Lithium Battery Electrode Functional Layer for Thermal Runaway Prevention
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Solution Overview
Problem
Lithium secondary batteries face instability issues due to internal short circuits, overcharge, and heat runaway, leading to potential explosions, which can cause damage and safety risks.
Innovation Solution
Incorporating a functional layer with polymer particles of specific weight-average molecular weight (200 to 50,000) and average particle size (0.3 μm to 2.3 μm) between the current collector and active material layers in the electrodes, which acts as an insulation layer to prevent further reactions and explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a functional layer with polymer particles is added to prevent internal short circuits and improve stability, then battery stability and safety are improved, but device complexity increases due to additional layers
Solution Approach 1:
The electrode is segmented into multiple functional layers: current collector layer, functional layer with polymer particles, and active material layer. This segmentation allows each layer to perform its specific function - the functional layer with polymer particles specifically addresses internal short circuit prevention while maintaining overall electrode functionality.
Solution Approach 2:
The functional layer containing polymer particles acts as an intermediary layer between the current collector and active material. This intermediate layer prevents direct contact between electrodes that could cause internal short circuits, while still allowing ionic transport through the polymer matrix.
2Object-affected harmful factors
If the functional layer with polymer particles is used to prevent heat runaway and explosions, then safety is improved, but manufacturing precision requirements increase due to specific molecular weight and particle size specifications
Solution Approach 1:
Specific parameters of the polymer particles are defined to optimize safety performance: weight-average molecular weight of 200 to 50,000 and average particle size of 0.3 μm to 2.3 μm. These parameter specifications ensure the polymer particles can effectively prevent heat runaway while maintaining manufacturability within reasonable precision limits.
Solution Approach 2:
The polymer particles in the functional layer undergo phase transitions at specific temperatures to prevent heat runaway. The controlled molecular weight and particle size enable the polymer to melt or decompose at appropriate temperatures, creating a physical barrier that stops thermal propagation between electrodes.
3Productivity
If polymer particles with specific molecular weight range are used in the functional layer, then charge and discharge characteristics are improved, but material selection complexity increases
Solution Approach 1:
The weight-average molecular weight of polymer particles is controlled within a specific range (200 to 50,000) to optimize charge and discharge characteristics. This parameter control ensures adequate ionic conductivity while maintaining structural integrity of the functional layer during battery operation.
Solution Approach 2:
The functional layer uses composite material composition combining polymer particles with specific molecular weight characteristics. This composite approach allows optimization of multiple properties - ionic conductivity, mechanical strength, and thermal stability - through careful selection of polymer materials within the specified molecular weight range.
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 significantly improves the stability and charge/discharge characteristics of lithium secondary batteries by preventing internal temperature increases and subsequent explosions, while maintaining excellent battery performance.
Implementation Method 1
the functional layer includes a polymer particle having a weight-average molecular weight of 200 to 50,000... acts as an insulation layer to prevent further reactions and explosions
Data Source
AI summary
The present disclosure relates to an electrode for a lithium secondary battery, the electrode comprising: a current collector layer; a functional layer disposed on the current collector layer; and an active material layer disposed on the functional layer, wherein the functional layer includes a polymer particle having a weight-average molecular weight of 200 to 50,000.