Amorphous Silicon Monoxide Powder via Gas-Phase Oxidation
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Solution Overview
Problem
Current methods for producing silicon monoxide (SiO) are inefficient, particularly in achieving an amorphous state with a low disproportional rate, which is essential for its application as a negative electrode active material in lithium-ion secondary batteries, due to limitations in reaction temperature and powder contact points in conventional solid-phase reactions.
Innovation Solution
A silicon monoxide powder is produced by oxidizing metal silicon powder using the reaction heat of oxygen gas and a flammable gas in an air stream, controlling the oxidation reaction to maintain the SiO in an amorphous state with a composition ratio of SiOx between 0.8 and 1.2, and coating it with a conductive film for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reaction temperature is increased to promote the solid-phase reaction between Si and SiO2 powders, then the reaction speed improves, but metal silicon Si melts and becomes difficult to retain
Solution Approach 1:
The invention utilizes the phase transition of SiO from solid to gas state at high temperature (sublimation around 1500°C) to separate the reaction product from the reactants. By controlling the temperature to maintain SiO in gas phase and then rapidly cooling it, the product is obtained without melting the metal silicon reactants, thus resolving the contradiction between reaction speed and material retention.
Solution Approach 2:
The invention changes the physical state parameters of the reaction system by introducing a gas-phase intermediate (SiO gas) between solid reactants. This parameter change allows the reaction to proceed at high temperature without the reactants melting, as the product immediately vaporizes and can be separated by cooling, thus maintaining both high reaction speed and reactant integrity.
2Productivity
If fine powders are used to increase contact points between Si and SiO2, then the reaction efficiency improves, but the cost for pulverization equipment and energy increases
Solution Approach 1:
The invention extracts the product SiO from the solid-phase reaction system in gas form, allowing the use of coarser reactant powders. By taking out the product as gas, the need for extreme fine pulverization of reactants is reduced, as the gas-phase separation mechanism compensates for lower contact points, thus reducing pulverization costs while maintaining reaction efficiency.
Solution Approach 2:
The invention introduces a pneumatic element by utilizing the gas phase of SiO as an intermediate. The gaseous SiO carries the reaction progress information and allows product removal without requiring the reactants to be in fine powder form, thus reducing the mechanical pulverization requirements and associated costs.
3Productivity
If the Si powder is excessively fine to increase contact points, then the reaction promotes, but the powder surface is easily oxidized and dust explosion risk increases
Solution Approach 1:
The invention uses the phase transition of SiO to gas at reaction temperature to quickly remove the product from the reaction zone. This prevents excessive fine Si powder from being exposed to oxidizing conditions for extended periods, as the SiO product immediately vaporizes, reducing the window for unwanted oxidation and dust explosion risks associated with fine powder handling.
Solution Approach 2:
The invention rushes the SiO product through the high-temperature zone in gas form, quickly transporting it away from the reactant mixture. This rapid transit prevents the fine Si powder from undergoing unwanted side reactions like oxidation, and minimizes the time fine powders are present in a reactive state, thereby reducing dust explosion risks.
4Productivity
If strong pressure is applied to increase contact points between Si and SiO2 powders, then the reaction improves, but both materials are ceramics and not deformable, limiting the pressure effect
Solution Approach 1:
The invention bypasses the need for mechanical deformation and increased contact points by transitioning the product SiO to gas phase. This eliminates the requirement for strong pressure to create contact points, as the gaseous product can form and separate without requiring intimate contact between the ceramic particles, thus resolving the limitation imposed by ceramic deformability.
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
This method efficiently produces SiO powder with a low disproportional rate, enhancing its suitability as a high-capacity negative electrode material for lithium-ion batteries, with improved initial efficiency and cycle characteristics when used in lithium-ion secondary batteries.
Implementation Method 1
a silicon monoxide (SiO) powder comprising silicon monoxide (SiO), in which in an X-ray diffraction spectrum of the silicon monoxide (SiO) powder measured by X-ray diffraction by using a Cu-Kα ray, broad peaks due to an amorphous state are near 2θ=22° and near 2θ=50°
Implementation Method 2
oxidizing a metal silicon (Si) powder by using a reaction heat of oxygen gas with a flammable gas in an air stream as an energy source
Implementation Method 3
oxidizing a metal silicon (Si) powder by using a reaction heat of oxygen gas with a flammable gas in an air stream as an energy source
Implementation Method 4
SiO is directly sublimated by a contact reaction between powders to become SiO gas, basically without passing through a liquid phase. The SiO gas is deposited onto a deposition plate or the like, cooled, and then solidified to become bulk SiO
Data Source
AI summary
A silicon monoxide powder including silicon monoxide, in which in an X-ray diffraction spectrum of the silicon monoxide powder measured by X-ray diffraction by using a Cu-Kα ray, broad peaks due to an amorphous phase are near 2θ=22° and near 2θ=50°, and a peak due to a crystal phase of silicon is not near 2θ=28°.