Gradient-Porosity Battery Electrode for Ion Diffusion Under High Compaction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion power battery electrodes face challenges in achieving high volumetric energy density and kinetic performance due to reduced porosity and blocked pores under high compaction, which impede lithium ion diffusion and degrade electrode performance.
Innovation Solution
The electrode is designed with multiple layers, where the layer closest to the membrane has only large particles, and subsequent layers include both large and small particles, with porosity gradually increasing towards the current collector, allowing for a gradient pore structure that enhances lithium ion diffusion and compaction density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If high compaction pressure is applied to increase volumetric energy density, then compaction density of the electrode is improved, but porosity becomes extremely low and pores are blocked, degrading kinetic performance
Solution Approach 1:
The electrode is divided into multiple layers (first layer, second layer, third layer, etc.) with progressively different compaction densities and porosity levels. The first layer near the membrane has lower compaction density to maintain porosity for ion diffusion, while subsequent layers have progressively higher compaction density to increase volumetric energy density. This segmentation allows simultaneous optimization of both kinetic performance and energy density.
Solution Approach 2:
Different regions of the electrode are assigned different local properties: the first layer near the membrane has lower compaction density and higher porosity to facilitate lithium ion diffusion, while the second, third, and subsequent layers have progressively higher compaction density. This local quality variation ensures that each region performs its specific function optimally - ion transport near the membrane and energy storage in the bulk.
2Reliability
If porosity is increased to improve lithium ion diffusion, then kinetic performance is improved, but compaction density decreases, reducing volumetric energy density
Solution Approach 1:
The electrode is segmented into multiple layers with gradient porosity distribution. The first layer has higher porosity to enable efficient lithium ion diffusion, while subsequent layers have progressively lower porosity and higher compaction density. This segmentation allows the electrode to simultaneously achieve good kinetic performance in the ion transport region and high volumetric energy density in the bulk storage region.
Solution Approach 2:
The electrode structure implements local quality variation where the first layer near the membrane has higher porosity for optimal ion diffusion, while the second, third, and subsequent layers have progressively lower porosity and higher compaction density. This local optimization allows each layer to perform its specific function - ion transport or energy storage - at maximum efficiency.
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 design improves the electrode's kinetic performance and volumetric energy density by maintaining high compaction while facilitating efficient lithium ion diffusion, resulting in higher discharge retention and lower impedance.
Implementation Method 1
The mixture is heated, to bring the bonding agent into a molten state
Implementation Method 2
The bonding agent in the molten state is cured, the cured bonding agent wrapping the electrode material
Implementation Method 3
lithium ions moving between positive and negative electrodes
Data Source
AI summary
An electrode includes n electrode plate layers sequentially stacked. The electrode plate layer close to a membrane side of the battery is the 1st layer, and the electrode plate layer close to a current collector side is the nth layer. N is a natural number greater than or equal to 2. An electrode material of the electrode plate layer at the 1st layer includes first particles, and an electrode material of the electrode plate layer at each layer from the 2nd layer to the nth layer includes at least the first particles and second particles. An average particle size of the first particles is greater than an average particle size of the second particles. Porosity of the electrode plate layers gradually increases layer by layer in a direction from the nth layer to the 1st layer.