Negative Electrode Particle Size Control for Energy Storage
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Solution Overview
Problem
Conventional energy storage devices face challenges in improving input performance while maintaining cycle performance, as reducing the particle size of graphite and non-graphitizable carbon can lead to deteriorated cycle performance.
Innovation Solution
An energy storage device with a negative electrode comprising graphite particles and non-graphitizable carbon, where the D50 particle size of graphite is 2 µm or more and the mass ratio of non-graphitizable carbon to the total mass is 15% to 20%, and the D50 particle size of non-graphitizable carbon is 2 µm to 4.5 µm, with a ratio of D50 particle sizes of graphite to non-graphitizable carbon being 1.02 or less, to enhance input performance and retain capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the particle size of graphite and non-graphitizable carbon is reduced to improve input performance, then input performance is improved, but cycle performance is deteriorated
Solution Approach 1:
The patent applies parameter changes by precisely controlling the D50 particle size of graphite to 2 µm or more and the mass ratio of non-graphitizable carbon to 15-20%, while maintaining the D50 particle size ratio between graphite and non-graphitizable carbon at 1.02 or less. These specific parameter ranges optimize both input performance and cycle performance by preventing excessive particle size reduction that would harm cycle stability.
Solution Approach 2:
The patent uses composite materials by combining graphite particles with non-graphitizable carbon in a specific mass ratio of 15-20%. This composite structure leverages the high capacity of graphite while the non-graphitizable carbon component maintains structural integrity during cycling, thus improving input performance without sacrificing cycle performance.
2Reliability
If the particle size of graphite is increased to maintain cycle performance, then cycle performance is maintained, but input performance is reduced
Solution Approach 1:
The patent optimizes the D50 particle size of graphite to be 2 µm or more, which is a specific parameter setting that balances cycle performance maintenance with adequate input performance. This parameter is carefully controlled to avoid both excessive reduction (which harms cycle performance) and excessive increase (which would reduce input performance).
Solution Approach 2:
The patent applies local quality by creating a specific size distribution where graphite particles with D50 of 2 µm or more are used, and the ratio of D50 particle sizes between graphite and non-graphitizable carbon is controlled at 1.02 or less. This localized optimization of particle size characteristics ensures both cycle stability and acceptable input performance.
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 improves input performance and suppresses capacity reduction after cycles, maintaining excellent cycle performance by preventing conductive path disruptions during repeated charge-discharge.
Implementation Method 1
a negative electrode capable of absorbing/desorbing lithium ions
Data Source
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AI summary
An energy storage device includes a positive electrode and a negative electrode. The negative electrode includes graphite and non-graphitizable carbon and a D50 particle size of the graphite at which a cumulative volume in a particle size distribution of a particle size reaches 50% is 2 µm or more. A ratio of a mass of the non-graphitizable carbon to a total amount of a mass of the graphite and a mass of the non-graphitizable carbon is 5% by mass or more and 45% by mass or less and a ratio of the D50 particle size of the graphite to a D50 particle size of the non-graphitizable carbon is 1.02 or less.