Negative Electrode Sheet Insulation Coating for Swelling Isolation
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Solution Overview
Problem
The swelling of negative electrode sheets in batteries can cause them to puncture the separator and directly contact the positive electrode sheet, leading to short circuits, fires, or explosions due to the change in volume.
Innovation Solution
An insulation coating layer is applied to the non-tab area of the electrode sheet to prevent direct contact and short circuits by providing insulating protection, even when the electrode sheet swells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode sheet is used without insulation coating, then the battery structure is simple and manufacturing cost is low, but the negative electrode sheet may swell and puncture the separator causing short circuit
Solution Approach 1:
An insulation coating layer is introduced as an intermediary substance between the negative electrode sheet and the separator. This coating layer prevents direct contact between the swollen negative electrode and the separator, thereby avoiding short circuits while maintaining the overall battery structure.
Solution Approach 2:
A thin film insulation coating is applied to the surface of the negative electrode sheet. This flexible thin film follows the swelling of the electrode while providing continuous insulation protection, preventing the electrode from puncturing the separator during volume expansion.
2Reliability
If an insulation coating layer is added to the electrode sheet, then short circuit prevention is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The insulation coating process is merged with the existing electrode sheet manufacturing process. The coating is applied during the same production line operations, combining multiple functions (insulation and current collection) into a single integrated manufacturing step, thereby minimizing additional process complexity.
Solution Approach 2:
The surface properties of the electrode sheet are modified by changing the chemical or physical parameters of the coating layer. This allows the electrode to maintain its electrical functionality while acquiring insulation properties through parameter modification rather than adding separate components.
3Quantity of substance
If the negative electrode sheet swells during operation, then the battery capacity increases, but the electrode may contact the positive electrode causing fire or explosion
Solution Approach 1:
The insulation coating layer serves as a pre-established protective barrier that cushions against the harmful effects of electrode swelling. Before any short circuit or thermal runaway can occur, the coating prevents direct contact between electrodes, thereby cushioning the system against these catastrophic failures during capacity expansion.
Data Source
AI summary
Disclosed are an electrode sheet, a negative electrode sheet, an electrode assembly, and a lithium ion battery. The negative electrode sheet includes: a negative current collector, including a negative coating area, as well as a negative electrode tab and a non-tab area disposed at opposite ends of the negative coating area; and one or more negative active material layers disposed on the negative coating area. An insulation coating layer is disposed on the non-tab area.