Insulating Layer Composition for Lithium Battery Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing separators in lithium secondary batteries have insufficient thermal resistance, leading to internal short circuits and thermal runaway due to dendritic growth or external damage, and the conventional insulation methods, such as using polyimide film tapes, are complex and prone to unwinding.
Innovation Solution
A composition for forming an insulating layer using a binder polymer, organic dye or oil-soluble dye as a coloring agent, and a solvent with high viscosity, which allows for easy alignment and adhesion to the electrode active material layer, preventing erosion and enhancing cohesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microporous film separator with thermal resistance temperature of 120 to 160°C is used, then the battery can maintain normal operation, but the separator shrinks due to short-circuit reaction heat causing thermal runaway
Solution Approach 1:
The patent applies beforehand cushioning by pre-coating the separator with a heat-resistant material (such as aluminum oxide, silicon oxide, or titanium oxide) before the separator is exposed to high temperatures during short-circuit conditions. This pre-applied coating acts as a thermal barrier that prevents the separator film from shrinking and causes short-circuit reaction heat to be released externally rather than causing thermal runaway internally.
2Reliability
If polyimide film tape is wound around the electrode tab for insulation, then short circuit prevention is achieved, but the process becomes complex and the tape may unwind
Solution Approach 1:
The patent extracts the insulation function from a separate polyimide film tape and integrates it directly into the separator structure by coating the separator surface with an insulating material. This eliminates the need for separate tape winding operations and associated complexity while maintaining the insulation function.
Solution Approach 2:
The patent merges the insulation function with the separator structure itself by coating the separator with insulating material. This combines two previously separate components (separator and insulation layer) into a single integrated structure, eliminating the need for separate insulation tapes and their complex installation processes.
3Reliability
If insulation tape is wound from the upper portion of the current collector downward, then insulation coverage is improved, but the electrode assembly thickness increases
Solution Approach 1:
The patent merges the insulation layer with the separator structure, allowing the insulation to be provided as a coating on the separator surface rather than as a separate thick tape layer. This integration maintains insulation coverage while minimizing additional thickness.
Solution Approach 2:
The patent uses a thin film coating approach rather than thick tape winding. The insulating material is applied as a thin coating layer on the separator surface, providing sufficient insulation coverage without significantly increasing the electrode assembly thickness.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a composition for forming an insulating layer for a lithium secondary battery, which includes a binder polymer; a coloring agent including at least one selected from the group consisting of an organic dye, an oil-soluble dye and an organic phosphor; and a solvent, and has a viscosity of 1,000 cP or more at 25 °C.