Non-aqueous Battery SEI Layer Formation via Staged Charging
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Solution Overview
Problem
Existing methods for forming a solid electrolyte interface (SEI) layer in non-aqueous electrolyte secondary batteries face challenges in achieving high accuracy and efficiency due to simultaneous decomposition of multiple precursors during the initial charging step, leading to overvoltage and decreased production efficiency.
Innovation Solution
A manufacturing method that involves stopping charging after reaching a first specified voltage to form a first layer and then charging to a second specified voltage to form a second layer, allowing for precise formation of each layer without simultaneous decomposition, thereby mitigating overvoltage and improving production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If charging is performed continuously to form multiple layers during initial charging, then the SEI layer formation is completed, but multiple precursors decompose simultaneously causing overvoltage and reduced production efficiency
Solution Approach 1:
The patent divides the SEI layer formation process into distinct stages by stopping charging at intermediate voltages (e.g., stopping at 4.2V before reaching the final 4.35V). This segmentation prevents simultaneous decomposition of multiple precursors, allowing controlled formation of different SEI layers at different voltage ranges, thereby maintaining manufacturing precision while avoiding overvoltage issues that would reduce productivity
Solution Approach 2:
The patent performs preliminary charging stops at specific voltage points during the initial charging process. By pausing charging at intermediate voltages (preliminary actions), the system allows the first SEI layer to form completely before proceeding to form the second SEI layer at higher voltages. This preliminary action prevents simultaneous precursor decomposition and overvoltage, ensuring both precise layer formation and efficient production
2Manufacturing precision
If charging is stopped to form the first layer before forming the second layer, then each layer is formed with high accuracy, but the initial charging time increases
Solution Approach 1:
The patent applies partial action by stopping charging at intermediate voltage points (e.g., 4.2V) during the initial charging process, rather than continuously charging to the final voltage (4.35V). This partial charging approach allows the first SEI layer to form with high accuracy before the second layer formation begins, preventing simultaneous precursor decomposition while minimizing the total time loss compared to more extensive stopping procedures
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 method enables the formation of a high-output non-aqueous electrolyte secondary battery with a suitable SEI layer, enhancing output characteristics while maintaining high production efficiency by preventing simultaneous decomposition of precursors.
Implementation Method 1
a battery assembly in which an electrode body and a non-aqueous electrolyte are accommodated in a battery case is prepared, and then an initial charging step (conditioning) is performed for the battery assembly. Thus, power generation elements (electrode body and non-aqueous electrolyte) are activated
Implementation Method 2
When the initial charging step is performed, a part of a solvent of the non-aqueous electrolyte is decomposed, and a solid electrolyte interface (SEI) layer is formed on the surface of the electrode
Data Source
AI summary
A manufacturing method for a non-aqueous electrolyte secondary battery includes preparing a battery assembly, and performing an initial charging on the battery assembly. In the initial charging, a differential capacity curve of the battery assembly has a first peak voltage at which a first layer is formed on the electrode body and a second peak voltage at which a second layer is formed on the electrode body. The initial charging includes forming the first layer by stopping charging for a first stop time after charging to a first specified voltage that is set between the first peak voltage and the second peak voltage, and forming a second layer with charging performed to a second specified voltage that is set higher than the second peak voltage after forming the first layer.