Partially Exfoliated Graphite Composite Electrode for High-Current Heat Suppression
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Solution Overview
Problem
Existing electricity storage devices, such as secondary batteries, generate excessive heat during large current charge and discharge cycles due to high resistance at the positive electrode, leading to thermal runaway, which is not adequately suppressed by current electroconductive agents like flake graphite.
Innovation Solution
The use of a composite electrode material comprising partially exfoliated graphite as the first carbon material and another carbon material, such as graphene or carbon black, in a specific weight ratio, enhances electroconductivity and reduces resistance, thereby suppressing heat generation during high-current operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flake graphite is used as an electroconductive agent, then the electrode structure is simple and easy to manufacture, but the specific surface area is small resulting in few contact points with the positive electrode active material and insufficient resistance reduction
Solution Approach 1:
The patent uses a composite of two different carbon materials (first carbon material with graphite structure and second carbon material) to combine the advantages of both materials. The first carbon material provides structural stability and electroconductivity, while the second carbon material increases specific surface area and contact points, achieving synergistic effect that reduces resistance more effectively than either material alone.
Solution Approach 2:
The patent applies different carbon materials to different functional requirements within the same electrode. The first carbon material is used where structural integrity and electroconductivity are paramount, while the second carbon material is used where high surface area and contact points are needed, optimizing local properties for different functions.
2Power
If electricity storage devices operate at large currents, then the power output and charging speed increase, but the resistance of positive electrodes causes excessive heat generation and thermal runaway
Solution Approach 1:
The composite carbon material structure provides multiple contact points and improved electroconductivity throughout the electrode, reducing overall resistance. This allows the device to handle large currents with reduced heat generation, enabling high power output without thermal runaway.
Solution Approach 2:
The patent changes the physical and chemical parameters of the carbon materials by controlling the exfoliation degree of graphite (creating partially exfoliated structures with specific D/G ratios) and selecting appropriate second carbon materials. These parameter changes optimize the balance between electroconductivity, surface area, and resistance, enabling high-power operation with controlled 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
The composite electrode material effectively reduces heat generation and improves safety and performance by lowering resistance and enhancing electron conductivity, allowing for higher capacity and better cycle characteristics in electricity storage devices.
Implementation Method 1
a first carbon material having a graphite structure wherein graphite is partially exfoliated
Implementation Method 2
the specific surface area of the flake graphite is small, there are few contact points with the positive electrode active material
Implementation Method 3
the heat generation is caused by the magnitude of the resistance of positive electrodes of the electricity storage devices
Data Source
AI summary
There is provided an electrode material for electricity storage devices, which enables suppression of heat generation in charge and discharge at large currents. The electrode material for electricity storage devices comprises a first carbon material having a graphite structure wherein graphite is partially exfoliated, and a second carbon material different from the first carbon material, wherein the ratio A/B, where A represents a weight of the first carbon material and B represents a weight of the second carbon material, is within the range of 0.01 or higher and 100 or lower.