Atomic-Level Carbon-Modified SiO Anodes for Low-Expansion Cycling
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Solution Overview
Problem
Current silicon monoxide negative electrode materials for lithium-ion batteries face challenges with poor conductivity, significant volume expansion, and constant SEI film growth during cycling, limiting their energy density and rapid charging performance.
Innovation Solution
A uniformly modified silicon monoxide negative electrode material is developed by embedding carbon atoms at an atomic level within silicon monoxide, forming amorphous Si—C bonds, which enhances conductivity and reduces volume expansion, achieved through a method involving the introduction of a carbon substance-containing solution into a deposition vapor, followed by high-temperature vaporization and deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode material is used to achieve high gram capacity, then lithium storage capacity is improved, but volume expansion increases significantly
Solution Approach 1:
Carbon atoms are embedded within the silicon monoxide crystal structure at atomic level, with carbon atoms occupying interstitial sites and forming Si-C bonds. This nested structure allows the carbon to be integrated within the silicon monoxide matrix, providing structural support during lithium insertion/extraction cycles and reducing volume expansion while maintaining high lithium storage capacity.
Solution Approach 2:
The invention creates a composite material by incorporating carbon atoms into silicon monoxide to form a uniformly modified structure. This composite approach combines the high capacity benefits of silicon-based materials with the structural stability and conductivity advantages of carbon, resulting in a material that exhibits both high lithium storage capacity and reduced volume expansion.
2Volume of moving object
If carbon coating is applied to protect silicon monoxide, then volume expansion is reduced, but conductivity improvement is limited to surface only
Solution Approach 1:
The invention performs preliminary action by embedding carbon atoms within the silicon monoxide structure during the material synthesis process itself, rather than applying carbon coating afterward. This ensures that carbon is integrated into the crystal structure from the beginning, providing both volume expansion reduction and conductivity enhancement simultaneously throughout the entire material.
Solution Approach 2:
The invention merges the protective function and conductivity enhancement function into a single integrated structure. Carbon atoms serve dual purposes: they provide structural support to reduce volume expansion during cycling, and simultaneously create conductive pathways throughout the material. This combines multiple functions into one unified material structure.
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 modified material exhibits improved conductivity, reduced volume expansion, and enhanced cycle and rate performance, leading to increased energy density and better rapid charging capabilities.
Implementation Method 1
each of the carbon atoms is bonded to a silicon atom to form an amorphous Si—C bond
Implementation Method 2
the mixed vapor is cooled and deposited, so that carbon atoms are uniformly embedded in silicon monoxide at an atomic level
Implementation Method 3
A carbon substance-containing solution is introduced into a deposition vapor for preparing silicon monoxide, so that it can be rapidly vaporized at high temperature
Data Source
AI summary
A negative electrode material comprises silicon monoxide and carbon atoms, wherein the carbon atoms are uniformly distributed in silicon monoxide at an atomic level; a carbon atom is bonded to a silicon atom to form an amorphous Si—C bond, and an X-ray diffraction energy spectrum has no SiC crystallization peak; in solid-state nuclear magnetic resonance detection of the uniformly modified negative electrode material, there is a resonance peak between −10 ppm and −20 ppm; the average particle size of negative electrode material particles is 1 nm-100 μm, and the specific surface area is 0.5 m2/g-40 m2/g; the mass of the carbon atoms accounts for 0.1%-40% of the mass of silicon monoxide. The material has small volume expansion in a lithium dis-embedding process, the conductivity coefficient for lithium ions is high, and the cycle performance and rate performance of the material are improved.