Solid-State Electrode Binder Gradients for Low-Resistance Interfaces
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Solution Overview
Problem
Current solid-state battery production methods face challenges in achieving high surface-to-surface contact between layers while minimizing ionic and electronic resistance, as increasing binder concentration to enhance contact also increases resistance.
Innovation Solution
Implementing a binder concentration gradient across the interface of electrode and separator layers, where the binder concentration is higher at the surface interface and lower at the layer's edge, achieved through a wet-coating process that allows binder movement during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the binder concentration is increased to enhance surface-to-surface contact between layers, then the contact quality is improved, but the ionic and electronic resistance of the cell increases
Solution Approach 1:
The patent applies local quality by creating a binder concentration gradient where the binder concentration varies spatially within each layer. Specifically, the binder concentration is highest at the interface between the electrode layer and separator layer, and decreases toward the current collector. This localized concentration distribution ensures optimal surface-to-surface contact at the critical interface while minimizing binder content in the bulk, thereby reducing ionic and electronic resistance throughout the cell.
Solution Approach 2:
The patent implements parameter changes by transitioning from a uniform binder concentration to a gradient binder concentration distribution. The binder concentration parameter is varied continuously across the layer thickness, with the concentration at the interface being ±5% or less by weight of the concentration in the bulk. This parameter transformation resolves the contradiction by optimizing contact quality at the interface without proportionally increasing overall binder content and resistance.
2Reliability
If the binder concentration is increased to ensure optimal electrochemical performance, then the electrochemical performance is improved, but the overall resistance of the cell increases
Solution Approach 1:
The patent applies local quality by concentrating binder at the critical interface region where electrochemical contact is needed, rather than uniformly distributing it throughout the layer. The binder concentration gradient ensures that the interface region has sufficient binder for optimal electrochemical performance while the bulk regions have minimal binder, reducing overall resistance.
Solution Approach 2:
The patent transforms the uniform binder concentration parameter into a spatially varying gradient parameter. The binder concentration at the interface is maintained at ±5% or less by weight of the bulk concentration, achieving optimal electrochemical performance at the interface without proportionally increasing overall resistance.
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 approach enhances surface-to-surface contact without increasing overall binder concentration, thereby reducing electronic and ionic resistance in solid-state batteries.
Implementation Method 1
movement of the binder from the electrode layer into the separator layer as the layers are dried
Implementation Method 2
The slurry is then dried to remove the solvent
Data Source
AI summary
Described herein are compositions for solid-state electrochemical cells that include a first layer and a second layer which meet at an interface. Each layer includes a binder, wherein the binder concentration forms a continuous gradient across the interface. Electrochemical cells including the compositions are also described herein.