion, whereinthe charge and discharge control portion receiving the transmission executes means for improving a degree of uniformity of lithium concentration in the negative electrode, and wherein the discharge curve of a half cell comprising the positive electrode and a metal lithium negative electrode is previously measured, and the measurement portion obtains the voltage V of the negative electrode with respect to the lithium reference electrode by calculation from the difference between the discharge curve of the lithium secondary battery and the discharge curve of the half cell. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for detecting a state of a lithium secondary battery comprising a positive electrode and a negative electrode, the method comprising:
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a measurement step of measuring a voltage V of the negative electrode with respect to a lithium reference electrode and a discharge capacity Q of the lithium secondary battery during discharge of the lithium secondary battery; a generation step of generating a V−
dQ/dV curve representing a relationship between dQ/dV, which is a proportion of an amount of change dQ in the discharge capacity Q to an amount of change dV in the voltage V, and the voltage V;a calculation step of calculating an intensity ratio of two peaks appearing on the V−
dQ/dV curve for two voltage values in the voltage V; anda sensing step of sensing a state of the negative electrode utilizing the intensity ratio, wherein the discharge curve of a half cell comprising the positive electrode and a metal lithium negative electrode is previously measured, and in the measurement step, the voltage V of the negative electrode with respect to the lithium reference electrode is obtained by calculation from the difference between the discharge curve of the lithium secondary battery and the discharge curve of the half cell. - View Dependent Claims (21, 22, 23)
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Specification