Branched Silicon Anode Nanostructures for Battery Stress
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Solution Overview
Problem
Lithium-ion batteries face degradation due to the expansion of silicon anodes during charging, leading to poor energy storage and battery performance, as the rigid silicon films stress and detach during lithium insertion.
Innovation Solution
The development of branched, flexible nanostructures with a resistive semiconducting core and a lower-resistance current collecting shell, coated with an electroactive or electrically conductive material, which allows for increased surface area and flexibility to accommodate lithium insertion without breaking, thereby enhancing anode density and battery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to increase lithium storage capacity, then energy density is improved, but structural stability deteriorates due to expansion stress during charging
Solution Approach 1:
The patent segments the anode into a hierarchical structure comprising a substrate, multiple trunk structures extending from the substrate, and multiple branch structures extending from each trunk. This segmentation allows the anode to accommodate lithium insertion expansion through the distributed branched architecture, preventing the structural failure that occurs in monolithic silicon anodes while maintaining high lithium storage capacity.
2Area of stationary object
If thin film silicon is used to reduce anode area, then area footprint is reduced, but mechanical strength deteriorates causing film detachment during charging
Solution Approach 1:
The patent employs thin film structures in the form of branched nanowires rather than continuous thin films. The branched architecture provides flexibility to accommodate the 400% expansion of silicon during lithium insertion while maintaining structural integrity. The thin film nature is preserved in the branch structures, keeping the area footprint small, while the branched configuration prevents the mechanical failure and detachment seen in conventional thin film silicon anodes.
3Quantity of substance
If branched nanostructures are used to increase surface area, then lithium storage capacity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements a nested hierarchical structure where branch structures are extended from trunk structures, which themselves extend from the substrate. This nesting approach systematically organizes the complex branched architecture into manageable levels of complexity. The self-similar branching pattern at multiple scales allows for controlled manufacturing while achieving high surface area and lithium storage capacity, making the complex structure more tractable for fabrication.
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 use of branched nanostructures results in smaller, longer-lasting, and more efficient lithium-ion batteries with improved charging capacity and reduced area requirements, as they mitigate stress and prevent degradation of the anode during lithium insertion.
Implementation Method 1
converting the catalyst to a liquid phase so that 'droplets' or 'beads' are formed; exposing the liquid catalyst to a precursor gas so that at least some of the gas reacts with at least some of the liquid catalyst to form the nanostructures
Implementation Method 2
exposing the liquid catalyst to a precursor gas so that at least some of the gas reacts with at least some of the liquid catalyst to form the nanostructures
Data Source
AI summary
The invention relates to electrochemical electrodes containing branched nanostructures having increased surface area and flexibility. These branched nanostructures allow for higher anode density, resulting in the creation of smaller, longer-lasting, more efficient batteries which require less area for the same charging capacity. Also disclosed are methods for creating said branched nanostructures and electrodes.