Silicon Nanocrystal Composite Negative Electrode Material
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Solution Overview
Problem
Conventional silicon-based negative electrode materials for secondary batteries suffer from rapid deterioration due to insulation, particle detachment, and high contact resistance caused by volume changes during charge/discharge cycling, leading to poor initial charge/discharge efficiency and cycle characteristics, hindering commercialization.
Innovation Solution
A negative electrode material comprising a matrix of composite oxide, including alkali metals, alkaline earth metals, and post-transition metals, with silicon nanocrystals dispersed, exhibiting specific X-ray diffraction patterns and intensity ratios, effectively suppressing irreversible reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as negative electrode materials to achieve high energy density, then battery capacity is improved, but initial charge/discharge efficiency deteriorates due to irreversible reactions
Solution Approach 1:
The patent changes the chemical composition parameters of the matrix material by incorporating specific ratios of Li2SiO3, Mg2SiO4, and other phases, transforming the material properties to reduce irreversible lithium consumption while maintaining high capacity
Solution Approach 2:
The patent creates a composite matrix containing multiple oxide phases (Li2SiO3, Mg2SiO4, etc.) combined with silicon nanocrystals, where each component contributes different functions: the oxide matrix suppresses irreversible reactions while silicon provides high capacity
2Quantity of substance
If silicon-based materials are used to achieve high energy density, then battery capacity is improved, but cycle characteristics deteriorate due to volume changes causing insulation and particle detachment
Solution Approach 1:
The oxide matrix acts as a flexible protective shell surrounding the silicon nanocrystals, accommodating volume changes during cycling while maintaining structural integrity and preventing particle detachment
Solution Approach 2:
The composite structure combines brittle silicon nanocrystals with a more tolerant oxide matrix, creating a material that leverages the high capacity of silicon while the matrix provides mechanical stability during cycling
3Ease of manufacture
If conventional silicon oxide is used as negative electrode material, then manufacturing is simplified, but initial charge/discharge efficiency deteriorates due to lithium loss from irreversible products
Solution Approach 1:
The patent modifies the oxide composition from conventional silicon oxide to a multi-phase system containing Li2SiO3, Mg2SiO4, and other phases with specific ratios, changing the chemical parameters to eliminate harmful irreversible reactions while maintaining manufacturability
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 material significantly improves initial charge/discharge efficiency and capacity retention rates, achieving efficiencies above 85% and capacity retention rates of 99% or more, outperforming conventional materials.
Implementation Method 1
silicon nanocrystals dispersed and incorporated in the matrix
Implementation Method 2
charge/discharge cycling
Implementation Method 3
effectively suppressing irreversible reactions
Implementation Method 4
In an X-ray diffraction pattern using CuKα rays, a first peak in which a diffraction angle 2θ is located in a range of 20.3° to 21.3°
Data Source
Figure 1
AI summary
The present invention relates to a negative electrode material for a secondary battery, having excellent initial charge/discharge efficiency, and, specifically, the negative electrode material for a secondary battery comprises: a matrix containing a silicon oxide, a composite oxide of silicon and at least one doping element selected from the group consisting of an alkali metal, an alkaline earth metal and a post-transition metal, or a mixture thereof; and silicon nanocrystals dispersed and incorporated in the matrix, and comprises, in an X-ray diffraction pattern using CuKα rays, a first peak of diffraction angle 2θ in the range of 20.3°-21.3°, a second peak in the range of 26°-27°, a third peak in the range of 28°-29°, and a fourth peak in the range of 30.5°-31.5°, and the ratio (I2/I4) of the maximum intensity (I2) of the second peak to the maximum intensity (I4) of the fourth peak satisfies 1-20.