Lithium Ion Battery Charging Voltage Compensation
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Solution Overview
Problem
Current quick charge methods for lithium ion batteries are inefficient due to the difficulty in measuring various impedances, leading to prolonged charging times and potential side effects from incorrect limit voltages.
Innovation Solution
A method that rapidly and accurately determines the voltage drop caused by ohmic, concentration polarization, and electrochemical impedances, allowing for an increased charge limit voltage to compensate for these drops, thereby enabling faster charging while ensuring cycle performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the charge limit voltage is increased to achieve quick charge, then charging time is reduced, but side effects occur inside the battery
Solution Approach 1:
The patent performs preliminary measurement of the battery's internal resistance before charging. Based on this pre-measured resistance value, the charge limit voltage is dynamically adjusted to compensate for voltage drop during charging. This preliminary action allows the system to set an appropriate higher limit voltage that achieves quick charging without causing harmful side effects, as the adjustment is based on actual battery conditions rather than fixed values.
2Productivity
If the charge limit voltage is set too high, then quick charge is achieved, but the battery is overcharged and side effects occur
Solution Approach 1:
The patent implements a feedback mechanism where the charge limit voltage is adjusted based on the measured internal resistance of the battery. The system measures the internal resistance, calculates the voltage drop (V=IR), and sets the charge limit voltage accordingly (V_limit = V_ocv + V_drop). This feedback loop ensures that the limit voltage is high enough to achieve quick charging but not so high as to cause overcharging, thus maintaining both charging speed and battery safety.
3Reliability
If the charge limit voltage is set too low, then battery safety is maintained, but the battery is hardly fully charged
Solution Approach 1:
The patent changes the charge limit voltage parameter dynamically based on the battery's internal resistance characteristics. Instead of using a fixed limit voltage, the system measures the internal resistance and adjusts the limit voltage parameter to compensate for voltage drop. This parameter change allows the battery to be charged to full capacity without compromising safety, as the limit voltage is optimized according to actual battery conditions.
4Reliability
If constant current-constant voltage charging mode is used, then battery safety is ensured, but charging time is prolonged
Solution Approach 1:
The patent performs preliminary measurement of internal resistance before charging and uses this information to set an optimized charge limit voltage from the beginning. This allows the system to maintain constant current charging at a higher limit voltage throughout the charging process, avoiding the prolonged constant voltage phase required by traditional methods. The preliminary resistance measurement enables safe quick charging without transitioning to constant voltage mode.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces charging time while maintaining battery safety and cycle life, allowing for more efficient charging with minimal impact on battery longevity.
Implementation Method 1
the ohmic resistance, concentration polarization impedance, electrochemical polarization impedance and all other unknown impedances inside the battery will consume a part of the voltage
Implementation Method 2
the ohmic resistance, concentration polarization impedance, electrochemical polarization impedance and all other unknown impedances inside the battery will consume a part of the voltage
Implementation Method 3
the ohmic resistance, concentration polarization impedance, electrochemical polarization impedance and all other unknown impedances inside the battery will consume a part of the voltage
Data Source
AI summary
The present invention provides a quick charge method belonging to the field of the battery and particularly relates to a quick charge method for lithium ion battery and polymer lithium ion battery. During a battery is being charged, the battery stops charging when the battery is charged to a charge limit voltage, and the charge limit voltage between two poles of the battery is set to be U=2U0−Us, and Us is a stabilized voltage which the voltage of the battery falls back to after the voltage of the battery is charged to U0 at a constant current, U0 is a standard charge cutoff voltage used by a low rate constant current-constant voltage charging mode which is normally accepted by the industries, and the stabilized voltage Us is selected as follows: timing begins when the battery stops charging at the constant current, and from a certain time segment, when the drop of an open-circuit voltage of the battery is less than a certain value within the certain time segment, which means that the voltage of the battery is stable, and a voltage corresponding to the first time point of this time segment is selected as the stabilized voltage Us of the battery.