Modified Silicon Particles for High-Capacity Battery Electrodes
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Summary
Problems
Lithium-ion batteries with silicon anodes face rapid capacity loss due to mechanical failure caused by the expansion and contraction of silicon particles during charge and discharge, leading to poor cycle life and irreversible lithium incorporation in the solid electrolyte interface.
Innovation solutions
The development of silicon particles with modified surfaces, including aluminum oxide and aluminum silicide regions extending 20 nm deep, and surface coatings of silicon carbide, which form a stable solid electrolyte interface and act as an expansion buffer, reducing mechanical failure and improving capacity retention.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If silicon particles are used in battery electrodes to increase capacity, then energy density is improved, but mechanical failure occurs due to expansion and contraction during charge and discharge
Why choose this principle:
The silicon particle is segmented into a core-shell structure where the silicon core is separated from the external environment by an aluminum oxide/aluminum silicide shell. This segmentation allows the silicon core to expand and contract during lithiation/delithiation while the shell maintains structural integrity and prevents particle disintegration, thereby maintaining cycle life while preserving high energy density.
Principle concept:
If silicon particles are used in battery electrodes to increase capacity, then energy density is improved, but mechanical failure occurs due to expansion and contraction during charge and discharge
Why choose this principle:
The aluminum oxide and aluminum silicide shell is formed on the silicon particle surface before the particle undergoes lithiation. This preliminary formation of a stable shell structure prevents direct contact between silicon and electrolyte, pre-establishes a stable solid electrolyte interface, and prevents mechanical failure before it can occur during subsequent charging and discharging cycles.
Application Domain
Data Source
AI summary:
The development of silicon particles with modified surfaces, including aluminum oxide and aluminum silicide regions extending 20 nm deep, and surface coatings of silicon carbide, which form a stable solid electrolyte interface and act as an expansion buffer, reducing mechanical failure and improving capacity retention.
Abstract
Silicon particles for use in an electrode in an electrochemical cell are provided. The silicon particles may have outer regions extending about 20 nm deep from the surfaces, the outer regions comprising an amount of aluminum such that a bulk measurement of the aluminum comprises at least about 0.01% by weight of the silicon particles. The bulk measurement of the aluminum may provide the amount of aluminum present at least in the outer regions.