Silicon Oxide Anode Composite for Stable High-Capacity Cycling
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Solution Overview
Problem
Existing silicon-based negative electrode materials for secondary batteries suffer from rapid deterioration due to insulation, particle desorption, and increased contact resistance caused by large volume changes during charge/discharge cycles, leading to poor initial charge/discharge efficiency and cycle characteristics, hindering commercialization.
Innovation Solution
A negative electrode material comprising a matrix of silicon oxide and composite oxides with doping elements, embedded with crystalline silicon nanoparticles, exhibiting compressive strength of 100 MPa or more and specific X-ray diffraction and Raman peak ratios, ensuring mechanical and electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as negative electrode material to achieve high capacity, then energy density is improved, but volume change during charge/discharge causes particle desorption and contact resistance increase
Solution Approach 1:
Crystalline silicon nanoparticles are embedded within an amorphous silicon oxide matrix, creating a nested structure where the silicon particles are contained within the oxide framework. This nesting approach allows the high-capacity silicon to be protected by the structurally stable oxide matrix, preventing particle desorption while maintaining electrochemical activity
Solution Approach 2:
The invention uses a composite material system combining amorphous silicon oxide and crystalline silicon nanoparticles. The composite structure leverages the structural stability and volume buffer capacity of the oxide matrix while utilizing the high lithium storage capacity of crystalline silicon, achieving both high capacity and good cycle characteristics
2Reliability
If silicon oxide is used as negative electrode material to improve structural stability, then cycle characteristics are improved, but initial charge/discharge efficiency decreases due to irreversible lithium loss
Solution Approach 1:
The invention creates local quality differences by having crystalline silicon nanoparticles (high reactivity, high capacity) distributed within an amorphous silicon oxide matrix (structural stability, volume buffer). The local crystalline regions provide high initial efficiency while the surrounding amorphous oxide provides structural stability, achieving both goals simultaneously
Solution Approach 2:
The invention changes the physical state parameter of silicon from bulk crystalline to nanoparticulate form embedded in amorphous oxide. This parameter change reduces the volume of irreversible lithium silicate formation while maintaining high capacity, improving initial charge/discharge efficiency compared to bulk silicon oxide
3Quantity of substance
If particulate silicon is used to achieve high capacity, then energy density is improved, but insulation and particle desorption occur during cycling
Solution Approach 1:
The crystalline silicon nanoparticles are nested within the amorphous silicon oxide matrix, which acts as a protective framework. This nesting prevents particle desorption during cycling while maintaining the high capacity of the crystalline silicon particles
Solution Approach 2:
The amorphous silicon oxide matrix serves as an intermediary between the crystalline silicon nanoparticles and the electrolyte environment. It provides structural support and prevents direct contact that would lead to particle desorption, while still allowing lithium ion transport
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 maintains structural integrity and electrochemical performance, preventing physical damage during manufacturing and ensuring high capacity retention and efficiency, making it suitable for practical commercialization.
Implementation Method 1
a negative electrode material for a secondary battery having improved capacity, initial efficiency, and cycle characteristics
Implementation Method 2
a secondary battery capable of charging and discharging
Implementation Method 3
it has been found that when silicon is dispersed in a silicon-based oxide-based matrix in a nanoparticle form and has residual compressive stress, the mechanical and electrochemical properties of the negative electrode material are significantly improved
Implementation Method 4
when silicon is dispersed in a silicon-based oxide-based matrix in a nanoparticle form and has residual compressive stress, the mechanical and electrochemical properties of the negative electrode material are significantly improved
Implementation Method 5
a compressive strength (St) of the particles is 100 MPa or more
Data Source
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Figure 5
AI summary
Provided is a negative electrode material for a secondary battery, which is in a particle form including: a matrix including a silicon oxide, a composite oxide of silicon and one or more doping elements selected from the group consisting of alkali metals, alkaline earth metals, and post transition metals, or a mixture thereof; and silicon nanoparticles dispersed and embedded in the matrix, wherein a compressive strength (St) of the particles is 100 MPa or more, and a ratio (A1/A2) between an area of a first peak (A1) and an area of a second peak (A2) satisfies 0.8 to 6, a diffraction angle 2θ being positioned in a range of 10° to 27.4° in the first peak and being positioned in a range of 28±0.5° in the second peak, in an X-ray diffraction pattern using a CuKα ray.