Porous SiOx Anode Materials Mitigating Volume Expansion
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Solution Overview
Problem
Lithium ion batteries face challenges in increasing energy density due to volume expansion issues with silicon-based anode materials, which limit their industrial application potential.
Innovation Solution
A porous material with the formula SiaMbOx, featuring a microporous and/or mesoporous structure and doping with elements like Al, Si, P, Mg, Ti, and Zr, is developed, which provides space for expansion and improves lithium ion diffusion, leading to enhanced reversible capacity and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode materials are used to increase energy density, then theoretical capacity is improved (4200 mAh/g), but volume expansion problem worsens (300% or above during cycling)
Solution Approach 1:
The patent employs porous silicon-oxygen materials with controlled pore structures to accommodate volume expansion during lithium insertion/extraction cycles. The porous architecture provides internal void space that absorbs expansion stress, preventing material fracture while maintaining electrical conductivity and lithium ion transport pathways.
Solution Approach 2:
The patent creates composite silicon-oxygen materials combining silicon particles with oxygen-containing phases (such as SiOx where 0.5 < x ≤ 2). This composite structure leverages the high capacity of silicon while the oxygen-containing phase acts as a buffer to mitigate volume expansion, achieving a synergistic effect that balances capacity and stability.
2Volume of moving object
If silicon-oxygen materials are used to mitigate volume expansion, then expansion ratio is reduced (to 118%), but reversible capacity needs further improvement
Solution Approach 1:
The patent applies local quality optimization by creating non-uniform pore distributions and varying SiOx compositions within different regions of the material. High-silicon regions provide maximum capacity while oxygen-rich regions and pore structures provide expansion buffering, with each local zone optimized for its specific function.
Solution Approach 2:
The patent systematically varies critical parameters including SiOx composition (x value), pore size distribution, particle morphology, and doping elements to optimize the balance between reversible capacity and volume expansion. By adjusting these parameters, the material achieves enhanced lithium ion diffusion pathways while maintaining structural integrity.
3Reliability
If graphite materials are used as anode, then safety and stability are improved, but energy density is limited (close to theoretical capacity of 372 mAh/g)
Solution Approach 1:
The patent utilizes porous silicon-oxygen anode materials that combine the safety advantages of oxide structures with the high capacity potential of silicon. The porous architecture ensures structural stability during cycling while providing sufficient lithium insertion sites to achieve energy density significantly higher than conventional graphite anodes.
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 SiaMbOx material achieves higher first coulombic efficiency, better rate performance, and reduced battery expansion ratio, optimizing the electrochemical performance of lithium ion batteries.
Implementation Method 1
the microporous and/or mesoporous structure can provide space for expansion of the material during the cycle
Implementation Method 2
can inhibit the reaction of the organic macromolecules in the electrolyte with Si inside the material
Implementation Method 3
nanocrystallization of the microporous material is beneficial to the diffusion of Li ions and significantly improves the rate performance
Implementation Method 4
doping can improve the structural stability of the material
Data Source
AI summary
The present application relates to a porous material and preparation methods thereof, and anodes and devices including the same. The porous material provided by the present application includes a material of the formula SiaMbOx, wherein the ratio of x to a is about 0.6 to about 1.5, and the ratio of a to b is about 8 to about 10,000, wherein M includes at least one selected from the group consisting of Al, Si, P, Mg, Ti and Zr. The anode and an electrochemical device including the porous material exhibit higher rate performance, higher first coulombic efficiency, higher cycle stability and lower cycle expansion ratio.