Graphite Negative Electrode Material for Fast Charging and Low Expansion
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Solution Overview
Problem
Existing negative electrode materials for nonaqueous secondary batteries face issues with high-temperature storage characteristics, rapid charge-discharge characteristics, electrode expansion, and pressability, which affect capacity and performance.
Innovation Solution
A negative electrode material comprising graphite with controlled pore volume, thermal properties, and specific Raman values, and a graphite-based material with controlled mercury intrusion and extrusion volumes, ensuring high capacity, limited electrode expansion, and improved pressability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If amorphous carbon is coated on graphite particles to improve capacity and charge-discharge characteristics, then rapid charge-discharge characteristics are improved, but high-temperature storage characteristics deteriorate
Solution Approach 1:
The patent applies different carbon materials with distinct properties to different regions of the electrode system. Specifically, amorphous carbon is used in controlled amounts on graphite particle surfaces to enhance charge-discharge rates, while the bulk graphite structure maintains its crystalline order to preserve thermal stability. This spatial differentiation of material properties resolves the contradiction between rapid charging and high-temperature storage.
Solution Approach 2:
The patent precisely controls the quantity of amorphous carbon coating and the pore volume parameters (0.03-0.15 mL/g) to optimize performance. By adjusting these parameters within specific ranges, the invention achieves rapid charge-discharge characteristics while preventing excessive amorphous carbon from degrading high-temperature storage properties.
2Quantity of substance
If graphite particles are pressed to high density to increase capacity, then battery capacity is improved, but pressability deteriorates due to particle hardness
Solution Approach 1:
The patent introduces controlled porosity into the graphite particle structure with pore volumes of 0.03-0.15 mL/g. These pores act as compression buffers that allow particles to be densely packed during electrode manufacturing without excessive hardening. The porous structure enables high green density achievement while maintaining particle deformability under press loads.
3Quantity of substance
If electrode material is expanded to increase capacity, then battery capacity is improved, but electrode expansion increases causing structural issues
Solution Approach 1:
The patent creates a composite structure combining crystalline graphite cores with amorphous carbon coatings. The crystalline graphite provides structural stability and limits expansion, while the amorphous carbon layer accommodates volume changes during lithium insertion/extraction. This composite architecture enables high capacity while constraining overall electrode expansion.
4Productivity
If amorphous carbon content is increased to improve charge-discharge characteristics, then rapid charge characteristics are improved, but particle hardness increases reducing pressability
Solution Approach 1:
The patent optimizes the amount of amorphous carbon and pore volume parameters to achieve the desired balance. Specifically, pore volumes of 0.03-0.15 mL/g and controlled amorphous carbon content enable rapid charge characteristics while maintaining particle softness for good pressability during electrode manufacturing.
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 proposed materials achieve high capacity, excellent rapid charge-discharge characteristics, balanced low-temperature input-output and high-temperature storage characteristics, and reduced electrode expansion, enhancing battery performance.
Implementation Method 1
a graphite that contains an amorphous carbonaceous material in at least a part of the surface
Implementation Method 2
having a cumulative pore volume of 0.100 mL/g or less in a pore size range of 0.01 μm or more and 1 μm or less
Data Source
AI summary
A negative electrode raw material may be suitable for a nonaqueous secondary battery, the negative electrode material including a graphite. The negative electrode material is configured such that, when a mercury intrusion volume and a mercury extrusion volume, determined by mercury intrusion, are defined as A and B, respectively, the value of formula (1) is 45% or higher:B/A=100 (%).(1)