Deep-discharge conditioning for lithium-ion cells
AssigneeNavitas Systems, LLC
InventorsPu Zhang, Viet H. Vu, Hongxia Zhou, Patrick L. Hagans, Michael Wixom
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Abstract
A process of reconditioning a lithium-ion cell is provided that unexpectedly improves cell capacity, reduces cold temperature impedance and increases cold cranking amps. The process involves a reconditioning step of holding a cell at a sub-discharge voltage for a recovery time. The sub-discharge voltage is 1.0V or less in many embodiments, optionally 0.0V. Holding this sub-discharge voltage for a recovery time of several hours will result in recovery of lost capacity that is in excess of that explainable by recovery of ions transferred to an anode overhang.
Claims20
A process for reconditioning an electrochemical cell comprising:
- holding a lithium-ion cell at a sub-discharge voltage of 2.0 Volts or less for a recovery time sufficient to show an increased capacity relative to an untreated cell.
A process increasing cranking amperes of an electrochemical cell at a temperature less than 25 degrees Celsius comprising:
- holding a lithium-ion cell at a sub-discharge voltage of 2.0 Volts or less for a recovery time sufficient to show increased cranking amperes of an electrochemical cell at 0 degrees Celsius or lower relative to an untreated cell.
A process of increasing the cycle life of a lithium-ion cell comprising:
- cycling a lithium-ion cell between a charge voltage and a discharge voltage for a first cycling period;
- and
- holding said lithium-ion cell at a sub-discharge voltage of 2.0 Volts or less for a recovery time sufficient to show an increased capacity for 10 or more cycles.
Dependencies are inferred from the claim text.