Battery Charging Control Using Differential Capacity Peaks
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Solution Overview
Problem
Batteries experience accelerated degradation due to over-potential during charging, leading to lithium metal deposition and internal short circuits, which existing technologies fail to adequately address.
Innovation Solution
A battery management system that updates over-potential management information based on previous cycle constant-current charging events, using voltage and current sensors to adjust charging conditions, including reference peak values and ratios to prevent excessive polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high charging current is used to increase charging speed, then productivity is improved, but over-potential increases causing battery degradation and lithium deposition
Solution Approach 1:
The charging current is dynamically adjusted based on real-time monitoring of differential capacity curves. The system transitions from static fixed-current charging to dynamic current modulation, reducing current when polarization indicators are detected and restoring it when safe, thereby preventing over-potential while maintaining high average charging speed
Solution Approach 2:
The system implements feedback control by continuously monitoring voltage and current during charging, calculating differential capacity curves, and using these measurements to adjust charging parameters. This closed-loop feedback mechanism detects early signs of over-potential and automatically corrects charging conditions to prevent battery degradation
2Loss of time
If constant high current charging is applied, then charging time is reduced, but polarization becomes severe leading to accelerated battery degradation
Solution Approach 1:
The system applies periodic modulation to the charging current based on detected polarization levels. When differential capacity curves indicate severe polarization, the current is temporarily reduced or pulsed off, then restored when polarization subsides. This periodic action prevents cumulative over-potential while maintaining overall charging efficiency
Solution Approach 2:
The system changes charging parameters (current magnitude, pulse duration, rest intervals) based on real-time battery state assessment through differential capacity analysis. By dynamically adjusting these parameters rather than maintaining constant current, the system minimizes polarization effects while optimizing charging time
3Productivity
If charging continues without monitoring over-potential, then productivity is maximized, but lithium metal deposition occurs causing internal short circuits
Solution Approach 1:
The system performs preliminary detection of polarization trends using differential capacity curves before over-potential reaches dangerous levels. By identifying early warning signs in the voltage-current characteristics, the system takes preventive action to adjust charging parameters, avoiding lithium deposition entirely rather than reacting after damage occurs
Solution Approach 2:
The differential capacity curve serves as an intermediary indicator that mediates between charging current and battery state. Instead of directly monitoring difficult-to-measure over-potential or lithium deposition, the system uses the easily measurable differential capacity curve as an intermediate signal to infer and control the risk of harmful effects
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
Prevents lithium deposition and protects batteries from excessive over-potential by optimizing charging conditions, thereby extending battery life and safety.
Implementation Method 1
a voltage sensor configured to generate a voltage sensing signal indicating a voltage of a battery
Implementation Method 2
a current sensor configured to generate a current sensing signal indicating a current of a battery
Implementation Method 3
lithium batteries have little or no memory effect, and thus they are gaining more attention than nickel-based batteries for their advantages that recharging can be done whenever it is convenient
Implementation Method 4
While a battery is being charged, polarization occurs in the battery. The polarization depends on a plurality of resistance components (for example, Ohm resistance, electric charge transfer, diffusion resistance) of the battery
Implementation Method 5
when the voltage of the negative electrode of the battery drops below 0 V due to the over-potential, lithium metal deposition rapidly occurs on the negative electrode surface
Data Source
AI summary
A battery management system includes a sensor to sense voltage and current of a battery, memory to store over-potential management information including reference peak and reference peak voltage values, and a controller to command constant-current charging using a maximum allowable C-rate to a charging circuit when the reference peak value is equal to or larger than a threshold peak value, in response to a charge request, determine a differential capacity curve indicating a correlation between the voltage and differential capacity of the battery within a range based on the sensed voltage and current during the charging, determine main peak and main peak voltage values indicating differential capacity and voltage of a peak of the differential capacity curve, respectively, and update the reference peak and reference peak voltage values to equal the main peak and main peak voltage values, when the main peak value is less than the threshold peak value.