Amorphous Alloy Anode for Lithium Ion Battery Volume Stability
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Solution Overview
Problem
Alloy-type anodes in lithium ion batteries experience poor cycle life and coulombic efficiency due to large volume changes during lithiation and delithiation, leading to internal stress and deterioration of electrical contact, which diminishes capacity over time.
Innovation Solution
The use of an amorphous alloy composition in the anode, comprising tin, silicon or aluminum, yttrium or lanthanide elements, and optional transition metals, which remains amorphous even after repetitive cycles, minimizing volume changes and maintaining electrical contact integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-type anode material is used to incorporate lithium through alloying mechanism, then the amount of lithium incorporated per unit mass increases, but large volume change occurs during lithiation and delithiation
Solution Approach 1:
The patent changes the physical state parameter of the alloy material from crystalline to amorphous. This parameter change eliminates the two-phase region formation during lithiation/delithiation, thereby reducing volume change while maintaining high lithium incorporation capacity. The amorphous structure allows for more uniform lithium distribution and prevents the sharp volume expansions contractions characteristic of crystalline alloys.
Solution Approach 2:
The patent creates a composite anode material by combining amorphous alloy particles with conductive carbon matrix and binder. This composite structure addresses the volume change issue by providing a flexible, conductive network that can accommodate the reduced volume fluctuations of the amorphous alloy while maintaining electrical contact throughout the electrode structure.
2Quantity of substance
If alloy-type anode material is used to achieve higher lithium incorporation, then capacity increases, but internal stress develops due to two-phase region formation
Solution Approach 1:
The patent changes the structural parameter of the alloy from crystalline to amorphous, which fundamentally alters the lithiation/delithiation mechanism. Instead of forming distinct two-phase regions with sharp interfaces that generate internal stress, the amorphous structure enables a more gradual, homogeneous phase transition, significantly reducing internal stress accumulation during cycling.
Solution Approach 2:
The patent converts the typically harmful two-phase region formation into a beneficial homogeneous transformation. By using amorphous material, the phase change that would normally create stress-concentrating interfaces is transformed into a uniform structural evolution, turning a source of mechanical failure into a stable, reversible process that maintains structural integrity.
3Quantity of substance
If alloy-type anode material undergoes large volume change, then lithium capacity increases, but electrical contact between alloy, conductive diluent, and binder deteriorates
Solution Approach 1:
The patent changes the volume stability parameter by using amorphous alloy material, which undergoes significantly reduced volume change during cycling. This parameter change ensures that the physical spacing and contact between alloy particles, conductive diluent, and binder remain stable, maintaining continuous electrical pathways throughout the electrode structure over many charge-discharge cycles.
Solution Approach 2:
The patent employs a composite electrode structure where amorphous alloy particles are embedded in a continuous matrix of conductive diluent and binder. This composite architecture provides multiple beneficial effects: the amorphous alloy maintains stable volume, the conductive diluent ensures electrical connectivity, and the binder holds the structure together. The synergistic combination addresses the electrical contact deterioration problem by providing redundant conductive pathways and mechanical stability.
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 amorphous alloy composition achieves high initial capacity retention and specific capacities up to 2000 mAh/g, with the alloy remaining amorphous after multiple cycles, reducing the risk of anode disintegration and maintaining battery performance.
Implementation Method 1
A second class of anode material is known that incorporates lithium through an alloying mechanism during charging
Implementation Method 2
The amorphous materials do not form a two-phase region during lithiation or delithiation that can lead to the disintegration of particles
Data Source
AI summary
Alloy compositions are described for use in anodes of lithium ion batteries. The alloy compositions contain (a) tin, (b) a second element that includes silicon, aluminum, or a combination thereof, (c) a third element that includes yttrium, a lanthanide element, an actinide element, or a combination thereof and an optional alkaline earth element, and (d) an optional transition metal. The alloy compositions are amorphous and remain amorphous even after multiple cycles of lithiation and delithiation.