Flexible Battery Cell Interconnects for High Current and Vibration

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Solution Overview

Problem

Conventional methods for assembling battery cell assemblies face challenges in achieving high current carrying capacity, robust construction, flexibility, cost-effective manufacturing, and reducing the number of failure points, particularly due to thermal instability and the complexity of connecting hundreds of lithium-based cells.

Innovation Solution

A battery assembly using flexible conductors made from solder tinned copper braid and bands that apply force to secure the conductors to the cells, allowing for high current transmission and flexibility, while reducing the need for welding and minimizing failure points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large interconnects are used to carry heavy current load, then current carrying capacity is improved, but the interconnects become too stiff to allow for cell movement during thermal expansion or vibration

Engineering Contradiction:

Improvecurrent carrying capacityVSAvoidflexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent uses a flexible conductor made of multiple thin, flexible conductive layers (such as foil or ribbon) that can bend and flex. This flexible conductor is wrapped around the cell group and secured with bands, providing both the necessary current carrying capacity and the flexibility to accommodate cell movement during thermal expansion or vibration without compromising electrical connection.

Inventive Principle:

Principle #30Flexible shells and thin films

2Ease of manufacture

If thin interconnects are used to weld to cells, then ease of welding is improved, but current carrying capacity is reduced

Engineering Contradiction:

Improvewelding easeVSAvoidcurrent carrying capacity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the interconnect function into multiple thin conductive layers (such as multiple foils or ribbons) that are stacked or layered together. Each thin layer can be easily welded to the cell terminals, while the combined structure of multiple layers provides sufficient current carrying capacity. The flexible conductor wraps around the cell group, distributing the electrical connection across multiple points.

Inventive Principle:

Principle #1Segmentation

3Reliability

If conventional two-part interconnects are used, then current carrying capacity is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvecurrent carrying capacityVSAvoidinterconnect structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the functions of multiple interconnect elements into a single flexible conductor that wraps around the entire cell group. This unified structure eliminates the need for separate rigid interconnects and flexible adapters, reducing the number of components and assembly steps while maintaining both current carrying capacity and flexibility. The flexible conductor serves as both the electrical connector and the flexible element simultaneously.

Inventive Principle:

Principle #5Merging (Combining)

4Strength

If multiple weld connections are made to achieve robust assembly, then strength is improved, but the number of failure points increases

Engineering Contradiction:

Improveassembly robustnessVSAvoidfailure points

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent uses bands (such as metal or plastic straps) to pre-secure the flexible conductor to the cell group before final assembly. This preliminary mechanical securing ensures that the conductor maintains proper contact and alignment, reducing the reliance on multiple weld connections. The bands provide structural support and positioning, allowing for fewer but more reliable electrical connections.

Inventive Principle:

Principle #10Preliminary action

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 provides a reliable, durable, and cost-effective method for connecting battery cells, enabling high current carrying capacity and flexibility, while reducing thermal damage and manufacturing complexity, and minimizing failure points.

Implementation Method 1

The bands apply a force to the flexible conductor as the bands attempt to return to an unstretched state, thus connecting the flexible conductor to the contact points of the battery cells

Methodology Applied

Scientific EffectElastic recovery: Elasticity

Implementation Method 2

The flexible conductor is held to the contact points of the individual batteries by a plurality of bands... The flexible conductor is structured from a material such as solder tinned copper braid that can withstand a current in the order of 300 amps

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS7807290B2Battery cell assembly

Publication Date: 2010.10.05 ZERO MOTORCYCLES INC

AI summary

A battery cell assembly includes a plurality of battery cells. Each battery cell comprises a first end that is positively charged and a second end that is negatively charged. One or more flexible conductors are adapted to electrically connect the plurality of battery cells. A plurality of bands secures the one or more flexible conductors to the plurality of battery cells. The flexible conductors are configured to withstand a current on the order of 300 amps and a minimum temperature of 170° F.