Laminated Negative Electrode Binder Gradient Against Metal Precipitation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electricity storage devices, the precipitation of metal charge carriers on the surface of negative electrode composite material layers during charging reduces the capacity maintenance rate and poses safety risks.
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 value of the negative electrode is reduced to improve charge/discharge performance, then the conductivity of charge carriers is increased, but the precipitation of metal charge carriers on the electrode surface is accelerated
Solution Approach 1:
The patent applies local quality by creating a laminate structure with different binder content rates in different layers. The surface layer has a binder content rate of 5.0-35.0 wt% to increase local resistance and suppress metal precipitation, while the inner layer has a lower binder content rate to maintain overall conductivity for good charge/discharge performance. This spatial differentiation of material properties resolves the contradiction between power and harmful effects.
Solution Approach 2:
The negative electrode composite material layer is segmented into multiple layers with different compositions. By dividing the single-layer structure into a laminate of surface layer and inner layer, each with optimized binder content, the patent simultaneously achieves high power performance (through the conductive inner layer) and suppressed metal precipitation (through the resistive surface layer).
2Reliability
If the binder content rate in the surface layer is increased to suppress metal precipitation, then the resistance value increases and charge carrier conductivity decreases, but the capacity maintenance rate is maintained
Solution Approach 1:
The patent uses local quality by assigning different binder content rates to different layers: the surface layer has high binder content (5.0-35.0 wt%) to provide high resistance and maintain capacity, while the inner layer has low binder content to provide low resistance and maintain conductivity. This localized functional differentiation resolves the contradiction between reliability and power.
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 uniformly distributing charge carriers across 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
by making the binder content rate (A) of the surface layer of the negative electrode composite material layer be higher (in particular, 5.0 wt% to 35.0 wt%), the precipitation of the metal becoming the charge carrier could be suppressed. In short, according to the electricity storage device described above, the resistance value of the surface layer of the negative electrode composite material layer is suitably increased
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A negative electrode composite material layer (42) 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 (42a) positioned closer to a negative electrode current collector foil (41) to a nth layer (42n) positioned closer to a separator (50), here a binder content rate (A) of the nth layer (42n) 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 (42n) is treated as 100 wt%, a binder content rate (B) of the first layer (42a) satisfies 1.10 < A/B < 62.50 when a solid content weight of a whole of the first layer (42a) is treated as 100 wt%. An average resistance value of the negative electrode composite material layer (42) is equal to or more than 15 Ω/cm2 and not more than 50 Ω/cm2.