Silicon-Carbon Anode Material for Lithium-Ion Batteries
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Solution Overview
Problem
Silicon-based anode materials in lithium-ion batteries suffer from significant volume expansion during cycling, leading to material pulverization and rapid cycle degradation due to agglomeration, which affects the cycle stability and performance.
Innovation Solution
An anode material comprising a carbon material with silicon material dispersed within and between the carbon structure, controlled at a volume ratio of 0.9 to 2.3, and with an average distance of 3 to 50 nm between silicon particles, ensuring uniform dispersion and reduced local stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon material is used as anode material to achieve high capacity, then energy density is improved, but volume expansion during cycling causes material pulverization and rapid cycle degradation
Solution Approach 1:
The silicon material particles are embedded within the carbon material matrix, with silicon particles nested inside or between carbon particles. This nested structure allows the carbon material to constrain the silicon during volume expansion while maintaining electrical conductivity, thus improving both energy density and cycle stability
Solution Approach 2:
The patent creates a carbon-silicon composite material where carbon and silicon are combined in a specific volume ratio (0.9 ≤ Vc/Vsi ≤ 2.3). This composite structure leverages the high capacity of silicon while using carbon to provide structural stability and conductivity, resolving the contradiction between energy density and cycle stability
2Reliability
If silicon-carbon composite method is used to inhibit volume expansion, then cycle stability is improved, but silicon material agglomeration causes excessive local expansion stress
Solution Approach 1:
The patent controls the spatial distribution of silicon particles within the carbon matrix, ensuring uniform dispersion with specific distance constraints (3 ≤ d ≤ 50 nm between adjacent silicon particles). This local quality control prevents agglomeration and distributes expansion stress uniformly, avoiding excessive local stress while maintaining cycle stability
3Stability of the object's composition
If silicon material is dispersed in carbon material to improve conductivity and reduce volume expansion, then structural stability is improved, but manufacturing precision is required to control particle distance and volume ratio
Solution Approach 1:
The patent defines specific parameter ranges for the composite structure: volume ratio (0.9 ≤ Vc/Vsi ≤ 2.3) and particle distance (3 ≤ d ≤ 50 nm). By establishing these quantitative parameters, the patent transforms the manufacturing process into one with clear control targets, making it feasible to achieve uniform dispersion and optimal performance through controlled synthesis methods
Data Source
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AI summary
An anode material includes a carbon material and a silicon material, and the silicon material is located inside the carbon material and/or between the carbon material; a total volume of the carbon material is VC, and a total volume of the silicon material is VSi, wherein 0.9 ≤ VC/VSi≤2.3; a SEM section of a particle of the anode material is divided into a plurality of unit regions with an area of A × B, wherein A × B = 104nm2, an average distance between adjacent particles of the silicon material in any unit area is d nm, and 3 ≤ d ≤ 50. According to the anode material provided by the present disclosure, the dispersion uniformity of the silicon material can be improved, the volume expansion of the anode material can be effectively inhibited, and the battery cycle performance is improved.