Composite Electrode Particle Design for Lithium Battery Capacity
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Solution Overview
Problem
Rechargeable lithium batteries face capacity reduction and structural disintegration due to the expansion of high-capacity materials like silicon and metal oxides during charging and discharging, leading to a short lifespan.
Innovation Solution
A composite particle comprising a carbon matrix, active nanoparticles with a protective oxide, carbide, or nitride layer, and graphite particles, where the protective layer's volume fraction is controlled to prevent cracking and maintain high capacity and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high capacity material (silicon or metal oxide) is used to increase battery capacity, then the battery capacity is improved, but the electrode structure disintegrates due to expansion during charging and discharging
Solution Approach 1:
The active material nanoparticles are embedded within a carbon matrix, forming a nested structure where the carbon matrix provides structural support while the active material provides high capacity. This nested configuration allows the active material to expand and contract without compromising the overall electrode structure.
Solution Approach 2:
The invention uses a composite structure combining carbon matrix with active material nanoparticles (silicon or metal oxide). The carbon matrix provides structural stability and conductivity, while the active material provides high capacity, creating a composite that balances both requirements.
2Duration of action of stationary object
If the amount of high capacity material is reduced to extend battery lifespan, then the electrode structure stability is improved, but the battery capacity decreases
Solution Approach 1:
By nesting active material nanoparticles within the carbon matrix, the structure provides both longevity and high capacity. The carbon matrix ensures structural integrity for extended lifespan, while the dispersed active material nanoparticles maintain high capacity without causing structure disintegration.
3Stability of the object's composition
If protective layer volume fraction is increased to prevent structural cracks, then the electrode structure stability is improved, but the electrical conductivity decreases
Solution Approach 1:
The invention optimizes the volume fraction parameter of the protective layer, maintaining it below 23% to balance crack resistance and electrical conductivity. This parameter optimization ensures the protective layer is sufficient to prevent structural cracks while thin enough to maintain high electrical conductivity for high coulombic efficiency.
Data Source
AI summary
A composite particle for electrode includes a carbon matrix, a plurality of active nanoparticles and a plurality of graphite particles. The active nanoparticles are randomly dispersed in the carbon matrix. Each of the active nanoparticles includes an active material and a protective layer. The protective layer covers the active material, and the protective layer is an oxide, a carbide or a nitride of the active material. The graphite particles are randomly dispersed in the carbon matrix. A volume fraction of the protective layer in each of the active nanoparticles is smaller than 23.0%.