Electrode Plate Safety Coating for Thermal Runaway Prevention
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Solution Overview
Problem
Lithium-ion batteries face safety hazards due to internal short circuits, which existing modifications to incorporate PTC materials into the electrode active material layer or as a separate safety coating either compromise electrochemical performance or fail to effectively prevent overheating and explosions.
Innovation Solution
An electrode plate design featuring a current collector, an electrode active material layer, and a safety coating with a fluorinated polyolefin or chlorinated polyolefin polymer matrix, conductive material, and inorganic filler, where the polymer matrix functions as both a binder and PTC matrix, enhancing the safety coating's adhesion and response speed while preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTC materials are added to the electrode active material layer, then safety performance is improved, but electrochemical performance deteriorates
Solution Approach 1:
The patent divides the electrode structure into distinct functional layers: a current collector, an electrode active material layer, and a separate safety coating layer. This segmentation allows the PTC material to be isolated in the safety coating layer, preventing it from interfering with the electrochemical reactions in the active material layer while still providing safety protection through thermal runaway prevention.
2Reliability
If a separate PTC material layer is placed between the current collector and electrode active material layer, then safety effect is achieved, but the PTC layer is dissolved by solvent and electrical properties deteriorate
Solution Approach 1:
The patent employs a composite material structure for the safety coating layer, combining PTC material with binder materials and conductive additives. This composite formulation enhances the chemical stability of the PTC layer against solvent dissolution while maintaining its positive temperature coefficient properties. The binder and conductive additives work together to preserve the layer's structural integrity and electrical functionality during battery operation.
3Reliability
If PTC material layer is used, then safety performance is improved, but the layer is squeezed to the edge during compacting and current collector directly contacts active material layer
Solution Approach 1:
The patent applies the safety coating layer to the current collector surface before the electrode active material layer is formed. This preliminary positioning ensures that the PTC layer is firmly established in its protective role. Additionally, the use of binder materials in the coating provides adhesive strength that prevents the layer from shifting or being squeezed to the edges during subsequent compacting operations, maintaining proper layer alignment and preventing direct contact between the current collector and active material layer.
4Reliability
If PTC material is added to improve response speed and current blocking effect, then safety performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the composition parameters of the safety coating layer, specifically controlling the ratios of PTC material, binder, and conductive additives. By adjusting these parameters, the coating achieves rapid thermal response and effective current blocking properties. The formulation is designed to be compatible with existing coating and drying processes, allowing the safety layer to be integrated into current manufacturing workflows without requiring entirely new equipment or complex multi-step procedures.
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 improves the safety and electrical performance of lithium-ion batteries by effectively preventing overheating and internal short circuits, maintaining electrochemical performance, and facilitating mass production with enhanced cycle life and safety features.
Implementation Method 1
A PTC (Positive Temperature Coefficient) material is a positive temperature coefficient heat sensitive material, which has the characteristic that its resistivity increases with increasing temperature. When the temperature exceeds a certain temperature, its resistivity increases rapidly stepwise.
Implementation Method 2
the polymer matrix functions as both a binder and PTC matrix, enhancing the safety coating's adhesion and response speed
Data Source
AI summary
The present invention relates to an electrode plate, an electrochemical device and a safety coating. The electrode plate comprises a current collector, an electrode active material layer and a safety coating disposed between the current collector and the electrode active material layer, the safety coating layer comprising a fluorinated polyolefin and/or chlorinated polyolefin polymer matrix, a conductive material and an inorganic filler. The electrode plate can quickly open the circuit when the electrochemical device (for example, a capacitor, a primary battery, or a secondary battery) is in a high temperature condition or an internal short circuit occurs, and thus it may improve the high temperature safety performance of the electrochemical device.