Solid-State Battery Negative Electrode for Low-Resistance Ion Paths
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Solution Overview
Problem
All-solid-state lithium-ion secondary batteries face challenges in achieving high capacity and charge rate performance due to increased ion transport resistance, which is exacerbated by the tortuosity of the ion conduction path and the decrease in solid electrolyte content in the negative electrode active material layer.
Innovation Solution
A solid-state battery negative electrode with a negative electrode active material layer comprising a negative electrode active material and a solid electrolyte, where the negative electrode active material has an average aspect ratio of more than 0.5 and an average elastic modulus of 370 MPa or less, reducing ion transport resistance and avoiding microcracks from volume expansion during pressure molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the solid electrolyte content in the negative electrode active material layer is decreased to increase capacity, then the battery capacity is improved, but the ion transport resistance increases
Solution Approach 1:
The patent changes the physical parameters of the negative electrode active material by controlling its aspect ratio to be 0.65 or more and elastic modulus to be 370 MPa or less. These parameter changes enable the material to deform and densify under pressure, improving ion conduction path connectivity even when solid electrolyte content is reduced, thus resolving the contradiction between capacity and ion transport resistance
Solution Approach 2:
The patent creates a composite structure where the negative electrode active material with specific aspect ratio and elastic modulus properties works synergistically with the solid electrolyte. The composite material design allows the active material to undergo elastic deformation that enhances ion conduction pathways, enabling high capacity while maintaining low ion transport resistance
2Volume of stationary object
If the negative electrode active material layer is subjected to high pressure molding to improve density, then the battery density is improved, but microcracks may form due to volume expansion
Solution Approach 1:
The patent changes the mechanical parameters of the negative electrode active material by controlling its elastic modulus to be 370 MPa or less. This parameter change enables the material to undergo elastic deformation under pressure rather than forming permanent microcracks, allowing high-density packing while preventing structural damage
Solution Approach 2:
The patent applies beforehand cushioning by designing the negative electrode active material with appropriate elastic modulus and aspect ratio that can absorb and distribute molding pressure uniformly. This pre-designed mechanical property configuration prevents stress concentration that would lead to microcrack formation during the high-pressure molding process
3Reliability
If the aspect ratio of the negative electrode active material is increased to improve ion conduction, then the ion transport resistance is reduced, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent changes the geometric parameter of the negative electrode active material by specifying an aspect ratio of 0.65 or more. This parameter change optimizes the balance between ion conduction capability and manufacturing feasibility, as the specific aspect ratio range provides sufficient ion conduction pathways while remaining controllable through conventional spheroidization and processing techniques
Data Source
AI summary
A solid-state battery negative electrode of the present disclosure includes a negative electrode active material layer, the negative electrode active material layer including a negative electrode active material and a solid electrolyte. The negative electrode active material in the negative electrode active material layer has an average aspect ratio of more than 0.5. The negative electrode active material has an average elastic modulus of 370 MPa or less. A solid-state battery of the present disclosure includes: a positive electrode; a negative electrode; and a solid electrolyte layer provided between the positive electrode and the negative electrode. The negative electrode is the solid-state battery negative electrode.