Systems and control devices for charging and discharging lithium-ion battery, and relevant methods
Systems and control devices for charging and discharging a lithium-ion battery and relevant methods are provided. A variable frequency triggering oscillation charge-discharge device constructs an oscillation loop with a lithium-ion battery using an inherent impedance characteristic of the lithium-ion battery to charge and/or discharge the lithium-ion battery in the form of an oscillation current generated by the oscillation loop, to avoid direct current (DC) charge-discharge for the lithium-ion battery or battery pack that causes polarization and lithium precipitation of the lithium. Accordingly, the lithium-ion battery has longer battery life, higher charging threshold voltage, higher charge, and controlled internal temperature increase. Thus, the suitable temperature range for the lithium-ion battery is broadened.
1. A method of charging or discharging a lithium-ion battery comprising:
generating two or more oscillation currents by an oscillation loop formed based on an inherent impedance characteristic of the lithium-ion battery itself; and
charging the lithium-ion battery with a charging unit with the two or more oscillation currents according to one or more charging parameters, wherein the charging parameters are determined based on one or more status parameters of the lithium-ion battery; or
discharging the lithium-ion battery with a load with the two or more oscillation currents according to one or more discharging parameters, wherein the discharging parameters are determined based on one or more status parameters of the lithium-ion battery,
wherein:
the two or more oscillation currents comprise a first oscillation current and a second oscillation current;
the first oscillation current has a frequency range higher than a frequency range of the second oscillation current;
the duration T 2 of the first oscillation current is adjusted according to a temperature of the lithium-ion battery (a first battery temperature), and determined by the following formula:
T 2 =n/f g, wherein:
n=0 if the first battery temperature ≥a first working temperature desired for the charging or discharging of the lithium-ion battery; and
n=1+INT((the first working temperature−the first battery temperature)x′) if the first battery temperature <the first working temperature, wherein 0.01≤x′≤20, and INT is the integer-valued function; and
the lower limit f cd and upper limit f g of the frequency of the second oscillation current are determined by:
plotting a line parallel to the horizontal axis and through an intersection of EIS at the first working temperature and the vertical axis in the EIS plots with a first state of charge (SOC) in a frequency range; wherein:
the frequency f cd corresponds to the intersection of the EIS plot at the first battery temperature and the parallel line in the low frequency region; and
the frequency f g corresponds to the intersection of the EIS plot at the first battery temperature and the parallel line in the high frequency region.
2. The method of claim 1 , wherein the one or more status parameters selected from the group consisting of temperature, SOC, voltage, internal resistance, dimensional size, weight, type, appearance, structure, and material of the lithium-ion battery.
3. The method of claim 1 , wherein the first oscillation current and the second oscillation current are alternatively applied during charging/discharging.
4. A system for charging or discharging a lithium-ion battery, comprising:
a variable frequency triggering oscillation charging/discharging device, which forms an oscillation loop with the lithium-ion battery to generate two or more oscillation currents for charging or discharging the lithium-ion battery; and
a control device that controls the variable frequency triggering oscillation charging/discharging device to supply two or more oscillation currents to the lithium-ion battery according to temperature and a State of Charge (SOC) of the lithium-ion battery of the lithium-ion battery, wherein:
the variable frequency triggering oscillation charging/discharging device is to be coupled between a first charging device for charging or a load for discharging and the lithium-ion battery; and
the two or more oscillation currents include a first oscillation current and a second oscillation current, and the first oscillation current has a frequency range higher than that of the second oscillation current, wherein:
the duration T 2 of the first oscillation current is adjusted according to a temperature of the lithium-ion battery (a first battery temperature), and determined by the following formula:
T 2 =n/fg , wherein:
n=0 if the first battery temperature ≥a first working temperature desired for the charging or discharging of the lithium-ion battery; and
n=1+INT((the first working temperature−the first battery temperature)x′) if the first battery temperature <the first working temperature, wherein 0.01≤x′≤20, and INT is the integer-valued function; and
the lower limit f cd and upper limit f g of the frequency of the second oscillation current are determined by:
plotting a line parallel to the horizontal axis and through an intersection of EIS at the first working temperature and the vertical axis in the EIS plots with a first state of charge (SOC) in a frequency range; wherein:
the frequency f cd corresponds to the intersection of the EIS plot at the first battery temperature and the parallel line in the low frequency region; and
the frequency f g corresponds to the intersection of the EIS plot at the first battery temperature and the parallel line in the high frequency region.
5. The system of claim 4 , wherein the variable frequency triggering oscillation charging/discharging device comprises:
an energy storage and freewheeling unit connected to the first charging device and/or load in parallel;
an oscillation unit connected to the lithium-ion battery in parallel to form the oscillation loop; and
an oscillation trigger connected between the energy storage and freewheeling unit and the oscillation unit to trigger the oscillation loop to generate the two or more oscillation currents.
6. The system of claim 5 , wherein the oscillation trigger comprises an anti-paralleled diode.
7. The system of claim 5 , wherein the control device is a battery manage system (BMS) or a triggering controller.
8. The system of claim 4 , wherein the variable frequency triggering oscillation charging/discharging device comprises:
an energy storage and freewheeling unit connected to the first charging device and/or load in parallel;
an oscillation unit connected to the energy storage and freewheeling unit in series and then connected to the lithium-ion batteries in series to form the oscillation loop; and
an oscillation trigger connected to the oscillation unit in parallel to trigger the oscillation loop to generate the one or more oscillation currents.
9. The system of claim 8 , wherein the oscillation trigger comprises an anti-paralleled diode.
10. The system of claim 8 , wherein the control device is a battery manage system (BMS) or a triggering controller.