Protective Electrode Sheet Coating for Internal Short-Circuit Safety
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to internal short circuits leading to thermal runaway and explosions, with no mature solution to effectively prevent these events.
Innovation Solution
An electrode sheet with a current collector having a coated and uncoated region, where the uncoated region is covered with a protective layer of low conductivity (0 S/m to 3.5×10^7 S/m) made from inorganic oxides, high molecular polymers, or non-metallic substances, which increases contact resistance and reduces thermal runaway probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery cell uses a conventional current collector without protective layer, then the manufacturing process is simple and production efficiency is high, but the internal short circuit can cause severe thermal runaway and explosion
Solution Approach 1:
The protective layer is pre-applied to the uncoated region of the current collector before battery assembly. This preliminary protective measure ensures that if an internal short circuit occurs, the protective layer is already in place to increase contact resistance and prevent thermal runaway, eliminating the need for complex active safety systems.
Solution Approach 2:
The protective layer acts as an intermediary substance between the current collector and any potential short circuit points. When a short circuit occurs, this intermediate layer increases the contact resistance, disrupting the direct conductive path and preventing severe thermal runaway while maintaining the overall simplicity of the battery structure.
2Reliability
If the protective layer is applied to the uncoated region of the current collector, then the contact resistance increases and thermal runaway probability decreases, but the manufacturing process becomes more complex
Solution Approach 1:
The protective layer is applied selectively only to the uncoated region of the current collector, not the entire surface. This local application approach provides the necessary safety function where it is most needed (at the edges and uncoated areas most prone to short circuits) while minimizing the impact on manufacturing complexity and material usage.
3Reliability
If the protective layer has low conductivity (0 S/m to 3.5×10^7 S/m), then the discharge power during short circuit is reduced and safety improves, but the material selection and quality control become more difficult
Solution Approach 1:
The patent specifies a broad conductivity range (0 S/m to 3.5×10^7 S/m) for the protective layer, allowing flexibility in material selection and manufacturing tolerances. This parameter specification ensures that the protective layer effectively increases contact resistance during short circuits while providing a practical range for manufacturing control and quality assurance.
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
The solution enhances safety performance by reducing discharge power and thermal runaway risk during internal short circuits, improving the overall safety of the battery cell.
Implementation Method 1
the contact resistance of the electrode sheet may be increased when this battery cell is internally short-circuited
Data Source
AI summary
The present application relates to an electrode sheet, a battery cell and a battery. The electrode sheet includes a current collector and a protective layer. The current collector includes a coated region provided with an active material layer and an uncoated region without being provided with the active material layer. The protective layer is provided on at least a part of a surface of the uncoated region, and has a porosity of 0% to 95%. For the electrode sheet according to the present application, by providing the current collector with the protective layer, the contact resistance may be increased when the electrode sheet is short-circuited, and the discharge power and the thermal runaway probability of the battery cell may be reduced when the battery cell is internally short-circuited, thereby improving the safety performance of the battery cell.