Graphite Anode Composite With Conductive-Filled Gaps for Cycle-Life
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Solution Overview
Problem
Rechargeable lithium batteries using graphite and silicon mixtures face challenges in suppressing volume changes of silicon, leading to a sharp drop in initial cycle-life and capacity, and existing methods to enhance binder and conductive material content increase costs or deteriorate efficiency and cycle-life.
Innovation Solution
A negative electrode active material composite is developed, comprising artificial graphite primary particles assembled with a conductive material and an amorphous carbon coating layer, which are manufactured by assembling artificial graphite particles with a conductive material and an amorphous carbon precursor, and carbonizing the product, to improve adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If binder and conductive material content is increased to suppress silicon volume changes, then adhesion and conductivity are improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by coating amorphous carbon specifically on the surface of artificial graphite primary particles rather than uniformly mixing conductive materials throughout. This localized coating approach improves adhesion at critical interfaces while minimizing the overall amount of conductive material needed, thereby reducing manufacturing costs while maintaining reliable adhesion.
Solution Approach 2:
The patent creates a composite structure where artificial graphite primary particles are coated with amorphous carbon and assembled into secondary particles with conductive material in internal gaps. This composite approach enhances both adhesion and conductivity through the synergistic combination of different materials (artificial graphite, amorphous carbon, and conductive material) in a structured configuration, achieving improved performance without proportionally increasing material costs.
2Speed
If binder and conductive material content is increased to enhance conductivity, then charging rate is improved, but manufacturing cost increases
Solution Approach 1:
The amorphous carbon coating is applied locally on the surface of artificial graphite primary particles, creating high-conductivity pathways at critical interfaces where electron transfer occurs. This localized approach maximizes conductivity enhancement at the particle level without requiring uniform distribution of expensive conductive materials throughout the entire electrode, thus improving charging rate while controlling manufacturing costs.
Solution Approach 2:
The patent utilizes the internal gaps within secondary particles as a three-dimensional space to position conductive material, creating conductivity pathways in multiple dimensions. This spatial arrangement enhances electron transport efficiency and charging rate by providing conductive networks throughout the particle structure, while the controlled placement reduces the total amount of conductive material required compared to uniform mixing approaches.
3Quantity of substance
If silicon content is increased to obtain higher capacity, then theoretical capacity is improved, but volume change increases leading to sharp drop in initial cycle-life
Solution Approach 1:
The amorphous carbon coating acts as a flexible protective shell on the artificial graphite primary particles. This thin film structure accommodates volume changes during lithium insertion/extraction cycles while maintaining structural integrity and adhesion. The coating prevents particle fragmentation and maintains electrical contact during cycling, thereby preserving both high capacity and good initial cycle-life performance.
Solution Approach 2:
The patent employs a composite structure combining artificial graphite primary particles with amorphous carbon coating and conductive material in internal gaps. This composite design provides mechanical support and maintains conductivity even when silicon undergoes volume changes during cycling. The multi-material composite structure mitigates the harmful effects of silicon expansion while preserving high capacity, achieving both improved theoretical capacity and maintained initial cycle-life.
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 composite prevents a sharp drop in initial cycle-life while securing long-term cycle-life and initial discharge capacity, enhancing the conductive network and adhesion, thus maintaining high charging rates and cycle-life without increasing costs.
Implementation Method 1
assembling artificial graphite primary particles in the presence of a conductive material and an amorphous carbon precursor, and forming the amorphous carbon coating layer from the amorphous carbon precursor
Data Source
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AI summary
A negative electrode active material composite, a method of manufacturing the same, a negative electrode including the same, and a rechargeable lithium battery are described. The negative electrode active material composite includes secondary particles in which artificial graphite primary particles are assembled; and a conductive material in internal gaps of the secondary particles; wherein at least some of the artificial graphite primary particles include an amorphous carbon coating layer on a surface thereof.