Ceramic Electrochemical Cell Sealing with Gold Metallization
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Solution Overview
Problem
Conventional sealing techniques fail to provide consistent longevity and hermeticity in miniature electrochemical cells with volumes less than 0.5 cc, due to issues with polymeric adhesive layers allowing ingress and egress of contaminants, and the challenge of accommodating dimensional changes during charging and discharging.
Innovation Solution
The use of ceramic casings with a solid electrolyte and metal feedthroughs, where the ceramic substrates are machined to create a recess for the electrode assembly and sealed using a gold or titanium interlayer, allowing for expansion and contraction without compromising hermeticity, and featuring a gap between the electrode assembly and the casing to accommodate dimensional changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymeric adhesive layers are used to seal the cell, then assembly is simplified, but hermeticity and longevity are compromised due to ingress and egress of contaminants
Solution Approach 1:
The patent uses a composite sealing structure combining a metal seal (providing hermeticity) with a polymeric adhesive layer (providing assembly ease). The metal seal ensures contaminant barrier while the adhesive simplifies the bonding process, resolving the contradiction between ease of manufacture and hermeticity.
2Volume of moving object
If cell size is reduced below 0.5 cc, then miniaturization is achieved, but conventional sealing techniques become impractical as seals occupy major portion of cell volume
Solution Approach 1:
The patent employs thin-film metallization layers deposited on ceramic substrates to create seals. These thin-film seals provide hermetic sealing in a minimal thickness, enabling miniaturization below 0.5 cc while maintaining sealing effectiveness without occupying excessive cell volume.
3Volume of moving object
If fill port size is reduced for miniaturization, then cell volume decreases, but hermetic sealing of the fill port becomes increasingly difficult
Solution Approach 1:
The patent eliminates the fill port entirely by using a solid electrolyte that does not require filling. This extraction of the fill port function resolves the contradiction by removing the sealing challenge altogether while maintaining miniaturization benefits.
4Reliability
If hermetic encapsulation is implemented for solid electrolyte cells, then longevity is improved, but dimensional flexibility to accommodate cycling-induced expansion and contraction is reduced
Solution Approach 1:
The patent uses thin-film metallization seals on ceramic substrates that provide hermetic sealing while maintaining sufficient flexibility. The thin-film structure and ceramic substrate combination allow the seal to accommodate cycling-induced dimensional changes without compromising hermeticity, thus maintaining both longevity and dimensional flexibility.
5Strength
If ceramic substrates are used for high temperature withstand during deposition, then manufacturing robustness is improved, but adaptation to dimensional changes during cycling is reduced
Solution Approach 1:
The patent creates a composite structure combining rigid ceramic substrates (providing temperature withstand during deposition) with thin-film metallization layers (providing dimensional flexibility). The ceramic substrate ensures manufacturing robustness while the thin-film seal accommodates cycling-induced dimensional changes, resolving the contradiction between strength and adaptability.
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 design ensures hermetic sealing and flexibility to accommodate dimensional changes, enhancing the longevity and reliability of miniature electrochemical cells, particularly suitable for small-sized cells that require robust sealing and minimal volume usage.
Implementation Method 1
an electrochemical cell which is sufficiently hermetic to prevent ingress of moisture and egress of electrolyte
Implementation Method 2
since secondary electrochemical cells activated with a solid electrolyte typically undergo expansion and contraction during charging and discharging
Implementation Method 3
ceramic substrates sealed together with an intermediate ring-shaped metallization
Data Source
AI summary
A miniature electrochemical cell having a total volume that is less than 0.5 cc is described. The cell casing is formed by joining two ceramic casing halves together. One or both casing halves are machined from ceramic to provide a recess that is sized and shaped to contain the electrode assembly. The opposite polarity terminals are electrically conductive feedthroughs or pathways, such as of gold, and are formed by brazing gold into tapered via holes machined into one or both ceramic casing halves. The two ceramic casing halves are separated from each other by a metal interlayer, such as of gold, bonded to a thin film metallization layer, such as of titanium, that contacts an edge periphery of each ceramic casing half. A solid electrolyte of LiPON (LixPOyNz) is used to activate the electrode assembly.