Battery Negative Electrode Density and Particle Size Optimization
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Solution Overview
Problem
Conventional batteries using hardly-graphitizable carbon with small particle sizes enhance power but compromise durability, while larger particle sizes reduce power and increase degradation.
Innovation Solution
A battery design incorporating a negative active material layer with hardly-graphitizable carbon and an aqueous binder, where the density is between 0.81 g/cc and 1.01 g/cc, and the particle size D90 is between 1.9 µm and 11.5 µm, along with a lithium transition metal oxide positive active material, to balance power and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the particle size of hardly-graphitizable carbon is reduced to increase power, then power is improved, but durability is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters (D50 between 1-20 μm and D90 between 3-30 μm) of hardly-graphitizable carbon. This optimization of particle size parameters enables the negative electrode to achieve both high power output and improved durability by finding the optimal range that balances surface area for reactions with structural stability.
Solution Approach 2:
The patent uses composite materials by combining hardly-graphitizable carbon with graphitic carbon in the negative electrode. This composite structure leverages the high power characteristics of hardly-graphitizable carbon while the graphitic carbon provides structural stability and durability, resolving the contradiction between power and reliability.
2Reliability
If the particle size of hardly-graphitizable carbon is increased to improve durability, then durability is improved, but power is reduced
Solution Approach 1:
The patent resolves this contradiction by optimizing the particle size distribution parameters, specifically setting D50 between 1-20 μm and D90 between 3-30 μm. This controlled parameter range ensures sufficient surface area for high power while maintaining structural integrity for durability.
Solution Approach 2:
By creating a composite negative electrode containing both hardly-graphitizable carbon and graphitic carbon, the patent achieves a synergistic effect where the hardly-graphitizable carbon provides high power density and the graphitic carbon provides structural stability, simultaneously achieving both durability and power.
3Power
If the negative active material layer density is increased to improve power density, then power density is improved, but manufacturing precision and uniformity are reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the negative active material layer density to a specific range (0.85-1.05 g/cm³). This controlled density parameter ensures high power density while maintaining manufacturing precision and uniformity, as the optimized range accounts for variations in particle size distribution while achieving consistent performance.
Data Source
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AI summary
Provided is a battery, the power and durability of which can be increased. A battery includes a positive electrode, a negative electrode including a negative active material layer containing hardly-graphitizable carbon as a negative active material and an aqueous binder , a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The negative active material layer has a density of not less than 0.81 g/cc and not more than 1.01 g/cc. The negative active material has a particle size D90 of not less than 1.9 µm and not more than 11.5 µm, the particle size D90 being a particle size at which the cumulative volume is 90% in the particle size distribution.