Positive Electrode Binding Layer for Nail Penetration Safety
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Solution Overview
Problem
Lithium-ion batteries face safety hazards due to puncture and nail penetration, leading to potential fires and explosions, and existing solutions do not effectively address these issues.
Innovation Solution
A positive electrode plate with a binding layer composed of a polymer material, conductive material, and inorganic filler, where the polymer material is oil-dispersible and has reduced solubility in NMP, enhancing ductility and stability to prevent cracking and internal resistance deterioration, and the inorganic filler improves safety performance by stabilizing the binding layer and preventing direct contact between the current collector and active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional polymer material (e.g., PVDF) is used in the binding layer, then good binding performance is achieved, but the binding layer is prone to cracking and internal resistance deterioration under abnormal conditions
Solution Approach 1:
The patent uses a composite polymer material consisting of PVDF and polyacrylonitrile (PAN) in a specific weight ratio (30-70 wt% PVDF, 30-70 wt% PAN). This composite combines the good binding performance of PVDF with the high ductility and crack resistance of PAN, creating a binding layer that maintains integrity under puncture conditions while preventing cracking and internal resistance deterioration.
Solution Approach 2:
The patent optimizes the compositional parameters of the polymer material by controlling the weight ratio of PVDF to PAN within specific ranges. This parameter optimization balances the competing requirements of binding performance and crack resistance, allowing the binding layer to achieve both reliability under puncture and resistance to cracking.
2Reliability
If the binding layer is made more ductile to prevent cracking, then safety performance improves, but electrical performance may deteriorate
Solution Approach 1:
The PVDF-PAN composite polymer material provides a balanced property profile where PAN contributes ductility for safety while PVDF maintains good electrical characteristics. The specific weight ratio optimization ensures that the composite achieves sufficient ductility for puncture resistance without excessive polymer content that would harm electrical performance.
Solution Approach 2:
The binding layer is designed with specific local composition characteristics by controlling the polymer blend ratio. This allows different regions of the binding layer to exhibit appropriate properties: sufficient ductility for safety at the macro level, while maintaining adequate electrical conductivity through optimized material composition.
3Reliability
If the binding layer provides strong protection during puncture, then safety performance improves, but manufacturing complexity increases
Solution Approach 1:
While using a composite polymer material does increase material complexity, the patent simplifies the overall system by integrating multiple functions into a single binding layer component. The PVDF-PAN composite simultaneously provides binding, ductility, crack resistance, and adequate electrical performance, eliminating the need for multiple separate layers or complex structural designs.
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 proposed electrode plate design significantly enhances safety and electrical performance, particularly during nail penetration, by preventing cracking and internal resistance issues, while maintaining effective electrochemical performance and reducing the risk of battery failure.
Implementation Method 1
having a solubility in NMP at 130 °C for 5 minutes, which is 30% or less of the solubility of PVDF under the same conditions
Data Source
Figure 1
AI summary
The present invention relates to a positive electrode plate and an electrochemical device. The positive electrode plate includes a current collector (10), a positive active material layer (14), and a binding layer (12) disposed between the current collector (10) and the positive active material layer (14), the binding layer (12) comprising a polymer material, a conductive material, and an inorganic filler, wherein the polymer material comprises a binding layer matrix and the binding layer matrix is an oil-dispersible polymer material having a solubility in NMP at 130 °C for 5 minutes, which is 30% or less of the solubility of PVDF under the same conditions. The positive electrode plate can improve the safety performance of the electrochemical device (for example, a capacitor, a primary battery, a secondary battery, or the like) under abnormal conditions such as nailing penetration.