Bi-Layer Composite Anode for Lithium Microbatteries
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Solution Overview
Problem
Current microbattery technologies face challenges such as leakage, dielectric breakdown, and parasitic cell degradation due to limitations in 3D fabrication, leading to commercial impracticality, especially in miniaturized forms, and lack effective integration of all-solid-state energy storage devices with high energy and power density.
Innovation Solution
A novel lithium energy storage device design featuring a bi-layer structure with a lithium metal layer and interphase on a silicon substrate, combined with a solid polymer electrolyte and specific cathode and anode compositions, which inhibits lithium ion movement and provides structural integrity, enabling efficient charge storage and protection within a 3D trench structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If 3D fabrication techniques are used to create microbattery structures, then energy density is improved, but manufacturing precision deteriorates due to fabrication failures
Solution Approach 1:
The microbattery is divided into multiple planar layers (anode, electrolyte, cathode, encapsulation) fabricated sequentially using standard CMOS-compatible thin film deposition techniques. This segmentation allows each layer to be independently optimized and controlled, avoiding the manufacturing defects associated with monolithic 3D fabrication while achieving high energy density through vertical stacking.
Solution Approach 2:
The invention transitions from conventional planar (2D) battery architecture to a vertical stacked (3D) configuration by depositing multiple functional layers in the vertical dimension. This dimensional transformation increases energy density by utilizing vertical space while maintaining manufacturing precision through sequential thin film deposition processes that are well-established in semiconductor fabrication.
2Volume of moving object
If miniaturization is pursued to reduce device size, then device footprint is reduced, but reliability deteriorates due to leakage and dielectric breakdown
Solution Approach 1:
The microbattery employs thin film encapsulation layers (e.g., silicon nitride, silicon oxide) deposited using atomic layer deposition (ALD) or chemical vapor deposition (CVD) to provide leak-free containment and dielectric protection. These conformal thin film shells effectively prevent ion leakage and electrical breakdown even in miniaturized structures by providing uniform, defect-free barriers at the micro-scale.
Solution Approach 2:
The encapsulation structure uses composite multilayer designs combining different dielectric materials (e.g., alternating layers of silicon nitride and silicon oxide) to provide both mechanical integrity and chemical barrier properties. This composite approach enhances reliability by preventing both ion leakage and dielectric breakdown through synergistic material properties.
3Ease of manufacture
If standard thin film encapsulation is used to control performance, then manufacturing ease is improved, but parasitic cell degradation increases
Solution Approach 1:
The encapsulation layer parameters (thickness, composition, deposition temperature) are optimized to balance manufacturing feasibility with performance. For example, ALD-deposited silicon nitride layers at controlled thicknesses (50-200 nm) provide adequate barrier properties against parasitic degradation while remaining compatible with standard CMOS fabrication processes. The invention also employs plasma treatment or surface modification parameters to reduce interfacial resistance and prevent degradation at electrode-electrolyte interfaces.
4Quantity of substance
If lithium metal is integrated to increase capacity, then energy density is improved, but safety deteriorates due to dendrite formation and short circuits
Solution Approach 1:
A solid electrolyte layer (e.g., sulfide-based or oxide-based solid electrolyte) is introduced as an intermediary between the lithium metal anode and the cathode. This solid electrolyte acts as a physical barrier that prevents dendrite penetration and short circuits while maintaining ionic conductivity. It mediates the interaction between lithium metal and the rest of the cell, enabling high capacity utilization without safety hazards.
Solution Approach 2:
The lithium metal is contained within an inert solid electrolyte environment that prevents direct contact with moisture or oxygen, eliminating safety hazards associated with reactive lithium metal. The solid electrolyte creates an chemically inert barrier that allows lithium metal to function at high capacity while preventing dendrite formation and external short circuits.
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 enhances the durability and performance of energy storage devices by reducing interfacial impedance, increasing energy density, and preventing mechanical breakdown, thereby extending the lifecycle and reliability of miniaturized energy storage systems.
Implementation Method 1
The electrolyte has an electrolyte top interface with the cathode and an electrolyte bottom interface with the anode
Implementation Method 2
A portion inside the full thickness of the electrolyte coverage contains a separator (dielectric) material which prevents the conduction of electrons through the electrolyte medium
Implementation Method 3
Once the bi-layer (Li-metal with the interphase) is formed and the substrate is saturated with Lithium ions, the bi-layer acts as a barrier to inhibit Lithium ions from entering or leaving the Lithium saturated substrate
Data Source
AI summary
A Lithium energy storage device comprising a cathode, electrolyte, anode, and substrate. The materials contained in the anode and electrolyte region are electrochemically altered during initial formation and exposed to current cycles to create a lower impedance composite anode. The resulting composite anode bottom is a bi-layer comprising: i. a lithium metal layer and ii. a silicon-based interphase layer. The bi-layer acts as a barrier to inhibit Lithium ions from entering or leaving a Lithium saturated substrate, once the interphase surface is formed and the substrate is saturated with Lithium ions. This prevents cell failure from large volume changes/stresses during charge/discharge cycles and enables a significant decrease in cell impedance to enable better rechargeable cell performance.