Lithium Microbattery Encapsulation with Alumina Buffer Layer
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Solution Overview
Problem
Lithium microbatteries face challenges in encapsulation due to sensitivity to air and moisture, requiring a protective barrier that also accommodates volume variations during charge and discharge cycles, while maintaining high barrier levels and chemical compatibility.
Innovation Solution
A lithium microbattery with a protective cover fixed directly to the stack of active layers using a polymerizable glue, where a buffer structure comprising an alumina layer is interposed between the active layers and the glue, ensuring effective protection and adhesion, and the alumina layer is deposited using Atomic Layer Deposition to block lithium diffusion and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective cover is fixed directly to the active layers using a large bead of glue, then the barrier level and mechanical strength are improved, but the useful surface area of the microbattery is reduced
Solution Approach 1:
The patent applies a thin film buffer structure (alumina layer) between the active layers and the glue, replacing the need for a large bead of glue. This thin film provides the necessary barrier function while occupying minimal space, thus preserving the useful surface area of the microbattery.
Solution Approach 2:
The patent uses a composite encapsulation system consisting of multiple layers: the protective cover, the buffer structure (alumina layer), and the glue layer. This composite structure combines the advantages of each material to achieve high barrier performance without requiring a large glue bead, thereby maintaining the useful surface area.
2Productivity
If the encapsulation system is made thinner to reduce dimensions, then the productivity and compactness are improved, but the mechanical strength to accommodate volume variations is reduced
Solution Approach 1:
The patent employs a composite encapsulation system with multiple functional layers: a thin protective cover for compactness, a buffer structure (alumina layer) for chemical compatibility and barrier function, and a glue layer for mechanical bonding. This composite structure achieves both compactness and mechanical strength by distributing functions across different thin layers.
Solution Approach 2:
The patent uses thin film structures throughout the encapsulation system, including the protective cover and buffer layer, which provide adequate mechanical strength and flexibility to accommodate volume variations during charge-discharge cycles while maintaining a compact overall thickness.
3Adaptability or versatility
If a buffer structure is added between the active layers and the glue, then the chemical compatibility and adhesion are improved, but the device complexity increases
Solution Approach 1:
The patent implements the buffer structure as a thin alumina film deposited directly on the active layers. This thin film approach provides the necessary chemical compatibility and adhesion properties without adding significant structural complexity or thickness to the encapsulation system.
Solution Approach 2:
The patent changes the chemical parameters of the encapsulation system by introducing an alumina buffer layer with specific chemical properties that ensure compatibility with both the lithium-containing active layers and the polymerizable glue, thereby improving adhesion and chemical stability without substantially increasing device complexity.
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 achieves a high barrier level against oxidizing species, maintains mechanical integrity through volume variations, and ensures chemical compatibility, resulting in a compact and efficient encapsulation system with improved adhesion and cross-linking rates, meeting the requirements for reduced dimension microbatteries.
Implementation Method 1
The buffer structure is arranged between the stack of active layers and the layer of glue... the alumina layer is deposited using Atomic Layer Deposition to block lithium diffusion
Implementation Method 2
cross-linking of the polymerizable material to glue the cover onto the stack of active layers
Implementation Method 3
the alumina layer is deposited using Atomic Layer Deposition to block lithium diffusion and enhance mechanical strength
Data Source
AI summary
A lithium microbattery comprises a stack of active layers containing lithium and a protective cover covering the stack of active layers. The protective cover is fixed to the stack of active layers by means of a layer of glue.A buffer structure comprising at least one alumina layer is arranged between the stack of active layers and the layer of glue, the buffer structure being in contact with said stack of active layers.