Battery Charging Protocols Using Internal Resistance Profiles
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Solution Overview
Problem
Existing methods for deriving charging protocols for large capacity battery cells are cumbersome and require manufacturing three-electrode cells, which are difficult to produce and lack consideration for internal resistance and heat generation during quick charging, leading to potential battery failure and inefficiencies.
Innovation Solution
A battery management system that measures closed and open circuit voltages to calculate internal resistance values, determining limit states of charge from internal resistance profiles without requiring a three-electrode cell, and updates charging protocols to reflect battery aging and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-electrode cell is used to derive charging protocols, then the limit state of charge can be established, but the manufacturing complexity and time increase significantly
Solution Approach 1:
The patent extracts the essential measurement function from the complex three-electrode cell system and implements it using only two electrodes. The third electrode's potential measurement function is replaced by calculating internal resistance from voltage and current measurements in the two-electrode system, thereby eliminating the manufacturing complexity while preserving the ability to determine the limit state of charge
Solution Approach 2:
The patent creates a simplified model that copies the essential functionality of the three-electrode cell approach. Instead of physically manufacturing three-electrode cells, the system uses two-electrode measurements combined with internal resistance calculations to replicate the charge limit determination capability, avoiding the need for dedicated charger/discharger equipment
2Productivity
If conventional charging protocols are used without considering internal resistance, then charging can proceed quickly, but battery aging and failure risk increase
Solution Approach 1:
The patent implements a feedback mechanism where internal resistance is continuously measured during charging cycles. The charging protocol is dynamically adjusted based on the measured internal resistance values and their rate of change. When the internal resistance change rate exceeds a threshold, the system automatically reduces charging current or terminates charging, preventing battery damage while enabling faster safe charging rates
Solution Approach 2:
The charging protocol transitions from a static, fixed-current approach to a dynamic approach where charging parameters are continuously adjusted based on real-time internal resistance measurements. The system adapts the charging current profile during the charging process to optimize both speed and safety, allowing higher currents when resistance is stable and reducing currents when resistance changes rapidly
3Loss of time
If high charging current is applied to achieve quick charging, then charging time is reduced, but heat generation and battery aging increase
Solution Approach 1:
The system uses real-time monitoring of internal resistance changes as a feedback indicator of heat generation and battery stress. When rapid charging causes excessive heat, the internal resistance changes at an accelerated rate, which the system detects and responds to by reducing charging current, thereby controlling temperature while minimizing charging time
Solution Approach 2:
The patent changes the charging current parameter dynamically based on internal resistance measurements. Instead of applying constant high current, the system adjusts current magnitude according to the battery's real-time condition, enabling high-current fast charging when safe and reducing current when heat generation becomes excessive
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
Enables quick charging protocols that reflect battery resistance and heat generation, non-destructively identifying battery degradation and updating charging strategies to maintain efficiency and safety.
Implementation Method 1
an internal resistance value according to a state of charge by substituting the measured closed circuit voltage and open circuit voltage into a predetermined equation
Data Source
AI summary
A charging protocol establishment method and battery management system of a lithium secondary battery are provided, wherein, for a two-electrode battery cell, a closed-circuit voltage (CCVSOCx) and an open-circuit voltage (OCVSOCx) according to a state of charge (SOCx) during charging with each charging current (I) are measured according to Equation 1 below, and by collecting internal resistance profiles plotting the internal resistance value (RSOCx) according to the state of charge for each charge current (I), limit state of charges corresponding to each charge current are determined from the internal resistance profiles.Internal resistance value according tostate of charge (RSOCx)=(CCVSOCx-OCVSOCx)/IEquation 1