Composite Silicon Oxide Anode Material for Volume Expansion Control
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Solution Overview
Problem
Silicon-based active materials in lithium secondary batteries face issues with volume expansion and contraction during charging and discharging, leading to damage and reduced service life due to their high capacity and energy density.
Innovation Solution
A composite negative electrode active material is developed, comprising silicon-based oxide particles with a metal (Li, Mg, or Al) distributed on their surface or inside, with an average aggregate diameter of 65 nm or less, to minimize volume expansion and enhance service life performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active materials are used to achieve high capacity and energy density, then the battery capacity increases about 10-fold compared to carbon-based materials, but volume expansion during charging and discharging causes cracks and damage to active material particles
Solution Approach 1:
The patent creates a composite structure where silicon-based oxide particles are embedded within a carbon matrix. This composite approach allows the silicon to provide high capacity while the carbon matrix constrains volume expansion and prevents particle damage during charging-discharging cycles, thereby maintaining both high capacity and long service life
Solution Approach 2:
The carbon matrix acts as a flexible shell surrounding the silicon-based oxide particles. This shell accommodates the volume changes of silicon during lithiation and delithiation while maintaining structural integrity, preventing cracks and damage to the active material particles
2Use of energy by moving object
If silicon-based active materials are used to achieve high energy density with thin electrodes, then the battery becomes lightweight and compact, but volume expansion causes cracks and damage to active material particles
Solution Approach 1:
The composite of silicon-based oxide particles within a carbon matrix provides both high energy density and mechanical strength. The carbon matrix reinforces the structure to prevent particle damage while the silicon phases provide high capacity for energy storage
3Quantity of substance
If volume expansion of silicon-based active materials is not controlled, then high capacity is achieved, but cracks and damage occur leading to deterioration in service life characteristics
Solution Approach 1:
The carbon matrix serves as a flexible shell that accommodates volume expansion of the silicon-based oxide particles during charging. This flexible constraint allows capacity utilization while preventing structural failure that would limit service life
Data Source
AI summary
A composite negative electrode active material including silicon-containing oxide particles; and a metal distributed on the surface, inside, or both on the surface and inside of the silicon-containing oxide particles, in which an average value of aggregate diameters measured by a specific method is 65 nm or less. The composite negative electrode active material can have a uniform and small aggregate diameter to minimize deterioration of service life performance of the composite negative electrode active material caused by volume expansion and contraction of silicon during charging and discharging.