Silicon-Ti-Fe Alloy Matrix for High-Capacity Battery Anodes
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Solution Overview
Problem
Lithium secondary batteries face challenges with carbon-based negative electrode materials, such as graphite, in achieving high charge/discharge capacity due to volume expansion and contraction issues with silicon-based alternatives, which affect cycle performance and mass production feasibility.
Innovation Solution
A negative electrode active material comprising a phase A of active silicon and a phase B of a metal alloy matrix, specifically a Si-Ti-Fe ternary alloy, with a Vickers hardness of 500 Hv or more, that surrounds the active silicon to suppress expansion and contraction, ensuring high hardness, embrittlement, and excellent electric conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode material to achieve high charge/discharge capacity, then the charge/discharge capacity is improved, but volume expansion and contraction occur during charge/discharge cycles, leading to degradation of cycle properties
Solution Approach 1:
The patent employs a composite material structure consisting of silicon particles embedded in a metal matrix. The silicon phase provides high charge/discharge capacity through lithium intercalation, while the metal matrix (containing Al, Si, and transition metals) provides structural stability and suppresses volume expansion. This composite approach allows the system to achieve both high capacity and good cycle properties by combining the advantages of different materials.
2Reliability
If physical shape control of silicon thin film is used to reduce expansion and contraction, then the cycle property is improved, but the productivity of the thin film is severely lowered, making it difficult to apply to mass production
Solution Approach 1:
The patent changes the fundamental parameter of the negative electrode material from thin film morphology to particulate morphology embedded in a metal matrix. This parameter change allows the material to be produced through conventional metallurgical processes rather than complex thin film deposition techniques, significantly improving productivity while maintaining the ability to control expansion through the metal matrix structure.
3Stability of the object's composition
If graphite is used as a negative electrode active material, then the structure is stable, but it is difficult to achieve high charge/discharge capacity
Solution Approach 1:
The patent creates a composite material where silicon particles (providing high capacity) are embedded in a metal matrix (providing structural stability). This composite structure allows the system to achieve both high charge/discharge capacity from the silicon and structural stability from the metal matrix, overcoming the limitations of using either material alone.
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 solution provides a high-capacity, efficient, and long-lasting secondary battery with improved cycle properties and manufacturing efficiency by effectively managing volume changes and maintaining structural integrity during charge/discharge cycles.
Implementation Method 1
a metal alloy matrix including a silicon and a transition metal... surrounds the core of the active silicon of the phase A... expansion of the pole plate may be effectively suppressed during the charge/discharge
Implementation Method 2
when lithium ions transferred to the negative electrode are intercalated into the silicon (Si)... the lithium ions are deintercalated from the silicon (Si)
Implementation Method 3
the alloy matrix shows both of the high hardness and the embrittlement property due to its innate alloy composition... Vickers hardness of 500 Hv or more
Data Source
AI summary
The present invention relates to a negative electrode active material and a secondary battery. In the present invention, the negative electrode active material maintaining excellent cell efficiency and lifespan while showing high-capacity properties, and the secondary battery using the negative electrode may be provided.