Folded Separator Electrode Assembly for Low-Gap Fast-Charging Cells
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Solution Overview
Problem
The stack and folding type electrode assembly for lithium secondary batteries experiences lithium ion precipitation due to a space between the electrode and the separator, which affects the battery's life characteristics and rapid charging performance.
Innovation Solution
A method involving the application of a binder composition on the folding separator's surface opposite to the unit cells, followed by heating and pressing to fix the unit cells and fill the space between the electrode and the separator, ensuring a stable interface and minimizing lithium ion diffusion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stack and folding type electrode assembly is prepared by simply contacting the folding separator and electrode without compression, then the preparation process is simple, but a space is formed between the electrode and separator causing lithium ion precipitation
Solution Approach 1:
The patent applies binder composition to the folding separator surface in advance before stacking the electrode assembly. This preliminary action ensures that when the electrode and separator are stacked, the binder composition is already positioned to fill any potential spaces, preventing lithium ion precipitation without requiring additional compression steps.
Solution Approach 2:
The binder composition acts as an intermediary substance between the folding separator and the electrode. It fills the space formed at the interface, enabling smooth lithium ion diffusion while maintaining the simple stacking preparation process. The binder composition mediates the interaction between the separator and electrode to eliminate the harmful space.
2Reliability
If heating and pressing is applied to compress the gap between electrode and separator, then lithium ion diffusion is improved, but the preparation process complexity increases
Solution Approach 1:
The patent extracts the compression step from the preparation process by using binder composition that naturally fills spaces during simple stacking. The binder composition takes out the need for mechanical compression, achieving the same effect of eliminating spaces without adding process complexity.
3Reliability
If binder composition is applied to the folding separator surface before stacking, then space filling and lithium ion diffusion are improved, but the preparation process steps increase
Solution Approach 1:
The patent merges the binder application step with the separator preparation step. By applying binder composition to the folding separator surface before stacking, these two operations are combined into a seamless process flow, adding minimal steps while achieving superior lithium ion diffusion performance.
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 effectively reduces lithium ion precipitation, enhancing the long-term life characteristics and rapid charging performance of the secondary battery by ensuring a consistent and efficient lithium ion diffusion process.
Implementation Method 1
heating and pressing to fix the unit cells and fill the space between the electrode and the separator
Implementation Method 2
heating and pressing to fix the unit cells and fill the space between the electrode and the separator
Data Source
AI summary
The present disclosure relates to a method of preparing an electrode assembly capable of improving life characteristics and rapid charging performance by minimizing a space between a folding separator and an electrode. The method of preparing the electrode assembly includes disposing a plurality of unit cells on a first surface of a folding separator, fixing the unit cells on the first surface of the folding separator, providing a binder composition to at least one end portion of a second surface of the folding separator, and stacking the unit cells by folding the folding separator.