Amorphous-Nanocrystalline Silicon Alloy Anode for Lithium Ion Batteries
Solution Overview
Problem
Lithium ion batteries with alloy-type anodes face issues of poor cycle life and coulombic efficiency due to large volume changes during lithium incorporation, leading to internal stress and deterioration of electrical contact, which diminishes capacity over time.
Innovation Solution
The use of an alloy composition in lithium ion batteries that combines an amorphous phase with a nanocrystalline phase, specifically containing silicon, aluminum, a transition metal, tin, indium, and a sixth element like yttrium or lanthanide, which minimizes the formation of crystalline phases and maintains electrical contact integrity during lithiation and delithiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-type anodes are used to incorporate lithium, then specific capacity is improved, but cycle life deteriorates due to large volume change and internal stress
Solution Approach 1:
The patent changes the physical state parameter of the alloy from fully crystalline to a mixture of amorphous and nanocrystalline phases. This parameter change reduces the volume expansion during lithiation from 300-400% to approximately 20%, thereby maintaining structural integrity over multiple cycles while preserving high specific capacity
Solution Approach 2:
The patent creates a composite material system combining amorphous phase and nanocrystalline phase in specific proportions (30-70 wt% amorphous, 70-30 wt% nanocrystalline). This composite structure synergistically combines the high capacity of alloy materials with the structural stability needed for long cycle life
2Quantity of substance
If alloy-type anodes are used to incorporate lithium, then specific capacity is improved, but electrical contact deteriorates due to volume change
Solution Approach 1:
The patent changes the morphological parameter of the alloy from large crystalline structures to nanocrystalline and amorphous phases. This parameter change prevents the deterioration of electrical contact between alloy particles, conductive diluent, and binder by maintaining a compact structure that preserves electrical pathways during lithiation and delithiation
3Reliability
If intercalation-type anodes are used, then cycle life is improved, but specific capacity deteriorates due to low lithium incorporation
Solution Approach 1:
The patent creates a composite material system combining amorphous phase and nanocrystalline phase in specific proportions (30-70 wt% amorphous, 70-30 wt% nanocrystalline). This composite structure synergistically combines the high capacity of alloy materials with the structural stability needed for long cycle life
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 composition enhances the specific capacity and cycle life of lithium ion batteries by reducing internal stress and maintaining electrical contact, allowing for faster recharging and improved retention of capacity over repetitive cycles.
Implementation Method 1
A second class of anode material is known that incorporates lithium through an alloying mechanism during charging
Implementation Method 2
The alloy composition is a mixture of an amorphous phase that includes silicon and a nanocrystalline phase that includes tin, indium, and the sixth element
Data Source
AI summary
Alloy compositions, lithium ion batteries, and methods of making lithium ion batteries are described. The lithium ion batteries have anodes that contain an alloy composition that includes a) silicon, b) aluminum, c) transition metal, d) tin, e) indium, and f) a sixth element that contains yttrium, a lanthanide element, an actinide element, or a combination thereof. The alloy composition is a mixture of an amorphous phase that includes silicon and a crystalline phase that includes an intermetallic compound of 1) tin, 2) indium, and 3) the sixth element.