Amorphous Silicon Alloy Electrode Composition for Lithium-Ion Batteries
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Solution Overview
Problem
Increasing silicon content in melt-spun alloys for lithium-ion battery electrodes makes it difficult to maintain an amorphous microstructure, leading to electrochemically inactive materials when high amounts of transition metal elements are used.
Innovation Solution
The development of an electrode composition with a formula Si x M y Al z, where x ≥ 60, y ≤ 0, and M represents iron and optionally titanium or zirconium, prepared by a chill block melt spinning process, combined with a binder and conductive diluent, to create an amorphous alloy that minimizes metal content while maintaining electrochemical activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon content is increased to achieve high capacity, then battery capacity is improved, but maintaining amorphous microstructure becomes difficult
Solution Approach 1:
The invention changes the compositional parameters by strictly limiting transition metal content to ≤5 atomic percent while maintaining high silicon content (x≥60). This parameter change allows the alloy to maintain amorphous microstructure at high silicon concentrations, resolving the contradiction between achieving high capacity and maintaining the required microstructure.
Solution Approach 2:
The invention creates a composite amorphous alloy system combining silicon, aluminum, and limited transition metals (Fe, Ti, Zr) that work synergistically. This composite approach enables the material to achieve both high silicon content for capacity and maintained amorphous structure through the beneficial interactions between components.
2Stability of the object's composition
If transition metal elements are increased to maintain amorphous microstructure, then microstructure stability is improved, but electrochemical activity decreases
Solution Approach 1:
The invention optimizes the parameter range of transition metal content, setting it to ≤5 atomic percent (and preferably ≤3 atomic percent). This precise parameter control maintains sufficient microstructure stability while preventing excessive transition metal content from causing electrochemical inactivity, thus resolving the contradiction between stability and activity.
Solution Approach 2:
The invention applies local quality by selectively using specific transition metal elements (Fe, Ti, Zr) in controlled amounts rather than using any transition metal indiscriminately. This selective approach ensures that the transition metals present provide both microstructure stabilization and electrochemical activity, rather than merely suppressing the amorphous structure.
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 electrode composition achieves high capacities and good cycle life while minimizing metal content, ensuring electrochemically active materials for lithium-ion batteries.
Implementation Method 1
These alloys have an amorphous microstructure
Implementation Method 2
Melt-spun alloys containing silicon, aluminum, and various transition metal elements have been proposed for use as electrodes
Data Source
Figure 1~2
Figure 3~4
AI summary
An electrode composition for a lithium ion battery that includes an amorphous alloy having the formula SixMyAl2 where x, y, and z represent atomic percent values and (a) x + y + z = 100, (b) x = 55, (c) y < 22, (d) z > 0, and (e) M is one or more metals selected from the group consisting of manganese, molybdenum, niobium, tungsten, tantalum, iron, copper, titanium, vanadium, chromium, nickel, cobalt, zirconium, yttrium, and combinations thereof.