Silicon Particle Surface Oxidation for Aqueous Anode Stability
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Solution Overview
Problem
Rechargeable lithium-ion batteries face challenges with silicon anode production due to silicon's reactivity with water, leading to hydrogen formation, inhomogeneous electrode coatings, and reduced battery capacity, especially with larger particle sizes and aggregated silicon particles.
Innovation Solution
Treating nonaggregated silicon particles with an oxygen-containing gas at elevated temperatures to produce nonaggregated, modified silicon particles with low hydrogen evolution, suitable for use in aqueous ink formulations, resulting in homogeneous anode coatings and high silicon proportions in lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used in aqueous ink formulations, then high silicon capacity can be achieved, but hydrogen formation occurs due to oxidation of silicon surface by water
Solution Approach 1:
A protective coating layer is applied to the silicon particle surface to act as an intermediary barrier between the silicon and water. This coating prevents direct contact and oxidation reactions, eliminating hydrogen formation while allowing the silicon to maintain its high capacity functionality in aqueous ink formulations.
Solution Approach 2:
The oxidation reaction that originally caused harm (hydrogen formation) is converted into a beneficial protective oxide layer on the silicon surface. This layer passivates the surface, preventing further harmful oxidation reactions with water while maintaining the electrical and electrochemical functionality of the silicon.
2Reliability
If silicon particles are oxidized to reduce hydrogen formation, then process safety improves, but silicon proportion in anode decreases reducing battery capacity
Solution Approach 1:
Oxidation is applied locally only to the surface layer of the silicon particles rather than bulk oxidation. This creates a thin protective oxide skin that provides safety benefits while preserving the majority of the silicon core material, maintaining high silicon proportion and battery capacity.
Solution Approach 2:
Partial oxidation is performed to achieve just enough surface passivation to eliminate hydrogen formation risks, without excessive oxidation that would consume too much silicon. The oxidation is controlled to reach the minimum necessary level for safety while preserving maximum silicon content.
3Ease of manufacture
If larger particle sizes are used for silicon, then manufacturing complexity reduces, but Coulomb efficiency decreases
Solution Approach 1:
The particle size parameters are optimized to a specific range that balances manufacturability and performance. By carefully controlling particle size within defined boundaries, the patent achieves both ease of manufacture and high Coulomb efficiency, resolving the contradiction between these two parameters.
4Ease of operation
If silicon particles are aggregated, then handling and processing becomes easier, but anode coating homogeneity deteriorates
Solution Approach 1:
The patent uses non-aggregated individual particles instead of aggregated clusters. This segmentation allows each particle to be independently dispersed and distributed uniformly in the aqueous ink, ensuring homogeneous anode coating while maintaining ease of handling through proper particle size and surface properties.
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 modified silicon particles significantly reduce hydrogen formation, allowing for stable and homogeneous anode coatings with high silicon content, enhancing the electrochemical performance and cycle stability of lithium-ion batteries while maintaining high energy densities.
Implementation Method 1
treating nonaggregated silicon particles with an oxygen-containing gas at 80° C. to 900° C.
Implementation Method 2
at elevated temperature
Data Source
AI summary
The invention relates to methods for producing non-aggregated, modified silicon particles by treating non-aggregated silicon particles which have volume-weighted particle size distributions with diameter percentiles d50 of 1.0 μm to 10.0 μm at 80° C. to 900° C. with an oxygen-containing gas.