Li-Ion Battery Charging Frequency Optimization
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Solution Overview
Problem
Existing battery charging technologies are inefficient at low temperatures, leading to reduced performance, energy delivery, and accelerated degradation in Li-Ion batteries, as they fail to optimize charging frequency in relation to temperature effects.
Innovation Solution
A method and system that determine the electrolyte resistance frequency and charge transfer resistance frequency using impedance spectroscopy, allowing for controlled charging with a current frequency between 10 Hz and 300 Hz, preferably 100 Hz, which is higher than the electrolyte resistance frequency and lower than the charge transfer resistance frequency, and adjusts this frequency based on temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional charging is used at low temperatures, then charging can be performed, but charging time increases and battery degradation accelerates
Solution Approach 1:
The patent applies periodic action by using a charge current that oscillates at a specific frequency (between 10³ Hz and a few hundred Hz) rather than a constant current. This periodic modulation of the charging current allows the battery to be charged more effectively at low temperatures, reducing both charging time and degradation by matching the oscillation frequency to the battery's impedance characteristics at different temperatures.
Solution Approach 2:
The patent employs parameter changes by adjusting the charge current frequency based on temperature conditions. The system modifies the frequency parameter of the charging current to match the battery's impedance spectrum at different temperatures, enabling optimized charging performance across varying temperature conditions while minimizing degradation.
2Productivity
If high frequency charge current (1 kHz) is used, then charging can be performed, but it corresponds to inductive impedance and does not improve low temperature performance
Solution Approach 1:
The patent applies dynamics by making the charge current frequency adaptive rather than fixed. The system dynamically adjusts the charging frequency based on the battery's temperature and impedance characteristics, transitioning from a static 1 kHz frequency to a dynamic frequency selection that optimizes charging efficiency at each temperature condition.
Solution Approach 2:
The patent uses parameter changes by modifying the charge current frequency parameter according to temperature conditions. Instead of using a fixed high frequency (1 kHz) that targets inductive impedance, the system changes the frequency parameter to match the battery's impedance spectrum at different temperatures, thereby improving both charging efficiency and temperature adaptability.
3Reliability
If constant voltage charging with voltage oscillation (a few mV) is used, then storage performance improves, but charging time is not optimized for low temperatures
Solution Approach 1:
The patent applies periodic action by using a charge current with significant frequency oscillation (10³ Hz to a few hundred Hz) rather than minor voltage oscillations. This periodic current modulation at optimized frequencies simultaneously improves storage performance and reduces charging time at low temperatures by matching the battery's impedance characteristics.
Solution Approach 2:
The patent employs parameter changes by adjusting both the frequency and amplitude parameters of the charge current based on temperature conditions. This dynamic parameter adjustment optimizes the balance between storage performance and charging speed, unlike fixed constant voltage charging with minor oscillations.
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 reduces charging time and battery degradation, improves battery life, and increases autonomy by optimizing the charging process, especially at low temperatures, while maintaining equivalent mean current or power degradation compared to continuous charging.
Implementation Method 1
determining the electrolyte resistance frequency of the battery, determining the charge transfer resistance frequency of the battery
Data Source
AI summary
A method for charging a motor vehicle battery includes determining the electrolyte resistance frequency of the cell, determining the battery charge transfer resistance frequency, and charging the battery with a current at a charging current frequency greater than the electrolyte resistance frequency of the battery and less than the battery charge transfer resistance frequency.