Silicon-Based Active Material Particles for Secondary Battery
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Solution Overview
Problem
Silicon-based negative electrode materials for lithium secondary batteries face challenges due to volume expansion during charging and discharging, leading to reduced service life and irreversible reactions, which hinder their commercialization.
Innovation Solution
A method involving the refinement of silicon powders using mechanical compression and shearing stress, followed by the formation of a chemical oxidation layer using an oxidant solvent, to create silicon-based active material particles with controlled circularity and oxygen content, thereby minimizing volume change and enhancing service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If silicon particles are made to nano particles to minimize volume expansion and contraction, then service life is improved, but particle refinement due to repeated volume expansion/shrinkage causes rapid deterioration of service life
Solution Approach 1:
The silicon particle is segmented into a core-shell structure where the core is silicon and the shell is a protective layer. This segmentation allows the silicon core to undergo volume expansion/contraction while the shell protects against particle refinement and maintains structural integrity over repeated cycles.
Solution Approach 2:
A protective shell is formed beforehand on the silicon particle surface to cushion and absorb the mechanical stress from volume expansion and contraction during charging/discharging cycles, preventing particle refinement and maintaining service life.
2Quantity of substance
If silicon-based material is used to achieve high capacity of 500 mAh/g or higher, then energy density is improved, but volume increases by four times during charging causing destruction of electrical connection and irreversible reactions
Solution Approach 1:
The silicon particle is divided into a core-shell structure where the core provides high capacity and the shell accommodates and protects against volume expansion, allowing the particle to maintain electrical connection during charging/discharging cycles.
Solution Approach 2:
A flexible protective shell is formed on the silicon particle surface that can accommodate the four-fold volume expansion during charging while maintaining structural integrity and electrical connection, preventing destruction of the electrode structure.
3Manufacturing precision
If mechanical compression and shearing stress is applied to refine silicon powders, then particle size is reduced and circularity is controlled, but manufacturing complexity increases
Solution Approach 1:
The particle refinement process combines mechanical compression and shearing stress applications into a single integrated manufacturing step, achieving controlled circularity and particle size while avoiding the need for multiple separate processing stages.
4Duration of action of stationary object
If chemical oxidation layer is formed on silicon particles using oxidant solvent, then service life is extended by stabilizing solid electrolyte interface, but irreversible capacity is reduced
Solution Approach 1:
The thickness and composition of the chemical oxidation layer are precisely controlled by adjusting oxidant solvent parameters, creating an optimal layer thickness that provides sufficient protection to stabilize the solid electrolyte interface while minimizing the volume occupied by the inactive oxidation layer, thus reducing irreversible capacity loss.
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 results in silicon-based active material particles with improved energy density, reduced irreversible capacity, and extended service life by stabilizing the solid electrolyte interface and minimizing tensile hoop stress, thus enhancing the performance and durability of silicon-based electrodes.
Implementation Method 1
forming a chemical oxidation layer on the refined silicon particles by using the oxidant solvent
Implementation Method 2
forming silicon particles by refining the silicon powders of the pre-pulverization mixture by applying mechanical compression and shearing stress
Implementation Method 3
applying mechanical compression and shearing stress to the silicon powders
Implementation Method 4
yielding the silicon-based active material particles by drying a result product including the silicon-based active material particles
Data Source
AI summary
The present invention relates to a method for preparing silicon-based active material particles for a secondary battery and silicon-based active material particles. The method for preparing silicon-based active material particles according to an embodiment of the present invention comprises the steps of: providing silicon powder; dispersing the silicon powder into an oxidant solvent to provide a mixture prior to grinding; fine-graining the silicon powder by applying mechanical compression and shear stress to the silicon powder in the mixture prior to grinding to produce silicon particles; producing a layer of chemical oxidation on the fine-grained silicon particles with the oxidant solvent while applying mechanical compression and shear stress to produce silicon-based active material particles; and drying the resulting product comprising the silicon-based active material particles to yield silicon-based active material particles.