Silicon Monoxide Negative Electrode Material for Better Cycle Life
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon-based materials face challenges in achieving cycle characteristics comparable to carbon-based batteries, with insufficient inhibition of electrolyte liquid decomposition on the negative electrode active material surface during repeated charge and discharge, leading to poor long-term cycle durability.
Innovation Solution
A negative electrode active material comprising silicon monoxide particles with a specific particle size distribution (D0.1: 1.2 μm≤D0.1≤3.0 μm, D10: 3.5 μm≤D10≤7.0 μm, D50: 6.0 μm≤D50≤15.0 μm, D99.9: 25.0 μm≤D99.9≤50.0 μm) and a BET specific surface area (1.0 m2/g≤Sm≤3.5 m2/g), which inhibits reaction with the electrolyte liquid, improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative electrode active material to increase battery capacity, then theoretical capacity increases significantly, but cycle characteristics deteriorate due to electrolyte decomposition on surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters (D10, D50, D90) and specific surface area (S BET) of silicon monoxide particles. By optimizing these physical parameters within specific ranges, the invention achieves both high battery capacity and improved cycle characteristics, resolving the contradiction between capacity increase and cycle durability.
Solution Approach 2:
The patent uses silicon monoxide (SiO) as a composite material that combines the high capacity advantage of silicon with the stability benefits of oxide materials. This composite approach allows the negative electrode active material to achieve theoretical capacity close to pure silicon while maintaining better structural stability and reduced electrolyte decomposition compared to pure silicon.
2Quantity of substance
If particle size is reduced to increase reaction area, then battery capacity increases, but electrolyte decomposition increases leading to poor cycle characteristics
Solution Approach 1:
The patent resolves this contradiction by optimizing the specific surface area (S BET) parameter within a specific range (0.5 to 3.0 m²/g) and controlling the particle size distribution parameters (D10, D50, D90). This parameter optimization ensures sufficient reaction area for high capacity while limiting excessive surface area that would cause harmful electrolyte decomposition.
Solution Approach 2:
The patent applies local quality by creating a specific particle size distribution where different particle sizes are present in controlled proportions. This distribution ensures that fine particles provide sufficient reaction area for capacity while coarser particles in the mixture reduce the overall specific surface area to minimize electrolyte decomposition, achieving local optimization of the particle population.
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 specified particle size distribution and BET specific surface area significantly enhance the cycle characteristics of the battery by reducing electrolyte decomposition, resulting in improved long-term cycle performance.
Implementation Method 1
a BET specific surface area Sm satisfies 1.0 m2/g≤Sm≤3.5 m2/g
Data Source
AI summary
A negative electrode active material including silicon monoxide particles, wherein the silicon monoxide particles satisfy that, in volumetric basis distribution measured with a laser-diffraction method particle size distribution measurement device, an accumulative 0.1%-particle-size D0.1 satisfies 1.2 μm≤D0.1≤3.0 μm, an accumulative 10%-particle-size D10 satisfies 3.5 μm≤D10≤7.0 μm, an accumulative 50%-particle-size D50 satisfies 6.0 μm≤D50≤15.0 μm, and an accumulative 99.9%-particle-size D99.9 satisfies 25.0 μm≤D99.9≤50.0 μm, and the silicon monoxide particles satisfy that a BET specific surface area Sm satisfies 1.0 m2/g≤Sm≤3.5 m2/g. The negative electrode active material can improve cycle characteristics when used as the negative electrode active material for a negative electrode of a secondary battery.