Al2O3-Protected 3D Silicon Anodes for Controlled Lithium Plating
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Solution Overview
Problem
Current lithium-based microbatteries face challenges in achieving high energy and power density, especially in miniaturized devices, due to limitations in charge transfer across the silicon interface and the lack of predictable and controllable methods for lithium metal distribution.
Innovation Solution
The use of Al2O3 composite 3D patterned and porous silicon electrodes, along with in-situ electrochemical formation products, enables the creation of anode layered lithium-based energy storage devices with improved charge transfer and lithium metal distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal electrodes are used to achieve high theoretical specific capacity, then energy capacity is improved, but charge transfer control and lithium distribution predictability worsen
Solution Approach 1:
A thin aluminum oxide (Al2O3) layer is introduced as an intermediary between the silicon substrate and lithium metal. This layer mediates the charge transfer process and controls lithium nucleation, transforming the unpredictable direct lithium-silicon interface into a controlled three-layer system that enables predictable lithium distribution while maintaining high capacity
Solution Approach 2:
The invention changes the physical and chemical parameters of the interface by introducing Al2O3 with specific thickness (nanometer scale) and composition. This parameter change transforms the charge transfer characteristics and lithium nucleation behavior, enabling controlled lithium metal distribution while preserving high energy capacity
2Volume of moving object
If device volume is decreased for miniaturization, then device size is improved, but energy and power density per unit volume worsen
Solution Approach 1:
The aluminum oxide layer is applied locally at the critical silicon-lithium interface region, providing targeted control of charge transfer and lithium nucleation exactly where needed. This localized intervention enables high energy density in miniaturized devices without requiring bulk material changes
Solution Approach 2:
The invention creates a composite structure combining silicon substrate, aluminum oxide intermediate layer, and lithium metal. This composite material system achieves superior energy density by combining the high capacity of lithium with the controlled interface properties of Al2O3, enabling miniaturization without sacrificing volumetric energy density
3Manufacturing precision
If aluminum oxide layer is added to control charge transfer, then lithium distribution control is improved, but device complexity worsens
Solution Approach 1:
The aluminum oxide layer is applied as a thin, inexpensive coating that can be deposited using standard semiconductor manufacturing techniques. Despite its nanometer-scale thickness, it provides disproportionate control over lithium distribution, effectively managing complexity through a simple, scalable solution
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
This approach enhances the volumetric energy and power densities of lithium energy storage devices, while also improving their design predictability and versatility, and is compatible with CMOS manufacturing processes for mass production.
Implementation Method 1
Aluminum Oxide (Al2O3), organic/inorganic hybrids, are some of the leading additives used for increasing electrode and cell performance. Al2O3 on silicon has popular 'self-healing' benefits, yet the mechanism remains unknown for this benefit.
Implementation Method 2
Aluminum is known as a material which enables enhanced stabilization of Lithium-containing electrodes. Accordingly, the use of metals and metal oxides as Li-plating nucleation sites has been investigated in the prior art.
Implementation Method 3
the use of metals and metal oxides as Li-plating nucleation sites has been investigated in the prior art
Implementation Method 4
focus is placed on the charge transfer across the silicon interface. Interfacial additives and in-situ chemistries are significant contributors in controlling this charge transfer throughout the bulk substrate and interfacial regions
Data Source
AI summary
One or more trenches in a silicon substrate have an electrically active surface at a trench base and metal layer disposed on the electrically active surface. Precursor materials are disposed and/or formed on the metal layer in the trench. An anode is patterned either exclusively in the 3D trench or in the 3D trench, sidewalls and field of the substrate, where the anode patterning transforms and/or moves the precursor materials in the trench into some novel compositions of matter and other final operational structures for the device, e.g. layers of metallic Lithium for energy storage and different concentrations of Lithium-silicon species in the substrate. A multi-faceted mechanism is disclosed for Al2O3 silicon interfacial additives. When the anode is patterned both in and outside the 3D wells, Al2O3 provides an for electron-conductive Li-metal interface that enables homogenous plating on both the insulated substrate field as well as active silicon trench base where Al2O3 acts as a barrier to Li—Si diffusion. When the anode is patterned only in the 3D trench, Al2O3 additive creates a robust, flexible, Li-permeable interface upon charge cycling, which preserves the 3D textured structure of the porous silicon anode. Additionally, the Al2O3 additive is mobilized deeper into the bulk silicon in parallel with Li+ and a conductive plasticizer upon progressive cycling—where the lithiated Al2O3 particles nucleate at defect sites and prevent mechanical degradation of the silicon anode through a combined bridge and spacer mechanism. By selecting different defined anode patterns to deposit on the 3D substrate, final operational characteristics, properties, structures, and charge storage performance for the device can be predictably designed and manufactured.