Non-graphitizable Carbon Negative Electrode Density and Particle Size Control
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Solution Overview
Problem
Conventional energy storage devices using non-graphitizable carbon as a negative electrode active material face a trade-off between increased output and durability, where smaller particle sizes enhance output but reduce durability, and larger particle sizes improve durability but may lead to reduced capacity and output due to inadequate contact between electrodes.
Innovation Solution
The energy storage device incorporates a negative electrode active material layer with non-graphitizable carbon, where the density is controlled between 0.92 g/cc and 1.13 g/cc, and the particle size D90 is between 4.3 µm and 8.5 µm, ensuring optimal contact and reducing wrinkles, thereby achieving high durability and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If non-graphitizable carbon with smaller particle size is used to increase output, then output is improved, but durability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters (D10, D50, D90) of non-graphitizable carbon and the density of the negative electrode active material layer. By optimizing these parameters within specific ranges, the invention achieves both high output and high durability, resolving the trade-off between power and reliability.
2Reliability
If non-graphitizable carbon with larger particle size is used to improve durability, then durability is improved, but capacity and output deteriorate due to inadequate contact between electrodes
Solution Approach 1:
The patent resolves this contradiction by changing the particle size distribution parameters to a specific range (D10: 1.8-3.5 μm, D50: 2.7-4.6 μm, D90: 4.3-8.5 μm) and controlling the density (0.92-1.13 g/cc), which ensures adequate contact between electrodes while maintaining durability.
3Power
If density of negative electrode active material layer is increased to improve contact, then output is improved, but wrinkles occur causing production difficulties
Solution Approach 1:
The patent applies parameter changes by controlling the density of the negative electrode active material layer within the range of 0.92-1.13 g/cc. This optimized density range ensures good contact between electrodes for high output while preventing wrinkles that would cause production difficulties.
Data Source
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AI summary
An energy storage device (10) including a positive electrode (410), a negative electrode (420), a separator (431 or 432) disposed between the positive electrode (410) and the negative electrode (420), and a non-aqueous electrolyte, wherein the negative electrode (420) includes a negative electrode active material layer (422) containing a non-graphitizable carbon as a negative electrode active material, and the negative electrode active material has a negative electrode active material weight per unit volume of the negative electrode active material layer (422) of 0.92 g/cc or more and 1.13 g/cc or less and a particle size D90 of 4.3 µm or more and 11.5 µm or less, the particle size D90 being a particle size in particle size distribution in which a cumulative volume is 90%.