Spheroidized Graphite Negative Electrode Material for Battery
Solution Overview
Problem
Nonaqueous electrolyte secondary batteries using scaly graphite particles face issues with discharge load characteristics, cycle characteristics, and irreversible capacity due to poor adhesiveness and thermal stability, leading to safety concerns and reduced performance.
Innovation Solution
Graphite particles with a block-like structure and a carbon layer on their surface, having a specific aspect ratio, pore volume, and carbon content, are used to create a negative electrode material with improved discharge capacity, charge/discharge efficiency, and charge load characteristics, along with a manufacturing method involving thermoplastic polymer compounds and controlled carbonization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If scaly graphite particles with large aspect ratio are used, then graphite crystal structure is formed, but adhesiveness with current collector deteriorates and binder amount increases
Solution Approach 1:
The patent applies spherical化处理 to convert scaly graphite particles with large aspect ratio into particles with spherical or near-spherical morphology. This curvature transformation reduces the alignment tendency during electrode manufacturing and improves adhesiveness with the current collector, directly resolving the contradiction between maintaining graphite crystal structure and achieving reliable adhesion.
Solution Approach 2:
The patent changes the morphological parameters of graphite particles by controlling the spheroidization process to achieve specific aspect ratio ranges and surface characteristics. This parameter optimization allows the particles to maintain graphite crystallinity while achieving improved adhesiveness and reduced binder requirements.
2Stability of the object's composition
If scaly graphite particles are used, then graphite structure is achieved, but discharge load characteristics and cycle characteristics deteriorate
Solution Approach 1:
By transforming the scaly morphology into spherical particles, the patent eliminates the distortion generated in the c-axis direction during lithium storage and release cycles. This prevents internal electrode destruction and maintains both discharge load characteristics and cycle characteristics while preserving the graphite structure.
Solution Approach 2:
The patent optimizes particle morphology parameters through spheroidization to achieve aspect ratios within specific ranges, which prevents the alignment-induced distortion that deteriorates discharge performance and cycle life, thereby resolving the contradiction between graphite structure stability and discharge characteristics.
3Stability of the object's composition
If scaly graphite particles with large specific surface area are used, then graphite crystallinity is achieved, but irreversible capacity at first cycle increases
Solution Approach 1:
The spherical morphology reduces the specific surface area compared to scaly particles with the same volume, thereby reducing the total surface area available for irreversible reactions during the first cycle. This resolves the contradiction between maintaining graphite crystallinity and minimizing irreversible capacity loss.
Solution Approach 2:
By changing the morphological parameters to achieve spherical particles with controlled surface area, the patent reduces the irreversible capacity at first cycle while maintaining the necessary graphite crystallinity for proper lithium intercalation and deintercalation.
4Stability of the object's composition
If scaly graphite particles are used, then graphite structure is formed, but thermal stability when lithium is stored decreases
Solution Approach 1:
The spherical particle morphology improves thermal stability by reducing the aspect ratio and eliminating the aligned layered structure that is prone to thermal runaway. The curved surface geometry of spherical particles provides better thermal management and stability when lithium is stored, resolving the contradiction between graphite structure and thermal stability.
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 solution results in a nonaqueous electrolyte secondary battery with enhanced rapid charge/discharge characteristics, reduced irreversible capacity, and improved safety, suitable for portable electronics and electric vehicles.
Implementation Method 1
a carbon layer formed on a surface of the graphite particle
Data Source
AI summary
In order to provide a nonaqueous electrolyte secondary battery negative electrode material that has an excellent discharging capacity, the charge/discharge efficiency and the charge load characteristics, a manufacturing method thereof, a nonaqueous electrolyte secondary battery negative electrode with the negative electrode material and a nonaqueous electrolyte secondary battery, the invention provides a nonaqueous electrolyte secondary battery negative electrode material including graphite particles that have a block-like structure where a plurality of flat graphite fine particles assembles or bonds non-parallel with each other, the aspect ratio of 5 or less and a volume of fine pores in the range of 10 to 105 nm in a volume of 400 to 2000 cm3/kg; and a layer of carbon formed on a surface of the graphite particle, wherein a ratio (by weight ratio) of the layer of carbon to the graphite particle is in the range of 0.001 to 0.01, a manufacturing method thereof, a nonaqueous electrolyte secondary battery negative electrode with the negative electrode material and a nonaqueous electrolyte secondary battery.