Overcharge and overdischarge protection of ambient temperature secondary lithium cells
First Claim
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1. In a secondary lithium cell susceptible to over-charging or overdischarging, the improvement being:
- a cathode additive for incorporating into a cathode of the cell, the cathode having a charge cutoff voltage and a discharge cutoff voltage, the cathode additive yielding an upper voltage plateau within the cell upon the application of an overcharge voltage to the cell, said upper voltage plateau being slightly higher than the charge cutoff voltage of the cathode and yielding a lower voltage plateau within the cell upon the application of an overdischarge voltage to the cell, said lower voltage plateau being slightly lower than the discharge cutoff voltage plateau of the cathode.
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Abstract
A cathode additive is provided for protecting an ambient temperature secondary lithium cell from over-charging or over-discharging. The cathode additive is chosen to create an upper voltage plateau which is slightly higher than a characteristic charge cutoff voltage of the cathode of the cell. The cathode additive additionally creates a lower voltage plateau which is slightly lower than the characteristic discharge cutoff voltage of the cell. Preferably the cathode additive is a transition metal oxide or a sulfide may, for example, include a mixture of Li2 Mn2 O4 and Li0.1 MoO2.
69 Citations
22 Claims
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1. In a secondary lithium cell susceptible to over-charging or overdischarging, the improvement being:
a cathode additive for incorporating into a cathode of the cell, the cathode having a charge cutoff voltage and a discharge cutoff voltage, the cathode additive yielding an upper voltage plateau within the cell upon the application of an overcharge voltage to the cell, said upper voltage plateau being slightly higher than the charge cutoff voltage of the cathode and yielding a lower voltage plateau within the cell upon the application of an overdischarge voltage to the cell, said lower voltage plateau being slightly lower than the discharge cutoff voltage plateau of the cathode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In a multicell rechargeable lithium battery susceptible to over-charging and overdischarging, the improvement being:
a cathode additive for incorporating into a cathode of each cell of the multicell battery, said cathode additive selected from a group consisting of Lix Mn2 O4, Lix MoO2, Lix CoO2, Lix NiO2, and Lix My Mn.sub.(2-y) O4, wherein M is Co, Cr, or Fe, said secondary lithium cell being of a type selected from a group consisting of Li--TiS2, Li--MOS2, Li--NbSe3, Li--V2 O5, Li--MnO2, and Lix C--Lix CoO2, each cathode having a charge cutoff voltage and a discharge cutoff voltage, the cathode additive yielding an upper voltage plateau within each respective cell upon the application of an overcharge voltage to the respective cell, said upper voltage plateau being slightly higher than the charge cutoff voltage of the cathode of the respective cell and yielding a lower voltage plateau within each respective cell upon the application of an over-discharge voltage to the respective cell, said lower voltage plateau being slightly lower than the discharge cutoff voltage plateau of the cathode of the respective cell. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. In a multicell rechargeable solid state lithium battery susceptible to over-charging and overdischarging, the improvement being:
a cathode additive for incorporating into a cathode of each cell of the multicell battery, said cathode additive being a mixture of Li2 Mn2 O4 and Li0.1 MoO2, said secondary lithium cell being a Li--TiS2 cell, each cathode having a charge cutoff voltage of about 2.7 volts and a discharge cutoff voltage of about 1.7 volts, the cathode additive yielding an upper voltage plateau of about 2.9 volts within each respective cell upon the application of an overcharge voltage to the respective cell, and yielding a lower voltage plateau of about 1.6 volts within each respective cell upon the application of an overdischarge voltage to the respective cell.
Specification