Gas-Phase Silicon Coating for Porous Li-Ion Battery Anodes
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Solution Overview
Problem
Conventional methods for applying silicon to lithium battery negative electrodes face challenges in precision and controllability, especially when using porous materials, due to the need for liquid media and difficulties in high-capacity battery performance and lifespan enhancement.
Innovation Solution
A gas-phase electroreduction method is employed, where a silicon-based compound is supplied to a base material with applied electric potential to form a silicon coating layer without a liquid medium, allowing precise control and application to porous materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional liquid medium electrochemical deposition is used to reduce chlorosilane molecules to silicon, then silicon coating can be formed on the base material, but precise coating control is difficult and application to porous material is impossible
Solution Approach 1:
The invention extracts and eliminates the liquid medium from the electrochemical deposition process, transitioning to a gas-phase approach. This removal of the liquid medium enables precise coating control and makes the process applicable to porous materials that cannot be treated with liquid-based methods.
Solution Approach 2:
The invention substitutes the liquid-based electrochemical deposition mechanism with a gas-phase electroreduction mechanism. By replacing the liquid medium with gas-phase chlorosilane molecules and using electrical energy directly in the gas phase, the process achieves both precision and applicability to porous substrates.
2Quantity of substance
If silicon content is increased to achieve high capacity in negative electrode, then lithium capacity increases up to ten times of carbon-based materials, but volume expansion during charging and discharging increases and lifespan decreases
Solution Approach 1:
The invention forms a thin film silicon coating layer on the surface of the negative electrode base material rather than using bulk silicon. This thin film approach allows high lithium capacity while constraining volume expansion, as the coating layer can accommodate expansion without causing the severe mechanical degradation that occurs with bulk silicon, thereby improving lifespan.
3Reliability
If conventional carbon-based negative electrode active material is used, then lifespan is improved, but theoretical capacity is limited to only 372 mAh/g and output characteristics are significantly reduced during high-speed charging
Solution Approach 1:
The invention creates a composite structure by forming a silicon coating layer on top of a carbon-based negative electrode base material. This composite approach combines the high capacity advantage of silicon with the structural stability and lifespan benefits of carbon, while the coating structure enables faster lithium ion transport for improved output characteristics during high-speed charging.
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
This method enables stable high-capacity characteristics and improved lifespan in lithium-ion batteries by forming a silicon coating layer on the negative electrode, minimizing irreversible capacity loss and accommodating volume expansion during charging and discharging.
Implementation Method 1
gas-phase reducing the silicon-based compound to form a silicon coating layer on the surface of the base material
Implementation Method 2
reducing chlorosilane molecules to silicon is to dissolve the molecules in a liquid medium, such as liquid electrolyte or molten metal salts, and to reduce molecules to silicon by electrochemical deposition
Data Source
AI summary
The present invention relates to a method for preparing silicon by using gas-phase electroreduction and, more specifically, to a method in which a silicon-based compound is gas-phase supplied, without a liquid medium, onto the surface of a base metal having a potential applied thereto, and thus silicon is reduced and applied onto the surface of the base metal.