Silicon-Carbon Anode Material Using Opposite Surface Charges
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Solution Overview
Problem
The agglomeration of silicon-based materials in secondary batteries leads to uneven particle distribution, excessive expansion, and reduced rate performance, posing safety and performance issues due to their high volume expansion and polarization compared to graphite.
Innovation Solution
A negative electrode active material is developed with a carbon-based material and a silicon-based material, where functional groups with opposite charges are introduced on their surfaces to prevent agglomeration, ensuring uniform distribution and improved dispersion, thereby enhancing the battery's rate performance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used to replace graphite, then specific capacity and energy density are improved, but volume expansion and particle agglomeration occur, deteriorating kinetics and rate performance
Solution Approach 1:
The silicon-based material particles are embedded within the carbon-based material particles, forming a core-shell structure where silicon is nested inside carbon. This prevents volume expansion of silicon from causing particle agglomeration, as the carbon shell accommodates the expansion while maintaining overall particle integrity and uniform distribution in the electrode.
Solution Approach 2:
The invention creates a composite particle system where silicon-based material and carbon-based material are combined at the particle level. The carbon-based material serves as both the structural framework and the matrix embedding silicon particles, creating a composite that leverages the high capacity of silicon while mitigating its expansion issues through the stable carbon structure.
2Quantity of substance
If silicon-based materials are simply mixed with carbon-based materials, then high silicon content can be achieved, but particle agglomeration occurs leading to uneven distribution and reduced rate performance
Solution Approach 1:
Silicon-based material particles are nested within carbon-based material particles, creating a hierarchical structure that prevents agglomeration. The embedding approach ensures that even at high silicon content, particles remain individually dispersed within the carbon matrix, maintaining uniform distribution throughout the electrode.
Solution Approach 2:
The carbon-based material is designed with different local properties: the outer shell provides structural stability and prevents agglomeration, while the inner region accommodates silicon particles. This local differentiation allows high silicon content while maintaining overall particle stability and uniform distribution.
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 use of oppositely charged functional groups on the carbon and silicon materials effectively prevents agglomeration, balances capacity and rate performance, and improves the overall stability and performance of the battery, particularly in high-silicon content systems.
Implementation Method 1
a first functional group exists on the surface of the carbon-based material, a second functional group exists on the surface of the silicon-based material, and the first functional group has a charge opposite to that of the second functional group
Data Source
AI summary
A negative electrode active material comprises a carbon-based material and a silicon-based material, wherein a first functional group exists on the surface of the carbon-based material, a second functional group exists on the surface of the silicon-based material, and the first functional group has a charge opposite to that of the second functional group.