Silicon Anode Slurry Passivation via Metal Coating
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Solution Overview
Problem
Silicon-based anode materials for lithium ion batteries are reactive and require careful handling in non-oxidizing environments, limiting their use in water-based slurries and affecting battery performance.
Innovation Solution
Coating silicon particles with silver and/or tin nanoparticles to form a passivation layer, allowing the use of silicon-based anodes in water-based slurries and enhancing conductivity and cycling lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used as anode active material, then battery capacity is increased, but reactivity with water-based solvents worsens
Solution Approach 1:
A passivation layer comprising metalloid oxide nanoparticles (such as SiO2, GeO2, SnO2) and/or metalloid salt nanoparticles (such as SiO, GeO, SnO, Sb2O3, Sb2O5) is introduced as an intermediary between the silicon particles and water-based solvents. This passivation layer acts as a protective barrier that prevents direct contact and harmful reactions between silicon and water, while still allowing the silicon to function as an effective anode active material with high capacity.
2Object-affected harmful factors
If silicon particles are coated with passivation layer, then reactivity is reduced, but manufacturing complexity increases
Solution Approach 1:
The coating process is merged with the slurry preparation process. The passivation layer materials (metalloid oxide/salt nanoparticles) are incorporated into the water-based slurry along with other anode components (conductive additives, binders) during a single mixing operation. This eliminates the need for separate coating steps and simplifies the manufacturing process while still providing effective passivation.
3Object-affected harmful factors
If conventional coating methods are used, then passivation is achieved, but processing in oxidizing environments remains difficult
Solution Approach 1:
The passivation layer is formed preliminarily during the slurry preparation stage, before the anode is subjected to any oxidizing environments during battery assembly and operation. By pre-establishing the protective barrier in the water-based slurry, the silicon particles are already protected when they encounter oxidizing conditions, enabling straightforward processing without requiring specialized non-oxidizing environments.
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 passivation layer prevents silicon reactivity with water-based solvents, enabling the use of silicon-based anodes in water-based slurries, improving conductivity and extending the cycling lifetime of lithium ion batteries while maintaining high energy and power density.
Implementation Method 1
forming a passivation coating on the silicon particles... the passivation layer prevents silicon reactivity with water-based solvents
Implementation Method 2
coating silicon particles with silver and/or tin nanoparticles... enhancing conductivity
Data Source
AI summary
Methods of preparing Si-based anode slurries and anode made thereof are provided. Methods comprise coating silicon particles within a size range of 300-700 nm by silver and/or tin particles within a size range of 20-500 nm, mixing the coated silicon particles with conductive additives and binders in a solvent to form anode slurry, and preparing an anode from the anode slurry. Alternatively or complementarily, silicon particles may be milled in an organic solvent, and, in the same organic solvent, coating agent(s), conductive additive(s) and binder(s) may be added to the milled silicon particles—to form the Si-based anode slurry. Alternatively or complementarily, milled silicon particles may be mixed, in a first organic solvent, with coating agent(s), conductive additive(s) and binder(s)—to form the Si-based anode slurry. Disclosed methods simplify the anode production process and provide equivalent or superior anodes.