Electrode Binder Balance for Lithium Plating Suppression
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Solution Overview
Problem
Existing electricity storage devices face challenges in maintaining capacity and high rate characteristics while preventing the precipitation of metal lithium during charging.
Innovation Solution
The proposed electricity storage device features a positive electrode with a composite material layer thickness of 40 μm or more and a binder content rate between 0.1 wt% and 5.0 wt%, and a negative electrode with a composite material layer thickness of 50 μm or more and a binder content rate between 1.0 wt% and 12.0 wt%, which adjusts the resistance values to suppress metal lithium precipitation and maintain high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the composite material layer of the negative electrode is made thicker to increase capacity, then the capacity of the electricity storage device is improved, but metal lithium precipitation occurs during charging
Solution Approach 1:
The patent changes the binder content rate parameter in the negative electrode composite material layer to a specific range (1.0-12.0 wt%) to control the resistance value, which in turn controls the distribution of electric charge carriers and prevents metal lithium precipitation while maintaining high capacity
Solution Approach 2:
The patent uses a composite material layer containing active material, binder, and conductive assistant agent with specific composition ratios to achieve both high capacity and prevention of metal lithium precipitation through controlled resistance characteristics
2Productivity
If the technique from Japanese Patent Application Publication No. 2014-10888 is used to reduce resistance difference between electrodes, then the high rate characteristic is improved, but the capacity maintenance rate after cycling is significantly reduced
Solution Approach 1:
The patent applies different binder content rates to different electrodes (positive: 0.1-5.0 wt%, negative: 1.0-12.0 wt%) to create local resistance characteristics that are optimized for their specific functions, allowing the negative electrode to have higher resistance to prevent lithium precipitation while the positive electrode maintains lower resistance for good capacity maintenance
Solution Approach 2:
The patent changes the resistance value parameter of the negative electrode to a specific range (3-90 Ω/cm2) by controlling binder content, which resolves the contradiction between high rate characteristic and capacity maintenance rate by creating an optimal resistance balance between electrodes
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 enhances both the high rate characteristic and capacity maintenance rate of the electricity storage device while effectively preventing metal lithium precipitation, thereby improving safety and performance.
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
An electricity storage device, such as lithium ion secondary battery, nickel hydrogen battery, the other secondary batteries
Data Source
AI summary
An electricity storage device is provided in which, while a capacity maintenance rate and a high rate characteristic are maintained.In the electricity storage device, a membrane thickness of a positive electrode composite material layer is equal to or more than 40 μm and a membrane thickness of a negative electrode composite material layer is equal to or more than 50 μm. A binder content rate in the positive electrode composite material layer is equal to or more than 0.1 wt % and not more than 5.0 wt % when a solid content weight in the whole positive electrode composite material layer is treated as 100 wt %. A binder content rate in the negative electrode composite material layer is equal to or more than 1.0 wt % and not more than 12.0 wt % when a solid content weight of the whole negative electrode composite material layer is treated as 100 wt %.