Patterned Battery Electrodes With Low-Tortuosity Ion Channels
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Solution Overview
Problem
Elevated tortuosity in lithium-ion battery electrodes increases ion travel distance, leading to compositional gradients, lithium plating, and design limitations, reducing battery performance and capacity.
Innovation Solution
A method involving the injection of a miscible non-solvent fluid into a wet electrode slurry to induce phase inversion of the binder, creating low-tortuosity channels through non-solvent-induced solidification, facilitating direct lithium-ion transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode thickness is increased to enhance energy density, then the battery capacity is improved, but the ion transport path becomes more tortuous leading to compositional gradients and lithium plating
Solution Approach 1:
The electrode is segmented into multiple functional zones with different binder concentrations. A first binder concentration is applied near the current collector to ensure strong adhesion, while a second, lower binder concentration is applied toward the electrolyte interface to reduce tortuosity and improve ion transport. This segmentation allows the electrode to simultaneously achieve high capacity and maintain reliable ion transport pathways.
Solution Approach 2:
Different regions of the electrode are assigned different binder properties to optimize local functions. The region near the current collector has higher binder content for mechanical stability and adhesion, while the region near the electrolyte interface has lower binder content to minimize tortuosity and facilitate lithium-ion transport. This local quality variation resolves the contradiction between capacity and transport efficiency.
2Strength
If the binder concentration is increased to improve electrode mechanical stability, then the electrode structure is strengthened, but the tortuosity increases reducing ion diffusivity
Solution Approach 1:
The electrode coating process is segmented into multiple stages with varying binder concentrations. The first stage applies a higher binder concentration near the current collector to ensure mechanical stability and strong adhesion. The second stage applies a lower binder concentration toward the electrolyte interface to reduce tortuosity and enhance ion diffusivity. This segmentation allows the electrode to achieve both mechanical strength and ion transport efficiency.
Solution Approach 2:
The electrode is designed with spatially varying binder concentration, creating local quality differences. The region adjacent to the current collector possesses higher binder content for mechanical reinforcement, while the region closer to the electrolyte exhibits lower binder content to minimize tortuosity and maximize ion diffusivity. This local quality optimization resolves the contradiction between strength and ion transport.
3Ease of manufacture
If the electrode thickness is increased to reduce material usage per unit area, then the manufacturing cost is reduced, but the charging speed decreases due to longer ion transport paths
Solution Approach 1:
The electrode structure is segmented with optimized binder distribution to enable thicker electrodes without compromising charging speed. By concentrating binder near the current collector and reducing it toward the electrolyte interface, the electrode maintains mechanical integrity at greater thicknesses while preserving low-tortuosity pathways for rapid ion transport, thus achieving both cost efficiency and high charging speed.
Solution Approach 2:
The electrode employs local quality variation in binder concentration to decouple thickness from charging performance. Thicker regions near the current collector benefit from high binder content for structural support, while thinner effective transport regions near the electrolyte maintain low tortuosity for fast charging. This allows increased areal capacity without sacrificing charging speed.
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
Reduces tortuosity, mitigates lithium plating, and enhances charging speed and energy density by providing direct ion pathways within the electrode.
Implementation Method 1
initiate non-solvent-induced phase inversion of the binder in contact with the miscible non-solvent fluid such that the binder in contact with the miscible non-solvent fluid solidifies around the column into a solid-free channel
Implementation Method 2
injected with a column of miscible non-solvent fluid to displace the electrode slurry mixture
Implementation Method 3
the binder in contact with the miscible non-solvent fluid solidifies around the column into a solid-free channel
Data Source
AI summary
In one aspect of the disclosure, a method is presented. The method involves coating a conductive substrate with an electrode slurry of solvent, active material, binder, and additives to form a wet electrode. The wet electrode is injected with a column of miscible non-solvent fluid into a surface of the wet electrode to displace the electrode slurry around the column and initiate non-solvent-induced phase inversion of the binder in contact with the miscible non-solvent fluid such that the binder in contact with the miscible non-solvent fluid solidifies around the column into a solid-free channel at the surface of and into the wet electrode.