Multilayer Electrode Porosity Gradient for Ionic Conductivity
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Solution Overview
Problem
Conventional lithium-ion batteries face limitations in ionic conductivity and electrolyte distribution due to uniform electrode compression, leading to issues like electrolyte starvation and reduced charge/discharge rates, which affect their performance and energy density.
Innovation Solution
The introduction of a multilayer electrode structure with a first layer adjacent to the current collector and a second layer containing non-active mesoporous or macroporous ceramic particles, which have a higher resistance to densification, creating a favorable porosity profile that enhances ionic conductivity by allowing greater compression of the first layer and maintaining porosity near the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional multilayer electrodes are used during calendering, then the electrode is densified to improve mechanical strength and reduce porosity, but this leads to uneven densification and electrolyte starvation in certain regions
Solution Approach 1:
The patent applies local quality by creating distinct layers with different properties: the first layer (adjacent to current collector) has higher porosity and lower density to maintain electrolyte access, while the second layer (intermediate layer) has lower porosity and higher density for mechanical strength. This spatial variation in porosity and density throughout the electrode thickness resolves the contradiction between mechanical strength and ionic conductivity by optimizing each layer's properties for its specific function.
Solution Approach 2:
The electrode is segmented into multiple layers with different characteristics. The first layer contains active material particles with higher porosity to ensure electrolyte penetration and ionic conductivity near the current collector. The second layer contains active material particles with lower porosity to provide mechanical strength and structural integrity. This segmentation allows each layer to independently optimize for its primary function, resolving the contradiction between strength and ionic conductivity.
2Reliability
If the electrode porosity is increased to improve ionic conductivity, then ion transport is enhanced, but the mechanical strength and structural integrity of the electrode decreases
Solution Approach 1:
Different regions of the electrode have different porosity levels optimized for their specific functions. The first layer near the current collector has higher porosity (0.3-0.6) to maximize ionic conductivity and electrolyte access. The second layer has lower porosity (0.1-0.3) to provide mechanical strength and structural support. This local variation in porosity resolves the contradiction by ensuring high ionic conductivity where needed while maintaining structural integrity where required.
Solution Approach 2:
The electrode structure is divided into segments with different porosity characteristics. The first layer segment is designed with higher porosity to facilitate ion transport, while the second layer segment is designed with lower porosity to provide mechanical reinforcement. This segmentation strategy allows the electrode to simultaneously achieve high ionic conductivity and adequate mechanical strength through functional specialization of different regions.
3Device complexity
If uniform active material is distributed throughout the electrode, then the electrode structure is simple, but this leads to capacity utilization limitations due to electrolyte starvation
Solution Approach 1:
The patent implements local quality by varying the active material distribution and porosity characteristics across different layers. The first layer has higher porosity and is positioned to receive preferential electrolyte access, while the second layer has lower porosity and contains active material optimized for mechanical support. This non-uniform distribution resolves the contradiction by ensuring that active material is strategically placed in regions with adequate electrolyte supply, thereby maximizing capacity utilization without excessive structural complexity.
Solution Approach 2:
The electrode structure is designed in advance with a specific layered architecture that pre-establishes favorable porosity gradients and active material distribution patterns. The first layer is configured with higher porosity before assembly to ensure optimal electrolyte penetration and ion transport pathways are established from the beginning. This preliminary structural design prevents electrolyte starvation and maximizes capacity utilization without requiring complex operational adjustments.
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 improves ionic conductivity and mitigates electrolyte starvation, enhancing the lithiation/delithiation rate capability and overall performance of lithium-ion batteries by optimizing the porosity profile across the electrode thickness.
Implementation Method 1
the non-active ceramic particles are configured to conduct ions between the first layer and the separator through the non-active mesoporous or macroporous ceramic material of the non-active ceramic particles
Implementation Method 2
the non-active ceramic particles each consist of a non-active mesoporous or macroporous ceramic material configured to provide conduction channels through pores of the non-active ceramic particles into the first layer
Data Source
AI summary
Electrochemical cells of the present disclosure may include one or more multilayered electrodes. One or both multilayered electrodes may be configured such that a second layer farther from the current collector has a higher resistance to densification than a first layer closer to the current collector. This may be achieved by including a plurality of non-active ceramic particles in the second layer. Accordingly, calendering of the electrode results in a greater compression of the first layer, and a beneficial porosity profile is created. This may improve the ionic conductivity of the electrode, as compared with known systems.