Doped Silicon Oxide Anode Composition for Volume-Change Stability
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Solution Overview
Problem
Silicon-based negative electrode materials for secondary batteries suffer from rapid deterioration due to insulation, particle detachment, and increased contact resistance caused by volume changes, leading to poor initial charge/discharge efficiency and cycle characteristics.
Innovation Solution
A negative electrode material comprising a matrix with silicon oxide and a composite oxide of silicon doped with alkali or alkaline earth metals, combined with silicon nanoparticles, exhibits specific X-ray diffraction and Raman peak ratios, ensuring a capacity retention rate of 95% or more and compressive stress uniformity, enhancing mechanical and electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as negative electrode material to increase capacity, then energy density is improved, but cycle characteristics deteriorate due to volume change causing insulation and particle detachment
Solution Approach 1:
The silicon is divided into nanoparticles (1-50 nm diameter) and dispersed within the porous oxide matrix. This segmentation prevents large-scale volume changes that cause particle detachment, while maintaining high capacity through the high surface-area-to-volume ratio of nanoparticles.
Solution Approach 2:
The oxide matrix provides a localized environment with different mechanical and electrical properties than bulk silicon. The porous structure and doping create local regions that accommodate volume expansion and maintain conductivity, allowing the silicon nanoparticles to function at their full capacity potential without suffering from bulk silicon's deterioration problems.
Solution Approach 3:
The invention creates a composite material system combining silicon nanoparticles with a doped oxide matrix (such as TiO2, Nb2O5, or Ta2O5). This composite structure synergistically combines the high capacity of silicon with the structural stability and conductivity of the oxide matrix, resolving the contradiction between capacity and cycle life.
2Reliability
If silicon oxide is used as negative electrode material to improve cycle stability, then initial charge/discharge efficiency is improved, but lithium is lost due to irreversible products
Solution Approach 1:
The oxide matrix is doped with metals (such as Ti, Nb, Ta) to change its electrical and structural parameters. This doping reduces the oxide's tendency to form irreversible lithium products while maintaining structural stability, thereby improving initial charge/discharge efficiency without sacrificing cycle stability.
Solution Approach 2:
The doped oxide matrix acts as an intermediary between the silicon nanoparticles and the electrolyte. It mediates the lithium insertion/extraction process, preventing direct harmful reactions between silicon and electrolyte that would cause irreversible capacity loss, while still allowing efficient lithium 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 achieves high discharge capacity and stable cycle characteristics, enabling practical commercialization by maintaining capacity retention and preventing structural damage during charge-discharge cycles.
Implementation Method 1
as charge/discharge cycling is repeated, battery characteristics rapidly deteriorate due to insulation, particle detachment, and increase in contact resistance due to a large change in volume of silicon
Implementation Method 2
a large change in volume of silicon
Implementation Method 3
a matrix containing silicon oxide, a composite oxide of silicon with at least one doping element selected from the group consisting of alkali metals, alkaline earth metals and post-transition metals, or a mixture thereof
Implementation Method 4
in an X-ray diffraction pattern using CuKα rays, the ratio (A1/A2) of a first peak area (A1) in which the diffraction angle 2θ is located in the range of 10° to 27.4° and a second peak area (A2) in which the diffraction angle 2θ is located in the range of 28±0.5° satisfies 0.8 to 6
Implementation Method 5
a full width at half maximum (FWHM) of a Raman peak of nanoparticulate silicon contained in the negative electrode material may be larger than a full width at half maximum (FWHM) of a Raman peak of bulk single crystal silicon
Data Source
AI summary
Provided is a negative electrode material for a secondary battery. The negative electrode material for a secondary battery comprises: a matrix containing silicon oxide, a composite oxide of silicon with at least one doping element selected from the group consisting of alkali metals, alkaline earth metals and post-transition metals, or a mixture thereof.