Silicon Anode Layering With Flash Annealing for Stable Capacity
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Solution Overview
Problem
Existing methods for producing silicon anodes for lithium batteries face challenges such as uncontrolled reactions during annealing, leading to loss of active material and instability, and the need for controlled proportions of silicon and silicides for optimal performance and stability.
Innovation Solution
A method involving the repeated deposition of silicon layers on a copper substrate followed by accelerated annealing, such as flash-lamp or laser annealing, to form a stratified structure with controlled copper-silicon reactions, ensuring stable adhesion and high electrical conductivity, and the use of additional layers like carbon or metals to prevent uncontrolled silicide formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a silicon layer is deposited on a copper substrate and subjected to conventional annealing, then adhesion between silicon and copper is improved, but uncontrolled reaction occurs leading to loss of active material and complete destruction of the anode
Solution Approach 1:
A copper silicide layer is formed on the copper substrate before depositing the silicon layer. This preliminary action creates a controlled reaction layer that prevents uncontrolled reaction during subsequent annealing, thereby maintaining adhesion while preserving active silicon material.
Solution Approach 2:
The copper silicide layer acts as an intermediary between the copper substrate and the silicon layer. It mediates the interaction between copper and silicon, allowing controlled adhesion while preventing the complete reaction that would destroy the anode structure.
2Quantity of substance
If silicon is used as anode material to increase storage capacity, then energy density is improved, but volume expansion during charging leads to internal stresses and pulverization
Solution Approach 1:
The anode is structured with different layers having different properties: a copper silicide layer for stability and adhesion, and a silicon layer for high capacity. This local differentiation allows the silicon to provide high storage capacity while the copper silicide layer constrains volume expansion and maintains structural stability.
Solution Approach 2:
The anode uses a composite structure combining copper silicide and silicon layers. The copper silicide provides structural stability and constraints volume expansion, while the silicon provides high storage capacity, achieving both improved energy density and maintained structural integrity.
3Strength
If the copper substrate reacts completely with silicon during annealing to form copper silicide, then adhesion is improved, but the current collector is lost
Solution Approach 1:
The copper silicide layer is formed preliminarily on the copper substrate before silicon deposition. This controlled preliminary reaction ensures sufficient adhesion while leaving the bulk copper substrate intact to serve as a stable current collector.
Solution Approach 2:
Instead of allowing complete reaction between copper and silicon, the process is controlled to achieve partial reaction only at the substrate surface, forming a thin copper silicide layer for adhesion while preserving the majority of the copper substrate as current collector.
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 approach allows for the production of stable silicon anodes with high capacitance and controlled volume expansion, preventing the complete reaction of the copper substrate and maintaining the current collector, thus ensuring stable battery operation and improved performance.
Implementation Method 1
a first silicon layer is deposited on a substrate, preferably copper
Implementation Method 2
is subsequently subjected to accelerated annealing
Implementation Method 3
accelerated annealing, such as flash-lamp or laser annealing
Implementation Method 4
accelerated annealing, such as flash-lamp or laser annealing
Implementation Method 5
ensuring stable adhesion and high electrical conductivity, and the use of additional layers like carbon or metals to prevent uncontrolled silicide formation
Data Source
AI summary
The invention relates to a method for producing a silicon anode for lithium batteries, in which a silicon layer is deposited on a substrate, preferably copper, and is then subjected to short-term tempering. The object of the present invention is to provide a method which allows control of the proportions of silicon relative to silicide and metal, in which method a compromise should be found between the maximum proportion of pure silicon which must be available as active material for the intercalation of lithium, with at the same time a sufficient number of inactive regions to achieve stability and good electrical conductivity, and with a sufficient anode layer thickness with a high silicon content for a high capacitance. According to the invention, said object is achieved in a first approach by repeating the deposition of the silicon layer and the subsequent short-term tempering at least once.