Mixed Graphite Particle Morphology for Battery Tap Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries with graphite-based negative electrodes require improved cycle characteristics to enhance performance and longevity.
Innovation Solution
A graphite-based negative electrode active material comprising a spheroidized first graphite particle and a second graphite particle with lower roundness, where the second particle is added in a specific mass range, optimizing particle size distribution and tap density to enhance electroconductivity and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only spheroidized graphite particles are used to improve roundness and electroconductivity, then electroconductivity is improved, but tap density decreases
Solution Approach 1:
The patent combines spheroidized graphite particles (high roundness, good electroconductivity) with scale-shaped graphite particles (lower roundness, high tap density) in a mixed composition. This merging of different particle morphologies allows the negative electrode to simultaneously achieve satisfactory electroconductivity through the spheroidized particles and high tap density through the scale-shaped particles, resolving the contradiction between these two properties.
Solution Approach 2:
The patent applies different particle characteristics to different functional requirements: spheroidized particles are utilized for their electroconductivity benefits in specific regions, while scale-shaped particles are utilized for their density benefits in other regions. This local quality approach allows each particle type to optimize its contribution to the overall electrode performance without compromising the other property.
2Volume of stationary object
If scale-shaped graphite particles are used to increase tap density, then tap density is improved, but cycle characteristics worsen
Solution Approach 1:
The patent merges scale-shaped graphite particles (providing high tap density) with spheroidized graphite particles (providing excellent cycle characteristics). The spheroidized particles, with their rounded morphology and better stress distribution, contribute to improved cycle stability and reduced capacity fading. This combination allows the electrode to achieve both high tap density from the scale-shaped particles and good cycle characteristics from the spheroidized particles.
Solution Approach 2:
The negative electrode active material is designed as a composite mixture of two different graphite particle types with complementary properties. The scale-shaped particles provide structural density, while the spheroidized particles provide cycle stability. This composite material approach allows the electrode to exhibit both high tap density and excellent cycle characteristics, overcoming the limitations of using a single particle morphology.
3Reliability
If graphite particles with high roundness are used to reduce resistance, then electroconductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines readily available scale-shaped graphite particles (easy to manufacture, high density) with spheroidized graphite particles (improved electroconductivity). The scale-shaped particles can be obtained through conventional mining and processing methods, while the spheroidized particles can be produced through established spheroidization techniques. By mixing these two commercially available particle types in appropriate ratios, the patent achieves improved electroconductivity without requiring complex manufacturing processes or specialized equipment.
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
The combination of spheroidized and low-roundness graphite particles improves the cycle characteristics of lithium ion secondary batteries by increasing tap density, reducing resistance, and maintaining capacity retention, while controlling costs and impurity effects.
Implementation Method 1
a negative electrode including a negative electrode active material of a carbon material capable of intercalating and deintercalating a lithium ion
Implementation Method 2
the tap density in saturation of the particle mixture of the first graphite particle and the second graphite particle is higher than both the tap density in saturation of the first graphite particle and the tap density in saturation of the second graphite particle
Data Source
AI summary
A graphite-based negative electrode active material including a first graphite particle being spheroidized and a second graphite particle having a roundness lower than the roundness of the first graphite particle, wherein the content of the second graphite particle based on the sum of the first graphite particle and the second graphite particle is in the range of 1 to 30% by mass, the ratio of a median particle diameter (D50) to a particle diameter at 5 cumulative % (D5), D50/D5, in a cumulative distribution of the first graphite particle is smaller than the ratio of a median particle diameter (D50) to a particle diameter at 5 cumulative % (D5), D50/D5, in a cumulative distribution of the second graphite particle, and the tap density in saturation of the particle mixture of the first graphite particle and the second graphite particle is higher than both the tap density in saturation of the first graphite particle and the tap density in saturation of the second graphite particle.