Overcharge and overdischarge protection of ambient temperature secondary lithium cells
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsChen-kuo Huang, Subbarao Surampudi, Alan I. Attia, Gerald Halpert
Life of this patent
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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 Li.sub.2 Mn.sub.2 O.sub.4 and Li.sub.0.1 MoO.sub.2.
Claims22
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.
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 Li.sub.x Mn.sub.2 O.sub.4, Li.sub.x MoO.sub.2, Li.sub.x CoO.sub.2, Li.sub.x NiO.sub.2, and Li.sub.x M.sub.y Mn.sub.(2-y) O.sub.4, wherein M is Co, Cr, or Fe, said secondary lithium cell being of a type selected from a group consisting of Li--TiS.sub.2, Li--MOS.sub.2, Li--NbSe.sub.3, Li--V.sub.2 O.sub.5, Li--MnO.sub.2, and Li.sub.x C--Li.sub.x CoO.sub.2, 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.
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 Li.sub.2 Mn.sub.2 O.sub.4 and Li.sub.0.1 MoO.sub.2, said secondary lithium cell being a Li--TiS.sub.2 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.
Dependencies are inferred from the claim text.