Silicon Oxide Graphite Anode Composition for Lithium Battery
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Solution Overview
Problem
Lithium secondary batteries face challenges in increasing capacity and service life due to the use of silicon-based negative electrode materials, which experience excessive volume change and irreversible capacity loss, particularly when using non-carbon-based materials like silicon.
Innovation Solution
A negative electrode composition comprising silicon oxide (SiOx), natural graphite, and artificial graphite, with specific BET surface area and pore volume correlations, along with single-walled carbon nanotubes (SWCNTs), to enhance conductive paths and electrode adhesion, thereby improving capacity and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then energy density is improved, but volume change occurs excessively
Solution Approach 1:
The silicon oxide particles are embedded within the graphite particle structure, creating a nested configuration where silicon oxide is contained inside graphite. This nesting approach allows the high-capacity silicon oxide to be protected by the volume-stable graphite matrix, accommodating expansion while maintaining structural integrity.
Solution Approach 2:
The invention uses a composite material system combining silicon oxide (SiOx) and graphite in a specific configuration. The composite structure leverages the high capacity of silicon oxide while using graphite's dimensional stability to constrain volume changes, achieving both high capacity and structural stability.
2Quantity of substance
If non-carbon-based negative electrode materials are used to increase capacity, then energy density is improved, but irreversible capacity loss increases
Solution Approach 1:
The invention optimizes specific physical parameters of the materials used: controlling the BET specific surface area of silicon oxide (0.3-3.0 m²/g) and graphite (0.5-2.0 m²/g), and adjusting pore volume ratios. These parameter optimizations reduce unwanted side reactions and improve initial charging-discharging efficiency, thereby reducing irreversible capacity loss.
3Quantity of substance
If silicon-based active material is used to increase capacity, then service life is improved, but electrode adhesion deteriorates
Solution Approach 1:
The invention utilizes porous graphite particles with controlled pore volume (0.003-0.020 cm³/g) and specific pore size distribution (0.003-0.020 μm). The porous structure provides pathways for stress relief during volume changes and maintains electrolyte access, thereby preserving electrode adhesion and service life despite the use of high-capacity silicon oxide.
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 composition enables high-capacity batteries with improved electrode adhesion, rapid charging capabilities, and extended service life by optimizing the specific surface areas and pore volumes of the silicon-based materials, while minimizing irreversible capacity loss.
Implementation Method 1
the conductive path between the negative electrode active material particles can be improved by together using a silicon oxide represented by SiOx (0
Implementation Method 2
The lithium secondary battery generates electric energy by oxidation and reduction reactions during intercalation and deintercalation of lithium ions
Implementation Method 3
a material having a small pore volume, and a specific surface area, and a specific pore size distribution
Data Source
AI summary
The present invention relates to an anode composition, an anode for a lithium secondary battery, comprising same, a lithium secondary battery, and a method for preparing the anode composition, the anode composition comprising a silicon oxide represented by SiOx (0<x<2), graphite, and an anode conductive material, wherein the graphite comprises natural graphite and artificial graphite, and the BET specific surface area values of the silicon oxide represented by SiOx (0<x<2), the natural graphite, and the artificial graphite are amounts increasing in the order of artificial graphite < natural graphite < silicon oxide represented by SiOx (0<x<2).