Silicon-Carbon Anode Composite for Stable Battery Slurry
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Solution Overview
Problem
Silicon carbon composites exhibit low phase stability during the preparation and storage of negative electrode slurries in lithium secondary batteries, limiting their performance.
Innovation Solution
A silicon carbon composite with controlled silicon and carbon ratios (C/Si) and oxygen content, optimized through specific etching times and conditions, is used to enhance phase stability and reduce oxidation reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon is used as negative electrode material to increase capacity, then energy density is improved, but phase stability during slurry preparation and storage deteriorates
Solution Approach 1:
The patent uses a composite material structure where silicon particles are embedded in a carbon matrix. This composite design allows the silicon to provide high capacity while the carbon matrix maintains structural integrity and phase stability during slurry preparation and storage, resolving the contradiction between energy density improvement and phase stability maintenance.
Solution Approach 2:
The patent optimizes specific parameters including silicon content (40-60 wt%), oxygen content (≤10 wt%), and C/Si ratio (15-30) to achieve the desired balance. By carefully controlling these compositional parameters, the material achieves both high energy density from silicon and adequate phase stability through the carbon-rich composition.
2Quantity of substance
If silicon content is increased to improve capacity, then initial capacity is improved, but oxidation reactions increase
Solution Approach 1:
The carbon matrix acts as an intermediary barrier between silicon and the environment. This carbon layer prevents direct contact between silicon and water/oxygen, thereby suppressing oxidation reactions while still allowing the silicon to contribute its high capacity to the electrode.
Solution Approach 2:
The high carbon content (60-80 wt%) creates a chemically inert environment around the silicon particles. This carbon-rich composition effectively creates an inert atmosphere that protects the reactive silicon from oxidation during storage and processing.
3Stability of the object's composition
If carbon content is increased to improve phase stability, then slurry stability is improved, but energy density decreases
Solution Approach 1:
The patent optimizes the carbon content to a specific range (60-80 wt%) that provides sufficient phase stability and slurry stability while maintaining adequate energy density. This parameter optimization ensures that the carbon provides structural stability without excessively diluting the high-capacity silicon content.
Solution Approach 2:
The composite structure allows carbon to provide stability functions while silicon provides capacity functions. The synergistic combination ensures that carbon's stabilizing effect does not come at the prohibitive cost of reduced energy density, as the silicon particles maintain their high capacity contribution within the carbon matrix.
4Stability of the object's composition
If oxygen content is reduced to suppress oxidation reactions, then phase stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies a clear target parameter (oxygen content ≤10 wt%) that guides the manufacturing process. By focusing on this single compositional parameter, the manufacturing process becomes more controllable and less complex, as producers can optimize their processes to meet this specific oxygen content target without managing multiple conflicting parameters.
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 provides a negative electrode with high capacity and efficiency by limiting Si-water contact and suppressing gas generation, ensuring stable slurry performance.
Implementation Method 1
suppress oxidation reactions, thereby reducing the amount of hydrogen gases generated
Data Source
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AI summary
The present invention relates to: a silicon carbon composite; a negative electrode composition, a negative electrode, a lithium secondary battery, a battery module, a battery pack, and an electric vehicle comprising same; and a method for manufacturing the silicon carbon composite, wherein the silicon carbon composite comprises silicon and carbon, the content of silicon is 40 to 60 parts by weight with respect to 100 parts by weight of the silicon carbon composite, the content ratio (C/Si) of carbon to silicon is 30 or more after 10 seconds of etching time under the condition of Ta205 being etched at a rate of 0.15 nm/s during XPS analysis and is less than or equal to 15 after 1,000 seconds of etching time, and the oxygen content is less than or equal to 10 parts by weight with respect to 100 parts by weight of the silicon carbon composite.