Silicon Nanoparticle Anode Material With Low-Impurity Size Control
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Solution Overview
Problem
Existing methods for preparing silicon nanoparticles for use as an anode active material in secondary batteries face challenges such as high impurity content, high processing costs, and inefficient particle size control, which affect battery performance.
Innovation Solution
A method involving dry-pulverizing and wet-pulverizing polysilicon fine powders to produce silicon nanoparticles with controlled particle sizes (80 nm < D50 < 150 nm) and low impurity content (200 ppm or lower metal impurities and 10.0% or lower oxygen content).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal silicon is used as raw material, then processing cost is reduced, but impurity content increases making it difficult to achieve low metal impurity levels
Solution Approach 1:
The patent performs preliminary classification of polysilicon raw materials by purity level before processing. High-purity polysilicon (99.999% or higher) is selected and processed separately to ensure low impurity content in the final nanoparticles, while accepting higher costs for this premium raw material grade.
2Manufacturing precision
If silicon kerf is used as raw material, then purity is high, but contamination with lubricants and water occurs during cutting process
Solution Approach 1:
The patent extracts and removes contaminants from the silicon raw material through a classification process. By sorting polysilicon based on purity levels and selecting only high-purity material, the harmful contaminants introduced during cutting (lubricants, water, oxidation) are excluded from the processing stream.
3Ease of manufacture
If polysilicon chunks or chips are used, then raw material cost is high, but initial particle size is too large requiring multiple pulverizing steps
Solution Approach 1:
The patent performs preliminary size classification of polysilicon raw materials into fine powder form (0.2-0.5 mm particle size) before nanoparticle production. This pre-grinding step reduces the initial particle size, allowing single-stage high-energy pulverization to achieve the target 80-150 nm nanoparticle size without requiring multiple sequential grinding steps.
4Reliability
If graphite-based material is used as anode, then electrochemical performance is excellent and cost is low, but theoretical capacity is limited to 370 mAh/g
Solution Approach 1:
The patent creates a composite anode material system combining silicon nanoparticles (4000-4200 mAh/g theoretical capacity) with carbon materials. The silicon provides high capacity while the carbon matrix accommodates volume expansion and maintains structural integrity, achieving both high capacity and good electrochemical performance simultaneously.
5Reliability
If silicon nanoparticles are produced with high purity requirements, then battery performance improves, but processing costs increase
Solution Approach 1:
The patent performs preliminary classification of polysilicon raw materials by purity level before processing. High-purity polysilicon (99.999% or higher) is selected and processed separately to ensure low impurity content in the final nanoparticles, while accepting higher costs for this premium raw material grade.
Solution Approach 2:
The patent changes the key parameter of raw material purity specification from standard industrial grade to ultra-high purity (99.999% or higher). This parameter change ensures that impurity levels in the final nanoparticles remain below critical thresholds, guaranteeing battery performance while establishing a clear quality standard.
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 efficiently produces high-purity silicon nanoparticles that improve the initial discharge capacity, initial efficiency, and cycle life characteristics of secondary batteries, while reducing processing costs.
Implementation Method 1
dry-pulverizing and wet-pulverizing polysilicon fine powders to prepare silicon nanoparticles
Data Source
AI summary
The present invention relates to a method for efficiently producing silicon nanoparticles having a controlled particle size, with a minimal content of impurities such as metal and oxygen. Specifically, the present invention may provide a method for producing silicon nanoparticles, wherein polysilicon fine powder is used as a raw material, whereby the silicon nanoparticles have particle sizes of 80 nm<D50<150 nm and 100 nm<D90<250 nm, a total metal impurity content of 200 ppm or less, and a total oxygen content of 10.0% or less.