Silicon Oxide Anode Particle Distribution for Longer Li-Ion Cycle Life
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Solution Overview
Problem
Si-based negative electrode active materials for lithium secondary batteries face challenges due to volume expansion during lithium absorption and desorption, leading to cracking, poor contact, and reduced cycle life.
Innovation Solution
A negative electrode active material comprising silicon oxide particles with a full width at half maximum (FWHM) peak ranging between 2 and 6 and an average particle size (D50) of 1 to 20 μm, optimized through particle size distribution adjustment using an air classifying mill, and potentially doped with lithium, magnesium, calcium, or aluminum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si-based negative electrode active material is used to achieve high capacity, then battery capacity is improved, but volume expansion causes cracking and separation resulting in shorter cycle life
Solution Approach 1:
The patent changes the chemical composition parameter of the negative electrode material from pure silicon to silicon oxide (SiOx where 0 < x ≤ 2), which fundamentally alters the volume expansion behavior during lithium insertion/extraction cycles, thereby resolving the contradiction between achieving high capacity and maintaining cycle life
Solution Approach 2:
The patent uses silicon oxide as a composite material that combines the high capacity advantage of silicon-based materials with the structural stability of oxide materials, creating a material that exhibits both high lithium storage capacity and resistance to volume expansion-induced degradation
2Stability of the object's composition
If silicon oxide is used to reduce volume expansion, then structural stability is improved, but low conductivity and specific surface area result in unstable life performance
Solution Approach 1:
The patent optimizes the particle size parameter of silicon oxide to a specific range (D50: 1-20 μm, FWHM: 2-6), which simultaneously improves electrical conductivity by reducing electron transport path length and enhances specific surface area for lithium ion interaction, thereby resolving the contradiction between structural stability and life performance stability
3Stability of the object's composition
If carbon-based material is used to ensure stability and reversibility, then electrochemical stability is improved, but capacity limitation occurs
Solution Approach 1:
The patent employs silicon oxide as a composite negative electrode material that integrates the electrochemical stability and reversibility characteristics of oxide materials with the high theoretical capacity advantage of silicon-based materials, overcoming the capacity limitation of traditional carbon-based materials while maintaining stable electrochemical performance
Data Source
AI summary
A negative electrode active material for a lithium secondary battery, including silicon oxide particles, wherein the silicon oxide has a full width at half maximum peak ranging between 2 and 6 in a particle size distribution and the silicon oxide particles have an average particle size (D50) of 1 μm to 20 μm, and a negative electrode and a lithium secondary battery comprising the same. The negative electrode active material according to the disclosure has outstanding life performance and output performance.