Solid-State Battery Anode Layering for High-Rate Charge Crack Control
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Solution Overview
Problem
All-solid-state batteries with silicon negative electrodes experience charging unevenness, leading to cracks and reduced capacity during high-rate charging due to differences in expansion quantities along the thickness direction, which is more pronounced than in liquid batteries.
Innovation Solution
The battery design includes a negative electrode layer with a first layer and a second layer, where the second layer has a smaller average particle diameter than the first layer, allowing for more even expansion and reducing the likelihood of cracks during high-rate charging by optimizing the particle diameter ratio and ensuring the second layer can accept full charge capacity from the positive electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon material is used as negative electrode active material to increase capacity, then the battery capacity is large, but the expansion quantity during charging is large causing cracks during high-rate charging
Solution Approach 1:
The negative electrode layer is divided into two layers: a first layer containing a first particle group of silicon material with a first average particle diameter, and a second layer containing a second particle group of silicon material with a second average particle diameter smaller than the first. This segmentation allows different regions to experience different expansion characteristics, reducing overall crack formation during high-rate charging while maintaining high capacity.
2Productivity
If high-rate charging is performed to increase charging speed, then productivity is improved, but charging unevenness occurs leading to cracks and reduced battery capacity
Solution Approach 1:
The patent applies local quality by creating a negative electrode layer with spatially varying particle size distribution. The second layer (closer to the positive electrode) contains finer silicon particles with smaller average diameter, while the first layer contains coarser particles. This local differentiation optimizes charging uniformity across the electrode thickness, enabling high-rate charging without excessive charging unevenness and crack formation.
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 enhances high-rate charging resistance by minimizing the frequency of cracks and maintaining battery capacity over repeated charging cycles, as evidenced by improved capacity maintenance ratios in experimental results.
Implementation Method 1
The second particle group expands in preference to the first particle group during high-rate charging. The second particle group has a smaller average particle diameter than the first particle group. It is thought that the second particle group has a smaller expansion quantity than the first particle group.
Data Source
AI summary
An all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. The solid electrolyte layer separates the positive electrode layer and the negative electrode layer. The negative electrode layer includes a first layer and a second layer. The second layer is interposed between the solid electrolyte layer and the first layer. The first layer contains a first particle group. The second layer contains a second particle group. The first particle group and the second particle group contain a silicon material. The second particle group has a smaller average particle diameter than the first particle group.