Electrode Termination Contact Interface for Ultracapacitors

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Solution Overview

Problem

Current double layer capacitor designs face challenges in minimizing electrode interface equivalent series resistance (ESR) and achieving high operating voltages, leading to variability in manufacturing and reduced energy density and power output.

Innovation Solution

The method involves forming a first electrode foil with active carbon deposits and current collecting tab portions, defining and folding zones with a separator to create a symmetric and efficient electrode termination contact interface, which reduces ESR by ensuring high-quality terminations and tight manufacturing tolerances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional laser welding techniques are used to fuse electrode foil to terminal cap, then manufacturing process is simple, but only 15%-40% of foil wraps are fused leading to high ESR and manufacturing variability

Engineering Contradiction:

Improveelectrode termination interface qualityVSAvoidconsistency of foil fusion

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces traditional laser welding (thermal/mechanical system) with a mechanical compression system using a termination contact interface that applies uniform pressure to fuse electrode foil tabs to terminal caps. This mechanical approach ensures consistent contact across all foil wraps without the variability inherent in laser welding processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent merges multiple electrode foil tabs and terminal cap contacts into a single integrated termination contact interface assembly. This consolidation ensures uniform pressure distribution and consistent electrical contact across all connections, eliminating the variability that occurs when individual welding points are made separately.

Inventive Principle:

Principle #5Merging (Combining)

2Power

If electrode interface ESR is reduced through improved termination techniques, then energy density and power output increase, but manufacturing complexity increases

Engineering Contradiction:

Improvepower output ratingVSAvoidtermination interface structure

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent uses thin, flexible conductor plates or foils as the termination contact interface that can conform to the electrode assembly geometry. This flexibility allows the simple termination structure to achieve intimate contact with multiple foil wraps simultaneously, reducing ESR without requiring complex rigid structures.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The termination contact interface is designed to automatically distribute compression force uniformly across all electrode tabs through its flexible geometry and elastic properties. This self-adjusting mechanism eliminates the need for complex control systems or multiple adjustment points, achieving low ESR through the material's inherent properties rather than external control.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7433174B2Method of making, apparatus, and article of manufacturing for an electrode termination contact interface

Publication Date: 2008.10.07 MAXWELL TECHNOLOGIES GLOBAL LLC

AI summary

An electrode termination contact interface, adapted for use in an energy storage device, is disclosed. The disclosed apparatus and article of manufacture function to lower equivalent series resistance of the electrode termination contact interface for energy storage devices, such as for example a capacitor device or a battery device. In one embodiment of the present teachings, an ultracapacitor electrode termination contact interface, adapted to increase reliability and manufacturing yield of such devices is disclosed.