Implantable Battery Tab Assembly to Prevent Electrode Fanning
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Solution Overview
Problem
Implantable medical device batteries face issues with mechanical stress and 'fanning' of electrode stacks during discharge, leading to potential electrical shorting and failure of laser welds.
Innovation Solution
The battery assembly incorporates spacers of varying thicknesses, a rivet through the tab/spacer stack to prevent mechanical 'fanning', and a shim between the interconnect spacer stack and the battery housing to limit stress on laser welds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welds are used to attach tabs in the battery assembly, then manufacturing precision and initial strength are achieved, but mechanical stress during discharge causes weld failure and electrical shorting
Solution Approach 1:
The patent applies beforehand cushioning by introducing spacers with varying thicknesses and a rivet system before the battery undergoes discharge cycles. These components pre-position the tabs and absorb mechanical stresses that would otherwise transfer to the laser welds during battery operation, preventing weld failure and maintaining electrical connectivity throughout the battery's service life.
2Volume of moving object
If the electrode stack is tightly assembled to maximize energy density, then volume efficiency is improved, but mechanical stress causes 'fanning' and potential electrical shorting
Solution Approach 1:
The patent applies segmentation by dividing the electrode stack into discrete segments separated by spacers of varying thicknesses. This segmentation allows the stack to maintain high density while accommodating differential expansion and contraction of individual electrode plates during charge-discharge cycles, preventing the 'fanning' effect and maintaining stable electrical isolation between electrodes.
3Stability of the object's composition
If spacers of varying thicknesses are used to prevent 'fanning', then electrode stack stability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by varying the thickness of spacers at different locations within the electrode stack based on local requirements. Thinner spacers are placed where minimal separation is needed, while thicker spacers are positioned where greater accommodation of dimensional changes is required. This localized differentiation prevents 'fanning' and maintains stability without uniformly increasing complexity throughout the entire assembly.
Data Source
AI summary
In some examples, a battery assembly for an implantable medical device. The battery assembly may include an electrode stack comprising a plurality of electrode plates, wherein the plurality of electrode plates comprises a first electrode plate including a first tab extending from the first electrode plate and a second electrode plate including a second tab extending from the second electrode plate; a spacer between the first tab and the second tab; and a rivet extending through the first tab, second tab, and spacer, wherein the rivet is configured to mechanically attach the first tab, second tab, and spacer to each other.