Battery Cell Formation Monitoring Using In-Process Impedance Feedback
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Solution Overview
Problem
Existing methods for monitoring and controlling the formation process of battery cells, particularly lithium-ion batteries, fail to account for individual cell variations, leading to unsuitable potential development at interfaces and inefficient process profiles, which can negatively affect the formation of a well-defined solid electrolyte interface (SEI) and increase production costs.
Innovation Solution
A method utilizing electrochemical impedance spectroscopy (EIS) to monitor the formation process by generating an equivalent circuit diagram, determining parameters like ohmic resistance and capacitance of the SEI, and adjusting current or voltage profiles based on these parameters to optimize the formation process for each cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If empirical tests and fixed process parameters are used for formation, then the process is simple to control, but individual cell variations cannot be accounted for, leading to suboptimal SEI formation and increased production costs
Solution Approach 1:
The patent implements real-time feedback by continuously measuring impedance during the formation process and using this information to adjust process parameters. The system monitors the battery cell's impedance characteristics and feeds this information back to the control system, which then modifies current or voltage profiles to optimize SEI formation for each individual cell, resolving the contradiction between precision and complexity.
Solution Approach 2:
The system enables the battery cell to effectively monitor its own formation state through impedance measurements. By measuring the cell's own impedance characteristics during formation, the system allows each cell to provide information about its own state, which is then used to adjust the formation process parameters specifically for that cell, improving SEI formation quality without requiring complex external intervention.
2Productivity
If fixed current and voltage profiles are applied to all cells, then the process is efficient and cost-effective, but individual cell variations lead to unsuitable potentials at interfaces, negatively affecting SEI formation
Solution Approach 1:
The patent transitions from static, fixed formation profiles to dynamic, adaptive profiles. The system continuously adjusts current and voltage parameters during the formation process based on real-time impedance measurements. This dynamic adjustment allows the formation process to adapt to individual cell variations while maintaining overall efficiency, as the system only modifies parameters when and where needed rather than applying complex sequences to all cells.
Solution Approach 2:
The system changes process parameters (current, voltage, time) based on measured impedance characteristics. By monitoring impedance and adjusting formation parameters accordingly, the system optimizes SEI formation for each cell's specific characteristics. This parameter adaptation maintains productivity by avoiding completely re-engineered formation sequences while improving precision through targeted adjustments.
3Measurement precision
If impedance measurements and equivalent circuit modeling are implemented for each cell, then individual cell monitoring is achieved, but the device complexity and measurement requirements increase
Solution Approach 1:
The patent makes the formation device multi-functional by integrating both formation (charging/discharging) and measurement (impedance spectroscopy) capabilities into a single system. The same hardware infrastructure used for applying formation currents is also used for measuring impedance, eliminating the need for separate dedicated measurement equipment. This universal approach reduces overall device complexity while maintaining high measurement precision.
Solution Approach 2:
The system merges the formation process and measurement process into a unified operation. Impedance measurements are performed during the formation process itself rather than as separate steps, combining two functions into one integrated workflow. This merging reduces the number of separate devices and operations needed, lowering complexity while maintaining accurate cell-state monitoring throughout formation.
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 allows for a more efficient and controlled formation process, ensuring the quality of the SEI while minimizing energy and time consumption, thereby improving the production efficiency and reducing costs.
Implementation Method 1
At least one impedance measurement is performed during the formation process using a sensing device of the formation device. An equivalent circuit diagram of the battery cell during the formation process is generated using an electronic computing device of the formation device.
Data Source
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AI summary
The invention relates to a method for monitoring a formation process of a battery cell (14) by means of a formation device (10), comprising the steps of: charging the battery cell (14) with at least one first formation current (26) by means of a charging device (16) of the formation device (10); performing at least one impedance measurement (32) during the formation process by means of a detection device (18) of the formation device (10); specifying an equivalent circuit diagram of the battery cell (14) in the formation process by means of an electronic computing device (20) of the formation device (10); determining at least one parameter (30) of the equivalent circuit diagram as a function of the impedance measurement (32) performed by means of the electronic computing device (20); and monitoring the formation process as a function of the determined at least one parameter (30) by means of the electronic computing device (20).Furthermore, the invention relates to a computer program product, a computer-readable storage medium and an electronic computing device (20).