Layered Negative Electrode Binder Profile to Suppress Metal Precipitation
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Solution Overview
Problem
In electricity storage devices, the precipitation of metal charge carriers on the negative electrode composite material layer during charging reduces the capacity maintenance rate and poses safety concerns.
Innovation Solution
The electricity storage device incorporates a negative electrode composite material layer with a laminate structure of n layers, where the binder content rate in the surface layer is between 5.0 wt% and 35.0 wt%, and the binder content rate in the layer closer to the current collector foil satisfies a specific ratio, thereby controlling the resistance value and preventing metal precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the resistance of the negative electrode is reduced to improve charge/discharge performance, then the output and input performance is enhanced, but the precipitation of metal charge carriers on the negative electrode surface is accelerated
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the binder content varies across different layers. The surface layer has a specific binder content rate (5-35 wt%) that differs from inner layers, with the binder content rate satisfying a specific ratio relationship between layers. This gradient structure locally optimizes each layer's properties to balance conductivity and precipitation suppression.
Solution Approach 2:
The patent changes the binder content rate parameter across different layers to resolve the contradiction. By controlling the binder content rate in the surface layer to be within 5-35 wt% and maintaining a specific ratio relationship between layers, the electrode achieves both adequate conductivity for power performance and sufficient resistance to prevent metal precipitation.
2Object-affected harmful factors
If the binder content rate in the surface layer is increased to suppress metal precipitation, then the safety is improved, but the electrical resistance increases
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the binder content content varies across different layers. The surface layer has a specific binder content rate (5-35 wt%) that differs from inner layers, with the binder content rate satisfying a specific ratio relationship between layers. This gradient structure locally optimizes each layer's properties to balance conductivity and precipitation suppression.
Solution Approach 2:
The patent changes the binder content rate parameter across different layers to resolve the contradiction. By controlling the binder content rate in the surface layer to be within 5-35 wt% and maintaining a specific ratio relationship between layers, the electrode achieves both adequate conductivity for power performance and sufficient resistance to prevent metal precipitation.
3Ease of manufacture
If a uniform binder distribution is used to simplify manufacturing, then the manufacturing process is easier, but the capacity maintenance rate decreases due to metal precipitation
Solution Approach 1:
The patent applies segmentation by dividing the negative electrode composite material layer into multiple layers with different binder content rates. Instead of a uniform distribution, the layer is segmented into a surface layer and inner layers, each with optimized binder content to perform specific functions: the surface layer suppresses metal precipitation while inner layers maintain conductivity.
Solution Approach 2:
The patent applies local quality by creating a multi-layer structure where the binder content varies across different layers. The surface layer has a specific binder content rate (5-35 wt%) that differs from inner layers, with the binder content rate satisfying a specific ratio relationship between layers. This gradient structure locally optimizes each layer's properties to balance conductivity and precipitation suppression.
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 suppresses the precipitation of metal charge carriers, maintains a high capacity maintenance rate, and enhances safety by optimizing the binder distribution and resistance values within the negative electrode composite material layer.
Implementation Method 1
The binder is contributed in binding the active material and the current collector foil, in binding the active materials to each other
Implementation Method 2
a technique is known that can enhance a capacity maintenance rate of the electricity storage device by reducing an electrical resistance of the electrode
Implementation Method 3
an average resistance value from the first layer positioned closer to the current collector foil to the nth layer positioned closer to the separator is equal to or more than 15 Ω/cm2 and not more than 50 Ω/cm2
Data Source
AI summary
A negative electrode composite material layer is configured with a laminate structure that consists of n layers (the n is a natural number being equal to or more than 2) from a first layer positioned closer to a negative electrode current collector foil to a nth layer positioned closer to a separator, here a binder content rate (A) of the nth layer is equal to or more than 5.0 wt % and not more than 35.0 wt % when a solid content weight of a whole of the nth layer is treated as 100 wt %, a binder content rate (B) of the first layer satisfies 1.10≤A/B≤62.50 when a solid content weight of a whole of the first layer is treated as 100 wt %. An average resistance value of the negative electrode composite material layer is equal to or more than 15 Ω/cm2 and not more than 50 Ω/cm2.