LITHIUM SECONDARY BATTERY AND CONTROL SYSTEM THEREFOR, AND METHOD FOR DETECTING STATE OF LITHIUM SECONDARY BATTERY
First Claim
1. A control system for a lithium secondary battery comprising a positive electrode, a negative electrode using silicon oxide as a negative electrode active material, and means for obtaining a potential of the negative electrode with respect to a lithium reference electrode, the control system comprising:
- measurement means for measuring a voltage V of the negative electrode with respect to the 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.
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Accused Products
Abstract
There is provided a control system for a lithium secondary battery that can quantitatively sense a deterioration state inherent in a lithium secondary battery using silicon oxide as a negative electrode active material, that is, the nonuniform reaction state of a negative electrode. A control system for a lithium secondary battery including a positive electrode, a negative electrode using silicon oxide as a negative electrode active material, and a lithium reference electrode having a reference potential with respect to the negative electrode includes measurement means for measuring a voltage V of the negative electrode with respect to the 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.
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Citations
20 Claims
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1. A control system for a lithium secondary battery comprising a positive electrode, a negative electrode using silicon oxide as a negative electrode active material, and means for obtaining a potential of the negative electrode with respect to a lithium reference electrode, the control system comprising:
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measurement means for measuring a voltage V of the negative electrode with respect to the 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A lithium secondary battery comprising a positive electrode, a negative electrode using silicon oxide as a negative electrode active material, and a lithium reference electrode having a reference potential with respect to the 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 the 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, wherein the charge and discharge control portion receiving the transmission executes means for improving a degree of uniformity of lithium concentration in the negative electrode. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for detecting a state of a lithium secondary battery comprising a positive electrode, a negative electrode using silicon oxide as a negative electrode active material, and a lithium reference electrode having a reference potential with respect to the negative electrode, the method comprising:
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a measurement step of measuring a voltage V of the negative electrode with respect to the 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; and a sensing step of sensing a state of the negative electrode utilizing the intensity ratio. - View Dependent Claims (19, 20)
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Specification