Binderless Graphite Anode Material for Fast-Charging Cycle Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in high temperature performance and fast charging characteristics, particularly in maintaining electrode structure stability and minimizing internal pore volume changes during rolling, which affects their cycle life and energy density.
Innovation Solution
A binderless negative electrode material is developed using green cokes with high organic volatile matter content, assembled through self-assembly by heating and kneading primary particles without a binder, followed by graphitization, to enhance the material's affinity and adhesion properties, thereby improving high temperature characteristics and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a binder is used to assemble carbon particles in negative electrode material, then adhesion and structural integrity are improved, but internal pore volume increases and high temperature performance deteriorates
Solution Approach 1:
The invention removes the binder component from the negative electrode material composition entirely. By extracting the binder function and replacing it with organic volatile matter inherently present in green coke, the patent eliminates the trade-off between adhesion and high temperature performance, achieving both strong bonding and excellent thermal stability without internal pore volume increase.
Solution Approach 2:
The invention changes the chemical composition parameters by using green coke with high organic volatile matter content (15-35 wt%) instead of conventional low-volatile cokes combined with binder. This parameter change in volatile matter content enables self-bonding behavior during heating, achieving adhesion without binder while maintaining structural integrity at high temperatures.
2Stability of the object's composition
If conventional cokes with low organic volatile matter are used, then structural stability is achieved, but adhesion and bonding properties are insufficient
Solution Approach 1:
The invention inverts the conventional approach by selecting cokes with high organic volatile matter content (15-35 wt%) instead of low volatile matter. This parameter reversal enables the volatile matter to act as a bonding agent during heating, providing strong adhesion while the subsequent graphitization process ensures structural stability, eliminating the need to choose between stability and adhesion.
3Ease of manufacture
If green coke with high organic volatile matter is used and heated, then self-assembly and adhesion occur without binder, but process control complexity increases
Solution Approach 1:
The invention enables self-service by utilizing the organic volatile matter naturally present in green coke (15-35 wt%) to perform the bonding function that would otherwise require added binders. During heating to 300-700°C, the volatile matter evaporates and condenses to bond carbon particles together, creating a binderless structure. This self-bonding mechanism simplifies manufacturing by eliminating binder addition steps while the controlled heating process ensures reproducible results.
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 binderless method allows for efficient assembly and retention of organic volatile matter, resulting in a negative electrode active material with improved high temperature performance, increased cycle life, and enhanced energy density, suitable for fast-charging applications in lithium secondary batteries.
Implementation Method 1
heating and kneading the primary particles to assemble them into a secondary particle
Implementation Method 2
applying high heat energy of more than 2,700° C. to create the crystal structure of graphite
Data Source
AI summary
A present disclosure is related to a method of manufacturing a negative electrode active material for lithium secondary battery:preparing a primary particle by grinding a carbon source containing 10 to 25 wt % volatile matter; heating and kneading the primary particle to assemble them into a secondary particle; and graphitizing the secondary particle; wherein, the step of assembling the secondary particle is the step of heating and kneading only the primary particle without adding a binder. In addition, it is provided a negative electrode active material for a lithium secondary battery has a retention of 80% discharge capacity of 20 cycles or more.