Positive Electrode CNT Gradient for Lower Short-Circuit Heat
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries with carbon nanotubes in the positive electrode mixture layer enhance electron conductivity and battery capacity but increase heat generation during internal short circuits, necessitating a balance to suppress heat generation while maintaining capacity and output.
Innovation Solution
A positive electrode with a conductive agent containing carbon nanotubes, where the mass ratio of carbon nanotubes to active material is higher in the lower half region near the current collector and lower in the upper half region, optimizing electron conductivity and reducing heat generation during internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If carbon nanotubes are added to the positive electrode mixture layer to enhance electron conductivity and improve battery capacity or output, then heat generation during internal short circuit increases
Solution Approach 1:
The patent applies local quality by creating a positive electrode mixture layer with non-uniform carbon nanotube distribution. The concentration of carbon nanotubes varies through the thickness of the layer, with higher concentration near the current collector and lower concentration toward the outer surface. This localized variation optimizes electron conductivity where needed while reducing heat generation in regions prone to short circuits.
Solution Approach 2:
The patent segments the positive electrode mixture layer into multiple regions with different carbon nanotube concentrations. By dividing the layer into zones (e.g., first region near current collector, second region in middle, third region at surface) with progressively decreasing carbon nanotube content, the design addresses both conductivity requirements and heat generation concerns in different spatial locations.
2Object-generated harmful factors
If the amount of carbon nanotubes is reduced to suppress heat generation during internal short circuit, then battery capacity or output decreases
Solution Approach 1:
Rather than uniformly reducing carbon nanotube content throughout the electrode, the patent applies local quality by maintaining higher carbon nanotube concentration in specific regions (near the current collector) where conductivity is critical, while reducing concentration in other regions (toward the surface) where heat generation during short circuits is more problematic. This selective distribution preserves battery output while suppressing harmful heat generation.
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
This configuration effectively suppresses heat generation during internal short circuits while maintaining battery capacity and output, compared to uniform carbon nanotube distribution or reduced carbon nanotube amounts.
Implementation Method 1
By adding the carbon nanotubes to the positive electrode mixture layer, electron conductivity of the positive electrode mixture layer can be enhanced
Implementation Method 2
heat generation of the battery during an internal short circuit is increased
Data Source
AI summary
A non-aqueous electrolyte secondary battery positive electrode that is characterized by comprising a positive electrode collector and a positive electrode mixture layer that is provided on the positive electrode collector and includes a positive electrode active material and a conductive material that includes carbon nanotubes. The non-aqueous electrolyte secondary battery positive electrode is also characterized in that, when the positive electrode mixture layer is bisected in the thickness direction, the mass ratio of carbon nanotubes to positive electrode active material in an upper-half region that is on a top surface side is smaller than the mass ratio of carbon nanotubes to positive electrode active material in a lower-half region that is on the positive electrode collector side.