Thin-Film Battery Stacking With Thin Substrates and Hermetic Sealing
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Solution Overview
Problem
Current thin film battery (TFB) structures face challenges with low energy density due to thick support substrates and sealing layers, which limit their applications and lead to mechanical stresses and component failures from thermal expansion differences.
Innovation Solution
The use of a thin, flat substrate with temporary handlers to maintain flatness and structural integrity during manufacturing, combined with a stackable battery design and hermetic sealing, reduces substrate thickness and enhances energy density while preventing warping and mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick support substrates (50-200 um) are used to provide mechanical integrity and flat base, then mechanical stability is improved, but energy density by volume and weight deteriorates due to substrate and sealing layer occupying 25-75% of total battery thickness
Solution Approach 1:
The invention divides the battery structure into multiple thin film layers (cathode, electrolyte, anode, sealing layers) stacked on a thin substrate, with each layer performing a specific function. This segmentation allows the active battery components to constitute the majority of the structure while the substrate provides minimal necessary support, thereby improving energy density while maintaining mechanical stability through the distributed layer structure.
2Quantity of substance
If thickness of support substrate is reduced to improve energy density, then energy density by volume and weight is improved, but stresses and component failures occur during processing due to differences in coefficients of thermal expansion
Solution Approach 1:
The invention changes the substrate thickness parameter from conventional 50-200 um to a thin film range of 1-10 um, which fundamentally alters the thermal mass and thermal expansion characteristics of the support structure. This parameter change reduces the magnitude of thermal expansion stresses while maintaining sufficient mechanical support through the distributed thin film layer architecture, thereby improving energy density without sacrificing component reliability.
3Quantity of substance
If reduced sealing layer thickness is used to improve energy density, then energy density is improved, but hermetic sealing and interconnections become more difficult to achieve in small battery form factors
Solution Approach 1:
The invention employs composite sealing structures comprising multiple thin film layers with different material properties optimized for specific functions: barrier layers for hermetic sealing, conductive layers for interconnections, and structural layers for mechanical support. This composite approach enables adequate hermetic sealing and electrical interconnections in reduced thickness configurations, improving energy density while maintaining manufacturability through specialized material combinations rather than relying on single thick layers.
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 results in higher energy density TFBs with improved mechanical stability and hermetic sealing, enabling efficient production of smaller form factor batteries with high yields compatible with existing fabrication techniques.
Implementation Method 1
These stresses can be caused by differences in coefficients of thermal expansion (CTE) of the substrate and battery components (e.g. the cathode, electrolyte, anode, connections, and sealing materials) combined with temperature cycling
Data Source
AI summary
Thin Film Batteries are made of battery layers. Each battery layer has a substrate with one or more battery structures on the substrate surface. The battery structures have a first electrode connection and a second electrode, a first electrode (e.g. a cathode or anode) is electrically connected to the first electrode connection and a second electrode (e.g. an anode or cathode) is electrically connected to the second electrode connection. An electrolyte is at least partial disposed between and electrically connected to the first and second electrodes. A first edge connection on one of the substrate edges is physically and electrically connected to the first electrode connection. A second edge connection on one of the substrate edges is physically and electrically connected to the second electrode connection. An electrically insulating lamination is disposed on the substrate and covers the components except for the first and second edge connections, connected to respective battery electrodes. A first stack external connection electrical connects two or more of the first edge connections and a second stack external connection electrical connects two or more of the second edge connections. A first and second battery pole are connected to the respective first and second stack external connections. The TFBs are hermetically sealed.