Solid-State Battery Electrode Gradient for High-Current Cycle Retention
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Solution Overview
Problem
All-solid-state secondary batteries face challenges in maintaining capacity retention and cycle characteristics during high-current charge and discharge due to uneven reaction distribution and material expansion/shrinkage, leading to decreased performance.
Innovation Solution
The electrical storage element is structured with a higher content rate of solid electrolyte to electrode active material near the solid electrolyte layer, and a gradient increase in this ratio towards the current collector layer, reducing uneven reaction distribution and material expansion/shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sintered all-solid-state secondary battery is formed by firing a solid electrolyte layer and an electrode layer, then the battery structure is simplified and manufacturing is easier, but when charge and discharge are repeated, the charge and discharge performance decreases and cycle characteristics deteriorate
Solution Approach 1:
The electrode layer is designed with a non-uniform solid electrolyte content distribution, where the solid electrolyte content is higher near the solid electrolyte layer interface and lower near the current collector layer. This local quality variation optimizes reaction uniformity at the interface while maintaining overall battery performance, resolving the contradiction between simplified manufacturing and improved cycle characteristics.
2Power
If charge and discharge are performed at high currents, then power output is improved, but capacity retention decreases due to uneven reaction distribution
Solution Approach 1:
By creating a gradient distribution of solid electrolyte content within the electrode layer, the invention optimizes local reaction conditions. The higher solid electrolyte content near the interface promotes uniform reaction distribution during high-current operation, preventing localized overheating and maintaining capacity retention while enabling high power output.
Solution Approach 2:
The invention changes the compositional parameter of the electrode layer by varying the solid electrolyte to electrode active material content ratio throughout the layer thickness. This parameter gradient allows the battery to maintain stable capacity retention during high-current charge and discharge by optimizing ion transport and reaction distribution.
3Stability of the object's composition
If the electrode layer has high solid electrolyte content near the solid electrolyte layer, then reaction uniformity is improved, but the overall capacity may be reduced
Solution Approach 1:
The electrode layer employs a gradient composition where solid electrolyte content is optimized locally rather than uniformly throughout. The higher solid electrolyte content near the interface ensures uniform reaction distribution, while the lower content toward the current collector preserves more electrode active material for capacity, achieving a balance between reaction uniformity and overall capacity.
Solution Approach 2:
Instead of varying solid electrolyte content uniformly in one dimension, the invention introduces a spatial gradient along the thickness direction of the electrode layer. This dimensional variation allows simultaneous optimization of reaction uniformity at the interface and capacity utilization throughout the electrode volume.
Data Source
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AI summary
Provided is an electrical storage element that can increase the capacity retention of a secondary battery during charge and discharge at high currents and the cycle characteristics of the secondary battery during repeated charge and discharge. An electrical storage element 1 includes: a solid electrolyte layer 2; an electrode layer 3 provided on one principal surface of the solid electrolyte layer 2 and containing an electrode active material 5 and a solid electrolyte 6a, 6b; and a current collector layer 4 provided on a principal surface of the electrode layer 3 opposite to the solid electrolyte layer 2 side, wherein a first electrode layer portion 3A of the electrode layer 3 disposed on the solid electrolyte layer 2 side than a middle of the electrode layer 3 in a direction of thickness of the electrode layer 3 has a higher content rate of the solid electrolyte 6a, 6b to the electrode active material 5 than a second electrode layer portion 3B of the electrode layer 3 disposed on the current collector layer 4 side than the middle of the electrode layer 3 in the direction of thickness of the electrode layer 3.