Passivated Silicon Nanoparticles to Limit Oxide Formation in Anodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for synthesizing silicon nanoparticles using induction plasma torches result in particles with reactive surfaces prone to oxide layer formation, leading to performance degradation in lithium-ion batteries due to insulating SiOx layers and hydrogen gas production.
Innovation Solution
A method involving an induction plasma torch with a quenching zone using a passivating gas precursor to form a passivation layer in situ on silicon or alloy nanoparticles, reducing reactivity with oxygen and moisture, and optionally coating with conductive carbon to maintain electrical pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional induction plasma torch methods are used to synthesize silicon nanoparticles, then the production process is simple and fast, but the nanoparticles form reactive surfaces prone to oxide layer formation leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by introducing a passivating gas precursor into the quenching zone before the nanoparticles are fully formed and cooled. This allows the passivation layer to be formed in situ during the synthesis process, preventing oxide layer formation from the outset rather than requiring subsequent treatment steps.
Solution Approach 2:
The patent uses a passivating gas precursor as an intermediary substance that mediates between the reactive silicon nanoparticle surface and oxygen/moisture in the environment. This intermediary forms a protective passivation layer that prevents direct contact between the reactive nanoparticle surface and harmful environmental factors.
2Reliability
If passivation layers are deposited by atomic layer deposition (ALD) to protect silicon nanopowder surfaces, then oxide formation is prevented, but the process requires multiple steps and additional equipment
Solution Approach 1:
The patent merges the nanoparticle synthesis process with the passivation process by introducing the passivating gas precursor into the quenching zone of the plasma reactor. This combines two previously separate operations (synthesis and passivation) into a single integrated process, eliminating the need for separate ALD equipment and multiple processing steps.
Solution Approach 2:
The patent applies self-service by designing the plasma reactor system to automatically form the passivation layer during the nanoparticle synthesis process itself. The system uses its own quenching zone and gas delivery mechanisms to provide passivation, eliminating the need for external passivation equipment and processes.
3Reliability
If silicon nanopowder surfaces are protected from oxide formation, then battery performance is improved, but electrical conductivity may be reduced by insulating layers
Solution Approach 1:
The patent applies parameter changes by carefully controlling the type, concentration, and exposure time of the passivating gas precursor to form a passivation layer with optimal properties. By adjusting these parameters, the system achieves a balance between protection and conductivity, forming a thin enough layer to maintain electrical contact while thick enough to prevent oxidation.
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 method produces nanoparticles with reduced oxide formation, improved cycle performance, and stable electrical conductivity, enhancing the performance and safety of silicon anodes in lithium-ion batteries by preventing undesirable reactions and maintaining conductivity.
Implementation Method 1
providing a plasma reactor comprising an induction plasma torch generating a plasma at a temperature allowing production of a vapor of the silicon or alloy thereof from the core precursor
Implementation Method 2
induction plasma torch generating a plasma
Implementation Method 3
the quenching zone being cooled down by a quenching gas to a temperature allowing condensation of the vapor
Implementation Method 4
the quenching zone being cooled down by a quenching gas
Implementation Method 5
the quenching gas comprises a passivating gas precursor that reacts with the surface of the core in the quenching zone to produce the passivation layer covering the core
Data Source
AI summary
There is provided a method of manufacturing nanoparticles comprising the steps of feeding a core precursor into a plasma torch in a plasma reactor, thereby producing a vapor of silicon or alloy thereof; and allowing the vapor to migrate to a quenching zone of the plasma reactor, thereby cooling the vapor and allowing condensation of the vapor into a nanoparticle core made of the silicon or alloy thereof, wherein the quenching gas comprises a passivating gas precursor that reacts with the surface of the core in the quenching zone produce a passivation layer covering the core, thereby producing said nanoparticles. The present invention also relates to nanoparticles comprising a core covered with a passivation layer, the core being made of silicon or an alloy thereof, as well as their use, in particular in the manufacture of anodes.