Layered Battery Electrode Binder Coverage for High-Temperature Storage
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Solution Overview
Problem
Battery capacity durability degrades and resistance increases during high-temperature storage due to binder swelling, which can be exacerbated by excessive binder amounts in the electrode layer.
Innovation Solution
An electrode structure with a first electrode layer having a high binder coverage and a second electrode layer with a lower binder coverage, where the first binder coverage is greater than 50% and the second binder coverage is 50% or less, using fluorine-containing binders, and both layers include active materials and conductive materials dispersed with their respective binders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the binder amount in the electrode layer is increased to suppress binder swelling during high temperature storage, then capacity durability is improved, but the resistance increase rate becomes large
Solution Approach 1:
The patent applies local quality by creating a multi-layered electrode structure where different layers have different binder contents. The first electrode layer (near current collector) has higher binder content to maintain adhesion and suppress swelling at the critical interface, while the second electrode layer (outer layer) has lower binder content to minimize overall resistance increase. This spatial differentiation of binder distribution resolves the contradiction between maintaining capacity durability and suppressing resistance increase.
Solution Approach 2:
The electrode layer is segmented into multiple layers with distinct binder concentrations. By dividing the single electrode layer into first and second layers with different binder contents, the patent enables each layer to fulfill different functions: the first layer prioritizes adhesion and swelling suppression, while the second layer prioritizes low resistance. This segmentation allows simultaneous optimization of both capacity durability and resistance characteristics.
2Reliability
If the binder amount is increased to maintain bonding force during high temperature storage, then capacity durability is improved, but electron conductivity at the interface degrades
Solution Approach 1:
The patent implements local quality by concentrating higher binder content in the first electrode layer that directly contacts the current collector, where bonding force is most critical. The outer second layer uses lower binder content to maintain electron conductivity. This localized optimization ensures adequate adhesion at the interface without compromising overall electron transport pathways.
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 inhibits the increase in resistance while maintaining capacity durability by preventing binder-induced swelling and maintaining electron conductivity.
Implementation Method 1
a first binder covering a surface of the first active material; a second binder covering a surface of the second active material
Implementation Method 2
a binder in the electrode layer is swelled by the liquid electrolyte during high temperature storage
Data Source
AI summary
An electrode to be used for a battery, the electrode including: a current collector, a first electrode layer arranged on the current collector, and a second electrode layer arranged on the first electrode layer, wherein the first electrode layer includes a first active material, and a first binder covering a surface of the first active material; the second electrode layer includes a second active material, and a second binder covering a surface of the second active material; and when C1 (%) designates a coverage of the first binder with respect to the first active material, and C2 (%) designates a coverage of the second binder with respect to the second active material, the C1 is larger than the C2.