Porous Silicon Composite Anodes With Low-SEI Surface Control
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Solution Overview
Problem
Lithium-ion batteries using silicon-containing materials for anodes face issues with high volume change leading to mechanical stress, irreversible capacity loss, and SEI formation, which results in reduced cycling stability and capacity fading.
Innovation Solution
Silicon-containing materials with silicon disposed in pores and on the surface of porous particles, characterized by a specific surface area of at most 50 m2/g and a mean electrical particle resistance of at least 2 kOhm, utilizing porous particles like silicon dioxide or boron nitride with controlled porosity and morphology to enhance electrical conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as active material in anodes for lithium-ion batteries, then electrochemical capacity is improved, but volume change leads to mechanical stress and capacity fading
Solution Approach 1:
The patent uses porous particles as the base material for the anode active material. The porous structure provides void space that can accommodate the volume expansion of silicon during lithium insertion, reducing mechanical stress and preventing particle breakdown. This allows silicon to maintain its electrochemical capacity over multiple charging/discharging cycles without suffering from the typical capacity fading caused by volume changes.
Solution Approach 2:
The patent creates a composite material consisting of silicon-containing compounds deposited on porous particles. This composite structure combines the high capacity of silicon with the structural stability of the porous particle matrix, achieving both high electrochemical capacity and good cycling stability.
2Quantity of substance
If silicon-containing materials are used in anodes, then capacity is improved, but SEI formation increases leading to capacity loss
Solution Approach 1:
The porous structure provides a large surface area with controlled porosity that moderates SEI formation. The porous matrix distributes the SEI formation across many small surfaces rather than large continuous surfaces, reducing the total amount of lithium consumed in SEI formation while maintaining high capacity.
3Reliability
If specific surface area is reduced to minimize SEI formation, then capacity retention is improved, but electrical conductivity may be affected
Solution Approach 1:
The patent achieves an optimal balance by controlling the porosity and surface area of the particles. The porous structure provides sufficient surface area for lithium insertion while the controlled total surface area limits excessive SEI formation. The patent specifies a surface area range that balances these competing requirements.
Solution Approach 2:
The patent optimizes specific parameters including surface area (50-500 m²/g), porosity (0.1-0.8 cm³/g), and particle size to achieve the desired balance between electrical conductivity and SEI formation control. By carefully controlling these parameters, the patent achieves both good capacity retention and adequate electrical conductivity.
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 enables high Coulomb efficiencies and stable electrochemical behavior with minimized fading and trapping, maintaining capacity over cycles, and reduces SEI formation, leading to improved lithium-ion battery performance.
Implementation Method 1
a process for producing the silicon-containing material by thermally decomposing one or more silicon precursors in the presence of one or more porous particles, thereby depositing silicon in pores and on the surface of the porous particles
Data Source
AI summary
A silicon-containing material along with processes for producing and uses for the same. Where the silicon-containing material is based on one or more porous particles and silicon and the silicon is disposed in pores and on the surface of the one or more porous particles. The silicon-containing material has a specific surface area of at most 50 m2/g, determined by nitrogen sorption and BET evaluation and the one or more porous particles have a mean electrical particle resistance of at least 2 kOhm and a reversible delithiation capacity 0 of at most 100 mAh/g.