Carbon-Coated Silicon Oxide Anode for Stable Battery Slurry
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Solution Overview
Problem
Current silicon oxide anode active materials for lithium secondary batteries have low energy density and manufacturing stability issues due to magnesium exposure on the surface, leading to pH increase and thickener shrinkage, which affects electrode uniformity and electrochemical properties.
Innovation Solution
A silicon oxide anode active material with a carbon coating layer and magnesium doping, where the magnesium hydroxide content is controlled to less than 0.05% by weight, ensuring a peak area ratio of 60% or less in the Mg1s spectrum, and a carbon content of 3-12% by weight, to prevent gas generation and maintain stable slurry viscosity during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnesium is doped on the surface of silicon oxide to improve energy density, then energy density is improved, but pH increases and thickener shrinks during slurry preparation
Solution Approach 1:
A carbon coating layer is introduced as an intermediary between the magnesium-doped silicon oxide and the slurry environment. This carbon layer prevents direct interaction between magnesium and the slurry components, eliminating pH increase and thickener shrinkage while preserving the energy density benefits of magnesium doping.
Solution Approach 2:
The harmful effect of exposed magnesium (pH increase and thickener degradation) is converted into a benefit by controlling the magnesium hydroxide content to be 60% or less in the XPS Mg1s spectrum. This controlled presence of magnesium hydroxide, combined with carbon coating, prevents slurry instability while maintaining high energy density.
2Quantity of substance
If magnesium is exposed on the surface of anode active material, then energy density increases, but electrode manufacturing stability deteriorates
Solution Approach 1:
The carbon coating layer serves as a protective intermediary that prevents magnesium from being exposed on the surface. This eliminates the harmful interactions that cause electrode non-uniformity during manufacturing, while the underlying magnesium-doped silicon oxide structure maintains high energy density.
Solution Approach 2:
The surface composition parameters are changed by controlling the magnesium hydroxide content to be 60% or less in the XPS Mg1s spectrum and maintaining carbon content at 3-12% by weight. These parameter changes ensure stable electrode manufacturing while preserving energy density.
3Manufacturing precision
If carbon coating layer is applied on silicon oxide surface, then manufacturing stability is improved, but energy density may be reduced
Solution Approach 1:
The carbon content in the coating layer is optimized to be 3-12% by weight based on the total weight of silicon oxide. This parameter range provides sufficient protection for manufacturing stability while minimizing the impact on energy density.
Solution Approach 2:
The carbon coating is applied as a thin surface layer with localized quality, providing protection where needed (at the surface) while leaving the bulk magnesium-doped silicon oxide structure intact to maintain high energy density.
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
This approach enhances the energy density and electrochemical properties of lithium secondary batteries by ensuring stable electrode manufacturing and uniformity, preventing pH-induced thickener shrinkage and gas formation, thereby improving discharge capacity and lifespan.
Implementation Method 1
a silicon oxide which includes a carbon coating layer formed on a surface thereof and is doped with magnesium
Implementation Method 2
a ratio of peak area at 1303 eV to a sum of a peak area at 1304.5 eV and a peak area at 1303 eV, which appear in a Mg1s spectrum when measuring by X-ray photoelectron spectroscopy (XPS)
Data Source
AI summary
According to embodiments of the present invention, there is provided an anode active material for a lithium secondary battery including a silicon oxide which includes a carbon coating layer on a surface thereof and is doped with magnesium. A ratio of peak area at 1303 eV to a sum of a peak area at 1304.5 eV and a peak area at 1303 eV, which appear in a Mg1s spectrum when measuring by X-ray photoelectron spectroscopy (XPS), is 60% or less.