Silicon Oxide Anode Composition With Disordered C-Si Bonds
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Solution Overview
Problem
Silicon-based negative electrode materials, particularly silicon oxide, face challenges with poor internal conductivity, which hinders rapid charging performance and leads to volume expansion issues in batteries.
Innovation Solution
A silicon-based negative electrode material with carbon atoms uniformly distributed at an atomic level within a silicon oxide matrix, forming disordered C—Si bonds, and an optional carbon coating layer, is developed using a gas-phase mixing method, enhancing internal conductivity and reducing volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode materials are used to achieve high energy density, then battery capacity is improved, but volume expansion occurs during cycling
Solution Approach 1:
The carbon coating layer acts as a flexible protective shell around the silicon oxide particles. This thin film structure accommodates volume expansion during lithium insertion/extraction cycles while maintaining structural integrity, thus preventing particle cracking and electrolyte decomposition that would otherwise occur with pure silicon oxide.
Solution Approach 2:
The composite structure of silicon oxide with embedded disordered carbon atoms and outer carbon coating creates a material that combines the high capacity of silicon oxide with the volume stability of carbon. The carbon phases buffer the volume expansion, allowing the material to maintain its structural integrity during cycling.
2Speed
If traditional surface modification methods are used, then surface conductivity is enhanced, but rapid charging performance is limited by poor internal conductivity
Solution Approach 1:
The patent changes the physical and chemical parameters of carbon within the silicon oxide matrix by embedding disordered carbon atoms at the atomic level. This parameter change transforms the internal structure from insulating to conductive, enabling rapid charge transfer throughout the bulk material and thus improving rapid charging performance.
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 solution significantly improves the rapid charging performance and cycle stability of silicon-based negative electrodes by ensuring uniform carbon distribution and bonding at a molecular level, addressing the limitations of traditional surface modifications.
Implementation Method 1
the carbon atoms are bonded to silicon atoms to form disordered C—Si bonds
Implementation Method 2
heating the first crucible to 1300-1700° C. and the second crucible to 100-1000° C. after reducing the pressure to less than 0.1 Torr
Implementation Method 3
a mixed vapor generated by heating under reduced pressure
Implementation Method 4
cooling a mixed vapor generated by heating under reduced pressure at 400-900° C. to obtain a silicon oxide material with carbon atoms uniformly distributed at an atomic level after depositing
Data Source
AI summary
A negative electrode material comprises: carbon atoms uniformly distributed in a silicon oxide matrix at an atomic level; the carbon atoms are bonded to silicon atoms to form disordered C—Si bonds, and an X-ray diffraction energy spectrum has no SiC crystallization peak. In an X-ray photoelectron spectroscopy of the negative electrode material, there is a binding peak belonging to the C—Si bond at a location of 283.5±1 eV after a C1s energy spectrum is subjected to peak splitting. The average particle size of the 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 the silicon oxide matrix. The ultra-fine silicon obtained by gaseous treatment is bonded to highly conductive carbon to form a disordered C—Si bond structure mixed at a molecular level.