Silicon Anode Nanoparticles With In-Situ Plasma Passivation
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Solution Overview
Problem
Conventional methods for synthesizing silicon nanoparticles using induction plasma torches result in surface contamination and the formation of undesirable oxide layers, which affect their reactivity and performance in lithium-ion batteries, leading to reduced electrical conductivity and capacity.
Innovation Solution
A method involving an induction plasma torch with a quenching zone where a passivating gas precursor forms a nitride or amorphous carbon passivation layer in situ on the nanoparticles, reducing their reactivity with oxygen and moisture and preventing oxide layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional induction plasma torch synthesis is used to produce silicon nanoparticles, then the nanoparticles can be manufactured, but surface contamination and oxide layer formation occur which reduce electrical conductivity and battery performance
Solution Approach 1:
The patent applies inert atmosphere by introducing a passivating gas (argon or nitrogen) into the plasma reactor during nanoparticle synthesis. This inert or weakly reactive gas creates a protective environment that prevents oxygen and moisture from contacting the hot silicon nanoparticle surfaces, thereby preventing oxide layer formation and surface contamination while maintaining high electrical conductivity and battery performance
Solution Approach 2:
The patent implements preliminary action by forming the passivation layer on the nanoparticle surfaces during the synthesis process itself, before the particles are exposed to ambient air or moisture. The passivating gas is introduced concurrently with nanoparticle formation in the plasma reactor, ensuring that the protective layer is established prior to any potential oxidation or contamination events
2Reliability
If passivation layer is deposited by atomic layer deposition (ALD) using trimethyl aluminum, then silicon nanopowder surfaces are protected from oxidation, but the process requires separate equipment and additional processing steps
Solution Approach 1:
The patent merges the nanoparticle synthesis process with the passivation process by introducing the passivating gas directly into the plasma reactor during synthesis. This combines two previously separate operations (nanoparticle production and surface passivation) into a single integrated process, eliminating the need for separate ALD equipment and additional processing steps while achieving the same protective effect
Solution Approach 2:
The patent applies self-service by enabling the nanoparticle synthesis system to provide its own passivation function through the passivating gas. The plasma reactor itself becomes self-sufficient for both nanoparticle production and surface protection, eliminating dependence on external ALD processing and reducing overall process complexity
3Productivity
If quenching gas is used to condense vapor into nanoparticles, then condensation is achieved, but without passivation the particles remain reactive to oxygen and moisture
Solution Approach 1:
The patent applies universality by using the passivating gas to perform multiple functions simultaneously: it acts as a quenching medium to cool and condense the silicon vapor into nanoparticles, and concurrently serves as a protective atmosphere that prevents oxidation and moisture absorption. This single gas stream accomplishes both condensation and passivation tasks that would otherwise require separate systems
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 improved stability and performance in lithium-ion batteries by preventing oxide layer formation and maintaining electrical conductivity, enhancing cycle performance and reducing irreversible capacity.
Implementation Method 1
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
the quenching zone being cooled down by a quenching gas to a temperature allowing condensation of the vapor
Implementation Method 3
allowing the vapor to migrate to the quenching zone, thereby cooling the vapor and allowing condensation of the vapor into the core made of the silicon or alloy thereof
Implementation Method 4
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.